Long-Term Durability of Autologous Chondrocyte Transplantation
April 1, 2002 4 minutes read
Long-Term Durability of Autologous Chondrocyte Transplantation
Abstract & Commentary
Synopsis: Fifty-one of 61 patients reported good-to-excellent clinical results at 5-11 years follow-up. Using an electromechanical indentation probe, implanted areas were 90% of normal cartilage stiffness. Eight of 11 biopsy specimens demonstrated hyaline-like features by histological and immunohistochemical analyses.
Source: Peterson L, et al. Am J Sports Med. 2002;30:2-12.
The initial treatment of focal chondral defects involved marrow stimulating techniques that resulted in fibrous repair tissue that lacks the mechanical durability of normal articular cartilage. The fate of these lesions carries a poor long-term prognosis, and many patients required additional surgical intervention or activity modification. In 1994, Brittberg and colleagues reported an initial series of 16 patients with 14 demonstrating good-to-excellent results, and 11 of 15 biopsy specimens revealing hyaline-like cartilage.1 The purpose of the present study was to evaluate the long-term clinical data, to characterize histological and immunohistochemical features of implanted grafts, and to measure the biomechanical properties of implanted grafts.
Between 1987 and 1994, 61 patients were transplanted and divided into separate groups by type and location of defect: group 1, isolated femoral condyle lesions; group 2, osteochondritis dissecans lesions; group 3, patellar lesions; group 4, femoral condyle lesions with ACL reconstructions. Patients’ clinical status was assessed annually by 5 scoring systems including Lysholm and Gillquist, the modified Cincinnati knee score, the overall Cincinnati knee-rating score, the Tegner-Wallgren activity score, and the overall Brittberg clinical grading scores.
Eleven of 18 patients from groups 1, 2, and 4 that were randomly selected agreed to undergo a second-look arthroscopy for gross appearance, biomechanical testing, and histology of an implanted biopsy specimen. Patients from group 3 were not included due to the inability of the electromechanical indenter probe to access the patellar surface. At an average follow-up of 54 months (range, 33-84 months), biopsies were obtained and scored grossly with a 12-point scoring system, and microscopically by 2 blinded pathologists. The degree of staining for each specimen was assessed for collagen type I, collage type II, cartilage oligomeric matrix protein, and aggrecan. Each graft was then classified as hyaline-like, fibrous, or mixed tissue. The electromechanical indenter probe (Artscan Inc, Kuopio, Finland) was used to measure the biomechanical properties of the implanted graft and normal surrounding cartilage.
Fifty-one of 61 patients reported good or excellent results at between 5 and 11 years. Overall, 10 of 61 (16%) patients failed treatment, with the lower failure rates occurring in the isolated femoral condylar lesion (11%) and osteochondritis dissecans (14%) groups, compared to the concomitant ACL reconstruction (18%) and patellar lesion groups (24%). All patients who failed had fair to poor results at 2 years, and 7 of 10 failures occurred by 2 years postimplantation.
Of the 12 biopsy specimens, 8 had hyaline-like features with positive type II collagen immunohistochemical staining, and 4 demonstrated fibrous features with type I collagen staining. The grafted areas were generally well integrated with the surrounding normal cartilage and well anchored to the subchondral bone. Most biopsy specimens demonstrated a superficial fibrous surface most likely as a result of the periosteal patch. Samples demonstrating hyaline-like cartilage demonstrated twice the stiffness of those with fibrous features.
The scientific and clinical results suggest that autologous chondrocyte transplantation can be a long-term solution for localized articular lesions. In most cases, failed grafts will manifest clinically within 2 years of implantation. Patients with good or excellent clinical results by 2 years will most likely maintain their clinical performance over a longer period of time.
Comment by Brian J. Cole, MD, MBA
Peterson and colleagues have done an exceptional job describing the long-term durability of autologous chondrocyte transplantation by clinical, histological, immunohistochemical, and biomechanical analyses. Collagen subtyping supported the presence of type I collagen in fibrous specimens and type II collagen in specimens with hyaline-like features. Stiffness measurements supported more normal biomechanical features of the hyaline-like specimens. Despite the presence of fibrous tissue, good-to-excellent results were still achievable. Clearly, the variability in sampling error that occurs with biopsy and stiffness testing must be considered when using these tools as primary outcome variables. Despite these limitations, the clinical results continue to remain promising beyond 2 years providing informative data for the majority of patients treated in the United States with autologous chondrocyte implantation who are still in the early follow-up period.
Dr. Cole, Assistant Professor, Orthopaedic Surgery, Rush Presbyterian Medical Center, Midwest Orthopaedics, Chicago, IL, is Associate Editor of Sports Medicine Reports.
Author Acknowledgment: The reviewer would like to acknowledge Shane J. Nho, MS, for his assistance in preparation of this report.
Reference
1. Brittberg M, et al. N Engl J Med. 1994;331:889-895.
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