Simon Görtz

Allografts in articular cartilage repair

Hyaline articular cartilage is an avascular and insensate tissue with a distinct structural organization, which provides a low-friction and wear-resistant interface for weight-bearing surface articulation in diarthrodial joints. Ideally, articular cartilage is maintained in homeostasis over the lifetime of an individual, with its biomechanical properties inherently suited to transmit a variety of physiologic loads through a functional range of motion. However, in the skeletally mature individual, articular cartilage does not heal effectively when injured. Although several restorative options for biomimetic replacement in acquired articular cartilage defects do exist, fresh osteochondral allografting currently remains the only technique that restores anatomically appropriate, mature hyaline cartilage in large articular defects. The fundamental paradigm of fresh osteochondral allografting is the transplantation of mature orthotopic hyaline cartilage, with viable chondrocytes that survive hypothermic storage and subsequent transplantation while maintaining their metabolic activity and sustaining the surrounding collagen matrix. Fresh osteochondral allografts have application in the treatment of a wide spectrum of articular pathology, particularly conditions that include both an osseous and a chondral component. The surgical procedure for femoral condyle lesions is straightforward but demands precision to achieve reproducible results and to minimize early graft failures related to surgical technique. As with other cartilage-restorative procedures, the indications for use of fresh osteochondral allografts are still being expanded. Many clinical and basic scientific studies support the theoretical foundation and efficacy of small fragment allografting, although more scientific validation of empirical clinical practice is still needed.

Chondrocyte Viability is Higher after Prolonged Storage at 37°C than at 4 C for Osteochondral Grafts

Background Osteochondral allografts are currently stored at 4°C for 2 to 6 weeks before implantation. At 4°C, chondrocyte viability, especially in the superficial zone, deteriorates starting at 2 weeks. Alternative storage conditions could maintain chondrocyte viability beyond 2 weeks, and thereby facilitate increased graft availability and enhanced graft quality. Purpose The objective of the study was to determine the effects of prolonged 37°C storage compared with traditional 4°C storage on chondrocyte viability and cartilage matrix content. Study Design Controlled laboratory study. Methods Osteochondral samples from humeral heads of adult goats were analyzed (i) fresh, or after storage in medium for (ii) 14 days at 4°C including 10% fetal bovine serum, (iii) 28 days at 4°C including 10% fetal bovine serum, (iv) 28 days at 37°C without fetal bovine serum, (v) 28 days at 37°C including 2% fetal bovine serum, or (vi) 28 days at 37°C including 10% fetal bovine serum. Portions of samples were analyzed by microscopy after LIVE/DEAD staining to determine chondrocyte viability and density, both en face (to visualize the articular surface) and vertically (overall and in superficial, middle, and deep zones). The remaining cartilage was analyzed for sulfated glycosaminoglycan and collagen. Results The 37°C storage maintained high chondrocyte viability compared with 4°C storage. Viability of samples after 28 days at 37°C was ˜80% at the cartilage surface en face, ˜65% in the superficial zone, and ˜70% in the middle zone, which was much higher than ˜45%, ˜20%, and ˜35%, respectively, in 4°C samples after 28 days, and slightly decreased from ˜100%, ˜85%, and ˜95%, respectively, in fresh controls. Cartilage thickness, glycosaminoglycan content, and collagen content were maintained for 37°C and 4°C samples compared with fresh controls. Conclusion The 37°C storage of osteochondral grafts supports long-term chondrocyte viability, especially at the vulnerable surface and superficial zone of cartilage. Clinical Relevance Storage of allografts at a physiologic temperature of 37°C may prolong storage duration, improve graft availability, and improve treatment outcomes.

Fresh Osteochondral Allografting for Osteochondral Lesions of the Talus

Background: Osteochondral lesions of the talus (OLT) are relatively common sequelae of traumatic injuries involving the talus. We report on clinical outcomes of osteochondral allografting (OCA) of the talus for refractory, symptomatic OLT. Materials and Methods: OCA was performed in 12 ankles in 11 patients with OLT. All involved partial, unipolar grafts of the talar dome, implanted through an anterior approach without osteotomy, under temporary distraction. Clinical evaluation was performed utilizing the Olerud-Molander Ankle Score (OMAS). Subjective outcome measures included patient questionnaires evaluating pain, function, and satisfaction. Eleven patients (seven males, four females) had a mean age of 35.5 (range, 26 to 57) years. One patient had bilateral involvement. Six OLT affected the medial, six the lateral talar dome. Patients had an average of 1.8 previous surgeries (range, 1 to 5). Mean followup was 38 (range, 24 to 107) months. Results: Mean OMAS improved from 28 to 71 points (p < 0.05). Three had further surgery; overall graft survival rate was 10/12. Of surviving grafts, 30% recorded excellent (OMAS: 100 to 91 points), 20% good (OMAS: 90 to 61 points), 30% fair (OMAS: 60 to 31 points), and 20% poor (OMAS: 30 to 0 points) outcomes. All non-failing patients completed questionnaires; 90% were satisfied, 80% reported reduced pain, and 60% improved function. Conclusion: OCA achieved good to excellent results in five of 12 patients, resulting in significant improvement in function and pain with good patient satisfaction. All but one patient avoided arthrodesis. Partial talus OCA is a reasonable treatment option for appropriately selected patients with unipolar OLT. Level of Evidence: IV, Retrospective Case Series

Fresh Osteochondral Allograft Transplantation for Isolated Patellar Cartilage Injury

Background: The treatment of patellofemoral cartilage injuries can be challenging. Osteochondral allograft (OCA) transplantation has been used as a treatment option for a range of cartilage disorders. Purpose: To evaluate functional outcomes and survivorship of the grafts among patients who underwent OCA for patellar cartilage injuries. Study Design: Case series; Level of evidence, 4. Methods: An institutional review board–approved OCA database was used to identify 27 patients (28 knees) who underwent isolated OCA transplantation of the patella between 1983 and 2010. All patients had a minimum 2-year follow-up. The mean age of the patients was 33.7 years (range, 14-64 years); 54% were female. Twenty-six (92.9%) knees had previous surgery (mean, 3.2 procedures; range, 1-10 procedures). The mean allograft area was 10.1 cm2 (range, 4.0-18.0 cm2). Patients returned for clinical evaluation or were contacted via telephone for follow-up. The number and type of reoperations were assessed. Any reoperation resulting in removal of the allograft was considered a failure of the OCA transplantation. Patients were evaluated pre- and postoperatively using the modified Merle d’Aubigné-Postel (18-point) scale, the International Knee Documentation Committee (IKDC) pain, function, and total scores, and the Knee Society function (KS-F) score. Patient satisfaction was assessed at latest follow-up. Results: Seventeen of the 28 knees (60.7%) had further surgery after the OCA transplantation; 8 of the 28 knees (28.6%) were considered OCA failures (4 conversions to total knee arthroplasty, 2 conversions to patellofemoral knee arthroplasty, 1 revision OCA, 1 patellectomy). Patellar allografting survivorship was 78.1% at 5 and 10 years and 55.8% at 15 years. Among the 20 knees (71.4%) with grafts in situ, the mean follow-up duration was 9.7 years (range, 1.8-30.1 years). Pain and function improved from the preoperative visit to latest follow-up, and 89% of patients were extremely satisfied or satisfied with the results of the OCA transplantation. Conclusion: OCA transplantation was successful as a salvage treatment procedure for cartilage injuries of the patella.

Osteochondral allograft transplantation in cartilage repair: Graft storage paradigm, translational models, and clinical applications

The treatment of articular cartilage injury and disease has become an increasingly relevant part of orthopaedic care. Articular cartilage transplantation, in the form of osteochondral allografting, is one of the most established techniques for restoration of articular cartilage. Our research efforts over the last two decades have supported the transformation of this procedure from experimental “niche” status to a cornerstone of orthopaedic practice. In this Kappa Delta paper, we describe our translational and clinical science contributions to this transformation: (1) to enhance the ability of tissue banks to process and deliver viable tissue to surgeons and patients, (2) to improve the biological understanding of in vivo cartilage and bone remodeling following osteochondral allograft (OCA) transplantation in an animal model system, (3) to define effective surgical techniques and pitfalls, and (4) to identify and clarify clinical indications and outcomes. The combination of coordinated basic and clinical studies is part of our continuing comprehensive academic OCA transplant program. Taken together, the results have led to the current standards for OCA processing and storage prior to implantation and also novel observations and mechanisms of the biological and clinical behavior of OCA transplants in vivo. Thus, OCA transplantation is now a successful and increasingly available treatment for patients with disabling osteoarticular cartilage pathology.

Bipolar fresh osteochondral allografting of the tibiotalar joint

BACKGROUND Tibiotalar arthritis in the young, active patient is a debilitating condition with limited treatment options. Bipolar tibiotalar fresh osteochondral allograft transplantation was conceived as a possible alternative to arthrodesis and arthroplasty. We reported our experience with bipolar ankle osteochondral allografts for the treatment of tibiotalar joint arthritis. METHODS Between 1999 and 2008, we performed bipolar ankle allografts in eighty-eight ankles (eighty-four patients). Eighty-six ankles (eighty-two patients) had a minimum follow-up duration of two years. The mean patient age was forty-four years and 52% of the patients were male. Evaluation included frequency and type of reoperations, the Olerud-Molander Ankle Score, pain, function, and patient satisfaction. Radiographs were evaluated for graft healing, joint space narrowing, and graft collapse. RESULTS The mean duration of follow-up was 5.3 years (range, two to eleven years). Thirty-six (42%) of the eighty-six ankles that had undergone allograft had further surgery since implantation. Of the eighty-six ankles, twenty-five ankles (29%) had undergone graft-related reoperations and were considered clinical failures (ten underwent revision allografts, seven underwent arthrodeses, six underwent conversions to total ankle arthroplasty, and two underwent below-the-knee amputations) and eleven ankles (13%) had had reoperations that were not necessarily related to the graft (e.g., implant removal, debridement, synovectomy, or distraction). Survivorship of the osteochondral allograft was 76% at five years and 44% at ten years. The mean Olerud-Molander Ankle Score was 61 points at the time of the latest follow-up. The majority of patients reported satisfaction (92%) with osteochondral allograft transplantation and less pain (85%) and improved function (83%) after the procedure. CONCLUSIONS Transplantation of a fresh bipolar ankle osteochondral allograft for the treatment of tibiotalar arthritis resulted in acceptable outcomes in this difficult population, with most patients having improved objective and subjective outcome measures. Subjective satisfaction was high in spite of the 29% clinical failure rate. Osteochondral allograft failure did not limit further surgical options. We concluded that transplantation of a bipolar ankle allograft is a useful alternative in carefully selected patients with advanced tibiotalar arthritis.

Fresh Osteochondral Allograft Transplantation for Bipolar Reciprocal Osteochondral Lesions of the Knee

Background: Osteochondral allograft (OCA) transplantation is an effective treatment option for chondral and osteochondral defects of the knee. Hypothesis: Patients treated with OCAs for reciprocal bipolar lesions of the knee would demonstrate significant clinical improvement. Study Design: Case series; Level of evidence, 4. Methods: Between 1983 and 2010, OCAs were implanted for bipolar chondral lesions in 46 patients (48 knees). The 21 male and 25 female patients averaged 40 years of age (range, 15-66 years). Thirty-four lesions were tibiofemoral, and 14 were patellofemoral. Forty-two knees (88%) had undergone a mean of 3.4 previous surgeries (range, 1-8). The mean allograft area was 19.2 cm2. Clinical evaluation included the modified Merle d’Aubigné-Postel (18-point), International Knee Documentation Committee (IKDC) pain and function, and Knee Society function (KS-F) scores. Further surgeries on the operative joint were documented. Results: Survivorship of the bipolar OCA was 64.1% at 5 years. Thirty knees underwent further surgery; 22 knees (46%) were considered failures (3 OCA revisions, 14 total knee arthroplasties, 2 unicondylar arthroplasties, 2 arthrodeses, and 1 patellectomy). Among patients whose OCA was still in situ at follow-up, the mean follow-up was 7 years (range, 2.0-19.7 years). The mean 18-point score improved from 12.1 to 16.1; 88% (23/26 knees) of surviving allografts scored ≥15. The mean IKDC pain score improved from 7.5 to 4.7, and the mean IKDC function score improved from 3.4 to 7.0. The mean KS-F score improved from 70.5 to 84.1. Conclusion: Osteochondral allograft transplantation is a useful salvage treatment option for reciprocal bipolar cartilage lesions of the knee. High reoperation and failure rates were observed, but patients with surviving allografts showed significant clinical improvement.

The Role of Immunologic Response in Fresh Osteochondral Allografting of the Knee

Background: Osteochondral allografting, a restorative treatment option for articular cartilage lesions in the knee, involves transplantation of fresh osteochondral tissue with no tissue matching. Although retrieval studies have not consistently shown evidence of immunologic response, development of anti–human leukocyte antigen class I cytotoxic antibodies has been observed in allograft recipients. Hypothesis: Postallograft antibody formation is related to graft size and may affect clinical outcome. Study Design: Case-control study; Level of evidence, 3. Methods: This study retrospectively compared 42 antibody-positive postallograft patients with 42 antibody-negative patients. Groups were matched for age, sex, and body mass index but not intra-articular disease severity. Seventeen patients (20%) were lost to follow-up. Of the remaining 67 patients (33 antibody-positive and 34 antibody-negative), average follow-up time was 50.3 months (range, 24-165 months). Mean age was 38.1 years (range, 15-68 years) with 58% being male. Graft area was categorized as small (<5 cm2), medium (5-10 cm2), or large (>10 cm2). Graft survival and Knee Society function scores were used to measure clinical outcome. Results: Of the 84 patients, 80 had graft area data. Of 27 patients with large graft area, 19 (70%) had positive postoperative antibody screens, compared with 1 of 16 (6%) with small graft area (P < .001). Graft survival rates in the antibody-positive and antibody-negative groups were 64% and 79%, respectively (P = .152). Mean postoperative Knee Society function scores in surviving antibody-positive and antibody-negative groups were 88.3 and 84.6 points, respectively (P = .482). Conclusion: Antibody development after fresh, non-tissue-matched osteochondral allograft transplants in the knee appears related to graft size. No difference was observed in clinical outcome between groups. Graft survival is multifactorial, and the effect that the immunologic response has on clinical outcome merits further investigation.

Osteochondral and Meniscal Allograft Transplantation in the Football (Soccer) Player

Knee injuries are common in football, frequently involving damage to the meniscus and articular cartilage. These injuries can cause significant disability, result in loss of playing time, and predispose players to osteoarthritis. Osteochondral allografting is an increasingly popular treatment option for osteoarticular lesions in athletes. Osteochondral allografts provide mature, orthotopic hyaline cartilage on an osseous scaffold that serves as an attachment vehicle, which is rapidly replaced via creeping substitution, leading to reliable graft integration that allows for simplified rehabilitation and accelerated return to sport. The indications for meniscal replacement in football players are currently still evolving. Meniscus allografts offer potential functional, analgesic, and chondroprotective benefits in the meniscectomized knee. In the player at the end of his or her professional/competitive career, meniscal allografts can play a role in averting progression of chondropenia and facilitating knee function and an active lifestyle. This article is intended to present a concise overview of the limited published results for osteochondral and meniscal allografting in the athletic population and to provide a practical treatment algorithm that is of relevance to the clinician as well as the patient/football player, based on current consensus of opinion.

Osteochondral Allograft Transplantation: The Rationale and Basic Science

The use of allograft tissues for orthopedic reconstructions has seen a dramatic rise in the past decade. For example, allograft bone is widely used to fill bone voids, provide temporary structural support, and to induce local tissue repair. One application for the use of allograft tissues is to attempt to reconstruct the articular surface in patients with chondral or osteochondral lesions. As our understanding of the basic science of allograft tissues has grown, we have seen an evolution of its use from primarily a structural entity into one in which these tissues are implanted with the intent of preserving their biological activity and function, as well.