The Influence of Reverse-Thread Screw Femoral Fixation on Laxity Measurements After Anterior Cruciate Ligament Reconstruction With Hamstring Tendon

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.

The Influence of Supplementary Tibial Fixation on Laxity Measurements after Anterior Cruciate Ligament Reconstruction with Hamstring Tendons in Female Patients

“…12 The final position of the graft within the tunnel can vary with interference screw fixation, and this has been shown to have an effect on postoperative laxity. 18 In a previous study, it was identified that reverse-thread screws for femoral fixation in right-sided knees allows the graft to adopt a posterior position, which has been shown to significantly reduce the laxity seen in right-sided knee patients 12 months after surgery compared to standard screw fixation. 18 By eliminating this disparity between sides, a more valid comparison can be made between leftsided and right-sided knees.…”

“…A standard 7 × 25-mm RCI interference screw was used for the left femoral fixation, and a reverse-thread 7 × 25-mm RCI interference screw was used for the right femoral fixation. 18 All patients signed informed consent forms. Ethical committee approval was obtained from the Australian Institute of Musculo-Skeletal Research and Sydney University.…”

The outcome at 15 years of endoscopic anterior cruciate ligament reconstruction using hamstring tendon autograft for ‘isolated’ anterior cruciate ligament rupture

“…The 7 mm × 25 mm interference screws used for all fixations in this study were the only size available at the time (1993 and 1994). Subsequent analysis of these patients revealed some laxity in right knees 34 and in females with soft tibial bone. 12 These findings have been incorporated into current practice using undersized-diameter screws in hard bone such as on the femoral side, and oversized-diameter and longer screws in soft bone, which is usually on the tibial side.…”

Tendon healing in a bone tunnel. Part II

“…3 To facilitate anatomic soft-tissue graft fixation, recent reports have described the use of direct tendon fixation with metal or biodegradable interference screws. 4,5 Although clinical data show promising results 6,7 and biomechanical studies have investigated the initial fixation strength of soft-tissue graft interference fit fixation, [8][9][10] there has been no analysis of the progression of tendon-to-bone healing using this fixation. Several animal studies have investigated softtissue graft-to-bone healing using nonanatomic graft fixation.…”