Background

Autologous Chondrocyte Implantation (ACI) is a procedure which is gaining acceptance for the treatment of cartilage defects in the knee with good results and a long term durable outcome. Its use in other joints has been limited, mainly to the ankle. We aimed to assess the outcome of ACI in the treatment of chondral and osteochondral defects in the hip.

Introduction: Autologous chondrocyte implantation (ACI) has been used most commonly as a treatment for cartilage defects in the knee and there are few studies of its use in other joints. There is only one published report of its use in the hip. Is there a role for ACI of the hip?

Materials and Methods: We describe fourteen consecutive patients studied prospectively with chondral or osteochondral lesions of the femoral head that underwent ACI and were prospectively reviewed with a follow up of 5 years (mean 30 months).

Three patients presented with Perthes and five with AVN. Four had chondral loss following trauma and one presented with an area of bone loss in a hip with congenital dysplasia. Defect size was a mean 6.2 cm2.

Pre-operatively hip function was assessed by the patient using the Harris Hip Score and MRI. Postoperatively these were repeated at 1 year and hip scores repeated annually.

Hip arthroscopy and cartilage biopsy provided Cells for culture in a GMP laboratory where passage numbers were limited to two. Three weeks later by open surgery, all unstable cartilage was excised, the base was debrided or excised and bone graft applied, and suture of a membrane of periosteum or collagen membrane over the defect undertaken. A mean 5.2 million chon-drocytes were inserted beneath this patch following a test of the seal.

Results: Ten of the fourteen patients improved at one year, with a mean rise in Harris Hip score from 57 to 63 points. Five patients underwent arthroscopic examination at one year and in four there was evidence of good integration of the new cartilage. In one patient arthros-copy was difficult due to previous trauma. One patient developed AVN as a post-operative complication following a posterior approach. Four patients have progressed to hip replacement or resurfacing but it is of note that all these patients had cyst formation pre-operatively.

Conclusion: The short-term results of ACI for osteo-chondral lesions of the hip suggest that if good early results are obtained they are observed to continue out to 5 years. There is a high failure rate in those with pre-operative cyst formation in the hip