Pull-out vs. suture in zone Ia-Ib flexor tendon injuries: clinical results from a multicentre cohort study

BACKGROUND: Several surgical techniques have been reported for flexor tendon zone 1a-b lacerations without a clear consensus on the gold standard treatment. The purpose of this multicentre study was to measure the outcomes of zone 1a-b flexor tendon injuries treated with a pull-out suture (POS) versus direct suture (DS) technique. PATIENTS AND METHODS: Fifteen patients were treated with the pull-out technique and 22 patients with a direct suture technique between 2014 and 2020. The controlled active motion (CAM) regimen protocol and a standardised follow-up schedule were used in both groups. Data on the demographics, surgery, and treatment characteristics were collected at baseline as well as at week 6 and 13 post-operatively. The primary outcome measurement was the complication rate. Secondary outcome measurements were reoperation rate, finger range of motion (ROM), strength as well as patient satisfaction. RESULTS: The patient age ranged from 18 to 75 years in both groups with all patients having a complete FDP lesion after a clean-cut injury. The complication rate was 41% in the POS group and 16% in the DS group. The reoperation rate was 29% in the POS group and 8% in the DS group. Significant between-group differences in favour of the DS group were found in the passive DIP and passive PIP+DIP ROM at week 6 and week 13. Mean hand strength was 28.7 (11.6) kg in the POS group at week 13 and 21.3 (7.9) kg in the DS group. This difference was statistically significant (p=0.012) with a medium effect size (r=-0.41). Average patient satisfaction at week 13 was 7.5 (2.2) points in the POS and 7.7 (1.3) points in the DS group. The difference between groups was not significant (p=0.839). CONCLUSION: This register-based study demonstrates lower complication and reoperation rates with the direct suture approach compared with a pull-out button technique. Although clinical results were similar between the two surgery techniques at week 13 post-surgery, a direct suture approach should always be attempted whenever possible. If necessary, other local structures should be included to increase suture strength and allow for early active motion rehabilitation regimens.