Patients were satisfied with the results of 107 (91%) of the 118 procedures and dissatisfied with the results of eleven (9%).
With regard to the radiographic findings (Table V), the final first intermetatarsal angle averaged 7.3° ± 2.7° and the hallux valgus angle averaged 13.7° ± 6.7°. The mean distal metatarsal articular angle decreased from 14.2° ± 6.4° preoperatively to 6.7° ± 4.6° at the time of final follow-up. The mean sesamoid position was graded as 0.4 ± 0.6 at the time of final follow-up, compared with 2.0 ± 0.8 preoperatively.
Plantar displacement of the first metatarsal head (mainly a plantar translation, with some degree of plantar angulation in a few feet) was found at the time of follow-up in fifty-eight (49%) of the 118 feet, dorsiflexion of the head (mainly angular deformity) was seen in fourteen feet (12%), and a position that can be defined as neutral (essentially similar to the preoperative position) was observed in forty-six feet (39%).
The extent of lateral displacement of the first metatarsal head was 52.6% ± 20.6% of the diameter of the first metatarsal shaft in the immediate postoperative period and 32.8% ± 18.6% at the time of follow-up.
There was one early deep infection at the osteotomy site, which was treated with intravenous antibiotic therapy and resolved in about two weeks. There was no need to remove the Kirschner wire before the scheduled time. Superficial skin irritation by the Kirschner wire occurred in two feet (1.7%), and permanent numbness of the hallux occurred in three. There were no nonunions of the osteotomy site. One sixty-two-year-old man had progressive recurrence of the deformity with pain and severe limitation of his ability to walk.
Motion of the first metatarsophalangeal joint was limited to <30° in eight feet (6.8%) in seven patients. These patients included one woman who had presented with hallux valgus rigidus preoperatively. At thirty-five months postoperatively, the hallux appeared to be well aligned and was only occasionally painful. This patient's only limitation was the inability to wear high-heeled shoes. One case of rigidity resulted from the above-mentioned early infection, and the other cases were related to poor mobilization of the hallux following removal of the tape. However, these patients did not regard the joint motion deficit as disabling, and the rigidity did not cause pain during walking.
No cases of secondary hallux varus were observed despite the slight overcorrection that had been consistently achieved at the time of stabilization of the osteotomy site.
This study showed that the percutaneous distal osteotomy enables the orthopaedic surgeon to achieve good correction of a moderate hallux valgus deformity, a finding that confirms previously reported results in the literature2,16-18,20. The positive changes in the radiographic parameters measured following consolidation of the osteotomy site fulfill the bio-mechanical requisites for distal osteotomies of the first metatarsal, and the clinical results, which were entirely comparable with the reported outcomes of distal osteotomies performed with open techniques1,3-7,14,15,21,27-32, were maintained at the time of follow-up.
The only true contraindication to this procedure is hallux rigidus with stiffness of the joint and periarticular osteophytes that cannot be fully treated by the percutaneous technique.
The type of fixation is an important element of the surgical technique2,6-8,21. The percutaneous Kirschner wire inserted parosteally in a distal-to-proximal direction at the level of the proximal phalanx and the first metatarsal and then coming to lie in an intramedullary position at the level of the diaphysis appears to be suitable for the stabilization of the osteotomy site. It should remain in place for four weeks.
Consolidation of the osteotomy site was confirmed radiographically in all patients within six months. Good angular correction, comparable with that reported following use of the more standard open techniques3,5,7,14,15,21,28,31, was obtained despite the slight varus hypercorrection at the time of the operation.
The reported rate of deep infection has ranged from 0% to 3.5% in other series in which the percutaneous technique was used16-18,20. Our low rate of one of 118 was related both to the advantages afforded by the minimally invasive procedure and to the thorough standardization of a postoperative monitoring protocol that required a clinical examination with dressing changes and retaping at weekly intervals2,16-20 until the Kirschner wire was removed. This was of fundamental importance for reducing pin-track problems.
Hallux varus hypercorrection was not observed in our series. The fact that, to our knowledge, this complication has never been reported in association with this technique17,18,20 may be due to the avoidance of surgery on the soft tissues, including any type of lateral release of the first metatarsophalangeal joint. Such releases can be avoided because of the substantial lateral displacement of the first metatarsal head afforded by the particular type of Kirschner wire stabilization. The displacement may be as much as 75% to 90% of the transverse diameter of the osteotomy, which brings about a substantial relaxation of the tendon of the adductor hallucis. The lack of soft-tissue surgery does not appear to affect the prevalence of recurrent hallux valgus deformity, perhaps because reorientation of the metatarsal head and reduction of the head on the sesamoids were the consistently achieved primary surgical objectives17.
The lateral displacement of the first metatarsal head achieved at surgery (mean, 52.6%) was not maintained by the time of full consolidation of the osteotomy site (mean, 32.8%). The action of the long extensor and long flexor tendons on the hallux during the plasticity phase of the healing callus probably offset the slight hypercorrection obtained at the time of surgical stabilization.
Stiffness of the first metatarsophalangeal joint is one of the most feared outcomes of hallux valgus surgery and one that affects the overall clinical result. Percutaneous distal osteotomy of the first metatarsal is an extra-articular operation and therefore should have a limited effect on the postoperative range of motion of the hallux. Reduction of the range of motion is therefore most likely due to pre-existing degenerative arthritis or a failure to implement the brief rehabilitation program following removal of the Kirschner wire and the bandage. The Kirschner wire stabilizes the first metatarsophalangeal joint for four weeks, which creates the risk of postoperative stiffness. In the present study, stiffness was by no means rare, with a rate of 6.8% (eight of 118). However, one case resulted from a postoperative infection, and we believe that the other cases were at least partly attributable to poor mobilization after removal of the Kirschner wire. While most of our patients had the same degree of joint motion at the time of follow-up as they had preoperatively, all patients should be informed that hallux valgus surgery may result in some loss of mobility of the first metatarsophalangeal joint7.
The exposed corner of bone along the medial aspect of the first metatarsal shaft usually remodels over time, but it can remain clinically evident for as long as four to six months. This exposed corner has been reported to cause symptoms, requiring percutaneous revision, in 1% to 2% of patients15,16, but this problem was not observed in our series. Creating a slightly oblique osteotomy plane could have contributed to our achievement of a less prominent bone shelf.
The results of this study demonstrate that subcapital distal osteotomy of the first metatarsal with a percutaneous technique and Kirschner wire stabilization under fluoroscopic control, and without soft-tissue surgery, is an effective, reliable method of treating mild-to-moderate hallux valgus deformity. The results appear to be comparable with those reported following traditional open techniques1,3,4,6,7,14,15,21,28-32, and the technique has all of the advantages of a minimally invasive procedure. These advantages include the simplicity of the procedure, the very short operative time, a reduced risk of complications, and the ability to perform the operation with ankle-block anesthesia and without a tourniquet. ▪
A commentary is available with the electronic versions of this article, on our web site () and on our quarterly CD-ROM (call our subscription department, at 781-449-9780, to order the CD-ROM).
Investigation performed at the Department of Orthopaedics, University of Verona, Verona, Italy
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.
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