Morphological Analysis of Hip Joint of Patients Suffering From Recurrent Patella Dislocation.

The purpose was to investigate morphological changes of the hip joint in patients with recurrent dislocation of the patella combined with trochlear dysplasia. There was a retrospective analysis of 148 patients and 150 control subjects. The selection of participants was randomized. Hip and knee data for all participants were obtained from X-ray or computed tomography measurements. Nine values, that is, central edge angle (CEA), acetabulum index angle (AIA), femoral neck-shaft angle, sharp angle, the depth of the acetabulum, femoral anteversion angle (FAA), anterior acetabular section angle (AASA), posterior acetabular section angle (PASA), and sulcus angle, were measured to evaluate differences between the control group and the patient group and analyze the correlation of the sulcus angle in patients to FAA and CEA. Patients with recurrent dislocation of the patella had less acetabular coverage and are more likely to develop developmental dysplasia of the hip than the hips of patients with normal knees. For the patient group, three values, that is, CEA (27.68 ± 5.25 vs. 34.30 ± 3.51 degrees, p < 0.001), AASA (57.14 ± 6.17 vs. 63.08 ± 7.23 degrees, p < 0.001), and PASA (89.53 ± 6.51 vs. 99.63 ± 5.94 degrees, p < 0.001), were decreased. The sharp angle (43.77 ± 3.23 vs. 39.28 ± 3.19 degrees, p < 0.001), AIA (11.52 ± 4.41 vs. 3.73 ± 2.51 degrees, p < 0.001), and FAA (24.68 ± 3.44 vs. 18.49 ± 3.55 degrees, p < 0.001) were increased. The acetabulum became shallower in-depth (7.05 ± 2.18 vs. 10.45 ± 1.61 mm, p < 0.001). There was a weak correlation between the sulcus angle and CEA (r = - 0.302, p < 0.001) and FAA (r = 0.212, p = 0.022). Recurrent patellar dislocation combined with trochlear dysplasia may be associated with the hip morphology. Developmental disorders of the knee joint, and hip joint should be considered in the treatment of patients with recurrent dislocation of the patella.

Cartilage degeneration is associated with activation of the PI3K/AKT signaling pathway in a growing rat experimental model of developmental trochlear dysplasia.

Introduction: Trochlear dysplasia is a commonly encountered lower extremity deformity in humans. However, the molecular mechanism of cartilage degeneration in trochlear dysplasia is unclear thus far. Objectives: The PI3K/AKT signaling pathway is known to be important for regulating the pathophysiology of cartilage degeneration. The aim of this study was to investigate the relationship of the PI3K/AKT signaling pathway with trochlear dysplasia cartilage degeneration. Methods: In total, 120 female Sprague-Dawley rats (4 weeks of age) were randomly separated into control and experimental groups. Distal femurs were isolated from the experimental group at 4, 8, and 12 weeks after surgery; they were isolated from the control group at the same time points. Micro-computed tomography and histological examination were performed to investigate trochlear anatomy and changes in trochlear cartilage. Subsequently, expression patterns of PI3K/AKT, TGFß1, and ADAMTS-4 in cartilage were investigated by immunohistochemistry and quantitative polymerase chain reaction. Results: In the experimental group, the trochlear dysplasia model was successfully established at 8 weeks after surgery. Moreover, cartilage degeneration was observed beginning at 8 weeks after surgery, with higher protein and mRNA expression levels of PI3K/AKT, TGFß1, and ADAMTS-4, relative to the control group. Conclusion: Patellar instability might lead to trochlear dysplasia in growing rats. Moreover, trochlear dysplasia may cause patellofemoral osteoarthritis; cartilage degeneration in trochlear dysplasia might be associated with activation of the PI3K/AKT signaling pathway. These results provide insights regarding the high incidence of osteoarthritis in patients with trochlear dysplasia. However, more research is needed to clarify the underlying mechanisms.

The impact of severity of patellofemoral osteoarthritis on the patient-reported outcomes of total knee arthroplasty with patellar retention: A retrospective comparative study.

OBJECTIVE: The aim of this study was to investigate the impact of preoperative patellofemoral osteoarthritis severity on the final patient-reported outcomes in patients with primary osteoarthritis who underwent total knee arthroplasty with patellar retention. METHODS: In this retrospective study, 167 patients (42 males, 125 females; mean age: 67.9 (range, 50-82) years), who underwent total knee arthroplasty with patellar retention due to primary osteoarthritis were included. The preoperative severity of patellofemoral osteoarthritis was classified according to the Iwano classification system. All the patients were then divided into two groups based on the severity of patellofemoral osteoarthritis: Group I, 73 patients (17 males, 56 females; mean age: 68.4 (range, 50-80) years) with mild osteoarthritis (stage 0-I) and group II, 94 patients (25 males, 69 females; mean age: 67.7 (range, 54-82) years) with moderate to severe osteoarthritis (stage II to IV). The mean follow-up was 42.8 (range, 24-59) months in group I and 41.7 (range, 24-63) months in group II. Clinical outcomes were assessed using the Oxford Knee Score, the New Knee Society Score-function score, and the Kujala score preoperatively and at the final follow-up. Also, the Forgotten Joint Score was performed at the final follow-up. RESULTS: The Oxford Knee Score improved from 22.5 (range, 18-26) preoperatively to 36.5 (range, 30-43) for Group I and from 21.9 (range, 16-25) preoperatively to 35.9 (range, 29-43) for Group II (P < 0.001). The Kujala score increased from 51.2 (range, 45- 65) preoperatively to 79.3 (range, 71-88) for Group I and from 50.3 (range, 42-60) preoperatively to 80.2 (range, 71-86) for Group II (P < 0.001). The New Knee Society Score-function score raised from 60.2 (range, 50-72) preoperatively to 82.2 (range, 72- 90) for Group I and from 59.5 (range, 48-69) preoperatively to 81.4 (range, 73-90) for Group II (P < 0.001). The Forgotten Joint Score was 69.9 (range, 63-76) in Group I and 70.2 (range, 62-77) in Group II (P = 0.49). CONCLUSION: Evidence from this study has shown that the preoperative severity of patellofemoral osteoarthritis has no significant impact on the final patient-reported outcomes of patients with primary osteoarthritis after patellar retention total knee arthroplasty. LEVEL OF EVIDENCE: Level III, Therapeutic Study.

Accuracy of tibial tuberosity-trochlear groove distance and tibial tuberosity-posterior cruciate ligament distance in terms of the severity of trochlear dysplasia.

PURPOSE: Increased tibial tubercle-trochlear groove distance (TT-TG) was proposed as one of the main risk factors for patellofemoral instability (PFI). The increased TT-TG distance indicated externalization of the tibial tubercle with the reference of the trochlear groove. However, in the case of severe trochlear dysplasia, the reference point on the trochlear groove was indistinct, and the accuracy of TT-TG was controversial. The purpose of this study was to evaluate the accuracy of TT-TG and TT-PCL in consideration of the mild and severe trochlear dysplasia. METHODS: From 2015 to 2020, MRI findings of consecutive knee joints with PFI symptoms diagnosed in our hospital were retrospectively analyzed. All knees with trochlear dysplasia were diagnosed by longitudinal MRI scan and lateral radiograph. The knees were classified according to the four-type classification system described by Dejour et al. Twenty cases of type A (mild trochlear dysplasia); 20 cases of type B, C, and D (severe trochlear dysplasia); and 20 cases of normal type were selected and divided into normal group (normal trochlea), mild group (type A), and severe group (type B, type C, type D). Tibial tubercle-trochlear groove distance (TT-TG), tibial tubercle-posterior cruciate ligament distance (TT-PCL), and the Dejour classification of trochlear dysplasia were assessed by 2 experienced orthopedics. The reliability of TT-TG distance and TT-PCL distance was tested by intraclass correlation coefficients (ICCs). RESULTS: Comparing the differences between TT-TG and TT-PCL in the normal, mild, and severe groups, the TT-TG and TT-PCL in the mild and severe groups show different meanings (normal, 8.83 ± 3.62 mm vs. 8.44 ± 4.57 mm, P > 0.05; mild, 17.30 ± 4.81 mm vs. 20.09 ± 5.05 mm, P < 0.05; severe, 10.79 ± 4.24 mm vs. 12.31 ± 5.43 mm, P > 0.05). The Pearson correlation coefficient of TT-TG and TT-PCL measurements of trochlear dysplasia were r = 0.480 (mild group, P = 0.032) and r = 0.585 (severe group, P < 0.001). The intra-observer ICCs of TT-TG were r = 0.814 (mild group) and r = 0.739 (severe group). The inter-observer ICCs of TT-TG were r = 0.810 (mild group) and r = 0.713 (severe group). In the normal knee, the Pearson correlation coefficient of TT-TG and TT-PCL was r = 0.787(P < 0.001), the intra-observer ICC of TT-TG was r = 0.989, and the inter-observer ICC of TT-TG was r = 0.978. CONCLUSION: Compared with the mild trochlear dysplasia, the inter-observer and intra-observer correlations of TT-TG measurements decreased in the group of severe dysplastic trochlea (inter-observer ICC, 0.810 vs. 0.713; intra-observer ICC, 0.814 vs. 0.739). In the present study, the determination of TT-TG and TT-PCL distance are of great significance for patients with low-grade trochlear dysplasia. And TT-PCL, without referring to the abnormal trochlear groove, is an effective indicator to measure the lateralization of tibial tuberosity in patients with severe dysplastic trochlea.

Decreasing Thickness of Partial Lateral Trochlear Cartilage in Patients with Patellar Instability.

OBJECTIVE: To explore morphological characteristics of patellofemoral joint surface of patients with patellar instability by adopting the MRI-based method. METHODS: A retrospective analysis was performed from March 2016 to January 2020 to assess morphological characteristics of the patellofemoral joint surface by Magnetic Resonance Imaging (MRI) scanning knees of 30 patients (24 females, six males) with patellar instability and trochlear dysplasia and knees of 30 subjects from a randomly selected control group (25 females, five males). The control group was matched as per age and sex. All participants had undergone MRI scans in the supine position and keep knees in or near full extension. Six parts were measured in total, including thickness of trochlear cartilage, thickness of patella cartilage, cartilaginous sulcus angle, cartilaginous Wiberg angle, contact range and frequency and distributions of the mean difference measurement of the femoral trochlea, to evaluate the difference of trochlear and patellar morphology between the patient group and the control group. The threshold for statistical significance was set at P < 0.05. RESULTS: There were significant differences in four values between the two groups (P < 0.05). The cartilage thickness two-third along the lateral condyle in the patient group was significantly lower than that in the control group (LCT2,1.80 ± 0.37 vs 2.06 ± 0.52, 1.92 ± 0.36 vs 2.17 ± 0.50), but there was no significant difference in other sites. There was no significant difference in patella thickness between the patient group and the control group. The cartilaginous sulcus angle in the patient group was larger than that in the control group (157.90 ± 6.64 vs 142.23 ± 3.95, P < 0.001), but there was no significant difference in cartilaginous Wiberg angle. The patient group had a larger initial contact ratio (59.47 ± 6.13 vs 46.50 ± 3.67, P < 0.001), and a smaller contact range (16.55 ± 4.14 vs 27.55 ± 4.09, P < 0.001). The deepest part of the intercondylar suclus appears more often in the lateral of the deepest part of the osseous concavity of the femoral trochlea. Among the patient group, 18 cases (60%) were found with the deepest part of the intercondylar suclus lateral to the deepest point of the osseous concavity of the femoral trochlea while among the control group only 4 cases (13.33%) were found. The distribution of trochlear dysplasia of Dejour grades was type B (n = 22), type C (n = 5), and type D (n = 3). CONCLUSION: Thickness of partial lateral trochlear cartilage decreases in patients with patellar instability and the trochlear cartilage develops abnormal morphological characteristics. Moreover, it also suggests that MRI can be used to further present the morphology of cartilage for the convenience of surgical planning.

Clinical outcomes of medial retinaculum plasty versus MPFL reconstruction with concomitant tibial tubercle transfer: a retrospective study.

PURPOSE: To elucidate the clinical outcomes of medial retinaculum plasty versus MPFL reconstruction with concomitant tibial tubercle transfer. METHODS: From January 2014 to July 2018, 57 patients who underwent tibial tubercle transfer combined with medial retinaculum plasty or MPFL reconstruction were enrolled in the present study. The 57 patients were divided into two comparison groups according to the therapeutic protocol. The 25 patients in group I underwent the medial retinaculum plasty and tibial tubercle transfer. The 32 patients in group II underwent the MPFL reconstruction and tibial tubercle transfer. Clinical outcomes were assessed using the knee injury and osteoarthritis outcome score, Kujala score, congruence angle, patellar tilt angle, patellar lateral shift, tibial tuberosity-trochlear groove distance and Caton-Deschamps Index. The clinical outcomes were compared between the two groups preoperatively and at the time of the last follow-up. RESULTS: Significant improvement was seen in both groups postoperatively (P < 0.05). There were no significant differences in the knee injury and osteoarthritis outcome score, Kujala score, congruence angle, patellar tilt angle, patellar lateral shift, tibial tuberosity-trochlear groove distance and Caton-Deschamps Index between the two groups (P > 0.05). CONCLUSION: The combined medial retinaculum plasty and tibial tubercle transfer achieved similar clinical outcomes versus the MPFL reconstruction with concomitant TTT. This therapeutic protocol was a good option in treatment of patellar dislocation with increased TT-TG distance or patella alta.