Bunionette 

Updated: Jun 06, 2018
Author: Christopher Brown, MBBS, FRCSC, FRACS, FAOrthA; Chief Editor: Vinod K Panchbhavi, MD, FACS 

Overview

Background

The term tailor's bunion (a synonym for bunionette) initially described an acquired lesion that caused chronic pain and swelling over the lateral aspect of the fifth metatarsal (MT) head. These lesions often were present on tailors, whose traditional cross-legged sitting posture on benches resulted in pressure being placed on the lateral side of the foot, leading to the development of painful bunionettes. Davies described the lesion in the English literature in 1949.[1]

A bunionette is defined as a painful prominence on the lateral aspect of the fifth MT head. Although it is not as common as a medial bunion, it is a cause of chronic pain and shoe-fitting problems in individuals whose feet are characterized by a widened forefoot or in those who have a lateral splaying or prominence over the fifth MT.[2, 3, 4]

For patient education resources, see Chronic Pain.

Pathophysiology

The underlying pathoanatomy and pathophysiology determine procedure selection. No single, universally acceptable procedure exists for all patients.

The pathoanatomy of the bunionette varies with different types of lesions. Usually, there is a component of prominence of the lateral aspect of the fifth metatarsophalangeal (MTP) joint. Stretching and attenuation of the capsule may occur with medial subluxation of the proximal phalanx. Both long flexors and extensors can be medial to the head, leading to a deforming force on the toe that increases with increasing deformity. Rotation of the phalanx also can occur.

Pathologic lesions include the following:

  • Inflamed bursa overlying the lateral aspect of the MT head
  • Bony enlargement of the head itself
  • Increased intermetatarsal angle (IMA) between the fourth and fifth MTs with secondary medial angulation of the phalanx and abnormal curvature of the fifth MT

The normal fourth and fifth IMA is approximately 6.2°, and the normal fifth-MTP angle is about 10°. Pathologic values are in the range of 10° for the IMA and 16° for the MTP angle. Lesions may be conveniently divided into three types (see Imaging Studies).

Etiology

Causes of bunionette can be extrinsic or intrinsic.[5] Extrinsic causes can be traumatic, either acute or (more commonly) chronic (eg, tailors' working posture, footwear). Intrinsic causes can be related to structural abnormalities, such as congenital lateral bowing of the MT shaft, abnormal intermetatarsal ligament insertion with prominence of the fifth MT, brachymetatarsia, or primary hypertrophy of the MT head. Congenital splayfoot is a more generalized congenital predisposing lesion.

Iatrogenic causes can occur as a result of failed adjacent MT surgery or residual malalignments from hindfoot surgery, which cause increased prominence of the fifth MT. Inflammatory arthropathies also can cause bunionette deformities or soft-tissue lesions in association with bony problems.

Epidemiology

United States statistics

In Western society, the occurrence of bunionettes is related to narrow footwear on predisposed foot anatomy. The actual incidence is not accurately known, but it is far less of an isolated presenting problem than hallux valgus. However, it is commonly seen in patients who present with hallux valgus secondary to splaying of the forefoot. It may or may not be symptomatic at the same time. Females represent up to 90% of symptomatic patients in some series.

International statistics

Few reports exist in the literature on the incidence in non-Western countries. This is probably a result of less wearing of constricting shoes and, hence, a lower occurrence rate.

Prognosis

Relief of pain and imporved alignment usually can be obtained with surgical treatment. When cosmesis is the only reason for surgery, satisfaction is less likely because minor symptoms may persist for some months following surgery. Continuing progression of underlying arthropathic disease also may lead to recurrence and unsatisfactory results.

 

Presentation

History

Presenting symptoms usually include painful keratoses over the lateral aspect of the metatarsal (MT) head, but they also may be present on the plantar and dorsal aspects. Medial deviation of the fifth phalanx with some rotation is frequently seen. Determining whether the patient is truly having pain or whether he or she just finds the foot cosmetically unacceptable is important. Assessing whether the deformity is fixed or correctable also is important.[6]

Physical Examination

Examination should assess other foot deformities, such as hallux valgus, planovalgus foot deformity, and equinus, as well as the presence of neuritic symptoms or systemic arthropathy.

 

Workup

Laboratory Studies

Obtain standard preoperative hematology tests. Investigation of arthropathy or diabetes also may be necessary. Cultures may be obtained for infected lesions. More accurate bacteriologic diagnoses of infected lesions are obtained from operative specimens.

Imaging Studies

Obtain standing weightbearing views of both feet. These films should be recent, especially in rheumatoid and arthropathic cases. Deformities can be classified into three types on the basis of their appearance on plain films, as follows:

  • A type 1 lesion has an enlarged head as an isolated lesion (see the first image below)
  • A type 2 lesion has an abnormal lateral bowing of the fifth metatarsal (MT; see the second image below)
  • A type 3 lesion has a 4-5 intermetatarsal angle (IMA) in excess of the normal 6-8° (see the third image below)
Type 1 bunionette. Note enlarged head without mark Type 1 bunionette. Note enlarged head without marked angulation.
Type 2 bunionette. Note abnormal bowing of metatar Type 2 bunionette. Note abnormal bowing of metatarsal and secondary angulation of metatarsophalangeal joint.
Type 3 bunionette. Note increased angle between fo Type 3 bunionette. Note increased angle between fourth and fifth metatarsals. Angulation at metatarsophalangeal joint is secondary to medial pressure on phalanx.

Attenuation of the intermetatarsal ligament between the fourth and fifth MT shafts usually is found in type 2 and 3 lesions. Type 1 bunionettes with an enlarged head may not have significant capsular attenuation, and they do not necessarily have increased IMAs or even angulation at the metatarsophalangeal (MTP) joint.

In a retrospective comparative study of 112 feet with symptomatic deformity and 123 asymptomatic control feet, Shimobayashi et al described the use of a radiographic image-mapping system to analyze the morphologic characteristics of the entire foot, including forefoot width and splaying of all MTs, rather than focusing solely on the fourth and fifth MTs.[7] They suggested that this broader analytic approach would be useful in planning surgery.

Vascular studies are prudent in patients with questionable vascularity.

Staging

Aside from the pathoanatomic classification (see Imaging Studies), no specific staging classifications for the lesion exist. Some authors have categorized the deformity as either mild or severe, but no indication is given to define the limits used.

 

Treatment

Approach Considerations

Surgery for bunionette is performed when symptoms of an unacceptable degree are not relieved by conservative treatments, such as shaving the callous or wearing wider shoes, silicon pads, softer shoe coverings, or sandals. At present, the appropriateness of minimal incision surgery for management of this condition has not been established, though some percutaneous approaches appear promising.[8, 9, 10] Future developments may include different osteotomies.

Absolute and relative contraindications for surgery include the following:

  • Pure cosmetic deformity
  • Vascular impairment
  • Severe diabetic arthropathy
  • Significant infection with bony involvement
  • Psychiatric disorders that prevent appropriate postoperative compliance
  • Severe osteoporosis
  • Severe progressive erosive arthropathies

Some of these contraindications apply to specific reconstructive procedures. For example, severe refractory deformities, inflammatory conditions, and infected neuropathic arthritic or failed surgical procedures may necessitate treatment with ablative rather than reconstructive procedures.

Medical Therapy

Treatment often can be nonoperative, involving the use of padding, shoe modification with arch supports or orthotic devices, anti-inflammatory medications, and, occasionally, corticosteroid injections into the bursae.

Surgical Therapy

Surgical procedures are determined by the pathoanatomy (see Imaging Studies),[11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21]  as follows:

  • Type 1 lesions can be treated with condylectomy and capsular plication, though this is indicated only in the absence of any evidence of an increased intermetatarsal angle (IMA); it may be associated with a bursectomy or with nodule removal in patients with arthropathy; if the joint is severely arthritic, excision arthroplasty may be performed [22]
  • Type 2 lesions may respond well to a midshaft rotational osteotomy; lateral distal condylectomy can be added if warranted
  • Type 3 lesions of moderate degree may respond to lateral condylectomy and distal metatarsal (MT) osteotomy [11, 23, 24] ; oblique and chevron-type osteotomies are common [12] ; large deformities require a midshaft or proximal osteotomy [25]

These procedures can be performed on an outpatient basis. Assess general fitness for ankle block, popliteal block, or more general anesthesia.

Longitudinal lateral incisions are used with care to avoid injury to branches of the sural nerve. In distal procedures, a distally based capsular flap is created, and the lateral portion of the condyle is exposed. Take care to avoid excessive resection to prevent instability. Intraoperative low-dose fluoroscopy is very useful. If an osteotomy is carried out distally, avoid excessive medial displacement. The neck can be quite narrow, making fixation difficult. Pinning often is needed.

Midshaft osteotomies are best performed by rotating around a screw that is inserted into a partially osteotomized MT. Completion of the osteotomy site is accomplished after the screw is partially inserted. Appropriate sloping of the osteotomy in two planes allows depression and correction of the IMA if needed.

Postoperative Care

Postoperative dressings are used for 6 weeks, with dressings being changed as necessary. Patients with midshaft and proximal osteotomy should be restricted to nonweightbearing ambulation for the full 6 weeks. Patients with more distal osteotomies can bear weight in a postoperative shoe as soon as 3 weeks after surgery.

Complications

Complications include the following:

  • Malunion
  • Nonunion
  • Nerve injury
  • Metatarsophalangeal (MTP) joint pain and stiffness
  • Symptomatic hardware or infection

Recurrence can occur from poor procedure selection or performance or from progression of underlying pathophysiology (eg, arthropathy). Nonunion is a significant risk with proximal MT osteotomy, though it can occur with midshaft osteotomies.

Long-Term Monitoring

Return to normal footwear may take several months. Sporting activities that involve repetitive stresses (eg, basketball) should be delayed for 3 months if an osteotomy has been performed. Checking films to ensure adequate healing is prudent before high-stress activities are allowed.