Document Title: Musgrove-AJSM-Sep00

Article Title: The influence of reverse-thread screw femoral fixation on laxity measurements after anterior cruciate ligament reconstruction with hamstring tendon

Authors: Tim P. Musgrove, Lucy J. Salmon, Charles F. Burt, Leo A. Pinczewski.

Publication: The American Journal of Sports Medicine

ISSN: 03635465

Date: September-October 2000

(Figures included. Reference-denoting numbers appear in the same point size as document text.)

Volume: 28

Issue: 5

Pages: 695-699

Key Words: Knee, hamstring, tendon graft, ACL.

 

Musgrove looks at the effect of the threading direction of the interference screw, as used to anchor ACL grafts. During tightening of the screw, the graft tends to be rotated inside the femoral tunnel; for right knees, the net result is that the graft ends up at the front of the tunnel, hence ending up too loose. Using reverse-threaded screws alleviates the problem. Musgrove recommends that when right-ACL reconstruction with interference-screw anchorage is performed, a reverse-threaded screw be selected for use in the femoral tunnel. (Note that it is technically impossible for any ACL graft to perfectly replicate the natural multifascicular structure of the natural ACL; however, a well-placed, correctly-tensioned graft comes reasonably close.)

 

This document was presented at the 25th annual meeting of the AOSSM, Traverse City, Michigan, June 1999.

 

ABSTRACT

 

In arthroscopically assisted anterior cruciate ligament reconstruction using hamstring tendon graft, the graft rotates slightly as the femoral screw is inserted. Its final position tends to be in the anterior half of the tunnel in right knees, resulting in clinical laxity. To perform identical procedures on left and right knees, a reverse-thread screw was designed for femoral fixation in right knees. We prospectively studied 80 patients undergoing right-knee anterior cruciate ligament reconstruction with hamstring tendon autograft. Thirty-six patients underwent reconstruction with a standard screw and 44 underwent reconstruction with a reverse-thread screw. The same technique, performed by the same surgeon, was used on all patients. At 12 months' follow-up, the average side-to-side differences on arthrometry testing were 2.00 mm for the standard screw group and 0.95 mm for the reverse-thread screw group using a manual maximum test, and 1.66 mm and 1.00 mm, respectively, using the 20-pound test. Both differences were statistically significant. Of the standard group, 23% had a manual maximum difference of 3 mm or more, compared with 8% of the reverse-thread group. A significant difference was found between these two groups for Lachman test (77% with grade 0 for the standard group compared with 92% for the reverse group) but pivot shift and Lysholm knee score were not significantly different. The use of a reverse-thread screw for femoral fixation in right-knee anterior cruciate ligament reconstructions in men significantly decreased laxity at 12 months after surgery compared with standard screw fixation.

 

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