Problem: A claw toe is a lesser toe having dorsiflexion of the proximal phalanx on the lesser metatarsophalangeal (MTP) joint and concurrent flexion of the proximal interphalangeal (PIP) and distal interphalangeal (DIP) joint.

Claw toe can be differentiated from hammertoe based on the combined dorsiflexion of the MTP joint and plantar flexion of the DIP joint in claw toe, whereas a hammertoe may have some hyperextension (HE) at the MTP joint or some flexion at the DIP joint, but not both concurrently. Typically, the DIP joint is extended in a hammertoe .

Hammertoe is differentiated from curly toe, which has combined plantar flexion of all 3 joints, and from a mallet toe, which has a neutral position of the MTP and PIP joints and flexion at the DIP joint. See Table 1 for descriptions of lesser toe deformities. Clawing often affects multiple toes .

Table 1. Lesser Toe Deformities

*Cannot coexist

Frequency: The incidence of claw and hammertoe deformities ranges from 2-20%, with gradually increasing frequency as people age. Therefore, it is most often seen in patients in the seventh and eight decades of life. Women are affected 4-5 times more often than men. Little is mentioned in the literature regarding these deformities in non–shoe-wearing populations. The majority of people with this condition have no underlying disease responsible for the claw toe deformity. However, it is seen with neuromuscular diseases, such as multiple sclerosis, Friedreich ataxia, Charcot-Marie-Tooth disease, cerebral palsy, mild dysplasia, stroke, and lumbar nerve root impingements. Metabolic diseases, such as diabetes and inflammatory arthropathies (eg, rheumatoid arthritis, psoriasis), also can be accompanied by claw toe deformity.

Etiology: Claw toe deformity results from altered anatomy and/or neurologic deficit, resulting in imbalance between the intrinsic and extrinsic musculature to the toes.

Pathophysiology: The extensor tendon, which crosses the MTP joint, is held over the MTP joint by an aponeurotic band of fibrous tissue. Although it does not insert into the proximal phalanx, it is able to dorsiflex the proximal phalanx of the MTP joint through this aponeurotic band, which goes around the MTP joint to insert onto the plantar plate. The extensor tendon splits into 3 parts over the proximal phalanx. The central slip attaches itself to the dorsal aspect of the base of the middle phalanx. The medial and lateral slips rejoin distally to insert on the dorsal aspect of the base of the distal phalanx . The extensor tendon is only capable of extending the PIP and DIP joints when the MTP joint is in neutral flexion; otherwise, this is accomplished by the intrinsic musculature.

The intrinsics are made of the lumbricals, which are strong extenders of the PIP and DIP joints by virtue of their attachment onto the extensor sling and the interossei. Interossei are weak extensors of the interphalangeal (IP) joints because so few fibers reach the extensor sling. Furthermore, when the MTP joint is hyperextended, the lumbrical power in extending the PIP and DIP joints is reduced due to a mechanical disadvantage. The flexor digitorum longus (FDL) tendon inserts into the plantar aspect of the distal phalanx, and the flexor digitorum brevis inserts onto the middle phalanx. Thus, there is no major antagonist to dorsiflexion of the proximal phalanx. Hence, when the proximal phalanx dorsiflexes, there is static tightening of the flexors, which subsequently flexes the PIP and DIP joints. Stabilization of the lesser MTP joint comes from the static restraint of the plantar plate and the collateral ligaments.

The collateral ligaments have been reported as the primary stabilizers of the lesser MTP joint. There are two sets of collateral ligaments. Both emanate from the lateral metatarsal head. The phalangeal collateral ligament (PCL) inserts into the proximal phalanx, and the accessory collateral ligament (ACL) inserts onto the plantar plate. The plantar plate is attached from the base of the proximal phalanx to an origin on the metatarsal head, just proximal to the plantar articular cartilage.

When the collateral ligaments and plantar plate lose resiliency or are stretched through repetitive dorsal directing forces on the proximal phalanx from ground reactive forces, the proximal phalanx dorsiflexes. Without a strong plantar flexor attached to the proximal phalanx, the proximal phalanx remains in dorsiflexion, and the PIP and DIP joints subsequently flex. When the flexed position of the PIP and DIP joints remains constant, the collateral ligaments fibrose along the sides of the PIP and DIP joints, and the position of their joints becomes fixed. When this occurs, the claw toe deformity becomes rigid, whereas previously it was considered flexible. This separation of flexible and rigid most often occurs at the PIP joint.

Clinical:
 

Patients with claw toe deformities can present with a variety of complaints related to the position of the toe. Patients most often complain of pain at the dorsal PIP joint from an impingement of the toe on the shoe. A callus or erythema is present over the dorsal PIP joint where it abuts the shoe. Patients also may complain of pain at the tip of the toe from pressure against the point of the distal phalanx. Patients can have a callus at the tip of the toe and a malformed nail, especially patients with diabetes and neuropathies . When pain beneath the callus exceeds the neuropathic threshold in a patient with diabetes, an abscess may be present beneath the callus, which is discovered only when the callus is debrided. The other source of pain is the MTP joint, which develops synovitis because of irritation from its extended position and instability.

Another less often seen presentation is impingement of the lateral claw toe upon the adjacent toe, causing a callus or soft corn on the medial border of the claw toe. This usually is secondary to clawing of the fourth or fifth toe. Finally, the relative increased pressure beneath the metatarsal head from the inability of the toe to share in weightbearing can result in metatarsalgia. This occurs secondary to distal migration of the plantar fat pad with hyperextension of the MTP joint.

Physical examination

Assessing claw toe primarily consists of a physical examination with additional tests as required. With the patient sitting, each of the 3 joints (ie, MTP, PIP, DIP) is tested for flexibility in the sagittal plane and stability in the frontal and sagittal plane. Vascularity of the toe is assessed clinically, and the presence of calluses or erythema is duly noted. Normal sensation can be determined by the patient’s ability to feel a 0.5-gram force with a monofilament pressure device. Failure of the patient to detect a 10.0-gram force monofilament applied to the foot indicates loss of protective sensation.

Contraindications: Contraindications to operative treatment include poor vascularity to the toe (including vascular problems that could lead to ischemia and possible need for amputation following surgery, eg, diabetes, atherosclerosis) and poor skin quality. Of course, an open infected wound, for instance on the PIP joint from shoe pressure, should also be resolved prior to surgery.

After medical treatment is initiated, consider conservative therapy, including avoidance of wearing high-heeled, narrow-toed shoes, which increase dorsal ground reactive forces on the toe and crowd the toes against each other, producing impingement. A shoe with a wide toe box, soft upper shoe, and stiff sole to absorb dorsally directed forces against the plantar plate is appropriate. Some high quality tennis shoes fulfill these criteria. 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 PIP joint and tip of the toe . A longitudinal pad beneath the toe can prevent point pressure at the tip of the toes.

Surgical therapy: 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.

At the PIP joint (if it is completely flexible), an FDL transfer to extensor tendon can bring the toe into alignment. This is accomplished by making a longitudinal cut across the plantar MTP proximal skin crease, retracting the skin with one or two small Meyerding retractors if necessary, splitting the tendon sheath, isolating the FDL tendon between the FDL brevis tendons, passing a small curved hemostat beneath the long flexor to establish tension in the tendon, and then cutting the tendon distally through a small stab incision in the skin just proximal to its attachment.

The two distal raphes are held with two hemostats, and blunt separation is accomplished by cutting the distal connecting raphe of the FDL tendon into two parts with tenotomy scissors. Through the dorsal incision used to address the Z tendon lengthening, curved hemostats are directed circumferentially around the proximal phalanx. The tip of the FDL tendon raphe is grasped on the medial side and brought from the plantar wound dorsally. A similar technique is used to grab the lateral raphe and bring it dorsally. The tendons are attached to themselves and the repaired extensor Z-lengthened tendon with 2-0 absorbable suture. Absorbable suture prevents the formation of a permanent knot bump on the dorsal aspect of the toe.

If the PIP is fixed in flexion or cannot be brought back easily to a neutral position, removal of the distal portion of the proximal phalanx along with the articular cartilage of the middle phalanx is accomplished. If only a PIP resection is required (an FDL transfer is not needed), a shorter longitudinal incision can be made dorsally over the MTP joint and proximal phalanx for the Z lengthening, dorsal capsulotomy, and collateral ligament release surgery. A transverse incision can then be made at the PIP joint for correction of the fixed deformity.

If an FDL transfer is necessary along with a PIP resection, it may be accomplished with extension of the dorsal longitudinal MTP incision over the PIP joint. Once through the skin, a continuation of the Z lengthening of the tendon may be accomplished across the PIP joint. The distal portion of the proximal phalanx is isolated by cutting the collateral ligaments and exposing the bone. The distal portion of the proximal phalanx is cut with a small sharp bone-cutting device (eg, saw), just proximal to the flare of the condyles.

The articular cartilage then is removed from the proximal portion of the middle phalanx. A 0.54-mm doubly pointed Kirschner wire (K-wire) is driven into the distal cut bony surface of the middle phalanx, taking care to keep the guidewire in the center of the bone to avoid eccentric positioning. The K-wire is brought out of the tip of the toe while the DIP joint is held in neutral. The K-wire then is grasped distally and drilled back through the proximal phalanx across the metatarsal head, holding the IP joints in neutral with slight flexion at the MTP joints.

The resected PIP joint is now inspected to avoid eccentricity and bone prominence. If this is found, the prominence is resected or the guidewire is replaced. This guidewire (being somewhat larger than the previously recommended 0.45-mm K-wires) is less likely to break, does not become unstable (which would cause infection), and can be left in place for 4 weeks to increase the chance of fusion and/or fibrosis of the PIP joint.

If the PIP joint is not resected, the author believes that stabilization of soft tissue at the MTP joint is important to promote ultimate healing in the corrected position. Therefore, a K-wire can be driven from the articular cartilage of the proximal phalanx out of the tip of the toe and back antegrade through the metatarsal head. This also can be attempted retrograde from the tip of the toe, with the toe in a slightly plantar flexed position at the MTP joint and neutral at the PIP and DIP joints. This is more difficult. However, even if the pin only engages the capsular tissue of the MTP joint, this is often enough to keep the joint relatively stable. The pin is removed after 2 weeks, as the goal is joint stability, not arthrodesis. The joint may be taped for an additional 4 weeks if further immobilization is necessary.

Almost always, the DIP joint is flexible in a claw toe and is relieved with a flexor-to-extensor transfer. However, should a fixed DIP joint be found, especially if it is part of the problem (ie, pressure on the nail or the tip of the toe), resection of the distal portion of the proximal phalanx and articular portion of the distal phalanx can be performed in a similar fashion to that of the PIP. A similar pinning technique to that described above also may be used.

Sometimes, such chronic dorsal dislocation of the proximal phalanx is present on the metatarsal head that reduction of the proximal phalanx is not possible, or if attempted, leaves an extreme tightness across the MTP joint, resulting in vascular embarrassment. In this instance, an osteotomy, from the proximal dorsal articular surface of the metatarsal head in a direction plantar proximal along a plane parallel to the sole of the foot, allows metatarsal head retraction and reduction of the tension in the neurovascular bundle. The dorsal lip of the metatarsal shaft can be removed, and the head is fixed to the remaining shaft with a screw or continuation of the lesser toe pin into the dorsal metatarsal head and then into the center portion of the shaft. This technique is preferable to metatarsal head resection, which can result in a transfer lesion to another metatarsal head.

Forefoot surgery typically is performed on an outpatient basis. A fresh dressing is applied the next day, and stitches are removed after 2 weeks. Arthrodesis pins are removed after 4 weeks, and the other types of pins are removed after 2 weeks. Patients may shower with pins protruding from the toes.

Complications: