Scarf osteotomy

The scarf osteotomy is an orthopedic surgical procedure with bone transection to correct ( corrective osteotomy ) of misalignments of the first metatarsal bone ( metatarsal 1 osteotomy ). It is often performed in hallux valgus with protruding ball ( metatarsus primus varus ) and is considered a z-shaped diaphyseal osteotomy . An osteosynthesis is usually done with two small screws.

Historical

The first z-shaped diaphyseal osteotomy of the first metatarsal bone was proposed by Meyer as early as 1926, but with a vertical incision. The first description of a horizontal osteotomy of the first metatarsal bone was made in 1976 by JM Buruturan, for an extension of the bone. To correct hallux valgus it was used in Chicago from 1983 by the surgeons Gudas and Zygmunt, and Lowell Weil coined the name "scarf osteotomy" in 1984. After Louis S. Barouk got to know this technique at Weil, he took it over himself and presented the process with Weil in the currently generally accepted form in the 1990s, which made it generally known and popular.

The English name comes from the carpentry trade , where it denotes a form of spanning that is very similar to the displacement of osteotomy fragments and has been used for a long time to lengthen beams.

indication

The most important indication is hallux valgus , in which the accompanying or triggering varus deformity of the first metatarsal is treated. Unlike the chevron osteotomy , the scarf osteotomy is also suitable for more pronounced misalignments with an intermetatarsal angle of up to 40 °. At the same time, the metatarsal shaft can be lengthened or shortened, as well as a rotation of up to 15 °. It is also possible to let the metatarsal 1 head step deeper and thus to put more stress on the first beam. This leads to the relief of the remaining metatarsal rays, which is particularly useful in the case of a painful splayfoot ( metatarsalgia ).

The scarf osteotomy can also be used for hallux varus .

execution

The anesthesia can be peridurally or regionally , also as an intravenous block . As a rule, the operation is performed in a bloodless state . The skin incision is made on the inside in the middle along the shaft of the first metatarsal. First, a Kirschner wire is inserted into the metatarsal head for guidance , before the first step is to make the dorsal-distal short cut at around 50–60 ° with an oscillating saw . This is followed by the long, longitudinal horizontal incision, inclined in the proximal-plantar direction in relation to the shaft axis, which is made parallel to the sole of the foot and ends about 2 cm distal to the first tarsometatarsal joint , followed by the final, proximal plantar short incision at a 60 ° angle to complete the z-shaped osteotomy. The horizontal cut, parallel to the plantar surface, causes the head to step down if it is beveled laterally by about 20 ° plantarward, which can increase the load on the first beam.

The lateral displacement of the distal fragment, including any rotation, shortening or lengthening, can then be carried out by pulling the big toe and using bone clamps. For fixation, two special retractable threaded head screws ( Barouk screws ) are generally inserted from the dorsal under visual control, which bring the osteotomy under compression and thus hold the corrected position. Due to the special technique of the osteotomy, it is inherently self-retaining ( intrinsically stable ), so that originally the scarf osteotomy was performed without any osteosynthesis. Finally, the dorsally protruding bone portions are smoothed.

Additional soft tissue and bony interventions are also carried out on the metatarsophalangeal joint of the big toe:

• Lateral release of the metatarsophalangeal joint of the big toe and the lateral sesamoid bone there
• Medial capsule compression at the metatarsophalangeal joint of the big toe, if necessary with capsule plastic
• Optional cheilectomy , the removal of the medial part of the head, which is prominent as the excess leg ( exostosis ) on the ball of the foot .
• Optional Akin osteotomy as a shortening osteotomy of the basal phalanx of the big toe (the proximal phalanx), predominantly in the presence of hallux valgus interphalangeus.

Aftercare

Wound care with timely suture removal is carried out according to the usual guidelines. In the beginning, elevation, protection and cooling are recommended. Are mostly for pain anti-inflammatory drugs used.

Mobilization usually takes place after one to two days, whereby the big toe has to be moved actively and passively in order to prevent stiffening. Due to the intrinsic stability of the osteotomy, no forefoot relief shoes are usually necessary, except in the case of osteoporosis . Instead, soft shoes or bandage shoes are usually used, and full weight-bearing is usually allowed from the second day after the operation. In most cases, you shouldn't take long walks or exercise for five to six weeks. X-ray checks are often carried out after one and six weeks, when signs of bone healing are usually already visible in the X-ray. A complete swelling and a normal range of motion as before the operation are often only achieved after three to five months.

For the period of relief or incomplete mobility, thrombosis prophylaxis is often prescribed in the form of once daily subcutaneous injections of a low molecular weight heparin (LMWH).

Complications

The overall complication rate is low, but general surgical complications such as wound infection or wound healing disorders are possible. Special complications are:

• Pseudarthrosis , the failure of bone fragments to grow together, is extremely rare and more likely if there is severe lateral displacement.
• Stiffness and decreased big toe mobility.
• Breakage or loosening of the screws are only observed in rare isolated cases.
• Osteonecrosis of the head in about 0.2%, whereby the main blood supply is secured by the plantar and is most likely to be injured in the lateral release . As a result, arthrodesis of the metatarsophalangeal joint of the big toe is usually necessary.
• Soft tissue or tendon irritation due to protruding screw heads is also very rare due to the type of screw with retractable thread-bearing screw heads. Accordingly, material is only removed in rare cases.
• Insufficient correction or relapse
• Overcorrection with hallux varus formation in less than 1% up to 8% of cases. The cause is usually too extensive a lateral release , too much medial capsule compression, too large a cheilectomy or too much displacement of the distal fragment laterally.
• Stress fractures are very rare. A stress fracture can be largely prevented by modifying the osteotomy technique with plantarization of the short proximal incision.

literature

• LS Barouk, LS Weil: Hallux valgus: The scarf osteotomy. In: Nikolaus Wülker et al. (Ed.): Operation atlas foot and ankle. 2nd, revised and expanded edition. Thieme, Stuttgart et al. 2007, ISBN 978-3-13-142592-8 .
• RA Fuhrmann, A. Notni: Diaphyseal osteotomy of the first metatarsal bone in hallux valgus. In: Tomás Epeldegui Torre, Nikolaus Wülker (ed.): Lower leg, ankle and foot (= surgical techniques in orthopedics and traumatology. Vol. 8). Elsevier, Urban and Fischer, Munich 2005, ISBN 3-437-22576-6 , p. 333 ff .: Chapter 46.

Individual evidence

1. ↑ Hans-Jörg Trnka: The Scarf Osteotomy - One Technique for Everyone? Orthopedic News 03/2018, page 20

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