Method of performing anterior cruciate ligament reconstruction using biodegradable interference screw

Abstract

A method of replacing an ACL with a graft. The method provides for the drilling bone tunnels in a femur and a tibia. A replacement graft is provided having first and second ends. A biodegradable composite screw is provided. The screw is made from a biodegradable polymer and a bioceramic or a bioglass. At least one end of the graft is secured in a bone tunnel using the biodegradable composite screw.

Description

TECHNICAL FIELD [0001] The field of art to which this invention relates is surgical procedures for the repair of an anterior cruciate ligament, more specifically, a surgical procedure for affixing an anterior cruciate ligament graft into a bone using a biodegradable interference screw. BACKGROUND OF THE INVENTION [0002] The knee joint is one of the strongest joints in the body because of the powerful ligaments that bind the femur and tibia together. Although the structure of the knee provides one of the strongest joints of the body, the knee may be one of the most frequently injured joints, e.g., athletes frequently stress and tear knee ligaments. The large number of ligament injuries has given rise to considerable innovative surgical procedures and devices for replacing and reconstructing torn or dislocated ligaments, typically involving grafting autografts, allografts, or a synthetic construct, to the site of a torn or dislocated ligament. For example, the replacement of an anteri...

AI Technical Summary

Benefits of technology

"The present invention provides a novel method for replacing a ruptured or injured anterior cruciate ligament in the knee using a graft and a biodegradable interference screw. The interference screw is made from a copolymer of poly (lactic acid) and poly(glycolic acid) and a bioceramic. The screw is inserted into the femoral bone tunnel and rotated to secure the graft in place. The technical effect of this invention is to provide a reliable and effective method for repairing a ruptured or injured anterior cruciate ligament."

Problems solved by technology

Although the structure of the knee provides one of the strongest joints of the body, the knee may be one of the most frequently injured joints, e.g., athletes frequently stress and tear knee ligaments.

A ruptured or damaged ACL typically results in serious symptoms such as knee instability resulting in diminished ability to perform high level or recreational sports, or in some cases daily activities relating to motility.

Although the use of knee braces may alleviate some of these symptoms, the potential long term effects of a damaged ACL include meniscal damage and articular cartilage damage.

Although repair would be a preferred procedure, it is not typically possible since the end of the torn ACL is typically not of sufficient length to reattach successfully.

One potential disadvantage of such screws is that once healing is complete, the screw remains in the bone.

An additional disadvantage of a metal screw is that in the event of a subsequent rupture or tear of the graft, it may be necessary to remove the metal screw from the bone site.

The enlarged heads on such screws can protrude from the bone tunnel and can cause chronic irritation and inflammation of surrounding body tissue.

Permanent metallic medical screws in movable joints can, in certain instances, cause abrading of ligaments during normal motion of the joint.

Screws occasionally back out after insertion, protruding into surrounding tissue and causing discomfort.

Furthermore, permanent metallic screws and fixation devices may shield the bone from beneficial stresses after healing.

Under some conditions, the stress shielding which results from the long term use of metal bone fixation devices can lead to osteoporosis.

However, it is known that screws made from polylactic acid tend to maintain their structural integrity for very long periods of time thereby preventing the desired bone in growth.

The problem often associated with these quicker absorbing polymers or copolymers is that the bone regeneration may proceed at a much slower rate than the rate of resorption, resulting in premature mechanical failure of the screw and a resulting pull out of the graft end from the femoral tunnel.

Some of the absorbable interference screws of the prior art may take several years to absorb, and may result in a fibrous tissue mass or cyst being left behind, not bone.

This lack of bone in-growth may create fixation problems if the ACL is torn again, necessitating a new graft replacement.

In addition, if the screw absorbs too slowly, the screw will need to be removed in the event of a subsequent failure of the graft.

Images