Fig. 10.1
Deformities of the toe
The etiology of a hammer toe deformity is often multifactorial and may be associated with hallux valgus, trauma, inflammatory arthritis, flexor digitorum longus (FDL) contracture, diabetes, and the use of shoes with narrow toe boxes. The peak incidence is reported in the fifth through seventh decades of life, and frequently the deformity develops insidiously. Often the deformity will cause pain, making shoewear difficult and placing the patient at risk of ulceration and subsequent infection.
Nonsurgical treatments include activity and shoewear modification, cushioned toe sleeves, and taping of the toes. With pronounced deformity, nonsurgical treatments are often unsuccessful. For correctable (flexible) deformities, multiple soft tissue procedures have been described. These procedures involve joint capsule releases and tendon lengthening as well as tendon transfers. For fixed deformities, surgical options include proximal interphalangeal joint (PIP) resection arthroplasty, PIP arthrodesis, and amputation.
Fusion for the treatment of hammer toe deformity was first described by Soule in 1910 [2]. Higgs in 1931 modified the procedure by fashioning the phalanx in a spike-and-hole construct [3]. These techniques were often supplemented by splinting postoperatively [4]. Taylor in 1940 first described the use of fixation in hammer toe fusion using a Kirchner wire (K-wire) [5]. Several modifications have subsequently been described, and numerous implant options and configurations have been proposed [6–11]. Nevertheless, the principles of arthrodesis, including joint preparation, bony apposition, adequate fixation, and proper positioning, remain unchanged [12].
In recent years, research has focused on newer intramedullary devices and alternative implant designs and orientations. Cannulated screws (Fig. 10.2), bioabsorbable pins, dual component intramedullary fixation devices, and shape memory metal have all been created and tested as alternatives to the classically described K-wire fixation method [6–8, 10, 13–18].
Fig. 10.2
Hammer toe corrections with intramedullary cannulated screws
Indications
Patients with hammer toes often report gradually increasing deformity of the lesser toe(s) in the absence of trauma. Patients may find shoewear modification or protective toe sleeves to be helpful as a first line of therapy. Increasing the size of the toe box and vamp often relieves pressure on the dorsal aspect of the PIP as well as the distal toe. In addition, taping of the toe, particularly with flexible deformities, may provide relief of symptoms.
Surgery may be indicated when patients are substantially limited by pain related to the hammer toe deformity that has persisted despite nonsurgical treatment.
Surgical options are tailored to the deformity characteristics. Hammer toes are subclassified into those that are flexible and those that are fixed. A flexible deformity can be corrected with manipulation of the toe or with ankle plantarflexion. Flexible deformities can typically be managed with soft tissue procedures, such as an FDL tendon transfer (Girdlestone-Taylor procedure).
Fixed deformities, in contrast, are not manually correctable and are not amenable to soft tissue procedures alone. Fixed hammer toe deformities are typically treated with PIP resection arthroplasty, PIP arthrodesis, or amputation. Many surgeons favor arthrodesis over arthroplasty given that this minimizes the risk of recurrent deformity. Amputation is generally reserved for elderly and low-demand individuals who seek a rapid recovery and is not optimal for many patients due to the resultant adjacent toe deformity that frequently occurs.
Contraindications
For a successful PIP arthrodesis , soft tissue and bone healing are required. Multiple patient factors can be detrimental to a successful outcome and must be evaluated and addressed preoperatively. As discussed in prior chapters, smoking and poor diabetic control place the patient at risk of complications. Smoking cessation and a glycated hemoglobin of less than 7.0% are advised before surgery [19, 20].
Absolute contraindications for hammer toe reconstructive surgery include active infection and inadequate vascular supply. Infection is a common problem with hammer toe deformities due to increased pressure at the dorsal PIP joint and the distal tip of the toe. If an infection exists preoperatively, reconstructive surgery should be delayed until the infection has cleared. Inflammatory markers such as WBC , ESR, and CRP should be followed to document infection clearance, in addition to clinical examination. If a preoperative deep infection is suspected, an MRI may be warranted to evaluate for osteomyelitis, in which case the patient may require an amputation. In patients suspected of having peripheral arterial disease, ankle-brachial indices (ABIs) and toe pressure measurements should be evaluated. Patients with compromised perfusion should be evaluated by a vascular surgeon before proceeding with elective surgery and counseled about the risk of wound complication.
Finally, patients should be counseled that the procedure is indicated for pain and skin compromise related to increased pressure in the toe box. Hammer toe correction is not recommended for cosmetic correction or the ability to wear fashionable shoes.
Pearls and Pitfalls
Preoperative Evaluation
Patients should be assessed for general health and medical comorbidities. Medical conditions that jeopardize the outcome of surgery must be known. Conditions we specifically inquire about include, but are not limited to, smoking, diabetes, peripheral neuropathy, vascular disease, history of trauma, and family history of toe deformity. A careful neurovascular examination should be performed. Signs of peripheral arterial disease such as skin changes, loss of hair, muscular atrophy, or unequal or absent peripheral pulses should be further evaluated by vascular testing and referral to vascular surgery if indicated. Sensation testing with Semmes-Weinstein monofilament should also be considered as patients with peripheral neuropathy are at higher risk of complication from hammer toe deformity and corrective surgery due to the loss of protective sensation. A cavovarus foot, muscular atrophy, sensory deficits, and a positive family history all may be signs of an underlying neurologic cause, such as Charcot-Marie-Tooth, and further testing or referral may be indicated.
Careful examination of the toes should be performed. The rigidity of the deformity should be assessed. In addition, the MTP joint should be evaluated as hyperextension of the joint and even dorsal subluxation or dislocation may be present. Hallux valgus is also commonly associated with hammer toe and may need to be addressed at surgery. Weight-bearing AP and lateral radiographs of the foot should be obtained. Metatarsal length and the cascade of the metatarsal heads should be noted.
Position of Arthrodesis
After the joint is prepared, positioning is approached from a standpoint of form and function. Careful visualization is used to position the toe in a natural position such that it does not place pressure on the adjacent toes and appears rotationally neutral. A flat surface such as a basin or surgical tray may be used to simulate weight-bearing of the foot intraoperatively. The goal is for the toe to gently rest on the flat surface without undue pressure and for there to be no rotational or sagittal deformity. The toe should be able to be gently lifted off the flat plate.
Fixation
Numerous options are available for fixation . K-wires, allograft pins, shape memory metal, headless intramedullary compression screws, and dual-component intramedullary devices have all been described. While all are viable options, our preference is to use a single 0.062-inch K-wire. At times, smaller patients require a smaller K-wire. Risk factors for K-wire breakage include longer pin duration, smaller (e.g., 0.045 inch) size, metatarsal head resection, and crossing the MTP joint [21]. K-wire fixation is our preference due to its low cost, proven effectiveness, and the ability to leave no retained hardware .
Long Metatarsal
Especially when treating a second hammer toe, the metatarsal length and MTP joint should be evaluated. If the second metatarsal head projects past the normal cascade of the MTP joints and the patient has symptoms consistent with metatarsal overload or MTP instability, then the long second metatarsal may need to be addressed. Various metatarsal shortening osteotomies have been described. Our preference is to perform a Weil osteotomy. This can be performed by making an additional longitudinal incision overlying the metatarsal head or simply by extending the dorsal longitudinal incision proximally along the ray.
Vascular Compromise
After fixation of the toe and before the sterile field is broken, the tourniquet should be let down, and the vascular status of the toe should be carefully examined. After correction of a chronic toe deformity, vascular compromise is not uncommon. If the toe appears white, the following steps are recommended. At first, wait up to 10 min to allow for recovery of any temporary vasospasm. During this time, apply a warm saline-soaked gauze to the toe, and ensure no constrictive dressings are in place. Nitropaste may also be applied. If the toe remains compromised, place a 5–10° flexion bend in the K-wire and reassess. Finally, if this does not improve capillary refill and the color of the toe, then remove the K-wire. In this situation, we recommend “buddy stitching” the toe to an adjacent toe with nylon suture to provide additional stability.
Approaches and Techniques
PIP Fusion
A dorsal approach to the PIP joint is commonly used as it provides excellent visualization of the joint and avoids neurovascular structures in the toe. The patient should be positioned supine so that the foot is on the most distal aspect of the table to allow for easy radiographic evaluation. A small roll can be placed under the hip to bring the patient’s lower extremity into neutral. A well-padded tourniquet should be applied. Depending on patient anatomy, a calf or thigh tourniquet should be considered as an ankle tourniquet with drapes may interfere with drill positioning during the case.
A dorsilinear incision is made from the MTP to the DIP joint. This incision is our approach of choice due to the ability to extend proximally if the MTP joint must be addressed (Fig. 10.3). Alternatively, a transverse elliptical incision at the level of the PIP joint may be advantageous if a large callus must be resected (Fig. 10.4).
