Trochlear Dysplasia Type Research Articles

Correlation of tibial tuberosity–trochlear groove distance, anterolateral ligament injury, and the type of trochlear dysplasia with the grade of anterior cruciate ligaments tear

BackgroundThe anterior cruciate ligament (ACL) is the most frequently injured ligament. The grade of ACL tear on magnetic resonance imaging (MRI) can help determine the ACL injury treatment. Lateralization of the tibial tubercle is indicated by an increase in the distance of the tibial tuberosity–trochlear groove (TT-TG). Anterolateral ligament (ALL) injury affects a high degree of pivot shift in the knee joint with ACL deficiency. Trochlear dysplasia (TD) is a congenital morphological deformity of the femoral trochlea. An increase in the TT-TG distance, as well as the presence of ALL injuries and TD, can elevate the likelihood of experiencing ACL injuries. This study aims to analyze the correlation of TT-TG distance, ALL injury, and type of TD with the grade of ACL tear through MRI.MethodsThis analytical cross-sectional study was conducted from November 2021 to June 2022 at RSUP Dr. Kariadi Hospital, Semarang. The ACL tear was divided into three degrees. The Schoettle or the Nizić method was used to measure the TT-TG distance. ALL injuries were evaluated by looking at the integrity of the ligament. TD assessment was according to the Dejour classification.ResultsA total of 50 subjects participated in the study. The TT-TG distance for grade I ACL tears was 5.90–14.6 mm (22%), 1.69–18.30 mm (44%) for grade II, and 1.01–14.10 mm (34%) for grade III. The ANOVA test showed no significant relationship between the TT-TG distance and the degree of ACL tear (p = 0.146). ALL injuries were found in six study subjects: One subject (16.7%) had grade I ACL tear, three subjects (50%) had grade II, and two subjects (33.3%) had grade III. The Chi-square test showed no significant correlation between ALL injuries and the degree of ACL tear (p = 0.930). Most subjects did not experience TD (78%), while 20% experienced TD type A and 2% experienced TD type B. In type A TD, 50% of ACL tears were grade I, 30% grade II, and 20% grade III. Among all subjects with TD type B, only one was found to have a grade III ACL tear. Based on the Chi-square test, there was no significant correlation between TD type and the degree of ACL tear (p = 0.110).ConclusionsThere is no significant correlation between the tibial tuberosity–trochlear groove distance, ALL injury, and type of trochlear dysplasia with the grade of ACL tear.

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

ObjectivesTo report outcomes and re-dislocation rates of medial patellar stabilizers reconstruction without bone procedures for correction of anatomical risk factors for patellar instability in skeletally immature patients; to compare isolated medial patellofemoral ligament (MPFL) reconstruction to combined MPFL and medial patellotibial ligament (MPTL) reconstruction in this population. MethodsPatients with open physis and bone abnormalities including patella alta and/or increased tibial tubercle-trochlear groove (TT-TG) distance and/or trochlear dysplasia underwent MPFL reconstruction, either isolated or associated with MPTL reconstruction. Preoperative, 1-year follow-up and the latest follow-up (5 years minimum) data were collected. Radiological and clinical evaluations were conducted, with special attention to failure rate. Comparison of results from isolated MPFL and combined MPFL/MPTL reconstructions was performed. ResultsTwenty-nine patients were included, 19 in the isolated MPFL group (median 14 years old; follow-up 5.8 ​± ​1.7 years) and 10 in the combined MPFL/MPTL group (median 13.5 years old; follow-up 5.2 ​± ​1.4 years). Kujala and Tegner scores increased over time, although without statistically significant differences between the two groups at the latest follow-up (p ​= ​0.840 and p ​> ​0.999, respectively). During follow-up, 5 of 19 (26.3%) isolated MPFL and 2 of 10 (20%) MPFL/MPTL reconstructions experienced recurrence of patellar dislocation (p ​> ​0.999). Trochlear dysplasia type D (p ​= ​0.028), knee rotation (p ​= ​0.009) and lateral patellar tilt angle (p ​= ​0.003) were associated with patellar instability recurrence. The isolated MPFL group showed increased laxity on physical exam at the latest follow-up compared to the 1-year follow-up (patellar glide test (p ​= ​0.002), patellar tilt test (p ​= ​0.042) and subluxation in extension (p ​= ​0.019). This increased laxity was not observed in the MPFL/MPTL group (p ​> ​0.999). Comparing both groups, the glide test was significantly better in the combined MPFL/MPTL group in comparison to the isolated MPFL reconstruction group at the latest follow-up (p ​= ​0.021). ConclusionMPFL reconstruction in isolation or combined with MPTL reconstruction in skeletally immature patients with additional uncorrected anatomical patellofemoral abnormalities leads to acceptable clinical outcomes within a minimum of 5 years follow-up, although has a high failure rate of 24.1%. Addition of a MPTL reconstruction to the MPFL may result in decreased patellar laxity on physical exams, as demonstrated by better patellar glide test, patellar tilt test and subluxation in extension. Level of evidenceLevel III; retrospective cohort study.

The Effect of Patellofemoral Maltracking and Patella Type on Symptomatic Bipartite Patella.

Purpose The aim of this study is to investigate the relationship of trochlear dysplasia (TD) and patella type with bipartite patella (BP). Materials and methods A total of 5,081 knee MRIs taken in our institution were reviewed retrospectively. Patients with a history of knee surgery, previous or recent trauma, and rheumatologic involvement were excluded from the study. The MRIs of 49 patients with bipartite/multipartite patella were detected. Three patients were excluded: two patients had a tripartite variant, and one had multiple osseous dysplastic findings. Overall, 46 patients with BP were included in the study. BPs were classified as type I, II, and III. Patients were divided into symptomatic and asymptomaticgroups according to the presence of edema within the bipartite fragment and adjacent patella. Patients were examined in terms of patella type, trochlear dysplasia, tuberosity-trochlear groove (TT-TG) difference, sulcus angle, and sulcus depth. Results There were 46 patients with BP (28 males and 18 females) (mean age: 33±9.5 years, range: 18-54). Thirty-eight bipartite fragments (82.6%) were type III and eight (17.4%) were type II. There was no type I BP. Seventeen(36.9%) were symptomatic, and 29 (63.1%) were asymptomatic. Seven of the type II (87.5%) and 10 of the type III (26.3%) bipartite fragments were symptomatic. The frequency and degree of trochlear dysplasia (p=0.007 and p=0.041, respectively) were found to be higher in symptomatic patients. The trochlear sulcus angle was higher (p=0.007)and the trochlear depth was lower (p=0.006) in the symptomatic group. No statistically significant difference was found (p=0.247) in terms of TT-TG difference. Type III and type IV patellawere more common in the symptomatic group. Conclusion The current study shows that patellofemoral instability and patella type are associated with symptomatic BP. Patients with trochlear dysplasia, type II BP, and disproportionate patellar facet may have a significantly increased risk of symptomatic BP.

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

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. 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, 12months 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 12months and at last follow-up using several validated scores. Forty-six patients (51 knees) with a mean age of 24.1 ± 7.4years were included in the study. Mean follow-up was 8.9 ± 2.1years. A significant improvement in all clinical scores was observed at 12months 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 1mm 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. 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. IV.

Association of trochlear dysplasia with knee meniscal–cartilage damage and anterior cruciate ligament mucoid degeneration

The purpose of this study was to evaluate meniscal and tibiofemoral cartilage injury in patients with trochlear dysplasia (TD) and investigate whether there were correlations between TD grade and meniscal and cartilage injury. In addition, the relationship between TD and mucoid degeneration of the anterior cruciate ligament (ACL-MD) was investigated. MATERİALS AND METHODS: Magnetic resonance imaging (MRI) examinations of 133 patients with TD were included in the study. TD was graded (types A, B, C, D). The tibial tuberosity (TT)-TG distance was also measured. The ACL was assessed for ACL-MD. Both menisci were evaluated for the degeneration and tears. Medial-lateral tibial plateau (MTP-LTP), medial-lateral femoral condyles (MFC-LFC), and trochlear cartilage were examined for focal cartilage defect (FCD). ACL-MD was present in 42 of the patients with TD (31.6%). There was a significant positive relationship between ACL-MD and TT-TG distance. Meniscal tear was detected in 40 (30.1%) of all patients. FCD were detected in the tibiofemoral compartments in 41 (30.8%) of 133 patients. There was a significant positive relationship between the presence of FCD in the LFC and the type of TD (p<0.01). FCD was present in the LFC of all cases in the type D. A significant positive relationship was found between the TT-TG distance and the presence of FCD, especially in the anterior part of LFC (p<0.01). There was a significant relationship between the lateral trochlear cartilage defect and the type of dysplasia (p=0.037). CONCLUSİON: TD is a significant risk factor for ACL-MD, meniscal, and tibiofemoral cartilage injury.

Tibial Tubercle to Trochlear Groove Distance Measured by Posterior Condylar Reference Line on MRI Can Over-Evaluate Lateralization Deformity of Tibial Tubercle in Patients with Recurrent Patellar Dislocation.

Background: The tibial tubercle to trochlear groove (TT-TG) distance is currently considered as an indication for tibial tubercle osteotomy. While the influence of femoral condylar morphology on such measurement remains unclear. Methods: A total of 86 patients with patellar dislocation (PD) and 86 healthy individuals were enrolled. Femoral condylar morphology and the TT-TG distance measured by anatomical transepicondylar axis (TT-TGa), by surgical transepicondylar axis (TT-TGs), and by posterior condylar reference line (TT-TGp) were assessed by MRI. Unpaired t-test, Spearman, and Pearson correlation analysis were conducted. We determined the pathological value of the parameters and established a binary regression model. Results: The interclass correlation coefficients of all the TT-TG distances were greater than 0.75 in all types of trochlear dysplasia. The lateral/posterior femoral condyle was shorter and the medial/posterior condyle was longer in the study group (28.5 ± 3.3 and 35.2 ± 2.8, respectively) than in the control group (30.9 ± 2.7 and 33.5 ± 2.3, respectively). In the study group, the TT-TGp distance was greater than TT-TGs and TT-TGa distance (p < 0.001). The pathological value of the TT-TG distance was 13.0 mm. Each TT-TG distance revealed a significant OR with regard to PD. Conclusion: The TT-TGa, TT-TGs, and TT-TGp distance can be reliably measured by MRI even in patients with trochlear dysplasia. While the TT-TGp distance may overestimate the lateralization deformity of the tibial tubercle. Posterior femoral condylar dysplasia may be a reason for such overestimating. These findings have not been correlated to clinical outcomes and further studies are required.

The severity of patellar and trochlear dysplasia are correlated.

Patellar instability is a frequent clinical situation in adolescents and young adults. One of the most important risk factors of this condition is trochlea dysplasia. Few studies have analyzed the role of patellar dysplasia. The objective of this paper was to assess the correlation between trochlear and patellar dysplasia. The hypothesis is that patellar dysplasia increased in parallel with femoral trochlear dysplasia. The study included patients operated on at least one knee for patellar instability between 2008 and 2020. For these patients, symptomatic knees (operated or not) were included if they had lateral and patellofemoral skyline radiographs. Two blinded observers categorized each trochlear and patellar dysplasia according to the Dejour and Wiberg classifications. Patellar height was also measured by applying the Caton-Deschamps index. A total of 100 patients were selected, involving 149 symptomatic knees. A significant correlation between trochlear and patellar dysplasia types was found (0.82; p < 0.0001). Dejour types B and C of trochlear dysplasia were significantly more often associated with patellar dysplasia than Dejour type A (p = 0.033 and p = 0.019, respectively). Moreover, severe Wiberg 3 patellar dysplasia was significantly associated with type D Dejour trochlear dysplasia than with the sum of all other Dejour types taken together (p < 0.0001). This study confirms a linear correlation between the severity of patellar and trochlear dysplasia. Further studies are needed to evaluate the place of patellar dysplasia in the therapeutic strategy. Level IV.

Interobserver reliability is higher for assessments with 3D software-generated models than with conventional MRI images in the classification of trochlear dysplasia

PurposeTrochlear dysplasia is a significant risk factor for patellofemoral instability. The severity of trochlear dysplasia is commonly evaluated based on the Dejour classification in axial MRI slices. However, this often leads to heterogeneous assessments. A software to generate MRI-based 3D models of the knee was developed to ensure more standardized visualization of knee structures. The purpose of this study was to assess the intra- and interobserver agreements of 2D axial MRI slices and an MRI-based 3D software generated model in classification of trochlear dysplasia as described by Dejour.MethodsFour investigators independently assessed 38 axial MRI scans for trochlear dysplasia. Analysis was made according to Dejour’s 4 grade classification as well as differentiating between 2 grades: low-grade (types A + B) and high-grade trochlear dysplasia (types C + D). Assessments were repeated following a one-week interval. The inter- and intraobserver agreement was determined using Cohen’s kappa (κ) and Fleiss kappa statistic (κ). In addition, the proportion of observed agreement (po) was calculated for assessment of intraobserver agreement.ResultsThe assessment of the intraobserver reliability with regard to the Dejour-classification showed moderate agreement values both in the 2D (κ = 0.59 ± 0.08 SD) and in the 3D analysis (κ = 0.57 ± 0.08 SD). Considering the 2-grade classification, the 2D (κ = 0.62 ± 0.12 SD) and 3D analysis (κ = 0.61 ± 0.19 SD) each showed good intraobserver matches. The analysis of the interobserver reliability also showed moderate agreement values with differences in the subgroups (2D vs. 3D). The 2D evaluation showed correspondences of κ = 0.48 (Dejour) and κ = 0.46 (high / low). In the assessment based on the 3D models, correspondence values of κ = 0.53 (Dejour) and κ = 0.59 (high / low) were documented.ConclusionOverall, moderate-to-good agreement values were found in all groups. The analysis of the intraobserver reliability showed no relevant differences between 2 and 3D representation, but better agreement values were found in the 2-degree classification. In the analysis of interobserver reliability, better agreement values were found in the 3D compared to the 2D representation. The clinical relevance of this study lies in the superiority of the 3D representation in the assessment of trochlear dysplasia, which is relevant for future analytical procedures as well as surgical planning.Level of evidenceLevel II.

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.

The quantitative influence of current treatment options on patellofemoral stability in patients with trochlear dysplasia and symptomatic patellofemoral instability - a finite element simulation

BackgroundTrochlear dysplasia is highly associated with patellofemoral instability. The goal of conservative and surgical treatment is to stabilize the patella while minimizing adverse effects. However, there is no literature investigating the quantitative influence of different treatment options on patellofemoral stability in knees with trochlear dysplasia. We created and exploited a range of finite element models to address this gap in knowledge. MethodsMRI data of 5 knees with trochlear dysplasia and symptomatic patellofemoral instability were adapted into this previously established model. Vastus medialis obliquus strengthening as well as double-bundle medial patellofemoral ligament reconstruction and the combination of medial patellofemoral ligament reconstruction and trochleoplasty were simulated. The force necessary to dislocate the patella by 10 mm and fully dislocate the patella was calculated in different flexion angles. FindingsOur model predicts a significant increase of patellofemoral stability at the investigated flexion angles (0°-45°) for a dislocation of 10 mm and a full dislocation after medial patellofemoral ligament reconstruction and the combination of medial patellofemoral ligament reconstruction and trochleoplasty compared to trochleodysplastic (P = 0.01) and healthy knees (P = 0.01–0.02). Vastus medialis obliquus strengthening has a negligible effect on patellofemoral stability. InterpretationsThis is the first objective quantitative biomechanical evidence supporting the place of medial patellofemoral ligament reconstruction and medial patellofemoral ligament reconstruction combined with trochleoplasty in patients with symptomatic patellofemoral instability and trochlear dysplasia type B. Vastus medialis obliquus strengthening has a negligible effect on patellar stability at a low total quadriceps load of 175 N.

Why compromise the patella? Five-year follow-up results of medial patellofemoral ligament reconstruction with soft tissue patellar fixation

PurposeThis study investigates the redislocation rate and functional outcome at a minimum follow-up of five years after medial patellofemoral ligament (MPFL) reconstruction with soft tissue patellar fixation for patella instability.MethodsPatients were retrospectively identified and knees were evaluated for trochlea dysplasia according to Dejour, for presence of patella alta and for presence of cartilage lesion at surgery. At a minimum follow-up of five years, information about an incident of redislocation was obtained. Kujala, Lysholm, and Tegner questionnaires as well as range of motion were used to measure functional outcome.ResultsEighty-nine knees were included. Follow-up rate for redislocation was 79.8% and for functional outcome 58.4%. After a mean follow-up of 5.8 years, the redislocation rate was 5.6%. There was significant improvement of the Kujala score (68.8 to 88.2, p = 0.000) and of the Lysholm score (71.3 to 88.4, p = 0.000). Range of motion at follow-up was 149.0° (115–165). 77.5% of the knees had patella alta and 52.9% trochlear dysplasia types B, C, or D. Patellar cartilage legions were present in 54.2%. Redislocations occurred in knees with trochlear dysplasia type C in combination with patella alta.ConclusionMPFL reconstruction with soft tissue patellar fixation leads to significant improvement of knee function and low midterm redislocation rate. Patients with high-grade trochlear dysplasia should be considered for additional osseous correction.

Failure Analysis in Patients With Patellar Redislocation After Primary Isolated Medial Patellofemoral Ligament Reconstruction.

Background:Reconstruction of the medial patellofemoral ligament (MPFL) has become a popular surgical procedure to address patellofemoral instability. As a consequence of the growing number of MPFL reconstructions performed, a higher rate of failures and revision procedures has been seen.Purpose:To perform a failure analysis in patients with patellar redislocation after primary isolated MPFL reconstruction.Study Design:Case series; Level of evidence, 4.Methods:Patients undergoing revision surgery for reinstability after primary isolated MPFL reconstruction were included. Clinical notes were reviewed to collect demographic data, information on the primary surgery, and the mechanism of patellar redislocation (traumatic vs nontraumatic). Preoperative imaging was analyzed regarding femoral tunnel position and the prevalence of anatomic risk factors (ARFs) associated with patellofemoral instability: trochlear dysplasia (types B through D), patella alta (Caton-Deschamps index >1.2, patellotrochlear index <0.28), lateralization of the tibial tuberosity (tibial tuberosity–trochlear groove distance >20 mm, tibial tuberosity–posterior cruciate ligament [TT-PCL] distance >24 mm), valgus malalignment (mechanical valgus axis >5°), and torsional deformity (internal femoral torsion >25°, external tibial torsion >35°). The prevalence of ARF was compared between patients with traumatic and nontraumatic redislocations and between patients with anatomic and nonanatomic femoral tunnel position.Results:A total of 26 patients (69% female) with a mean age of 25 ± 7 years were included. The cause of redislocation was traumatic in 31% and nontraumatic in 69%. Position of the femoral tunnel was considered nonanatomic in 50% of patients. Trochlear dysplasia was the most common ARF with a prevalence of 50%, followed by elevated TT-PCL distance (36%) and valgus malalignment (35%). The median number of ARFs per patient was 3 (range, 0-6), and 65% of patients had 2 or more ARFs. Patients with nontraumatic redislocations showed significantly more ARFs per patient, and the presence of 2 or more ARFs was significantly more common in this group. No significant difference was observed between patients with anatomic versus nonanatomic femoral tunnel position.Conclusion:Multiple anatomic risk factors and femoral tunnel malposition are commonly observed in patients with reinstability after primary MPFL reconstruction. Before revision surgery, a focused clinical examination and adequate imaging including radiographs, magnetic resonance imaging (MRI), standing full-leg radiographs, and torsional measurement with computed tomography or MRI are recommended to assess all relevant anatomic parameters to understand an individual patient’s risk profile. During revision surgery, care must be taken to ensure anatomic placement of the femoral tunnel through use of anatomic and/or radiographic landmarks.

Isolated reconstruction of medial patellofemoral ligament with an elastic femoral fixation leads to excellent clinical results.

The primary objective was to compare the functional outcomes after an isolated MPFL reconstruction using either a quasi-anatomical technique (group A) or an anatomical MPFL reconstruction (group B). The secondary objectives were to compare the rates of redislocation, range-of-motion and subjective patellar instability (Smillie test). A multicenter longitudinal prospective comparative study was performed. Group A had 29 patients and 28 were included in Group B. Patients with trochlear dysplasia types C and D and patients who had undergone a trochleoplasty, a distal realignment or patella distalization concurrently with MPFL reconstruction were excluded. The main evaluation criterion was the Kujala functional score. The mean postoperative Kujala was 90.4 (89.4 in group A and 92.1 in group B). Upon comparing the mean difference between pre- and post-operative values, no differences were detected between the two groups (n.s). Isolated quasi-anatomical MPFL reconstruction using a gracilis tendon autograft for recurrent patellar dislocation provides outcomes as good as the isolated anatomical MPFL reconstruction in patients with no trochlear dysplasia up to those with trochlear dysplasia type A and B at the 2-5years follow-up. Level IV.

Why do MPFL reconstructions fail today?

Aims and Objectives:The medial patellofemoral ligament (MPFL) is the most important passive stabilizer of the patella. In recurrent lateral patellar dislocations reconstruction of the MPFL with an autologous tendon transplant is a frequently performed surgical procedure that shows a low redislocation rate between 1%-7%. However, a complication rate of up to 26% and a reoperation rate of 4% has also been observed. The question, therefore, arises which parameter determines MPFL reconstruction failure. Thus, the purpose of this study was to identify reasons for MPFL reconstruction failure with regard to patients’ complaints leading to reoperation.Materials and Methods:Between July 2015 and May 2019 28 patients (M/F 9/19; mean age 27 ± 8 years) with postoperative complaints after MPFL reconstructive surgery had to undergo revision surgery. Preoperative failure analysis included clinical examination (ROM, ReDPAT, J-sign, and Patella-Glide Test) and radiological imaging with regard to anatomical risk factors of patellar instability and MPFL tunnel positioning. Anatomical predisposition was assessed according to Dejour’s classification of trochlear dysplasia, tibial tuberosity-trochlear groove distance, tibial tuberosity-posterior cruciate ligament distance, patellar height, varus/valgus malalignment and torsional profile.Results:Three major reasons for revision surgery were identified: (1) patellar redislocation, (2) limited range of motion (ROM), and (3) anterior knee pain (AKP). Sixteen of the 28 patients (57%) suffered from recurrent patellar dislocation. Severe trochlear dysplasia (type B/D according to Dejour) (44%), valgus deformity (19%), increased patellar height (19%), and misplaced femoral drill channels (31%) could be identified as risk factors for redislocation. An increased TT-TG (>20mm) or TT-PCL (>24mm) distance could not be observed in any patient in this group. Limited ROM with an average maximum flexion ability of about 92 ± 26° was observed in 10 of the 28 patients (36%), of which 9 patients additionally complained of AKP. Misplaced femoral drill channels (80%), severe trochlear dysplasia (type B/D according to Dejour) (20%) and postoperative decreased patellar height (20%) could be identified as risk factors for postoperative limited ROM. Other reasons for postoperative AKP were increased femoral antetorsion (n=1) and retropatellar cartilage damage (n=2) without any loss of ROM.Conclusion:Recurrent dislocation of the patella, limited ROM and AKP were identified as most common complications after MPFL reconstruction leading to revision surgery. Failures are mainly due to neglected bony risk factors of patellar instability (trochlear dysplasia, patella alta and valgus deformity) and to misplaced femoral drill channels. Appropriate patient selection and an accurate surgical technique appear mandatory for a good clinical outcome when patellar instability is treated solely with an MPFL reconstruction.

Classification of dysplasia of the femoral trochlea in patients with patellar instability depends on the evaluation plane

ObjectiveTrochlear dysplasia is a major predisposing factor of patellar instability (PI). Dysplasia types are generally evaluated using the Dejour classification, but it is unclear whether this classification covers the entire spectrum. The objective of this study was to confirm whether the trochlear types on an axial view categorised according to the classification represent the entire trochlear shape.MethodsNinety knees from 81 patients with PI and 15 knees from 10 healthy volunteers (HVs) were evaluated. Three-dimensional knee models were created by MRIs. The femoral trochlear planes (FTPs) were defined as virtual cross sections including the transepicondylar axis, closer to the perpendicular plane of the articular surface. FTP 0 was defined as the reference plane including the proximal edge of the femoral trochlea and FTP θ as the plane making optional angle θ to FTP 0. Trochlear dysplasia types according to the classification were evaluated at every 10 degrees of FTPs up to 60 degrees (FTP 10, 20, 30, 40, 50 and 60). A trochlea with a sulcus angle <145° was defined as normal. Changes in the trochlear type according to FTPs, and agreement with clinical classification were evaluated.ResultsEighty-six knees (96%) in patients with PI and 12 (80%) in HVs showed changing trochlear types in different FTPs. Patterns of change varied among patients with PI and HVs. This suggests morphological variation of dysplastic trochleae. Agreement of trochlear type on each FTP with the clinically used Dejour classification was 42% on FTP 10, 49% on FTP 20, 33% on FTP 30, 22% on FTP 40, 22% on FTP 50% and 22% on FTP 60 in patients with PI, and 20% at FTP 10, 80% at FTP 20 and 100% on FTP 30 through FTP 60 in HVs. This suggests that the trochlear types in the clinically used plane do not always match the ones on the planes describing the contact surface to the patella.ConclusionThe trochlear types on an axial view provided by the Dejour classification do not represent the entire trochlear geometry. Multiple axial planes should be clinically used to more precisely describe the entire trochlear shape.

Trochleoplasty: Groove-Deepening and Entrance Grooveplasty

Trochleoplasty is a safe and effective surgical technique for addressing certain types of trochlear dysplasia in the setting of patellar instability. This article discusses groove-deepening trochleoplasty and entrance grooveplasty, including indications, associated procedures, outcomes, and complications.

Fluoroscopic guided tunnel placement during medial patellofemoral ligament reconstruction is not accurate in patients with severe trochlear dysplasia.

Accurate femoral tunnel placement is of great importance during medial patellofemoral ligament (MPFL) reconstruction. Purpose of the present study was to investigate the influence of trochlear dysplasia on the accuracy of fluoroscopic guided femoral tunnel placement. CT-Scans of 30 knees (five with regular shaped trochlea, 10 with a Type A and five each with a Type B, C, or D trochlear dysplasia) were imported into the image analysis platform MeVisLab. A 3D Bone Volume Rendering (VR) and a virtual lateral radiograph was created. The anatomic femoral MPFL insertion was identified on the 3D VR. On virtual lateral radiographs, the MPFL insertion was identified based on landmarks described by Schöttle et al. using three different perspectives: Best possible overlap of the femoral condyles (BC) and a tangent along posterior border of the posterior femoral cortex (pBC); a tangent along the anterior border of the posterior cortex (aBC); and best possible overlap of the distal part of the posterior femoral cortex (BF). Distances between the anatomic attachment and radiographically obtained insertions were measured on the 3D VR and compared according to the type of trochlear dysplasia. Significantly lower accuracy of fluoroscopy guided tunnel placement in MPFL reconstruction was found in knees with Type C and D dysplasia. This effect was observed irrespectively from the radiologic perspective (pBC, aBC, and FC). In the pBC view (highest accuracy), the mean distance from the centre of the anatomic MPFL attachment to the radiographically defined location was 4.3mm in knees without trochlear dysplasia and increased to 4.8mm in knees with Type A dysplasia, 3.8mm in knees with Type B dysplasia, 6.7mm (p < 0.001) in knees with Type C dysplasia, and 7.3mm (p < 0.001) in knees with Type D dysplasia. Radiographic landmark-based femoral tunnel placement in the pBC view provides highest accuracy in knees with a normal shaped trochlea or low grade trochlear dysplasia. In patients with severe dysplasia, fluoroscopy guided tunnel placement has a low accuracy, exceeding a critical threshold of 5mm distance to the anatomic MPFL insertion irrespective of the radiographic perspective. In these patients, utilization of anatomic landmarks may be beneficial. IV.

Recurrent patellar dislocations: trochleoplasty improves the results of medial patellofemoral ligament surgery only in severe trochlear dysplasia.

Medial patellofemoral ligament (MPFL) surgery combined with trochleoplasty (TP), is often performed to restore the normal patellofemoral biomechanics avoiding recurrent lateral patellar dislocation (LPD) in patients with trochlear dysplasia (TD). However, it is still unclear whether combining TP and MPFL surgery would be more beneficial than performing MPFL surgery on its own. This meta-analysis quantitatively synthesizes and compares published data on the outcomes of recurrent LPD treatment using MPFL surgery without or with TP in patients affected by TD. A systematic literature search about the treatment of recurrent LPD in the presence of TD was conducted. The primary outcome was redislocation rate, analyzed for different types of TD. Kujala, and IKDC scores, as well as complication rate, were also analyzed through a separate meta-analysis. No statistically significant difference was found in the overall redislocation rate of MPFL surgery without and with TP. There was, however, a statistically significant difference (p < 0.001) in redislocation rate after MPFL surgery without TP between patients with type A or B TD (2.7%) and in patients with type C or D TD (18.6%). In the analysis for every single type of TD, the following results were obtained: redislocation rate of 1.8% in type A, 3.2% in type B, 11.9% in type C, and 7.4% in type D. A statistically significant difference in the complication rate, favouring MPFL surgery without TP, was documented. Both surgical approaches provided a significant improvement with no difference in Kujala and IKDC scores. These results were confirmed when data were analyzed including only patients with type B, C, or D TD, or without additional bone remodelling procedures. Isolated MPFL is as effective as combined TP and MPFL surgery in preventing redislocation and improving clinical and functional outcomes in patients with recurrent LPD and knees affected by moderate TD. However, in case of severe TD, the redislocation rate is lower when TP is performed in combination with MPFL surgery, although with comparable clinical outcomes and a higher risk of post-operative range of motion (ROM) limitation. Systematic review and meta-analysis, Level IV.

ARE THERE SIDE-TO-SIDE DIFFERENCES IN KNEE MORPHOLOGY IN PATIENTS WITH BILATERAL PATELLAR INSTABILITY

Introduction It is not known if there are side-to-side differences in knee morphology in patients with bilateral patellar instability (BPI). Such knowledge would help to answer the question whether similar treatment and prognosis could be expected for both knees in patients with BPI. The purpose of our study was to evaluate and compare anatomic / morphologic risk factors between knees in patients with BPI. Materials and Methods Of 294 patients who underwent surgical stabilization for patellar instability (2008-2017), 32 patients were identified who underwent staged or simultaneous bilateral surgery. This formed the study cohort. Demographic data, mechanism of initial injury and first knee side to be symptomatic were recorded. Radiographs and MRI of these 64 knees were evaluated for trochlear dysplasia (trochlear depth), patellar height (Caton-Deschamps index, Insall-Salvati ratio), patellar tilt, TT-TG distance, sulcus angle (cartilaginous and bony) and trochlear bump (cartilaginous and bony). The number and percentage of knees with pathologic values for measured risk factors were analyzed. For each risk factor, 15% side-to-side differences were considered significant. Statistical correlation was calculated between the time of presentation (first symptomatic knee) and magnitude of risk factors. All measurements were repeated after a 3-week interval and ICC was calculated to determine intraobserver reliability. Results The mean age of 32 patients was 14.6 years. 17/32 patients were females. 29 patients had staged surgery with mean interval of 21 months between surgeries; 3 patients had simultaneous surgery on each knee. Patients with BPI had multiple risk factors. 22/32 patients (69%) had the same Dejour type of trochlear dysplasia. For each measured risk factor, the number and percentage of patients with 15% or more side-to-side differences is shown (Table 1). There were significant side-to-side differences in patellar height ratios, TT-TG distance, and trochlear bump. The timing of presentation did not correlate with increased risk factors, i.e, the knee that presented earlier did not have increased risk factors compared to contralateral knee. ICC showed excellent intraobserver reliability. Conclusion There were significant side-to-side differences between knees in patients with BPI. Treatment and prognosis should be based on anatomic risk factors for each knee in patients with BPI. [Table: see text]

Early outcomes of an anatomic trochlear-cutting patellofemoral arthroplasty: patient selection is key.

The purpose of this study was to report outcomes of a recent anatomic trochlear-cutting patellofemoral arthroplasty (PFA) system at > 3years. The hypothesis was that its functional scores and revision rates would be at least equivalent to those reported for other 'trochlear-cutting' implants in the literature. Twenty-eight consecutive patients that had received PFA using the same anatomic trochlear-cutting implant (KneeTech PFJ, Corin-Tornier, Montbonnot, France) with a dome-shaped patellar button and had systematic lateral facetectomy without lateral release were enrolled. Radiographic parameters collected pre-operatively included: trochlear dysplasia type and patellar height, TT-TG, patellar tilt and shape. Clinical scores collected pre-operatively and at > 3years included: Oxford Knee Score (OKS) and Knee Society Score (KSS). The initial cohort comprised 23 women (82%) and five men (18%), aged 63.3 ± 14.7years, of which 23 had trochlear dysplasia (82%). One patient (4%) could not be reached, and three (11%) were revised to TKA due to arthritic progression, aged 77, 80 and 83years at index operation, only one of which had trochlear dysplasia (type A). At final follow-up, none of the remaining 24 patients had complications; their OKS was 35.0 ± 10.3 and KSS symptoms and function were 19.8 ± 5.0 and 71.7 ± 13.6. The anatomic trochlear-cutting PFA granted satisfactory scores and prevented mechanical complications, but the high incidence of early revisions, all due to spread of arthritis hence to improper patient selection. PFA should be restricted to patients with trochlear dysplasia, in whom arthritis was triggered by patellar instability and maltracking rather than degenerative or age-related diseases. Retrospective case series, Level IV.