Objectives To report the clinical outcomes of combined femoral derotation osteotomy and medial retinaculum plasty for recurrent patellar dislocation in patients with excessive femoral anteversion. Methods From January 2015 to March 2018, 20 knees in 20 patients (18 female, 2 male) with a mean age of 21 ± 4.2 years (range, 16 to 28 years) were retrospectively reviewed. All patients had undergone femoral derotation osteotomy and medial retinaculum plasty for recurrent patellar dislocation and excessive femoral anteversion angle (FAA > 25°). CT and X‐rays were used to assess the correction of the femoral anteversion angle, the tibia tuberosity‐trochlear groove (TT‐TG) distance, patellar tilt, and the congruence angle following the combinatory operations. Subjective scores, such as Kujala, International Knee Documentation Committee (IKDC), Tegner, and visual analogue scale (VAS) scores, were used to evaluate knee function preoperatively and postoperatively. Results No recurrence of patellar dislocation occurred in these patients during an average of 18 months (range, 12 to 23 months) of follow‐up. The mean of the FAA was corrected to 15.80° ± 3.58° postoperatively compared with 31.42° ± 4.95° preoperatively ( P < 0.001). The TT‐TG distance was decreased from 22.17 ± 5.28 mm before surgery to 19.42 ± 4.57 mm after surgery ( P = 0.03). The patellar tilt and congruence angle were improved from 30.43° ± 5.30°, 43.30° ± 11.04° to 15.80° ± 3.94°, 16.64° ± 9.98°, respectively ( P < 0.001). The Kujala score was improved from 72.4 ± 19.90 before the surgery to 88.2 ± 12.25 after the surgery ( P < 0.001). The IKDC score was improved from 70.56 ± 21.44 to 90.78 ± 14.32, and the VAS score was decreased from 4.23 ± 2.11 preoperatively to 1.27 ± 1.08 postoperatively ( P < 0.001). No significant difference in Tegner score (5.46 ± 2.49 vs 5.79 ± 1.44) was found before and after the surgery ( P = 0.2). Patients younger than 20 years old had lower Kujala (83.46 ± 14.56 vs . 90.84 ± 7.74, P = 0.02) and IKDC (83.49 ± 17.35 vs 92.46 ± 9.28, P = 0.04) scores than those older than 20 years. Conclusion Good knee function, pain relief, and improved patellofemoral congruence were achieved with the combined femoral derotation osteotomy and medial retinaculum plasty. The combined operations serve as an ideal treatment for recurrent patellar dislocation and address the primary risk factors.

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Background Developmental factors were assumed to be the key factors that influenced the morphology of femoral trochlea. This study investigated the effects of insufficient patellar stress after birth on the morphological development of the femoral trochlea. Effects of insufficient patellar stress on femoral trochlea were investigated using surgical induced patellectomy and patellar dislocation in growing rat model. Methods In this study, two experimental groups and one sham group (SG) were established. Thirty-six Wistar rats (female, 28 days of age) were randomly assigned to three groups. The patellectomy group (PG), rats underwent the patellectomy in this group. The dislocation group (DG), rats underwent the surgery-induced patellar dislocation. Histological staining (Safranin-O and fast green), Micro-computed tomographic (Micro-CT) analysis in two experimental endpoints (3, 12 weeks postoperatively) were selected to evaluate morphological changes of the femoral trochlea. Results Articular cartilage on the trochlear sulcus was remodeled at 3 weeks after the surgery, and degenerated at 12 weeks through the histological staining. The femoral trochlear angle (FTA) did not show a significant difference at 3 week between the experimental groups and the sham group (PG vs SG P = 0.38, DG vs SG p = 0.05), but the FTA was significantly increased in experimental groups at 12 weeks(PG vs SG P = 0.001, DG vs SG p = 0.005). The Bone volume density (BV/TV), Trabecular number (Tb.N) under the trochlea groove were significantly reduced at 3 weeks postoperatively in the experimental groups (PG vs SG p = 0.001, DG vs SG p = 0.002). No significant difference was found in BV/TV and Tb. N among the three groups at 12 weeks postoperatively. Conclusion Surgical induced patellectomy and patellar dislocation leads to the dysplastic trochlear sulcus in growing rats. Besides the bone morphology of trochlear sulcus, the articular cartilage and subchondral trabecula under the trochlear sulcus were remodeled early stage after the surgery.

Purpose: The aim of this study was to perform a meta-analysis to compare the effects of repair of medial patellofemoral ligament (MPFL) and conservative treatment in patients with acute primary patellar dislocation (PPD). Method: The databases we used to search the studies included MEDILINE, EMBASE, and Cochrane registry of controlled clinical trials. Five randomized controlled studies comparing the effects of MPFL repair versus conservative treatment with 300 acute PPD patients were included in the present meta-analysis. Primary outcome was redislocation rate and secondary outcomes included Kujala score, percentage of excellent or good subjective opinion, Tegner activity score, and knee injury and osteoarthritis outcome score (KOOS; pain, symptoms, and activities of daily living). Results: The outcome of the Kujala score was statistically significant between the two treatments and indicated that MPFL repair had a higher Kujala score than conservative treatment in patients with acute PPD. There was no significant difference between the two treatments regarding the redislocation rate ( p = 0.32), percentage of excellent or good subjective opinion ( p = 0.15), Tegner activity score ( p = 0.24), and KOOS ( p > 0.05). Conclusions: Based on the available data, MPFL repair did not reduce the risk of redislocation nor did it produce any significantly better outcome based on the clinical manifestations, including anterior knee pain and knee activities. Only the Kujala score was improved by MPFL repair compared with conservative treatment.

Purpose The purpose of this meta-analysis was to compare the efficacy and imaging parameters of kinematic alignment (KA) and mechanical alignment (MA) in total knee arthroplasty (TKA) and to evaluate whether patients undergoing KA-TKA benefited more than those undergoing MA-TKA. Methods Studies comparing the efficacy of KA-TKA and MA-TKA were included after searching and screening in the database, including PubMed, Embase, Web of Science and Cochrane Database Library. A total of 1420 patients were enrolled in the study, with 736 MA-TKA and 738 KA-TKA. The primary outcomes were postoperative knee function scores including KSS series, WOMAC, KOOS and OKS. Secondary outcomes included the operative time, the length of hospital stay, knee extension/flexion angle, and some imaging parameters. The risk of bias for included studies was assessed using the Cochrane Collaborative risk-of-bias assessment tool or the Newcastle-Ottawa Scale(NOS). Results Sixteen studies were included in this meta-analysis (11 randomized controlled studies and 5 cohort studies). Primary outcomes: Knee Society score (KSS, MD = 8.36, 95% Cl: 0.83–15.90) and combined KSS (MD = 15.24, 95% CI: 5.41–25.07) were higher in KA-TKA than in MA-TKA, and other functional scores were not statistically significant in KA-TKA and MA-TKA, including knee injury and osteoarthritis outcome score (KOOS), Oxford knee score (OKS), Knee Function score (KFS) and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). Secondary outcomes: KA-TKA resulted in smaller medial proximal tibial angle (MPTA) and lateral distal femoral angle (LDFA) compared to MA-TKA. For other outcome measures, KA-TKA showed similar results compared to MA-TKA, including hip-knee-ankle (HKA) angle, extension/flexion angle, tibial component slope angle, joint line orientation angle (JLOA), the operation time, the length of hospital stay and ligament release rate. Conclusions In our analysis results, patients undergoing KA-TKA benefit as much as patients undergoing MA-TKA. KA may be a viable reference in total knee replacement.