Session IX - Foot & Ankle

Bioabsorbable versus Stainless Steel Screw Fixation of the Syndesmosis in PLR Ankle Fractures: A Prospective, Randomized Trial

David B. Thordarson, M.D; Michael Samuelson, MD; Lane E. Shepherd, MD; Paul F. Merkle, MD; Jackson Lee, MD, University of Southern California, Los Angeles, CA

Purpose: The purpose of this study was to compare the results of operative treatment of PLR fractures using standard lateral plate fixation with either stainless steel screws or bioabsorbable PLA screws in a prospective, randomized fashion.

Methods: After obtaining Institutional Review Board approval, 32 patients were enrolled in the study. All patients sustained PLR ankle fractures with significant syndesmotic disruption (JOT Type 44C). Inclusion criteria included PLR fractures occurring 3.5 cm or more proximal to the ankle joint or lower if significant lateral displacement of the talus occurred at the time of injury (>1 cm). All patients had intra-operative assessment of syndesmotic stability after plate fixation and were found to have persistent instability. Seventeen patients were randomized to plate fixation with a 4.5-mm PLA absorbable screw, and 15 patients were randomized to standard fixation with a 4.5-mm stainless steel screw. There were 7 females and 25 males. All injuries occurred with an external rotation twisting force in the ankle. Stainless steel and PLA screws were placed in identical fashion across 4 cortices. All patients were kept non-weight bearing for 6 weeks and in a short-leg walking cast for 2 additional weeks. The cast immobilization was routinely removed at 8 weeks following surgery. The stainless steel screws were removed 12 weeks after surgery. The PLA screws were not removed. Average follow-up was 16 months (range: 3-30 months).

Results: All 32 patients had uncomplicated healing of their fracture. There was no evidence of osteolysis or sterile effusion in any patient in the PLA group. There were no wound complications in either group. At the most recent follow-up, most of the patients had a similar degree of mild pain in the ankle with prolonged standing or walking. No difference in the range of motion between the 2 groups was noted. No patients complained of pain or tenderness over the absorbable screw head.

Discussion: Previous studies have documented that stainless steel syndesmotic screws which are not removed can break or result in significant osteolysis about the screws. This study demonstrated that patients had a similar result at short- to intermediate-term follow-up whether a stainless steel screw or PLA screw was used. We believe the use of PLA syndesmotic screws is an attractive alternative to stainless steel screws fixation in order to avoid the subsequent morbidity and cost of removal of stainless steel screws.

Conclusions: Use of an absorbable PLA syndesmotic screw among patients with a PLA fracture obviated the need for removal. Similar patient outcome was noted in the 2 groups without the necessity of and subsequent morbidity of the second procedure to remove a standard stainless steel screw.