Isolated Medial Patellofemoral Ligament Reconstruction Can Be an Effective Procedure in Patellofemoral Instability with Risk Factors

Isolated Medial Patellofemoral Ligament Reconstruction Under Increased Femoral Anteversion Is Associated With Increased Contact Pressure of Medial Patellofemoral Facet at Deep Flexion Angle: A Cadaveric Study

PURPOSE

To analyze (1) whether isolated medial patellofemoral ligament (MPFL) reconstruction in increased femoral anteversion could replicate the patellofemoral (PF) pressure pattern of a hypothetical normal population and (2) the change of PF pressure according to MPFL state under the same anteversion setting.

METHODS

Ten fresh-frozen cadaveric knees were used. Experiments were performed from knee flexion 0° to 90° with 3 MPFL state (intact, released, and reconstructed) and 3 anteversion (initial state, 10° and 20° more increased). Medial and lateral PF joint contact pressures were measured at each point.

RESULTS

At 0° flexion, lateral PF pressure was increased to 62.1 ± 7.8 psi in 10° and 67.3 ± 13.5 psi in 20° more increased anteversion, compared with 43.2 ± 8.6 psi of hypothetical normal population (P .027 and .004, respectively). At 30° flexion, medial PF pressure was decreased to 31.3 ± 11.9 psi in 10° and 27.3 ± 17.5 psi in 20° more increased anteversion, compared with 44.1 ± 10.3 psi of hypothetical normal population (P .009 and .027, respectively). Within the same femoral anteversion, when anteversion was increased 10° and 20° more than the initial state, medial facet pressure after MPFL reconstruction at 90° flexion was increased from 28.7 ± 11.4 psi to 40.0 ± 9.9 psi and 16.7 ± 10.8 psi to 33.9 ± 15.0 psi compared with the intact MPFL (P .047 and <.001, respectively).

CONCLUSIONS

Biomechanically, isolated MPFL reconstruction under increased femoral anteversion was unable to replicate the state of a hypothetical normal population. Even when comparing within the same femoral anteversion, isolated MPFL reconstruction at increased femoral anteversion caused medial PF overpressure at 90° flexion angle.

CLINICAL RELEVANCE

When performing MPFL reconstruction for recurrent patellar dislocation, femoral anteversion should be assessed. Increased femoral anteversion can cause overpressure on the medial facet after isolated MPFL reconstruction.

Double-Level Knee Derotational Osteotomy Yields Better Postoperative Outcomes Than Tibial Tubercle Transfer Combined With Medial Patellofemoral Ligament Reconstruction in Patients With Recurrent Patellar Instability and Severe Malrotation

PURPOSE

To assess the postoperative outcomes of double-level knee derotational osteotomy (KDRO) combined with medial patellofemoral ligament reconstruction (MPFLR) and to compare it with tibial tuber transfer (TTT) and MPFLR without derotational osteotomy in patients with recurrent patellar instability and a marked torsional deformity.

METHODS

From March 2020 to December 2021, patients with torsion deformity (combined femoral torsion [FT] and tibial torsion [TTn] ≥30°) were retrospectively included. The minimum follow-up time was 18 months. Patients who received KDRO and MPFLR were categorized as the KDRO group and patients who received a combined TTT and MPFLR were categorized as the control group. Preoperative and postoperative clinical symptoms, patient-reported outcomes (Kujala, visual analog scale, Lysholm, International Knee Documentation Committee, Tegner, and Knee Injury and Osteoarthritis Outcome scores), and imaging parameters (FT, TTn, patellar height, femoral trochlear dysplasia, congruence angle, patellar tilt angle, lateral patellar angle, lateral patellar translation, and tibial tubercle-trochlear groove distance) were analyzed.

RESULTS

In all, 36 patients were included with 18 in KDRO group and 18 in control group. The mean follow-up time was 30 (range 21-39) months. At the latest follow-up, no patient experienced redislocation in either group. Except for the FT and TTn in the control group, postoperative imaging parameters were significantly reduced to the normal range. KDRO group had a lower patellar tilt angle (P = .043, effect size 0.64). All clinical scores in both groups significantly improved postoperatively. The KDRO group had better functional scores than control group except the KOOS daily living activities subscore and the KOOS sports and recreation subscore. More patients in the KDRO group met the minimal clinically important difference for most patient-reported outcomes than the control group. Eight patients (44%) in the control group complained of postoperative anterior knee pain, compared with 1 patient (6%) in the KDRO group (P = .018).

CONCLUSIONS

KDRO combined with MPFLR was associated with better postoperative outcomes than TTT combined with MPFLR in patients with recurrent patellar instability and a torsion deformity.

LEVEL OF EVIDENCE

Level III, retrospective cohort study.

Impact of the Number of Patellar Dislocations on Outcomes of Isolated Medial Patellofemoral Ligament Reconstruction

Background

Patellar dislocation is a common knee injury and up to 35% of those who dislocate the patella can develop recurrent patellar instability. In the setting of recurrent instability, medial patellofemoral ligament (MPFL) reconstruction is often performed to restore knee stability. There has been recent interest in patient and surgical factors that influence outcomes of MPFL reconstruction. Much of the previous work has focused on influences of anatomic measures; however, patients and injury characteristics may also impact surgical outcomes.

Hypothesis

Patients who experience >2 patellar dislocations before MPFL reconstruction would demonstrate poorer patient-reported outcomes (PROs) compared with those with ≤2 previous dislocations.

Study design

Cohort study; Level of evidence, 3.

Methods

Records were reviewed to identify patients who underwent MPFL reconstruction at a single institution between 2008 and 2016. Patients who underwent concomitant tibial tubercle osteotomy or fixation of an osteochondral fracture were excluded. Patient demographics (age, sex, body mass index [BMI]), number of previous patellar dislocations, and patient anatomic measures (Caton-Deschamps index (CDI), tibial tubercle-trochlear groove (TT-TG) distance, and trochlear sulcus angle) were collected. PROs were assessed with Norwich Patellar Instability score, Knee injury and Osteoarthritis Outcome Score (KOOS), and Marx activity score. Outcomes of patients with >2 patellar dislocations were compared with those with ≤2 dislocations using multiple linear regression analysis.

Results

Medical record review revealed 160 patients who underwent isolated MPFL reconstruction (71 with ≥2 dislocations and 89 with >2 dislocations); 95 patients (59%) completed PROs at a median follow-up of 4.6 years postoperation (range, 1.0-12.6 years). Patients with ≥2 dislocations were younger (≥2 dislocations: 20.7 ± 7.3 years, >2 dislocations: 28.5 ± 10.0 years; P < .001), although there were no other differences in demographics or radiographic anatomic measures between groups. Adjusting for age, sex, BMI, CDI, TT-TG distance, and trochlear sulcus angle, patients with >2 dislocations had 13.7 points lower KOOS-Pain (P = .003), 8.3 points lower KOOS-Activities of Daily Living (P = .025), 18.2 points lower KOOS-Sports and Recreation (P = .009), and 19.8 points lower KOOS-Knee-Related Quality of Life (P = .008) subscale scores than patients with ≤2 dislocations. No significant differences in KOOS symptoms subscale, Norwich Patellar Instability, or Marx score were noted between groups.

Conclusion

Patients with >2 patellar dislocations before MPFL reconstruction exhibited poorer PROs at a median of 4.8 years postoperation compared with those who had ≤2 dislocations before surgery, when adjusting for age, sex, BMI, CDI, TT-TG distance, and trochlear sulcus angle.

Results of medial patellofemoral ligament reconstruction with and without tibial tubercle osteotomy in patellar instability: a systematic review and single-arm meta-analysis

PURPOSE

To confirm which method provides lower rate of recurrent instability and superior clinical outcomes.

METHOD

We searched PubMed, Embase and Web of Science for the trials involving one intervention or both for patellar instability: medial patellofemoral ligament reconstruction (MPFLR) with and without tibial tubercle osteotomy (TTO). The postoperative Kujala score, Lysholm score, Tegner scores and the rate of recurrent instability (dislocation or subluxation) were analyzed as the primary clinical outcome parameters in a random or fixed effects meta-analysis.

RESULTS

In total, 43 articles met inclusion criteria after full-text review. A total of 2046 patients were analyzed. The overall mean age was 20.3 years (range, 9.5-60.0 years), with a mean follow-up time of 3.2 years (range, 1-8 years). The mean Kujala scores in MPFLR and MPFLR + TTO were 89.04 and 84.44, respectively. There was significant difference in Kujala scores between MPFLR and MPFLR + TTO (MD = 4.60, 95%CI: 1.07-8.13; P = 0.01). The mean Lysholm scores in MPFLR and MPFLR + TTO were 90.59 and 88.14, respectively. There was no significant difference in Lysholm scores between MPFLR and MPFLR + TTO (MD = 2.45, 95%CI: -3.20-8.10; P = 0.40). The mean Tegner scores in MPFLR and MPFLR + TTO were 5.30 and 4.88, respectively. There was no significant difference in Tegner scores between MPFLR and MPFLR + TTO (MD = 0.42, 95%CI: -0.39-1.23; P = 0.31). At final follow-up, the rates of recurrent instability in MPFLR and MPFLR + TTO were 3% and 4%, respectively. There was no significant difference in the rates between MPFLR and MPFLR + TTO (OR = 0.99, 95%CI: 0.96-1.02; P = 0.4848).

CONCLUSION

MPFLR and MPFLR + TTO are effective and reliable treatments in the setting of patellofemoral instability. MPFLR seems to show a better performance in functional outcomes than MPFLR + TTO. Moreover, their rates of recurrent instability are very low, and no significant difference exists.

[Patellofemoral instability in children and adolescents]

Patellofemoral instability is a common and clinically relevant disorder of multifactorial causes. Several concomitant problems such as genua valga, hyperlaxity, injuries or sports-related overuse may contribute to the development of instability and recurrent patellar dislocations. A thorough diagnosis is of paramount importance to delineate every contributing factor. This includes radiographic modalities and advanced imaging such as magnetic resonance imaging or torsional analyses. The authors recommend non-operative management (including physiotherapy, gait and proprioceptive training, orthoses) and, whenever non-operative measures fail, surgical patellar stabilization using, e.g. MPFL reconstruction.

Promising results following derotational femoral osteotomy in patellofemoral instability with increased femoral anteversion: A systematic review on current indications, outcomes and complication rate

Purpose

Patellofemoral joint instability (PFJI) can surgically be treated with a multitude of approaches, depending on the underlying pathology. In the presence of increased femoral anteversion, some authors have reported good results with a derotational distal femoral osteotomy (DeDFO). The purpose of the study was to investigate the indications, outcomes and complication rate of DeDFO for PFJI.

Methods

A systematic review was performed according to the PRISMA guidelines (Preferred Reporting Items for Systematic Reviews and Meta-analyses) by searching Medline, Embase, Web of Science and Cochrane Library databases through 1 December 2023. Included were levels 1-4 clinical studies of skeletally mature patients undergoing a DeDFO for PFJI irrespective of concomitant procedures. Study characteristics, indications, radiological and clinical outcomes, surgical technique and concomitant procedures, re-dislocation and complication rate were all analysed, as was methodological quality.

Results

A total of 12 studies including 310 patients (325 knees) were included. Three studies were cohort studies, all others were case series. The mean patient age across the studies was 22 years, and the mean follow-up was 29.4 months. Femoral anteversion cut-off was between 20° and 30°. Every study included at least one concurrent soft tissue, bony or combined procedure. Across all studies, one case of re-dislocation was reported (0.3%) and four implant or osteotomy-related complications (1.2%) were reported. All studies reported a statistically significant increase in clinical scores.

Conclusion

This systematic review of DeDFO for patellofemoral instability in the presence of increased femoral anteversion demonstrates promising clinical results and an extremely low dislocation and complication rate. The heterogeneity of the cut-off in anteversion and concomitant procedures, especially tibial tubercle osteotomy with seemingly identical results, indicates the need for high-quality evidence for treating patellofemoral instability. Based upon this systematic review, we strongly recommend that DeDFO be added to the 'menu à la carte' of PFJI.

Level of Evidence

Level III Systematic Review.

A Combined Surgical Approach for Recurrent Patellar Dislocation in Adolescents With Patella Alta and Increased Tibial Tuberosity-Trochlear Groove Distance: Improved Clinical Outcomes but Decreased Posterior Tibial Slopes in Skeletally Immature Patients at Minimum 4-Year Follow-Up

PURPOSE

(1) To report the clinical and radiological outcomes of a surgical technique combining anatomic medial patellofemoral ligament reconstruction and tibia tuberosity transfer in adolescents with patella alta and elevated tibial tuberosity-trochlear groove (TT-TG) distance in the treatment of recurrent patellar dislocation; and (2) to investigate the potential risks of growth arrest or developmental deformities associated with this combined technique.

METHODS

Medical records of patients who underwent the combined surgery from 2015 to 2019 were reviewed. This study included adolescents aged between 14 and 18 years with a Caton-Deschamps index (CDI) > 1.30 and TT-TG distance >20 mm, with a minimum follow-up of 4 years. Radiological examinations including lateral views and full-length posteroanterior standing radiographs were investigated to assess patella height by CDI, posterior tibial slope (PTS) angle, side-to-side difference in bone length, and lower extremity alignment by hip-knee-ankle angle; computed tomography scans and magnetic resonance imaging profiles were investigated to evaluate TT-TG distance and staging of growth plate closure. Other evaluations included preoperative and postoperative physical examination, Kujala score, and Tegner activity score. The patients were stratified into 3 subgroups according to an magnetic resonance imaging-based staging system of the growth plate closure, and each outcome was analyzed. A cohort-specific minimal clinically important difference estimation was performed using standard error of measurement.

RESULTS

The average age at the time of surgery was 16.1 years (range, 14.1-17.8). The average follow-up was 5.6 years (range, 4.0-7.6). No recurrent dislocation occurred, and no clinically significant deformity or axis deviation was encountered. Postoperative patellar height by CDI was 1.00 ± 0.11 (range, 0.81-1.15). No significant differences were found in the preoperative and postoperative hip-knee-ankle angle or side-to-side difference in femur/tibia length among all subgroups. A significantly decreased PTS angle was found in patients with open growth plates, from 10.2° ± 1.7° before surgery to 8.1° ± 1.0° after surgery (P = .015). The Kujala score and Tegner score both significantly improved, from 65.5 ± 13.9 before surgery to 90.4 ± 7.2 after surgery in the Kujala score (P < .001) and from 4.0 ± 1.1 before surgery to 4.7 ± 1.3 after surgery in the Tegner score (P < .001). Of the whole cohort, 63.1%, 100%, 47.1%, and 94.1% of patients achieved the minimal clinically important difference for PTS angle, CDI, Tegner score, and Kujala score, respectively.

CONCLUSIONS

This combined technique is safe and effective in treating recurrent patellar dislocation in skeletally mature adolescents with concurrent patella alta (CDI > 1.30) and TT-TG distance >20 mm, permitting patients to have improved knee function and low complication rates. Nonetheless, patients with open growth plates demonstrated a decrease in PTS, which might predispose the knee to recurvatum and osteoarthritis in the long term.

LEVEL OF EVIDENCE

Level IV, controlled case series.

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.

Medial patellar ligament reconstruction in combination with derotational distal femoral osteotomy for treating recurrent patellar dislocation in the presence of increased femoral anteversion: a systematic review

BACKGROUND

Medial patellar ligament reconstruction (MPFL-R) in combination with derotational distal femoral osteotomy (DDFO) for treating recurrent patellar dislocation (RPD) in the presence of increased femoral anteversion is one of the most commonly used surgical techniques in the current clinical practice. However, there are limited studies on the clinical outcomes of MPFL-R in combination with DDFO to treat RPD in the presence of increased femoral anteversion.

PURPOSE

To study the role of MPFL-R in combination with DDFO in the treatment of RPD in the presence of increased femoral anteversion.

METHODS

A systematic review was performed according to the PRISMA guidelines by searching the Medline, Embase, Web of Science, and Cochrane Library databases through June 1, 2023. Studies of patients who received MPFL-R in combination with DDFO after presenting with RPD and increased femoral anteversion were included. Methodological quality was assessed using the MINORS (Methodological Index for Nonrandomized Studies) score. Each study's basic characteristics, including characteristic information, radiological parameters, surgical techniques, patient-reported outcomes, and complications, were recorded and analyzed.

RESULTS

A total of 6 studies with 231 patients (236 knees) were included. Sample sizes ranged from 12 to 162 patients, and the majority of the patients were female (range, 67-100%). The mean age and follow-up ranges were 18 to 24 years and 16 to 49 months, respectively. The mean femoral anteversion decreased significantly from 34° preoperatively to 12° postoperatively. In studies reporting preoperative and postoperative outcomes, significant improvements were found in the Lysholm score, Kujala score, International Knee Documentation Committee score, and visual analog scale for pain. Postoperative complications were reported in all studies, with an overall reported complication rate of 4.7%, but no redislocations occurred during the follow-up period.

CONCLUSION

For RPD with increased femoral anteversion, MPFL-R in combination with DDFO leads to a good clinical outcome and a low redislocation rate. However, there was no consensus among researchers on the indications for MPFL-R combined with DDFO in the treatment of RPD.

Clinical outcomes of derotational femoral osteotomy combined with medial patellofemoral ligament reconstruction in patients with patellar dislocation and increased femoral anteversion unaffected by the pattern of distribution of femoral torsion

PURPOSE

The aim of this study was to evaluate the clinical effect of derotational femoral osteotomy combined with medial patellofemoral ligament reconstruction for patellar dislocation and the effect of the distribution of femoral torsion at different segments on postoperative function.

METHODS

Forty-two patients with patellar dislocation who underwent derotational femoral osteotomy from 2017 to 2021 were retrospectively analysed. All patients received computed tomography scans from the hip to the knee to evaluate correction of the femoral anteversion (FA) angle, patellar tilt angle (PTA) and congruence angle (CA) after derotational femoral osteotomy. Subjective scores, such as the Kujala, Lysholm, International Knee Documentation Committee (IKDC), Tegner and visual analog scale (VAS) scores, were used to evaluate knee function before and after the operation. Patients with supracondylar torsion > distal torsion were categorized into the supracondylar torsion group and patients with distal torsion > supracondylar torsion were categorized into the distal torsion group. Subgroup analyses were performed.

RESULTS

No presentation of redislocation occurred in these patients at the minimum 2-year follow-up visit. The mean preoperative FA angle in the supracondylar torsion group was 30.2° ± 4.2°, and the mean postoperative FA angle was 14.5° ± 2.5° (p < 0.001). The mean preoperative FA angle was 26.7° ± 1.4° and the mean postoperative FA angle was 14.1° ± 1.4° in the distal torsion group. In addition, postoperative PTA and CA were significantly corrected in both groups (p < 0.001). The postoperative Kujala, Lysholm, IKDC, Tegner and VAS scores were significantly improved in both groups (p < 0.001). Subgroup analyses showed a higher preoperative FA in the supracondylar torsion group and a higher occurrence of high-grade trochlear dysplasia in the distal torsion group. However, there was no significant difference in their postoperative clinical outcomes.

CONCLUSION

Through a minimum of 2-year follow-up visits of patients with patellar dislocation and increased FA, it was found that derotational femoral osteotomy could significantly reduce FA and improve subjective knee function. The pattern of torsion distribution did not significantly affect the clinical outcomes of derotational femoral osteotomy. These findings readvised orthopaedic surgeons that derotational femoral osteotomy remains the preferred procedure for correcting rotational malalignment, but that they should be more cautious about its indications.

LEVEL OF EVIDENCE

Level IV.

Does Tibial Tuberosity Osteotomy Improve Outcomes When Combined With Medial Patellofemoral Ligament Reconstruction in the Presence of Increased Tibial Tuberosity-Trochlear Groove Distance? A Systematic Review and Meta-analysis

Background

There has been recent debate regarding the optimal surgical management strategy for recurrent patellofemoral instability in the presence of an increased tibial tuberosity-trochlear groove (TT-TG) distance. In particular, performing a combined tibial tuberosity osteotomy (TTO) and medial patellofemoral ligament reconstruction (MPFLR) for patients with a TT-TG >20 mm has been questioned, with the hypothesis that an isolated MPFLR (iMPFLR) would be just as effective.

Purpose

To pool and compare outcomes after MPFLR+TTO versus iMPFLR in patients with a TT-TG >20 mm.

Study Design

Systematic review; Level of evidence, 4.

Methods

PubMed-MEDLINE, Embase, Web of Science, and Cochrane Central were searched, and a systematic review was performed. Included were studies that reported postoperative redislocation rates and/or functional outcome scores for patients with recurrent patellar instability and a TT-TG >20 mm who underwent either MPFLR+TTO or iMPFLR and had minimum 2-year follow-up data. Methodologic quality was assessed using the modified Coleman Methodology Score (mCMS). A proportional meta-analysis comparing redislocation, subjective instability, and total complication rates was performed, and mean postoperative functional outcome scores were pooled using a random-effects model with a restricted maximum likelihood estimator.

Results

In total, 1548 studies were screened, from which 13 were included for analysis. Of the 386 included patients (406 knees), 276 underwent MPFLR+TTO and 110 underwent iMPFLR. The mean mCMS was 61.3 ± 10.5 (range, 48-77). The pooled postoperative redislocation rate was 1.22% (95% CI, 0.22%-7%), with no significant difference between the study groups (P = .9995). The pooled complication rate was 10.17% (95% CI, 6.2%-16.3%) with no difference between groups (P = .9275), although the MPFLR+TTO group had higher heterogeneity in complication rates (I2 = 79.4%) compared with iMPFLR (I2 = 0%). There was no group difference in the pooled postoperative Lysholm scores (P = .5177), but patients who underwent iMPFLR had significantly higher postoperative Kujala scores compared with those who underwent MPFLR+TTO (P = .0283).

Conclusion

Even in the presence of previously indicative anatomic factors (TT-TG >20 mm), TTO combined with MPFLR does not seem to confer additional benefit compared with iMPFLR. This finding could be advantageous in minimizing the burden of additional surgery with its associated risks. The study findings should, however, be interpreted with caution given the heterogeneity of the studies.

Patellar dislocation recurrence after pediatric MPFL reconstruction: Bone tunnels and soft tissues versus suture anchors and interference screw

BACKGROUND

Several Medial Patellofemoral Ligament (MPFL) reconstruction techniques have been developed, and those with soft tissue fixation are often preferred in children because they allow the growth cartilage to be preserved. Nevertheless, the recurrence rate of patellar dislocation varies widely from one series to another, with no clear superiority of one technique in the pediatric setting. The objectives of this study were to compare the results of two tendon graft fixation techniques (tendon-tendon fixation and anchor-screw fixation) by analyzing: 1) the rate of patellar dislocation recurrence, 2) clinical outcomes, 3) tourniquet time and 4) complication rate.

HYPOTHESIS

The two tendon graft fixation techniques used in MPFL reconstruction are equivalent in terms of the patellar dislocation recurrence rate.

PATIENTS AND METHODS

This is a retrospective comparative study including 57 patients with a median age of 14 years (12-15 years) who underwent MPFL reconstruction between 2016 and 2020. The tendon graft was fixed upon itself, after passing through a patellar tunnel (Group A: tendon-tendon fixation; n=29) or by two anchors and an interference screw (Group B: anchor-screw fixation; n=28). The preoperative radiographic data were comparable in the two groups: patellar height [A: 1.3 (interquartile range (IQR): 1.2-1.4) / B: 1.2 (IQR: 1-1.4) (p=0.21)], tibial tuberosity to trochlear groove (TTTG) distance [A: 16 (IQR: 13-19) / B: 13.5 (IQR: 11.5-18.8) (p=0.12)], patellar tilt [A: 25 (IQR: 20-35) / B: 24.5 (IQR: 21-32) (p=0.93)]. For each technique, the rate of patellar dislocation recurrence, clinical and functional results (Kujala score, Marx activity score, Lille patellofemoral score), complications (pain, stiffness, revision) were analyzed. In addition to MPFL repair, 13 patients (2 in Group A, 11 in Group B) underwent additional orthopedic procedures to enhance patellar stability.

RESULTS

no patients were lost to follow-up and the median follow-up was 30 months (IQR: 20-38). The dislocation recurrence rate was higher in Group A, 6.9% (2/29) compared to none in Group B. The clinical results were comparable for the two groups with a Kujala score [A: 94 (IQR: 89-100) / B: 92 (IQR: 87.5-94.5) (p=0.12)]; Marx score [A: 10 (IQR: 7-11) / B: 9.5 (IQR: 7.5-12) (p=0.89)] and Lille patellofemoral score [A: 97 (IQR: 91-100) / B: 94 (IQR: 90-98) (p=0.21)]. The tourniquet time was shorter in Group A than in Group B, 61minutes (IQR: 52-71) versus 85minutes (IQR: 55-115) (p=0.024) excluding additional orthopedic procedures. The complication rate was 17.2% (5/29) in Group A (dislocation n=2, stiffness n=2, ATT (anterior tibial tuberosity) revision with screw removal n=1) and 10.7% (3/28) in B (pain n=1, ATT revision with screw removal n=2) (p=0.35).

CONCLUSION

Clinically, anchor-screw fixation appears to reduce the risk of patellar dislocation recurrence but this could not be statistically tested. On the other hand, the two techniques are comparable in terms of the functional results.

LEVEL OF EVIDENCE

III; retrospective case-control study.

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.

Clinical Insights into the Treatment of Patellofemoral Instability with Medial Patellofemoral Ligament Reconstruction: Pearls and Pitfalls-Lessons Learned from 20 Years

Patellofemoral instability is a prevalent cause of pain and disability in young individuals engaged in athletic activities. Adolescents face a particularly notable risk of patellar dislocation, which can be attributed to rapid skeletal growth, changes in q-angle, ligamentous laxity, higher activity levels, and increased exposure to risk. Specific sports activities carry an elevated risk of patellar dislocation. Younger age and trochlear dysplasia present the highest risk factors for recurrent patellar dislocations. International guidelines recommend conservative therapy following a single patellar dislocation without osteochondral lesions but suggest surgical intervention in recurrent cases. In this study, we have compiled current scientific data on therapy recommendations, focusing on MPFL (medial patellofemoral ligament) reconstruction. We discuss patient selection, surgical indications, graft selection, location and choice of fixation, graft tensioning, and postoperative care.

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.

Stiffness and Instability After MPFL Reconstruction Using a Fluoroscopic Versus Open Technique to Localize the Femoral Attachment Site: A Systematic Review and Meta-analysis

Background

Open and fluoroscopic techniques have been described for localization of the femoral attachment site in medial patellofemoral ligament (MPFL) reconstruction. No study to date has evaluated if one technique is superior to another in terms of complications.

Purpose

To review the literature comparing clinical outcomes of MPFL reconstruction using the fluoroscopic versus open technique to localize the site of femoral graft placement.

Study Design

Systematic review; Level of evidence, 4.

Methods

A systematic literature review was performed via PubMed, Embase, and CINAHL to identify articles published between the inception of these databases and March 1, 2022, in accordance with the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. This search yielded 4183 publications for initial review. Studies with at least a 2-year follow-up and complete reporting of patient-reported outcomes, range of motion, recurrent instability, and/or complications (ie, stiffness, infection, persistent pain) were included. We excluded studies of patients with collagen disorders; revision surgeries; surgeries with concomitant procedures; synthetic MPFL reconstruction; MPFL repairs; combined open and radiographic technique; and case series that included <10 patients. A proportional meta-analysis was performed by calculating the pooled estimate of incidence with 95% CIs using a fixed-effects model with double arcsine transformation (Freeman-Tukey) for each type of surgical technique (fluoroscopic or open).

Results

A total of 29 studies met our inclusion criteria, of which 15 studies (566 patients) used the open technique and 14 studies (620 patients) used fluoroscopy. There were no significant differences between the open and fluoroscopic techniques in the incidence of postoperative apprehension (P = .4826), postoperative subjective instability (P = .1095), postoperative objective instability (P = .5583), reoperations (P = .7981), recurrent dislocation (P = .6690), or arthrofibrosis (P = .8118).

Conclusion

Both open and radiographic localization of the femoral graft position in MPFL reconstruction offer similar outcomes and rates of complications.

Medial patellofemoral ligament reconstruction combined with derotational distal femoral osteotomy yields better outcomes than isolated procedures in patellar dislocation with increased femoral anteversion

PURPOSE

The purpose of this study was to evaluate and compare clinical and radiological outcomes between isolated medial patellofemoral ligament reconstruction (MPFLR) and MPFLR combined with derotational distal femoral osteotomy (DDFO) for patellar dislocation with increased femoral anteversion (FA).

METHODS

Between 2014 and 2019, 36 patients who underwent isolated MPFLR and 31 patients who underwent MPFLR combined with DDFO were retrospectively included. Clinical outcomes included physical examinations, functional outcomes (Kujala, Lysholm, International Knee Documentation Committee (IKDC), and Banff Patella Instability Instrument (BPII) scores), activity level (Tegner activity score and return to sports), complications, and patellar re-dislocation rate. Radiological outcomes included patella tilt angle, patellar congruence angle, and patella-trochlear groove distance.

RESULTS

All clinical outcomes improved significantly in both groups, but the DDFO group had significantly better postoperative scores than the MPFLR group (Kujala: 85.1 ± 7.7 vs. 80.5 ± 8.4, P = 0.023; Lysholm: 86.8 ± 8.2 vs. 81.9 ± 9.1, P = 0.026; IKDC: 86.2 ± 10.0 vs. 81.7 ± 8.1, P = 0.045; and BPII: 68.0 ± 12.5 vs. 62.3 ± 10.0, P = 0.039). Both groups achieved successful return to sports (90.3% vs. 91.7%). No re-dislocation or major complications occurred. Radiological outcomes improved significantly in both groups, but the DDFO group had better outcomes (P < 0.05). The tibial tubercle-trochlear groove distance was only improved after DDFO from 17.0 ± 2.3 mm to 15.1 ± 2.0 mm (P = 0.001).

CONCLUSION

Both isolated MPFLR and MPFLR combined with DDFO yielded satisfactory clinical and radiological outcomes in the treatment of patellar dislocation with increased FA. However, combined DDFO had better outcomes and should be considered a priority.

LEVEL OF EVIDENCE

Level III.

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.

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.

Influence of Patellofemoral Anatomy on Outcomes of Isolated Medial Patellofemoral Ligament Reconstruction for Recurrent Patellar Instability

Background:

Patella alta and elevated tibial tubercle–trochlear groove (TT-TG) distance can predispose patients to lateral patellar dislocations and recurrent instability. Their influence on patient-reported outcomes (PROs) after medial patellofemoral ligament (MPFL) reconstruction is less clear.

Hypothesis:

We hypothesized that neither moderately increased TT-TG distance nor patella alta would negatively affect PROs after isolated MPFL reconstruction in patients with relatively normal patellar tracking (no large J-sign).

Study Design:

Cohort study; Level of evidence, 3.

Methods:

We identified patients who underwent isolated MPFL reconstruction at a single institution between 2008 and 2016. The decision to perform an isolated MPFL reconstruction was at the discretion of the operating surgeon but was not performed in the setting of a large J-sign. Patient characteristics and surgical details were collected, and patients completed the Norwich Patellar Instability Score, Knee injury and Osteoarthritis Outcome Score, and Marx activity score. Patellar height (Caton-Deschamps Index [CDI]) was assessed on preoperative lateral radiographs, and TT-TG distance was measured on preoperative axial magnetic resonance imaging (MRI) scans. Patients were grouped based on CDI and TT-TG distance, and outcomes were compared. Linear regression modeling was performed to determine whether patella alta or elevated TT-TG distance was associated with poorer PRO scores.

Results:

Of 165 knees in 152 patients who underwent isolated MPFL reconstruction, 115 patients (125 knees; 76%) with minimum 1-year follow-up were contacted at a mean of 5.2 years after surgery. Recurrent dislocation occurred in 5 of 125 knees (4%). Preoperative radiographs were available in 111 knees (89%), and preoperative MRI scans were available in 89 knees (71%). Mean CDI was 1.13, and 35% had a CDI ≥1.20. Mean TT-TG distance was 17.5 mm, and 26% had a TT-TG distance >20 mm. After adjusting for patient age, sex, body mass index, and graft choice, we observed that neither patella alta nor elevated TT-TG distance were associated with poorer PROs.

Conclusion:

Isolated MPFL reconstruction in the setting of moderately elevated TT-TG distance or patella alta was not associated with worse PROs in this cohort with relatively normal patellar tracking (no large J-sign).

Inconsistencies in Reporting Risk Factors for Medial Patellofemoral Ligament Reconstruction Failure: A Systematic Review

BACKGROUND

Medial patellofemoral ligament (MPFL) reconstruction is a common surgical treatment for patients with recurrent patellar instability. A variety of risk factors, such as age, trochlear dysplasia, patella alta, and increased tibial tubercle-trochlear groove (TT-TG) distance, have been identified and may lead to postoperative failure or poor outcomes.

PURPOSE

While a large number of risk factors have been identified, significant heterogeneity exists in evaluating and reporting these risk factors in the literature. The goal of this study was to perform a systematic review to determine risk factors associated with worse outcomes after MPFL reconstruction and their consistency of being controlled for or analyzed among studies.

STUDY DESIGN

Systematic review; Level of evidence, 4.

METHODS

A systematic review of the literature was performed using the MEDLINE database to identify relevant clinical outcome studies after MPFL reconstruction for recurrent patellar instability. Eligible studies were evaluated for risk factors that were associated with MPFL failure, defined as recurrent instability or lack of improvement on patient-reported outcome (PRO) scores. Each study was then evaluated for inclusion of these risk factors.

RESULTS

Ten studies were included in the final analysis, comprising 1287 knees from 1275 patients who underwent isolated MPFL reconstruction. Of these 10 studies, 8 defined outcomes based on PROs and 3 defined outcomes based on postoperative recurrent instability (1 study included both outcomes). In the PRO failure group, 12 risk factors were found across all studies: trochlear dysplasia, trochlear bump height, elevated TT-TG, patellar tilt, hyperlaxity, age at first dislocation, age at surgery, body mass index, bilateral symptoms, WARPS/STAID score (weak atraumatic, risky anatomy, pain, and subluxation/strong, traumatic, anatomy normal, instability, and dislocation), femoral tunnel malposition, and femoral tunnel widening. In the recurrent instability failure group, 7 risk factors were found across all studies: trochlear dysplasia, bump height, patella alta, higher sulcus angle, higher congruence angle, preoperative J sign, and femoral tunnel malposition. Trochlear dysplasia and femoral tunnel malposition were consistently cited in several studies as risk factors for worse PROs and higher rates of recurrent instability. Patella alta was indicated as a significant risk factor for recurrent instability in 1 of 2 studies analyzing postoperative instability failures and was not associated with worse PROs in any of the studies analyzed. Similarly, elevated TT-TG distance was not a significant risk factor in any of the studies that analyzed recurrent instability as the failure endpoint.

CONCLUSION

While various risk factors are postulated to affect outcomes after MPFL reconstruction, there remains inconsistency within the literature regarding the inclusion of all risk factors in a given analysis. Furthermore, the significance of these risk factors varies among studies in terms of whether they affect postoperative outcomes. We found that more severe trochlear dysplasia (types C and D) and femoral tunnel malposition (>10 mm from Schöttle's point) appear to have the most consistent effect on producing higher rates of recurrent dislocation as well as worse PROs. Despite this, the role of concomitant bony procedures to adjust certain pathoanatomic risk factors in addition to MPFL reconstruction remains unknown. Future high-level studies must be conducted that respect the multifactorial nature of patellar instability and should analyze all risk factors (demographic, anatomic, and radiographic) reported to affect outcomes.

Effect of Isolated Medial Patellofemoral Ligament Reconstruction in Patellofemoral Instability Regardless of Predisposing Factors

The purpose of this study was to evaluate the outcomes of isolated medial patellofemoral ligament (MPFL) reconstruction, regardless of the presence of predisposing factors. A total of 21 knees that underwent isolated MPFL reconstruction from March 2014 to August 2017 were included in this retrospective series. Radiographs of the series of the knee at flexion angles of 20, 40, and 60 degrees were acquired. The patellar position was evaluated using the patellar tilt angle, sulcus angle, congruence angle (CA), and Caton-Deschamps and Blackburne-Peel ratios. To evaluate the clinical outcome, the preoperative and postoperative International Knee Documentation Committee (IKDC) and Lysholm knee scoring scales were analyzed. To evaluate the postoperative outcomes based on the predisposing factors, the results were separately analyzed for each group. Regarding radiologic outcomes, 20-degree CA was significantly reduced from 10.37 ± 5.96° preoperatively to -0.94 ± 4.11° postoperatively (p = 0.001). In addition, regardless of the predisposing factors, delta values of pre- and postoperation of 20-degree CA were not significantly different in both groups. The IKDC score improved from 53.71 (range: 18-74) preoperatively to 94.71 (range: 86-100) at the last follow-up (p = 0.004), and the Lysholm score improved from 54.28 (range: 10-81) preoperatively to 94.14 (range: 86-100) at the last follow-up (p = 0.010). Isolated MPFL reconstruction provides a safe and effective treatment for patellofemoral instability, even in the presence of mild predisposing factors, such as trochlear dysplasia, increased patella height, increased TT-TG distance, or valgus alignment. This is a Level 4, case series study.

Derotational Femoral Osteotomy for Treating Recurrent Patellar Dislocation in the Presence of Increased Femoral Anteversion: A Systematic Review

Background:

Studies on the clinical outcomes of derotational femoral osteotomy to treat recurrent patellar dislocation in the presence of increased femoral anteversion are limited.

Purpose:

To investigate the role of derotational femoral osteotomy in the treatment of recurrent patellar dislocation in the presence of increased femoral anteversion.

Study Design:

Systematic review; Level of evidence, 4.

Methods:

A systematic review was performed according to the PRISMA guidelines (Preferred Reporting Items for Systematic Reviews and Meta-analyses) by searching the Medline, Embase, Web of Science, and Cochrane Library databases through February 10, 2021. Included were studies of skeletally mature patients presenting with recurrent patellar dislocation and exhibiting increased femoral anteversion who subsequently underwent derotational femoral osteotomy. Methodological quality was assessed using the MINORS (Methodological Index for Nonrandomized Studies) score. The basic characteristics of each study were recorded and analyzed: characteristic information, radiological parameters, surgical techniques, patient-reported outcomes, and complications.

Results:

A total of 6 studies with 163 patients (170 knees) were included. Sample sizes ranged from 7 to 66 patients, and the patients were predominantly women (range, 79%-100%). The mean age and follow-up ranges were 18 to 28 years and 16 to 44 months, respectively. The mean femoral anteversion decreased significantly from 34° preoperatively to 12° postoperatively. In studies reporting pre- and postoperative outcomes, significant improvements were found in the Lysholm score (from 24.8 to 44.1), Kujala score (from 15.8 to 41.9), International Knee Documentation Committee score (from 11.0 to 28.0), and visual analog scale for pain (from 2.0 to 3.7). All studies reported postoperative complications, giving an overall reported complication rate of 4.7%, but no redislocations occurred during the follow-up period.

Conclusion:

For recurrent patellar dislocation in the presence of increased femoral anteversion, combination treatment with derotational femoral osteotomy led to favorable clinical outcomes with a low redislocation rate. However, there was no consensus among researchers on the indications for derotational femoral osteotomy in the treatment of recurrent patellar dislocation.

Medial Patellofemoral Ligament Reconstruction Techniques and Outcomes: a Scoping Review

PURPOSE OF REVIEW

The purpose of this scoping literature review was to summarize the current evidence on techniques and outcomes following MPFL reconstruction including sources of evidence, key concepts, and gaps in the literature.

RECENT FINDINGS

A thorough electronic database search included studies published from 2016 to April 26, 2021, identified a total of 144 peer reviewed articles. Of the 144 identified clinical papers, 80 (56%) were of level IV evidence, 49 (34%) were of level III evidence, 11 (8%) were level II evidence, and 4 (3%) were level I evidence. Overall, 10,710 patients (11,466 knees) were included with 6871 (64%) female. The mean age of patients included in these studies was 23.5 years (range=5 to 59). In recent years, there has been a substantial quantity of evidence published on MPFL reconstruction from a variety of different countries and journals and of variable methodological design. Isolated MPFL reconstruction results in a decrease in patellar height postoperatively. Indications for isolated MPFL reconstruction versus concomitant procedures to address bony morphology is still incompletely defined. When failure does occur after MPFL reconstruction, femoral tunnel malposition is the most commonly cited cause. Despite several recent studies focused on optimal MPFL reconstruction techniques, there is currently no consensus on optimal graft type (most common being hamstring autografts, allografts, and recently synthetic grafts) or femoral fixation strategies, with similar results reported with each technique. Future studies should focus on optimal techniques for each patient population as well as specific indications for additional concomitant realignment procedures.

Clinical Outcomes and Prognostic Factors in Patients With Recurrent Patellar Lateral Dislocation Treated With Isolated Medial Patellofemoral Ligament Reconstruction: A Retrospective Single-Center Analysis

Background

Medial patellofemoral ligament reconstruction (MPFLR) is widely used to treat patellofemoral instability. However, it is still unclear when a concomitant bony procedure is needed.

Purpose

To evaluate the therapeutic efficacy of isolated MPFLR for recurrent patellar lateral dislocation and to identify the prognostic factors for clinical outcomes.

Study Design

Case series; Level of evidence, 4.

Methods

A total of 237 patients who had undergone unilateral isolated MPFLR between January 2011 and December 2016 were included. Patellar tracking (J sign) and radiologic information including patellar height, trochlear dysplasia, tibial tubercle-trochlear groove distance, and patellar tilt was collected preoperatively, and the Kujala and International Knee Documentation Committee (IKDC) functional scores were used to assess postoperative recovery. Failure was defined as redislocation or patient-reported and clinically confirmed patellar instability. The influence of radiologic features and the J sign on knee functional scores was explored via subgroup analysis. Potential prognostic factors were explored using univariate and multivariate regression analyses, and risk factors for a positive J sign were evaluated using Spearman coefficient correlation analysis.

Results

The mean ± SD follow-up period was 70.67 ± 18.05 months (range, 36-108 months). From preoperatively to final follow-up, all patients had statistically and clinically significant improvements in the Kujala score (from 51.43 ± 6.87 to 88.52 ± 4.83; P < .001) and IKDC score (from 49.78 ± 6.05 to 81.16 ± 4.20; P < .001). Subgroup analysis indicated no significant difference in functional score improvements based on radiologic features or the J sign. Overall, 20 knees (8.4%) experienced postoperative failure: 11 with redislocation and 9 with patellar instability. A preoperative positive J sign was shown to be an independent prognostic factor for postoperative failure via logistic regression analyses: univariate (odds ratio, 3.340; 95% CI, 1.316-8.480; P = .011) and multivariate (odds ratio, 3.038; 95% CI, 1.179-7.827; P = .021). In addition, the J sign was closely associated with patellar height (r _S, 0.159; P = .014) and trochlear dysplasia (r _S, 0.235; P < .001).

Conclusion

Isolated MPFLR appears to be an effective strategy for recurrent patellar lateral dislocation, with significant functional improvement and a low failure rate. A preoperative positive J sign was identified as a potential prognostic risk factor for postoperative failure.

Medial Patellofemoral Ligament Reconstruction With or Without Derotational Distal Femoral Osteotomy in Treating Recurrent Patellar Dislocation With Increased Femoral Anteversion: A Retrospective Comparative Study

BACKGROUND

Controversy exists regarding the surgical treatment of recurrent patellar dislocation (RPD) with an increased femoral anteversion angle (FAA). Medial patellofemoral ligament reconstruction (MPFL-R) either alone or combined with derotational distal femoral osteotomy (DDFO) results in favorable clinical outcomes.

PURPOSE

To compare the clinical outcomes of MPFL-R versus MPFL-R with DDFO in treating RPD with increased FAA (>30°).

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Between January 2014 and December 2017, 126 patients (135 knees) with RPD and increased FAA (>30°) were surgically treated using MPFL-R with or without DDFO and eligible for this retrospective study. These patients were allocated into 2 groups based on whether an additional DDFO was performed: the DDFO group (MPFL-R + DDFO with or without tibial tubercle transfer; n = 66) and the control group (MPFL-R with or without tibial tubercle transfer; n = 69). Pre- and postoperative patellar stability was measured using stress radiography. Patellar maltracking (J-sign) and patient-reported outcomes (Kujala, International Knee Documentation Committee, Lysholm, and Tegner scores) were evaluated and compared between the 2 groups. Subgroup analysis was performed by stratifying the results in terms of the severity of preoperative patellar maltracking (low-grade vs high-grade J-sign).

RESULTS

A total of 135 knees (126 patients) with a mean follow-up time of 3.7 ± 1.2 years were evaluated in the present study. The rates of postoperative MPFL residual graft laxity and residual J-sign were significantly lower in the DDFO group than in the control group (6% vs 19%, P = .028; 33% vs 54%, P = .018). The DDFO group had significantly higher Kujala (82.3 vs 76.7; P = .001) and Lysholm (83.7 vs 77.7; P = .034) scores than the control group had postoperatively. For patients with a preoperative high-grade J-sign, further subgroup analysis demonstrated that the DDFO group had a significantly lower rate of MPFL residual graft laxity than the control group had (18% vs 57%; P = .029).

CONCLUSION

In this retrospective study, treatment of RPD with increased femoral anteversion using MPFL-R with DDFO yielded more favorable subjective and objective outcomes than did MPFL-R without DDFO, and this circumstance was more remarkable when the patients had a preoperative high-grade J-sign.

High failure rate 10.8 years after vastus medialis transfer and lateral release (Green's quadricepsplasty) for recurrent dislocation of the patella

PURPOSE

In adolescent patients with recurrent patellar dislocation, the Green's quadricepsplasty stabilizes the patella in a combination of a lateral release, a transfer of the medial head of the quadriceps onto the lateral part of the patella and an imbrication of the medial patellar retinaculum and joint capsule. This study aimed to evaluate the long-term performance, considering re-dislocations and functional outcomes. We hypothesized a high failure rate in the long term.

METHODS

In this single surgeon and single center study 26 knees in 23 patients (mean age 14.2 years; 4-22 years, 18 females) with recurrent patellofemoral dislocation underwent a vastus medialis transfer, medial reefing and lateral release as it was described by Green in 1965 with a mean follow-up 10.8 years (6-24 years). Clinical assessment was carried out with an IKDC-score (international knee documentation committee) and a self-assessment for each knee separately. The radiologic evaluation included measurement of the patella height, the grade of trochlear dysplasia and the sulcus angle.

RESULTS

In 12 of 26 cases (46.2%) the patella did not re-dislocate after vastus medialis transfer and lateral release. In 11 of 26 cases (42.3%), the patients described the function of their knees as normal or nearly normal according to IKDC after the surgical treatment without any re-dislocation. In 14 of 26 cases (53.8%), the patella re-dislocated. 7 of these 14 cases underwent a revision operation. Re-dislocations occurred after a mean interval of 21 months after the index procedure. In only 2 of 26 cases (7.7%) the patients returned to sports.

CONCLUSION

Green's procedure to stabilize patellofemoral instabilities results in a high failure rate on the long-term and low subjective assessments. We do not recommend performing vastus medialis transfer, medial imbrication and lateral release as a standalone technique.

LEVEL OF EVIDENCE

IV.

Preoperative Complete Patellofemoral Dislocation in Extension Predicts an Inferior Clinical Outcome After Medial Patellofemoral Ligament Reconstruction in Patients With Recurrent Patellar Dislocation

Background:

Habitual patellar dislocation in extension (HPD-E) is a distinctive subtype of recurrent patellar dislocation (RPD); HPD-E represents the most severe type of patellar maltracking in RPD. It has been reported that the presence of preoperative patellar maltracking is associated with a worse clinical outcome after medial patellofemoral ligament (MPFL) reconstruction (MPFL-R).

Purpose:

To describe the radiological characteristics of HPD-E and to compare clinical outcomes after MPFL-R among patients with and without preoperative HPD-E.

Study Design:

Cohort study; Level of evidence, 3.

Methods:

From January 2012 to December 2015, a total of 230 consecutive patients (246 knees) with RPD were treated with MPFL-R alone or combined with tibial tubercle osteotomy. Among them, 28 patients diagnosed with HPD-E by preoperative 3-dimensional computed tomography (CT; HPD-E group) were matched in a 1:1 fashion to 28 control participants who did not show HPD-E (control group). Routine radiography and CT were performed to evaluate patellar height, trochlear dysplasia, tibial tubercle–trochlear groove distance, and torsional deformities. The mean patellar laxity index and lateral patellar translation assessed with stress radiography were measured preoperatively and postoperatively to quantify MPFL laxity. At minimum 2-year follow-up, patient-reported outcomes (Kujala, Lysholm, and Tegner scores), patellar maltracking, and redislocation rates were compared between the HPD-E and control groups.

Results:

The radiological characteristics of the HPD-E group were as follows: 89% (25/28) of patients had severe trochlear dysplasia (Dejour type B or D), and the mean femoral anteversion angle was 35.5° ± 4.7°. At the final follow-up, the HPD-E group had a significantly lower Kujala score (76.2 vs 84.5, respectively; P = .001), Lysholm score (75.4 vs 86.6, respectively; P < .001), and Tegner score (4.1 vs 5.8, respectively; P = .021) compared with the control group. The postoperative patellar laxity index (43% vs 19%, respectively; P < .001) and redislocation rate (25% vs 0%, respectively; P = .01) were significantly higher in the HPD-E group than in the control group.

Conclusion:

Preoperative 3-dimensional CT is a reliable method of identfying patients with HPD-E. Treatment of HPD-E by MPFL-R alone or combined with tibial tubercle osteotomy resulted in a higher redislocation rate, more severe MPFL residual laxity, and lower patient-reported outcome scores compared with patients without HPD-E who underwent MPFL-R.

Identifying Patients With Patella Alta and/or Severe Trochlear Dysplasia Through the Presence of Patellar Apprehension in Higher Degrees of Flexion

Background:

Recurrent patellar instability is frequently treated surgically with reconstruction of the medial patellofemoral ligament (MPFL). Patients with significant patella alta, trochlear dysplasia, and/or an elevated tibial tubercle–trochlear groove (TT-TG) distance may benefit from a concurrent bony procedure such as tibial tubercle osteotomy or trochleoplasty. The indications to perform such procedures are traditionally based on imaging criteria but remain controversial. Patellar apprehension is common in patients with patellar instability but typically resolves in higher degrees of knee flexion.

Hypothesis:

The persistence of patellar apprehension at greater than 60° of knee flexion is associated with patella alta, an increased TT-TG distance, and trochlear dysplasia.

Study Design:

Cross-sectional study; Level of evidence, 3.

Methods:

A total of 76 patients with recurrent patellar instability were prospectively identified in a sports medicine clinic. Patellar apprehension was evaluated in each patient. Apprehension was defined as the patient reporting that the patella felt unstable to lateral patellar translation. Apprehension was first assessed at full knee extension and repeatedly assessed as the knee was flexed in 10° intervals, as measured using a goniometer. The degree of flexion at which patellar apprehension disappeared was recorded. Plain radiographs and magnetic resonance imaging (MRI) scans were obtained for all patients. Patellar height was assessed with the Caton-Deschamps (CD) index, and trochlear morphology was assessed through measurements of the sulcus angle and depth on MRI and classified using the Dejour classification system. Imaging measurements of patients in whom apprehension resolved by 60° of knee flexion were compared with measurements for those with apprehension that persisted deeper into flexion.

Results:

Apprehension resolved by 60° of flexion in 56 patients and persisted into deeper flexion in 20 patients. The patients with a delayed resolution of apprehension demonstrated a higher CD index; elevated TT-TG distance; increased sulcus angle; decreased sulcus depth; and higher incidence of Dejour type B, C, or D dysplasia (all P < .05). Of the 20 patients with a delayed resolution of apprehension, 18 had either Dejour type B, C, or D dysplasia or a CD index of at least 1.30. A delayed resolution of apprehension was present in 11 of the 16 patients with Dejour type B, C, or D dysplasia.

Conclusion:

Overall, 90% of patients with significant patella alta and the majority of patients with high-grade trochlear dysplasia demonstrated patellar apprehension that persisted beyond 60° of knee flexion. Additionally, 90% of patients with persistent apprehension had significant patella alta and/or trochlear dysplasia. Further work is needed to evaluate the utility of these findings to inform surgical decision-making in this population.