OBJECTIVE: To evaluate the prevalence of predisposing factors for femoropatelar instability (dysplasia of the trochlea, high patella, TTTG, and patellar tilt) in a group of patients in outpatient follow-up. METHODS: 70 patients were evaluated; 52 (74.28 %) female and 18 (25.72 %) male, with an average age of 17.71 years and a total of 127 knees. The evaluation by imaging was carried out through radiologic examination and computerized tomography. The femoropatelar instabilities were classified according to Henri Dejour's classification (major, objective and potential instability). The trochlear dysplasia was classified according to David Dejour's classification (type A, B, C, D). RESULTS: Trochlear dysplasia was observed in 118 knees (92.91%), with 91 knees (77.11%) being of type A and B. The average for patellar height was 1.23, with 44 (34.64%) considered high patellas and 83 (65.36%) within the normal range. Abnormal patellae tilt was found in 92 knees (72.44%) and an elevation of TTTG in 63 knees (49.60%). The was a prevalence of objective instabilities with 89 knees (70.07%). In relation to the association of predisposing factors, 117 knees (92.13%) presented more than one factor. CONCLUSIONS: Femoropatelar instability is a multifactorial disease, with trochlear disorders being the most frequent, and there is a strong association between two or more predisposing factors.
Knee; Patella; Joint instability
