Clinical and MRI evaluation of meniscal tears repaired with bioabsorbable arrows.

BACKGROUND AND AIMS: Excision of meniscal tissue has been shown to increase the risk of degenerative changes of the knee joint. Whenever possible, meniscus repair has become the procedure of choice for treatment of meniscal tears. MATERIALS AND METHODS: The present retrospective study evaluated the healing results of 77 meniscal ruptures treated with the an all-inside technique (Biofix meniscus arrow). The study group consisted of 73 patients with 77 longitudinal, vertical meniscal ruptures treated at Helsinki University Hospital between the beginning of January 1997 and the end of March 2001. The patients who had not received secondary surgery for failed repair during the follow-up period were examined clinically and with MRI. RESULTS: Fifty-one out of 77 meniscal ruptures (66%) healed clinically. In repairs performed in conjunction with ligament reconstruction the healing rate was higher (79%) than in the isolated tears (56%). The poorest results were seen in the very long vertical tears with luxation of the meniscus (38% healing rate). CONCLUSIONS: Bioabsorbable arrows offer a good alternative for treatment of meniscal ruptures, but the arrows alone do not seem to be sufficient to provide a reliable long-lasting result in the repair of very unstable meniscal ruptures.

Inability of transforming growth factor-beta 1, combined with a bioabsorbable polymer paste, to promote healing of bone defects in the rat distal femur.

The ability of transforming growth factor-beta 1 (TGF-beta 1) to promote bone formation suggests that it may have potential as a therapeutic agent in bone defects. However, there still exists a need for an effective method of delivering TGF-beta 1 to the site of an osseous defect. In the present study, TGF-beta 1 was embedded in a bioabsorbable polymer paste (a blend of an L-lactide oligomer and a copolymer of epsilon-caprolactone and DL-lactide). The release of TGF-beta 1 from the polymer paste was examined in vitro with an enzyme-linked immunosorbent assay, which showed sustained release of active TGF-beta 1 over a 7-day period. Further, the polymer paste was used to fill a bone defect in the rat distal femur. The amount of TGF-beta 1 per rat was 50 micrograms, while in a control group we used an identical polymer paste without the growth factor. After a follow-up of 1 week and 3 weeks, the femurs were examined radiographically, histologically, histomorphometrically, microradiographically, and were also used for tetracycline-labeling studies. TGF-beta 1 did not enhance healing of the bone defect. A combination of growth factors would probably be a more potent osteoinductor than TGF-beta 1 alone.

Combining transforming growth factor-beta(1) to a bioabsorbable self-reinforced polylactide pin for osteotomy healing: an experimental study on rats.

The effect of a bioabsorbable pin containing transforming growth factor-beta(1) on fracture healing was studied in a rat model. The growth factor was mixed into a bioabsorbable polymer paste (a blend of an l-lactic acid oligomer and a copolymer of epsilon-caprolactone and dl-lactide) that was used to fill the grooves of a self-reinforced fracture fixation pin made of a poly-ld-lactic acid copolymer. In an in vitro assay, sustained release of the growth factor from the pins over a 7-day period was demonstrated. A distal femoral osteotomy was made in 60 rats and stabilized with the fracture fixation pin in 48 of them; In the remaining 12 rats, no fixation was performed. The pin used in the study group contained either 5 microg (15 rats) or 50 microg (15 rats) of the growth factor, while in a control group of 18 rats an identical pin without the growth factor was used. After a follow-up of 1, 3, or 6 weeks, the femurs were examined radiographically, histologically, histomorphometrically, and microradiographically, and also used in tetracycline labeling studies. Faster callus formation was evident in the growth factor-treated rats but no acceleration in the healing of the osteotomy was detected.

Polylactide pin with transforming growth factor beta 1 in delayed osteotomy fixation.

The effect of an absorbable pin containing transforming growth factor beta 1 on fracture healing was studied in a rat model of delayed osteotomy fixation. Transforming growth factor beta 1 was mixed into a blend of L-lactide oligomer and a copolymer of epsilon-caprolactone and DL-lactide that was placed in the grooves of a self reinforced fracture fixation pin made of poly-LD-lactic acid copolymer. A distal femoral osteotomy was made in 54 rats and left untreated. A week later surgery was performed to fix the osteotomy with a fracture fixation pin in 48 rats. In the remaining six rats no fixation was performed. The pin that was used in the study group contained either 5 micrograms (15 rats) or 50 micrograms (15 rats) of the growth factor, while in the control group of 18 rats, an identical pin without growth factor was used. The femurs were examined radiographically, histologically, histomorphometrically, and microradiographically. Tetracycline labeling studies were used after a followup of 1, 3, and 6 weeks. Faster callus formation in the transforming growth factor beta 1 treated animals but no acceleration in the healing of the osteotomy is reported. The addition of bone growth factors to bioabsorbable fracture fixation materials may enhance bone healing.