Clinical Outcomes and Predictive Factors for Failure With Isolated MPFL Reconstruction for Recurrent Patellar Instability: A Series of 211 Reconstructions With a Minimum Follow-up of 3 Years

Derotational distal femur osteotomy with medial patellofemoral ligament reconstruction can get good outcomes in the treatment of recurrent patellar dislocation with excessive TT-TG and increased femoral anteversion

Background

Surgery is the main treatment for recurrent patellar dislocation (PD). However, due to the complexity of anatomical factors, there is still a lack of consensus on the choice of combined surgical methods. This study aimed to compare the clinical and radiological outcomes of medial patellofemoral ligament reconstruction combined with derotational distal femur osteotomies (MPFLR + DDFO) and combined with tibial tubercle osteotomies (MPFLR + TTO) for recurrent PD with increased femoral anteversion angles (FAA) and excessive tibial tubercle-trochlear groove (TT-TG) distance.

Methods

In this retrospective analysis, MPFLR + DDFO and MPFLR + TTO patients from 2015 to 2020 were included. Group A (MPFLR + DDFO, n = 42) and B (MPFLR + TTO, n = 46) were formed. Clinical outcomes included physical examinations, functional outcomes (Kujala, Lysholm, International Knee Documentation Committee (IKDC), visual analog scale (VAS) and intermittent and persistent osteoarthritis pain scale (ICOAP), Tegner scores), and complications. The Caton-Deschamps index (CD-I), patellar title angle, patellar congruence angle, patella-trochlear groove distance, TT-TG distance, and FAA were used to assess radiological outcomes.

Results

All clinical outcomes improved significantly in both groups, but Group A had significantly better postoperative scores than Group B (Kujala: 89.8 ± 6.4 vs. 82.9 ± 7.4, P < 0.01; Lysholm: 90.9 ± 5.1 vs. 81.3 ± 6.3, P = 0.02; IKDC: 87.3 ± 9.0 vs. 82.7 ± 8.0, P < 0.01; Tegner: 6.0 (5.0, 9.0) vs. 5.0 (4.0, 8.0), P = 0.01). However, there was no significant difference in the VAS and ICOAP scores between the two groups. No dislocation recurrences occurred. Radiological outcomes improved significantly in both groups, but Group A had better outcomes. After surgery, the patellar height of 88.5% (23/26) patients in Group A and 82.8% (24/29) patients in Group B was restored to normal (the Caton-Deschamps index <1.2).

Conclusions

Both MPFLR + TTO and MPFLR + DDFO obtained satisfactory clinical and radiological outcomes in the treatment of recurrent PD with increased FAA and excessive TT-TG. However, the outcomes of MPFLR + DDFO were better and should be considered a priority. MPFLR + TTO may be not necessary for such patients.

Reconstruction of the medial patellofemoral ligament through a double bundle of a single patellar tract and quadriceps tendons combined with medial displacement of lateral hemi-tibial tuberosity for treating low-grade recurrent patella dislocation

PURPOSE

The present study aimed to assess the clinical efficacy and imaging results of reconstruction of the medial patellofemoral ligament through a double bundle of single patellar tract and quadriceps tendons combined with medial displacement of lateral hemi-tibial tuberosity for treating low-grade recurrent patella dislocation.

METHODS

Twenty-three patients with recurrent patellar dislocation, including ten males and 13 females, with 23 knee joints were enrolled according to the relevant criteria. Reconstruction of the medial patellofemoral ligament was performed through a double bundle of a single patellar tract and quadriceps tendons combined with medial displacement of lateral hemi-tibial tuberosity. Knee function was evaluated using visual analog scale (VAS) score, International Knee Documentation Committee (IKDC) score, Lysholm score, Tegner score, and Kujala score at pre- and postoperative stages. Patellar stability was assessed by CT scans measuring tibial tuberosity-trochlear groove (TT-TG) distance, lateral patella displacement (LPD), congruence angle (CA), and patellar tilt angle (PTA).

RESULTS

All 23 patients were effectively followed up for 13-28 months (mean: 21.91 ± 4.14 months). At the last follow-up, the postoperative VAS score, IKDC score, Lysholm score, Tegner score, and Kujala score of 23 patients were 1.13 ± 0.82, 87.35 ± 3.17, 90.22 ± 1.28, 4.35 ± 0.65, and 89.26 ± 1.96, respectively, as compared to the preoperative values of 5.91 ± 1.13, 30.96 ± 5.09, 30.30 ± 2.98, 1.26 ± 0.62, and 27.87 ± 3.46, respectively, and these differences were statistically significant (P < 0.001). At the last follow-up, the postoperative TT-TG, LPD, CA, and PTA values of the 23 patients were 8.80 ± 1.85 mm, 6.01 ± 1.77 mm, 11.32 ± 6.18°, and 9.35 ± 2.88°, respectively, compared to the preoperative values of 18.77 ± 1.74 mm, 14.90 ± 4.07 mm, 37.82 ± 5.71°, and 23.58 ± 3.24°, respectively, and the differences were statistically significant (P < 0.001). No relevant complications were observed in the 23 patients.

CONCLUSIONS

Reconstruction of the medial patellofemoral ligament through a double bundle of a single patellar tract and quadriceps tendons combined with medial displacement of lateral hemi-tibial tuberosity for treating low-grade recurrent patella dislocation showed satisfactory medium-term efficacy, and further investigations are required to confirm the long-term efficacy of this approach.

Medial Patellofemoral Complex Reconstruction (Combined Reconstruction of Medial Patellofemoral Ligament and Medial Quadriceps Tendon-Femoral Ligament) With Semitendinosus Autograft Resulted in Similar Clinical and Radiographic Outcomes to Medial Patellofemoral Ligament Reconstruction in Treating Recurrent Patellar Dislocation

PURPOSE

To compare clinical and radiographic outcomes of medial patellofemoral ligament reconstruction (MPFL-R) and medial patellofemoral complex reconstruction (MPFC-R) for recurrent patellar dislocation. Outcome measures were compared based on the Insall-Salvati index.

METHODS

Patients who were diagnosed with recurrent patellar dislocation and underwent either MPFL-R or MPFC-R (combined reconstruction of MPFL and medial quadriceps tendon-femoral ligament) were retrospectively analyzed. Group allocation was based on surgical procedure and patient characteristics were collected. Clinical assessments included patient-reported outcome measures (PROMs) and return-to-sports rates. Minimal clinically important difference analysis was performed. A subgroup analysis of PROMs was carried out between patients with an Insall-Salvati index ≤1.2 versus >1.2. The patellar tilt angle, lateral patellar displacement, and bisect offset ratio were measured pre- and postsurgery. Functional failures and complications were assessed.

RESULTS

Overall, 70 patients (72 knees) in the MPFL-R group and 58 patients (61 knees) in the MPFC-R group were included. Patient characteristics were comparable between the groups. At a minimum follow-up of 24 (mean, 50.6 ± 22.1) months, all PROMs were substantially improved (P < .001), without significant intergroup differences. The percentages of patients reaching the minimal clinically important difference were similar after MPFL-R and MPFC-R: 98.6% versus 93.4% (International Knee Documentation Committee), 97.2% versus 98.4% (Lysholm), 98.6% versus 100% (Kujala), and 77.8% versus 72.1% (Tegner). The subgroup analysis based on patellar height and the return-to-sport rates also suggested comparable results. Radiographic evaluation demonstrated significantly smaller lateral patellar displacements (P = .004) and bisect offset ratios (P < .001) but similar patellar tilt angles after MPFC-R. Four (5.6%) patients receiving MPFL-R and 2 (3.3%) patients receiving MPFC-R reported recurrence of functional instability, without statistically significant difference.

CONCLUSIONS

MPFC-R resulted in similar overall clinical and radiographic outcomes to MPFL-R in treating recurrent patellar dislocation. MPFC-R might not provide additional benefits for patients with an Insall-Salvati index >1.2.

LEVEL OF EVIDENCE

Level IV, therapeutic, retrospective cohort study.

Mid-term outcomes of temporary medial distal femoral hemiepiphysiodesis with and without medial patellofemoral ligament repair for recurrent patellar instability in skeletally immature patients with genu valgum

Genu valgum contributes to patellar instability, though outcomes following temporary hemiepiphysiodesis via eight plating are less understood. The purpose of this study was to evaluate the outcomes and need for additional procedures following temporary hemiepiphysiodesis for the treatment of pediatric genu valgum and patellar instability, as well as evaluating the utility of a concurrent medial patellofemoral ligament (MPFL) repair. Patients who underwent medial distal femoral epiphysiodesis for the treatment of genu valgum and recurrent patellar instability were identified. Inclusion criteria were minimum 1-year follow-up and lack of concurrent ligamentous reconstruction. Patients were contacted to complete a questionnaire which included the International Knee Documentation Committee (IKDC) form and questions pertaining to knee function and patient satisfaction. Thirty-one patients aged 12.0 ± 1.9 years underwent 47 guided growth procedures and were included in final analysis. Seventeen knees (36%) required subsequent surgery for patellar instability. All patients requiring subsequent surgery were female, compared with 70% of patients not requiring subsequent surgery ( P  = 0.017). The MPFL repair group underwent fewer subsequent procedures to address instability, though this difference was NS (17 vs. 46%, P  = 0.318). Mean IKDC score at 5.3 years follow-up among 18 survey respondents was 78.6. Medial distal femoral hemiepiphysiodesis may partially address recurrent patellar instability in skeletally immature patients with genu valgum. Concurrent MPFL repair may minimize the need for subsequent procedures to address recurrent instability. While correcting alignment may be helpful, patients should be aware of the potential need for further patellar instability surgery. Level of evidence: IV, case series.

Postoperative Bracing after Medial Patellofemoral Ligament Reconstruction

It is unclear if bracing is necessary after isolated medial patellofemoral ligament reconstruction (MPFLr) for recurrent patellar instability. We hypothesize that patients who did not use a brace will have similar outcomes to those who were braced postoperatively. A retrospective review of patients who underwent isolated MPFLr from January 2015 to September 2020 at a single institution was performed. Those with less than 6 weeks of follow-up were excluded. The braced group was provided a hinged-knee brace postoperatively until the return of quadriceps function, which was determined by the treating physical therapist (brace, "B"; no brace, "NB"). Time to straight leg raise (SLR) without lag, recurrent instability, and total re-operations were determined. Univariate analysis and logistic regression were used to evaluate outcomes (statistical significance, p < 0.05). Overall, 229 isolated MPFLr were included (B: 165 knees, 146 patients; NB: 64 knees, 58 patients). Baseline demographics were similar (all p > 0.05). Median time to SLR without lag was shorter in the NB group (41 days [interquartile range [IQR]: 20-47] vs. 44 days [IQR: 35.5-88.3], p = 0.01), while return to sport times were equivalent (B: 155 days [IQR: 127.3-193.8] vs. NB: 145 days [IQR: 124-162], p = 0.31). Recurrent instability rates were not significantly different (B: 12 knees [7.27%] vs. NB: 1 knee [1.56%], p = 0.09), but the re-operation rate was higher in the brace group (20 knees [12.1%] vs. 0 [0%], p = 0.001). Regression analysis identified brace use (odds ratio [OR]: 19.63, 95% confidence interval [CI]: 1.43-269.40, p = 0.026) and female patients (OR: 2.79, 95% CI: 1.01-7.34, p = 0.049) to be associated with needing reoperation. Recurrent instability rates and return to sport times were similar between patients who did or did not use a hinged knee brace after isolated MPFLr. Re-operation rates were higher in the braced group. Retrospective Comparative Study, Level III.

Patellar tilt, congruence angle, and tibial tubercle-trochlear groove distance are correlated with positive J-sign in adolescents

PURPOSE

The J-sign is a clinical evaluation tool that assesses for patellar maltracking and is considered positive if lateral translation of the patella in extension, in the pattern of an inverted J is observed. This study aims to determine the association of clinical J-sign with imaging features noted on dynamic kinematic computed tomography (DKCT).

METHODS

A retrospective review was conducted by reviewing the clinical records of all patients aged 18 years or younger who had a CT patellar tracking scan done between 1 January 2005 to 31 December 2016 in a single institution. Patients who had the presence or absence of a 'J-sign' evaluated clinically were included. Radiographic parameters evaluated using the axial cuts include the patellar tilt angle, congruence angle, Dejour's classification, femoral sulcus angle, trochlear groove depth, and Wiberg's classification. Patients were then divided into two groups based on the presence or absence of J-sign on clinical examination. The radiographic measurements were then analyzed for association with the presence or absence of J-sign on clinical examination.

RESULTS

Patients with a positive J-sign had an increased patellar tilt of 23.3° ± 14.2° and an increased congruence angle of 47.1° ± 28.5° when measured in extension as compared to a patellar tilt of 18.3° ± 10.8° and a congruence angle of 32.1° ± 20.8° in patients with a negative J-sign (p = 0.024 and 0.004, respectively). Comparisons of the change in congruence angles with the knee in full extension and at 20° flexion also yielded significantly higher change of 28.0° ± 20.4° in patients with a positive J-sign as compared to 11.9° ± 17.5° in patients with a negative J-sign. Patients with a positive J-sign also had an increased TT-TG distance of 17.6 ± 5.6 mm as compared to a TT-TG distance of 14.7 ± 6.9 mm in patients with a negative J-sign (p = 0.01).

CONCLUSION

Patients with a positive J-sign had an increased patellar tilt and an increased congruence angle when measured in extension. Increased TT-TG distance was also significantly associated with positive J-sign. Patients with a positive J-sign also had a greater change in their congruence angle when measured with the knee in full extension and at 20° of flexion.

Medial Patellofemoral Ligament Reconstruction Using Pedicled Quadriceps Tendon Autograft Yields Similar Clinical and Patient-Reported Outcomes but Less Donor-Site Morbidity Compared With Gracilis Tendon Autograft

PURPOSE

To compare clinical and patient-reported outcome measures (PROMs) in patients with recurrent patellar dislocation after medial patellofemoral ligament (MPFL) reconstruction using either a gracilis tendon (GT) or quadriceps tendon autograft (QT).

METHODS

All MPFL reconstruction performed between 2017 and 2019 were reviewed retrospectively. Only patients with isolated MPFL reconstruction, without any major patellofemoral risk factors and a minimum follow-up of 24 months, were included in the study. Patients were matched with respect to sex, age, and body mass index. All patients were evaluated clinically and using PROMs.

RESULTS

A total of 64 patients with an average follow up of 28.7 ± 7.5 months were included in this study. The mean Kujala score (GT: 84.8 ± 12.9, QT: 88.9 ± 10.1), Lysholm score (GT: 89.4 ± 10.2, QT: 88.4 ± 5.0), and visual analog scale score for pain (GT: 1.9 ± 1.8, QT: 1.1 ± 1.3) did not significantly differ between both groups. Tegner activity level was significantly greater (P = .027) in the QT group (5.5 ± 1.9) compared with the GT group (4.6 ± 1.8), but within the minimal clinically important differences. Occasional patellar instability events, but no recurrent dislocation, were reported in 12.5% in the GT group and 6.3% in the QT group (P = .39). Of all patients, 90.6% in the QT and 68.8% in the HT group exceeded the PASS for the Kujala score (P = .06). Significantly more patients (59.4%) treated with GT reported donor-site morbidity in the form of sensitivity deficit at the lower leg compared with those treated with QT (3.1%, P = .001).

CONCLUSIONS

GT and QT MPFL reconstruction have comparable PROMs and patellar redislocation rates 2 years' postoperatively. Significantly more patients treated with GT reported lower-leg sensitivity deficit compared with those treated with QT.

LEVEL OF EVIDENCE

Level III, retrospective case-control study.

Influence of medial patellofemoral ligament reconstruction on patellar tracking and patellofemoral contact pressures in patella alta

Knee squatting was simulated to characterize the influence of medial patellofemoral ligament (MPFL) reconstruction on patellar tracking and contact pressures for knees with mild patella alta (Caton-Deschamps index = 1.3-1.4). Eight computational models represented knees in the pre-operative condition and following MPFL reconstruction. MPFL reconstruction significantly reduced patellar lateral tracking at low flexion angles based on bisect offset index, significantly decreased the maximum lateral pressure in mid-flexion, and significantly increased the maximum medial pressure in mid-flexion. MPFL reconstruction improves patellar stability for knees with mild patella alta and can reduce the pressure applied to lateral cartilage on the patella.

The 100 Top-Cited Articles on Medial Patellofemoral Ligament: A Bibliometric Analysis and Review

Background

The medial patellofemoral ligament (MPFL) has been investigated widely in the past 30 years, resulting in many research achievements in this field.

Purpose

To perform a comprehensive bibliometric analysis to evaluate the 100 top-cited articles on the MPFL.

Study Design

Cross-sectional study.

Methods

We searched the Scopus database in December 2022 using the terms "medial patellofemoral ligament" OR "MPFL." The search was confined to English-language articles, including technical notes, systematic reviews on clinical outcomes and/or complications, clinical studies, studies regarding complications, and basic science articles (either cadaveric or biomechanical); we excluded letters, case reports, personal opinions, guidelines, editorials, and narrative or other types of reviews. Analysis of the 100 top-cited articles was performed according to total number of citations, average citations per year (ACY), study type, country of origin, journal of publication, affiliated institution, and most published authors.

Results

The total number of citations was 16,358 (range of citations per article, 72-692). The majority of articles were published as clinical studies (54%), with cadaveric studies being the second most common (21%). Most studies originated in the United States (32%), with Japan (15%) and Germany (13%) following. The American Journal of Sports Medicine published the majority of the 100 top-cited articles (37/100; 6304 citations) as well as the 10 top-cited articles according to ACY (7/10; mean, 285.14 citations). The most prolific authors were Nomura (8 articles); Burks (6 articles); and Inoue, Sillanpää, and Dreyhaupt (5 articles each).

Conclusion

By analyzing the characteristics of the 100 top-cited articles, this study demonstrated that the MPFL is a growing and popular area of research, with the focus varying through timeline trends. Questions regarding MPFL anatomy, isometry, and biomechanics might have been answered adequately, but research regarding optimal fixation technique under various circumstances is still ongoing.

The Value of Minimal Clinically Important Difference, Substantial Clinical Benefit, and Patient-Acceptable Symptomatic State for Commonly Used Patient-Reported Outcomes in Recurrent Patellar Instability Patients After Medial Patellofemoral Ligament Reconstruction and Tibial Tubercle Transfer

PURPOSE

To identify the minimal clinically important difference (MCID), substantial clinical benefit (SCB) and patient-acceptable symptomatic state (PASS) for commonly used patient-reported outcomes (PROs) in recurrent patellar instability patients after medial patellofemoral ligament reconstruction (MPFLR) and tibial tubercle transfer (TTT), and to determine the impact of potential prognostic factors on the likelihood of achieving these values.

METHODS

From April 2015 to February 2021, patients who underwent MPFLR and TTT were retrospectively reviewed. PROs included Kujala, Knee Injury and Osteoarthritis Outcome (KOOS), Lysholm, International Knee Documentation Committee (IKDC), and Tegner score. Relevant anchor questions were provided. A distribution- or anchor-based method was adopted to determine the MCID, SCB, and PASS. Minimal detectable change (MDC) was included to confirm the validity. Univariate regression analyses were conducted to determine the potential prognostic factors.

RESULTS

One hundred forty-two patients were included. The MCID were 9.1 (Kujala), 11.1 (Lysholm), 0.9 (Tegner), 9.9 (IKDC), 9.0 (KOOS-Pain), 10.8 (KOOS-Symptoms), 10.0 (KOOS-Activities of Daily Living [ADL]), 17.8 (KOOS-Sports and Recreation [Sports/Rec]), and 12.7 (KOOS-Quality of Life [QoL]). The SCB were 14.5 (Kujala), 12.5 (Lysholm), 1.5 (Tegner), 14.5 (IKDC), 13.9 (KOOS-Pain), 14.3 (KOOS-Symptoms), 18.4 (KOOS-ADL), 47.5 (KOOS-Sports/Rec), and 15.0 (KOOS-QoL). The PASSs were 85.5 (Kujala), 75.5 (Lysholm), 3.5 (Tegner), 73.2 (IKDC), 87.5 (KOOS-Pain), 73.2 (KOOS-Symptoms), 92.0 (KOOS-ADL), 77.5 (KOOS-Sports/Rec), and 53.1 (KOOS-QoL). All SCBs were valid except KOOS-QoL. All MCIDs were valid at the 95% confidence interval (CI) except KOOS scores, the majority of which were valid at the 90% CI. A younger age was an independent prognostic factor of reaching PASS for Lysholm, IKDC, Tegner, and KOOS-ADL score. A higher baseline score was a negative prognostic factor for achieving MCID or SCB but had a slightly positive influence on the achievement of PASS.

CONCLUSIONS

This study established the MCID, SCB, and PASS for commonly used PROs and confirmed their validity in recurrent patellar instability patients after MPFLR and TTT. Younger age and lower baseline scores were prognostic factors of achieving MCID and SCB, whereas patients with higher baseline scores were more likely to report satisfaction.

LEVEL OF EVIDENCE

Level III, retrospective comparative prognostic trial.

Comparison of Failure Rates at Long-term Follow-up Between MPFL Repair and Reconstruction for Recurrent Lateral Patellar Instability

Background

The medial patellofemoral ligament (MPFL) is the primary soft tissue restraint to lateral patellar translation and is often disrupted by lateral patellar dislocation. Surgical management for recurrent patellar instability focuses on restoring the MPFL function with repair or reconstruction techniques. Recent studies have favored reconstruction over repair; however, long-term comparative studies are limited.

Purpose

To compare long-term clinical outcomes, complications, and recurrence rates of isolated MPFL reconstruction and MPFL repair for recurrent lateral patellar instability.

Study Design

Cohort study; Level of evidence, 3.

Methods

A total of 55 patients (n = 58 knees) with recurrent lateral patellar instability were treated between 2005 and 2012 with either MPFL repair or MPFL reconstruction. The exclusion criteria were previous or concomitant tibial tubercle osteotomy or trochleoplasty and follow-up of <8 years. Pre- and postoperative descriptive, surgical, imaging, and clinical data were recorded for each patient.

Results

MPFL repair was performed on 26 patients (n = 29 knees; 14 women, 15 men), with a mean age of 18.4 years. MPFL reconstruction was performed on 29 patients (n = 29 knees; 18 women, 11 men), with a mean age of 18.2 years. At a mean follow-up of 12 years (range, 8.3-18.9 years), the reconstruction group had a significantly lower rate of recurrent dislocation compared with the repair group (14% vs 41%; P = .019). There were no differences in the number of preoperative dislocations or tibial tubercle-trochlear groove distance. The reconstruction group had significantly more time from initial injury to surgery compared with the repair group (median, 1460 days vs 627 days; P = .007). There were no differences in postoperative Tegner, Lysholm, or Kujala scores at the final follow-up. In addition, no statistically significant differences were detected in return to sport (RTS) rates (repair [81%] vs reconstruction [75%]; P = .610) or reoperation rates for recurrent instability (repair [21%] vs reconstruction [7%]; P = .13).

Conclusion

MPFL repair resulted in a nearly 3-fold higher rate of recurrent patellar dislocation (41% vs 14%) at the long-term follow-up compared with MPFL reconstruction. Given this disparate rate, the authors recommend MPFL reconstruction over repair because of the lower failure rate and similar, if not superior, clinical outcomes and RTS.

Derotational distal femoral osteotomy improves subjective function and patellar tracking after medial patellofemoral ligament reconstruction in recurrent patellar dislocation patients with increased femoral anteversion: A systematic review and meta-analysis

PURPOSE

The purpose of this study is to systematically review and quantitatively analyse the clinical outcomes of combined derotational distal femoral osteotomy (D-DFO) and medial patellofemoral ligament reconstruction (MPFL-R) in the treatment of recurrent patellar dislocation (RPD) with increased femoral anteversion angle (FAA).

METHODS

This study was performed in line with PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) and AMSTAR (Assessing the Methodological Quality Of Systematic Reviews) Guidelines. PubMed, Embase, Web of Science and Cochrane Library databases were searched to identify studies reporting clinical outcomes of combined D-DFO and MPFL-R in RPD patients with increased FAA. Data on patient-reported outcome measures, radiological parameters, patellar tracking as revealed by J-sign and complications were extracted based on the inclusion criteria. The Methodological Index for Non-Randomized Study score was used for quality assessment. Review Manager and R statistical software were used to perform the statistical analysis.

RESULTS

Eleven studies with a total of 569 knees in 553 patients were included. Patients were predominantly female (79%). The weighted mean of FAA decreased from 33.6° to 13.0° (weighted mean difference = 20.59; p < 0.00001) after the combined procedure. Significant improvements (p < 0.00001) were identified in the Lysholm score (weighted mean: 55.5 vs. 80.4), International Knee Documentation Committee (IKDC) score (weighted mean: 52.8 vs. 78.6) and Kujala score (weighted mean: 54.5 vs. 80.6). The incidence of residual J-sign ranged from 14.3% to 38.3% with an overall pooled rate of 28.2% (95% confidence interval = 22.8%-33.6%). The overall redislocation rate was 1.1%. No patients experienced surgical site infection or bone nonunion. Two studies compared the clinical outcomes of MPFL-R with and without D-DFO. Compared with isolated MPFL-R, the combined procedure yielded a better Lysholm score (weighted mean: 84.9 vs. 79.3, p < 0.0001), IKDC score (weighted mean: 84.1 vs. 79.9, p = 0.001), Kujala score (weighted mean: 84.3 vs. 79.4, p < 0.0001) and a lower residual J-sign rate (26/97 [26.8%] vs. 44/105 [41.9%], p = 0.02), respectively.

CONCLUSION

The combination of D-DFO and MPFL-R led to improved clinical outcomes and a low redislocation rate in patients with RPD and increased FAA. Additional D-DFO can achieve more favourable results in subjective function and patellar tracking than isolated MPFL-R in the setting of excessive FAA.

LEVEL OF EVIDENCE

Level IV.

Qualitative visual assessment of the J-sign demonstrates high inter-rater reliability

OBJECTIVES

To assess the inter- and intra-rater reliability of the classification of the J-sign as "large" versus "small or none" as compared to another two-level system ("present" versus "absent") and a three-level system ("large," "small," or "none") and to identify anatomical and patient factors associated with the presence of a large J-sign.

METHODS

Forty patients (40 knees) with recurrent patellar instability were prospectively enrolled and recorded on video actively extending their knee while seating. Four raters classified patellar tracking on two separate occasions using three systems: 1) two groups: J-sign versus no J-sign; 2) three groups: large J-sign, small J-sign, or no J-sign; and 3) two groups: large J-sign versus small or no J-sign. The intra- and inter-rater reliability of each system was assessed using kappa statistics. Anatomical (trochlear dysplasia, tibial tubercle-trochlear groove (TT-TG) distance, patellar height) and patient (Beighton score) factors as well as Knee Injury and Osteoarthritis Outcome Score (KOOS) subscales were compared between patients with a large J-sign and patients with a small or no J-sign.

RESULTS

Inter- and intra-rater reliability were found to be highest with the two-level classification system of a large J-sign versus a small or no J-sign (inter-rater kappa ​= ​0.76, intra-rater kappa ​= ​0.75). Patients with a large J-sign had more severe trochlear dysplasia as assessed with the sulcus angle (p ​= ​0.042) and were more likely to have a tight lateral retinaculum (p ​= ​0.032) and an elevated Beighton score (p ​= ​0.009). No significant differences in KOOS subscales were noted based on the presence of a large J-sign versus a small J-sign or no J-sign.

CONCLUSION

Qualitative visual assessment of patellar tracking with the J-sign demonstrates substantial inter- and intra-rater reliability, particularly when utilizing a two-group classification system to identify knees with a large J-sign. Patients with a large J-sign demonstrate an increased incidence of a tight lateral retinaculum, generalized ligamentous laxity, and trochlear dysplasia.

LEVEL OF EVIDENCE

Level III - cross-sectional study.

Physeal Sparing Approaches for MPFL Reconstruction

PURPOSE OF REVIEW

To update and concepts for pediatric physeal-sparing patellofemoral stabilization surgery.

RECENT FINDINGS

Recent studies have demonstrated positive results in patellofemoral stabilization in pediatric populations with physeal-sparing techniques that limit the potential for physeal damage. Comprehensive analysis remains limited by population and technique heterogeneity. Physeal-sparing patellofemoral stabilization, most significantly through physeal-sparing reconstruction of the medial patellofemoral ligament complex remains a viable option for pediatric patients with recurrent patellofemoral instability.

A modified Delphi consensus statement on patellar instability: part I

Aims

The aim of this study was to establish consensus statements on the diagnosis, nonoperative management, and indications, if any, for medial patellofemoral complex (MPFC) repair in patients with patellar instability, using the modified Delphi approach.

Methods

A total of 60 surgeons from 11 countries were invited to develop consensus statements based on their expertise in this area. They were assigned to one of seven working groups defined by subtopics of interest within patellar instability. Consensus was defined as achieving between 80% and 89% agreement, strong consensus was defined as between 90% and 99% agreement, and 100% agreement was considered to be unanimous.

Results

Of 27 questions and statements on patellar instability, three achieved unanimous consensus, 14 achieved strong consensus, five achieved consensus, and five did not achieve consensus.

Conclusion

The statements that reached unanimous consensus were that an assessment of physeal status is critical for paediatric patients with patellar instability. There was also unanimous consensus on early mobilization and resistance training following nonoperative management once there is no apprehension. The statements that did not achieve consensus were on the importance of immobilization of the knee, the use of orthobiologics in nonoperative management, the indications for MPFC repair, and whether a vastus medialis oblique advancement should be performed.

PROMIS physical function and pain perform poorly psychometrically in patients undergoing medial patellofemoral ligament reconstruction

PURPOSE

The purpose of this study was to assess the validity, floor and ceiling effects, and dimensionality of PROMIS Physical Function (PF) and Pain compared to legacy patient reported outcome (PRO) measures in patients undergoing medial patellofemoral ligament (MPFL) reconstruction.

METHODS

Patients who underwent MPFL reconstruction between 2018 to 2020 were retrospectively reviewed. Preoperatively, patients completed the IKDC, VR-12, Kujala, SF-12, KOOS JR, PROMIS PF and Pain surveys. Inter-survey convergence was assessed with Spearman correlations. Psychometric analysis included investigations of inter-survey convergent validity, intra-survey floor and ceiling effects, and Rasch analyses with person-item fit and iterative question elimination model fit testing.

RESULTS

A total of 76 patients (mean age: 22.6 ± 8.4 years) who completed preoperative surveys were included (compliance: 91.7-96.2%). Preoperatively, age was significantly associated with both PROMIS PF (coefficient:  - 0.291, P = 0.005) and Pain scores (coefficient: 0.294, P = 0.002). PROMIS PF had a Very Good correlation with IKDC and PROMIS Pain had a Very Good correlation with KOOS JR. Other correlations ranged from Poor to Good. No significant floor or ceiling effects were observed for any PRO. On iterative question elimination Rasch modelling, only two questions from PROMIS PF remained after 6 rounds of elimination while PROMIS Pain had no questions remaining after 3 rounds of elimination.

CONCLUSION

Preoperative PROMIS PF and Pain provided only Fair to Good correlations with most legacy PROs. Although no significant floor and ceiling effects were observed, PROMIS PF and Pain did not perform well psychometrically in this population of patients undergoing MPFL reconstruction. These results suggest PROMIS questionnaires should be used with caution in this population, especially if used in isolation, when discussing clinical expectations with patients. The authors recommend continued use of legacy PROs specific to assessment of patellar instability and function that have established validity in patellar instability populations.

LEVEL OF EVIDENCE

Level IV.

Patella alta and increased TT-TG distance do not adversely affect patient-reported outcomes following isolated MPFL reconstruction: A systematic review

OBJECTIVES

To analyze the effect of patellofemoral anatomical variations (patella alta, increased tibial tubercle-trochlear groove [TT-TG] distance, and trochlear dysplasia) on clinical outcomes after isolated medial patellofemoral ligament (MPFL) reconstruction.

METHODS

A comprehensive search from PubMed, Embase, and the Cochrane Library databases was conducted to identify studies that compared outcomes based on the presence or absence of patella alta, elevated tibial tubercle-trochlear groove (TT-TG) distance, and/or trochlear dysplasia. Exclusion criteria included reviews and meta-analyses, studies that included patients who underwent associated bony procedures, and those reporting outcomes after isolated MPFL reconstruction with no comparison between varying anatomical groups.

RESULTS

After application of selection criteria, 19 studies were included. Patella alta was not predictive of failure or poorer outcomes among 13 studies; however, 2 studies demonstrated poorer patient-reported outcome scores and/or higher failure rates with increasing patellar height. Increasing TT-TG distance demonstrated a statistically significant correlation with poorer outcomes in only one study, whereas 12 other studies showed no association. Trochlear dysplasia resulted in worse outcomes and greater failure rates in 6 studies, while 10 studies showed no statistically significant correlation between trochlear dysplasia and postoperative outcomes.

CONCLUSION

Patella alta and increased TT-TG distance did not adversely affect outcomes following isolated MPFL reconstruction in the preponderance of reviewed studies. Data are mixed regarding the impact of trochlear dysplasia on the outcomes of isolated MPFL reconstruction.

LEVEL OF EVIDENCE

IV.

Computer-aided design combined with 3D-printed osteotomy guide-assisted derotational distal femoral osteotomy for treating recurrent patellar dislocation with increased femoral anteversion angle: a retrospective study

PURPOSE

Derotational distal femoral osteotomy (DDFO) has good clinical outcomes for the treatment of the recurrent patellar dislocation combined with increased femoral anteversion angle (FAA). Currently, there is no uniform surgical technique. The purpose of this study was to evaluate the safety and efficacy of computer-aided design (CAD) combined 3D-printed osteotomy guide-assisted DDFO for treating these patients.

METHODS

In a retrospective study of 36 patients with recurrent patellar dislocation (RPD) from December 2017 to December 2020, all patients had increased FAA and underwent DDFO assisted by CAD combined with a 3D-printed osteotomy guide. Patients' radiological parameters were used to assess the correction of increased femoral torsion and preoperative and postoperative subjective scores were recorded to evaluate the knee function. Complications were recorded to determine the safety of the surgery.

RESULT

A total of 36 knees were included in this study, with a mean follow-up time of 32.6 ± 8.1 months. The mean age of the patients was 24.9±4.4 years and all patients experienced patellar dislocation preoperatively with a mean of 5.7±3.2 times. The patients' femoral anteversion angle decreased from 35.03±3.05° preoperatively to 14.80±0.87°, and the TT-TG distance decreased from 20.03±1.27 mm preoperatively to 19.22±1.22 mm. The hip-knee-ankle (HKA) angle and Insall-Salvatti index were not significantly different postoperatively compared to preoperatively. The knee function scores and visual analogue scale at the last follow-up were significantly improved compared to the preoperative scores. No major complications such as redislocation, nonunion, fixation or graft failure, or infection were observed in any patients.

CONCLUSION

Computer-aided design combined with 3D-printed osteotomy guide-assisted derotational distal femoral osteotomy could correct the increased anterior femoral torsion and demonstrate good results. There were no patients experienced re-dislocation during follow-up period and the overall complication rate is low.

Combined medial patellofemoral ligament and medial patellotibial ligament reconstruction in recurrent patellar instability: A systematic review and meta-analysis

BACKGROUND

The medial patellofemoral ligament (MPFL), along with the medial patellotibial ligament (MPTL) and medial patellomeniscal ligament, aid in the stabilization of the patellofemoral joint. Although the MPFL is the primary stabilizer and the MPTL is a secondary limiter, this ligament is critical in maintaining joint stability. There have been few studies on the combined MPFL and MPTL reconstruction and its benefits.

AIM

To look into the outcomes of combined MPFL and MPTL reconstruction in frequent patellar instability.

METHODS

By May 8, 2022, four electronic databases were searched: Medline (PubMed), Scopus, Web of Science, and Google Scholar. General keywords such as "patellar instability," "patellar dislocation," "MPFL," "medial patellofemoral ligament," "MPTL," and "medial patellotibial ligament" were co-searched to increase the sensitivity of the search.

RESULTS

The pooled effects of combined MPFL and MPTL reconstruction for Kujala score (12-mo follow-up) and Kujala score (24-mo follow-up) were positive and incremental, according to the findings of this meta-analysis. The mean difference between the Cincinnati scores was also positive, but not statistically significant. The combination of the two surgeries reduces pain. According to cumulative meta-analysis, the trend of pain reduction in various studies is declining over time.

CONCLUSION

The combined MPFL and MPTL reconstruction has good clinical results in knee function and, in addition to providing good control to maintain patellofemoral joint balance, the patient's pain level decreases over time, making it a valid surgical method for patella stabilization.

Outcomes After Derotational Distal Femoral Osteotomy for Recurrent Patellar Dislocations With Increased Femoral Anteversion: A Systematic Review and Meta-analysis

Background

An increased femoral anteversion angle (FAA) is a predisposing factor for recurrent patellar dislocations (RPDs), and combined procedures including derotational distal femoral osteotomy (DDFO) have been shown to be good options.

Purpose

To investigate the safety and effectiveness of combined DDFO on clinical and radiological outcomes to treat RPDs with an increased FAA.

Study Design

Systematic review; Level of evidence, 4.

Methods

This review was performed according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-analyses) guidelines. We searched 7 databases for articles from inception to March 10, 2023, that reported outcomes after combined DDFO in patients with an RPD and increased FAA. Two reviewers independently extracted data and assessed study quality. Outcomes evaluated were functional scores, redislocation rates, complications, satisfaction, and radiological parameters. A meta-analysis was performed to pool functional scores, with data reported as mean differences (MDs) and 95% confidence intervals (CIs).

Results

Included were 8 studies of 189 knees from 183 patients, with a mean patient age of 22.4 years and a mean follow-up of 33.4 months. The mean preoperative FAA ranged from 31° to 42.70°, and the mean postoperative FAA ranged from 10° to 19.08°. Significant improvements were found in the Kujala score (MD, 26.96 [95% CI, 23.54 to 30.37]), Lysholm score (MD, 26.17 [95% CI, 22.13 to 30.22]), visual analog scale score for pain (MD, -2.61 [95% CI, -3.12 to -2.10]), and Tegner activity score (MD, 1.33 [95% CI, 0.86 to 1.79]). No subluxation or redislocation occurred. The overall complication rate was 10.6%, and most of the complications were pain (60%) and limited knee activity (20%). The overall satisfaction rate was 83.3%. The patellar tilt angle significantly decreased from 40.7° ± 11.9° to 20.5° ± 8.7° and from 26.35° ± 6.86° to 11.65° ± 2.85° in 2 studies.

Conclusion

Combined DDFO was found to be safe and effective for the treatment of RPDs and an increased FAA by addressing both patellar dislocations and torsional malalignment. However, because of the lack of comparisons, it remains to be investigated when DDFO should be combined in such patients.

Medial patellofemoral ligament reconstruction in skeletally immature patients without correction of bony risk factors leads to acceptable outcomes but higher failure rates

OBJECTIVES

To report outcomes and re-dislocation rates of medial patellar stabilizers reconstruction without bone procedures for correction of anatomical risk factors for patellar instability in skeletally immature patients; to compare isolated medial patellofemoral ligament (MPFL) reconstruction to combined MPFL and medial patellotibial ligament (MPTL) reconstruction in this population.

METHODS

Patients with open physis and bone abnormalities including patella alta and/or increased tibial tubercle-trochlear groove (TT-TG) distance and/or trochlear dysplasia underwent MPFL reconstruction, either isolated or associated with MPTL reconstruction. Preoperative, 1-year follow-up and the latest follow-up (5 years minimum) data were collected. Radiological and clinical evaluations were conducted, with special attention to failure rate. Comparison of results from isolated MPFL and combined MPFL/MPTL reconstructions was performed.

RESULTS

Twenty-nine patients were included, 19 in the isolated MPFL group (median 14 years old; follow-up 5.8 ​± ​1.7 years) and 10 in the combined MPFL/MPTL group (median 13.5 years old; follow-up 5.2 ​± ​1.4 years). Kujala and Tegner scores increased over time, although without statistically significant differences between the two groups at the latest follow-up (p ​= ​0.840 and p ​> ​0.999, respectively). During follow-up, 5 of 19 (26.3%) isolated MPFL and 2 of 10 (20%) MPFL/MPTL reconstructions experienced recurrence of patellar dislocation (p ​> ​0.999). Trochlear dysplasia type D (p ​= ​0.028), knee rotation (p ​= ​0.009) and lateral patellar tilt angle (p ​= ​0.003) were associated with patellar instability recurrence. The isolated MPFL group showed increased laxity on physical exam at the latest follow-up compared to the 1-year follow-up (patellar glide test (p ​= ​0.002), patellar tilt test (p ​= ​0.042) and subluxation in extension (p ​= ​0.019). This increased laxity was not observed in the MPFL/MPTL group (p ​> ​0.999). Comparing both groups, the glide test was significantly better in the combined MPFL/MPTL group in comparison to the isolated MPFL reconstruction group at the latest follow-up (p ​= ​0.021).

CONCLUSION

MPFL reconstruction in isolation or combined with MPTL reconstruction in skeletally immature patients with additional uncorrected anatomical patellofemoral abnormalities leads to acceptable clinical outcomes within a minimum of 5 years follow-up, although has a high failure rate of 24.1%. Addition of a MPTL reconstruction to the MPFL may result in decreased patellar laxity on physical exams, as demonstrated by better patellar glide test, patellar tilt test and subluxation in extension.

LEVEL OF EVIDENCE

Level III; retrospective cohort study.

Concomitant anterior medializing osteotomy and MPFL reconstruction improves patellar tilt when compared to MPFL reconstruction alone

PURPOSE

Understanding how surgical procedures influence anatomic factors associated with patellofemoral instability can help guide surgeons when planning treatments for individual patients. This study sought to understand how patellar tilt is affected in adolescent patients with elevated pre-operative tibial tuberosity to trochlear groove (TT-TG) values undergoing medial patellofemoral ligament reconstruction (MPFLR) with or without an anterior medializing osteotomy (AMZ).

METHODS

Utilizing a prospective database of 274 patellofemoral instability patients who underwent MPFLR ± AMZ by one of two orthopedic surgeons at a single institution, those who underwent MPFLR + AMZ were identified. Pre-operative and post-operative magnetic resonance imaging (MRI) were used to measure TT-TG distance, while radiographs were used to measure patellar tilt (tilt). Patients were matched based on age at surgery (within 2 years) and pre-operative TT-TG distance (within 2 mm) to a comparison cohort of patients who underwent isolated MPFLR (iMPFLR) without osseous procedures.

RESULTS

A total of 56 patients were analyzed (28 per group). The mean age of the cohort was 15.5 ± 2.0 years and was similar between both groups (15.9 ± 1.9 versus 15.1 ± 2.0 years [n.s]). When comparing the two cohorts, significant pre- to post-operative decreases in patellar tilt for both MPFLR + AMZ (6.6 degrees, p < 0.001) and iMPFLR (3.9 degrees, p = 0.013) were noted. While there were no differences in pre-operative patellar tilt (21.2 ± 3.5 versus 21.1 ± 3.4 [n.s]), post-operatively, MPFLR + AMZ had significantly less patellar tilt than iMPFLR (13.2 ± 5.5 versus 16.5 ± 4.4, p = 0.017).

CONCLUSIONS

This study found that patellar tilt significantly improved in participants undergoing either MPFLR + AMZ or iMPFLR. In addition, those undergoing MPFLR + AMZ were found to have significantly lower post-operative tilt than those undergoing iMPFLR. If patellar tilt is found pre-operatively to be significantly elevated and a risk for future dislocations, these findings suggest that surgeons might strongly consider MPFLR with AMZ to further address the increased tilt.

LEVEL OF EVIDENCE

III.

Redefining Trochlear Dysplasia: Normal Thresholds Vary by Measurement Technique, Landmarks, and Sex

BACKGROUND

Trochlear dysplasia is a known risk factor for patellar instability. Multiple radiographic measurements exist to assess trochlear morphology, but the optimal measurement technique and threshold for instability are unknown.

PURPOSE

To describe the optimal measurements and thresholds for trochlear dysplasia on magnetic resonance imaging (MRI) that can identify knees with patellar instability in male and female patients.

STUDY DESIGN

Cohort study (diagnosis); Level of evidence, 3.

METHODS

Knee MRI scans of patients with patellar instability were compared with those of age- and sex-matched controls. Measurements of the sulcus angle, lateral trochlear inclination (LTI), and trochlear depth were performed on axial images using bony and cartilaginous landmarks. Receiver operating characteristic curve analysis was performed, with the area under the curve (AUC) describing the accuracy of each diagnostic test. Optimal cutoff values were calculated to distinguish between knees with and without patellar instability. AUC and cutoff values were reported for each measurement as well as for male and female subgroups.

RESULTS

A total of 238 knee MRI scans were included in this study (138 female, 100 male; age range, 18-39 years). Trochlear depth measurements had the greatest diagnostic value, with AUCs of 0.79 and 0.82 on bone and cartilage, respectively. All measurements (sulcus angle, LTI, trochlear depth) on bone and cartilage had an AUC ≥0.7 (range, 0.70-0.86), with optimal cutoff values of 145° (bone) and 154° (cartilage) for the sulcus angle, 17° (bone) and 13° (cartilage) for LTI, and 4 mm (bone) and 3 mm (cartilage) for trochlear depth. Optimal cutoff values in female patients varied from those in male patients for all measurements except for cartilaginous trochlear depth.

CONCLUSION

Normal thresholds for trochlear dysplasia varied based on the use of bony versus cartilaginous landmarks. Cartilaginous trochlear depth measurements had the greatest ability to identify knees with patellar instability. Furthermore, optimal cutoff values for all measurements except for cartilaginous trochlear depth differed between female and male patients. These findings suggest that sex-specific parameters of normal values may be needed in the assessment of risk factors for patellofemoral instability.

Preoperative Patella Alta on Caton-Deschamps Index Is a Predictor of Outcome Following Isolated Medial Patellofemoral Ligament Reconstruction

Purpose

The purpose of this study was to determine whether a preoperative Caton-Deschamps index (CDI) ≥ 1.30, as measured by magnetic resonance imaging, is associated with rates of postoperative instability, revision knee surgery, and patient-reported outcomes in patients undergoing isolated medial patellofemoral ligament (MPFL) reconstruction.

Methods

Patients who underwent primary medial patellofemoral ligament reconstruction (MPFLR) between 2015 and 2019 at a single institution were assessed. Only those with at least 2 year follow up were included. Patients who had undergone a previous ipsilateral knee surgery, concomitant tibial tubercle osteotomy and/or ligamentous repair/reconstruction at the time of MPFL reconstruction were excluded from the study. CDIs were evaluated by three investigators based on magnetic resonance imaging measurement. Patients with a CDI ≥ 1.30 were included in the patella alta group, while those with a CDI between 0.70 and 1.29 served as controls. A retrospective review of clinical notes was used to evaluate the number of postoperative instability episodes and revisions. Functional outcomes were measured by the International Knee Documentation Committee (IKDC) and 12-Item Short Form Health Survey (SF-12) physical and mental scores.

Results

Overall, 49 patients (50 knees, 29 males, 59.2%) underwent isolated MPFLR. Nineteen (38.8%) patients had a CDI ≥ 1.30 (mean: 1.41, range: 1.30-1.66). The patella alta group was significantly more likely to experience a postoperative instability episode (36.8% vs 10.0%; P = .023) and was more likely to return to the operating room for any reason (26.3% vs 3.0%; P = .022) compared to those with normal patellar height. Despite this, the patella alta group had significantly greater postoperative IKDC (86.5 vs 72.4; P = .035) and SF-12 physical (54.2 vs 46.5; P = .006) scores. Pearson's correlation showed a significant association between CDI and postoperative IKDC (R ² = 0.157; P = .022) and SF-12P (R ² = .246; P = .002) scores. There was no difference in postoperative Lysholm (87.9 vs 85.1; P = .531). and SF-12M (48.9 vs 52.5; P = .425) scores between the groups.

Conclusion

Patients with preoperative patella alta, as measured by CDI had higher rates of postoperative instability and return to the OR with isolated MPFL reconstruction for patellar instability. Despite this, higher preoperative CDI was associated with greater postoperative IKDC scores and SF-12 physical scores in these patients.

Level of Evidence

Retrospective cohort study, Level IV.

Patient-Reported Outcomes and Risk Factors for Decreased Improvement after Patellofemoral Arthroplasty

Patellofemoral arthroplasty (PFA) is acknowledged as the method for the treatment of isolated patellofemoral osteoarthritis (PFOA). Few previous studies have assessed the patient-reported outcomes (PROs) and risk factors of less improvement of PROs in patients undergoing PFA. A retrospective analysis was performed, including all patients who had undergone PFA. Pre- and postoperative PROs included the Oxford Knee Score (OKS) and Kujala score. Univariate and multivariate statistical analyses were performed to assess influencing factors of less improvement of PROs including the demographic factors (gender, age, body mass index, smoking, opioid usage, and duration of symptoms [DOSs]), surgical factors (concomitant surgery), and imaging factors (trochlear dysplasia [TD], patellar height, the degree of PFOA). A total of 46 PFAs were analyzed with a mean follow-up of 37 ± 7 months. The mean age at surgery was 61.1 ± 7.7 years. Patients showed significant improvement in all PROs (p < 0.001). Patients with TD preoperatively have greater improvement in OKS and Kujala score postoperatively (19.2 ± 5.0 vs. 23.1 ± 3.6, p = 0.038). Longer DOSs (≥1 year) had a greater mean improvement in OKS and Kujala score (p = 0.011 and p = 0.000). According to the measurement of patella height, patients with patella alta (Caton-Deschamps index [CDI] ≥1.3) showed less improvement in both OKS and Kujala score (p = 0.000 and p = 0.002). PFA is a safe and efficient surgery with good PROs. Patella alta with a CDI ≥1.3 and duration of preoperative symptoms ≤ 1 year were risk factors for decreased OKS and Kujala score improvement, while the preoperative presence of TD was significantly predictive factors for increased OKS improvement.

Complication Rates After Medial Patellofemoral Ligament Reconstruction Range From 0% to 32% With 0% to 11% Recurrent Instability: A Systematic Review

PURPOSE

To review the incidence of complications following primary medial patellofemoral ligament (MPFL) reconstruction for recurrent patellar instability.

METHODS

A literature search was conducted by querying PubMed and Scopus databases from database inception through August 2022 according to the 2020 Preferred Reporting Items for Systematic Review and Meta-analysis guidelines using the terms "Medial Patellofemoral Ligament," "MPFL," "reconstruction," "patellar," and "instability." Inclusion criteria included studies reporting complications following primary MPFL reconstruction for recurrent patellar instability. Exclusion criteria consisted of studies reporting on patients undergoing concurrent osteotomy procedures, revision reconstruction, and biomechanical or anatomic studies. The incidence of specific complications was aggregated from the included studies.

RESULTS

Twenty-eight studies, consisting of 1,478 patients (n = 1521 knees), with a mean age of 23.3 years (mean range, 19-34.3 years) were identified. The overall incidence of complications ranged from 0% to 32.3% of knees. Failure ranged from 0% to 10.7% of knees, whereas patellar fractures occurred in 0% to 8.3% of knees, primarily in patients treated with full-length transverse tunnel or 2-tunnel techniques. All patellar fractures occurred in patients with patellar tunnels ranging from 4.5 to 6.0 mm in diameter. The incidence of postoperative knee stiffness/range of motion deficit ranged from 0% to 20%. Persistent anterior knee pain, ranged from 0% to 32.3%.

CONCLUSIONS

Complications following primary MPFL reconstruction ranged from 0% to 32.3% of knees, primarily consisting of residual anterior knee pain. Failure ranged from 0% to 10.7% of knees, whereas patellar fractures were reported in 0% to 8.3% of knees. Fractures primarily occurred with a full-length transverse tunnel or 2-tunnel techniques, whereas all fractures occurred with patellar tunnels ranging from 4.5 mm to 6.0 mm in diameter.

LEVEL OF EVIDENCE

IV; Systematic Review of Level I-IV studies.

A preliminary study of proximal realignment combination surgery in the treatment of adolescent habitual patellar dislocation

OBJECTIVE

A combination of lateral soft tissue release, medial soft tissue contraction, vastus medialis anterior placement, medial patellofemoral ligament reconstruction, and rectus femoris insertion reconstruction are introduced in the treatment of habitual patellar dislocation in adolescents.

METHODS

A retrospective analysis was performed on 12 patients (17 knees) with habitual patellar dislocation and unclosed epiphyses who underwent surgical treatment at the First Hospital of Jilin University from May 2017 to November 2021. The Lysholm scores and Q angle were collected preoperatively and at final follow-up and were compared.

RESULTS

Twelve patients (4 boys and 8 girls) aged 10-15 years were retrospectively analysed, who followed up for an average of 21 months (5-48 months). The range of motion of the knee joint returned to normal in all patients, and no cases of complications including surgical site infection, joint stiffness, or patellar re-dislocation occurred. The mean Lysholm scores and Q angles improved from 73.9, and 19.6° preoperatively to 91.7, and 13.9° at the final follow-up, respectively.

CONCLUSION

The preliminary effect of the combination surgery for habitual patellar dislocation in adolescents was satisfactory.

At 10-Year Minimum Follow-Up, One-Third of Patients Have Patellofemoral Arthritis After Isolated Medial Patellofemoral Ligament Reconstruction Using Gracilis Tendon Autograft

PURPOSE

To report the long-term clinical outcomes after isolated medial patellofemoral ligament reconstruction (MPFLr) to treat recurrent patellar instability.

METHODS

This was a single-center study of patients undergoing an isolated MPFLr between 2000 and 2011. All patients underwent reconstruction using hamstring autograft. The inclusion criteria were a minimum 10-year follow-up period and skeletally mature patients with more than 1 episode of patellar dislocation who underwent MPFLr without an associated bony procedure.

RESULTS

A total of 54 knees were available for final analysis. The mean follow-up period was 12.3 years (range, 10-14 year). The mean age at surgery was 25 years. No patients had patellofemoral arthritis (PFA) prior to surgery. Preoperatively, the mean Caton-Deschamps index was 1.1 and the mean tibial tubercle-trochlear groove distance was 14.9 ± 2 mm (range, 7-17 mm). All patients had trochlear dysplasia according to the Dejour classification. At final follow-up, the mean Kujala score was 82.9 ± 15.3; mean International Knee Documentation Committee score, 78.3 ± 18.5; and mean Tegner score, 4.0 ± 1.7. Patients with an unsatisfactory outcome as determined by a Kujala score lower than 80 had a higher Caton-Deschamps index preoperatively and were more likely to be female patients; however, neither factor reached significance. Of the patients, 33 (66%) had no radiographic evidence of PFA whereas 15 (30%) had Iwano stage 1 and 2 had Iwano stage 2 (4%). At final follow-up, 4 patients (7.4%) had recurrent instability requiring revision surgery.

CONCLUSIONS

Isolated MPFLr with gracilis tendon autograft in appropriately selected patients is an effective long-term treatment for recurrent patellofemoral instability with low rates of recurrence. One-third of patients exhibit radiographic evidence of PFA more than 10 years after isolated MPFLr.

LEVEL OF EVIDENCE

Level IV, case series.

What is the J-sign and why is it important?

PURPOSE OF REVIEW

Recurrent lateral patellofemoral instability is a complex condition that requires a thorough evaluation to optimize treatment. The J-sign test is classically part of the physical examination, but its significance and importance remain unclear. This review aims to describe how to perform the test and classify the observation as well as to analyze the most recent literature on its clinical applications.

RECENT FINDINGS

The J-sign test has been described as positive (present) or negative (absent), and classified using the quadrant method and the Donnell classification. Suboptimal inter-rater reliability has been shown for both classifications, making comparison between clinicians and studies challenging. The J-sign is most predominantly associated with patella alta, trochlear dysplasia, lateral force vector, and rotational abnormalities. A growing number of studies have shown a correlation between a positive J-sign and lower clinical outcome scores and higher rate of surgical failure.

SUMMARY

The J-sign is an important aspect of the physical examination in patients with recurrent lateral patellofemoral instability. Although there is no consensus on how to perform or classify the test, it can be used as a marker of severity of patellofemoral instability and is one of the tools available to guide the treatment plan.

Failure of isolated medial patellofemoral ligament reconstruction in children: Risk factors and management

Background

Patellofemoral instability is a frequent cause of referral in pediatric sports medicine. Isolated medial patellofemoral ligament reconstruction is widely used and provides satisfactory outcomes with a low failure rate. Given the success of this surgical technique, the literature on medial patellofemoral ligament reconstruction failures in the pediatric population is limited. Moreover, given the multifactorial nature of patellofemoral instability, the heterogeneity of the current literature, and the paucity of pediatric studies, medial patellofemoral ligament reconstruction failures are often difficult to analyze.

Methods

The purpose of this study was to retrospectively review the associated risk factors, surgical management, and the clinical outcomes at 2-year follow-up of skeletally immature patients that presented to our clinic with a failed medial patellofemoral ligament reconstruction.

Results

Of the 181 cases in 155 patients included in this study, treatment failed in 12 (7%). All 12 patients presented with at least one risk factor for patellofemoral instability, the most common being trochlear dysplasia and a high-grade J sign.

Conclusions

We conclude that isolated medial patellofemoral ligament reconstruction for patellofemoral instability in children has a low failure rate. Clinicians must assess pre-operative risk factors before surgical treatment is considered. A high-grade J sign and high-grade trochlear dysplasia were associated with medial patellofemoral ligament reconstruction failure in this cohort. Tailoring treatment to patients' associated risk factors selection may improve outcomes.

When Should Bony Correction Be Considered in Addition to Medial Patellofemoral Ligament Reconstruction? Results of a Clinically Derived 2-Group Classification of Lateral Patellar Instability Based on 122 Patients at 2- to 5-Year Follow-up

Background

The need for concomitant bony procedures to realign pathoanatomic risk factors in addition to medial patellofemoral ligament reconstruction (MPFL-R) remains unclear.

Purpose

To evaluate a clinically derived 2-part classification of lateral patellar instability aimed at identifying patients indicated for a concomitant bony procedure.

Study Design

Cohort study; Level of evidence, 3.

Methods

The study included 122 patients (42 male, 80 female; mean ± SD age, 22 ± 6 years) who were assigned to a mild instability group (mIG) and a complex instability group (cIG) based on the reversed dynamic patellar apprehension test (ReDPAT) and J-sign. The mIG had a positive ReDPAT result <40° to 50° of knee flexion and an absent or low-grade J-sign (grade 1), and the cIG had a positive ReDPAT result >40° of knee flexion and/or a high-grade J-sign (grade 2 or 3). The mIG underwent isolated MPFL-R, and the cIG underwent MPFL-R and concomitant bony procedures depending on the established risk factor assessment. For evaluation, the BANFF Patellar Instability Instrument 2.0 (BPII 2.0) and numeric analog scale (0-10) for patellofemoral pain and subjective knee function were used. The minimal clinically important difference for the BPII 2.0 was ascertained by calculating half the standard deviation of baseline scores.

Results

Radiographic analysis confirmed a significantly more pronounced pathoanatomic risk factor constellation in the cIG regarding severity of trochlear dysplasia, distal malalignment, and patellar height (all P < .05). At final follow-up, no patellar redislocation occurred in either group; 2 patients in the cIG reported patellar subluxation. Within both groups, all outcome scores improved significantly pre- to postoperatively (all P < .0001); no between-group difference was found regarding BPII 2.0 score and numeric analog scale for function. The minimal clinically important difference for the BPII 2.0 was met by 84% (32/38) of the mIG and 90% (76/84) of the cIG (P = .36), but the cIG experienced more patellofemoral pain than the mIG (1.3 ± 1.6 vs 2.1 ± 2.1; P = .036).

Conclusion

Patients with a high-grade J-sign and/or a positive ReDPAT finding beyond 40° to 50° of knee flexion exhibited a significantly more pronounced pathoanatomic risk factor constellation; however, the correction of modifiable risk factors led to similarly good outcomes to patients who underwent isolated MPFL-R. A slightly higher level of patellofemoral pain after bony procedures was evident in these patients.

The remaining parameters of patellar instability could be affected for osteoarthritic change after medial patellofemoral ligament reconstruction with or without anteromedialization of the tibial tubercle osteotomy for patellar instability: a retrospective cohort study

BACKGROUND

In literature, studies evaluating the factors associated the postoperative progression of patellofemoral (PF) osteoarthritis (OA) following patellar stabilization surgery are limited. This study aimed to compare the clinical outcomes after medial patellofemoral ligament reconstruction (MPFLR) as an isolated procedure (iMPFLR) and in combination with anteromedialization (AMZ) of the tibial tubercle osteotomy (TTO) and investigate the factors related to the postoperative progression of PFOA after patellar stabilization surgery.

METHODS

Between 2009 and 2020, 30 knees of 23 consecutive patients underwent MPFLR with or without AMZ, using an autologous semitendinosus tendon graft; they were followed up for more than 2 years in the retrospective nature of the study. iMPFLR was performed in cases of recurrent patellar dislocation with normal tibial tubercle-trochlear groove (TT-TG) distance and no PFOA, and MPFLR+AMZ was performed for cases of excessive TT-TG distance, preoperative PFOA of recurrent patellar dislocation, or habitual patellar dislocation. Clinical findings and radiographs of the PF joint were evaluated pre- and postoperatively with PF alignment parameters and PFOA and were compared between surgical procedures. Factors for the postoperative progression of PFOA were compared between the OA progression and non-progression groups.

RESULTS

Postoperative clinical score, radiographic parameters except for sulcus angle, TT-TG distance, and progression of PFOA were not significantly different between the iMPFLR and MPFLR+AMZ groups. Postoperative lateral patellar displacement (p = 0.001) and congruence angle (p = 0.017) were significantly different between the OA progression and non-progression groups.

CONCLUSION

Similar to MPFLR for recurrent cases, MPFLR with AMZ can improve the clinical and radiographic outcomes in severe cases. The remaining parameters of patellar instability could be affected in the postoperative progression of PFOA after MPFL reconstruction with or without AMZ of TTO for patellar instability.

Comparison of patellar anchor fixation graft and graft through patellar tunnel reconstruction of medial patellofemoral ligament in the treatment of recurrent patellar dislocation: A protocol for a meta-analysis of comparative studies

BACKGROUND

Recurrent patellar dislocation (RPD) occurs in people who have their own patellofemoral dysplasia and who have not been properly treated after their first patellar dislocation. For RPD where conservative treatment is ineffective, medial patellofemoral ligament (MPFL) reconstruction is the first choice for surgical treatment, but there are various and controversial ways of MPFL reconstruction and fixation. Initially, more scholars adopted the patellar lateral tunneling (PT) approach to contain and stabilize the graft, but with the newer materials and techniques, some experts adopted the lateral patellar anchor fixation (AF) of the graft, which can avoid the collateral damage caused by the patellar lateral tunneling and can obtain the same definite efficacy. Therefore, a meta-analysis must be performed to provide evidence whether there is a difference between AF and PT reconstruction of the MPFL in the treatment of RPD.

METHODS

We will search, with no time restriction, without any restriction of language and status, the time from the establishment of the database to October 2022, on the following databases: PubMed (MEDLINE), Cochrane Central Register of Controlled Trials (CENTRAL), Web of Science, Chinese National Knowledge Infrastructure (CNKI), Wanfang Data (WF), Chinese Scientific Journals Database (VIP), and Chinese databases SinoMed (CBM) electronic databases. The electronic database search will be supplemented by a manual search of the reference lists of included articles. We will apply the risk-of-bias tool of the Cochrane Collaboration for randomized controlled trials to assess the methodological quality. Risk-of-Bias Assessment Tool for Non-randomized Studies was used to evaluate the quality of comparative studies. Statistical analysis will be conducted using RevMan 5.4 software.

RESULTS

This systematic review and meta-analysis will evaluate the functional outcomes of the two fixation modalities, AF and PT, in reconstructing MPFL for RPD.

CONCLUSION

The findings of this study will provide a basis for clinical judgment of whether there is a difference between the two forms of AF and PT reconstructed MPFL for RPD.

A Novel Technique of Arthroscopic Femoral Tunnel Placement during Medial Patellofemoral Ligament Reconstruction for Recurrent Patellar Dislocation

Recurrent patellar dislocation is a commonly encountered patellofemoral disease. Prompt surgical intervention is indicated for recurrent dislocation to restore patellofemoral stability. As one of the most preferred procedures, medial patellofemoral ligament (MPFL) reconstruction has been implemented on a large scale. Femoral tunnel placement remains a crucial technical issue during MPFL reconstruction and is critical to ensure the isometry and proper tension of the graft. Currently, visual-palpatory anatomic landmarks and fluoroscopy-guided radiographic landmarks comprise the main approaches to intraoperative femoral tunnel positioning. However, the accuracy of both methods has been questioned. This article introduces an arthroscopic femoral tunnel placement technique. Apart from traditional anteromedial and anterolateral portals, two auxiliary arthroscopic portals are specially designed. The adductor tubercle, the medial epicondyle and the posterior edge are selected as main anatomic landmarks and are directly visualized in sequence under arthroscope. The relative position between the femoral attachment of the MPFL and the three landmarks is measured on preoperative three-dimensional computed tomography, providing semi-quantified reference for intraoperative localization. This technique achieves minimally invasive tunnel placement without X-ray exposure, and especially suits obese patients for whom palpatory methods are difficult to perform.

Arthroscopic Anatomical Double-Bundle Medial Patellofemoral Complex Reconstruction Improves Clinical Outcomes in Treating Recurrent Patellar Dislocation Despite Trochlear Dysplasia, Elevated Tibial Tubercle-Trochlear Groove Distance, and Patellar Alta

PURPOSE

To evaluate the clinical outcomes of arthroscopically assisted double-bundle medial patellofemoral complex reconstruction (MPFC-R).

METHODS

A retrospective review was carried out among adult patients who experienced at least 2 patellar dislocations and underwent primary arthroscopically assisted MPFC-R between January 2014 and November 2019. Dejour classification, tibial tubercle-trochlear groove (TT-TG) distance, and patellar height (with Insall-Salvati index) were measured. Pre- and postoperative patellar tilt were compared. Information on outcome scores, ability to return to sports, postoperative recurrent dislocations, and complications was recorded.

RESULTS

A total of 42 MPFC-Rs in 39 patients were included. Mean age at surgery was 22.2 ± 7.6 years; 69.2% of patients were female. Mean follow-up was 47.3 ± 20.2 months. Seventy-four percent of cases had Dejour B (19.0%), C (33.3%), and D (21.4%) trochlear dysplasia; mean TT-TG distance was 19.6 ± 3.5 mm, and mean Insall-Salvati index was 1.21 ± 0.17. Mean patellar tilt decreased from 27.6 ± 11.6° to 9.4 ± 6.5° (P < .001). All patients had statistically significant (P < .001) improvement in mean International Knee Documentation Committee (IKDC) (44.9 ± 18.2 to 87.5 ± 6.9), Lysholm (61.4 ± 16.6 to 94.1 ± 6.4), Kujala (56.0 ± 16.8 to 92.9 ± 5.3), and Tegner score (2.7 ± 1.3 to 4.6 ± 1.4). The majority of patients (96.9%) returned to sports, with 90.3% returning to the same or greater level of activity. No postoperative dislocations or subluxations were reported.

CONCLUSIONS

Arthroscopically assisted double-bundle MPFC-R is a promising procedure to treat recurrent patellar instability at 2- to 7-year mid-term follow-up, despite the presence of trochlear dysplasia, elevated TT-TG distance and patellar alta. The improvement of IKDC score exceeded the minimal clinically important difference in 95.2% patients, and 66.7% surpassed the patient acceptable symptomatic state based on postoperative IKDC score with no redislocations being reported at latest follow-up.

LEVEL OF EVIDENCE

Level IV, case series, retrospective.

Medial patellofemoral ligament reconstruction using a digital tensiometer to determine graft tension: Surgical technique and mid-term follow-up

PURPOSE

The optimal method for achieving proper graft tension during patellofemoral ligament reconstruction is a topic of debate. In the past, a digital tensiometer was used to simulate the knee structure, and a tension of approximately 2N was identified as suitable for restoring the patellofemoral track. However, it is unclear whether this tension level is sufficient during the actual surgery. The objective of this study was to verify the efficacy of graft tension using a digital tensiometer for medial patellofemoral ligament (MPFL) reconstruction and to conduct a mid-term follow-up.

METHODS

The study enrolled 39 patients who had experienced recurrent patellar dislocation. Preoperative computed tomography scans and X-rays confirmed patellar instability, patellar tilt angle patellar congruence angle and the history of dislocation and patellar apprehension test. Knee function was evaluated using preoperative and postoperative Lysholm and Kujala scores.

RESULTS

The study included 39 knees, comprising 22 females and 17 males, with an average age of 21.10 ± 7.26. The patients were followed up for at least 24 months through telephone or face-to-face questionnaires. All patients had a preoperative history of ≥2 patellar dislocations, none of which were surgically treated. During surgery, all patients underwent isolated MPFL reconstruction and lateral retinacula release. The mean Kujala and Lysholm scores were 91.28 ± 4.90 and 90.67 ± 5.15, respectively. The mean PTA and PCA were 11.5 ± 2.63 and 2.38 ± 3.58, respectively. The study found that a tension of approximately 27.39 ± 5.57N (14.3-33.5N) was required to restore the patellofemoral track in patients with recurrent patellar dislocation. No patients required reoperation during the follow-up period. Overall, 36 out of 39 patients (92.31%) reported no pain when completing daily activities at the last follow-up.

CONCLUSION

In conclusion, a tension level of approximately 27.39 ± 5.57N is necessary to restore normal patellofemoral relationships during clinical practice, which indicates that using a tension of 2N is too low. The use of a tensiometer during patellofemoral ligament reconstruction is a more accurate and reliable surgical procedure for treating recurrent patellar dislocation.

After MPFL reconstruction, femoral tunnel widening and migration increase with poor tunnel positioning and are related to poor clinical outcomes

PURPOSE

Isolated MPFL reconstruction (iMPFLR) is increasingly used for the surgical treatment of treatment for recurrent patella dislocation. The purpose of this study was to evaluate the influence of tunnel widening and migration on clinical outcomes after iMPFL using a CT-scannographic analysis at 6 months postoperatively.

METHODS

One hundred and sixty patients (91 females for 69 males) with an average age of 23 years [14-54] who underwent iMPFLR and had an evaluation scan at 6 months postoperatively were evaluated with a mean follow-up of 97 ± 89 months [12 to 166]. Functional International Knee Documentation Committee (IKDC) Score, Kujala score, and joint mobility were assessed preoperatively, at 6 months and at the latest follow-up. The IKDC and Kujala scores were expressed as the difference between pre- and postoperative scores (dIKDC and dKujala). The position of the femoral tunnel was assessed according to the Schöttle criteria on post-operative radiographic profiles. Tunnel widening (at three levels of measurement) and the migration of the center of the tunnel were studied on a CT-scan analysis at 6 months. Any correlation and regression between the evolution of the clinical scores and the measured scannographic parameters were investigated. The relationships between tunnel position and tunnel changes were also studied.

RESULTS

Between pre- and post-op, the IKDC (45 ± 13 to 80 ± 15, p < 0.001) and Kujala (55 ± 11 to 87 ± 12, p < 0.001) scores were significantly improved. Patients with tunnel changes had decreased clinical and functional results at 6 months post-op of an iMPFLR (p < 0.001). These changes in the femoral tunnel, evidenced by a tunnel entrance widening and migration of the tunnel center, were related to an initial malposition of the tunnel (p < 0.001).

CONCLUSION

In iMPFLR, changes in the femoral tunnel, corresponding to dilatation and migration of the tunnel center, may occur. These changes are increased by the initial malpositioning of the femoral tunnel and are correlated with less good clinical and functional outcomes.

LEVEL OF EVIDENCE

Level IV.

Patient-Reported Outcomes Following Medial Patellofemoral Reconstruction With Peroneus Longus Allografts Demonstrate Good Results

Purpose

To evaluate the recurrent dislocation risk and patient-reported outcomes of peroneus longus allograft tissue for medial patellofemoral ligament (MPFL) reconstruction.

Methods

Patients who underwent MPFL reconstruction with peroneus longus allograft at an academic center between 2008 and 2016 were identified. Record review and patient contact were used to identify any cases of recurrent patellar dislocation and collect patient-reported outcomes scores (Knee injury and Osteoarthritis Outcome Score [KOOS], Norwich Patellar Instability score, Marx activity scale). Patients with 1-year minimum follow-up were included. Outcomes were quantified and the proportion of patients reaching a previously defined patient acceptable symptom state (PASS) for patellar instability was determined.

Results

Sixty-one patients (42 female and 19 male) underwent MPFL reconstruction with peroneus longus allograft during the study period. Forty-six patients (76%) with 1-year minimum follow up were contacted at a mean of 3.5 years postoperative. The mean age at time of surgery was 22 ± 7.2 years. Patient-reported outcomes data were available in 34 patients. Mean KOOS subscale scores were as follows: Symptoms 83.2 ± 19.1, Pain 85.2 ± 17.6, Activities of Daily Living 89.9 ± 14.8, Sports 75 ± 26.2, and Quality of Life 72.6 ± 25.7. The mean Norwich Patellar Instability score was 14.9% ± 17.4%. The mean Marx activity score was 6.0 ± 5.2. No recurrent dislocations were noted during the study period. Sixty-three percent of patients who underwent isolated MPFL reconstruction met PASS thresholds in at least 4 of 5 KOOS subscales.

Conclusions

The use of a peroneus longus allograft in MPFL reconstruction in conjunction with other indicated procedures results in a low re-dislocation risk and a high proportion of patients meeting PASS criteria for patient-reported outcome scores 3 to 4 years postoperatively.

Level of Evidence

IV, case series.

Predictors of Graft Failure After Primary Medial Patellofemoral Ligament Reconstruction

BACKGROUND

The tibiofemoral rotation angle has been found to be higher in patients with recurrent patellar dislocations (RPDs) than in healthy people; however, little is known about the clinical significance of this finding.

PURPOSE

To determine whether an increased tibiofemoral rotation angle is associated with graft failure after primary medial patellofemoral ligament reconstruction (MPFL-R) and to investigate the role of the tibiofemoral rotation angle in predicting MPFL-R failure in patients with RPDs.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

We retrospectively analyzed the records of 632 consecutive patients with clinically diagnosed RPDs from 2011 to 2018. Postoperative stress radiography of the patellofemoral joint was performed to identify whether the graft failed. After a review, 33 patients who showed MPFL-R failure were allocated to the failure group. They were matched 1:2 to 66 participants who underwent successful MPFL-R (control group). The cutoff value and area under the curve (AUC) of the tibiofemoral rotation angle for predicting graft failure after primary MPFL-R were determined, and the risk factors for MPFL-R failure were assessed by multivariate logistic regression analysis.

RESULTS

The tibiofemoral rotation angle was significantly higher in the failure group than in the control group (16.4° ± 5.6° vs 6.4° ± 4.5°, respectively; P < .001). The cutoff value of the tibiofemoral rotation angle for predicting graft failure was 12.3° (sensitivity, 81.8%; specificity, 89.4%; AUC, 0.920). Overall, 3 risk factors for MPFL-R failure were determined: excessive tibiofemoral rotation (≥12.3°) (odds ratio [OR], 13.159 [95% CI, 2.469-70.139]; P = .003), a preoperative high-grade J-sign (OR, 7.674 [95% CI, 1.232-47.809]; P = .029), and a femoral tunnel malposition (OR, 6.976 [95% CI, 1.077-45.187]; P = .042).

CONCLUSION

In this study, excessive tibiofemoral rotation, a preoperative high-grade J-sign, and a femoral tunnel malposition were identified as risk factors for graft failure after primary MPFL-R in patients with RPDs. More importantly, excessive tibiofemoral rotation ( ≥ 12.3°) may predict the failure of primary MPFL-R, which can help surgeons easily identify high-risk patients of MPFL-R failure before surgery.

Reconstruction of the medial patellofemoral ligament with nonresorbable suture tape normalizes patellar maltracking independent of patella-side fixation technique

PURPOSE

Patellar maltracking caused by a rupture of the medial patellofemoral ligament (MPFL) can be improved by MPFL reconstruction (MPFL-R) with a tendon graft. Nonresorbable suture tape (FiberTape^®, FT) is possibly becoming an option to tendon grafts for MPFL-R. Patella-side fixation of FT can be performed with suture anchors or via soft-tissue fixation. The aim of this study was to investigate patellar tracking considering soft-tissue-based and anchor-based patella-side fixation techniques.

METHODS

In eight fresh-frozen human knee joint specimens (m/f 4/4; age 75 ± 10 years), the MPFL was identified, and a rupture was placed near the femoral insertion site. In the study group (SG; 4 knees), soft-tissue fixation of the FT was performed at the medial patellar retinaculum; in the control group (CG; 4 knees), FT was fixed at the patella via suture anchors. For native MPFL (nMPFL), ruptured ("injured") MPFL (iMPFL) and reconstructed MPFL (FT-MPFL-SG, respectively, FT-MPFL-CG) cone beam CT scans were performed in 15°, 30°, and 45° of knee joint flexion. Patellar tracking was assessed using the radiological parameters patellar tilt (PT), congruence angle (CA) and posterior patellar edge-trochlear groove ratio (PTR).

RESULTS

All recorded radiological parameters increased, respectively, decreased in the CG and SG from the nMPFL to the iMPFL state. After MPFL-R, all parameters normalized when compared to the intact state (nMPFL), regardless of patella-side fixation technique. All investigated parameters of patellotrochlear alignment were positively, respectively, negatively significantly (p < 0.05) correlated throughout all evaluated conditions (nMPFL, iMPFL, FT-MPFL-SG, FT-MPFL-CG).

CONCLUSION

MPFL-R with a nonresorbable suture tape can normalize patellar maltracking in fresh-frozen human knee joint specimens in earlier degrees of knee joint flexion independent of patella-side fixation technique. The investigated parameters of patellotrochlear alignment correlate with each other.

Accuracy of femoral tunnel positioning in medial patellofemoral ligament reconstruction: anatomic insertion leads to better clinical outcome

PURPOSE

The medial patello-femoral ligament (MPFL) is considered the primary restraint against patellar dislocation and its reconstruction is indicated in recurrent patellar instability. An anatomical positioning of MPFL femoral insertion is recommended to achieve satisfactory clinical outcomes and prevent osteoarthritis (OA) due to an altered kinematics. The purpose of the study was first to assess the relationship between correct femoral tunnel position and better clinical outcomes and lower patellofemoral osteoarthritis rate. Second, correlation of outcomes with factors potentially affecting the results, such as the type of graft, patellar height and trochlear dysplasia.

METHODS

Fifty-three patients (58 knees) who underwent MPFL reconstruction between 2009 and 2018 by a senior knee surgeon were retrospectively evaluated. Knee radiographs were performed before surgery, 12 months later and at last follow-up to assess trochlear dysplasia, patellar height and patellofemoral OA. The tibial tuberosity-trochlear groove (TT-TG) value was measured on a CT scan. The accuracy of graft positioning was evaluated on sagittal radiographs according to Schöttle et al. Subjective outcomes were collected before surgery, at 12 months and at last follow-up using several validated scores.

RESULTS

Forty-six patients (51 knees) with a mean age of 24.1 ± 7.4 years were included in the study. Mean follow-up was 8.9 ± 2.1 years. A significant improvement in all clinical scores was observed at 12 months and final follow-up. Anatomic Insertion (AI) of reconstructed MPFL was considered optimal in 33 (64.7%) and sub-optimal in 18 (35.3%) patients. Sub-optimal AI resulted in lower Kujala, IKCD and higher VAS score (p < 0.01); moreover, for every 1 mm distance in any direction from the ideal insertion, a decrease of 0.8 [95% CI (-1.4; -0.2)] in Kujala score and 0.8 [95% CI (-1.3; -0.3)] in IKDC was observed. At final follow-up, 8 patients presented patellofemoral OA Iwano grade 3 (15.7%): although that incidence did not correlate to graft positioning, the use the artificial ligament in all these cases appeared to be significant.

CONCLUSION

The present study confirms the importance of an optimal anatomic femoral insertion in MPFL reconstruction, reporting a significant positive correlation between graft positioning and clinical outcome. No significant correlations were found between anatomic insertion and patello-femoral OA development.

LEVEL OF EVIDENCE

IV.

Patellofemoral articular cartilage damage is associated with poorer patient-reported outcomes following isolated medial patellofemoral ligament reconstruction

PURPOSE

The purpose of this study was to investigate the impact of articular cartilage damage on outcomes following medial patellofemoral ligament (MPFL) reconstruction.

METHODS

Record review identified 160 patients who underwent isolated MPFL reconstruction at a single institution between 2008 and 2016. Patient demographics, patellofemoral articular cartilage status at surgery, and patient anatomical measures from imaging were obtained via chart review. Patients were contacted and outcomes assessed through collection of Norwich Patellar Instability (NPI) score, Knee injury and Osteoarthritis Outcome Score (KOOS), and Marx activity score as well as an assessment for recurrent patellar dislocation. Outcomes of patients with grade 0-II patellofemoral cartilage damage were compared to those of patients with grade III-IV cartilage damage.

RESULTS

One hundred twenty-two patients (76%) with a minimum of one year follow-up were contacted at a mean of 4.8 years post-operatively. A total of 63 patients (52%) had grade III or IV patellofemoral chondral damage at the time of surgery. The majority of the defects was on the medial patella (46 patients-72%) and the mean patellar defect size was 2.8 cm². Among 93 patients who completed patient-reported outcome scores, the 52 with grade III or IV chondral damage reported a significantly poorer KOOS Quality of Life than the 44 patients with grade 0 to II chondral damage (p = 0.041), controlling for patient age, sex, BMI, and anatomical factors.

CONCLUSION

Patients with grade III or IV articular cartilage damage of the patellofemoral joint at the time of MPFL reconstruction demonstrated poorer KOOS knee-related quality of life than patients without grade III or IV articular cartilage damage at a mean of 4.8 years following isolated MPFL reconstruction.

LEVEL OF EVIDENCE

Level II.

Patellar Instability

➢

Certain anatomic factors, such as patella alta, increased tibial tubercle-trochlear groove distance, rotational deformity, and trochlear dysplasia, are associated with an increased risk of recurrent patellar instability.

➢

The presence of a preoperative J-sign is predictive of recurrent instability after operative management.

➢

Isolated medial patellofemoral ligament reconstruction may be considered on an individualized basis, considering whether the patient has anatomic abnormalities such as valgus malalignment, trochlear dysplasia, or patella alta in addition to the patient activity level.

➢

More complex operative management (bony or cartilaginous procedures) should be considered in patients with recurrent instability, malalignment, and certain anatomic factors.

Double-Tunnel Technique Was Similar to Single-Tunnel Technique in Clinical, Imaging and Functional Outcomes for Medial Patellofemoral Ligament Reconstruction: A Randomized Clinical Trial

PURPOSE

This study aimed to compare the clinical, functional, and imaging outcomes of single-tunnel (ST) and double-tunnel (DT) techniques for medial patellofemoral ligament (MPFL) reconstruction.

METHODS

Ninety-four patients with recurrent patellar instability were randomly divided into 2 groups, receiving either ST or DT MPFL reconstruction. Lateral reticulum release (LRR) and tibial tuberosity (TT) transfer were performed as combined procedures when necessary. Preoperative and postoperative clinical characteristics (symptoms and episodes of redislocation), functional outcomes (Kujala, Lysholm, Tegner, IKDC, and KOOS score), and radiological measurements (congruence angle, patellar tilt angle, lateral patellar angle, and lateral patellar translation) were analyzed.

RESULTS

The analysis included data from 90 patients with 48 patients in the ST group and 42 patients in the DT group. Patients were followed up for a mean period of 37.8 (range: 27-50) months in the ST group and 38.6 (range: 25-53) months in the DT group. Forty-three patients in the ST group and 40 patients in the DT group received combined TT transfer, and all patients underwent LRR. At the latest follow-up, 1 patient in ST group experienced redislocation, while no patient in the DT group sustained clinical failure (P = .347). Imaging measurements decreased significantly to the normal range postoperatively. No significant difference was noted between the postoperative radiological results of the 2 groups. All clinical scores significantly improved postoperatively, and no significant difference was observed between the 2 groups except for the higher Lysholm score (P = .031), KOOS symptoms score (P = .021) and KOOS knee-related quality of life score (P = .043) in the DT group.

CONCLUSION

Both techniques could equally mitigate the patellar lateral translation or redislocation. Our results demonstrate several significant differences in functional outcomes that favored DT MPFL reconstruction but no difference in clinical failure rates and radiological results between ST and DT MPFL reconstruction.

LEVEL OF EVIDENCE

Level I, randomized clinical trial.

Age, body mass index, female gender, and patellofemoral cartilage degeneration predict worse patient outcome after patellofemoral instability surgery

PURPOSE

To evaluate predicting factors for patient-reported outcomes and revision interventions following surgical treatment of patients with patellofemoral instability.

METHODS

From a prospective database at the university Orthopedic Department, 138 knees from 116 patients who underwent patellofemoral instability surgery (2012-2019) were enrolled in a retrospective analysis: 34 cases of isolated MPFLrec; 92 cases of MPFLrec plus tibial tuberosity transfer; and 12 cases of MPFLrec plus trochleoplasty. Patient-reported outcome measures were recorded for knee-specific function (KOOS), general quality of life (EQ-5D), and activity level (Tegner scale). Post-operative revision interventions were also actively recorded. As potential predicting factors, patient demographic (gender, age, BMI) and radiographic (pre-operative: patellar height and tilt, tibial tuberosity-trochlear groove distance, trochlear dysplasia, knee osteoarthritis; post-operative: MPFL insertion point; intra-operative: isolated vs. combined procedures, chondropenia severity score) parameters were analyzed using multivariate linear regression models.

RESULTS

With median follow-up of 4.4 (1.0-8.9) years, all patient-reported outcome measures had significantly improved from pre-operative levels: KOOS cumulative, from 71 (15) to 78 (16); EQ-5D, from 0.68 (0.20) to 0.78 (0.21); and Tegner activity scale, from 3 (0-10) to 4 (0-10). No patellofemoral instability revision procedures were performed. One-fifth (27/138) of the operated knees required second surgical interventions, predominately due to hardware or arthrofibrosis. Patients who required post-operative knee manipulation under anesthesia or arthroscopic debridement showed lower post-operative improvement for KOOS cumulative and EQ-5D. Age, BMI, patellofemoral knee osteoarthritis, and shorter follow-up time revealed significant negative correlations to some of the post-operative KOOS subscales. Age was negatively correlated to post-operative EQ-5D, while post-operative Tegner activity scale was negatively correlated to female gender and patellofemoral chondropenia severity score. Femoral MPFL insertion point revealed no association with any outcome measures.

CONCLUSION

Patellofemoral instability surgery for isolated or combined MPFLrec is safe and substantially improves knee function and patient quality of life and activity levels. Serious adverse events are rare, with no recurrent patellofemoral instability. Patients who required post-operative knee manipulation or arthroscopic debridement showed less improvement in subjective measures of treatment outcomes. Older age, higher BMI, worse pre-operative patellofemoral cartilage status, and female gender had negative effects on outcome.

LEVEL OF EVIDENCE

III.

The Schöttle Point Is Consistently Located Distal to the Medial Femoral Physis in Pediatric Patients: A Digitally Reconstructed Radiographic Study

BACKGROUND

Significant controversy surrounds ideal tunnel position for medial patellofemoral ligament (MPFL) reconstruction (MPFLR) in the pediatric setting. The start point for femoral tunnel positioning (the Schöttle point) relative to the distal medial femoral physis is not well defined. Previous studies provide conflicting data regarding position of the MPFL origin and the Schöttle point relative to the distal femoral physis.

HYPOTHESIS

The Schöttle point would be consistently distal to the distal medial femoral physis.

STUDY DESIGN

Descriptive laboratory study.

METHODS

The institutional picture archiving and communication system was queried for computed tomography (CT) imaging studies of pediatric knees. Data were imported to an open-source image computing platform. True lateral digitally reconstructed radiographs and 3-dimensional (3D) renderings were generated, and the Schöttle point was registered in 3D space. Then, 3D distance measurements were obtained from the Schöttle point to the distal medial femoral physis.

RESULTS

A total of 49 pediatric knee CT scans were included. Mean age was 13.0 ± 2.3 years. Mean minimum distance from the medial physis to the Schöttle point was 9.9 ± 3.0 mm (range, 3.4-16.1 mm). In 49 of 49 cases (100%), the Schöttle point was distal to the physis. Using a 6-mm reaming diameter would result in 3 of 49 (6%) femurs having violation of the distal medial femoral physis. Moving the start point 3 mm distally would result in 0 of 49 (0%) sustaining physeal injury.

CONCLUSION/CLINICAL RELEVANCE

The Schöttle point is consistently distal to the distal medial femoral physis. The mean minimum distance from the Schöttle point to the physis on the medial cortex is 9.9 mm. The Schöttle point provides a safe and reliable radiographic landmark for pediatric MPFLR, although reaming diameter should be considered.

Landmarks Used in Medial Patellofemoral Ligament Reconstruction Have Variable Topography

Purpose

To describe the morphology of the adductor tubercle (AT), medial epicondyle (ME), and gastrocnemius tubercle (GT); to quantify their relationships to the medial patellofemoral ligament (MPFL) footprint location; and to classify the reliability of each landmark based on measurement variability.

Methods

Eight cadaveric specimens were dissected to expose the following landmarks on the femur: MPFL footprint, AT, ME, and GT. Using the MicroScribe 3D digitizer, each landmark was projected into a 3-dimensional coordinate system and reconstructed into a complex, closed polygon. For each specimen tubercle, the base surface area, volume, height, base:height ratio, sulcus point, and distance from the MPFL footprint center were calculated. Levene's test was performed to evaluate differences in variance of the morphologic parameters between the three osseous structures.

Results

The ME had significantly greater variance in volume than the GT (P = .032), and the AT (17.5 ± 3.9) and GT (19.5 ± 3.6) were significantly less variable in base:height ratio than the ME (95.3 ± 19.2; P < .001). The GT was the closest to the MPFL footprint center (7.1 ± 3.1 mm) compared with the AT (13.4 ± 3.6 mm, P = .002) and ME (13.2 ± 2.7 mm, P = .003). However, the tubercles were equally variable in terms of distance to the MPFL footprint center (P = .86). Lastly, the sulcus point was estimated to be on average 1.9 ± 2.9 mm distal and 2.0 ± 2.0 mm posterior to the MPFL center point.

Conclusions

The 3 major osseous landmarks of the medial femur have significantly different variances in volume and base:height ratio. Specifically, the variability and elongated morphology of the ME differentiated this landmark from the AT and GT, which demonstrated the most consistent morphology.

Clinical Relevance

The results of this study may be useful to accurately locate landmarks for femoral tunnel placement and determine the isometric MPFL point during reconstruction.

Isolated medial patellofemoral ligament reconstruction results in similar postoperative outcomes as medial patellofemoral ligament reconstruction and tibial-tubercle osteotomy: a systematic review and meta-analysis

PURPOSE

To determine the effect of isolated medial patellofemoral ligament reconstruction (MPFLR) versus concomitant MPFLR and tibial-tubercle osteotomy (TTO) on patient-reported functional outcomes, rate of patellar redislocation, and rate of return to sport in skeletally mature patients with recurrent patellar instability and lateralization as defined by elevated tibial-tubercle trochlear groove (TT-TG) distance.

METHODS

Three databases MEDLINE, PubMed and EMBASE were searched from inception to July 10th, 2022 for literature outlining the management of patients with TT-TG indices greater than 15 mm with either isolated MPFLR or concomitant MPFLR and TTO procedures. The authors adhered to the PRISMA and R-AMSTAR guidelines as well as the Cochrane Handbook for Systematic Reviews of Interventions. Data on functional outcomes via the Kujala anterior knee pain score, redislocation rates, return to sport rates, and complications were recorded. The MINORS score was used for all studies to perform a quality assessment of included studies.

RESULTS

A total of 31 studies comprising 1405 patients (1452 knees) were included in this review. The mean Kujala score in 13 studies comprising 848 total patients in the isolated MPFLR group was 85.0 (range 80.9-97.5) compared to a score of 83.7 (range 77.2-94.0) in 14 studies comprising 459 patients in the concomitant group. The mean pooled redislocation rate in 19 studies examining isolated MPFLR procedures comprising 948 patients was 3.1% (95% CI 2.1-4.4%, I² = 7%) as opposed to 3.2% (95% CI 1.9-5.0%, I² = 0%) in 15 studies comprising 486 patients in the concomitant group. The mean pooled return to sport rate in seven studies with 472 total patients in the isolated MPFLR group was 82% (95% CI 78-86%, I² = 16%) compared to a score of 92% (95% CI 78-99%, I² = 58%) in four studies comprising 54 patients in the concomitant group. There were similar complication rates between both treatment groups, including range of motion deficits, fractures, infections, and graft failures.

CONCLUSION

Isolated MPFLR leads to similar anterior knee pain, similar redislocation rates and lower return to sport rates than concomitant MPFLR and TTO procedures in patients with TT-TG distances greater than 15 mm. Information from this review can aid surgeons in their decision to choose MPFLR versus concomitant procedures for this patient population, and can also guide future studies on this topic.

LEVEL OF EVIDENCE

Level IV.

Magnetic resonance imaging overestimates patellar height compared with radiographs

PURPOSE

To evaluate the inter-observer and inter-method reliability for patellar height measurements between conventional radiographs (CR) and magnetic resonance imaging (MRI) using one or two slices.

METHODS

This was a reliability study, with 60 patients divided in two groups: 30 patients with patellar instability (patella group) and 30 patients with anterior cruciate ligament or meniscus injury (control group). CR and MRI were evaluated by two independent observers. Insall-Salvati index (IS) and Caton-Deschamps index (CD) were measured using three different methods: CR, one-slice MRI or two-slice MRI. Intra-class correlation coefficients (ICC) were calculated for inter-observer reliability and inter-method reliability. Bland-Altman agreement was also calculated.

RESULTS

The inter-observer reliability was very good for the IS with ICCs of 0.93, 0.84 and 0.82, for the CR, one-slice MRI and two-slice MRI, respectively. Similarly, for the CD the ICCs were good, 0.76, 0.80 and 0.75 for the CR, one-slice MRI and two-slice MRI, respectively. No differences were found between the patella and the control group. The inter-method analysis results were: ICCs for IS (0.83, 0.86, 0.93) and CD (0.72, 0.82, 0.83), for the comparisons of CR/one-slice MR, CR/two-slice MRI and one-slice MRI/two-slice MRI, respectively. The Bland-Altman mean differences showed an 8% and a 7% increase on IS values with one-slice MRI and two-slice MRI compared to CR results, while the increase was of 9% and 1% in CD for the respective comparisons with CR.

CONCLUSION

MRI can overestimate patellar height compared to CR, as much as an 8% increase in Insall-Salvati values when using one- or two-slice MRI measurements, and up to a 9% increase in Caton-Deschamps value when using the one-slice MRI method. It is recommended to use the CR as the preferred method when measuring patellar height.

LEVEL OF EVIDENCE

III.

Derotational distal femoral osteotomy for patients with recurrent patellar instability and increased femoral antetorsion improves knee function and adequately treats both torsional and valgus malalignment

PURPOSE

The aim of the study was to evaluate the functional and radiological outcome following derotational distal femoral osteotomy (D-DFO) in patients with high-grade patellofemoral instability (PFI) and an associated increased femoral antetorsion (FA). It was hypothesized that D-DFO would lead to a good functional and radiological outcome, and that both torsional and coronal malalignment could be normalized.

METHODS

Patients that underwent D-DFO between 06/2011 and 12/2018 for high-grade PFI with an increased FA (> 20°) were included. Patient-reported outcome measures (Visual Analog Scale [VAS] for pain, Kujala score, Lysholm score, International Knee Documentation Committee subjective knee form [IKDC], and Tegner Activity Scale [TAS]) were evaluated pre- and minimum 24 months postoperatively. Magnetic resonance imaging of the lower extremity and weight-bearing whole-leg anteroposterior radiographs were conducted pre- and postoperatively. The change in FA, coronal limb alignment, and PROMs were tested for statistical significance.

RESULTS

In total, 27 patients (30 knees) were included. The D-DFO aimed to only correct FA (Group 1) or to additionally perform a varization (Group 2) in 14 cases each. In the remaining two cases, double-level osteotomies were performed to correct additional tibial deformities. In 25 cases (83.3%), concomitant procedures also addressing patellofemoral instability were performed. At follow-up (38.0 months [25-75% interquartile range 31.8-52.5 months]), a significant reduction in pain (VAS for pain: 2.0 [1.0-5.0] vs. 0 [0-1.0], p < 0.05), significant improvement in knee function (Kujala Score: 55.6 ± SD 13.6 vs. 80.3 ± 16.7, p < 0.05; Lysholm Score: 58.6 ± 17.4 vs. 79.5 ± 16.6, p < 0.05; IKDC: 54.6 ± 18.7 vs. 74.1 ± 15.0, p < 0.05), and an increase in sporting activity (TAS: 3.0 [3.0-4.0] vs. 4.0 [3.0-5.0], p = n.s.) were reported. Femoral antetorsion was significantly reduced (28.2 ± 6.4° vs. 13.6 ± 5.2°, p < 0.05). A significant varization was observed in Group 2 (2.4 ± 1.2° valgus vs. 0.3 ± 2.4° valgus; p < 0.05). In one case, patellar redislocation occurred 70 months postoperatively.

CONCLUSION

In patients with PFI and an associated increased FA, D-DFO achieved a significant reduction in pain, an improvement of subjective knee function, as well as an adequate correction of torsional and coronal alignment.

LEVEL OF EVIDENCE

Retrospective case series, Level IV.