Chondrocyte transplant a potential option for talar cartilage defects

At three months postop, all patients showed osteotomy site union. Most were satisfied with their results.

Autologous chondrocyte transplantation may be an effective option for treating patients with full-thickness talar cartilage defects, suggests a study by German researchers.

Mike H. Baums, MD, an orthopedic surgeon at Georg-August-Universität Göttingen in Göttingen, Germany, conducted the prospective study with colleagues at the university’s departments of orthopedic surgery and radiology. The researchers evaluated the midto long-term results of autologous chondrocyte transplantation (ACT) for treating isolated osteochondral defects in 12 stable ankles of seven women and five men. These patients had a mean age of 29.7 years (range, 18 to 42 years); six patients participated in light sports and six participated in competitive sports, according to the study, published in the American edition of the Journal of Bone and Joint Surgery.

At an average 36 months final follow-up, seven patients had nearly congruent joint surfaces with grafts integrating with adjacent native cartilage and subchondral bone. These seven patients also had regained their original articular contour. Another four patients had irregular surfaces, but grafts did show integration with subchondral bone.

Surgeons elected not to perform second-look arthroscopies because all patients showed good results clinically. “Thus it is not possible to discuss the histological characteristics of the repair tissue,” they said. “Our results are promising, but it is difficult to state with certainty the efficacy of this procedure because of the small number of patients in our study,” they added.

For their clinical evaluations, Baums and colleagues used the Hannover ankle scoring system and the American Orthopaedic Foot and Ankle Society (AOFAS) ankle-hindfoot scale. They also obtained MRIs preoperatively, at 12 months postop and at final follow-up.

In all cases, surgeons used essentially the same ACT procedure described in 2002 by Koulalis et al in Clinical Orthopedics and Related Research. However, one patient also required reconstruction of a subchondral talar cyst, and another required a so-called “sandwich procedure” to reconstruct a subchondral osseous defect. In this patient, surgeons curetted to expose healthy, bleeding cancellous bone, filled the defect with autogenous cancellous bone graft, and covered the lesion with two layers of periosteum. They then injected cultured chondrocyte cells between the two periostal layers, according to the study.

Following surgery, patients remained nonweight-bearing for six weeks, progressing to full weight-bearing by 10 weeks. Patients also received continuous passive motion for four weeks and began an active supervised exercise program immediately postop, according to the study.

No patients had serious complications, such as deep vein thrombosis, joint infection or nonunion.

At three months postop, radiography showed union of all osteotomy sites. Nine patients subjectively rated their opinion of their results as very satisfied and three as satisfied. Additionally, all patients who had participated in competitive sports could return too their full level of activity, the authors said.

At final follow-up, Visual Analog Scale-measured pain had improved to a mean of 1.3 points from 7.8 points preoperatively. The mean Hannover score significantly improved to 85.5 points from 40.4 points preoperatively (P<.001). And the mean AOFAS score significantly improved to 88.4 points from 43.5 points at preop (P<.001), according to the study.

“Despite our small patient group, we think that autologous chondrocyte transplantation is valuable for the treatment of focal cartilage lesions of the talar dome, especially in patients for whom previous traditional surgical attempts of cartilage resurfacing have failed,” they said.

“Prospective, randomized, long-term studies with greater numbers of patients are needed to establish clinical relevance and validate the efficacy and safety of this method,” they said.

For more information:
Baums MH, Heidrich G, Schultz W, et al. Autologous chondrocyte transplantation for treating cartilage defects of the talus. J Bone Joint Surg Am. 2006;88:303-308.