The development of inflammation, an enlarged bursa, or a callus over a prominent fifth metatarsal head may lead a physician to diagnose a bunionette (Fig. 17-2). Just as bunions can present with differing magnitude and different characteristics, so too can a bunionette.¹ A bunionette may appear radiographically as an enlarged fifth metatarsal head (type I). A flare in the metaphysis may cause outbowing of the fifth metatarsal (type II), leading to symptoms, or a widened 4-5 intermetatarsal angle (type III) characteristic of a splayfoot may lead to pain and callus formation (Fig. 17-3).

Figure 17-2 Bunionette with enlarged bursa.

From Mann RA, Coughlin MJ: In Surgery of the foot and ankle, St Louis, 1993, CV Mosby, p. 443.

Figure 17-3 (A) Bunionette with enlarged fifth metatarsal head. (B) Bunionette with bowing of metaphysic. (C) Bunionette with enlarged 4-5 intermetatarsal angle.

Initially an athlete may complain of pain directly lateral over the fifth metatarsal head, but the examiner should be aware of plantar symptoms as well. Neuritic symptoms involving the fifth toe may occur because of pressure over the lateral digital nerve to the fifth toe. The athlete may note complaints of inflammation, blistering, ulceration, or infection.

On physical examination, the aforementioned complaints usually are obvious. Significant callus formation may be observed on the lateral, plantar, or in a lateral plantar position overlying the fifth metatarsal head. Any pronation of the longitudinal arch should be noted, as well as any restriction in hindfoot motion.

Radiographic evaluation may demonstrate an enlarged metatarsal head, outflaring of the fifth metatarsal metaphysis, or widening of the 4-5 intermetatarsal angle. Widening of the 4-5 angle is the most common. Abduction of the fifth toe in relation to the fifth metatarsal head also may be demonstrated.

Conservative treatment

Early treatment involves attempting to relieve pressure on the underlying bony prominence. Stretching of shoes or obtaining shoes with a soft upper that is more forgiving will relieve overlying pressure. Seams or stitching directly over the bunionette should be avoided. Moleskin applied to a blister may promote healing and protect the area while athletes continue their activities. Altering running and/or training activity also may diminish symptoms. Nonimpact activities such as stationary cycles or swimming can be integrated into the training program. A reduction in total miles per day and per week may be required. Trimming the callus may significantly relieve symptoms. Physicians may teach their patients how to pare the callus appropriately. The callus is shaved in thin layers with the scalpel parallel to the toe. A pumice stone also may be used to pare down the callus. A pumice stone is safer and often more acceptable to patients for home use than a scalpel.

When athletic activity is significantly impaired after conservative efforts, surgical intervention may be contemplated (see Case Study 1). The type of osteotomy selected is dependent on the location of the callosity because specific osteotomies of the fifth metatarsal are oriented to redirect the metatarsal in different directions. Surgical intervention in treating forefoot callosities should be tailored to the patient. Extensive soft-tissue stripping, unsecured osteotomies, and multiple metatarsal osteotomies all should be avoided in athletes. Although a surgical procedure may relieve the painful callosity, athletic performance of the patient may be diminished and thus surgery may be considered unsuccessful. The two surgical procedures presented here fulfill the requirements of exposing the patient to less extensive surgery, use internal fixation, and appear better suited to athletes. Again, when possible, conservative treatment should be advocated by the treating physician until it obviously is incompatible with continued athletic function.

Case Study 1

A 30-year-old skier developed pain and swelling over the plantar lateral aspect of the fifth metatarsal head. An increased callosity was observed over the plantar lateral aspect of the bunionette. A painful, inflamed bursa developed during the middle of ski season that was partially relieved by grinding down the inner aspect of the ski boot overlying the bunionette. Likewise, the area overlying the fifth metatarsal head was relieved in the athlete’s everyday footwear by stretching the leather surface.

On physical examination, a normal neurologic and vascular examination was noted. Prominence of the fifth metatarsal head was characterized by a callosity on both the plantar and lateral aspect. Radiographic evaluation demonstrated an enlarged fifth metatarsal lateral condyle (Fig. 17-4, A).

Conservative care, stretching of shoes, and padding all were recommended.

At the end of ski season, the patient requested surgical treatment because of continued symptoms. An oblique osteotomy was performed and fixed with screws. At 8 weeks following surgery, the osteotomy was healed and the patient began progressive walking that evolved over the ensuing 2 months to jogging and sports activities. Figure 17-4, B shows the correction obtained. The patient skied the following season without symptoms.

Figure 17-4 Case study 1. (A) Bunionette preoperative x-rays. (B) Follow-up x-rays demonstrating correction.

Surgical Treatment

1 The foot is cleansed and draped in the routine fashion. An Esmarch bandage is used to exsanguinate the foot. The ankle is padded carefully and the Esmarch is used as a tourniquet.

2 A longitudinal lateral incision is centered directly over the bunionette, extending from the midproximal phalanx to 1 cm above the metatarsal head. Care is taken to protect the neurovascular bundles.

3 The MTP capsule is detached on the dorsal and proximal aspect and turned downward, exposing the prominent lateral condyle (Fig. 17-5).

4 A sagittal saw is used to resect the lateral condyle in line with the diaphyseal shaft of the fifth metatarsal. (At this point, a decision must be made regarding the type of osteotomy to be performed. For a pure lateral callus, a chevron osteotomy is performed. For a combined plantar lateral callus, a distal oblique osteotomy is performed.)

5A Chevron osteotomy^2,³—A lateral to medial drill hole is placed in the center of the fifth metatarsal head, marking the apex of the chevron osteotomy. A 60-degree angled osteotomy based proximally is directed in a lateral to medial plane. The metatarsal head is translated medially and fixed with a percutaneous 0.045 K-wire (Fig. 17-6).

5B Distal oblique osteotomy^4,⁵—After exposing the metatarsal head and metaphysis, an oblique osteotomy is performed from a distal lateral to proximal medial direction. The metatarsal head is displaced medially and slightly proximally and is allowed to “raise up” approximately 3 mm to decrease plantar pressure beneath the fifth metatarsal head. The osteotomy is fixed with one or two percutaneous 0.045 K-wires (Fig. 17-7).

6 Any remaining prominent metaphysis is shaved with the sagittal saw. A drill hole is placed in the dorsal proximal metaphysis, and the capsule is anchored with an interrupted suture. Remaining interrupted sutures are placed to reinforce the capsular repair (Fig. 17-8).

7 The skin is closed in a routine fashion. A gauze and tape dressing is applied and changed on a weekly basis. The patient is allowed to ambulate in a wooden-soled shoe.

Figure 17-5 An L-shaped capsular incision is used to approach the bunionette.

Figure 17-6 (A) A drill hole is placed in the center of the metatarsal head and drilled in a lateral to medial direction. (B) A chevron-shaped osteotomy is based proximally with the apex at the drill hole. (C) Medial translation of the metatarsal head with K-wire fixation and shaving of the metaphyseal flare (shaded area denotes shaved bone in metaphysic).

Figure 17-7 Distal oblique osteotomy with K-wire fixation (shaded area denotes shaved bone in metaphysic).

Figure 17-8 L-shaped capsular closure. The dorsal proximal corner may be fixed with a drill hole in the metaphysic to anchor the repair.

Athletic activity is increased as swelling and pain diminish. Radiographic confirmation of healing should be present before aggressive activity such as jogging, running, or jumping is commenced. In general, a patient can return to nonimpact activities at 2 months. Limited-impact activities such as jogging are permitted at 3 months. Full-contact/impact activities can be resumed at 4 months, depending on radiographic evidence of healing.

In general, resolution of the symptomatic bunionette can be achieved with one of the above procedures for type I or type II bunionettes. With a splayfoot and a significantly wide 4-5 metatarsal angle, a diaphyseal midshaft osteotomy may be necessary to achieve more correction.⁶ More extensive procedures such as this should be reserved for athletes with significant limitations, because the extensive nature of this surgery may limit postoperative athletic expectations.

Intractable Plantar Keratoses

The development of a keratosis beneath one or more of the metatarsal heads is referred to as an intractable plantar keratosis or IPK. A callosity beneath the fifth metatarsal when associated with a bunionette already has been discussed. A callus may be a localized discrete lesion or a diffuse keratotic buildup (Fig. 17-9). Callus formation in athletes is not uncommon, and if asymptomatic rarely requires medical intervention. With significant buildup, painful symptoms may occur, requiring evaluation and treatment.

Figure 17-9 (A) Discrete callus in a tennis player with an enlarged fibular condyle. (B) Diffuse callus in a runner.

Courtesy Roger A. Mann, MD, and Michael J. Coughlin, MD.

A diffuse callus may be due to repetitive abrasion associated with athletic activity. It also may be associated with a long second metatarsal or a long second and third metatarsal. A discrete callus may occur beneath a single metatarsal head.⁷ It typically is associated with an enlarged fibular metatarsal condyle. It is important to distinguish this from a wart (Fig. 17-10). Although warts (plantar verrucae) typically are not found beneath a metatarsal head, on occasion they can occur in this region and thus must be differentiated from an IPK. Trimming of a wart will uncover end arterioles in the lesion characterized by punctuate hemorrhages. Evaluation of the athlete with an IPK involves determining the significance of the symptoms, length of duration, and association, if any, with specific athletic activity. A patient with minimal symptoms requires no treatment.

Figure 17-10 A wart is characterized by punctate hemorrhages that are obvious when the callus is trimmed.

Courtesy Roger A. Mann, MD, and Michael J. Coughlin, MD.

Radiographic evaluation entails weight-bearing films with markers to determine the exact location of the IPK (a long metatarsal may be associated with an IPK; likewise a marker may be located directly beneath the fibular condyle of a metatarsal head).

Pearl

Pressure Points

A Harris mat imprint is invaluable in identifying abnormal pressure points on the plantar surface of a patient’s foot. The patient is instructed to walk in a normal manner, stepping on the Harris mat. The test is repeated with the contralateral foot. Abnormal pressures are illustrated as unusually dark regions and will aid in making the correct diagnosis and appropriate treatment.

Conservative treatment

Conservative treatment revolves around paring the IPK and padding it to relieve the pressure (Fig. 17-11). A patient can be instructed to trim the lesion every 7 to 10 days, and this will significantly relieve discomfort. Placement of a metatarsal pad just proximal to the IPK can transfer pressure to the metatarsal diaphysis and relieve symptoms (see Case Study 2). Custom or prefabricated orthotic devices also can aid in relieving symptoms. Athletes may alter their workout, change sporting activities, or change duration or intensity of the workout, all with gratifying results.

Figure 17-11 Padding an intractable plantar keratosis often is successful treatment.

Case Study 2

A 50-year-old tennis player developed a painful callus beneath the second and third metatarsals. It was a diffusely thickened callus that began to limit his sports activities. On initial evaluation, the diffuse callus was trimmed and the patient instructed in how to care conservatively for the IPK. A pumice stone was used to pare the callus. The patient also obtained disposable scalpels to shave his thickened callosity. When he returned for further follow-up, radiographs demonstrated a long second and third metatarsal in relation to the adjacent metatarsals. A soft pad was placed in his shoe just proximal to the callosity. With the combination of shaving the callosity and padding it, symptoms were completely relieved and the patient returned to full sports activities. Later, a soft orthotic device was fabricated to relieve pressure beneath the second and third metatarsals. This convenient orthotic device can be moved from shoe to shoe and replaced the temporary soft pads that were used to alleviate his initial symptoms.

When all methods of conservative treatment have been exhausted, surgical intervention may be considered. Caution is advised in considering any metatarsal osteotomy in a high-level athlete. The possibility of delayed union, nonunion, or malunion can significantly impair later athletic activity. The development of a transfer lesion beneath another metatarsal head is not uncommon. Multiple metatarsal osteotomies are to be discouraged. Likewise, floating metatarsal osteotomies without internal fixation have a high rate of malunion with resultant transfer lesions.

Surgical Treatment: Partial Condylectomy ⁸

1 The foot is cleansed and draped in a routine fashion. As Esmarch bandage is used to exsanguinate the foot. It is padded carefully at the ankle and used as a tourniquet.

2 A longitudinal incision is centered over the metatarsal head with a “hockey stick” extension distal into the adjacent interspace. (The extensor tendon may be released temporarily to aid exposure and is repaired at the conclusion of the procedure.)

3 The MTP joint capsule is released and the toe is flexed to 90 degrees at the MTP joint.

4 An osteotome is used to osteotomize 25% of the plantar condyle. Care is taken to avoid fracture to the metatarsal head (Fig. 17-12). The condyle is removed.

5 A 0.045 K-wire introduced at the MTP joint is driven distally out the tip of the toe. With the MTP joint reduced, the pin is driven in a retrograde fashion, stabilizing the joint.

6 The extensor tendon (if released) is repaired. The skin is closed in a routine fashion.

7 A gauze and tape dressing is applied and changed on a weekly basis. The patient is allowed to ambulate in a wooden-soled shoe.

8 At 3 weeks, the sutures and K-wire are removed.

Figure 17-12 (A) Plantar condylectomy for a discrete intractable plantar keratosis. (B) Interoperative view of plantar condylectomy (one fourth to one third of the plantar metatarsal head is excised).

Athletic activity is permitted as swelling and pain decrease. The toe is protected for 6 weeks following surgery with taping immobilization. In general, a patient can return to nonimpact activities at 1 month. Limited-impact activities such as jogging are permitted at 6 weeks. Full-contact/impact activities can be resumed at 3 months.

Surgical Treatment: Metatarsal Osteotomy

1 The foot is cleansed and draped in a routine fashion. An Esmarch bandage is used to exsanguinate the foot. It is carefully padded at the ankle and used as a tourniquet.

2 A dorsal longitudinal incision is centered over the involved metatarsal.

3A If a distal oblique osteotomy⁹ is performed (Fig. 17-13), the cut is directed in a vertical direction. The metatarsal head is displaced upward 3 mm¹⁰ and fixed with a 0.045 K-wire.

3B If a vertical chevron osteotomy² is performed (Fig. 17-14), the V-shaped osteotomy is directed in a vertical direction. (This is more stable side to side than a transverse osteotomy.) The metatarsal head is displaced upward 3 mm and fixed with a 0.045 K-wire.

3C If a proximal transverse osteotomy¹¹ is performed (Fig. 17-15), a dorsal based wedge is excised. The farther proximal the osteotomy is located, the more elevation is achieved with wedge removal. (Care must be taken not to overcorrect at the osteotomy site.) The wedge may be removed with a sagittal saw or with a small rongeur. Internal fixation is recommended. A screw, pin, or wire loop fixation is used.

4 The wound is closed in a routine fashion. A gauze and tape dressing is applied and changed on a weekly basis. The patient is allowed to ambulate in a wooden-soled shoe bearing weight on his or her heel.

5 Sutures are removed 3 weeks following surgery. Percutaneous K-wires are removed 3 to 4 weeks following surgery. The forefoot then is strapped with tape and gauze until symptoms remit.

6 Radiographic confirmation of union is important before aggressive athletic activity can be commenced.