Patient-Reported Outcomes After Revision Surgery for Failed Medial Patellofemoral Ligament Reconstruction: A Matched-Pair Analysis Including Correction of Predisposing Factors

Large variability in minimal clinically important difference, substantial clinical benefit and patient acceptable symptom state values among literature investigating patellar stabilization surgery: A systematic review

PURPOSE

To investigate minimal clinically important difference (MCID), substantial clinical benefit (SCB), patient acceptable symptom state (PASS) values for patient-reported outcome measures (PROMs) after patellar stabilization surgery for patellar instability. Secondary outcomes included to describe methods to calculate clinically significant outcomes (CSOs), and to report on the achievement of these metrics.

METHODS

On 31 July 2024, three databases were searched. Information on whether studies calculated MCID, SCB or PASS values or used previously established values was recorded. Data on study characteristics, CSO values, and the method of MCID quantification (e.g., distribution vs. anchor) were extracted.

RESULTS

A total of 17 articles with 1447 patients (1462 knees) were included. A total of 18 unique outcome measures were reported. Six out of 15 (40%), 2 out of 5 (40%), and zero studies used prior established values for MCID, SCB and PASS, respectively. MCID ranged widely (e.g., International Knee Documentation Committee [IKDC]: 5.6-20.5; Kujala Anterior Knee Pain Scale: 5.38-11.9 and Lysholm: 5.6-11.1). Fourteen out of 15 utilized a distribution-based method to calculate MCID, with only one study using an anchor-based method. SCB values ranged widely as well (e.g.

, IKDC

14.5-23.6; Knee Osteoarthritis and Outcome Score [KOOS] symptoms: 4.2-14.2 and KOOS activities of daily living [ADLs]: 6.5-25.7). Large variability was found among percentages of patients that achieved MCID values (e.g.

, IKDC

28%-98.6%, Kujala: 38%-100%, Lysholm: 44%-98.4% and Tegner: 84%-95%).

CONCLUSION

The significant heterogeneity in reported thresholds for MCID, SCB and PASS across studies highlights critical challenges in interpreting results after patellar stabilization surgery, specifically regarding what constitutes a clinically relevant outcome. MCID was the most commonly reported metric and calculated predominantly with distribution-based methods, with over half of the studies using previously established thresholds. PASS and SCB were widely underreported as well, suggesting a need for studies investigating patellar stabilization to prioritize the calculation of all three metrics, using anchor-based techniques.

LEVEL OF EVIDENCE

Level IV.

Thin Flap Trochleoplasty With Medial Patellofemoral Ligament Reconstruction for Recurrent Patellofemoral Instability With High-Grade Trochlear Dysplasia: A Series of 63 Consecutive Cases

BACKGROUND

Trochlear dysplasia is present in 68% to 85% of patients with recurrent lateral patellofemoral instability (LPI) compared with 3% to 6% of healthy controls. Trochlear dysplasia has been associated with medial patellofemoral ligament (MPFL) graft failure and lower quality-of-life (QOL) outcome scores. The correction of trochlear dysplasia with trochleoplasty is indicated in patients with recurrent LPI and high-grade trochlear dysplasia with a trochlear bump and a significant J-sign.

PURPOSE

To assess the clinical and patient-reported outcomes after patella-stabilizing surgery, including thin flap sulcus deepening trochleoplasty, and to explore the influence of pathoanatomic variables on postoperative QOL scores in patients who have undergone patellar stabilization, including trochleoplasty.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

A total of 63 consecutive knees in 46 patients with recurrent LPI and high-grade trochlear dysplasia who underwent MPFL reconstruction with thin flap trochleoplasty were followed for 2 years postoperatively. Clinical outcomes and Banff Patellofemoral Instability Instrument (BPII) 2.0 scores were collected prospectively. The t test was used to determine changes in QOL. Multiple linear regression was conducted to determine significant pathoanatomic variables that affected outcomes after MPFL reconstruction.

RESULTS

Overall, 63 knees with a mean follow-up of 32.9 ± 17.0 months (range, 12-84 months) were included. All patients had preoperative high-grade trochlear dysplasia (Dejour type B: 46%; Dejour type D: 54%), with a mean trochlear bump height of 6.1 ± 1.8 mm (range, 3.2-10.5 mm). The BPII 2.0 score increased significantly from preoperatively (29.3 ± 12.4) to postoperatively (71.8 ± 17.4) (P < .001), with a large effect size (Cohen d = -2.41). There was 1 redislocation (1.6%) and 3 reoperations (4.8%). Persistent apprehension and the J-sign were present in 8.5% and 13.6% of the knees, respectively. Multiple linear regression analysis demonstrated no statistically significant predictive relationship between the 24-month postoperative BPII 2.0 score and the preoperative BPII 2.0 score, tibiofemoral rotation, the Beighton score, or trochlear bump height (R = 0.47; R2 = 0.22; F = 5.23; P = .13).

CONCLUSION

Thin flap trochleoplasty combined with MPFL reconstruction in patients with recurrent LPI and high-grade trochlear dysplasia resulted in low redislocation and reoperation rates at a mean of 33 months. Disease-specific QOL scores were statistically significantly improved from preoperatively to postoperatively.

Preoperative subjective assessment of disease-specific quality of life significantly influenced the likelihood of achieving the minimal clinically important difference after surgical stabilization for recurrent lateral patellar instability

PURPOSE

To evaluate which factors exert a predictive value for not reaching the minimal clinically important difference (MCID) in patients who underwent a tailored operative treatment for recurrent lateral patellar dislocation (RLPD).

METHODS

A total of 237 patients (male/female 71/166; 22.4 ± 6.8 years) were included. The Banff Patellofemoral Instability Instrument 2.0 (BPII 2.0) and subjective rating of knee function and pain (numeric analogue scale [NAS]; 0-10) were used to evaluate patients' outcomes from pre- to postoperatively. Gender, age at the time of surgery, body mass index (BMI), nicotine abuse, psychiatric diseases, cartilage status and pathoanatomic risk factors were evaluated as potential predictors for achieving the MCID using univariate logistic regression analysis.

RESULTS

The MCID for the BPII 2.0 was calculated at 9.5 points. Although the BPII 2.0 and NAS for knee function and pain improved significantly in the total cohort from pre- to postoperatively (all p < 0.001), 29 patients did not reach the MCID at the final follow-up. The analysis yielded that only the preoperative NAS for function and BPII 2.0 score values were significant predictors for reaching the MCID postoperatively. The optimal threshold was calculated at 7 (NAS function) and 65.2 points (BPII 2.0). Age at the time of surgery should be considered for patients with a preoperative BPII 2.0 score >62.5.

CONCLUSION

The probability of reaching BPII 2.0 MCID postoperatively depends only on the preoperative BPII 2.0 value and subjective rating of knee function, as well as age at the time of surgery for patients undergoing surgical treatment of RLPD. Here, presented results can assist clinicians in advising and presenting patients with potential outcomes following treatment for this often complex and multifactorial pathology.

LEVEL OF EVIDENCE

Level III.

Sulcus-Deepening Trochleoplasty for High-Grade Trochlear Dysplasia: Demystifying the Procedure-a Review of the Current Literature

PURPOSE OF REVIEW

The most common and biomechanically influential pathoanatomic risk factor for recurrent patellofemoral instability is trochlear dysplasia. Sulcus-deepening trochleoplasty is a procedure developed to address high-grade trochlear dysplasia in the setting of patellofemoral instability. The purpose of this paper is to outline the current classification and surgical management of trochlear dysplasia as well as to review the current literature on the clinical outcomes and complications of sulcus-deepening trochleoplasty.

RECENT FINDINGS

This review outlines the most recent literature reporting evidence behind the decision-making to perform a trochleoplasty in the setting of patellofemoral instability and high-grade trochlear dysplasia. Critical parameters include grade of trochlear dysplasia, severity of symptoms, pertinent physical examination findings, surgical techniques, modifications for skeletally immature patients, and considerations for the revision setting. Historic studies have elicited concerns regarding high reported complication rates for trochleoplasty; however, recent studies consistently report good clinical outcomes and acceptable complication rates, similar to those of other patellar stabilizing procedures. The addition of a trochleoplasty in patients with high-grade dysplasia results in a lower re-dislocation rate, significant improvements in patient-reported outcome measures (PROMs) as well as high levels of patient satisfaction and return to sport. The use of sulcus-deepening trochleoplasty for the treatment of high-grade dysplasia and recurrent patellofemoral instability is a well-established technique with good outcomes and an acceptable complication profile. In patients with high-grade dysplasia, trochleoplasty results in lower re-dislocation rates, high patient satisfaction scores, and good clinical and functional outcomes. An understanding of trochleoplasty and its indications should be in the armamentarium of surgeons treating patellofemoral instability.

Isolated medial patellofemoral ligament reconstruction is valid to stabilize patellofemoral joint but uncertain to reduce patellar height in setting of lateral patellar dislocation and patella alta

INTRODUCTION

Medial patellofemoral ligament reconstruction (MPFLR) is the most commonly used surgical treatment for patients with lateral patellar dislocation (LPD). It is still poorly understood whether or not MPFLR has a contributory effect on decreasing patellar height.

MATERIALS AND METHODS

Forty-five patients who underwent isolated MPFLR for LPD and patella alta were evaluated with a mean follow-up period of 24 months (22-25 months). Knee joint functions were evaluated by Banff patellofemoral instability instrument (BPII) 2.0 scores and Kujala scores. Patellofemoral engagement and stability were assessed by the patella tilt angle (PTA) and patellar congruence angle (PCA) measured by CT scans, and the patellar-glide test. Patellar height was calculated on lateral radiographs according to three methods: Caton-Deschamps ratios (CDR), Insall-Salvati ratios (ISR), and Blackburne-Peel ratios (BPR). A threshold value of p < 0.05 denoted a statistically significant difference.

RESULTS

Significant improvements were found in both BPII 2.0 scores, which increased from 41.7 to 77.8 (p < 0.001) and Kujala scores, which increased from 49.2 to 85.5 (p < 0.001). Post-operative PTAs and PCA decreased from 19.6 ± 8.8 to - 3.4 ± 6.2, and from 24.6 ± 7.3 to 13.1 ± 3.8 degrees respectively (p < 0.001). No patients showed lateral translation more than grade II in the patellar-glide test. Regarding patellar height, a tiny reduction (Δ = 0.02, Δ _max = 0.09) was discovered in using CDR (p = 0.027), rather than ISR or BPR. All measurements of radiographic indices had an excellent intra- and inter-rater reliability (ICC > 0.75).

CONCLUSIONS

Isolated anatomic MPFLR is sufficient to achieve good clinical outcomes, as well as patellofemoral stability and high rates of return-to-sport. However, it is unclear if the reconstructed MPFL has a contributory effect on reducing patellar height.

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.

Soft-tissue fixation is not inferior to suture-anchor fixation in reconstruction of the medial patellofemoral ligament using a nonresorbable suture tape

PURPOSE

Reconstruction of the medial patellofemoral ligament (MPFL-R) with nonresorbable suture tape (FiberTape^®, FT) is becoming popular. Patella-side fixation of the FT can be performed with suture anchors or via soft-tissue fixation. The aim of this study was to investigate whether patella-side soft-tissue fixation can achieve equivalent primary stability compared to suture-anchor fixation.

METHODS

In ten human, fresh-frozen knee joint specimens (m/f 6/4; age 74 ± 9 a), the MPFL was identified and dissected near the femoral insertion site. In five knee joints, the MPFL-R using FT was performed with soft-tissue fixation at the patella (study group; SG), and in five knee joints, the FT was fixed via suture anchors (control group, CG). All reconstructions were evaluated until load to failure of the patella-side fixation with a displacement rate of 200 mm/min.

RESULTS

The mean maximum load to failure in the SG was 395.3 ± 57.9 N. All reconstructions failed by complete tearing off the medial patellar retinaculum from its medial patellar margin, but fixation of the FT remained stable. In the CG, the mean maximum load to failure was 239.4 ± 54.5 N and was significantly different compared to the SG (p = 0.04). All reconstructions failed via pullout of the suture anchors. Stiffness and elongation did not differ between the groups, and no failure of the FT was observed in any of the specimens.

CONCLUSION

Primary stability of soft-tissue MPFL-R using FT was superior to suture-anchor fixation. Both fixation techniques provided sufficient primary stability, superior to previously reported native MPFL tensile strengths. MPFL-R with FT could be a possible alternative procedure for MPFL-R, eliminating potential complications due to autologous tendon graft harvesting.

Medial patellofemoral ligament reconstruction using nonresorbable sutures yields comparable outcomes to reconstruction with a pedicled quadriceps tendon autograft when performed in addition to bony risk factor correction

PURPOSE

To evaluate the results for reconstruction of the medial patellofemoral ligament using synthetic nonresorbable sutures (S-MPFL-R) in comparison to MPFL-R using quadriceps tendon autograft (QT-MPFL-R) in patients undergoing simultaneous correction of anatomic risk factors for lateral patellar instability (LPI) at a minimum of 2 years of follow-up.

METHODS

Between November 2018 and June 2019, 19 patients (male/female 8/11; mean age 26 ± 7 years) underwent S-MPFL-R (FiberTape^®) in combination with the correction of predisposing risk factors for LPI. The control group of 38 patients (male/female 16/22, mean age 26 ± 6 years) who underwent QT-MPFL-R was matched 1:2 by sex, age, anatomic risk factors, and concomitant surgical correction of bony risk factors. The Banff Patella Instability Instrument 2.0 (BPII 2.0) and a numerical analog scale (NAS 0-10) for patellofemoral pain and subjective knee joint function were used to assess patients' reported quality of life before and after surgery.

RESULTS

The BPII 2.0 score increased from 35.0 ± 21.7 points to 79.7 ± 13.3 points (p < 0.0001) in the S-MPRL-R group and from 44.3 ± 19.6 points to 80.9 ± 15 points (p < 0.0001) in the QT-MPFL-R group from preoperatively to postoperatively, respectively, without any significant difference between the groups. In the S-MPFL-R group and QT-MPFL-R group, 95% (18/19) and 92% (35/38) of patients, respectively, crossed the minimally clinically important difference reported for the BPII 2.0. NAS values for pain and subjective knee joint function improved significantly in both groups (p < 0.0001, p < 0.0001) without any significant difference between the groups at the final follow-up.

CONCLUSIONS

This study demonstrates that nonresorbable sutures can serve as a viable option for MPFL-R, yielding comparable outcomes compared to quadriceps tendon autograft reconstruction when performed concomitantly with the correction of anatomic risk factors for LPI. This option reduces the need for autologous tendon harvesting or the use of allografts for MPFL-R.

LEVEL OF EVIDENCE

Level III.

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.

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.

The Influence of Surgical Realignment Procedures on Dynamic Patellar Tracking: A Dynamic Magnetic Resonance Imaging-Controlled Feasibility Study

Persisting patellar maltracking following surgical realignment often remains unseen. The aim of this study was to analyze the effects of realignment procedures on patellofemoral kinematics in patients with patellofemoral instability (PFI) and patellofemoral maltracking (PM) by using dynamic magnetic resonance imaging (MRI). Patients planned for surgical patellar realignment due to PFI and a clinically and radiologically apparent PM between December 2019 and May 2022 were included. Patients without PM, limited range of motion, joint effusion, or concomitant injuries were excluded. Dynamic mediolateral translation (dMPT) and patella tilt (dPT) were measured preoperatively and three months postoperatively. In 24 patients (7 men, 17 women; mean age 23.0 years), 10 tibial tubercle transfers, 5 soft tissue patella tendon transfers, 6 trochleoplasties, 3 lateral lengthenings, 1 varizating distal femoral osteotomy (DFO), and 1 torsional DFO were performed. At final follow-up, dMPT (from 10.95 ± 5.93 mm to 4.89 ± 0.40 mm, p < 0.001) and dPT (from 14.50° ± 10.33° to 8.44° ± 7.46°, p = 0.026) were significantly improved. All static radiological parameters were corrected to physiological values. Surgical patellar realignment contributed to the significant improvement of patellofemoral kinematics, with an approximation to normal values. The postoperative application of dynamic MRI allowed for a quantification of the performed correction, allowing for a postoperative control of success.

Combined distal femoral osteotomy and tibial tuberosity distalization is effective in patients presenting with patellar instability and patellofemoral pain due to patella alta and femoral malalignment

INTRODUCTION

Patellar malalignment has been considered one of the major pathomechanical causes of patellofemoral instability and pain. The results have been reported after femoral varization/torsional osteotomy and tibial tuberosity distalization osteotomy (TTD-O). However, the combination of a femoral deformity (genu valgum/increased femur antetorsion) and patella alta remains underreported. Therefore, the aim of this study was to investigate the clinical outcomes of patients simultaneously treated by distal femoral osteotomy and TTD-O. The hypothesis was that restoration of patellofemoral (PF) alignment via the abovementioned osteotomies would achieve good patient-reported outcome measures.

MATERIALS AND METHODS

Between 2016 and 2019, a series of 25 knees in 20 patients were treated by a distal femoral osteotomy combined with a TTD-O aiming to correct patellofemoral malalignment consisting of genu valgum and/or increased femur antetorsion and patella alta. Six patients were lost to follow-up, and one patient refused to participate. Thus, 17 knees in 13 patients (male/female 1/12; age 27.4 ± 5.4 years) were included and comprised the study group for this investigation. Patients were evaluated after a mean of 3.1 ± 0.9 years postoperatively. The Kujala anterior knee pain scale and the PF-subscale of the Knee Osteoarthritis and Outcome score (KOOS-PF) were used to assess patients' reported outcome measures from pre- to postoperatively.

RESULTS

The mean amount of torsional correction, valgus correction, and tibial tuberosity distalization averaged 14° (10°-18°), 5.2° (3.8°-8°), and 9 mm (6°-15 mm), respectively. The Kujala score increased by an average of 24.18 points from a mean of 66.6 ± 18.3 points (34-93 points) preoperatively to 90.8 ± 14.2 points (44-100 points) postoperatively (95% CI - 33.0 to - 15.3; p < 0.0001). The KOOS-PF score increased by an average of 33.7 points from a mean of 49.5 ± 24.5 points (9.1-88.6 points) preoperatively to 83.2 ± 21.6 points (15.9 -100 points) postoperatively (95% CI - 47.5 to - 19.9; p < 0.0001).

CONCLUSION

The findings of this study indicate that the combination of a distal femoral osteotomy and a tibial tuberosity distalization osteotomy is effective in patients presenting with patellar instability and patellofemoral pain due to patella alta and femoral malalignment.

Insall proximal realignment with/without tibial tubercle osteotomy for recurrent patellar instability yields acceptable medium- to long-term results but risk of osteoarthritis progression is considerable

PURPOSE

The purpose of this study was to evaluate clinical and radiological results in patients operated for recurrent patellar instability with a surgical approach consisting of Insall proximal realignment with/without tibial tubercle osteotomy (TTO).

METHODS

Patients that underwent surgery for recurrent patellar instability at one centre with a uniform technique between 2004 and 2020 were included. Eligible patients were assessed by clinical examination and the disease-specific Banff Patellofemoral Instability Instrument 2.0 (BPII 2.0). Pre- and postoperative radiographs were analysed for patellofemoral osteoarthritis (OA) according to Iwano. Preoperative Magnetic Resonance Imaging (MRI) and radiographs were analysed for anatomical risk factors for patellar instability. Student t-test, chi-square test and ANOVA-analyses were used to investigate whether anatomical risk factors and/or patient characteristics could predict an inferior outcome.

RESULTS

Forty-six patients (47 knees) were included at a mean follow-up time of 6.6 years (SD 4.6; range 1-17). Mean BPII 2.0 score was 60.4 (SD 18.4; range 26-98), and 10.6% (n = 5) had suffered a postoperative redislocation. Progression to evident patellofemoral OA was seen in 15% of the patients (p < 0.05). The presence of pathoanatomic risk factors did not correlate with recurrent postoperative instability or inferior BPII 2.0 score at the final evaluation.

CONCLUSION

Patients treated with the current approach reported acceptable medium- to long-term results, but the risk of patellofemoral OA progression is significant. These findings add to the knowledge of expected outcomes after procedures involving Insall proximal realignment, and can guide clinical decision making for surgeons using similar methods.

LEVEL OF EVIDENCE

Level IV, case series.

Mental and physical health-related quality of life in patients with recurrent patellar dislocations-a generic and disease-specific quality of life questionnaire assessment

Purpose

There is a paucity of quality of life (QoL) assessments in studies evaluating patients treated for recurrent lateral patellar dislocation (LPD). The primary aim of this study was to investigate whether mental well-being is impaired in patients with chronic (recurrent) LPD and, if so, to assess whether the mental health-related QoL dimension improves equivalently to the physical-related QoL dimension after successful surgical treatment.

Methods

Thirty-eight patients with recurrent LPD over a mean course of the disease of 4.7 ± 3.9 years (1—18 years) prior to surgery were included. Generic health-related QoL (HRQoL) (Short Form 36; SF-36) and disease-specific QoL (Banff Patella Instability Instrument 2.0; BPII 2.0) were assessed preoperatively and after a mean follow-up of 3.5 ± 0.8 years (2 – 5 years) postoperatively.

Results

Untreated LPD significantly impacted the physical dimension of patients’ generic HRQoL and their disease-specific QoL. When compared to age-equivalent normative data sets, the mental HRQoL dimension was not reduced prior to operative treatment but increased during the follow-up period. Surgical treatment normalized the physical dimension of patients’ generic HRQoL and significantly improved their disease-specific QoL. However, BPII 2.0 values remained reduced, albeit patellae were successfully stabilized.

Conclusion

The results of this study indicate that patients with recurrent LPD are generally in good mental health, although physical impairment is striking. Notwithstanding that surgery prevented further dislocations and normalized the generic HRQoL, the disease-specific QoL remained reduced as far as this can be interpreted without population-based data.

Level of evidence

Level IV; Retrospective case series.

Influence of the Fluoroscopy Setting towards the Patient When Identifying the MPFL Insertion Point

(1) The malposition of the femoral tunnel in medial patellofemoral ligament (MPFL) reconstruction can lead to length changes in the MPFL graft, and an increase in medial peak pressure in the patellofemoral joint. It is the cause of 36% of all MPFL revisions. According to Schöttle et al., the creation of the drill canal should be performed in a strictly lateral radiograph. In this study, it was hypothesized that positioning the image receptor to the knee during intraoperative fluoroscopy would lead to a relevant mispositioning of the femoral tunnel, despite an always adjusted true-lateral view. (2) A total of 10 distal femurs were created from 10 knee CT scans using a 3D printer. First, true-lateral fluoroscopies were taken from lateral to medial at a 25 cm (LM25) distance from the image receptor, then from medial to lateral at a 5 cm (ML5) distance. Using the method from Schöttle, the femoral origin of the MPFL was determined when the femur was positioned distally, proximally, superiorly, and inferiorly to the image receptor. (3) The comparison of the selected MPFL insertion points according to Schöttle et al. revealed that the initial determination of the point in the ML5 view resulted in a distal and posterior shift of the point by 5.3 mm ± 1.2 mm when the point was checked in the LM25 view. In the opposite case, when the MPFL insertion was initially determined in the LM25 view and then redetermined in the ML5 view, there was a shift of 4.8 mm ± 2.2 mm anteriorly and proximally. The further positioning of the femur (distal, proximal, superior, and inferior) showed no relevant influence. (4) For fluoroscopic identification of the femoral MPFL, according to Schöttle et al., attention should be paid to the position of the fluoroscopy in addition to a true-lateral view.

Revision surgery for failed medial patellofemoral ligament reconstruction results in better disease-specific outcome scores when performed for recurrent instability than for patellofemoral pain or limited range of motion

PURPOSE

Medial patellofemoral ligament reconstruction (MPFL-R) is an important treatment for recurrent patellar instability. Although complications such as redislocation, patellofemoral pain (PFP) and restricted knee range of motion have been reported, few studies have investigated the results of revision surgery for failed MPFL-R. Thus, the aim of this study was to determine the results of the tailored revision surgery after considering the cause of the reconstruction failure.

MATERIALS AND METHODS

Between 2015 and 2019, 28 patients (male/female 9/19; age 26.2 ± 6.4 years) underwent revision surgery for failed MPFL-R. The patients were grouped into the "recurrent instability" (SG1) group and "PFP" and/or "restricted range of motion" (SG2) group. Preoperatively, the clinical data, anatomical risk factor profile, and position of the femoral MPFL tunnel were determined for each patient. The Banff Patella Instability Instrument 2.0 (BPII 2.0) and numerical analogue scale (NAS 0-10) were administered preoperatively and at the final follow-up for the subjective assessment of the PFP and knee joint function.

RESULTS

Overall, the BPII 2.0 score improved from 28.8 ± 16.6 points preoperatively to 68.0 ± 22.7 points (p < 0.0001) postoperatively. SG1 exhibited an increase in the BPII 2.0 score from 28.9 ± 20.2 points to 75.7 ± 23 points (p < 0.0001). PFP decreased from 6.8 ± 2.4 to 1.6 ± 1.9 (p < 0.0001), while the knee joint function increased from 4.3 ± 2.5 to 8.8 ± 1.6 (p < 0.0001). In SG2, the BPII 2.0 score increased from 28.7 ± 12.6 points preoperatively to 57.7 ± 19.7 points (p = 0.0002) postoperatively and was thus significantly lower than that in SG1 (p = 0.038). The intensity of PFP decreased from 6.6 ± 3.0 preoperatively to 2.1 ± 1.9 postoperatively (p = 0.0006), while the subjective knee joint function improved from 3.2 ± 1.4 preoperatively to 7.6 ± 2.3 postoperatively (p < 0.0001). The differences between the groups were not significant.

CONCLUSION

Tailored revision surgery for failed MPFL-R significantly improves the patient-reported disease-specific quality of life. The study results indicate that patients undergoing revision surgery as a consequence of patellar redislocation appear to benefit more from revision surgery than those patients undergoing revision due to postoperative PFP and/or a limited knee joint range of motion.

LEVEL OF EVIDENCE

Level IV.

The J-sign and the body mass index determine the disease-specific quality of life in patients with lateral patellar instability

PURPOSE

To determine which risk factors for patellar instability contribute most relevantly to patients' subjective disease-specific quality of life, aiming to provide implications on the overall treatment decision-making process.

METHODS

A total of 182 consecutive patients (male/female 70/112; mean age 23.6 ± 7.3 years) with a history of patellar instability were prospectively enrolled in this study. Patient age, body mass index (BMI), number of dislocations, reversed dynamic patellar apprehension test (ReDPAT), J-sign severity, and pathoanatomic risk factors of patellar instability were assessed. The statistical analysis evaluated the relationships among those variables and determined their ability to predict the Banff Patellofemoral Instability Instrument 2.0 (BPII 2.0) as a disease-specific quality of life measure. Using Spearman correlation, ANOVA and Fisher's exact test, all variables with ANOVA p ≤ 0.1 or Spearman's abs (rho) > 0.1 were entered into a multivariate linear model using backward-stepwise selection.

RESULTS

Analysis of the individual variables' ability to predict BPII 2.0 score values revealed 'age', 'BMI', 'ReDPAT', 'high grade of trochlear dysplasia', and 'high-grade J-Sign' as possible relevant factors. Backward-stepwise multivariate regression analysis yielded a final parsimonious model that included the factors 'BMI' and 'J-Sign (Grade II and III)' as the most relevant parameters influencing BPII 2.0 score values (adjusted R² = 0.418; p < 0.001), with a cutoff value for BMI found at 28 kg/m² (p = 0.01).

CONCLUSION

The results of this study indicate that in patients with lateral patellar instability, a high-grade J-sign and an increased BMI significantly impact subjective disease-specific quality of life.

LEVEL OF EVIDENCE

Level IV.

Return to Sports and Patients' Rehabilitation Continuum After Deepening Trochleoplasty and Concomitant Patellar-Stabilizing Procedures: A Case Series of 111 Patients at 2 to 4 Years of Follow-up

BACKGROUND

There are few reports on the return to sports after complex patellar-stabilizing surgery.

PURPOSES

To evaluate patients' ability to return to sports and to investigate the extent to which the preoperative level of sports participation influences sports activity after deepening trochleoplasty (TP) and concomitant patellar-stabilizing procedures.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Between April 2015 and April 2019, 144 patellar-stabilizing procedures, including deepening TP and medial patellofemoral ligament reconstruction or medial reefing with and without concomitant realignment procedures, were carried out in 142 patients. The Banff Patellofemoral Instability Instrument 2.0 (BPII 2.0) and the Tegner activity score were used to assess patients' quality of life and sports activity level. In addition, a numerical analog scale was used to evaluate patellofemoral pain intensity during rest and activity and subjective knee joint function.

RESULTS

Outcomes were available for 111 patients (112 knees) (male/female, 77/34; mean age, 23.4 ± 7.8 years), yielding a 77.7% follow-up rate at a mean of 39.2 ± 9.9 months (range, 24-48 months). Two-thirds of the patients returned to their preoperative level of activity or higher, but their Tegner scores did not change significantly (4.5 ± 2.4 vs 4.7 ± 1.6; P = .365). Low-level athletes (preoperative Tegner score 0-4) participated at a higher level of sports activity (2.7 ± 1.4 to 4.1 ± 1.2; P < .0001), whereas higher-level athletes (preoperative Tegner score 5-10) participated at a lower level (6.8 ± 1.3 to 5.5 ± 1.7; P < .0001). The likelihood of returning to the preoperative activity level (Tegner score) was significantly higher in the low-level activity group than in the high-level activity group (P = .0001; 95% CI, 4.055-27.05; odds ratio, 10.47). All of the patient-reported outcome measures improved postoperatively, independent of the patients' age, sex, and body mass index.

CONCLUSION

Patients undergoing deepening TP and medial soft tissue stabilization with or without concomitant realignment surgery for complex patellar instability can expect good clinical results and a high rate of return to sports participation, with two-thirds of patients returning to their preoperative Tegner-level of activity or higher. However, higher-level athletes should be informed that their likelihood of returning to sports at the preoperative level or full participation at a competitive level is reduced.

[Primary and recurrent patellar dislocation: recommendation for diagnostic evaluation, risk stratification and treatment]

The dogma that (every) primary patellar dislocation should be treated non-operatively is considered outdated. Therefore, every first-time dislocation, as well as every recurrent dislocation, should be fully diagnosed with regard to the injury pattern and anatomically predisposing risk factors. This enables the use of risk stratification models to assess the risk of recurrent episodes of instability, thereby supporting the clinical decision-making process. The reconstruction of the MPFL can be considered an established and successful treatment strategy for patellar instability. However, the additional correction of bony risk factors is often useful. In this context, the preoperative grading of the J sign and dynamic assessment of patellar instability (dynamic apprehension test) are of utmost importance. These findings, combined with the radiographic imaging findings, can be used as a clinical decision aid for a bony correction procedure.