Mallet Toe


Background

A mallet toe is a fixed or flexible deformity of the distal interphalangeal (DIP) joint of the toe. It is characterized by neutral positioning of the metatarsophalangeal (MTP) and proximal interphalangeal (PIP) joints in the face of a flexed DIP joint, in contrast to the extended or neutral position of the MTP joint and flexed position of the PIP joint characterized by the more common hammertoe deformity. In certain patients with hammertoe deformity, the DIP can present in flexion. Given this overlap in presentation at the DIP joint, clinicians should be familiar with both conditions and be able to distinguish between them. [1]

Both pain and callosity may be the presenting complaints when the DIP joint of the toe has abnormal flexion, regardless of whether it is fixed or flexible.

Treatment of mallet toe deformity is relatively straightforward (see Treatment). Some controversy exists over the need for flexor tenotomy when DIP joint arthrodesis is attempted and the question of whether this leads to a higher incidence of hyperextension deformity and PIP joint flexion at the adjacent PIP joint.

For information on related topics, see Claw Toe and Hammertoe Deformity.

Anatomy

The DIP joint is a hinge joint with collateral and accessory collateral ligaments and a plantar plate. The flexor sheath extends to the DIP joint. [23]

Pathophysiology

The principal pathophysiology is flexion of the DIP joint with pressure on the tip of the toe, often with associated attenuation of the extensor tendon (see the image below). This may lead to callosity or nail deformity on the tip of the toe. The deformity may be flexible in cases where the principal problem is an overtight flexor digitorum longus. However, the deformity is typically fixed in cases where the plantar joint structures are contracted or alteration of the joint surfaces restricting joint range of motion has occurred. [4567]

Classic mallet toe. Note flexion when toe is dorsiClassic mallet toe. Note flexion when toe is dorsiflexed.

Etiology

Mallet toe deformity of a long toe is usually idiopathic. Inappropriate shoe wear, iatrogenic causes (eg, previous PIP joint fusion), congenital abnormalities, trauma, neuromuscular disorders, and pes cavus can all lead to the deformity. [8]

Epidemiology

In the United States, mallet toe deformity is much less common than hammertoe deformity, with a 1:9 ratio. It occurs most often in the second toe (75%) but can also occur in the remaining lesser toes. In as many as 12% of cases, associated lateral or medial deviation may be present.

The international incidence of mallet toe is unknown; however, population‐based studies in Australia and Sweden reported that surgical management of these deformities accounts for between 28% and 46% of all forefoot surgery performed in those countries. [910]

Prognosis

Most series found excellent results in 85-97% of cases. [11In some series, tenotomy seemed to increase satisfaction rates. Bony union of the DIP joint had higher satisfaction rates than fibrous union did when resection was carried out.


History

The patient with a mallet toe usually presents with pain, either from callosity or from pressure on the nail. Occasionally, a cosmetic deformity is noticed, often by anxious parents or family, without symptoms. The physician should obtain a thorough history, noting any family history or history of trauma, previous surgery, or associated infections. The severity of the presenting symptoms should be evaluated, as well as the presence of generalized conditions, such as diabetes, vascular disease, neuropathy, or arthropathic disease.

Physical Examination

The examination should address overall foot alignment, the presence of palpable pedal pulses, signs of other foot deformities, and any prior surgery. Specifically with respect to the toe, it is important to assess the metatarsophalangeal (MTP) joint, the proximal interphalangeal (PIP) joint, and the locations of callosity and nail deformity. The flexibility of the distal interphalangeal (DIP) joint should be evaluated with the toe plantarflexed and dorsiflexed at the MTP joint and the PIP joint.

Differential Diagnoses


Laboratory Studies

Obtain routine preoperative hematology. In addition, undertake investigation for any intercurrent medical problems (eg, diabetes) before surgery. Patients taking methotrexate or similar medications may need hematologic monitoring before surgery. General preoperative studies (eg, urinalysis) may be needed, depending on the patient's medical condition.

Imaging Studies

Obtain weightbearing radiographs to assess the whole foot. Occasionally, specific films of the distal interphalangeal (DIP) joint may be obtained. Dental plates can be useful for these small images.

If underlying neurologic pathology is suspected, studies appropriate for this workup may be needed (eg, computed tomography [CT] of the spine or magnetic resonance imaging [MRI]). Infection may be an indication for technetium or gallium bone scans. [12]

Preoperative chest films may be needed, depending on the patient's medical condition and age.

Other Tests

Preoperative electrocardiography (ECG) may be warranted, depending on the patient's general medical condition or age, especially for diabetic patients.



Approach Considerations

The usual indication for surgery is the presence of a painful deformity for which reasonable attempts at nonoperative treatment, including shoe-wear modification, have failed. [13Occasionally, cosmesis may be raised as a presenting complaint.

Contraindications for surgery include the following:

  • Vascular compromise
  • Active infection
  • Lack of symptoms
  • Significant psychiatric disorders

The literature does not support the position that patients with lesser-toe deformities who have rheumatoid arthritis need be treated differently from patients with similar deformities who do not have rheumatoid arthritis; however, little has been published on outcomes in this patient population. [1415Noncompliance or inability to comply with nonoperative treatment should be considered a relative contraindication.

Medical Therapy

Nonoperative treatment focuses on relieving the pressure under the tip of the toe. This can be accomplished with extra-depth toe-box footwear. Soft orthoses or toe protectors are useful.

Surgical Therapy

Surgery can be performed under local or regional block, and in appropriate patients, it can be performed on an outpatient or day-surgery basis.

Surgical therapy includes the following options [16:

  • Flexor tenotomy, possibly including plantar capsular release and pinning
  • Condylectomy and fusion of the middle to distal phalanx
  • Partial or complete amputation of the distal phalanx (rarely indicated)

A flexible mallet toe is best treated with a flexor tenotomy. A fixed deformity requires skeletal work, whether via condylectomy, resection arthroplasty, or arthrodesis at the distal interphalangeal (DIP) joint. An ulcerated or infected toe would do best with a terminal amputation. [11]

Tenotomy is performed by making a small lateral or medial incision over the distal end of the middle phalanx. The author prefers to visualize the tendon sheath directly by retracting the skin with double skin hooks or a Ragnell. The sheath is incised longitudinally, and the tendon is hooked with a small arthroscopic probe. The tendon then can be divided under direct vision.

If some residual contracture is present, the plantar capsule can be stripped of the phalanx with a Freer dissector. A 1.1 Kirschner wire (K-wire) can be used to immobilize the joint in the neutral position. [17One skin stitch or Steri-Strip is used to close.

DIP joint arthrodesis is carried out by excising a small ellipse over the dorsal aspect of the joint, including the extensor. The bone ends are excised, and pinning is carried out. The skin and extensor are closed in one layer. [18]

Some controversy exists regarding the need for flexor tenotomy when DIP joint arthrodesis is attempted and the question of whether this leads to a higher incidence of hyperextension deformity and proximal interphalangeal (PIP) joint flexion at the adjacent PIP joint.

Amputation is rarely necessary; when indicated, it is usually performed as a terminal Syme procedure. [1920The nail bed and the terminal half of the phalanx are excised.

Postoperative Care

Postoperatively, routine dressings are applied. The patient can mobilize weightbearing in a postoperative shoe. Elevating the limb for the first 5-7 days reduces postoperative swelling. Sutures are removed at 10-14 days. Pins are usually removed at 4 weeks.

Complications

Recurrence is possible, especially if the deformity is more than an isolated mallet toe. Failure to divide the flexor completely can also cause recurrence. Flail toe is occasionally a problem with shoe or stocking wear if excessive resection has occurred, but it is seldom painful.

Neurovascular problems (eg, numbness, neuromata, and dysvascularity) can also occur. Prolonged swelling is often noted, and patients should be warned beforehand that this may occur. Residual nail deformity is also common. Hyperextension deformity of the DIP joint and flexion deformity of the PIP joint can also occur.