Hallux hammertoe deformity is frequently associated with tip-of-toe ulcers, dorsal IPJ ulcers, and plantar MPJ ulcers. It is reasonable to pursue elective hammertoe surgery in an attempt to address the underlying structural deformity before osteomyelitis develops, which puts the toe at risk for amputation. The open wound would ideally be healed prior to elective surgery, but this is not always practical as deformity correction may be necessary to resolve the wound. Hallux hammertoe repair typically consists of flexor hallucis longus (FHL) tenotomy, IPJ fusion, or IPJ arthroplasty. Extensor hallucis longus (EHL) lengthening or transfer to the first metatarsal head is added if the EHL is a contributing deforming force. Ideal procedure selection depends on the flexibility of IPJ and MPJ deformity, location and depth of the ulcer, and suspicion for osteomyelitis. Elective surgery frequently allows procurement of bone for biopsy and primary or flap closure of the wound. The simplest approach is an office-based FHL tenotomy which is indicated for reducible IPJ contracture without bone or soft tissue infection, as shown in case 1 (Figs. 15.4, 15.5, 15.6, and 15.7). This ambulatory procedure is highly amenable to the office setting in patients with neuropathy, and there is no need to hold anticoagulation therapy as bleeding is minimal. Immediate weight bearing is preferred to promote stretch after tendon and joint release. Deep and complicated tip-of-toe ulceration is often best treated with hallux distal Symes amputation as described later.

Rigid deformity of the IPJ is generally treated with joint fusion or arthroplasty (Fig. 15.8). Interphalangeal joint fusion requires internal fixation or pin fixation which is less practical in patients with open wounds or suspected osteomyelitis. If uncomplicated wounds can be healed preoperatively and the risk of osteomyelitis is low, elective hallux fusion is preferred. This approach leads to a more stable and functional toe. A staged approach is also possible with initial FHL tenotomy followed by delayed fusion once the distal ulcer heals.

A primary indication for hallux IPJ arthroplasty is a nonhealing IPJ plantar ulceration with suspected or imminent osteomyelitis within the head of the proximal phalanx, as demonstrated in case 2 (Figs. 15.9, 15.10, 15.11, 15.12, 15.13, 15.14, 15.15, 15.16, 15.17, 15.18, and 15.19). We commonly incorporate a unilobed flap with or without a secondary dorsal incision for bone resection [8]. A dorsal incision is helpful when patients present with cellulitis and inflammation on the dorsum of the hallux despite the wound being plantar as these clinical signs likely indicate violation of the joint capsule. Since infection most commonly spreads from an area of higher pressure (plantar foot) to an area of lower pressure (dorsal foot), the spread of infection to the dorsum of the foot is common once the joint capsule is compromised [9]. A course of conservative wound treatment is warranted but often ineffective for IPJ ulcer treatment due to abnormal biomechanical forces. Surgical intervention would ideally be implemented before cellulitis or osteomyelitis develops, but a staged approach is common with acute infection.

The benefits of this digital salvage procedure include complete ulcer excision, early bone resection and biopsy, flap coverage with viable soft tissue, and offloading of mechanical pressure at the plantar hallux IPJ. Care is taken to select patients with adequate MPJ dorsiflexion and healthy surrounding soft tissue which is more likely with early intervention before the onset of extensive soft tissue or bone infection. Clinical exam of patients with ulcers at the plantar IPJ location commonly identifies hyperextension of the IPJ associated with functional hallux limitus. Plantar IPJ bone prominence is also common along with ankle equinus deformity. A weight bearing stress dorsiflexion lateral hallux view is helpful to assess for functional MPJ range of motion [10]. Standard weight bearing X-rays are also useful to evaluate for osteomyelitis, a prominent plantar IPJ sesamoid, or other causes of excessive plantar pressure at the IPJ. MRI may also help determine the extent of osteomyelitis to assess whether the toe is amenable to IPJ arthroplasty. If osteomyelitis extends throughout the entire proximal phalanx or both the proximal and distal phalanges, hallux amputation may be a better option. Excessive bone debridement for necrosis or digital deformity causes instability of the tip of the toe and thus does not preserve digital function or cosmetic appearance. A Schrudde Type 1 unilobed rotational flap design is used with the size of the flap being approximately 75 % of the total soft tissue defect after wound excision (Fig. 15.11c) [11]. This is typically a single-stage outpatient procedure that is performed supine without the use of a tourniquet. Staged surgery is possible with initial excision of the wound followed by debridement and biopsy of the proximal phalanx. Final bone resection and delayed flap closure of the wound is performed once cellulitis and abscess resolve. Persistent infection despite initial bone resection could always be converted to hallux amputation, especially if the soft tissues remain compromised by infection or poor circulation. Staged surgery also allows time for vascular intervention if indicated.

Plantar first MPJ ulcers are difficult to heal due to significant stress applied during gait. This stress is amplified in patients with diabetic peripheral neuropathy combined with certain biomechanical alterations that contribute to plantar MPJ ulcer formation. A recent study found that diabetics with peripheral neuropathy and foot ulcer formation demonstrated a significantly lower range of motion at the hips, knees, ankles, and first MPJ compared to diabetics without ulcer formation [12]. Previous studies have shown abnormally high pressure under the metatarsal heads in diabetic patients with peripheral neuropathy. Patry also reported that forefoot pressure was 2.3 times higher than rearfoot pressure in those patients [13]. These findings help explain why ulcers at this location are common and difficult to heal with propensity to progress to the point of osteomyelitis.

Chronic wounds under the first MPJ frequently develop osteomyelitis of the sesamoid bones prior to extension of infection into the MPJ and the adjacent metatarsal and proximal phalanx (Fig. 15.20). Early surgical intervention with sesamoidectomy for nonhealing or recurrent wounds can be effective to avoid partial first ray amputation which is often necessary once the joint becomes exposed. The procedure is most effective when performed early before the onset of soft tissue infection. Our typical approach is to employ standard wound healing measures until the point when the wound probes to bone, which is the primary indication for surgery. It is important to evaluate patients with chronic or recurrent plantar first MPJ ulcers for related deformities including ankle equinus, plantar displacement of the first metatarsal, or hallux hammertoe contracture. These deformities can be addressed surgically prior to onset of infection.