Prospective case series, Level IV.

Purpose Increased femoral antetorsion influences patellofemoral joint kinematics. The aim of this study was to retrospectively evaluate the clinical outcome after derotational osteotomies and combined procedures in patients with patellofemoral instability. Methods All patients with derotational osteotomies and combined procedures in patients with patellofemoral instability and increased femoral antetorsion performed between 2007 and 2016 were retrospectively analyzed. Exclusion criteria were open growth plates, posttraumatic deformities, and a follow‐up period less than 12 months. Simple radiography and magnetic resonance imaging to evaluate cartilage lesions, trochlear dysplasia, tubercle distance, and osseous malalignment as frontal axis and torsion were performed on every patient. Patients were evaluated pre‐ and postoperatively using the visual analog scale (VAS) for pain, the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score, the subjective IKDC evaluation form, the Lysholm score, and the Tegner activity score. Results Out of 222 femoral osteotomies, a total of 42 patients (44 knees) met the inclusion criteria. Mean preoperative femoral antetorsion of 31° (SD ± 9°) and mean valgus malalignment of 1° (SD ± 3°) were observed. An intended derotation of 12° (SD ± 5°) was set overall. The additional procedures included correction of valgus in 50% (n = 22), MPFL reconstruction in 64% (n = 28), patellofemoral arthroplasty in 18% (n = 8), trochleoplasty in 14% (n = 6), tibial tubercle transfer in 14% (n = 6). During the mean follow‐up period of 44 months (SD ± 27, range 12–88), a total of five patients were lost to follow‐up, resulting in a follow‐up rate of 89% (n = 39). A significant pain relief from VAS 4 (SD ± 3) to VAS 2 (SD ± 2) (p = 0.006) as well as improved scores, WOMAC: from 80 (SD ± 14) to 88 (SD ± 16) (p = 0.007), Lysholm: from 46 (SD ± 21) to 71 (SD ± 24) (p < 0.001), IKDC: from 54 (SD ± 13) to 65 (SD ± 17) (p < 0.001), were observed postoperatively. During the follow‐up period, no patellar re‐dislocation was observed. Conclusion Combined derotational osteotomy is a suitable treatment for patellar instability due to torsional malformity, as it leads to a significant reduction of pain, and a significant increase of knee function with good‐to‐ excellent results in the short‐term follow‐up. Level of evidence IV.

Prospective case series, Level III.

III.

The present paper introduces an individualized approach to adopt the degree of valgus correction in dependence of the underlying pathology. The area of interest on the tibial plateau lies in between the 50% and 65% coordinate on the tibial plateau, or in between a mean mFTA of 0.3° and 3.4° of valgus, respectively. Differences of the resulting mFTA between each area are small, and therefore a precise surgical technique is mandatory.

III.

Prospective case series, Level III.

Purpose To prospectively evaluate the clinical and radiographic outcomes and survivorship at 2 and 5 years after isolated contemporary patellofemoral inlay arthroplasty. Methods Thirty‐four patients were prospectively enrolled in the study and were evaluated preoperatively and at 2 and 5 years postoperatively. Clinical outcomes included the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score and the visual analogue scale (VAS) for pain. Kellgren‐Lawrence grading was used to assess the progression of tibiofemoral osteoarthritis and the Caton‐Deschamps Index to determine patellar height. A Kaplan–Meier survival analysis was used to investigate the implant survivorship. Preoperative patient characteristics were compared among failures and success to determine potential risk factors and patient satisfaction was rated postoperatively. Results Five of the 34 patients were lost to follow‐up resulting in a final follow‐up rate of 86%. The total WOMAC subscores of pain and function and the VAS Pain improved significantly at 2‐ and 5‐years, with no significant difference between the two time points. The WOMAC stiffness subscale reached significant improvement at 2‐year follow‐up alone. No significant progressions of tibiofemoral arthritis or changes in patellar height were observed. A total of six patients (17.1%) failed leaving a survival rate of 91% after 2 years and 83% after 5 years. The main cause for postoperative failure was persistent knee pain; however, no significant preoperative risk factor in patient characteristics could be identified. Conclusion Patellofemoral inlay arthroplasty shows high patient satisfaction with significant improvement in knee function and pain relief after mid‐term follow‐up with no radiographic progression of tibiofemoral OA. Level of evidence Prospective case series, Level III.