SLR - February 2017 - Jordan Hoachlander

Randomized, Prospective Comparison of Bioabsorbable and Steel Screw Fixation of Lisfranc Injuries

Reference: Ahmad J, Jones K. Randomized, Prospective Comparison of Bioabsorbable and Steel Screw Fixation of Lisfranc Injuries. J Orthop Trauma. 2016 Dec;30(12): 676–681

Reviewed By: Jordan Hoachlander, DPM
Residency Program: Suburban Community Hospital

Podiatric Relevance: Injuries to the midfoot tarsometatarsal (TMT) or Lisfranc joint complex can occur in a multitude of ways that result in varying degrees of joint displacement, ligamentous injury and bony involvement. In addition, injuries involving TMT joint incongruity, fractures and/or diastasis may present a challenging task for foot and ankle surgeons when deciding how to fixate these unstable injuries. Routinely, these injuries are surgically treated with ORIF using steel screw fixation. However, transarticular screws may be a source of iatrogenic cartilage damage and are at risk for breaking during the patient transition to full weightbearing. An alternative option to fixate the injury is the use of bioabsorbable screws. Although not as mechanically strong as steel screws, bioabsorbable screws provide stability of the Lisfranc complex and also reduce the need for an additional surgical procedure to remove hardware. To empirically compare these approaches, the aim of the present study was to evaluate outcomes of bioabsorbable versus steel screws in the acute treatment of Lisfranc injuries.

Methods: A prospective and randomized design was used to conduct this study between September 2008 and December 2013 at the Rothman Institute of Orthopaedics at Thomas Jefferson University Hospital in Philadelphia. Inclusion criteria included any acute unstable Lisfranc injury where open reduction internal screw fixation was warranted and physical evaluation was performed within four weeks of the initial date of injury. Chronic or unstable fractures with comminution that required midfoot arthrodesis were excluded. Upon evaluation, all patients had a full series of weightbearing foot radiographs, and a subsequent MRI or CT scan was ordered to clarify the extent of TMT joint and ligament damage. The injuries were classified into groups based on the extent of injury, including total incongruity (Type A), partial incongruity (Type B1 or B2) or divergence (Type C1 or C2). Preoperatively, the patients were assessed clinically and functionally using the Foot and Ankle Ability Measures (FAAM) and 10-point Visual Analog Scale (VAS) of pain. On the day of surgery, the independent observer randomized all 40 patients into two groups, 20 patients who would have steel screw fixation and 20 who would have bioabsorbable screw fixation. Steel screw fixation was performed using 4.0 mm partially threaded cannulated cancellous steel screws (Synthes), and bioabsorbable fixation was performed using 4.5 mm partially threaded cannulated cancellous polylactic acid (PLA) screws (Smart Screw, Arthrex). All patients underwent a similar postoperative course, including two weeks NWB in a posterior splint and a gradual transition into a CAM walker and PWB between eight and 12 weeks. At 16 to 20 weeks postop, all patients could return to athletic activity without restrictions. Patients with steel screw fixation also had their hardware removed after six months and again were transitioned to full activity in four weeks. To evaluate hardware failure or breakage and arthritic changes, radiographs were taken at all postoperative visits (weeks two, six and 12) and additionally at six months and one year later. The Statistical Package for the Social Sciences (SPSS) was used for all statistical analyses.

Results: The 40 total patients were divided into two groups of 20 and matched for similar distribution of sex, age, side of surgery, involvement in workers’ compensation claim, type of Lisfranc injury and preoperative FAAM and VAS scores. Of the 20 patients who had open reduction internal steel screw fixation for treatment of their acute injury, 15 patients had a Type B2 injury, three with Type C1 and two with Type A. The steel screw fixation group had a mean follow-up of 40.5 months, and all 20 patients had full joint healing and stability with no hardware breakage. Final FAAM scores increased from 24.9/100 preoperatively to 89.6/100, and final VAS scores decreased from 6.5/10 preoperatively to 1.9/10. In addition, 4/20 (20 percent) patients in this group developed radiographic evidence of midfoot arthritis with joint space narrowing. Further, two patients indicated mild pain and two reported moderate pain; however, none of these patients had additional surgery or arthrodesis. For the group of 20 patients who underwent open reduction internal bioabsorbable fixation for treatment, there were 17 patients with a Type B2 injury, two with Type C1 and one with Type A. This group had a mean follow-up of 36.3 months. At 4.5 months, all 20 patients had full joint healing and stability at the midfoot. Final FAAM scores increased from 32.5/100 preoperatively to 91.2/100, and final VAS scores decreased from 4.7/10 preoperatively to 1.3/10. In addition, 2/20 (10 percent) of the patients developed joint space narrowing indicative of midfoot arthritis, with both patients reporting moderate pain. It is important to note that 1/20 (five percent) patients returned to the OR two years postoperatively for treatment of an inflammatory and lytic reaction at an unabsorbed screw head.

Conclusions: This study indicates that outcomes are comparable between steel screws and bioabsorbable screws in the treatment of acute, unstable Lisfranc injuries. Specifically, both types of screws provide adequate fixation resulting in improved midfoot stability, midfoot function and pain relief. Thus, bioabsorbable screw fixation may be a valid alternative treatment option for acute, unstable Lisfranc injuries. Although more research is needed, bioabsorbable screws could play an integral role in the fixation of podiatric fractures and improving patient care. 

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