Graft fixation strength with arthroscopic anterior cruciate ligament reconstruction. Two-incision rear entry technique compared with one-incision technique.

To compare the fixation strengths of two arthroscopic anterior cruciate ligament reconstruction techniques, we harvested 10-mm bone-patellar tendon-bone grafts with 25-mm bone plugs from 12 fresh-frozen cadaveric knees. One knee of each pair was fixed using Acufex instruments and the two-incision technique; one knee was fixed using Arthrotek instruments and the one-incision technique. We used cannulated 9 x 25 mm Kurosaka screws for femoral and tibial tunnel fixation. All knees were mounted on the Instron Test System and were stressed to failure by recreating a pivot shift maneuver. The one-incision technique graft fixation was significantly stronger (mean failure, 695 N) than that with the two-incision technique (mean failure, 593 N). In all one-incision technique knees, either the patellar tendon graft avulsed off a bone plug or the plug broke. In five of six two-incision technique knees, the tibia bone plug pulled out around the interference screw. Patellar tendon graft length ranges from 90 to 105 mm, and the average two-incision technique tunnel length is 120 mm. The interference screw compressed the femoral bone plug into conical bone but compressed the tibial bone plug into cancellous bone in the two-incision technique, while in the one-incision technique the bone plug was compressed into cortical bone on both sides.

The growth and phenotypic expression of human osteoblasts.

The care of patients with a skeletal deficiency currently involves the use of bone graft or a non-biologic material such as a metal or polymer. There are alternate possibilities in development which involve the growth of bone cells (osteoblasts) on degradable polymer scaffolds. These tissue engineering strategies require production of the polymeric scaffold, cellular harvest followed by either ex vivo or in vivo growth of the cells on the scaffold, and exploration of the interaction between the cell and scaffold. Research into these strategies utilizes cells from a variety of species, but clinical applications will likely require human osteoblasts. This study explores the process whereby human osteoblasts are harvested under sterile conditions during joint replacement surgery from normally discarded cancellous bone, transported from the operating room to the lab, and grown in culture. This process is feasible, and the cells express their phenotype via the production of alkaline phosphatase and collagen in culture.