When Is Primary Metacarpal Corrective Osteotomy Recommended in Patients with Flatt Type IV Radial Polydactyly?

It is with great interest that we read the article by Seok Woo Hong and colleagues titled “When Is Primary Metacarpal Corrective Osteotomy Recommended in Patients with Flatt Type IV Radial Polydactyly?”1 The authors performed a retrospective cohort study to compare metacarpal osteotomy and soft-tissue procedure alone in patients with Flatt type IV radial polydactyly, in terms of the indication for primary metacarpal corrective osteotomy. Overall, it is an interesting study. Nevertheless, we would like to communicate several queries to the authors. 1. With a retrospective nature, the bias of patient selection should be cautiously avoided to draw a reliable conclusion. In this article, intraoperative radial stress tests were performed to decide whether the metacarpal osteotomy procedures should be used. They were subjective tests and may vary among doctors. We wondered whether an analysis should be done to evaluate the bias. 2. In this article, the authors found that the surgical outcomes were gratifying in most of the patients who underwent metacarpal osteotomy. Among patients who did not undergo metacarpal osteotomy, they discovered that preoperative metacarpal deviation angle values were large in those with unsatisfactory outcomes and the metacarpophalangeal joint angulation was not fully corrected after the surgery. Thus, the authors hypothesized that the correction power of the soft-tissue procedures had a limit and suggested metacarpal osteotomy should be done when the preoperative metacarpal deviation angle was larger than 10.8 degrees. As we know, inadequate correction of the bony axis and soft-tissue (tendon and collateral ligament) imbalance are two important factors attributed to residual angulation. We do agree with the view that the osteotomy procedure is a robust method for correcting the bony axis of Flatt type IV radial polydactyly and should be encouraged, especially in those with severe angulation of metacarpophalangeal joints. However, we doubt that metacarpal osteotomy could correct joint angulation among all the patients. Some studies2–4 have shown that the results may be not that encouraging. Recurrences of the angular deviation were commonly seen in those patients who had undergone metacarpal osteotomy, which suggests that the soft-tissue procedure should be strengthened in primary surgery. 3. In this study, 5 degrees of residual angulation was observed 2 years after the surgery. The authors advised a 5-degree overcorrection could be considered when planning metacarpal osteotomy. Based on the results given by this article, we think it is a good attempt, since 5 degrees of remnant deviation is acceptable. It is feasible to plan a 5-degree overcorrection before surgery, indeed; however, it may be a little hard to evaluate and control in clinical application, considering that the width of the metacarpal bone is usually less than 10 mm in a 1-year-old child. 4. Otherwise, as for the question “When is primary metacarpal corrective osteotomy recommended in patients with Flatt type IV radial polydactyly,” we suggest doing some research on the size of the two digits. A study5 found that a relatively bigger excised digit was a factor causing poor results, despite intensive reconstructive surgery. In our experience, a smaller extra digit often correlates with a bigger preserved digit whose soft tissue (tendons and collateral ligaments) is well developed, and which is less likely to need metacarpal osteotomy. DISCLOSURE None of the authors has a financial interest to declare in relation to the content of this communication.