Paul Hamilton and Sam Singh
SURGICAL MANAGEMENT
The primary indication for a Scarf osteotomy is symptomatic hallux valgus deformity with an intermetatarsal angle of less than 20 degrees. The first metatarsocuneiform joint should be stable. It is a versatile osteotomy that can allow shortening, lengthening, rotation, displacement, or plantarization of the first metatarsal head. Thus, indications include symptomatic hallux valgus with or without mild transfer symptoms, juvenile hallux valgus with an abnormal distal metatarsal articular angle, arthritic hallux valgus not severe enough for a fusion, and revision surgery in suitable cases.
Preoperative Planning
AP and lateral weight-bearing radiographs of the foot are evaluated for metatarsal length, intermetatarsal angle, hallux valgus angle, distal metatarsal articular angle, and interphalangeal angle for cases that may require a proximal phalangeal osteotomy to obtain complete correction. Congruency of the joint, presence of osteophytes, the size of the bony medial eminence, and position and condition of the sesamoids are noted.
Positioning
Surgery is performed on an outpatient basis.
Prophylactic antibiotics are administered.
A thigh tourniquet is applied.
The patient is positioned supine with a sandbag under the ipsilateral buttock so the big toe points to the ceiling.
TECHNIQUES
SOFT TISSUE RELEASE AND BUNIONECTOMY
Approach the metatarsal through a medial longitudinal incision extending from the first tarsometatarsal joint to the medial flare of the proximal phalanx (TECH FIG 1A). This can be extended distally if a phalangeal osteotomy is required. Identify the dorsal medial cutaneous nerve and incise the medial capsule sharply in a single longitudinal direction. Expose the medial eminence and resect it 1 mm medial to the sagittal sulcus (TECH FIG 1B). Overresection can lead to a postoperative varus deformity. Expose the metatarsal shaft using subperiosteal sharp dissection, taking care to protect the plantar neck vascular bundle to the metatarsal head (TECH FIG 1C). The proximal plantar exposure can be performed safely without any disruption to the plantar blood supply. Use a large Langenbeck retractor to protect and retract the plantar flap. The tarsometatarsal joint is identified but does not need to be exposed.
Perform a lateral release of the first metatarsophalangeal joint by exposing the first web space with aid of a lamina spreader as an “over the top” technique. This does not compromise the plantar blood supply. Use a banana blade to perform the sharp dissection (TECH FIG 1D). Release the tendinous insertion of the adductor hallucis muscle onto the fibula sesamoid and proximal phalanx. Release the suspensory metatarsal–sesamoid ligaments and make multiple sharp perforations in the lateral capsule at the joint line if required. Apply a varus force to the hallux, completing the capsular release (TECH FIG 1E).
This release can also be performed through a separate first web space incision if preferred.
TECH FIG 1 • A. The incision is made from the tarsometatarsal joint to the base of the phalanx. B. Resection of the medial eminence. (continued)
TECH FIG 1 • (continued) C. Plantar exposure protecting vascular supply to metatarsal head. D. First web space exposure and adductor release using a Banana blade. E. Varus force is applied to complete lateral release.
SCARF OSTEOTOMY
Make the cut starting with the medial longitudinal cut. This is begun distally 5 mm from the articular surface and 2 to 3 mm from the dorsal surface of the metatarsal and finished 5 mm from the tarsometatarsal joint, 2 to 3 mm from the proximal plantar surface of the metatarsal (TECH FIG 2A). Make the longitudinal cut in the same plane as the plantar orientation of the metatarsal (TECH FIG 2B). This allows a degree of plantarization of the metatarsal head. Using a large Langenbeck retractor helps to visualize the plantar metatarsal surface. Perform the transverse cuts at 60 degrees to the longitudinal cut as a chevron. Both cuts are directed proximally, avoiding convergence laterally, which would hinder translation (TECH FIG 2C). When performing the distal cut, elevate the hand to complete the lateral cut (TECH FIG 2D). Separate the two fragments, taking care not to lever the fragments. These steps may need to be repeated if there has been failure to complete all the cuts, but take care to avoid double cutting. Release of the capsule from the lateral side may be needed if it is preventing displacement (TECH FIG 2E).
TECH FIG 2 • A. Position of the osteotomy. B. Longitudinal cut in the same plane as the plantar metatarsal surface. (continued)
TECH FIG 2 • (continued) C. Transverse cuts, avoiding convergence. D. The hand is elevated to complete the distal transverse cut. E. Release of the capsule from the proximal end.
Perform displacement or rotation with guidance from preoperative radiographs by using a clamp on the distal lateral cortex (TECH FIG 3A). Use a compression clamp to hold the displacement (TECH FIG 3B). Up to two thirds of lateral displacement can be obtained while maintaining a strong lateral strut and good bone apposition.
Obtain screw fixation using Barouk screws (Depuy, Warsaw, IN). These are cannulated, self-tapping screws with a long distal thread and a threaded head to allow compression and burial of the head. Place the distal screw first. Pass the guidewire from the proximal fragment obliquely into the head (TECH FIG 4A). Directly visualize the guidewire in the joint, and withdraw it to be flush with the articular surface so that it can be measured (TECH FIG 4B). A screw at least 4 mm less than the measured amount is used to avoid intra-articular penetration. During the drilling over the guidewire, ensure that the drill countersink is seated fully to avoid inadvertent fracture of screw placement (TECH FIG 4C). Directly inspect the joint. Compress the osteotomy further with the clamp. Place the second guidewire for the proximal screw in the midline in an oblique direction to reach the plantar cortex of the distal fragment (TECH FIG 4D). Measure it by withdrawing the guidewire so as to be flush with the cortex. Retraction of the plantar tissue protects and allows direct visualization of the wire and the drill. This screw length equals the measurement from the wire. Directly visualize the screw to confirm compression and length (TECH FIG 4E).
TECH FIG 3 • A. Method of displacement of the fragment. B. Compression clamp applied after displacement.
TECH FIG 4 • A. Distal wire placement. B. Distal wire position in metatarsal head. C. Seating of distal drill over wire. D. Proximal wire placement. E. Screw length and compression checked.
Resect the medial distal aspect of the dorsal fragment (TECH FIG 5) and check the osteotomy for stability.
Imbricate the medial capsule with a strong absorbable suture while holding the hallux in a neutral or slightly abducted position with the aid of a swab (TECH FIG 6).
Confirm the reduction in the intermetatarsal angle, screws, and relocation of the sesamoids with image intensification with the foot flat on the image intensifier (TECH FIG 7). Assess the need for a proximal phalangeal osteotomy.
Close the wound in layers with continuous Monocryl to skin and apply a forefoot bandage to maintain the correction.
TECH FIG 5 • Residual medial bony protuberance excised.
TECH FIG 6 • Capsule sutured in slightly abducted position.
TECH FIG 7 • A. Image intensifier radiographs taken on table with foot “weight-bearing” image intensifier plate. B, C. AP, oblique, and lateral radiographs of a scarf osteotomy.
POSTOPERATIVE CARE
If safe, patients are discharged home on the day of surgery with strict advice to elevate the foot whenever resting for the first 2 weeks.
In most cases they are allowed to bear weight on their heel and lateral forefoot in a hard-soled postoperative shoe.
Cast immobilization is not required.
The wound is inspected at 2 weeks, at which time the hallux is restrapped and patients are taught simple passive and active toe flexion–extension exercises.
At 5 weeks postoperatively the osteotomy is assessed with radiographs. If there is some consolidation at the line of the osteotomy the patient is instructed to wear a wide shoe or sneaker and to progress to full weight bearing as tolerated. Strapping of the hallux is discontinued at this time. Delayed union or nonunion is rare with this osteotomy.
OUTCOMES
The Scarf osteotomy is now a widely used method of correction for hallux valgus; it is particularly popular in Europe. Satisfaction rates range from 88% to 92%,2,3,8,9 equivalent to those of the chevron osteotomy,4,5 including patients defined as having severe hallux valgus. In a review of five recent publications4,6,8–10 the hallux valgus angle was improved on average by 16 degrees (range 11 to 21), the intermetatarsal angle by 6.4 (range 3 to 10), and the AOFAS score by 45 (range 37 to 55).
A learning curve for performing the Scarf osteotomy has also been noted, with higher complication rates seen in early series.1
COMPLICATIONS
The main complication seen is stiffness, which occurs in up to 5% of cases.7 Other complications include wound problems, infection, undercorrection, overcorrection, fractures, chronic regional pain disorder, and deep vein thrombosis. Delayed union and osteonecrosis are rare complications. Fracture risk can be reduced by preserving the lateral strut when placing the proximal screw and by using a long longitudinal cut.
REFERENCES
· Barouk LS, Barouk P. The Scarf first metatarsal osteotomy in the correction of hallux valgus deformity. Interact Surg 2007;2:2–11.
· Berg RP, Olsthoorn PG, Pöll RG. Scarf osteotomy in hallux valgus: a review of 72 cases. Acta Orthop Belg 2007;73:219–223.
· Crevoisier X, Mouhsine E, Ortolano V, et al. The Scarf osteotomy for the treatment of hallux valgus deformity: a review of 84 cases. Foot Ankle Int 2001;22:970–976.
· Deenik AR, Pilot P, Brandt SE, et al. Scarf versus chevron osteotomy in hallux valgus: a randomized controlled trial in 96 patients. Foot Ankle Int 2007;28:537–541.
· Deenik A, van Mameren H, de Visser E, et al. Equivalent correction in Scarf and chevron osteotomy in moderate and severe hallux valgus: a randomized controlled trial. Foot Ankle Int 2008;29:1209–1215.
· Garrido IM, Rubio ER, Bosch MN, et al. Scarf and Akin osteotomies for moderate and severe hallux valgus: clinical and radiographic results. Foot Ankle Surg 2008;14:194–203.
· Hammel E, Abi Chala ML, Wagner T. Complications of first ray osteotomies: a consecutive series of 475 feet with first metatarsal Scarf osteotomy and first phalanx osteotomy. Rev Chir Orthop Reparatrice Appar Mot 2007;93:710–719.
· Jones S, Al Hussainy HA, Ali F, et al. Scarf osteotomy for hallux valgus: a prospective clinical and pedobarographic study. J Bone Joint Surg Br 2004;86B:830–836.
· Lipscombe S, Molly A, Sirikonda S, et al. Scarf osteotomy for the correction of hallux valgus: midterm clinical outcome. J Foot Ankle Surg 2008;47:273–277.
· Perugia D, Basile A, Gensini A, et al. The scarf osteotomy for severe hallux valgus. Int Orthop 2003;27:103–106.