Minimally Invasive Operative Treatment of Bunionette Deformity with Percutaneous Distal Metatarsal Osteotomy
Jin Woo Lee
Woo Jin Choi
Bunionette or “tailor’s bunion” is a painful lateral prominence of the fifth metatarsal head, leading to a chronic bursitis overlying the lateral side of the fifth metatarsal head. Conservative treatment with wide toe box shoes, semirigid shoe inserts, metatarsal pads, metatarsal bars, and stretching of the shoes may relieve the symptoms.1 Operative management is indicated when nonoperative treatments can no longer control symptoms and when the patient has special demands, particularly in sports.1 The indication for performing a percutaneous distal osteotomy is the same as that for performing a distal osteotomy with an open technique. Mild to moderate bunionette deformities may be corrected with this technique. The percutaneous procedure has evolved from the traditional open techniques that depend on stabilization with a Kirschner wire (K-wire) for hallux valgus2, 3, 4, 5 and was standardized by Bösch et al.6, 7 Giannini et al.8 recently presented a new minimally invasive technique of percutaneous distal metatarsal osteotomy, the characteristics of which can be summarized with the abbreviation “S.E.R.I” (simple, effective, rapid, inexpensive), for correction of bunionette deformity.
The patient is placed in supine position on a radiolucent operating table (Fig. 24-1). The foot is kept internally rotated with a small sandbag under the ipsilateral hip. The operation is usually performed using regional anesthesia and a tourniquet is used. Skin preparation and draping is performed with standard technique. Portable C-arm image intensifier television fluoroscopy is necessary to identify the correction of deformity and the pin position.
A lateral incision of 1 cm is made just proximal to the lateral eminence of the fifth metatarsal head through the skin and subcutaneous tissue, down to bone. The soft tissue is separated dorsally and plantarly, and held by two small retractors. The lateral wall of the metatarsal neck is now visualized (Fig. 24-2).
The complete osteotomy usually is made using a small blade oscillating saw from lateral to medial side with the obliquity oriented from plantar proximal to dorsal distal with an angle of approximately 30 degrees (Fig. 24-3). The key points of the technique are the inclinations of the osteotomy in the medial-lateral and dorsal-plantar direction, the displacement of the head in the medial-lateral and dorsal-plantar direction, and the rotation of the metatarsal head according to the types of deformity.8 The plane of the osteotomy in the lateral to medial direction is perpendicular to the fourth ray if the length of fifth metatarsal bone must be maintained. The osteotomy may be directed from distal to proximal up to 25 degrees, if shortening of fifth metatarsal bone is necessary in cases of mild arthritis. More rarely, if a lengthening of the fifth metatarsal bone is necessary the plane of the osteotomy is inclined in a proximal-distal direction approximately 15 degrees.
To control the dorsal translation of the metatarsal head with weight bearing the osteotomy is normally inclined about 30 degrees in distal-dorsal to proximal-plantar directions (Fig. 24-4). The adjustment of the lateral-medial position of the metatarsal head is performed by introducing the K-wire superficial with regard to the lateral eminence. The adjustment of the plantar-dorsal position of the metatarsal head is obtained introducing the K-wire in the upper or lower aspect, with regard to the long axis of the metatarsal head. If supination of the fifth metatarsal bone is present, the correction is obtained with derotation of the lesser toe to the neutral position.