Introduction: Autologous chondrocyte implantation (ACI) has been developed in order to repair cartilage successfully. Experimental models are based on osteochondral defects with potentially triphasic chondrogenic system: periosteal flaps, bone marrow cells and transplanted chondrogenic cells. All these three have chondrogenic activity so it is difficult to determinate the role of the implanted cells unless appropriate control is set up.

The purpose of this study is to determinate if the inoculation of chondrocytes under periosteal flaps does improve the chondrogenic potential of periosteal flaps.

MATERIALS AND Methods: 10 New Zealand rabbits, 8 months old were used. Right knees served as study group (ACI Group; N5: Chondrocytes + Periosteal Flap) – (Fibroblast Group: N5 Fibroblast + Periosteal Flap) and left knees as control group (N: 10: osteochondral defect alone). During the first procedure dermal fibroblast cells were isolated from skin biopsy and chondrocytes were isolated from the medial femoral condyle as a full thickness of the right and left knee were done. Chondrocytes and dermal fibroblasts cells were incubated for 4 weeks. Then they were implanted under periostel flap according to study group.

Chondrocyte and Fibroblast Implantation:

A parapatellar incision was performed on both knees. Defect was cleaned and on study group the periosteum taken from the tibia was sutured leaving one edge free to inoculate the chondrocytes or fibroblast according to group using a needle Then the defect was closed using fibrin glue. The animals were euthanatized 8 months postoperative.

Analysis: Specimens were evaluated using Hematoxylin and Eosin. Safranine and inmunohistochemistry for Collagen Type 2 using the ICRS score system.

Statistical Analysis: T student, Fisher and confidence interval were used. A p value < 0,05 was considered significant.

Results: Control non treated group presented a histological score grade mean IV (95% CI: 44–97)

The ACI group showed a tissue type means II (ICRS) (95% CI: 28–99%) Collagen type 2 was evident only in the deep layers. The fibroblast group did show a reparative tissue, tissue type mean II (95% CI: 28–99%) Collagen type 2 was evident in deep layers

DISCUSSION: According to this study the inoculation of chondrocytes under periosteal flaps does not improve significally the chondrogenic potential of periosteal flaps.(p: 0,77). Comparing the same procedure with chondrogenic and non chondrogenic cell lines could determinate the role of different chondrogenic components (periosteum and chondrocytes). Probably the chondrogenic capacity of the periosteum is sufficient to stimulate a reparative tissue. However none of these procedures could establish an adult normal cartilage hyaline tissue.

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.

Purpose of the study: The objective of this work was to analyze outcome in a series of patients with bone anomalies after failed knee arthroplasty who were treated in the same institution with revision prosthesis with use of fragmented and structured bone grafts.

Material and methods: Between April 1994 and June 2004, a total of 515 knee arthroplasties were performed at the Italian hospital of Buenos Aires. Among these, 27 were revisions after failure of a primary arthroplasty. Two patients (follow-up less than one year) were excluded from the analysis. Among the 25 patients analyzed, eight were men and 17 women, mean age 67 years (range 41–87). Minimum follow-up was one year, mean 3.5 years, range 3–9 years. The cause of primary arthoplasty failure was aseptic loosening for ten knees, prosthetic infection in eleven, and pain in three and periprosthetic fracture in one. Fragmented or structured allografts were used for reconstruction in 15 patients. Reconstruction concerned the femur or the tibia after removal of the primary prosthesis. For twelve patients, a fragmented allograft was impacted and for three a combined fragmented-structured allograft was used. For 21 reconstructions, the revision prosthesis had intramedul-lary femoral and tibial stems and for 15, complementary elements were added to the prosthetic components on the femoral piece for three, on the tibial piece for four and on both for eight.

Conclusion: Use of fragmented and structured allografts combined with complementary elements offers a valid alternative for reconstruction of bone stock loss after failed primary knee arthroplasty.

Purpose of the study: High quality knee stability and function after unicompartmental reconstruction is a considerable surgical challenge. Occasionally, the healthy compartment has to be sacrificed to achieve prosthetic reconstruction. Osteoarticular reconstructions using allografts enable restoration of the anatomic configuration and reinsertion of the articular structures (menisci) and periarticular ligaments. The purpose of this study was to analyze survival of unicompartmental osteoarticu-lar allografts of the knee and to assess complications.

Material and methods: A series of 40 unicompartmental osteoarticular allografts of the knee joint were performed from 1962 to 2001 in 38 patients followed for ten years on average (range 2–35 years). Reconstruction was performed after tumor resection in 36 patients (33 giant-cell tumors, 1 osteogenic sarcoma, 1 chondrosarcoma, 1 malignant fibrohistocytome) and after open fracture in two. The procedure involved a femoral allograft in 29 knees (medial for 11 and lateral for 18), and a tibial graft in 11 (medial for 4 and lateral for 7). Menisci and ligaments were attached to the allograft depending on the configuration of the reconstruction. A rigid screw plate internal fixation was used in all cases. The Kaplan-Meier survival was plotted from implantation to revision or last follow-up. Complications (local recurrence, fracture, joint collapse, infection) were analyzed.

Results: The overall survival at five years was 85%. There were eight complications in six patients: local recurrence (n=2), infection (n=2), fracture (n=1), massive resorption and joint collapse (n=1). Complications were considered as failures and a second reconstruction with a second allograft (two unicompartmental and four bicompartmental allografts) or a prosthetic allograft (for two joint collapse cases) were performed.

Discussion: Despite a high rate of revision for complications, five-year survival of unicompartmental allografts was 85%. This procedure appears to be a useful solution for massive loss of bone and joint stock limited to a single compartment.

Purpose of the study: The purpose of this study was to compare two reconstruction procedures in terms of efficacy for tumor eradiation, reconstruction complications, and potential joint consequences.

Material and methods: This retrospective study included 43 patients with a giant-cell tumor located in the knee. Patients were treated by curettage combined with phenolization. Mean follow-up was seven years. Bone defects were filled with cement in 22 patients and with a fragmented allograft in 21. The reconstruction and potential joint degradation were assessed on standard x-rays obtained in the two groups.

Results: There were four cases of local recurrence (9%), two in each group. Three patients in the cement group required revision because of joint degradation in two and cement intrusion into the joint in the third. In the allograft group, two patients developed complications (fracture and massive resorption). Plan x-rays revealed joint deterioration in 10/17 patients with an allograft. The difference was significant (p=0.019).

Conclusion: The rate of local recurrence and complications after reconstruction requiring a revision procedure was not significantly different in the two groups. There was however a significantly greater radiographic degradation in patients with a bone defect filled with cement compared with those with a defect filled with a fragmented allograft.

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.