A flatter proximal trochlear groove is associated with patella cartilage loss

PURPOSE: The bony articular surface contributes to a joint's congruency, and it might be a determinant of structural change. The aim of this longitudinal study was to determine (i) whether the angle of the trochlear groove is associated with the rate of loss of patella cartilage volume for 2 yr and (ii) whether this association is influenced by particular modifiable and nonmodifiable factors. METHODS: A total of 297 community-based adults with no history of knee pathologic disease were recruited at baseline (2003-2004), and 271 of these subjects were reexamined at follow-up (2006-2007). Magnetic resonance imaging was performed at baseline and follow-up to determine the change in patella cartilage volume, whereas baseline images were used to assess trochlear groove angles. A baseline questionnaire determined participation in vigorous physical activity. RESULTS: For every 1° increase in the proximal trochlear groove angle at baseline, there was an associated 1.12-mm ³ (95% confidence interval (CI) = 0.00-2.24 mm ³) increase in the annual rate of patella cartilage volume loss. There was a trend for this effect to occur for males, as well as people participating in vigorous physical activity (all P ≤ 0.07). Males who exercised vigorously were more adversely affected (5.0 mm ³ per annum (95% CI = 0.5-9.4 mm per annum)) than males who did not exercise vigorously (0.6 mm per annum (95% CI = -2.1 to 3.3 mm per annum)). CONCLUSIONS: A more flattened proximal trochlear groove is associated with increased patella cartilage volume loss, particularly for physically active men. Our results suggest that lifestyle factors, such as physical activity, may modify the association between joint incongruity and cartilage loss and can be further affected by subjects' characteristics such as gender. Understanding these complex interactions will help optimize strategies to maintain patellofemoral joint health.