O3254: Tendon Transfer Fixation in Patients with Neuromuscular Disease

Background: Historically, tendon transfers about the foot and ankle in the neuromuscular population have been secured with sutures or with sutures tied over a button (Button). These strategies usually require non-weight bearing (NWB) immobilization after surgery and buttons pose the risk of a skin pressure sore on the plantar aspect of the foot. Interference screw fixation (ISF) uses a small diameter bioabsorbable screw to secure fixation after a tendon transfer. They are routinely used in adult foot and ankle reconstruction procedures because they provide secure fixation and enable early weightbearing (WB). In addition, ISF should minimize the risk of skin injury from the transfer. This study reports on our experience with ISF in tendon transfers of the foot/ankle for patients with neuromuscular disease.

Methods: Patients with neuromuscular etiology who underwent a tendon transfer of the foot or ankle at a single center tertiary care children’s hospital between 2013-2023 were included. Demographics such as age, race, sex, neurological diagnosis, and surgical procedures were collected for all patients meeting inclusion criteria. An ISF failure was defined as either the screw pulling out intraoperatively or by instability of initial fixation with the screw necessitating supplementary suture or button fixation.

Results: A total of 109 patients (46 female, 63 male) with a mean age of 9.95±3.26 years met inclusion criteria. Forty-seven (43.1%) patients were diagnosed with CP while 62 (56.9%) had a non-encephalopathic neurologic condition (CMT, spina bifida). Overall, 102 (93.5%) patients were ambulatory at baseline and 7 (6.42%) were non-ambulatory. 76 (69.7%) patients were treated with ISF, 24 (22%) with a suture fixation, 4 (3.7) with button fixation, and 6 (4.6%) with ISF and a button due to instability/failure of the screw. There was an overall failure rate of 5.5% for ISF. We found no evidence of any relationship between preoperative ambulation and screw fixation failure (p=0.335). Postoperatively, 40 (36.7 %) patients were immediately weight bearing as tolerated (WBAT) while 69 (63.3%) remained NWB for at least 2 weeks. There was a significant difference in post-op WB status by fixation type (p < 0.001) with ISF patients weight bearing at a higher rate immediately following surgery. However, there were no significant differences in postoperative skin breakdown by fixation type or weight bearing.

Conclusion: ISF is a viable option for neuromuscular patients undergoing a tendon transfer of the foot or ankle and can be used successfully irrespective of ambulatory status. We did not appreciate a difference in skin breakdown between fixation strategies but did find that patients with ISF were released to full weightbearing significantly earlier. However, attention should be paid to fixation quality intraoperatively, and if there is concern, supplementary fixation should be considered.