Hard-Soled Shoe Versus Short Leg Cast for a Fifth Metatarsal Base Avulsion Fracture: A Multicenter, Noninferiority, Randomized Controlled Trial

SLR - March 2021 - Isaiah Song

Reference: Choi YR, Kim BS, Kim YM, Park JY, Cho JH, Kim S, Kim HN. Hard-Soled Shoe Versus Short Leg Cast for a Fifth Metatarsal Base Avulsion Fracture: A Multicenter, Noninferiority, Randomized Controlled Trial. J Bone Joint Surg Am. 2021 Jan 6;103(1):23-29. doi: 10.2106/JBJS.20.00777. PMID: 33252586.

Level of Evidence: Therapeutic Level 1

Scientific Literature Review

Reviewed By: Isaiah Song, DPM
Residency Program: Swedish Foot and Ankle Surgery – Seattle, WA

Podiatric Relevance: Conservative treatment for fifth metatarsal base avulsion fractures with protected weight-bearing has shown to be successful. Compared to a tall walking boot or a short leg cast (SLC), a hard-soled shoe is lightweight and more convenient for the patient. The authors looked at patient reported outcomes in regards to pain and function of using a hard-soled shoe vs a cast for fifth metatarsal base avulsion fracture. They hypothesized that not only would a hard-soled shoe be non-inferior to SLC in terms of pain, but also have better satisfaction and a shorter time to recovery. 

Methods: This prospective, randomized trial reviewed 145 patients ages 18-65 with a Zone 1 avulsion fracture. Exclusion criteria included other fifth metatarsal fractures, open fractures, pathologic fractures, other concurrent lower-extremity injuries, obesity, diabetes and neuroarthropathy. Patients were randomized to the hard-soled shoe or cast group. Patients were immobilized in a short leg posterior splint for one week, then transitioned to protected weightbearing in a hard-soled shoe or a cast for four weeks. Use of crutches was permitted. Outcomes were evaluated with the 100-millimeter VAS at six months and the Olerud-Molander score (OMS), looking at recovery of function at the four-week, eight-week, 12-week and six month follow-up visits. Radiographs were also obtained at these visits for assessment of union.

Results: Of the 96 patients included in the study, 46 were randomized to the hard-soled shoe group and 50 to the cast group. There were no significant baseline characteristic differences between the two groups. There were no significant differences between the two groups using the 100-millimeter VAS or patient reported satisfaction. Time to return to pre-injury activity was significantly shorter in the hard-soled shoe group. The OMS was significantly higher for the hard-soled shoe group at the four week mark, but not at later follow-up visits, signifying quicker functional recovery. There was one case of delayed union in the hard-soled shoe group and two in the cast group, which all healed by final follow-up. There were two cases of displacement in the cast group that healed with delayed weightbearing.

Conclusions: Standard conservative treatment for fifth metatarsal base avulsion fractures has been short leg casts due to concerns for fracture displacement from the pull of the peroneus brevis with ankle motion. However, cadaveric studies have shown weightbearing stimulation on the peroneus brevis tendon causes minimal widening of artificial fifth metatarsal avulsion fractures. The peroneus brevis extends ~15.2 millimeters distal to the tip of the tuberosity and terminates at the broadest portion. Avulsion fractures usually occur within the insertion. Because of this, the pull of the peroneus brevis tendon may have a tension-band effect on the avulsion fracture and ankle mobilization may accelerate the healing process. This study found that hard-soled shoes allowed for early functional mobilization and a quicker return to activity while remaining noninferior in regards to patient reported pain. The hard-soled shoe may be a more appropriate choice of immobilization for conservatively treated fifth metatarsal base avulsion fractures.