Commentary & Perspective

Commentary & Perspective on
"Percutaneous Distal Metatarsal Osteotomy for Correction of Hallux Valgus"
by Bruno Magnan, MD, et al.

Commentary & Perspective by
Michael Coughlin, MD, and Jerry S. Grimes, MD*,
Oregon Health Sciences University, Boise, Idaho

In the June issue of The Journal, Magnan et al. report on a group of eighty-two patients (118 feet) in whom a percutaneous distal osteotomy of the first metatarsal was performed for the treatment of mild-to-moderate hallux valgus deformities over a period of five years. The authors describe an operative technique not unlike the Mitchell procedure^1,2. A percutaneous distal and medial approach was used for the osteotomy. Fixation was achieved with a single Kirschner wire that was introduced at approximately 2 to 3 mm from the medial corner of the nail of the great toe and then driven subcutaneously over the medial eminence and into the medullary canal of the first metatarsal to stabilize the osteotomy site. The procedure is accomplished quickly with minimal disruption of soft tissues. Indeed, the procedure completely eliminates the need to perform a medial exostosectomy, a capsulorraphy, or a lateral soft-tissue release, procedures that are traditional in most surgical repairs of hallux valgus.

The authors report an average American Orthopaedic Foot and Ankle Society (AOFAS) postoperative score of 88 points, although the preoperative score was not recorded. While they report a correction of the hallux valgus angle from 31.5° to 13.7° and a correction of the intermetatarsal angle from 12.3° to 7.3°, the method of measurement is not described. The authors evaluated radiographs by using the method of Smith et al. (1984)³, but a much more recent description of the techniques of preoperative and postoperative measurement of hallux valgus deformities has been published⁴. While it is quite believable that the distal metatarsal articular angle was diminished from 14.2° to 6.7° postoperatively, it is not clear whether a center-head method or a shaft measurement was used; differences in these techniques can dramatically affect the angular correction as recorded by the authors.

The authors note that plantar displacement or angulation occurred in 49% of the osteotomies, dorsiflexion occurred in 12%, and a neutral position was achieved in 39%. Likewise, they note that the initial mean lateral displacement at the time of surgery was 53% and that this diminished to 33% at the time of follow-up. This suggests that the instability of the osteotomy and single pin fixation may be the result of some of the loss in correction. This certainly was the experience with the Mitchell osteotomy. The instability of this type of osteotomy, coupled with minimal internal fixation, is a cause for concern. Metatarsalgia and/or formation of lateral intractable plantar keratoses are the most frequently reported complications after a Mitchell procedure. Hawkins et al.¹ reported lateral metatarsalgia in 31% of patients (fifty-nine of 188 cases) who received the Mitchell osteotomy. It would be interesting to know the prevalence of lateral metatarsalgia in this series, and whether or not callus formation occurred.

The authors report a recurrence rate of 2.5% (three of 118 feet) but do not explain their definition of under-correction or recurrence. Since the mean hallux valgus angle at final follow-up was almost 14°, one wonders whether what occurred was true under-correction or if it represented recurrence over time. The authors report mild, asymptomatic malalignment in twenty-seven of 118 feet (23%). It is not clear if they are referring to malalignment in dorsiflexion/plantar flexion, varus/valgus, or rotation. The average osteotomy lost 37% of the original correction achieved during the treatment (52.6% to 32.8% of metatarsal shaft diameter); therefore, it would appear to us that the pin fixation gives marginal stability as far as rotation is concerned and might be less ideal in noncompliant patients.

Techniques of minimal incision surgery of the first ray have been described previously⁵. Weil⁶ described the birth, end, and rebirth of minimal incision surgery in the podiatric community over a three-decade period of time. Complications have included tendon, vascular, and nerve injuries. In the current report, the authors observed only three patients with numbness of the hallux. Magnan et al. are to be commended for the low rate of postoperative complications.

Despite our concerns, the authors report that patient satisfaction exceeded 90%. The minimal dissection technique obviously reduced the prevalence of osteonecrosis of the first metatarsal head; no cases were seen at the time of the two-year follow-up.

While the reported results are remarkably good for this percutaneous osteotomy with minimal internal fixation, we would caution the reader that Dr. Magnan and his associates have a great deal of experience with this type of technique and that the inherent risks with minimal incision surgery have been well documented⁶. We await with interest the longer-term and prospective reports on this innovative technique.

*The authors did not receive grants or outside funding in support of their research or preparation of this manuscript. They did not receive payments or other benefits or a commitment or agreement to provide such benefits from a commercial entity. No commercial entity paid or directed, or agreed to pay or direct, any benefits to any research fund, foundation, educational institution, or other charitable or nonprofit organization with which the authors are affiliated or associated.

References

1. Hawkins FB, Mitchell CL, Hedrick DW. Correction of hallux valgus by metatarsal osteotomy. J Bone Joint Surg. 1945;37:387-94.
2. Mitchell CL, Fleming JL, Allen R, Glenney C, Sanford GA. Osteotomy-bunionectomy for hallux valgus. J Bone Joint Surg Am. 1958;40:41-60.
3. Smith RW, Reynolds JC, Stewart MJ. Hallux valgus assessment: report of research committee of American Orthopaedic Foot and Ankle Society. Foot Ankle. 1984;5:92-103.
4. Coughlin MJ, Saltzman CL, Nunley JA. Angular measurements in the evaluation of hallux valgus deformities: a report of the ad hoc committee of the American Orthopaedic Foot and Ankle Society on angular measurements. Foot Ankle Int. 2002;23:68-74.
5. de Prado M, Ripoll PL, Golano P. Cirugía percutánea del pie: tecnicas quirurgicas, indicaciones, bases anatomicas. Barcelona: Masson; 2003.
6. Weil LS. Minimal invasive surgery of the foot and ankle. J Foot Ankle Surg. 2001;40:61.

Copyright © 2005 by the The Journal of Bone and Joint Surgery, Inc.