CORR Insights^®: Subungual Exostosis of the Toes: A Systematic Review

Where Are We Now?

As an orthopaedic oncologist in an average-sized city, I treat just about every sort of lump and bump from head to toe in babies up to nonagenarians. One of the bone diseases I occasionally see is subungual exostosis. While my residency and orthopaedic oncology fellowship prepared me well to handle bone- and soft-tissue malignancies, along with many benign tumors, I do not recall having seen a single subungual exostosis during my training. These cases often are referred to me by podiatrists. In their systematic review, DaCambra and colleagues detail the current state of understanding for subungual exostosis. In 1996, Davis and Cohen [3] previously reported on 312 patients comprehensively culled from the literature between 1857 and 1994. DaCambra and colleagues have taken a different approach from Davis and Cohen, reviewing only series that included 10 or more patients, resulting in a review of 13 manuscripts totaling 287 cases between 1980 and 2005. Of these 13 manuscripts, three were reported in orthopaedic and dermatology journals respectively, with only one each in foot/ankle, radiology, trauma, pathology, plastics, podiatry, and general journals. This is a condition that clearly falls at the fringes of multiple specialties, and therefore is not concentrated within any single specialty. That is a problem. As for many other relatively uncommon fringe conditions evaluated and treated by many different types of physicians, our ability to gather and advance meaningful information and treatment is limited.

Where Do We Need To Go?

DaCambra et al. emphasize many of the same epidemiologic features as described by others in previously published literature reviews [1, 2, 4, 5], including the young age, preponderance (80%) of occurrence in the great toe, and frequent history of preceding trauma. However, they also describe some differences in comparison to others’ conclusions, including those of Davis and Cohen [3]. According to DaCambra, more patients than previously reported (55% versus 16%) are in the pediatric population, there is closer to a 1:1 ratio than the 2:1 female to male ratio reported in 1996, and the incidence of preceding trauma is higher (29% versus 14%) [2, 3]. While they covered the epidemiology well, the DaCambra report did not offer us much specificity in terms of treatment approaches. DaCambra and colleagues wrote, “The principle of treatment is to achieve complete excision of the lesion by curetting or burring down to normal trabecular bone while minimizing deformity to the nail plate.” This statement fails to provide the best approach to get that done. Do we use a dorsal approach, a distal fishmouth incision with a proximally based flap, or a partial nail excision with a distally based flap? Is there an advantage to one over another in terms of recurrence or nail deformity?

How Do We Get There?

As with many conditions in orthopaedics, we rely upon Level IV evidence because that is all we have at our disposal. Although I commend DaCambra and colleagues for their attempt at a more rigorous analysis of the available literature, the evidence they summarized remains Level IV evidence, and any recommendations therefore are Grade C. In order to provide better recommendations for treatment of subungual exostoses, higher level studies are needed. Prospective evaluation of differing treatment approaches, particularly the dorsal approach compared to a distal fishmouth incision, would seem appropriate along with the endpoints of recurrence and nail deformity. Since orthopaedic journals are a relatively common destination for publications on these entities, orthopaedists would seem as well positioned as anyone else to initiate such prospective studies. My hope is that in another 15 years we see another systematic review of this topic with higher levels of evidence, accompanied by specific evidence-based recommendations in support of one or more specific treatment approaches.