Chronic fixed-permanent lateral patellar dislocation can be successfully corrected in skeletally mature patients, with satisfactory midterm outcomes.

Abstract

Background: Chronic permenant lateral patellar dislocation is a rare, complex condition that affects an adult's entire lower extremity and may cause functional impairment. This study aimed to identify single-stage surgery for functional recovery in patients and to assess the radiological and functional outcomes of our technique, particularly concerning patellofemoral osteoarthrosis, at mid-term follow-up.

Methods: The study retrospectively analyzed eight patients with eleven afflicted knees who had our novel surgical method, termed the all-in-one treatment, from 2011 to 2017. The average follow-up duration was 11.3 years, with a range of 6 to 12 years. An analysis was conducted on the files of patients who satisfied the specified criteria. Data, comprising questionnaires, clinical examinations, radiographs, and functional assessments, were recorded. All patients underwent assessments of the lateral patellofemoral angle, compliance angle, Iwano classification, sulcus angle, and Wiberg-Patellar type. We classified all patients according to the Outerbridge chondromalacia classification, and conducted additional clinical assessment using the Kujala et al. patellofemoral impairment score.

Results: All patients experienced functional improvement, with a mean preoperative Kujala score of 40.89 and a mean postoperative Kujala score of 68.3. No instances of bone nonunion, skin necrosis, or periprostatic fractures were identified in our investigation. No significant degenerative alterations were observed on tomography throughout follow-up, except in one patient who had undergone trochleoplasty. During the postoperative period, no patient experienced any instability.

Conclusion: Our study's primary finding is that the functional gain of knees with chronic dislocations, on which we performed our surgical approach, demonstrated a significant long-term improvement. However, further research is needed to compare single-stage and multi-stage treatments and to assess the long-term outcomes of these treatments and the associated risk of patellafemoral osteoarthritis, re-dislocation, and loss of functional gain.