Scarf Osteotomy

Andy Molloy and Lyndon Mason

Abstract

Burutaran first described the Z first metatarsal diaphyseal osteotomy for correction of metatarsus primus varus in hallux valgus deformities in four cases in 1976. Since then, the procedure has been refined and subsequently popularized internationally through the work of Barouk in France and Weil in the United States. The sagittal Z cut is based on a carpentry technique to longitudinally join two pieces of lumber called a scarf junction. In hallux valgus correction, this technique allows for accurate lateral translation of the first metatarsal to correct the deformity utilizing an inherently stable osteotomy. The diaphyseal location allows for rigid two-screw fixation, allowing for early weight-bearing ambulation. This chapter reviews the surgical technique of performing this procedure, giving tricks to optimize outcome and avoid complications.

Keywords: scarf, metatarsal osteotomy, sagittal Z cut, hallux valgus

10.1 Indications

• Hallux valgus without significant first tarsometatarsal instability.

• Hallux valgus deformity with or without a high distal metatarsal articular angle.

• Hallux valgus without arthritic changes.

10.1.1 Clinical Evaluation

• Although the scarf osteotomy is a highly versatile procedure for hallux valgus correction, it is important to have a number of other procedures in your arsenal to treat the myriad of hallux valgus deformities that can present.

• It is important to assess the stability of the tarsometatarsal joint (TMTJ), as a corrective distal or shaft osteotomy may struggle to correct or prevent recurrence in an unstable TMTJ.

• Arthritis in the first metatarsal phalangeal joint should be assessed. A positive midrange grind test should make you consider fusion surgery rather than an osteotomy.

• Consider the alignment of the entire limb. A pes planus deformity and supinated forefoot will exacerbate the deformity.

• Assess any lesser toe deformities. Firstly, these may require concurrent corrections. Secondly, a metatarsus adductus deformity with lateral deviated lesser toes can prove to be a significant challenge when correcting the hallux valgus deformity.

10.1.2 Radiographic Evaluation

• Weight-bearing anteroposterior, oblique, and lateral radiographs should be obtained.

10.1.3 Nonoperative Options

• The nonoperative options for a hallux valgus deformity aim to reduce the symptoms rather than the deformity itself. Modification of shoes by stretching constricting areas or relieving pressure areas may relieve symptoms. This can be achieved with commercially available ring shoe stretchers or by inserting additional material. Wider footwear with a roomy toe box may afford significant reduction in discomfort related to static forefoot abnormalities. However, the forefoot/hindfoot mismatch can be difficult to manage with off-the-shelf footwear, and custom-made shoe wear can resolve this.

• The use of pads, arch supports, and various insoles may assist in reducing a hallux valgus deformity if associated with a supinated forefoot.

• There is no evidence to support the use of any type of splint or brace and even very little for the long-term success of orthotics. Physiotherapy to stretch the lateral tissues will not reverse the problem but may help ease the pain and stiffness that is felt.

10.1.4 Contraindications

• Osteoarthritis.

• TMTJ instability.

• A narrow first metatarsal, meaning that maximum translation will be insufficient to correct the deformity.

• Severe hallux valgus deformity.

10.2 Goals of Surgical Procedure

• Our overall goal is to improve symptoms and decrease deformity. To be more specific, we aim to achieve a bony correction in order to balance the soft tissues to allow normal function to the hallucal metatarsal articulation.

10.3 Advantages of Surgical Procedure

• The scarf osteotomy is the “workhorse” procedure for the majority of hallux valgus reconstruction. It has great versatility given that it can be used to not only provide lateral shift of the first metatarsal, but also lower or elevate the metatarsal head, lengthen or shorten the first metatarsal, and even provide axial rotation.

• A survey of Australian orthopaedic surgeons found that greater than 50% would perform a scarf osteotomy for moderate to severe hallux valgus deformities.¹

• A scarf osteotomy preserves the blood supply to the metatarsal head due to its long plantar limb.

10.4 Key Principles

• Lateral release.

• Lateral translation of metatarsal head to allow sesamoid coverage.

• Distal soft-tissue realignment.

10.5 Preoperative Preparation and Patient Positioning

• When assessing for appropriateness for scarf osteotomy, it is imperative to measure the width of the metatarsal head. A scarf osteotomy can only reliably translate the distal metatarsal 50% of the width of the metatarsal head, and therefore, if the intended correction is greater than this, another option should be considered (Fig. 10.1).

• Measure the medial and lateral walls of the proximal phalanx. If the length of the medial wall is more than 5 mm than that of the lateral wall, consider an Akin osteotomy (Fig. 10.2).

• Plan the transverse limbs of the osteotomy by drawing on the anteroposterior radiograph the proposed osteotomy 90 degrees to the second metatarsal. This is to ensure that minimal shortening occurs when translation is performed (Fig. 10.2). This can be used to choose an anatomical landmark to aim for the distal transverse cut. This is usually at the fourth metatarsophalangeal joint (MTPJ).

Fig. 10.1 Preoperative and 6-month post-operative radiographs of a hallux valgus correction showing a metatarsal head width measurement and intended correction measurement. Because it is only consistently possible to translate the metatarsal head by 50%, another option for correction should be considered if the intended correction measurement is greater than 50% of the metatarsal head width. In this example, the intended correction measurement is ideal for a scarf.