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Basics

Deformities of digits 2 to 5 (“lesser” digits) of the foot

Description

  • Plantar flexion deformity of the proximal interphalangeal (PIP) joint with varying degrees of hyperextension of the metatarsophalangeal (MTP) and distal interphalangeal (DIP) joint; primarily in sagittal plane (1)
  • Can be flexible, semirigid, or fixed
    • Flexible: passively correctable to neutral position
    • Semirigid: partially correctable to neutral position
    • Fixed: not correctable to neutral position without intervention

Epidemiology

Most common deformity of lesser digits, typically affecting only one or two toes:

  • Second toe is the most commonly involved.
Incidence
  • Undefined
  • Increases with age, duration of deformity (from flexible to rigid)
Prevalence
  • Predominant sex: female > male (2)
    • Female predominance from 2.5:1 to 9:1, depending on age group
  • Can range from 1% to 20% of population studied
  • Blacks are more often affected than whites (2).

Etiology and Pathophysiology

  • Can be congenital or acquired
  • Biomechanical dysfunction results in loss of function of extensor digitorum longus (EDL) tendon at the PIP joint and the flexor digitorum longus (FDL) tendon at the MTP joint; the intrinsic muscles sublux dorsally as the MTP hyperextends. This results in plantar flexion of the PIP joint and hyperextension of the MTP joint (2).
  • Specific pathomechanics vary by etiology:
    • Toe length discrepancy or narrow footwear toe box induces PIP joint flexion by forcing digit to accommodate shoe.
      • May also lead to MTP joint synovitis secondary to overuse, with elongation of plantar plate and MTP joint hyperextension
    • Rheumatoid arthritis (RA) causes MTP joint destruction and resultant subluxation.
    • Any condition that compromises intra-articular and periarticular tissues, such as second ray longer than first, inflammatory joint disease, neuromuscular conditions, improper-fitting shoes, and trauma (3)
    • Damage to joint capsule, collateral ligaments, or synovia leads to unstable PIP joint or MTP joint.

Genetics
  • Significant heritability rates of 49–90% (4)
  • Specific genetic markers are not identified.

Risk Factors

  • Pes cavus, pes planus
  • Hallux valgus
  • Metatarsus adductus
  • Ankle equinus
  • Neuromuscular disease (rare)
  • Trauma; improperly fitted shoes (narrow toe box) and/or tight hosiery
  • Abnormal metatarsal and/or digit length
  • Inflammatory joint disease (e.g., RA)
  • Connective tissue disease
  • Diabetes mellitus

General Prevention

  • Proper fitting of shoes. Use of pressure-dispersive footwear helps reduce pain.
  • Foot orthoses modulate biomechanical dysfunction and muscular imbalance, preventing progression (2).
  • Control of predisposing factors (e.g., inflammatory joint disease) may also slow progression.

Commonly Associated Conditions

  • Hallux valgus
  • Cavus foot
  • Metatarsus adductus
  • Dorsal callus

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Citation

* When formatting your citation, note that all book, journal, and database titles should be italicized* Article titles in AMA citation format should be in sentence-case
TY - ELEC T1 - Hammer Toes ID - 117049 ED - Baldor,Robert A, ED - Domino,Frank J, ED - Golding,Jeremy, ED - Stephens,Mark B, BT - 5-Minute Clinical Consult, Updating UR - https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/117049/all/Hammer_Toes PB - Wolters Kluwer ET - 27 DB - Medicine Central DP - Unbound Medicine ER -