Pupose: The purpose of this study was to analyze the outcome of proximal tibia osteoarticular allografts after tumor resections.

Material amd Methods: We performed a retrospective study over 58 patients in which a proximal tibia allograft reconstruction was undertaken. All patients were followed for a minimum of 5 years and allografts survival from the date of implantation to the date of revision or the time of the latest follow-up was determined with the use of the Kaplan-Meier method. In all patients, the patellar tendon from the host was reattached by suturing to overlapped donor flaps. Patients were clinically evaluated with the MSTS score system.

Results: The global rate of allograft survival was 65% +/− 12% (+/− 2 SE) at five and ten years, with no significant difference between patients who received chemotherapy and those who did not. Allografts needed to be removed in twenty patients due to 12 infection, 4 local recurrences and 4 fractures. Active knee extension was restored in all patients with an average functional score of 26.3 points.

Discussion: Survival analysis showed that 65% of proximal tibia osteoarticular allograft reconstructions remain stable at five and ten years. Patellar tendon reconstruction with allogeneic tissue in proximal tibia allograft restores active knee extension with an excellent functional result. Despite the incidence of complications, proximal tibia osteoarticular allografts continue to be a very valuable reconstructive procedure for large defects after resection of bone tumors.

Introduction: Osteoarticular allograft represents a reliable option for distal femur reconstruction. The purpose of this study was to describe the technical details and results of distal femur tumor resection and reconstruction with an osteoarticular allograft.

Material and Methods: One hundred and twenty-two patients who received an osteoarticular allograft after distal femur resection were reviewed, with a mean follow-up of 7 years. Key points for successful fixation are allograft selection, absolute stability and satisfactory soft-tissue reconstruction at the time of surgery that allows aggressive rehabilitation. Survival of the allograft was estimated with the Kaplan-Meier method. Functional and radiographic results were documented according to the Musculoskeletal Tumor Society scoring system at the time of the latest follow-up.

Results: Three patients were lost to follow and twenty-three patients died for tumor related reasons without allograft failure. In the remaining 96 allografts, eighteen allografts failed due to 7 infections, 7 local recurrences, 1 massive resorption and 3 fractures. Overall allograft survival was 82% +/− 7.6% (+/− 2 SE) at five and ten years. Those patients who preserved the original allograft had an average functional score of 27 points and a mean radiographic score of 89%, which represents a good and excellent functional and radiographic result.

Discussion and conclusion: Osteoarticular allograft is a successful procedure for reconstruction of the distal femur. Adequate preoperative planning, careful surgical technique and aggressive rehabilitation lead to excellent function and low complication rate.

Introduction: Unicompartmental osteoarticular defects of the knee are challenging due to demands of stability and function of this weight-bearing joint. Prostheses reconstruction often requires sacrificing the uninvolved compartment. Osteoarticular allograft reconstruction can restore the anatomy, and allows reattaching soft tissue structures such as meniscus and ligaments from the host. The purpose of this study was to perform a survival analysis of unicompartimental osteoarticular allografts of the knee and evaluate their complications.

Material and Methods: Forty unicompartmental osteo-articular allograft of the knee performed in 38 patients during the period 1962–2001, were followed for a mean of 11 years. In 36 patients, the bone defect was created by the resection of a tumor (33 giant cell tumors, 1 osteogenic sarcoma, 1 chondrosarcoma and 1 malignant fibrous histiocytoma) and in the remaining two by an open fracture. Twenty nine transplants were located at the femur that includes 11 medial and 18 lateral condyles. Eleven transplants were located at the tibia, including 4 medial and 7 lateral tibial plateaus. According to the reconstructed compartment, host meniscus and ligaments were reattached to the graft. Rigid internal fixation with plates and screws were used in each patient. Allografts survival from the date of implantation to the date of revision or the time of the latest follow-up was determined with the use of the Kaplan-Meier method. Complications as local recurrence, fracture, articular collapse and infection were analyzed.

Results: The global rate of allograft survival was 85% at five years. There were 8 complications in 6 patients: 2 local recurrences, 2 infections, 1 fracture, 1 massive resorption and 2 articular collapses. In 6 patients the allograft was removed and they were considered as failures. All these patients required a second allograft that included 2 unicompartmental and 4 bicompartimental reconstructions. The two patients with articular collapses required a regular total knee resurfacing prosthesis.

Discussion: Although the incidence of reoperations due to allograft complications may be high, the allograft survivor rate at five years was 85%. Unicondylar allografts, appear to be an alternative in those situations in which the massive osteoarticular bone loss to be reconstructed, is limited to one knee compartment.

Six massive femoral allografts followed up for 22 to 36 years are described. Three were intercalary, two were osteoarticular and one was a total femoral replacement. Their functional rating according to the Musculoskeletal Tumor Society System (Enneking 1987) averaged 82% (56 to 100). The radiographic score averaged 75% (48 to 100). Four allografts had suffered fractures, but three of these had later united to give good final scores. Our study shows that massive femoral allografts can function well for as long as 36 years.

In vitro studies on isolated bone cells were undertaken to investigate the presence of transplantation (histocompatibility) antigens. Bone cells were cultured with allogeneic lymphocytes and exposed to cytotoxic sera containing antibodies against transplantation antigens, to determine their antigenic profile. Preliminary results suggest that bone cells may not express lymphocyte stimulating antigens in an active form, at least after the isolation procedure performed. On the other hand, bone cells were killed by cytotoxic antibodies in a specific way, providing evidence for the presence of serologically defined (SD) transplantation antigens on the cell surface. Additional studies with absorbed sera suggest "sharing" of histocompatibility antigens between bone cells and lymphocytes. The relevance of the surface antigens of bone cells to clinical fields such as bone allotransplantation, susceptibility to various orthopaedic diseases and skeletal sarcomata is discussed.

1. Primary reticulum-cell sarcoma of bone arises from the reticulo-histiocytic elements of bone marrow.

2. The authors have studied ten cases of primary reticulum-cell sarcoma of bone, and have compared the clinical, pathological and radiographic features with those of thirty-five cases of Ewing's sarcoma.

3. In their microscopic studies Hortega's staining techniques were used in addition to orthodox methods.

4. There are histological differences between a reticulum-cell sarcoma and Ewing's sarcoma.

5. Certain clinical and radiographic features help the differentiation between the two tumours.

6. The progress and treatment of the reticulum-cell sarcoma are reviewed in detail.