SLR - January 2020 - Nicholas D. Stepnoski
Reference: Myerson, C. Lucas, Myerson, Mark S., Coetzee, Chris, McGaver, Rebecca Stone, Giveans, M. Russel. Subtalar Arthrodesis with Use of Adipose-Derived Cellular Bone Matrix Compared with Autologous Bone Graft. J Bone Joint Surg Am. 2019 Nov 6;101(21):1904-1911.Scientific Literature Review
Reviewed By: Nicholas D. Stepnoski, DPM
Residency Program: AMITA Health, St. Joseph Hospital – Chicago, IL
Podiatric Relevance: Subtalar arthrodesis is an effective procedure in treating hindfoot pathologies when conservative treatments fail. This allows proper alignment of the subtalar joint and return to activity with decreased pain. However, failure of fusion results in nonunion and is reported at 5 percent to 45 percent with use of bone graft in diagnostic imaging. Historically, autologous bone graft has been beneficial in achieving osseous union in the joint, yet has its disadvantages such as donor site morbidity. Alternatively, adipose-derived cellular bone matrix (ACBM) is composed of partially demineralized cancellous bone and live cells capable of bone formation. The purpose of this prospective, multicenter, randomized controlled trial was to evaluate the efficacy and safety of ACBM compared to autologous bone graft for subtalar arthrodesis.
Methods: Between July 2010 and September 2014, 125 patients were enrolled at six sites for subtalar arthrodesis. Inclusion criteria consisted of diagnosis of arthritis, an age of 18-80 years, and other diagnoses requiring fusion of the subtalar joint. Exclusion criteria included neuropathy, vascular insufficiency, severe deformities, active infection, and bone supplementation within 12 months. Double blind randomization occurred in a 1:1 ratio of ACBM: autograft. All patients underwent standard joint preparation of the subtalar joint. 3-4 cc of autograft was harvested from the lower extremity and placed in the sinus tarsi. ACBM was placed in the sinus tarsi and posterior facet. Fusion sites were fixated with partially threaded screws and both groups followed the same post-operative protocol. Radiographs of both groups were obtained at six weeks, three months, six months, one and two years. CT scans were obtained at six months.
Results: A total of 109 patients underwent arthrodesis with autograft (64) or ACBM (54) and subjected to analysis. Radiographic endpoint of fusion was defined as > 45 percent osseous bridging across the posterior facet of the subtalar joint on CT. Of the ACBM and autograft group, 30.8 percent and 54.4 percent respectively, had subtalar joint fusions within parameters on CT at six months. Evaluation of clinical and radiographic fusions were also measured for ACBM and autograft groups, which were 78.8 percent and 87.7 percent respectively. At 6 months, AOFAS scores increased 40.4 to 72.8 for the ACBM group and from 43.4 to 76.0 for the autograft group.
Conclusions: The use of ACBM provided inferior results of osseous union in subtalar arthrodesis when compared to autograft. The goal of this paper was to investigate a less invasive alternative in fusion in avoiding donor site morbidity. Even though the hopeful finding of a new adjunct in fusion was negated, researchers can continue their search for alternatives to the historically used autograft. Also, it is important to note the favorable use of autograft reported only 54.4 percent union on CT at six months, which leads the investigator to believe there are other viable options available and/or current methods require improvement. This study represents the continued search of a substitute as effective as autograft, and even in its poor outcome, brings surgeon and patient closer to its replacement.