Correlating Preoperative MRI Measurements of Metatarsal Osteomyelitis with Surgical Clear Margins Reveals the Need from 1 Centimeter Resection Margin

SLR - January 2018 - David Cheskis

Reference: Brent Bernstein, Melody Stouder, Eric Ericbronfenbrenner, Steven Chen, David Anderson. Correlating Preoperative MRI Measurements of Metatarsal Osteomyelitis with Surgical Clear Margins Reveals the Need from 1 Centimeter Resection Margin. Journal of Foot and Ankle Research, 2017; 10:40.

Scientific Literature Review

Reviewed By: David Cheskis, DPM
Residency Program: NYU Langone Hospital Systems, Brooklyn, NY

Podiatric Relevance: With the rising diabetic population and high incidence of forefoot amputations, partial ray and metatarsal resections are commonly performed procedures for osteomyelitis (OM). There has been dispute over how much resection is necessary to prevent recurrent infections and how to predict the amount of resection preoperatively. The rate of positive proximal margin rates is 35 to 40 percent. MRI is often ordered prior to surgery to evaluate the extent of osteomyelitis. This article shows how MRI can effectively aid in planning the amount of resection to minimize the chance of recalcitrant OM.

Methods: This is a prospective study performed between 2016 and 2017 to evaluate the rate of residual osteomyelitis after partial metatarsal resections. Twenty-four metatarsals positive for OM in 19 patients with infected submetatarsal wounds with high suspicion of OM were included. Exclusion criteria included Charcot arthropathy, etiology of trauma, prior IV antibiotic treatment to same metatarsal or inability to have MRI. Upon admission, all patients received standard of care, including IV antibiotics, wound cultures, wound measurements, documentation of positive probe to bone, purulent drainage and chronicity of wound. If OM was not found on MRI, these patients were excluded from the study. If OM was confirmed on MRI, the radiologist measured the proximal extension of OM. The distance of OM that was reported by the radiologist was mapped onto the metatarsal and marked by the surgeon. Two proximal resection margin samples were sent from each infected metatarsal. One 0.5 cm proximal to OM marked line and one 1.0 cm proximal.

Results: In 12.5 percent of cases, the MRI was considered a false positive, and these were excluded from the sample study. Fifty percent of samples with 0.5 cm margins had positive proximal resection. By performing a 1 cm resection margin, the positive cultures reduced to 9 percent.

Conclusion: A 1 cm proximal resection margin reduced the positive proximal margin rate from 50 percent to 9 percent, which is a significant improvement from the average positive proximal margin rate of 35 to 40 percent, according to the literature. This study proves that MRI can be used preoperatively to dictate the quantitative amount of resection necessary and, if performed correctly, can significantly reduce residual osteomyelitis after partial metatarsal resections in patients living with diabetes.