Prevalence of trochlear dysplasia in symptomatic isolated lateral patellofemoral osteoarthritis: Transverse study of 101 cases.

INTRODUCTION

Patellofemoral osteoarthritis (PFOA) is usually associated with femorotibial osteoarthritis; isolated forms involve several specific risk factors. Trochlear dysplasia (TD) alters stress patterns in the patellofemoral joint, inducing PFOA. The association of TD and isolated PFOA was analyzed without distinguishing medial facet, global and lateral facet involvement. The study hypothesis was that TD prevalence is high in isolated lateral PFOA (ILPFOA). The aim of the study was to assess TD prevalence in a symptomatic ILPFOA population and identify risk factors.

PATIENTS AND METHODS

Eighty-four patients (101 knees) underwent lateral vertical patellectomy (LVP) for symptomatic ILPFOA between November 1998 and September 2019. Demographic, clinical and radiographic data were collected retrospectively from preoperative records. TD was analyzed by 2 blinded surgeons on lateral radiographs.

RESULTS

TD prevalence was 88.1%. TD was significantly more advanced in patients under 45 years of age at surgery (64.5% stage 2 or 3; p=0.019). Non-TD cases showed significantly more frequent valgus deformity (83.3%; p=0.042) and overweight (BMI, 32±4.1; p<0.001).

CONCLUSION

TD is a known risk factor for PFOA, present in almost 9 in 10 cases in the present series of ILPFOA. These findings reinforce the hypothesis that it plays a role in onset of ILPFOA. TD also induces early pain, leading to surgery. Overweight and valgus deformity are contributing factors for ILPFOA.

LEVEL OF EVIDENCE

IV; transverse study.