Purpose The purpose of this study was to evaluate the clinical outcomes of medial patellofemoral ligament (MPFL) reconstruction combined with derotational distal femur osteotomy in patients with recurrent patellar dislocation who had excessive femoral anteversion angle and trochlear dysplasia. Methods Between 2015 and 2020, 64 patients (64 knees) with recurrent patellar dislocation, who had excessive femoral anteversion angle (≥ 25°) and trochlear dysplasia and were surgically treated using derotational distal femur osteotomy and MPFL reconstruction, were eligible for this retrospective study. These patients were assigned to two groups according to the grade of trochlear dysplasia. Group A (type A trochlear dysplasia, n = 33) and Group B (type B, C, D trochlear dysplasia, n = 31). Preoperative and postoperative patellar tilt angle (PTA), Caton–Deschamps index (CD‐I), tibial tubercle–trochlear groove (TT–TG) distance and femoral anteversion angle were evaluated. Patient outcomes were assessed using the preoperative and postoperative International Knee Documentation Committee (IKDC) score, Kujala score, Lysholm score, Tegner score, and visual analog scale (VAS) score. Results A total of 64 patients (64 knees) were evaluated in this study, with a mean follow‐up period of 28.4 ± 3.6 months. There were no cases of wound infection, osteotomy site fractures, deep venous thrombosis of the lower extremities, or re‐dislocation in the two groups during the postoperative follow‐up period. All patients returned to full extension and flexion. The postoperative Tegner score, Lysholm score, Kujala score, IKDC score, VAS score, PTA, CD‐I, TT–TG distance, and femoral anteversion angle were significantly improved compared with the preoperative status (P < 0.05). There was no significant difference between the two groups (n.s.). Conclusion MPFL reconstruction combined with derotational distal femur osteotomy showed satisfactory clinical outcomes during follow‐up in patients with recurrent patellar dislocation who had excessive femoral anteversion angle and trochlear dysplasia. Even patients with high‐grade trochlear dysplasia showed satisfactory results. For those patients, additional surgery is not necessary. Level of evidence Level III.

Background The aim of this study is to determine whether distalization of the tibial tubercle is necessary for patients with recurrent patellar dislocation accompanied by patella alta and increased TT-TG. Methods In this retrospective study, all 70 patients (70 knees) with recurrent patellar dislocation accompanied by TT–TG distance ≥20 mm and patella alta (CD-I ≥ 1.4) were surgically treated using MPFLR combined with medialization of the tibial tubercle or medialization and distalization of the tibial tubercle in the Third Hospital of Hebei Medical University between 2017 and 2019. 33 patients(33 knees) received MPFLR combined with medialization of the tibial tubercle (MPFLR + TTm group), 37 patients(37 knees) received MPFLR combined with medialization and distalization of the tibial tubercle (MPFLR + TTm-d group). Evaluation indicators included knee injury and osteoarthritis prognostic score (KOOS) and Kujala score evaluation, congruence angle (CA), patellar tilt angle (PTA), TT-TG distance, Blackburne-Peel index (BP-I), Caton-Deschamps index (CD-I). Results A total of 70 knees (70 patients) with a mean follow-up time of 32 ± 6 months were evaluated in the present study. The postoperative, the PTA, CA, CD-I, BP-I, and TT-TG distance significantly improved in the two groups (P < 0.05), and there was no statistical difference between the two groups (>0.05). The KOOS and Kujala scores of the two groups at the last follow-up were significantly higher than the preoperative scores (P < 0.05), and there was no statistical difference between the two groups (P>0.05). No complications were noted in either group. Conclusion For patients with recurrent patellar dislocation accompanied by increased TT-TG distance and patella alta, distalization is not needed and medialization is sufficient even in the presence of patella alta.

Background Proper lower limb alignment and soft tissue balance are significant indicators to measure the success of total knee arthroplasty (TKA). Previous studies have confirmed that soft tissue relaxation around the knee after TKA will change over time; however, the relationship between lower limb alignment and soft tissue balance after TKA is still unclear. We studied (1) whether the change of soft tissue balance around the knee with time after PS TKA would affect the alignment of the lower limbs; (2) Whether the accuracy of lower limb alignment during PS TKA affects postoperative soft tissue remodeling. Methods In this study, 100 patients were recruited after PS TKA. Among them, 50 patients with a hip knee ankle (HKA) angle of ≤ ± 3 ° were set as the neutral group, and 50 patients with HKA angle of ＞± 3 ° were set as the deviation group. The imaging results measured the hip knee ankle (HKA) angle before the operation as well as the HKA, varus, and valgus angles at 1, 3, 6, 12, and 24 months after TKA. Clinical assessment included range of motion (ROM), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and Knee Society Score (KSS). Results Eight people were excluded in the experiment. The study enrolled 47 patients in the neutral group and 45 patients in the deviant group follow up for 2 years . During the follow-up, the HKA angles were 1.64 °, 1.66 °, 1.69 °, 1.67 °, and 1.64 ° in the neutral group and 4.35 °, 4.38 °, 4.40 °, 4.42 °, and 4.42 ° in the deviation group. There was no statistical significance in the changes of HKA angle in the follow-up of the two groups (P > 0.05). The mean varus angles of the patients in the neutral group were 5.77 °, 4.17 °, 4.06 °, 4.06 °, and 4.09 °, while the mean varus angles of the patients in the deviation group were 5.68 °, 4.20 °, 4.18 °, 4.09 ° and 4.05 °, with no significant difference between the groups (P > 0.05). The mean valgus angles of the patients in the neutral group and deviation group were 2.47 ° and 2.45 ° (P = 0.841), 3.45 ° and 2.88 ° (P < 0.001), 3.63 ° and 3.07 ° (P < 0.001), 3.60 ° and 3.06 ° (P < 0.001), 3.63 ° and 3.10 ° (P < 0.001). ROM, WOMAC and KSS of the two groups were significantly improved after operation, and there was no difference between the two groups. Conclusion This study shows that whether the alignment is accurate or not in the early stage after TKA, the relaxation of the medial and lateral soft tissues of the knee joint change; however, this change will not significantly affect the alignment of the lower limbs. Postoperative residual varus deformity will limit medial soft tissue remodeling. Level of evidence III.