Quadriceps muscle contraction causes medial patellofemoral ligament elongation by intermeshed fibers of vastus medialis oblique muscle.

The first aim of this study was to compare the medial patellofemoral length between contracted and relaxed quadriceps muscle and second to assess the importance of the intermeshed vastus medialis oblique fibers. After a priori power analysis (α = 0.05, power [1-ß] = 0.95), 35 healthy males aged 18-30 were prospectively examined with a 3.0-T magnetic resonance imaging (MRI) scanner in 10-15° of knee flexion. Two axial MRI sequences (25 s each) were made with relaxed and contracted quadriceps. Two blinded, independent raters measured twice medial patellofemoral ligament length (curved line) and attachment-to-attachment length (straight line). Mean medial patellofemoral ligament length and attachment-to-attachment length with relaxed quadriceps was: 65.5 mm (SD = 3.7), 59.7 mm (SD = 3.6), and after contraction, it increased to 68.7 mm (SD = 5.3), 61.2 mm (SD = 4.7); p < 0.01 and <0.001, respectively. Intraclass correlation coefficients for intra- and inter-rater reliabilities ranged from 0.55 (moderate) to 0.97 (excellent). Mean medial patellofemoral ligament length elongation after quadriceps contraction was significantly greater (3.2 mm, SD = 3.9) than mean attachment-to-attachment length elongation (1.6 mm, SD = 2.8); p < 0.001. Contraction of quadriceps muscle causes elongation of the medial patellofemoral ligament to the extent greater than the elongation of distance between its attachments. This confirms that medial patellofemoral ligament elongation after quadriceps contraction results not only from movement of its patellar attachment but also directly from intermeshed vastus medialis oblique fibers pulling medial patellofemoral ligament in a different direction creating a bow-like construct in agreement with the "pull-and-guide mechanism" proposed in the literature.

Arthroscopic medial patellofemoral ligament reconstruction with polyethylene suture combined with medial retinaculum plication for the treatment of acute patellar dislocation in young and middle-aged patients with a follow-up of at least 2 years.

PURPOSE: The purpose of this study was to propose a surgical technique for arthroscopic medial patellofemoral ligament (MPFL) reconstruction with polyethylene suture combined with medial retinaculum plication and to evaluate the efficacy of this surgical technique in the treatment of acute patellar dislocation. METHODS: Clinical data of patients with acute patellar dislocations treated with arthroscopic MPFL reconstruction with polyethylene tape (FiberTape) combined with medial support band compression were analyzed retrospectively from January 2018 to January 2021. The mean age of the patients was 25.15 ± 4.66 years; the mean follow-up time was 27.5 (24-36) months. Clinical evaluation consisted of apprehension test results, patellar extrapolation test results, Lysholm score, Kujala score, and IKDC score, the Patellar lateral shift distance and patellar tilt angle (PTA) measured by CT scan. RESULTS: All patients had no recurrent patellar dislocation or subluxation after surgery, and the apprehension test was negative. In all patients, the Kujala score (36.0 ± 9.9 vs. 98.2 ± 3.1), the IKDC score (48.6 ± 7.0 vs. 90.6 ± 4.4) and the Lysholm score (32.8 ± 10.4 vs. 96.7 ± 3.1) had improved at the 24-month follow up (P < 0.05). In addition, PTA was significantly lower at the 12-month follow-up and 24-giving-month follow-up compared to the preoperative period (P < 0.05, Table 2). The patellar lateral shift distance decreased from 14.94 ± 6.11 mm preoperatively to 3.00 ± 1.40 mm (12-month follow up) and 3.26 ± 1.37 mm (24-month follow up), respectively. CONCLUSION: Arthroscopic MPFL reconstruction with polyethylene suture combined with medial retinaculum plication is a safe and reliable surgical technique for the treatment of acute patellar dislocation in young and middle-aged patients. LEVEL OF EVIDENCE: Level III, Therapeutic Study.

Three different patellar fixation techniques yield similar clinical and radiological outcomes in recurrent patellar dislocation undergoing medial patellofemoral ligament reconstruction.

PURPOSE: The purpose of this study was to evaluate and compare the clinical and radiological outcomes of three different patellar fixation techniques on medial patellofemoral ligament reconstruction (MPFLR) in the treatment of patellar dislocation (PD). METHODS: Between 2015 and 2020, 130 patients with recurrent PD who underwent surgical reconstruction were eligible for this retrospective study: 48 patients were treated with the semi-tunnel bone bridge fixation technique (Group A), 42 patients were treated with the suture anchor fixation technique (Group B) and 40 patients were treated with the transpatellar tunnel fixation technique (Group C). Clinical outcomes included functional outcomes (Kujala, Lysholm and International Knee Documentation Committee scores), activity levels (Tegner activity score and return to sports), physical examinations, patellar re-dislocation rate and complications. Radiological outcomes included patellar congruence angle, patellar tilt angle, lateral patellar translation and lateral patellar angle. RESULTS: All clinical and radiological outcomes improved significantly in all groups, without any significant difference among these three groups. At the final follow-up, no re-dislocation occurred, and all groups achieved a successful return to sports. However, the semi-tunnel bone bridge and suture anchor fixation techniques showed statistically higher Tegner activity scores (p = 0.004) and shorter time from surgery to return to sports (p = 0.007) than the transpatellar tunnel fixation technique. CONCLUSION: The three MPFLR patellar fixation techniques achieved favourable and comparable clinical and radiological outcomes in the treatment of PD. Compared with the transpatellar tunnel fixation technique, the semi-tunnel bone bridge and suture anchor fixation techniques may be more effective with higher activity levels. LEVEL OF EVIDENCE: Level III.

Lateral to medial fluoroscopic view improves the accuracy of identifying the MPFL femoral footprint using Schottle's technique.

PURPOSE: This study investigated the effect of different fluoroscopy settings on the accuracy of locating Schottle's point during medial patellofemoral ligament (MPFL) reconstruction. METHODS: The centre of the MPFL femoral footprint was identified and marked on 44 dry femurs. Two standard true lateral knee fluoroscopic images were obtained: (1) medial to lateral (ML) and (2) lateral to medial (LM). The deviation between the anatomically determined MPFL femoral footprint and the fluoroscopically identified point was measured on both fluoroscopic images. An 'acceptable tunnel location' was defined as within a 5- or 7-mm margin of error from the anatomic MPFL footprint. Distal femoral morphometric dimensions were also measured using digital calipers. Statistical analysis determined discrepancies between techniques and their relation to femoral morphometry. RESULTS: The LM view yielded a significantly smaller distance between the anatomical MPFL footprint and Schottle's point compared to the ML view (3.2 ± 1.5 vs. 4.5 ± 2.1 mm, p < 0.001). The LM view achieved acceptable tunnel locations, meeting the 5-mm error criterion in 90.9% of cases, while the ML view achieved 65.9% (p < 0.001). Both views yielded acceptable tunnel locations at similar rates using the 7-mm error criterion (n.s.). The anatomic MPFL footprint was displaced towards the anterior and proximal location in the ML view in reference to the Schottle point. No correlation was observed between any of the morphometric measurements and the deviations. CONCLUSIONS: This study demonstrated that using the LM fluoroscopic view improves the accuracy of femoral tunnel placement when identifying the MPFL footprint via the Schottle technique. Adopting the LM view in surgical practice will help surgeons locate the anatomical femoral footprint accurately, replicating the native MPFL and enhancing clinical outcomes. LEVEL OF EVIDENCE: Level 4, cadaveric study.

Simultaneous MPFL reconstruction and guided growth result in low rates of recurrent patellofemoral instability.

PURPOSE: Implant-mediated guided growth (IMGG) is used to address coronal plane deformity in skeletally immature patients. Few studies have reported on IMGG and simultaneous medial patellofemoral ligament (MPFL) reconstruction for paediatric patients with concurrent genu valgum and patellofemoral instability (PFI). This study aimed to report on the outcomes of these simultaneous procedures. MATERIALS AND METHODS: This was a retrospective review of paediatric patients undergoing simultaneous MPFL reconstruction and IMGG between 2016 and 2023. Mechanical lateral distal femoral angle (mLDFA), hip-knee-ankle angle (HKA) and mechanical axis deviation (MAD) were measured on full-length hip-to-ankle plain radiographs. Measurements were taken preoperatively, prior to implant removal and/or at final follow-up with minimum 1-year clinical follow-up. RESULTS: A total of 25 extremities in 22 patients (10 female) underwent simultaneous IMGG and MPFL reconstruction. The mean age at surgery was 12.6 ± 1.7 years. The mean duration of implant retention was 18.6 ± 11.3 months. Nineteen extremities (76%) underwent implant removal by final follow-up. Preoperative HKA corrected from a mean of 5.8 ± 2.3° to -0.8 ± 4.5° at implant removal or final follow-up (p < 0.001), with mLDFA and MAD similarly improving (both p < 0.001). HKA corrected a mean of 0.7 ± 0.9° per month, while mLDFA and MAD corrected a mean of 0.5 ± 0.6°/month and 2 ± 3 mm/month, respectively. At the time of implant removal or final follow-up, 88% of patients demonstrated alignment within 5° of neutral. Only one extremity experienced subsequent PFI (4%). For 14 patients who underwent implant removal with further imaging at a mean of 7.8 ± 4.9 months, only one patient (7%) had a valgus rebound to an HKA > 5°. CONCLUSION: Simultaneous MPFL reconstruction and IMGG provided successful correction of lower extremity malalignment with only one recurrence of PFI. This approach is a reliable surgical option for skeletally immature patients with genu valgum and PFI. LEVEL OF EVIDENCE: Level 4 case series.

Synthetic suture tape for medial patellofemoral ligament reconstruction is an effective treatment for complex paediatric patellofemoral instability.

PURPOSE: To assess the outcomes of medial patellofemoral ligament (MPFL) reconstruction using synthetic suture tape in paediatric patients with patellofemoral instability (PFI). METHODS: This ambispective comparative study, conducted from 2014 to 2022, included paediatric patients who underwent MPFL reconstruction with synthetic suture tape and had a minimum follow-up of 1 year. Pre- and postoperative clinical and functional outcomes, patient satisfaction and complications were assessed. RESULTS: The study comprised 22 patients (29 knees), with a median age at surgery of 14.4 years (interquartile range [IQR] 10.9-16.7) and a median follow-up of 46.5 months (24.7-66). Notably, 13 knees (44.8%) had open growth plates at the time of surgery. The cohort included patients with Down syndrome (3 patients), Ehlers-Danlos (2), arthrogryposis (1), generalized joint hypermobility (8) and previous unsuccessful PFI surgeries (8). Concomitant procedures were performed on 16 knees. Postoperatively, improvements were observed in all but one patient, who reported residual pain. There were two other complications: one suture-tape rupture and one surgical wound infection. Functional scores significantly improved: Kujala, +14 points (7-29) (p < 0.001); IKDC, +10.5 points (5.2-25.3) (p < 0.001); Tegner, +2 points (0-4) (p < 0.001); Lysholm, +15 points (0-37.5) (p < 0.001). Most patients achieved excellent outcomes by Crosby-Insall criteria (21 patients, 72.4%) and reported high satisfaction (23 patients, 79.3%). CONCLUSIONS: MPFL reconstruction using synthetic suture tape is a viable and effective treatment for paediatric patients with PFI, particularly for those with connective tissue disorders, generalized joint hypermobility or past surgical failures, significantly enhancing clinical and functional outcomes with an acceptable complication rate. LEVEL OF EVIDENCE: Level IV.

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

PURPOSE: The purpose of this study is to systematically review and quantitatively analyse the clinical outcomes of combined derotational distal femoral osteotomy (D-DFO) and medial patellofemoral ligament reconstruction (MPFL-R) in the treatment of recurrent patellar dislocation (RPD) with increased femoral anteversion angle (FAA). METHODS: This study was performed in line with PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) and AMSTAR (Assessing the Methodological Quality Of Systematic Reviews) Guidelines. PubMed, Embase, Web of Science and Cochrane Library databases were searched to identify studies reporting clinical outcomes of combined D-DFO and MPFL-R in RPD patients with increased FAA. Data on patient-reported outcome measures, radiological parameters, patellar tracking as revealed by J-sign and complications were extracted based on the inclusion criteria. The Methodological Index for Non-Randomized Study score was used for quality assessment. Review Manager and R statistical software were used to perform the statistical analysis. RESULTS: Eleven studies with a total of 569 knees in 553 patients were included. Patients were predominantly female (79%). The weighted mean of FAA decreased from 33.6° to 13.0° (weighted mean difference = 20.59; p < 0.00001) after the combined procedure. Significant improvements (p < 0.00001) were identified in the Lysholm score (weighted mean: 55.5 vs. 80.4), International Knee Documentation Committee (IKDC) score (weighted mean: 52.8 vs. 78.6) and Kujala score (weighted mean: 54.5 vs. 80.6). The incidence of residual J-sign ranged from 14.3% to 38.3% with an overall pooled rate of 28.2% (95% confidence interval = 22.8%-33.6%). The overall redislocation rate was 1.1%. No patients experienced surgical site infection or bone nonunion. Two studies compared the clinical outcomes of MPFL-R with and without D-DFO. Compared with isolated MPFL-R, the combined procedure yielded a better Lysholm score (weighted mean: 84.9 vs. 79.3, p < 0.0001), IKDC score (weighted mean: 84.1 vs. 79.9, p = 0.001), Kujala score (weighted mean: 84.3 vs. 79.4, p < 0.0001) and a lower residual J-sign rate (26/97 [26.8%] vs. 44/105 [41.9%], p = 0.02), respectively. CONCLUSION: The combination of D-DFO and MPFL-R led to improved clinical outcomes and a low redislocation rate in patients with RPD and increased FAA. Additional D-DFO can achieve more favourable results in subjective function and patellar tracking than isolated MPFL-R in the setting of excessive FAA. LEVEL OF EVIDENCE: Level IV.

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.

Decreased femoral trochlea axial orientation corrected by derotational distal femur osteotomy in patients with patellar dislocation yields satisfactory outcomes.

PURPOSE: The femoral trochlea axial orientation has been shown to be a better predictor of patellar dislocation than the femoral anteversion angle. However, no study has investigated the importance of the femoral trochlea axial orientation in the surgical treatment of patellar dislocation. It is aimed to explore the pathological threshold of the femoral trochlea axial orientation and its guiding implications for surgical interventions in the study. METHODS: Sixty-four patients with patellar dislocation and 64 controls were included for measurement of the femoral trochlea axial orientation. The ability to predict the patellar dislocation and the pathologic threshold of the femoral trochlea axial orientation were evaluated using the receiver operating characteristic curve. One hundred patients with medial patellofemoral ligament reconstruction and 25 patients with derotational distal femur osteotomy were divided into two groups based on the femoral trochlea axial orientation cut-off value and their postoperative knee functions, and patellar tilt angles were compared. RESULTS: There were significant differences in the femoral trochlea axial orientation (60.8 ± 7.9 vs. 67.8 ± 4.6, p < 0.05) between patients with patellar dislocation and the normal population. The sensitivity and specificity of the femoral trochlea axial orientation were 0.641 and 0.813, respectively, at the femoral trochlea axial orientation smaller than 63.8°. Amongst patients having had isolated medial patellofemoral ligament reconstruction with decreased femoral trochlea axial orientation, knee function was poorer after surgery. The prognosis of patients with the femoral trochlea axial orientation correction in derotational distal femur osteotomy was better than that for patients without correction. CONCLUSIONS: The femoral trochlea axial orientation had good predictive efficiency for patellar dislocation. Isolated medial patellofemoral ligament reconstruction is not sufficiently effective for patients with patellar dislocation and decreased femoral trochlea axial orientation. Patients with a decreased femoral trochlea axial orientation can have better surgical outcomes after correction by derotational distal femur osteotomy. LEVEL OF EVIDENCE: Level III.

Measurement of TT-TG can change with sequential MRIs due to variations in tibiofemoral rotation in patellofemoral instability patients.

PURPOSE: There are various anatomic risk factors for patellofemoral instability (PFI) that help guide surgical treatment, including the tibial tubercle to trochlear groove (TT-TG) distance. However, no study has analysed the temporal changes in TT-TG prior to surgical intervention. This study sought to understand the variations in TT-TG over time for pediatric patients suffering from PFI prior to surgical intervention. The authors hypothesised that the TT-TG would substantially change between time points. METHODS: Patients undergoing medial patellofemoral ligament (MPFL) reconstruction between 2014 and 2019 by one of two fellowship-trained orthopaedic surgeons were identified. Patients were included if they had two preoperative magnetic resonance imaging (MRI) performed on the same knee within 7.5 months of each other prior to any surgical intervention and had an initial TT-TG greater than 10 mm. RESULTS: After considering 251 patients for inclusion, 21 patients met the final inclusion criteria. The mean age was 14.5 ± 2.5 years and 61.9% were female. TT-TG was initially noted to be 15.1 ± 1.8 mm. At mean time after sequential MRIs of 5.0 ± 1.9 months, TT-TG was noted to be 16.7 ± 3.2 mm. The differences between initial and subsequent TT-TG ranged from a 21.2% decrease to a 61.1% increase, with a mean difference of an 11.3% increase. Comparison between initial and subsequent TT-TG values demonstrated a significant difference (p = 0.017). Change in tibiofemoral rotation ranged from -9.2° to 7.5°. When comparing the change in TT-TG to change in tibiofemoral rotation, a significant correlation was found (p = 0.019). CONCLUSION: Despite only a mean time between MRIs of 5 months, variations in TT-TG ranged from a decrease of 21.2% to an increase of 61.1%. The significant relationship between the changes in TT-TG and changes in tibiofemoral rotation between MRIs suggest that TT-TG measurements may vary due to variations in tibiofemoral rotation at the time of individual MRIs. LEVEL OF EVIDENCE: Level IV.

An MRI study demonstrating consistent anatomic relation of central longitudinal artery and associated periosteal vessels with the medial femoral epicondyle and adductor tubercle-A visual landmark method for femoral tunnel placement in medial patellofemoral ligament reconstruction.

The two most common techniques to determine femoral tunnel placement during medial patellofemoral ligament (MPFL) reconstruction are radiographic and by palpation. Their intra/interobserver reliability is widely debated. Both techniques rely on identifying bony landmarks such as the medial epicondyle (ME) and adductor tubercle (AT) during surgery. During MPFL reconstructive surgery, the central longitudinal vessels (CLVs) are seen consistently. The aim of this study was to investigate the anatomic relationship of CLV to ME and AT and to determine if CLV might be used as a landmark during MPFL reconstruction. A retrospective review of MRI scans in skeletally mature patients was undertake. There were two groups, a PFI group that consisted of patients with a diagnosis of patellofemoral instabiliy (PFI) and a non-PFI group that underwent MRI scan for an alternative diagnosis. MRIs were measured for the CLV-ME-AT anatomy and relationship. Following exclusions, 50 patients were identified in each group. The CLV passed anterior to the AT and ME in all patients. ME morphology did not differ greatly between the groups except in the tubercle height, where there was statistically significant but not a clinically important difference (larger in the non-PFI group, 2.95 vs. 2.52 mm, p = 0.002). The CLV to ME tip distance was consistent between the groups (PFI group 3.8 mm and non-PFI group 3.9 mm). The CLV-ME-AT relationship remained consistent irrespective of patients' presenting pathology. The CLV consistently courses anterior to ME and AT. The CLV could be used as a vascular landmark assisting femoral tunnel placement during MPFL reconstruction.

Comparison of five different fluoroscopic methods for identifying the MPFL femoral footprint.

PURPOSE: The success of medial patellofemoral ligament (MPFL) reconstruction is closely linked to the precise positioning of the femoral tunnel. Intraoperative fluoroscopy is commonly utilized to identify the MPFL footprint. This study aimed to ascertain the most accurate fluoroscopic method among the five previously described methods used to determine the MPFL femoral footprint. MATERIALS AND METHODS: Using 44 well-preserved dry femur bones, the MPFL femoral insertion site was demarcated using anatomical bony landmarks, namely the center of the saddle sulcus between the medial epicondyle, adductor tubercle and gastrocnemius tubercle. Fluoroscopic true lateral knee images were acquired and measurements taken, referencing established methods by Schottle et al., Redfern et al., Wijdicks et al., Barnett et al., and Kaipel et al. The distance between anatomic and fluoroscopic MPFL footprints was then measured on digital fluoroscopic images. The accuracy of the locations was compared using a margin of error of 5 and 7 mm. RESULTS: The Schottle method consistently emerged superior, showcasing the smallest mean distance (3.2 ± 1.2 mm) between the anatomic and radiographic MPFL footprints and a high in-point detection rate of 90.9% under 5 mm criteria. While the Redfern method displayed perfect accuracy (100%) within the 7 mm criteria, the Schottle method also performed 97.7% accuracy. CONCLUSIONS: For intraoperative identification of the MPFL footprint using fluoroscopy, the Schottle method is the most consistent and accurate among the assessed methods. Thus, its accuracy in detecting the MPFL footprint makes it recommended for MPFLR to ensure optimal outcomes. LEVEL OF EVIDENCE: Level IV, cadaveric study.

Combination of tibial tubercle transfer, medial patellofemoral ligament reconstruction, trochleoplasty and lateral release for patellofemoral instability provides good middle- to long-term outcomes in adolescents.

PURPOSE: There are limited studies that have reported the middle- to long-term outcomes of combined procedures consisting of more than two procedures for patellofemoral instability. The current study aims to investigate and report the middle- to long-term outcomes of a combination procedure of tibial tubercle transfer, medial patellofemoral ligament reconstruction, trochleoplasty and lateral release for patellofemoral instability in patients aged 18 years and below. METHODS: In the cohort study, all patients aged 18 years old or younger who underwent a combination procedure of tibial tubercle transfer, medial patellofemoral ligament reconstruction, trochleoplasty and lateral release for recurrent patellofemoral instability were included. RESULTS: A total of 21 patients were included in the study. All patients had no further patellofemoral dislocation, pain and apprehension following the 4-in-1 surgery (p < 0.01). There was a significant improvement in the Kujala score from 36.1 (SD 12.9) pre-operatively to 93.1 (SD 3.6) post-operatively (p < 0.001). The patients also had a statistically significant improvement in their radiological factors, including the patellar tilt angle (p < 0.001), sulcus angle (p = 0.001), trochlear groove depth (p = 0.041), tibial tubercle-trochlear groove distance (p < 0.001) and Caton-Deschamps index (p = 0.001). CONCLUSION: A combination procedure of tibial tubercle transfer, medial patellofemoral ligament reconstruction, trochleoplasty and lateral release leads to good middle- to long-term subjective, functional and radiographic outcomes for patients with recurrent patellofemoral instability and underlying predisposing factors of increased TT-TG distance of more than 20 mm, Dejour B or D trochlear dysplasia and medial patellofemoral ligament rupture. LEVEL OF EVIDENCE: IV.

Differences of injury characteristics of medial patellofemoral ligament in acute lateral patellar dislocation and multiligament knee injuries.

BACKGROUND: The injury characteristics of medial patellofemoral ligament (MPFL) in multiligament knee injuries (MLKIs) and the differences of injury patterns of MPFL in MLKIs and acute lateral patellar dislocation (LPD) remain unclear. PURPOSE: To explore the differences of injury characteristics of MPFL after acute LPD and MLKIs. METHODS: Magnetic resonance images were prospectively analyzed in 219 patients after acute LPD or MLKIs. Statistical analyses of the injury patterns of MPFL were performed between LPD and MLKIs. RESULTS: The incidence of partial tear and complete MPFL tear in adolescent LPD and MLKIs were 40.3% and 48.4%, and 27.9% and 16.3%, respectively. Compared with LPD, MLKIs showed lower incidence rates of partial and complete MPFL tears (both P = 0). The MLKI subgroup showed lower incidence rates of MPFL tear at the patellar insertion (PAT), femoral attachment (FEM), and multiple-site of the MPFL (COM) (9.3%, 20.9%, and 14%) when compared with the LPD subgroup (45.2%, 24.2%, and 16.1%) (all P < 0.01). The incidence of partial tear and complete MPFL tear in adult LPD and MLKIs were 41.5% and 47.2%, and 24.6% and 16.4%, respectively. Compared with LPD, MLKIs showed lower incidence rates of partial and complete MPFL tears (both P = 0). The MLKI subgroup showed lower incidence rates of MPFL tear at PAT, FEM, and COM (8.2%, 18%, and 14.8%) when compared with the LPD subgroup (20.8%, 34%, and 30.2%) (all P = 0). CONCLUSION: Compared with LPD, MPFL tears are relatively uncommon in MLKIs. Even if MPFL tears occur, partial tears and femoral-sided tears are relatively more common.

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

OBJECTIVE: A combination of lateral soft tissue release, medial soft tissue contraction, vastus medialis anterior placement, medial patellofemoral ligament reconstruction, and rectus femoris insertion reconstruction are introduced in the treatment of habitual patellar dislocation in adolescents. METHODS: A retrospective analysis was performed on 12 patients (17 knees) with habitual patellar dislocation and unclosed epiphyses who underwent surgical treatment at the First Hospital of Jilin University from May 2017 to November 2021. The Lysholm scores and Q angle were collected preoperatively and at final follow-up and were compared. RESULTS: Twelve patients (4 boys and 8 girls) aged 10-15 years were retrospectively analysed, who followed up for an average of 21 months (5-48 months). The range of motion of the knee joint returned to normal in all patients, and no cases of complications including surgical site infection, joint stiffness, or patellar re-dislocation occurred. The mean Lysholm scores and Q angles improved from 73.9, and 19.6° preoperatively to 91.7, and 13.9° at the final follow-up, respectively. CONCLUSION: The preliminary effect of the combination surgery for habitual patellar dislocation in adolescents was satisfactory.

Anatomic femoral tunnel position in medial patellofemoral ligament reconstruction: anterior versus posterior.

BACKGROUND: This study aimed to compare the clinical and radiological outcomes of medial patellofemoral ligament reconstruction (MPFLR) between anatomic femoral tunnel positions at anterior and posterior footprints. METHODS: Fifty-seven patients who underwent MPFLR for patellofemoral instability with anterior or posterior femoral tunnels between 2014 and 2021 with at least 2 years of follow-up were retrospectively analyzed. Based on postoperative images, the femoral tunnel positions anterior to the line connecting the adductor tubercle and medial epicondyle were assigned to the anterior group, group A, and those posterior to the line to the posterior group, group P. Thirty-two patients were included in group A (mean age, 22.4 ± 8.8 years), and another 25 patients were included in group P (mean age, 21.1 ± 6.1 years). The International Knee Documentation Committee (IKDC) subjective score, Lysholm score, Tegner activity score, Kujala score, and complications were evaluated. Radiologically, the Caton-Deschamps index (CDI), patellar tilt angle, and patellofemoral osteoarthritis (PFOA) using the Kellgren-Lawrence (KL) scale were evaluated. The patellofemoral cartilage status according to the International Cartilage Repair Society (ICRS) grade, bone contusion, femoral tunnel enlargement, and MPFL graft signal intensity were also evaluated. RESULTS: All clinical scores significantly improved in both groups (p < 0.01). No differences were noted between the two groups in terms of their preoperative demographic data, postoperative clinical scores (IKDC, Lysholm, Tegner, and Kujala), complications, or radiological findings (CDI, patellar tilt angle, PFOA, bone contusion, femoral tunnel enlargement, and graft signal intensity). The ICRS grade for the medial facet of the patella progressed in group A (30%, p = 0.02) but not in group P (18%, p = n.s.). Additionally, no significant differences were observed in the other compartments of the patellofemoral joint. CONCLUSIONS: The clinical outcomes were significantly improved in both groups; however, MPFLR with anterior femoral tunnel position had worse cartilage status on the medial facet of the patella than the posterior femoral tunnel position. LEVEL OF EVIDENCE: Level III.

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

BACKGROUND: In literature, studies evaluating the factors associated the postoperative progression of patellofemoral (PF) osteoarthritis (OA) following patellar stabilization surgery are limited. This study aimed to compare the clinical outcomes after medial patellofemoral ligament reconstruction (MPFLR) as an isolated procedure (iMPFLR) and in combination with anteromedialization (AMZ) of the tibial tubercle osteotomy (TTO) and investigate the factors related to the postoperative progression of PFOA after patellar stabilization surgery. METHODS: Between 2009 and 2020, 30 knees of 23 consecutive patients underwent MPFLR with or without AMZ, using an autologous semitendinosus tendon graft; they were followed up for more than 2 years in the retrospective nature of the study. iMPFLR was performed in cases of recurrent patellar dislocation with normal tibial tubercle-trochlear groove (TT-TG) distance and no PFOA, and MPFLR+AMZ was performed for cases of excessive TT-TG distance, preoperative PFOA of recurrent patellar dislocation, or habitual patellar dislocation. Clinical findings and radiographs of the PF joint were evaluated pre- and postoperatively with PF alignment parameters and PFOA and were compared between surgical procedures. Factors for the postoperative progression of PFOA were compared between the OA progression and non-progression groups. RESULTS: Postoperative clinical score, radiographic parameters except for sulcus angle, TT-TG distance, and progression of PFOA were not significantly different between the iMPFLR and MPFLR+AMZ groups. Postoperative lateral patellar displacement (p = 0.001) and congruence angle (p = 0.017) were significantly different between the OA progression and non-progression groups. CONCLUSION: Similar to MPFLR for recurrent cases, MPFLR with AMZ can improve the clinical and radiographic outcomes in severe cases. The remaining parameters of patellar instability could be affected in the postoperative progression of PFOA after MPFL reconstruction with or without AMZ of TTO for patellar instability.

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

PURPOSE: The purpose of this study was to assess the validity, floor and ceiling effects, and dimensionality of PROMIS Physical Function (PF) and Pain compared to legacy patient reported outcome (PRO) measures in patients undergoing medial patellofemoral ligament (MPFL) reconstruction. METHODS: Patients who underwent MPFL reconstruction between 2018 to 2020 were retrospectively reviewed. Preoperatively, patients completed the IKDC, VR-12, Kujala, SF-12, KOOS JR, PROMIS PF and Pain surveys. Inter-survey convergence was assessed with Spearman correlations. Psychometric analysis included investigations of inter-survey convergent validity, intra-survey floor and ceiling effects, and Rasch analyses with person-item fit and iterative question elimination model fit testing. RESULTS: A total of 76 patients (mean age: 22.6 ± 8.4 years) who completed preoperative surveys were included (compliance: 91.7-96.2%). Preoperatively, age was significantly associated with both PROMIS PF (coefficient: - 0.291, P = 0.005) and Pain scores (coefficient: 0.294, P = 0.002). PROMIS PF had a Very Good correlation with IKDC and PROMIS Pain had a Very Good correlation with KOOS JR. Other correlations ranged from Poor to Good. No significant floor or ceiling effects were observed for any PRO. On iterative question elimination Rasch modelling, only two questions from PROMIS PF remained after 6 rounds of elimination while PROMIS Pain had no questions remaining after 3 rounds of elimination. CONCLUSION: Preoperative PROMIS PF and Pain provided only Fair to Good correlations with most legacy PROs. Although no significant floor and ceiling effects were observed, PROMIS PF and Pain did not perform well psychometrically in this population of patients undergoing MPFL reconstruction. These results suggest PROMIS questionnaires should be used with caution in this population, especially if used in isolation, when discussing clinical expectations with patients. The authors recommend continued use of legacy PROs specific to assessment of patellar instability and function that have established validity in patellar instability populations. LEVEL OF EVIDENCE: Level IV.

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

PURPOSE: The purpose of this study was to investigate the impact of articular cartilage damage on outcomes following medial patellofemoral ligament (MPFL) reconstruction. METHODS: Record review identified 160 patients who underwent isolated MPFL reconstruction at a single institution between 2008 and 2016. Patient demographics, patellofemoral articular cartilage status at surgery, and patient anatomical measures from imaging were obtained via chart review. Patients were contacted and outcomes assessed through collection of Norwich Patellar Instability (NPI) score, Knee injury and Osteoarthritis Outcome Score (KOOS), and Marx activity score as well as an assessment for recurrent patellar dislocation. Outcomes of patients with grade 0-II patellofemoral cartilage damage were compared to those of patients with grade III-IV cartilage damage. RESULTS: One hundred twenty-two patients (76%) with a minimum of one year follow-up were contacted at a mean of 4.8 years post-operatively. A total of 63 patients (52%) had grade III or IV patellofemoral chondral damage at the time of surgery. The majority of the defects was on the medial patella (46 patients-72%) and the mean patellar defect size was 2.8 cm2. Among 93 patients who completed patient-reported outcome scores, the 52 with grade III or IV chondral damage reported a significantly poorer KOOS Quality of Life than the 44 patients with grade 0 to II chondral damage (p = 0.041), controlling for patient age, sex, BMI, and anatomical factors. CONCLUSION: Patients with grade III or IV articular cartilage damage of the patellofemoral joint at the time of MPFL reconstruction demonstrated poorer KOOS knee-related quality of life than patients without grade III or IV articular cartilage damage at a mean of 4.8 years following isolated MPFL reconstruction. LEVEL OF EVIDENCE: Level II.

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.