Clinical outcome of Bio-Tenodesis Screw Versus Bone Tunnel Fixation of Flexor Hallucis Longus Tendon Transfers to the Calcaneus in chronic Achilles tendon rupture: Retrospective Cohort Study

BACKGROUND : Due to the decrease in performance of patients and the lack of return to previous activity in patients with chronic Achilles tendon rupture (CATR), the treatment is surgery in most cases. Our main aim in this study is to compare the clinical results and postoperative complications of the Flexor halluces tendon (FHL) fixation technique with bio tenodesis screw (BTS) versus the bone tunnel (BT) technique in the calcaneus bone. METHODS : A retrospective cohort study in which patients were treated with two different FHL tendon fixation techniques, from September 2018 to September 2023.The evaluation included demographic information, complications (infection and dehiscence of the wound at the surgical site and re-rupture and sural nerve damage and deep vein thrombosis), duration of surgery, length of surgical incision. The Achilles Tendon Total Rupture Score (ATRS), and the American Orthopedic Foot and Ankle Society (AOFAS) scores of the patients at the 3th, 6 ^{th and 12 th months of follow-up. RESULTS : The mean age of all patients in this cohort study was 34.7±1. The mean age (P=0.24), gender distribution (P=0.76), and body mass index (P=0.25) were similar for both groups. The mean operation time (group A: 63.9±7.6vs. group B: 57.1±7.8, P=0.86) and mean surgical incision length (group A: 18.2±3.4 vs. group B: 14.4±4.5, P=0.51) was not statistical difference between two groups.There was no statistical difference between groups regarding functional results at 3th (ATRS: group A: 79.4±5.7 vs. group B: 81.4±5.8, (P=0.87), and AOFAS: group A: 77.9±9. vs. group B: 81.6±7.9, (P=0.67)) and 6th months (ATRS: group A: 78.8±7.8 vs. group B: 83.5±5.9, (P=0.16), and AOFAS:group A: 83.3±5.4 vs. group B: 82.6±6, (P=0.54)). There was statistical difference between groups regarding functional results at 12th (ATRS: group A: 82.89±9.4 vs. group B: 83.84±6.6, (P=0.028), and AOFAS:group A: 81.51±8.9 vs. group B: 85.34±5.2, (P=0.01)). We observed four postoperative complications (13.6%) in groupA. two patients (6.8%) had a re-rupture, one patient (3.4%) had sural nerve injury and one patient (3.4%)superfacial infection. There were two complications (7.6%) in group B. one patient (3.8%) had re-rupture,and one patient (3.8%) had dehiscense of incision.(P:0.43) CONCLUSION : FHL tendon fixation to the calcaneus bone with the bio-tenodesis screw technique was a less invasive method and had good clinical results in long-term follow-up than the bone tunnel technique.}