Preserving Hip Stability Yields Better Cartilage Repair With Microfracture Treatment: A Rabbit Study

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.

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.

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).

Preservation of the hip stability enhances the effectiveness of microfracture treatment, promoting superior cartilage regeneration compared with microfracture alone in a rabbit model.

Maintaining or restoring the hip stability leads to improved cartilage healing beyond the effect of isolated microfracture.