5 Fifth Metatarsal Osteotomy for Bunionette Deformities Abstract: A tailor’s bunion or bunionette deformity is a combination of an osseous and soft-tissue bursitis located on the lateral aspect of the fifth metatarsal (MT) head, and is a condition caused by splaying of the fifth MT. Many different techniques exist for bunionette correction, while the ideal treatment is still debatable. Developed for hallux valgus correction, the SERI technique exhibits a high versatility and efficacy and can easily be applied to the treatment of bunionette with minimal morbidity for the patient and with easy and durable results. A good correction is easily provided through a minimal incision and with the use of a single K wire, to be removed after 4 weeks, for osteotomy stabilization. The procedure is able to correct even major deformities by medially shifting the MT head, and a contact of less than 1 mm is needed between the MT head and the MT bone to obtain a safe consolidation. After a learning curve, no technical problems are to be expected during surgery, as well as a very limited number of minor complications following surgery. Keywords: bunionette, Tailor’s bunion, fifth metatarsal osteotomy, mini-invasive, linear distal osteotomy A tailor’s bunion or bunionette deformity is a combination of an osseous and soft-tissue bursitis located on the lateral aspect of the fifth metatarsal (MT) head, and is a condition caused by splaying of the fifth MT.1 The condition often presents with hallux valgus deformity and is characterized by a flexible splayfoot. Several prospective studies indicate that the condition is 3 to 10 times more common in women than in men, but the incidence and prevalence remains unknown.2 Many different techniques exist for bunionette correction. Weil’s osteotomy, scarfette, and lateral cheilectomy in cases with minimal deformity have been advocated, while the ideal treatment is still debatable.3 Surgical treatment for bunionette should be simple, effective, rapid, and inexpensive (SERI). Developed for hallux valgus correction, the SERI technique is not a new technique because it uses an osteotomy and a stabilization method already described.4,5 The osteotomy, in fact, is a linear distal osteotomy performed immediately before the MT head, as described by Hohmann, Wilson, and Magerl, through a minimal incision and stabilized by a single K-wire, as suggested by Kramer and by Bösch. Nevertheless, it exhibits a high versatility and efficacy given that it is a combination of the strength of these previously described procedures, resulting in a technique with unique characteristic of mini-invasivity, simplicity, versatility, and good stability of the construct. This technique can easily be applied to the treatment of bunionette with minimal morbidity for the patient and with easy and durable result.4 • The main indication for bunionette correction is for pain relief, if painful callosities and reactive overlying bursa persist despite shoe modifications. • Any bunionette, despite the degree of severity, may be corrected by SERI. This technique is particularly useful for the treatment of type 2 and 3 bunionettes where isolated shaving of the lateral eminence would remove a substantial portion of the head resulting in metatarsophalangeal (MTP) joint instability. • Even if mild arthritis is evident, SERI may be performed, taking care to slightly incline the osteotomy in distal-proximal way, shortening the MT, and decompressing the metatarsophalangeal joint. • A tailor’s bunion or bunionette deformity is a combination of an osseous and soft-tissue bursitis located on the lateral aspect of the fifth MT head. • The fifth MTP and fourth and fifth inter-MT angles significantly increase as a result of rotational movement of the fifth ray at its articulation with the cuboid. The fifth ray excessively pronates, leading to a progressive deformity that is accompanied by the fifth toe developing an adductovarus position.3,6 • Pain is generally located over the lateral forefoot, corresponding to the lateral condylar process of the head of the fifth MT which protrudes laterally. This is often associated with a bursitis, which can also be painful as it rubs against the side of a shoe. The forefoot is generally splayed. Fifth toe range of motion in plantar-dorsiflexion should be assessed, as well as the presence of pain during this maneuver. • Coughlin distinguished three types of bunionette: • Because the condition is often present with hallux valgus deformity, the presence of hallux valgus should be also considered. • An anteroposterior (AP) and lateral weight-bearing radiographs of the standing patient are generally enough for a bunionette deformity and permit to effectively plan the surgery. • Computed tomography (CT) or magnetic resonance imaging (MRI) is needed only in cases in which the diagnosis is uncertain. • Footwear modifications. • The presence of stiffness and/or arthritis of the fifth MTP joint of high degree. • Skin ulceration or infection. • Peripheral vascular disease. • The goal of distal osteotomies is to correct all the altered parameters typical of the bunionette, such as fifth MTP angle and the IMA and, furthermore, to derotate the MT head in order to address the supination of the toe or to reduce concomitant stiffness by shortening the MT bone. • A good correction is easily provided through a minimal incision. The procedure is able to correct even major deformities by medially shifting the MT head, and a contact of less than 1 mm is needed between the MT head and the MT bone to obtain a safe consolidation. • Minimally invasive: no soft-tissue procedures, no opening of the capsule, or bursa removal. The whole procedure is made through a less than 1-cm access, under direct visual control. (Intraoperative X-rays are only needed during the learning curve). • Straightforward: the entire procedure takes a very limited surgical time. • Inexpensive: the stabilization of the osteotomy is obtained by a single K-wire, easy to remove after 1 month, during medication. • Up to 1-cm incision just proximal to the MT head. • Do not open the joint or the capsule. • Make the osteotomy immediately proximally to the MT head. • Incline the osteotomy in a dorsal to plantar direction of about 15 degrees to control the dorsal translation of the MT head with weight-bearing. • Take care to make the osteotomy in the lateral to medial direction perpendicular to the fourth ray if the length of fifth MT bone was to be maintained (Fig. 5.1). • Incline the osteotomy in a distal-proximal direction up to 25 degrees if a shortening of the fifth MT is needed (a lengthening is usually not required). • Stabilize with a 1.6-mm K-wire, inserted from proximal to distal.
5.1 Overview
5.2 Indications
5.2.1 Pathology
5.2.2 Clinical Evaluation
Type 1, which has an enlarged fifth MT head and prominent lateral condyle (16–33%).
Type 2, which has a laterally bowed deformity of the fifth MT inducing symptomatic prominence of the lateral condyle (10%).
Type 3, which is characterized by an increased fourth and fifth intermetatarsal angle (IMA) (normal angle, < 12 degrees) with no particular distal fifth MT deformity (57–74%). There may be associated, usually congenital, fifth toe varus overlap, in infraductus or supraductus.7
5.2.3 Radiographic Evaluation
5.2.4 Nonoperative Options
5.2.5 Contraindications
5.3 Goals of Surgical Procedure
5.4 Advantages of Surgical Procedure
5.5 Key Principles
Musculoskeletal Key
Fastest Musculoskeletal Insight Engine
