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.

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.