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. 2021 Jan 28;9(1):2325967120981636.
doi: 10.1177/2325967120981636. eCollection 2021 Jan.

Patellofemoral Dislocation Recurrence After a First Episode: A Case-Control Study

Juan Pablo Martinez-Cano  1   2 , Julián Chica  1 , Juan José Martinez-Arboleda  2 , Erika Rincón-Escobar  2 , Laura Zamudio-Castilla  1 , Martin Renjifo  1 , Alfredo Martinez-Rondanelli  1   2
Affiliations

Patellofemoral Dislocation Recurrence After a First Episode: A Case-Control Study

Juan Pablo Martinez-Cano et al. Orthop J Sports Med. .

Abstract

Background: Lateral patellar dislocation can become a recurrent problem after the first episode. Identifying those patients who are at increased risk of redislocation is important for the treatment decision-making process.

Purpose: To identify clinical and radiologic risk factors for recurrence of patellar dislocation after a first episode.

Study design: Case-control study; Level of evidence, 3.

Methods: The study included patients with lateral patellar dislocation and a 1-year minimum follow-up who were seen between 2011 and 2018. Patients aged 10 to 65 years were included. Patient characteristics, physical examination (patellar apprehension, J sign), and radiographs were reviewed. The Caton-Deschamps and Insall-Salvati ratios were used to evaluate patella alta. High-grade trochlear dysplasia was defined as Dejour types B, C, and D.

Results: A total of 130 patients (139 knees) with primary lateral patellar dislocation were included. Recurrent dislocation was seen in 83 knees (59.71%). Stepwise logistic regression analysis demonstrated that Caton-Deschamps ratio ≥1.15 (OR, 2.39; 95% CI, 1.09-5.22; P = .029), age <21 years (OR, 2.53; 95% CI, 1.11-5.77; P = .027), and high-grade trochlear dysplasia (OR, 4.17; 95% CI, 1.90-9.17; P < .001) were significantly associated with patellar redislocation. Based on the presence of these factors, the probability of dislocation after a first lateral patellar dislocation was 31.2% with no factors present, 36.6% with any 1 factor present, 71.7% with any 2 factors present, and 86.2% if all 3 conditions were present.

Conclusion: The results of this study indicated that patella alta, high-grade trochlear dysplasia, and age <21 years were independent risk factors for patellar redislocation after a first episode, with an additive effect when they were present together. This may help to guide the type of treatment for these patients.

Keywords: patella alta; patellar dislocation; patellar instability; risk factors; trochlear dysplasia.

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Conflict of interest statement

The authors declared that they have no conflicts of interest in the authorship and publication of this contribution. AOSSM checks author disclosures against the Open Payments Database (OPD). AOSSM has not conducted an independent investigation on the OPD and disclaims any liability or responsibility relating thereto.

Figures

Figure 1.
Figure 1.
STROBE (Strengthening the Reporting of Observational Studies in Epidemiology) flow diagram showing the sampling and inclusion of patients in the study.
See this image and copyright information in PMC

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