This study was a retrospective comparative study of the effectiveness off the biplanar versus triplanar chevron osteotomy in the management of mild to moderate hallux valgus. Specifically, we aimed to determine if the triplanar chevron osteotomy resulted in superior correction of the DMAA when compared to the biplanar chevron osteotomy.
Since the chevron osteotomy was first described in 1981, many studies have evaluated its effectiveness in the management of hallux valgus (4, 13, 14). It has typically been used for the management of mild to moderate hallux valgus, in patients with an IM angle of 15 degrees or less, without osteoarthritis of the 1st metatarsophalangeal (MTP) joint. For patients with a larger IM angle of greater than 15 degrees, a more proximal osteotomy such as the scarf osteotomy is more commonly performed (2). In high quality studies including randomised controlled trials and systematic reviews, the chevron osteotomy has proven to be a safe and effective procedure for managing mild to moderate hallux valgus (13). Studies have demonstrated that the chevron osteotomy successfully and predictably reduces the IM and hallux valgus (HV) angles in mild to moderate hallux valgus (13–17). In addition, the chevron osteotomy results in a significant improvement in patient reported outcome measures such as the VAS and AOFAS scores at both short and long term follow up (13–17).
Our study has demonstrated that a biplanar chevron osteotomy was associated with a mean reduction in IM angle of 4.46 degrees (95% CI 3.94 to 4.99, p = < 0.001), which was statistically significant. Similarly, a triplanar chevron osteotomy was associated with a mean reduction in IM angle of 5 degrees (95% CI 4.37 to 5.63, p = < 0.001), which was statistically significant. There was no significant difference in postoperative IM angle between each group postoperatively (p = 0.279). These results are consistent with the findings in the current literature. A systematic review of 25 studies including a total of 1029 patients published in 2012 showed that the chevron osteotomy significantly reduces the IM angle by a mean of 5.33 degrees (95% CI, 5.12 to 5.54, p < .001) (15). A more recent large cohort study by van Groningen et al demonstrated a significant mean reduction in IM angle of 6.1 degrees (95% CI 5.9 to 6.4, p = < 0.001) following chevron osteotomy for hallux valgus correction (18). Our findings are therefore consistent with the current literature and suggest that both a biplanar and triplanar modification of the chevron osteotomy are equally effective in reducing IM angle toward normal in mild to moderate hallux valgus deformity.
As demonstrated in Figs. 1 and 2, the DMAA is the angle formed by a drawing a perpendicular line to the long axis of the first metatarsal and the distal articular surface of the first metatarsal (2, 9, 10). In hallux valgus, the DMAA describes the valgus angulation of the distal articular surface of the 1st metatarsal head. The reason that the DMAA is important in assessing hallux valgus deformity, is because valgus angulation of the distal articular surface of the 1st metatarsal head is one of the most frequently cited bone deformities in hallux valgus (19–20). While the existence of the DMAA and role of the DMAA in hallux valgus development and progression has been questioned by some authors in recent years, a recent high quality comparative study using 3D weightbearing CT has confirmed that valgus deformity of the articular surface of the 1st metatarsal head is present in those with hallux valgus when compared to control subjects (20).
In a recent systematic review, the prevalence of hallux valgus recurrence following surgery ranged from 9–73% across 23 studies based on 2914 individuals, with a pooled prevalence of hallux valgus recurrence of 24.86% following surgery. The variation in reported recurrence rates most likely represents the substantial variation in duration of follow up, definition of what constitutes hallux valgus recurrence, incomplete reporting, surgical technique, and preoperative deformity across studies (21).
Several studies have demonstrated that an increased preoperative DMAA and an inadequately addressed postoperative DMAA, which may occur following inadequate correction of the DMAA during surgery, is associated with a more severe progression of hallux valgus preoperatively, and an increased risk of hallux valgus recurrence postoperatively (22–25). Park and Lee, in a study investigating hallux valgus recurrence in patients who had a chevron osteotomy for hallux valgus correction, noted that at a mean follow up of 27.5 months, the immediate postoperative DMAA was much larger in those who had hallux valgus recurrence compared to those who did not have hallux valgus recurrence (25), suggesting that a larger postoperative DMAA may be associated with a greater risk of hallux valgus recurrence.
Our study has demonstrated that the use of a triplanar chevron osteotomy can significantly reduce the postoperative DMAA in mild to moderate hallux valgus. While this study also suggested that the biplanar chevron osteotomy significantly reduces the DMAA in mild to moderate hallux valgus, the mean change was significantly higher in the triplanar group when compared with the biplanar group (Tables 2 and 3).
Table 2 also demonstrates that there was a significant difference in the preoperative DMAA between the biplanar and triplanar groups, with the DMAA of the triplanar group significantly higher than the biplanar group. This is because the biplanar chevron osteotomy was used for the correction of hallux valgus in patients with a smaller DMAA, with the triplanar chevron osteotomy reserved for cases with a more significant preoperative DMAA abnormality. The fact that the preoperative DMAA was significantly higher in the triplanar chevron group compared to the biplanar chevron group, and the postoperative DMAA was significantly lower in the triplanar chevron group compared to the biplanar chevron group, demonstrates the ability of the triplanar chevron osteotomy to powerfully correct the DMAA toward normal. Given that inadequate correction of the DMAA has been associated with hallux valgus recurrence, the authors suggest that the triplanar chevron osteotomy may be more effective than the biplanar chevron osteotomy in reducing the risk of recurrence of hallux valgus in those with a larger DMAA abnormality. However, long term radiographic follow up data is required to confirm whether or not achieving adequate DMAA deformity correction truly reduces hallux valgus recurrence in the postoperative period.
The authors suggest that the addition of a medial closing wedge osteotomy results in superior correction of large DMAA in mild to moderate hallux and therefore should be considered in the management of hallux valgus with a large DMAA.
Limitations
A major limitation of this research study was the lack of long term radiographic follow up. This limitation means that while superior correction of the DMAA can be achieved with a triplanar chevron osteotomy compared to a biplanar chevron osteotomy, it is not possible to confirm whether or not this has reduced recurrence in this cohort. Nevertheless, this study is the first study to demonstrate a significant improvement in DMAA reduction with the addition of a medial wedge closing osteotomy in a triplanar chevron osteotomy when compared with a biplanar chevron osteotomy in the correction of mild to moderate hallux valgus.