Abstract
PURPOSE: To compare the individual and combined effects of microfracture and hip stability achieved through preservation of the soft tissue on cartilage repair in rabbit femoral head osteochondral defect. METHODS: Twenty-four male New Zealand white rabbits were divided into 4 groups. In group 0, the untreated right femoral heads of 6 rabbits served as healthy controls. Osteochondral defects (5 × 3 mm) were created on the left femoral heads of all 24 animals. Group 1 (n = 6) received microfracture, with the labrum preserved and capsule repaired. Group 2 (n = 6) received microfracture, but the labrum was excised and the capsule left unrepaired; additionally, a 2 × 6-mm portion of the capsule was excised. Group 3 (n = 6) had no microfracture, but the labrum and capsule were preserved. Group 4 (n = 6) had no microfracture and additionally the labrum was excised and capsule left unrepaired; as in Group 2, a 2 × 6-mm portion of the capsule was also excised. After 4 weeks, cartilage healing was assessed using the International Cartilage Regeneration & Joint Preservation Society (ICRS) and modified O'Driscoll scores and via immunohistochemically with collagen type I, II, and aggrecan staining. RESULTS: Group 1 demonstrated significantly better cartilage healing than the other groups (P < .05), with better outcomes in at least one of the following parameters: ICRS score, defect filling ratio, or modified O'Driscoll score. Group 3 scored better than group 2 in ICRS assessment (P = .048). Type II collagen and aggrecan expression were significantly greater in Group 1 than in groups 2 and 4 (P < .05). CONCLUSIONS: Preservation of the hip stability enhances the effectiveness of microfracture treatment, promoting superior cartilage regeneration compared with microfracture alone in a rabbit model. CLINICAL RELEVANCE: Maintaining or restoring the hip stability leads to improved cartilage healing beyond the effect of isolated microfracture.