Long-Term Results of Meniscus Allograft Transplantation with Concurrent ACL Reconstruction
Abstract & Commentary
Synopsis: There is a slight deterioration in the clinical performance of meniscus allograft transplantation with concomitant ACL reconstruction at long-term follow-up.
Source: Wirth CJ, et al. Long-term results of meniscal allograft transplantation. Am J Sports Med. 2002;30:174-181.
The meniscus has an important role in the biomechanical properties of the knee joint including load bearing, load transmission, shock absorption, joint lubrication, and joint congruity. The present study is the continuation of the short-term results of mensicus allograft transplantation published by Milachowski and colleagues in 1989.1
From 1984 to 1986, the senior author performed 23 medial meniscus transplantations with concomitant ACL reconstruction. The average patient age was 29.6 years (range, 21-45 years) for 20 males and 3 females. The first follow-up evaluation was at 3 years postoperatively, at which point 19 patients agreed to undergo a second-look arthroscopy and radiographic evaluation. The second follow-up was at 14 years postoperatively (range, 12-15). At that time, 11 patients had plain radiographs, 9 patients had MRIs, and 2 patients agreed to a second-look arthroscopy. Two age-matched control groups, ACL reconstruction with meniscectomy (11 patients) or ACL reconstruction with intact meniscus (10 patients), were used to compare clinical outcomes with the meniscus transplant group. The control groups underwent the same preoperative and postoperative protocol.
For the meniscus transplant group, Lysholm scores were 59 points preoperatively, 84 points at 3 years postoperatively, and 75 points at 14 years postoperatively. The preoperative Tegner score increased from 1.0 to 5.1 points at 3 years postoperatively, then declined to 4.6 points at 14 years postoperatively. At every follow-up time point, patients with deep-frozen allografts had outcomes slightly better than patients with lyophilized allografts. Wirth and colleagues modified the Lysholm by eliminating the instability component, and the remaining score was thought to be able to measure the effect attributed to chondromalacia and/or osteoarthritis. With the modified Lysholm analysis, the patients with deep-frozen meniscus transplants and patients with intact meniscus performed significantly better than patients with lyophilized meniscus transplants and patients who had undergone meniscectomy (P < 0.05).
Five patients with deep-frozen allografts agreed to second-look arthroscopy at 3 years postoperatively. Two cases revealed a one-third reduction in size of the meniscus. MRI studies at 14 years demonstrated no further reduction in size or only one-third reduction compared to second-look arthroscopy. Fourteen patients with lyophilized allografts agreed to a second-look arthroscopy at 3 years postoperatively, and all menisci were reduced by one-third to two-thirds in size. At 14 years follow-up, all patients with lyophilized menisci had altered signal intensity on MRI, 2 patients had additional meniscus reduction, and 11 patients had grade 2 or 3 arthritic Fairbanks changes on x-ray. The only patients with arthritic changes belonged to the group implanted with lyophilized allografts.
Comment by Brian J. Cole, MD, MBA
The treatment of meniscal injuries has evolved over the last 30 years. Initially, the function of the meniscus was poorly understood, and total mensicectomies were routinely performed as the primary treatment of meniscal injury. However, contemporary understanding of the natural history and biomechanical consequences of the meniscectomized knee has led to the preference of meniscus preservation. In an effort to restore normal knee anatomy and biomechanics, meniscal allografts are used to replace native meniscus in select symptomatic individuals. Early results report excellent pain relief and improved function with the appropriate patient.
Wirth et al present their much-anticipated results of their long-term meniscus transplant patients. The patients with ACL reconstruction and deep-frozen meniscus allografts performed similarly to patients with ACL reconstruction with an intact meniscus, and patients with ACL reconstruction and lyophilized allografts had results comparable to patients with ACL reconstruction with meniscectomy. These results have led many implanters, including the reviewer, to use fresh-frozen or cryopreserved mensicus tissue. Interestingly, Wirth et al chose to analyze the subset of patients who had undergone meniscus transplant with concomitant ACL reconstruction. In doing so, it makes it more difficult to draw conclusions of the clinical performance attributed solely to the meniscus allograft. Wirth et al do comment in the discussion that patients who have undergone ACL reconstruction also show deterioration after 7 years; thus, it makes it difficult to determine whether the decline in clinical performance is due to the meniscus or ACL. Wirth et al, nonetheless, attempt to determine the theoretical results attributed to the meniscus by comparing the meniscus transplant and ACL reconstruction group to patients with ACL reconstructions with or without meniscectomies and by modifying the Lysholm scores to exclude any questions that involve joint stability.
Wirth et al do an excellent job of characterizing the difference between deep-frozen and lyophilized allografts by clinical scores, plain radiographs, second-look arthroscopy, and MRI studies. They do provide convincing evidence of the superiority of the deep-frozen allograft vs. the lyophilized allograft throughout the entire follow-up period. In sum, the long-term results of deep-frozen allografts show signs of slight deterioration but are relatively maintained over 14 years. Additional studies analyzing results of meniscus transplantation alone and comparing cryopreserved and fresh-frozen preservation methods may provide greater insight into meniscus allograft transplantation.
Author Acknowledgments: The reviewer would like to acknowledge Shane J. Nho, MS, for his assistance in preparation of this report.
Dr. Cole, Assistant Professor, Orthopaedic Surgery, Rush Presbyterian Medical Center, Midwest Orthopaedics, Chicago, IL, is Associate Editor of Sports Medicine Reports.
Reference
1. Milachowski KA, Weismeier K, Wirth CJ. Homologous meniscus transplantation. Experimental and clinical results. Int Orthop. 1989;13:1-11.
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