Search

Copyright © Taylor & Francis 2004. ISSN 0001–6470. Printed in Sweden – all rights reserved. A 43-year-old man presented with persistent pain on the medial side of his left knee, 1 year after a bone-patellar tendon-bone autograft ACL reconstruction. Besides a dysfunctional ACL, earlier arthroscopy had already revealed a focal full-thickness chondral lesion (25 × 12 mm) of the medial femoral condyle (Figure 1A) and mild degenerative changes in the lateral compartment of the knee. The patient was offered a mosaicplasty of the medial femoral condyle. After a medial arthrotomy of the knee, 3 cylindrical osteochondral plugs (8 mm diameter) were harvested from the lateral throchlea (donor site) and transplanted to the chondral defect in the medial femoral defect (recipient site), using the mosaicplasty technique (Hangody et al. 1998, Bobic 1999, Hangody and Fules 2003, Horas et al. 2003). The donor site defects were each fi lled with a press-fi tted cylindrical osteo-periosteal plug obtained from the proximal tibia. It was hypothesized that these plugs would enhance healing of the subchondral bone and that the covering periosteum would enhance resurfacing of the donor site defects with fi brocartilagenous tissue. Initially, the patient’s symptoms clearly improved and a postoperative MRI showed restoration of the joint surface at the original chondral lesion in the medial condyle 3 months after surgery (Figure 1B). The 3 transplanted osteochondral plugs were still clearly visible in the subchondral bone, with signs of osseous integration. One plug appeared to have been placed rather too deeply, as seen from the step-off in the subchondral bone (Figure 1B, 2A). At the lateral aspect of the trochlea, the 3 donor site defects were also still clearly visible (Figure 1C). The osteo-periosteal plugs from the proximal tibia appeared to have remained in situ and some resurfacing of the defects had occurred. After 3 years the knee became symptomatic again, with pain and swelling. Radiographic evaluation revealed mild degenerative changes (Figure 1D). Conservative treatment was not accepted and a total knee arthroplasty was performed. This procedure eventually provided good-quality retrieval specimens for histological evaluation of a mosaicplasty.

Contains fulltext : 95878.pdf (Publisher’s version ) (Open Access) PURPOSE: The aim of this study was to evaluate subsidence tendency, surface congruency, chondrocyte survival and plug incorporation after osteochondral transplantation in an animal model. The potential benefit of precise seating of the transplanted osteochondral plug on the recipient subchondral host bone ('bottoming') on these parameters was assessed in particular. METHODS: In 18 goats, two osteochondral autografts were harvested from the trochlea of the ipsilateral knee joint and inserted press-fit in a standardized articular cartilage defect in the medial femoral condyle. In half of the goats, the transplanted plugs were matched exactly to the depth of the recipient hole (bottomed plugs; n = 9), whereas in the other half of the goats, a gap of 2 mm was left between the plugs and the recipient bottom (unbottomed plugs; n = 9). After 6 weeks, all transplants were evaluated on gross morphology, subsidence, histology, and chondrocyte vitality. RESULTS: The macroscopic morphology scored significantly higher for surface congruency in bottomed plugs as compared to unbottomed reconstructions (P = 0.04). However, no differences in histological subsidence scoring between bottomed and unbottomed plugs were found. The transplanted articular cartilage of both bottomed and unbottomed plugs was vital. Only at the edges some matrix destaining, chondrocyte death and cluster formation was observed. At the subchondral bone level, active remodeling occurred, whereas integration at the cartilaginous surface of the osteochondral plugs failed to occur. Subchondral cysts were found in both groups. CONCLUSIONS: In this animal model, subsidence tendency was significantly lower after 'bottomed' versus 'unbottomed' osteochondral transplants on gross appearance, whereas for histological scoring no significant differences were encountered. Since the clinical outcome may be negatively influenced by subsidence, the use of 'bottomed' grafts is recommended for osteochondral transplantation in patients.

To evaluate the short-term outcome of osteochondritis dissecans (OCD) treated with mosaic osteochondral autograft transplantation (OAT), 7 male patients (mean age 33.4) with 8 OCD lesions on the lateral border of the medial femoral condyle were prospectively followed. Patients were evaluated by the International Knee Documention Committee (IKDC) score and the Knee injury and Osteoarthritis Outcome Score (KOOS) questionnaires preoperatively, at 6 months and 1 year after surgery. MRI evaluation using the modified Sanders score was performed at 1-year follow-up. The IKDC subjective score and all subscales of the KOOS improved significantly. MRI evaluation showed good surface congruency, no oedema or protuberance of the osteocartilaginous cylinders, good similarity of cartilage thickness and a non-complete osseous integration. With the small numbers of patients available, no correlation could be found between MRI findings, percentage of defect coverage and patient satisfaction. Mosaic OAT appeared in this study as a valid treatment option in selected cartilage defects. OCD lesions improved significantly following osteochondral transplantation. The limitations of this technique are the number and size of the plugs needed to repair the defect. Future research should focus on identifying the appropriate choice of operative treatment for well defined subtypes of articular cartilage lesions, rather than searching for one superior technique for all.

Contains fulltext : 70643.pdf (Publisher’s version ) (Open Access) Osteochondral transplantation is a successful treatment for full-thickness cartilage defects, which without treatment would lead to early osteoarthritis. Restoration of surface congruency and stability of the reconstruction may be jeopardized by early mobilization. To investigate the biomechanical effectiveness of osteochondral transplantation, we performed a standardized osteochondral transplantation in eight intact human cadaver knees, using three cylindrical plugs on a full-thickness cartilage defect, bottomed on one condyle, unbottomed on the contralateral condyle. Surface pressure measurements with Tekscan pressure transducers were performed after five conditions. In the presence of a defect the border contact pressure of the articular cartilage defect significantly increased to 192% as compared to the initially intact joint surface. This was partially restored with osteochondral transplantation (mosaicplasty), as the rim stress subsequently decreased to 135% of the preoperative value. Following weight bearing motion two out of eight unbottomed mosaicplasties showed subsidence of the plugs according to Tekscan measurements. This study demonstrates that a three-plug mosaicplasty is effective in restoring the increased border contact pressure of a cartilage defect, which may postpone the development of early osteoarthritis. Unbottomed mosaicplasties may be more susceptible for subsidence below flush level after (unintended) weight bearing motion.

Contains fulltext : 50123.pdf (Publisher’s version ) (Open Access) BACKGROUND: Osteochondral autologous transplantation is used for the treatment of full-thickness articular cartilage lesions of a joint. Press-fit stability is an important factor for good survival of the transplanted plugs. MATERIAL AND METHODS: 36 plugs of three different lengths were transplanted in fresh-frozen human knees. On one condyle, 3 plugs were exactly matched to the depth of the recipient site ("bottomed" plugs) and on the opposite condyle 3 plugs were 5 mm shorter than the depth of the recipient site ("unbottomed" plugs). Plugs were left protruding and then pushed in until flush, and then to 2 mm below flush level, using a loading apparatus. RESULTS: Longer plugs needed higher forces to begin displacement. At flush level, bottomed plugs needed significantly higher forces than unbottomed plugs to become displaced below flush level (mean forces of 404 N and 131 N, respectively). Shorter bottomed plugs required higher forces than longer bottomed ones. INTERPRETATION: Bottomed plugs generally provide much more stability than unbottomed ones. Short bottomed plugs are more stable than long bottomed plugs. Thus, in clinical practice it is advisable to use short bottomed plugs. If, however, unbottomed plugs are still chosen, the longer the plug the higher the resulting stability will be because of higher frictional forces.