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Basics ⬇

Author(s): AntonioHoward, MBBS, MSc, FAAPMR, CAQSM and Robert D.Martin, MD

Description

  • Toe joint deformities result from an imbalance between flexor and extensor forces about the interphalangeal (IP) and metatarsophalangeal (MTP) joints. Pain often results from abnormal distribution of pressure and increased friction against other toes or footwear:
    • Mallet toe is a flexion deformity at the distal interphalangeal (DIP) joint.
    • Hammer toe is a flexion deformity affecting the proximal interphalangeal (PIP) joint. Concomitant extension at the MTP joint may be present.
    • Claw toe is a flexion deformity affecting the PIP and DIP joints. Concomitant extension at the MTP joint is always present.
  • Acute deformities are usually flexible/reducible. Chronic deformities may become rigid/fixed.

Epidemiology

  • Incidence increases with age.
  • Female preponderance, especially after age 70 yr
  • Claw toe deformity may be present in up to 46% of patients within the first year after a severe stroke.
  • Hammer toe deformity is the most common lesser toe deformity. The second toe is most commonly affected.

Etiology and Pathophysiology

Imbalance between flexor and extensor forces about the IP and MTP joints, secondary to:

  • Toe crowding in ill-fitting footwear leading to chronic shortening of the flexor tendons and eventual flexion contracture
  • Traumatic injury to the:
    • Terminal extensor tendon of the extensor expansion resulting in reduction of extensor forces and predominance of flexor tone at the DIP joint, or
    • Metatarsal/plantar plate resulting in dorsal subluxation of the MTP joint and predominant flexor tone at the IP joints
  • Chronic synovitis leading to injury of the terminal extensor tendon, sagittal bands, and/or metatarsal/plantar plate.
  • Neurologic disease, such as:
    • Peripheral neuropathy and associated intrinsic foot muscle weakness. The foot intrinsic muscles are responsible for flexion at the MTP joint and extension at the IP joints. Weakness of the foot intrinsic muscles with preservation of the long flexor tone leads to the predominance of MTP extension and IP flexion forces that result in claw toe.
    • Spasticity leading to increased tone in the extrinsic muscles of the foot—the long flexors/extensors which overpower the small intrinsic muscles of the foot and have the combined effect of extension at the MTP joint and flexion at the IP joints
  • Long flexor tendon contracture as a complication of posterior leg compartment syndrome

Risk-Factors

  • Constricting footwear—high heels, narrow and shallow toe box
  • Abnormally long metatarsal and/or toe, relative to adjacent ray
  • Neuromuscular disorders (more commonly associated with claw toe deformity), such as:
    • Peripheral neuropathy (e.g., secondary to diabetes mellitus and Charcot-Marie-Tooth disease)
    • Muscular dystrophies
    • Equinovarus associated with spasticity and/or dystonia (e.g., with stroke, cerebral palsy)
  • Inflammatory joint disease
  • Older age
  • High body mass index
  • Acute trauma

General Prevention

Avoidance of constrictive footwear

Diagnosis ⬆ ⬇

History

  • Trauma
  • Personal or family history of neuromuscular disorder
  • Risk factors for peripheral neuropathy: diabetes mellitus, alcohol abuse, renal failure

Physical Exam

  • Inspect for:
    • Toe deformity and position of the MTP, PIP, and DIP joints. Observations should be made in the weight-bearing and non–weight-bearing position.
    • Signs of abnormal pressure: callous formation (usually dorsal IP joints, at the tip of the toe or at the metatarsal heads on the plantar surface), skin ulcers, injury to nails.
    • Other associated foot/toe deformities: equinovarus, pes planus/cavus, hallux valgus, under-riding or over-riding toes.
    • Gait evaluation: Observe for antalgic gait. Often times, spasticity is more pronounced during ambulation.
    • Palpate to assess for
      • The point of maximal tenderness to guide the need for pressure relief.
      • The presence or absence of synovitis.
      • Joint range of motion.
      • Flexible versus fixed deformity. This may be assessed by passively ranging the MTP and/or IP joints or by moving the ankle into plantar flexion and observing for resolution of hammer or claw toe deformities. Alternatively, dorsally directed pressure on the plantar surface of the involved metatarsal may reduce a flexible hammer toe deformity (push up test).
      • Heel cord tightness using the Silfverskiold test.
      • Neurovascular integrity and muscular tone.
  • Examination considerations:
    • Patients should be examined in weight-bearing and non–weight-bearing positions because MTP extension may be more manifest during weight-bearing.
    • Similarly, hammer and claw toe deformities may be less apparent with ankle plantar flexion. Ankle equinus should be manually corrected and the toes reexamined for deformity in this position.
    • It is important to distinguish between flexible versus fixed deformity. If a deformity is completely correctable with manipulation, it is typically considered a “flexible” deformity. Flexible deformities are more likely to respond to nonoperative measures. Fixed deformities are more likely to require surgery.

Diagnostic Tests & Interpretation

Initial Tests (lab, imaging)

  • Imaging is typically not necessary to make a diagnosis. When obtained, weight-bearing x-rays of the feet—anteroposterior (AP), lateral, and oblique—should
    • Confirm the presence of IP joint deformity and
    • Identify other associated foot abnormalities (e.g., MTP joint subluxation).
  • Consider rheumatologic workup as guided by the clinical index of suspicion: erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), complete blood count (CBC), rheumatoid factor (RF), and antinuclear antibody (ANA).
  • Advanced imaging—bone scan or magnetic resonance imaging (MRI)—may be indicated in cases of ulceration with suspected underlying osteomyelitis.

Diagnostic Procedures/Other

  • Nerve conduction study and electromyography (NCS/EMG) may be useful in the workup for neuromuscular causes.
  • Motor nerve blocks with local anesthetic may be helpful in distinguishing between spasticity and contracture.

Treatment ⬆ ⬇

General Measures

  • Patient education about shoe selection/modification—flat/low heel, wider, and taller toe-box and adequate length (1)[C]. A good rule of thumb is, there should be a circumference of 1 cm around the foot and at the distal tip of the toes when standing on the insole.
  • Orthotics/measures to reduce flexible deformities (e.g., Budin splint, figure of 8 taping) (1,2)[C]
  • Other pressure relief measures:
    • Toe sleeves, typically with foam padding to relieve pressure over the dorsal toe
    • Toe crests relieve pressure at the tip of the toes.
    • Metatarsal pads relieve pressure under the metatarsal heads.
    • Rocker bottom sole can help reduce forefoot pressure during gait (3)[C].
  • Attention to nail care and callous trimming, as necessary

Medication

  • Oral analgesics for pain—acetaminophen, nonsteroidal anti-inflammatory drugs (NSAIDs)
  • Chemodenervation/neurolysis:
    • Alcohol or phenol neurolysis (e.g., tibial nerve motor branch block to treat equinus)
    • Botulinum toxin injection at muscle motor points in the flexor digitorum longus (FDL) and flexor hallucis longus and brevis (FHL and FHB) muscles (4)[B]
  • Medication considerations:
    • Exercise the usual precautions in cases of known liver, renal, gastrointestinal, pulmonary, or cardiac disease.

Issues for Referral

  • Surgery may be indicated when nonoperative treatment is unsuccessful in relieving symptoms.
  • The acute onset of toe deformity or pain, particularly in the athlete or in the presence of associated trauma, should lead to more prompt and urgent evaluation by a surgeon.

Additional Therapies

Consider prescribing exercises for heel cord stretching (in subtalar neutral) and foot core strengthening as clinically indicated.

Surgery/Other Procedures

  • Differentiation between flexible and rigid deformity must be incorporated into surgical planning:
    • Flexible hammer/claw toes may be repaired with flexor and extensor percutaneous tenotomies (1)[C].
    • Flexible mallet toes may be treated with percutaneous release of the FDL tendon (1)[C].
    • Transfer of the FDL tendon to the extensor mechanism is an option in some flexible deformities (1,5)[C].
    • Rigid deformities often require a capsulotomy or treatment with arthroplasty (joint resection) or arthrodesis (joint fusion) (5)[C].
  • Involvement of the MTP joint may require additional soft tissue (i.e., capsulotomy, collateral ligament release, plantar plate repair) and/or bony (i.e., shortening osteotomy) procedures.

Ongoing Care ⬆ ⬇

Follow-up Recommendations

In the absence of any pressing surgical indication (e.g., acute trauma or competitive athlete), conservative treatment may be a long-term option given that the patient’s expectations are being met, and symptoms do not create significant interruption in activities of daily living (ADLs).

Prognosis

  • Surgery may be unnecessary if conservative treatment is started early.
  • Postoperative recovery time varies depending on the complexity and invasiveness of the procedure.
  • Most patients are allowed to bear weight through the heel immediately following surgical intervention.
  • Return to activity is highly dependent on the type of procedure performed. For example, after plantar plate repair, return to play may be delayed for 3 mo following surgery.

Complications

  • Fixed toe deformity
  • Toenail injury
  • Callous formation
  • Ulceration with the potential for osteomyelitis
  • If surgery is performed:
    • Excessive shortening of the toe may lead to poor motor control of the affected digit.
    • Excessive shortening of the metatarsal may lead to a floating toe in addition to causing transfer metatarsalgia (adjacent metatarsal pain).
    • Persistent numbness of the toe and surrounding areas may occur as a result of nerve injury.
    • FDL tendon transfer results in the inability to actively flex the affected toe.

Additional Reading ⬆ ⬇

  • Hagedorn TJ, Dufour AB, Riskowski JL, et al. Foot disorders, foot posture, and foot function: the Framingham foot study. PLoS One. 2013;8(9):e74364.
  • Hannan MT, Menz HB, Jordan JM, et al. High heritability of hallux valgus and lesser toe deformities in adult men and women. Arthritis Care Res (Hoboken). 2013;65(9):1515–1521.
  • Laurent G, Valentini F, Loiseau K, et al. Claw toes in hemiplegic patients after stroke. Ann Phys Rehabil Med. 2010;53(2):77–85.

References ⬆ ⬇

  1. Frey-Ollivier S, Catena F, Hélix-Giordanino M, et al. Treatment of flexible lesser toe deformities. Foot Ankle Clin. 2018;23(1):69–90.
  2. Federer AE, Tainter DM, Adams SB, et al. Conservative management of metatarsalgia and lesser toe deformities. Foot Ankle Clin. 2018;23(1):9–20.
  3. Malhotra K, Davda K, Singh D. The pathology and management of lesser toe deformities. EFORT Open Rev. 2017;1(11):409–419.
  4. Lim EC, Ong BK, Seet RC. Botulinum toxin-A injections for spastic toe clawing. Parkinsonism Relat Disord. 2006;12(1):43–47.
  5. Shirzad K, Kiesau CD, DeOrio JK, et al. Lesser toe deformities. J Am Acad Orthop Surg. 2011;19(8):505–514.

Clinical Pearls ⬆

  • Remember: The joint will deform or pull to the strong (intact) side.
  • Injecting botulinum toxin to both the long and the short flexors of the toes is well tolerated and efficacious in the treatment of toe clawing from spasticity, allowing for lower dosages to be used than injecting the long flexors alone.
  • Surgery for cosmesis alone should be strongly discouraged.