Bunion Surgery Works--Except When It Doesn't: Commentary on an article by Peter Bock, MD, et al.: "The Scarf Osteotomy with Minimally Invasive Lateral Release for Treatment of Hallux Valgus Deformity. Intermediate and Long-Term Results".

Abstract

Commentary Hallux valgus remains, in many ways, the flagship condition of orthopaedic foot and ankle practice, occupying prominent early chapters in standard textbooks and continuing to fill journals at all levels of academic discourse. It also continues to be a largely soluble problem—except when it isn’t. The relatively high overall satisfaction rates reported in Level-IV follow-up studies, seemingly regardless of specific technique, render the analysis of the small number of clinical failures difficult. The challenge in all studies of the condition has transformed from that of painting a broad picture of success in the many to understanding what failed in the maddening few. The paper by Bock et al. is not revolutionary, nor is it fully generalizable beyond the Scarf osteotomy, but it does hold incremental lessons large and small toward this end. The first incremental lesson is simple. The patients undergoing the procedure perceived themselves to be better for having done so, and that perception lasted, on balance, at least ten years. The chief psychometric instrument used in the study, the American Orthopaedic Foot & Ankle Society (AOFAS) scoring system, prohibits any finer analysis of this statement. The score is nonvalidated and contains subscores that are likely highly interrelated; it cannot be presumed to behave in a linear fashion or produce normally distributed data. The authors have appropriately recognized these limitations and modified their analyses accordingly. Median scores rather than means are reported for these data, and nonparametric statistical methods are used. Additionally, the usual limitations of a Level-IV study apply: the patients have themselves chosen to undergo the procedure and surgeon selection bias is inevitable. Less powerful statistics and a less powerful methodology lead to a less powerful conclusion; this group of selected patients perceived themselves to be better than they were preoperatively. How much so remains indeterminate. The second lesson is more surprising. Radiographic recurrence was unmasked by the long-term follow-up at a remarkably high rate. Recurrent deviation of the toe proved to be a necessary but not sufficient condition for clinical failure: while nearly all patients with long-term pain had a recurrence, not all recurrences were painful. Just who suffers a recurrence and why remain elements of debate. The authors have noted that both higher intermetatarsal angles and more severe stations of sesamoid subluxation were significant risk factors. The former may represent an inherent limitation of the Scarf osteotomy itself. While a detailed case-by-case failure analysis is not presented, it is possible that subtle tarsometatarsal instability in either the axial or sagittal plane may be at work or that the osteotomies were themselves slightly undercorrected. In either case, the residual osseous deformity may overpower a toe held straight on the basis of soft-tissue balancing alone. The sesamoids and, by extension, the first metatarsophalangeal joint itself represent a more subtle potential source of recurrence. The concept is not a new one. Sesamoid station has been shown to be a risk factor for recurrence on the basis of preoperative and early postoperative radiographs. Disordered tracking of the sesamoids relative to the plantar crista of the metatarsal head may, in fact, be relatively underemphasized in preoperative analysis1,2. Similarly, dysplasia of the metatarsal head itself has been demonstrated to be associated with radiographic recurrence3. In the current study, a limited soft-tissue procedure without full release of the lateral sesamoid ligament was performed; it therefore can be assumed that any residual lateral contracture may be clinically important only when higher degrees of preoperative deformity are encountered. Hallux valgus surgery remains an orthopaedic success story, but that story remains tempered by a surprisingly high rate of radiographic recurrence and a low but obstinate rate of clinical failure. The rough elements of success are clear regardless of the specific surgical technique: correct the intermetatarsal angle and achieve a stable first ray. To further improve outcomes, the devil appears to reside in the details, and there are lots of details. Our challenge, as this study further illustrates, is to learn in which ones he makes his home.