The following two papers (Nos. 108 and 116) were omitted from the Proceedings of the Orthopaedic Research Society (1975 Annual Meeting) published in the July issue of The Journal. They are printed here to complete the record.
Biomechanical and Ultrastructural Changes in Ligaments and Tendons After Local Corticosteroid Injections. DR. FRANK R. NOYES*, DR. NOEL S. NUSSBAUM, DR. PETER J. TORVIK, and DR. SHELDON COOPER studied the strength, functional capacity, and histological properties of ligament and tendon after the local administration of methylprednisolone acetate in a dose used clinically. One hundred and ten wild adult rhesus monkeys, killed six, fifteen, and fifty-two weeks after intra-articular (knee) or direct intraligament injection, provided 181 anterior cruciate bone-ligament-bone specimens for biomechanical and histological analysis. Mechanical properties were determined by testing in tension to failure under high strain-rate conditions. The results were dependent on route, dose, and time after drug injection. After a single intracollagenous injection, there were marked decreases in ligament stiffness, failure load (27 to 39 percent), and energy absorption (27 to 43 percent), which persisted for up to fifty-two weeks. Scanningelectron microscopy showed altered fibrils and abundant corticosteroid crystals. Histological examination of both tendons and ligaments after intracollagenous injection showed death and absence of fibrocytes. After the intra-articular injections, only minimum alterations in mechanical properties of the ligament unit occurred. Mechanisms possibly responsible for the changes include antianabolic and catabolic actions. The results show that direct intracollagenous corticosteroid injections may substantially alter function and reduce strength of collagenous structures.
* Aerospace Medical Research Laboratory, Wright-Patterson Air Force Base, Ohio 45433.
Prosthetic Anterior Cruciate Ligament in the Beagle Dog. DR. R. M. RUBIN*, DR. J. L. MARSHALL, and DR. J. WANG reported that loss of the anterior cruciate ligament in Beagle dogs results in predictable arthritis which can be prevented by successful prosthetic substitution of the ligament, thus providing a practical model for evaluation of prototype prostheses. In sixteen Beagle dogs the anterior cruciate was replaced with a mesh or tape Dacron prosthesis. When the dogs were killed up to three years later, eight joints showed no arthritic changes, while arthritis developed in all joints in which the prosthesis elongated or broke—always intra-articularly at the mouth of one of the bone tunnels. Porous mesh did not provide a lattice for ligament regeneration across the joint. The results of reconstruction were inconsistent even using a single breed and the same materials. The techniques for making the drill holes had not been truly standardized. The effects of variations in placement of the prosthesis were compounded by the cutting action of the bone edges. Gait and anterior drawer sign were unreliable indicators of insufficiency of the anterior cruciate ligament in dogs.
* 535 East 70th Street, New York, N.Y. 10021.