Hammertoe Repair




Hammertoe Repair
Background
Hammertoes, claw toes and mallet toes are a very common lesser toe (toes 2 through 5) deformity that often is painful, and limits function and shoe wear selection. A hammertoe is a deformity in which the proximal inter-phalangeal joint (IPJ) is flexed. A claw toe is a deformity of the toe in which the meta-tarso-phalangeal (MTP) joint is pulled up or extended. The proximal and distal joints (IPJs) are flexed, producing a toe that resembles a claw. A mallet toe is a lesser toe deformity in where the distal IPJ is flexed. Claw toes may be flexible (easily straightened) or rigid, with stiff joints or tight tendons preventing correction. A claw toe deformity can cause increased pressure or friction on the tip of the toe and over the top of the proximal and distal IP joints, due to rubbing against the shoe toe box. When the toe cocks up, the metatarsal bone is pushed downward, resulting in increased pressure under the ball of the foot (metatarsalgia). This increased pressure can result in a thick, painful callus underneath the ball (MTP joint) of that toe. In severe cases of claw toe deformity, shoe wear selection obviously can be severely limited.

Although claw toes, hammertoes, and mallet toes are technically different, they behave and look similarly, and will be discussed as one problem. They may be caused by trauma (stubbing the toe and producing a fracture or tear of the tendons that straighten or extend the toe). More commonly, the deformity occurs slowly or chronically. Neuromuscular diseases such as cerebral palsy, polio, Charcot Marie Tooth disease, stroke, closed-head injury; or nerve injury or other rare, neuromuscular problems can cause imbalance between the extensor tendons that straighten the toe and the flexor tendons that bend the toes. This tendon imbalance can result in a progressive claw toe deformity. Inflammatory conditions such as rheumatoid arthritis, gout, systemic lupus, exanthematous disease, and Reiter's disease may cause synovitis of the joints, and result in stretching or laxity of joint ligaments which allows the deformity to develop. People with a high-arch (cavus) type foot may be prone to develop claw toes.

People with hammertoe may have corns or calluses on the top of the proximal joint of the toe or on the tip of the toe. They may also feel pain in their toes or feet and have difficulty finding comfortable shoes. Treatment is initially directed at relieving the pressure points. Unless arthritis develops, the condition is not painful. Pain occurs when pressure focuses on certain areas of the toe. Relieving the pressure will not cure the problem but will lessen the symptoms. Various pads and strappings are commercially available to reduce the deformity and relieve pressure over painful corns. If the deformity is not of long duration and an extension deformity at the MTP joint is not also present, daily manipulations and taping the toe so that the MTP is not extended occasionally can correct the flexion deformity at the proximal interphalangeal joint. A shoe with a wide, high toe box, soft upper shoe, and stiff sole to absorb dorsally directed forces against the plantar plate is appropriate. A metatarsal bar can be added to the shoe to avoid metatarsal pressure, but patients more easily accept metatarsal pads. Cushioning sleeves or stocking caps with silicon linings can relieve pressure points at the proximal IP joint and tip of the toe. A longitudinal pad beneath the toe can prevent point pressure at the tip of the toes.

Initially, hammertoes are flexible and can be corrected with simple measures but, if left untreated, they can become fixed and require surgery. The actual procedure will depend on the type and extent of the deformity. In the otherwise healthy patient with a digital deformity, selection of an appropriate procedure(s) is based upon the joint(s) involved, the associated flexibility of the contracture(s), and the related abnormalities that exist. Because the MTP joint is always dorsiflexed by definition, some correction of its position is necessary to restore a more neutral angle at the MTP joint. This consists of Z lengthening of the extensor tendon, dorsal MTP capsulotomy, and collateral ligament release. If deviation is present in the frontal or coronal plane in addition to claw toe, the loose collateral ligament side can be imbricated instead of released.

Many different procedures have been described in the literature for the correction of hammertoe deformity. Regardless of the technique used, there are goals that need to be achieved through surgery:
Delay rapidity of progression and severityDiminish discomfortPrevent complications such as atrophic ulcerations over osseous prominences in the individual with sensory deficitProvide greater stabilityRestore and/or maintain ambulatory ability.
Pietrzak et al (2006) stated that the surgical correction of hammer toe deformity of the lesser toes is one of the most commonly performed forefoot procedures. In general, percutaneous Kirschner wires are used to provide fixation to the resected proximal inter-phalangeal joint. Although these wires are effective, issues such as pin tract infections as well as difficult post-operative management by patients make alternative fixation methods desirable. This study biomechanically compared a threaded/barbed bioabsorbable fixation implant made of a copolymer of 82 % poly-L-lactic acid and 18 % polyglycolic acid with a 1.57-mm Kirschner wire using the devices to fix 2 synthetic bone blocks together. Constructs were evaluated by applying a cantilever load, which simulated a plantar force on the middle phalanx. In all cases, the failure mode was bending of the implant, with no devices fracturing. The stiffness (approximately 6 to 9 N/mm) and peak load (approximately 8 to 9 N) of the constructs using the 2 systems were equivalent. Accelerated aging at elevated temperature (47 degrees C) in a buffer solution showed that there was no reduction in mechanical properties of the bioabsorbable system after the equivalent of nearly 6 weeks in a simulated in-vivo (37 degrees C) environment. These results suggested that the bioabsorbable implant would be a suitable fixation device for the hammer toe procedure. These findings need to be validated by additional research.

Witt and Hyer (2012) noted that hammertoes are common deformities that are often surgically treated using arthrodesis or arthroplasty of the proximal inter-phalangeal joint with percutaneous, temporary Kirschner wire fixation. However, percutaneous Kirschner wire fixation is associated with potential complications, including wire migration, breakage, and pin tract infection. Furthermore, the complications of pseudoarthrosis and nonunion are seen using this technique owing to a lack of rotational control of the Kirschner wire. Another drawback of this implant is the need for wire removal and the associated patient anxiety with this in-office procedure. In a case-series study (3 patients and a total of 7 toes), these researchers described an alternative method of hammertoe fixation using a permanently implanted, 1-piece intramedullary device used to stabilize the proximal inter-phalangeal interface. The potential advantages of this prosthesis include elimination of wire migration and breakage, enhanced control and stability of the digit, elimination of potential pin tract infection, and decreased patient anxiety since hardware removal is not required. The patients were followed-up for approximately 1 year after the surgery, and no intra-operative or post-operative complications were observed. The implant maintained proper clinical and radiographic alignment throughout the observation period, without implant failure or breakage. All patients were satisfied with the cosmetic appearance of their surgically corrected toes and were able to perform all activities of daily living without the use of assistive devices. Also, their post-operative pain and function were acceptable. The authors concluded that the implant used in the patients described in the present report appears to be a viable alternative for the treatment of hammertoe. These preliminary findings need to be validated by well-designed studies.



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