Mastering The Scarf Bunionectomy

Author(s): 
By Lowell Scott Weil Jr., DPM

While the great majority of hallux valgus deformities can be accommodated with a wide toe-box shoe, secondary deformities, such as painful hammer digit syndrome and metatarsalgia, coupled with patient demands, often drive the need for operative intervention. In addition, some individuals are averse to wearing any type of special shoes and wish to have the deformity corrected rather than accommodated. When an operation is indicated in your opinion and in concert with the patient’s wishes, the goals for the ideal hallux valgus operation are as follows: • joint congruity with full, pain-free range of motion postoperatively; • improved cosmesis and the ability to wear varied shoe styles; • minimum postoperative disability and interference with the activities of daily living; and • minimal and salvageable complications. At the Weil Foot and Ankle Institute, performing hallux valgus surgery over the years has taken us through the McBride, Keller, Chevron, crescentic, closing base wedge and Lapidus procedures. Although each of these procedures was successful for the perfect indication, the versatility and predictability for success was not optimal. We have used the Scarf bunionectomy as our primary hallux valgus procedure since 1990. The procedure is versatile, structurally sound, has a wide range of indications and applications, and allows for an early, functional recovery. The surgical technique is not purely an osteotomy but rather a combination of techniques involving a fibular sesamoidal release, Scarf osteotomy, a unique form of rigid internal fixation, capsule-tendon balancing and a rigorous postoperative rehabilitation. Each and every component of this bunionectomy contributes to the success. Key Benefits Of The Scarf Osteotomy The Scarf osteotomy has great versatility as it allows several important benefits, including lateralization of the head-shaft fragment to reduce the IM angle. Unlike the crescentic or proximal Chevron, this lateral displacement does not increase the PASA, thereby maintaining joint congruity and avoiding the long-term complication of arthrosis. Other advantages of the procedure include: • medialization of the capital fragment (in cases of hallux varus); • plantar displacement to increase the first ray load; • dorsal displacement to decrease the ray or tibial sesamoid load; • elongation in cases of a short first metatarsal; • shortening in cases of a long first metatarsal or severe deformity; • transverse plane rotation up to 15 degrees to correct an increased PASA; and • axial rotation (supination) in cases of first metatarsal pronation. The indications for the Scarf osteotomy are: hallux valgus deformity with an intermetatarsal (IM) angle of 12 to 24 degrees, increased PASA and range of motion of the first metatarsophalangeal joint of greater than 40 degrees without severe joint arthrosis. Pertinent Surgical Pearls For The Scarf Osteotomy The Scarf osteotomy is only one of the three components of the Scarf bunionectomy. The first step is releasing the metatarsophalangeal, lateral sesamoidal complex, followed by a Scarf osteotomy of the first metatarsal with supportive and rigid fixation. The final step is medial capsulorrhaphy and capsuloplasty. The addition of a phalangeal osteotomy (Akin or shortening) is commonly performed with the Scarf bunionectomy. You would perform the procedure under a combination of intravenous sedation and local anesthesia. Administer a Mayo block, utilizing 15 to 20 cc of 0.5% bupivicaine, just prior to inflating an ankle tourniquet to 250 mm/hg. Use a medial incision approach where the skin of the plantar surface meets the skin of the dorsum. The length of the incision varies depending on the intended horizontal length of the osteotomy. Identify and preserve the neurovascular structures, and retract the wound edges using four flexible skin hooks. Encircle the foot with the hooks and clamp them laterally. Make a lenticular capsular incision, removing a small ellipse of capsule adjacent to the dorso-plantar midline of the metatarsal head. Then reflect the capsule and periosteum dorsally along the medial side of the metatarsal head and shaft, and distally to the base of the proximal phalange, preserving the dorsal capsule. Your subsequent plantar reflection should expose the joint while preserving the vascular network just proximal to the sesamoids. Then deepen the reflection more proximally via blunt dissection.

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