Experimental evaluation of the usefulness of osteochondral allograft for articular cartilage defect

Osteochondral Lesions of the Talus Treatment With Fresh Frozen Allograft

INTRODUCTION

Symptomatic talar osteochondral lesions are about 50% refractory to conservative treatment requiring a surgical solution. In the case of large chronic lesions, the use of bone graft taken from tissue bank is an alternative that enables to fill the defect without causing donor site morbidity.

MATERIAL AND METHODS

Eight patients treated with talar osteochondral allograft in lesions greater than 20mm in diameter were analyzed - 4 males and 4 females aging 39.5 years old on average. Evaluation was performed according to AOFAS scale and VAS as well as incorporation and continuation evaluations according to CT and MRI studies. A follow-up of 46.8 months on average was done.

RESULTS

A 34.6-point improvement on average according to AOFAS. A 6.7-point pain improvement on average according to VAS. Incorporation in 100% of the cases. Two cases showed partial resorption and one case showed peri-graft lysis less than 30%. There was no collapse.

CONCLUSIONS

Fresh frozen osteochondral allografts are a viable alternative when treating large osteochondral lesions, thereby avoiding morbidity of autologous donor areas or arthrodesis procedures.

The effect of defect localization on spontaneous repair of osteochondral defects in a Gottingen minipig model: a retrospective analysis of the medial patellar groove versus the medial femoral condyle

Various animal models for experimental osteochondral defect healing have been used in orthopaedic research. Two main defect locations were chosen: the patellar groove or the central part of the medial femoral condyles (MFC). To date, it is not clear whether both locations display similar patterns in critical size osteochondral defect healing. We retrospectively analysed both locations in our minipig model hypothesizing that they show similar healing pattern. Thirty-five defects were analysed after three or 12 months. Osteochondral defects were 10 mm deep and 6.3 mm (MFC, n = 19) in diameter or 8 mm and 5.4 mm, respectively (trochlear groove [TG], n = 16). Semi-quantitative histological scoring and histomorphological evaluation were carried out. Both defect locations showed fillings of fibrous and fibrocartilage-like repair tissue. The osseous defect was closed by endochondral bone formation in the MFC. Semi-quantitative scoring did not show differences, whereas qualitative histomorphological analysis more frequently showed cartilaginous repair tissue in MFC defects. There was more frequent subchondral bone cyst formation in MFC location (P = 0.05), TG defects resulted in lower postoperative pain. Both defect localizations are suitable for studies on osteochondral healing. Since regenerating with less hyaline-like repair tissue and less subchondral cyst formation, TG is more favourable for experimental osteochondral defect healing in this model.

The fate of osteochondral grafts after autologous osteochondral transplantation: a one-year follow-up study in a minipig model

INTRODUCTION

Because articular cartilage shows little intrinsic capacity of spontaneous regeneration, a variety of treatment options are currently at use to repair cartilage damage. One of these is the autologous osteochondral transplantation (AOT). The aim of the present work was to study the histological changes during the progress of 1 year after AOT in the knee joint.

MATERIALS AND METHODS

Twelve Minipigs underwent an AOT on the medial femoral condyles of both knees using cooled diamond studded trephines with a diameter of the grafts of 4.6 mm. Three animals were sacrificed at each 2, 8, 26 and 52 weeks after the operation. The condyles were analyzed histologically and immunohistologically for collagen types I and II.

RESULTS

A successful bony incorporation was observed in all specimens. The transplant demonstrated an increasingly stable integration of the chondral matrix into the cartilage of the surrounding femoral condyle. At 52 weeks after the operations 5 of 6 condyles showed a chondral integration at least at one side of the graft. Immunohistologically all specimens showed physiological staining characteristics up to 52 weeks after operation. The quality of the chondral part of the graft showed a wide range of variations, ranging from vital tissue resembling native cartilage after 52 weeks, to severe degenerative signs beginning 2 weeks after operation and ending at 52 weeks with deep fissures fragmenting the cartilage and the complete loss of vital cells.

CONCLUSION

The press-fit technique allows a stable bony incorporation. A chondral integration of the graft seems to occur, provided that a close contact between the interfaces can be achieved. Present results demonstrate a vital cartilagenous transplant for up to 52 weeks. However, some specimens showed in part severe degenerative signs. A possible explanation is an insufficient cooling of the trephines in relation to the small diameter of the grafts used in the minipig model. The collagen network seems not to be affected for up to 52 weeks.

Dimethyl sulfoxide toxicity kinetics in intact articular cartilage

Osteochondral defects can degenerate into osteoarthritis and currently there are no good treatment alternatives available to most Orthopaedic surgeons. Osteochondral allografting can restore damaged joint surfaces but its clinical use is limited by poor access to high quality tissue. Vitrification of osteochondral tissue would allow the banking of this tissue but requires high concentrations of cryoprotective agents. This study was designed to ascertain dimethyl sulfoxide (DMSO) toxicity kinetics to chondrocytes in situ after exposure to DMSO at different temperatures recorded as a function of time. Porcine osteochondral dowels were exposed to 1, 3, 5, and 6M DMSO at 4, 22, and 37 degrees C for 0.5 min to 120 min. Chondrocyte recovery was determined by membrane integrity (Syto 13 and ethidium bromide) and mitochondrial (WST-1) assays. Results demonstrated that cell recovery was concentration, temperature and time dependent. At higher concentrations and temperatures, significant cell loss occurred within minutes. A rate constant calculated for chondrocyte death was dependent on temperature. 1 M DMSO appeared relatively non-toxic. This experiment established a method to examine systematically toxicity parameters for chondrocytes in situ and this data can be used to tailor vitrification protocols by limiting exposure temperature and time or lowering DMSO concentrations below toxic levels recorded.

Reconstruction of the distal radius facet by a free vascularized osteochondral autograft: anatomic study and report of a patient

PURPOSE

Large chondral defects of the distal radius after fractures present a reconstructive challenge. The purpose of this study was to present the anatomic findings from a cadaver of a vascularized osteochondral autograft taken from the third metatarsal appropriate for reconstructing the distal radius articular facet. A patient is presented in whom 70% of the scaphoid fossa was reconstructed with this technique.

METHODS

The base of the third metatarsal was studied in the feet of 20 cadavers. The size and shape of the cartilage were measured. Additionally vessel distribution was recorded and the diameters of vascular foramina were measured with Juch's method.

RESULTS

The base of the third metatarsal is pear shaped and is wider dorsally than plantarly. It averages 19.2 mm long on its main axis. Its cartilaginous surface is minimally concave or flat and it is slanted slightly proximal-dorsal to distal-plantar and proximal-peroneal to distal-tibial. Nutrient foramina were found in every case in the dorsum and on both sides of the proximal shaft. At least 1 nutrient vessel could be tracked back to the dorsalis pedis in every dissected specimen.

CONCLUSIONS

The anatomic features of the base of the third metatarsal make it a potential vascularized autograft to consider for osteochondral defects of the distal radius.

Stage VI: massive osteochondral defects of the talus

This article addresses very large osteochondral lesions of the talus with an osteonecrosis overlap. Six cases are discussed where lesions were deemed too large for osteochondral autograft transfer (OATS) or autologous chondrocyte transplant (ACT). These cases were treated with bulk fresh or fresh frozen matched talus allograft transplantation. The associated literature is reviewed.