- Scarf Osteotomy for Hallux valgus correction -Prospective clinical and pedobarographic study

U. Hahn, A. Staemmler, U. Speiser, A. Weber

8th EFORT-Congress11. – 15. May 2007

Florence, Italy

Klinik für Orthopädie und Orthopädische Chirurgie

Städtisches Klinikum Dresden-Friedrichstadt

Akademisches Lehrkrankenhaus der

Technischen Universität Dresden

Chefarzt: Prof. Dr. med. H. Fengler

Introduction

Materials & Methods

Results & Discussion

Pedobarographic and clinical analyses have proved effective in assessing the effects of operative corrections of the forefoot. Before now, post-operative changes in plantar pressure distribution have been verified [1−3].

The data of 50 patients (average age 50.7 ± 13.3 years) with hallux valgus were recorded pre-operatively and on average 18 months postoperatively; these patients were treated with a scarf osteotomy on 55 cases from January 1, 2002 to March 31, 2003. They were compared with a group of 50 test subjects with healthy feet (average age 44.5 ± 14.9 years) who were tested in the same way. As well as the 55 scarf osteotomies, altogether 24 Akin proximal phalanx osteotomies and 48 Weil metatarsal-shortening osteotomies were carried out. Both pre-operatively and in the follow-up, the clinical assessment was effected using the Hallux Metatarsophalangeal Interphalangeal Score from the American Orthopedic Foot and Ankle Society (AOFAS). The subjective assessment of life quality, using the score of Bonney and MacNab, was carried out by the patients themselves. All pedobarographic readings were recorded with the EMED-ST-4 System (NOVEL GmbH, Munich, Germany). The forefoot was divided into six regions (metatarsalia I-V and hallux) and examined for peak pressure, maximum force and as well as pressure- and force-time integrals.

With a maximum AOFAS score of 100 points, a significant improvement in the symptoms was evident in the follow-up (94.1±6.6 points) compared to the pre-operative condition (53.4±16 points). In the subjective assessment, pre-operatively 94.5% indicated that their life quality was satisfactory or bad, in some cases with considerably reduced mobility and constant pain. Post-operatively, on the other hand, 98.2% of patients rated their quality of life as good or very good.Despite a pedobarographic increase of the peak pressure and the pressure-time integral under most of the metatarsalia due to the forefoot correction which had been carried out, the frequency of metatarsalgia was significantly reduced. The reason for this is probably the more uniform pressure distribution, similar to that of a healthy foot, which was achieved by the operative correction, meaning that peak pressure points no longer form. Significant increases in the maximum force were found in all sections tested when comparing pre- and postoperative results. The whole forefoot, in particular the big toe, took part in the rolling movement of the foot with a higher maximum force again, as physiological conditions had been restored and the pathological malpositioning eliminated. The force-time integral was assessed as another biomechanic parameter of the foot;

1. Buchner, M., et al., Druckverteilungsmessung nach Scarf-Osteotomie bei Hallux valgus. Z Orthop Ihre Grenzgeb, 2005. 143(2): p. 233-9. 2. Jones, S., et al., Scarf osteotomy for hallux valgus. A prospective clinical and pedobarographic study. J Bone Joint Surg Br, 2004. 86(6): p. 830-6.3. Kernozek, T.W., A. Elfessi, and S. Sterriker, Clinical and biomechanical risk factors of patients diagnosed with hallux valgus. J Am Podiatr Med Assoc, 2003. 93(2): p. 97-103.

This study looks into clinical and subjective results of scarf osteotomy, as well as aspects of plantar pressure and strength distribution in both the pre- and postoperative conditions compared to a selective control group with healthy feet. Furthermore, it examines the influence of the accompanying Weil metatarsal-shortening osteotomy and the effects of plantar callosity on pedobarographic results.

in the follow-up this showed a significant increase under the medial metatarsalia compared with the pre-operative situation.This is evidence that during walking, after operative intervention the first ray actively takes on weight the same way as in a healthy foot. The analysis of the Weil metatarsal-shortening osteotomy showed a significant lowering of the peak pressure under the affected metatarsals compared with a control group without intervention in the metatarsal heads. Similarly, significantly higher values for all the measurements were verified in patients with symptomatic plantar callosity under the metatarsal heads concerned, compared with a group without callosity or where it was asymptomatic. From this it may be concluded that the symptoms of plantar callosity arise from significantly raised, pathological local peaks of stress caused by the altered biomechanics of the forefoot with hallux valgus. According to the clinical results, the scarf osteotomy proved effective as a tried and tested means for the operative treatment of a hallux valgus.This was proved biomechanically in the pedobarographic results.

Fig. 1 shows the AOFAS-Score in total and in the parts pain, function and alignment. In all sectors the operation leads to a improvement, nearly to the available points.

Fig. 2 shows the pressure-time-integral under the hallux and the metatarsals measured in Ns/cm2 (MT = metatarsals). It comes to an increase of the integral but to more physiological distribution under the metatarsals.

Fig. 3 shows the force-time-integral under the hallux and the metatarsals measured in Ns (MT = metatarsals). The improved postoperative load-bearing function under the metatarsal heads 1 to 4 can be seen, where it is similar to that of a healthy foot.