Allan E. Gross

Long-term followup of the use of fresh osteochondral allografts for posttraumatic knee defects.

Posttraumatic osteochondral defects of the distal femur or proximal tibia pose a reconstructive challenge for the young active patient. Fresh osteochondral allografts have been used to reconstruct these defects and this report deals with the long-term clinical and radiographic follow-up in this patient population. This is a prospective nonrandomized study. Sixty patients with an average followup of 10 years received femoral condylar grafts. Twelve grafts failed, requiring removing of the graft in three patients and conversion to total knee replacement in nine patients. Kaplan-Meier survivorship showed 95% graft survival at 5 years and 85% at 10 years. Sixty-five patients received fresh osteochondral allografts to reconstruct the tibial plateau with an average followup of 11.8 years. In this group of patients, conversion to total knee arthroplasty was done in 21 patients at a mean interval of 9.7 years. Survival analysis revealed 95% survival at 5 years, 80% at 10 years, and 65% at 15 years. Through our long-term prospective study, we confirm the value of fresh osteochondral allografts to reconstruct articular defects of the knee in the young active patient. Level of Evidence: Therapeutic study, Level II-1 (prospective cohort study). See the Guidelines for Authors for a complete description of levels of evidence.

The viability of articular cartilage in fresh osteochondral allografts after clinical transplantation

The articular cartilage of four fresh osteochondral allografts was biopsied after transplantation, and its viability was studied by autoradiography. The biopsy specimens were labeled with both 3H-cytidine, for newly synthesized ribonucleic acid, and 35S-sulphate, for newly synthesized proteoglycans. The cartilage of a lateral humeral condylar graft at twelve months had 96 to 99 per cent labeled chondrocytes, the articular cartilage of a medial femoral condylar graft at twenty-four months showed 69 to 78 per cent labeled chondrocytes, and the cartilage of a medial tibial-plateau graft at forty-one months had 90 per cent labeled cells. At six years, a lateral tibial-plateau graft had 37 per cent labeled chondrocytes.

Osteochondral defects of the talus treated with fresh osteochondral allograft transplantation.

Between 1980 and 1996, 9 patients with osteocartilagenous lesions of the talus were treated surgically using fresh osteochondral allograft transplantation. In 8 cases the reason for surgery was osteochondritis dissecans (4 of these cases had a previous traumatic injury). In 1 case a fresh osteochondral allograft of the talus was required following a traumatic open fracture of the talus sustained in a motor vehicle accident. Of these 9 grafts, 6 grafts remain in situ with a mean survival of 11 years (range 4 to 19). In the three cases requiring fusion the reason for surgery was not related to arthritic deterioration but due to resorption and fragmentation of the graft.

Periprosthetic Femoral Fractures Around Well-Fixed Implants:Use of Cortical Onlay Allografts with or without a Plate

Background: Periprosthetic femoral fractures around hip replacements are increasingly common. When the femoral component is stable, open reduction and internal fixation is recommended in all but exceptional cases. The purpose of this study was to evaluate the outcome of treatment of fractures around stable implants with cortical onlay strut allografts with or without a plate. Methods: A survey of our four centers identified forty patients with a fracture around a well-fixed femoral stem treated with cortical onlay strut allografts without revision of the femoral component. There were fourteen men and twenty-six women, with an average age of sixty-nine years. Nineteen patients were treated with cortical onlay strut allografts alone, and twenty-one were managed with a plate and one or two cortical struts. All of the patients were followed until fracture union or until a reoperation was done. The mean duration of follow-up was twenty-eight months for thirty-nine patients. One patient, who was noncompliant with treatment recommendations, had a failure at two months because of a fracture of the plate and graft. The primary end point of the evaluation was fracture union; secondary end points included strut-to-host bone union, the amount of final bone stock, and postoperative function. Results: Thirty-nine (98%) of the forty fractures united, and strut-to-host bone union was typically seen within the first year. There were four malunions, all of which had <10° of malalignment, and one deep infection. There was no evidence of femoral loosening in any patient. All but one of the surviving patients returned to their preoperative functional level within one year. Conclusions: Cortical onlay strut allografts act as biological bone plates, serving both a mechanical and a biological function. The use of cortical struts, either alone or in conjunction with a plate, led to a very high rate of fracture union, satisfactory alignment, and an increase in femoral bone stock at the time of short-term follow-up. Although this study did not address the potential for later allograft remodeling, our findings suggest that cortical strut grafts should be used routinely to augment fixation and healing of a periprosthetic femoral fracture.

Fresh osteochondral allografts for post-traumatic defects in the knee. A survivorship analysis

Fresh osteochondral allografts were used to repair post-traumatic osteoarticular defects in 92 knees. At the time of grafting, varus or valgus deformities were corrected by upper tibial or supracondylar femoral osteotomies. A survivorship analysis was performed in which failure was defined as the need for a revision operation or the persistence of the pre-operative symptoms. There was a 75% success rate at five years, 64% at ten years and 63% at 14 years. The failure rate was higher for bipolar grafts than for unipolar and the results in patients over the age of 60 years were poor. The outcome did not depend on the sex of the patient and the results of allografts in the medial and lateral compartments of the knee were similar. Careful patient selection, correction of joint malalignment by osteotomy, and rigid fixation of the graft are all mandatory requirements for success. We recommend this method for the treatment of post-traumatic osteochondral defects in the knees of relatively young and active patients.

Long-term followup of fresh femoral osteochondral allografts for posttraumatic knee defects.

Fresh osteochondral allografts were used to repair articular defects in the distal femur in 72 patients. Sixty patients were available for long-term followup (mean, 10 years) to determine graft survivorship and patient outcomes using a modified Hospital for Special Surgery score. Twelve of 60 grafts have failed with three having graft removal alone and nine being converted to total knee replacement. Kaplan-Meier survivorship analysis showed 85% graft survival at 10 years and 74% survival at 15 years. Patients with surviving grafts had good function, with a mean Hospital for Special Surgery score of 83 points at 10 years followup. Ten patients (17%) required meniscal transplantation whereas 41 (68%) required realignment osteotomy done simultaneously with the osteochondral allograft. Patients requiring meniscal transplantation, limb realignment, or both, had equally good outcomes at 10 years as those who underwent osteochondral transplantation alone. Likewise, transplantation to the medial or the lateral condyle had no bearing on long-term outcomes. Radiographs were available for 38 patients. These radiographs showed that 18 (48%) patients had no or mild arthritis, 10 (26%) had moderate, and 10 (26%) had severe arthritis. Late osteoarthritic degeneration as seen on radiographs was associated with outcomes, with patients with more severe arthritis having lower Hospital for Special Surgery scores. The authors think that osteochondral allograft transplantation is a valuable treatment option in patients with large osteochondral defects in the distal femoral articular surface.

Revision of the Acetabular Component of a Total Hip Arthroplasty with a Massive Structural Allograft. Study with a Minimum Five-Year Follow-up*

The results of the placement of a massive structural acetabular allograft in conjunction with a revision total hip arthroplasty in thirty-two patients (thirty-three hips) were evaluated at a minimum of five years. The graft supported more than 50 per cent of the cup in all of the patients. The goals of a revision operation in a hip that has massive loss of bone are to provide support for the cup, to approximate the normal anatomy, to restore the length of the lower limb, and to restore bone stock should a future revision be necessary. Clinical and radiographic review at an average of seven years (range, five to eleven years) after the revision revealed that eighteen hips had needed no additional operation, seven hips had needed a repeat revision but the structural allograft was intact and had been used to support the cup at the repeat revision, and eight hips had had failure of both the prosthesis and the allograft. The result was considered a clinical and radiographic success when the hip score had increased at least 20 points, the cup was stable, the allograft had united, and no additional operation was necessary. According to these criteria, the rate of success was 55 per cent (eighteen of thirty-three hips). The only factor that was found to be clinically important with respect to outcome was the method of reconstruction. Seven of the eight hips that had been reconstructed with use of a roof-reinforcement ring and a structural allograft had a successful result at an average of 7.5 years (range, five to eleven years). The findings of the present study support the use of a structural allograft in the presence of massive loss of bone in order to achieve the goals of a revision hip replacement. Because of the high rate of success with acetabular reinforcement rings, we now use this method of reconstruction whenever a massive allograft is employed on the acetabular side.

The immunogenicity of fresh and frozen allogeneic bone

Both fresh and frozen allogeneic bone elicit both acellular and humoral immune response. This response includes the development of enhancing factors which block detectable immunity and probably protect the graft from rejection. There seems to be no evidence of an alteration in immunogenicity by freezing of the graft. The importance of these observations lies in the potential technique of employing fresh viable allografts; prior freezing and tissue matching for HL-A transplantation antigens should not be necessary.

The Use of Structural Allograft for Uncontained Defects in Revision Total Knee Arthroplasty: A Minimum Five-year Review

Background: To our knowledge, the medium to long-term outcome after revision knee arthroplasty with structural allograft augmentation for reconstruction of uncontained defects has not been determined. The purpose of the present study was to assess the outcome for patients managed with such a procedure. Methods: We prospectively followed fifty patients who had fifty-two revision knee replacements with sixty-six structural grafts performed at three institutions. Twenty-nine knees (twenty-seven patients) were independently evaluated at a mean of 96.9 months (range, sixty to 189 months) by an investigator who had not been involved in the index procedure. Twelve knees (23%) had a repeat revision at a mean of 70.7 months (range, twenty-six to 157 months). The allograft was retained in two of these patients. Eleven patients died at a mean of ninety-three months (range, sixty-one to 128 months) after the procedure; the structural allograft and implants were intact, and the patients were not awaiting revision at the time of death. Results: Clinical evaluation revealed that the mean modified Hospital for Special Surgery knee score had improved from 32.5 points preoperatively to 75.6 points at the time of the review and the mean range of motion had increased from 60.5° preoperatively to 88.6°. Failure was defined as an increase of less than 20 points in the modified Hospital for Special Surgery knee score at the time of the review or the need for an additional operation related to the allograft. Thirteen knee replacements failed, yielding a 75% success rate. Five knees had graft resorption, resulting in implant loosening. Four knee replacements failed because of infection, and two knees had nonunion between the host bone and the allograft. Two knees (one patient) did not have a 20-point improvement in the knee score. The survival rate of the allografts was 72% (95% confidence interval, 69% to 75%) at ten years. On radiographic analysis, none of the surviving grafts had severe resorption, one had moderate resorption, and two had mild resorption. One knee had a loose tibial component, and three knees had nonprogressive tibial radiolucent lines. All four knees were asymptomatic. Conclusions: Our results demonstrate that allografts used in revision knee replacement in patients with the difficult problem of massive bone loss have an encouraging medium-term rate of survival.

Articular cartilage transplantation

This report describes the biopsy findings in four of 30 patients treated with cadaver osteochondral shell allografts for osteoarthritis in the knee. This study demonstrates that graft cartilage cells can survive in excess of 25 months, and that host bone can completely replace graft bone by creeping substitution. An inflammatory reaction in synovium and bone marrow was found in only one of four cases. Graft failure was related to prolonged down time of donor cartilage in one case and mechanical factors related to osteoarthritis in the apposing femoral surface in other cases. The clinical success of these grafts is attributed to the prolonged viability of cartilage cells, the capacity of host bone to join graft cartilage without histologic reaction, and the hosts immunologic tolerance, which obviates the need for immunosuppressive therapy.