Delayed repair of tendon to bone injuries leads to decreased biomechanical properties and bone loss

Abstract

Introduction. Repair of the torn rotator cuff tendon is a common procedure performed in the shoulder. In the clinical setting, a significant delay between rotator cuff tear and subsequent repair often exists. The purpose of this study was to investigate the biomechanical properties and bone density of the tendon to bone repair site after acute and delayed repair.Methods. The supraspinatus tendons in bilateral shoulders of 60 rats were transected from the bone. In the acute group, the tendons were immediately repaired with suture. In the delayed group, the tendons were allowed to retract and repaired in a second procedure after a 3-week delay. Cross sectional area and biomechanical properties were evaluated. Bone density of the humeral head was assessed using peripheral quantitative computed tomography. Histologic sections were obtained and examined.Results. At 10 days the repair tissue displayed vascular and fibroblast proliferation accompanied by predominantly mononuclear infiltrate. At 28 days the inflammatory process gradually decreased. No significant histologic differences were noted between the acute and delayed repair specimens. Cross-sectional area was higher in the delayed group at the early time points (44% at 10 days and 3 1% at 28 days). Viscoelastic properties were greater in the acute group at the early time points and significantly less at the latest time point, compared to the delayed group. Bone density was markedly decreased (8% and 12%, 28 and 56 days respectively) in the delay group.Discussion. Inferior rotator cuff healing was demonstrated when there was a delay between injury and repair. Viscoelastic properties of the acute repairs were increased compared to the delayed group at 10 days, indicating tendon stiffening during the 3-week delay before repair. Viscoelastic properties of the acute repairs were decreased compared to the delayed group at 56 days indicating deterioration of properties over time in the delayed group. The deterioration in properties in the delayed group coincide with bone density decreases in the greater tuberosity. These results indicate that bone loss may a significant factor in poor healing.

Alendronate reduced peri-tunnel bone loss and enhanced tendon graft to bone tunnel healing in anterior cruciate ligament reconstruction

“…However, these were not randomised or controlled clinical studies. Bone loss after tendon insertion site injury and repair has also been reported in animal studies (Rodeo et al, 1999;Silva et al, 2002;Ditsios et al, 2003;Galatz et al, 2005;Wen et al, 2009). There was significant reversible decrease in BMD around the knee joint as measured by dual-energy X-ray absorptiometry (DXA) in patients undergoing ACL reconstruction in a randomised controlled trial comparing bone loss with different surgical techniques (Lui et al, 2012).…”

“…Despite the relatively high rate of positive outcome reported, graft failure continues to occur. Such graft failure is mainly attributed to surgical errors, traumatic injuries, failure of graft osteo-integration and graft remodelling (George et al, 2006). Further, healing of harvested ACL grafts is very slow.…”

The Role of Mechanical Loading in Tendon Development, Maintenance, Injury, and Repair

“…Previous work has shown inferior healing when operative repair is delayed following injury [57][58][59] . While current therapies produce functional outcomes in the short term, long-term repair outcome varies with respect to type of injury, injury location, and severity 38,40 .…”

“…In an effort to improve tendon-to-bone healing, the application of static or cyclic loading at the insertion site may be necessary to restore the zonal phenotype 60,[65][66][67] . Additionally, the repair tension, the amount of tension placed on a tendon to reattach it to bone, is important in recreating the insertion site 59 . Stasiak et al developed a knee joint fixation system to study tendon and ligament-to-bone healing in a rat model of anterior cruciate ligament reconstruction 65 .…”

Alendronate prevents bone loss and improves tendon‐to‐bone repair strength in a canine model

“…5,[7][8][9] Although the tendon stump becomes hypercellular following injury, producing abundant amounts of new matrix, 5,7 the bone near the insertion shows progressive decreases in bone mineral density (BMD). 8,9 Bone loss following tendon or ligament injury has been noted at a number of insertion sites, including the flexor tendon, the rotator cuff, the Achilles tendon, and the anterior cruciate ligament. 8,[10][11][12][13] These results suggest that bone resorption is an important factor contributing to the accrual of repair site strength.…”