Naturally occurring extracellular matrix as a scaffold for musculoskeletal repair

The use of naturally occurring extracellular matrix materials as scaffolds for the repair and regeneration of tissues is receiving increased attention. The present study evaluates the use of the extracellular matrix derived from porcine small intestinal submucosa as a scaffold for anterior cruciate ligament replacement in a goat model. Sixty healthy adult female goats were divided into two equal groups of 30 each. The right anterior cruciate ligament of each goat was removed surgically and replaced with either a patellar tendon autograft or a small intestinal submucosa anterior cruciate ligament scaffold. Three animals from each group were sacrificed at 6 weeks, 3 months, 6 months, and 1 year after surgery and grafts were harvested for histopathologic examination. Six animals from each group were sacrificed immediately after surgery, 3 months, and 1 year after surgery and the grafts were harvested for biomechanical testing. There was no evidence for an adverse clinical response to the xenogeneic small intestinal submucosa scaffold. Anterior drawer values were not different between the two groups at any point. The failure force of the patellar tendon autograft increased from 253 N at Time 0 to 879 N at 12 months. The failure force for the small intestinal submucosa repair device was 721 N at Time 0, decreased to 293 N at 3 months, followed by an increase to 706 N at 12 months. Histopathologic analysis showed a mixed inflammatory cell presence within the small intestinal submucosa scaffold including macrophages and lymphocytes in the early months after surgery. The inflammatory cells disappeared in the later stages of remodeling and the histologic appearance of the small intestinal submucosa remodeled grafts and the patellar tendon autografts were indistinguishable at 12 months. Xenogeneic small intestinal submucosa holds promise as a resorbable bioscaffold for anterior cruciate ligament repair in the goat model.

Anterior cruciate ligament reconstruction using bone-patellar tendon-bone allografts. A biological and biomechanical evaluation in goats

Twenty-eight goats underwent ACL reconstruction with freeze-dried bone-patellar tendon-bone allografts in one knee, the opposite knee serving as a control. One group of 16 knees was evaluated, in groups of four, at 6, 12, 26, and 52 weeks by histologic and vascular injection techniques. The other group of 12 knees was evaluated in two groups of six at 26 and 52 weeks by morphological and biomechanical techniques of analysis. Within the first 12 weeks these allografts were revascularized; in the first 26 weeks they had matured to resemble normal connective tissue. Graft stiffness was 29% of the control value and maximum force to failure was 43% of the control value. The results of this study indicated that freeze-dried bone-patellar tendon-bone allografts are biomechanically and biologically similar to patellar tendon autografts.

Acute increase in lateral bending of the canine lumbar disc following chymopapain injection

Twenty-four lumbar discs in six adult beagle dogs were injected with either 0.1 ml CP (ChymodiactinR) (200 U) (12 discs) or 0.1 ml saline (12 discs) under direct vision at laparotomy. All animals were killed 1 hour later; the lumbar spine was immediately excised en bloc and frozen until biomechanical testing. After overnight thawing, test specimens were prepared and consisted of a disc and half a vertebral body on each side. The posterior elements were discarded. Each motion segment was mounted on a testing plate, with bone cement used for fixation. Lateral bending of the motion segment was tested as an analog to the motion of a disc during correction of a scoliotic spine with a distraction force. Lateral bending forces of 2 kg and 4 kg were applied for 30 minutes each. Lateral bending, creep, and residual deformity (in degrees) were recorded. CP injected disc showed an acute increase in lateral bending of 28% and 26%, respectively (2-kg and 4-kg loads) (P less than 0.001). In addition, CP injected discs showed a 25% increase in their residual angular deformity compared with the control discs (P less than 0.001). No significant changes were noted in creep values between CP and saline injected discs. This study demonstrates a significant acute increase of 28% and 26% in lateral bending of the canine disc following enzyme injection.

Treatment of fractures of the tibial tuberosity in the dog

Of 27 dogs with fractures of the tibial tuberosity, 24 were treated by various methods of open reduction. Follow-up examination was obtained in 21 cases, and it was found that all but one fracture healed in 8 weeks. Tension band wiring and single interfragmentary screws were most commonly used; healing was similar in both groups.