The purpose of this study was to reveal the correlation between the type of lesion and the depth of osteoarthritic (OA) changes in the patello-femoral (PF) joint and its bony morphological characteristics using computed tomography (CT) data.
Eighty-seven cadaveric knees were included in this study with median age of 83 years (62-97). OA depth evaluation was performed following Outerbridge's classification. Patella OA lesions were classified macroscopically using Han's method: type (1) no or minimal lesion, type (2) medial facet lesion without involvement of the ridge, type (3) lateral facet lesion without involvement of the ridge, type (4) lesion involving the ridge only, type (5) medial facet lesion with involvement of the ridge, type (6) lateral facet lesion with involvement of the ridge, and type (7) global lesion. Femoral-side OA lesions in the PF joint were classified using a modified Chang's method. Type (1) no or minimal lesion, type (2) medial facet lesion, type (3) centre of patella groove lesion, type (4) lateral facet lesion, and type (5) global lesion. Whole-body CTs of all cadavers were taken before knee dissection. Using the CT data, patella morphology was evaluated following Wiberg's classification. Femoral sulcus angle (SA), sulcus depth (SD), and sulcus width (SW) were also measured using CT data.
The measured SA, SD, and SW were 144.8° ± 7.2°, 7.0 ± 1.6 mm and 3.4 ± 0.3 mm, respectively. When patella OA depth was divided into grades 1-2 (n = 30) and grades 3-4 (n = 57), the SD of grade 1-2 knees was 6.5 ± 1.3 mm, and the SD of grade 3-4 knees was 7.3 ± 1.6 mm, constituting a significant difference (p = 0.01). No significant difference in either SA or SW was observed between the two groups. Patella OA lesion, femoral-side OA lesion, and depth were not affected by SA, SD, or SW. Wiberg's classification also showed no significant correlation with PF-OA.
Deep SD was significantly correlated with the incidence of severe patella OA. Wiberg's classification, SA, and SW were not correlated with PF-OA. For clinical relevance, there is a risk of PF-OA progression in patients with deep SD, and treatment should be applied accordingly.