Tensioning Ligament and Tendon Repairs to Bone Using a Modified Screw-post Technique

Abstract

The purpose of this study was to demonstrate how to tension tendon and ligament repairs or reconstructions to bone by using an oblique screw-post. A controlled experiment simulating this repair technique is reported, followed by 5 case examples. A wood frame model was used to test 5 initial exposed screw lengths (4, 8, 12, 16, 20 mm) and 5 screw angles [90 (perpendicular to wood plane), 75, 60, 45, 30 degrees]. A spring-based force gauge was tied to the exposed 3.5 mm cortical screw with a washer using a #2 nonabsorbable braided suture, and the screw was fully advanced. System lengths were measured before and after advancement using digital calipers. Screw angles were measured with a protractor. Analysis of variance with post hoc paired t tests was performed to compare changes in system length with different initial exposed screw length and screw angle. Greater changes in system length was achieved with decreasing screw angle and increasing initial exposed length (P<0.05). A maximum change in system length of 12.4 mm (SD=0.4 mm) was achieved with a 45-degree screw with 20 mm initial exposed length (P<0.05). Five case examples where a screw-post was used to repair tendons and ligaments in the upper extremity are described. An oblique screw-post can advance a tendon or ligament repair to bone. This can result in increased tension of the repaired structure, potentially providing a better repair or greater joint stability.