What are the pollex and hallux?

Pollex and Hallux: Anatomical Definitions and Clinical Significance

The pollex refers to the thumb (first digit of the hand), while the hallux refers to the big toe (first digit of the foot). These terms are derived from Latin and are commonly used in medical and anatomical contexts.

Anatomical Characteristics

Pollex (Thumb)

• The pollex is the first digit of the hand
• Distinguished by its opposable nature, allowing it to touch all other fingers
• Contains two phalanges (proximal and distal) rather than three as in other fingers
• Has two sesamoid bones at the metacarpophalangeal joint
• Fracture of the sesamoid bones can occur due to violent hyperextension or abduction 1

Hallux (Big Toe)

• The hallux is the first digit of the foot
• Contains two phalanges (proximal and distal)
• Has two sesamoid bones (medial and lateral) beneath the first metatarsal head
• Plays a crucial role in weight-bearing and gait

Clinical Significance

Hallux-Related Conditions

1. Hallux Valgus

   • Lateral deviation of the hallux at the metatarsophalangeal joint
   • Can be post-traumatic, following foot injury 2
   • Evaluation includes weightbearing AP, lateral, and sesamoid axial radiographs

2. Hallux Rigidus

   • Osteoarthritis of the first metatarsophalangeal joint
   • Treatment options include:
     • Joint arthroplasty for neuropathic hallux ulcers when non-surgical offloading fails 3
     • Hemiarthroplasty (replacement of the base of the proximal phalanx) 4

3. Diabetic Foot Complications

   • The hallux is a common site for diabetic foot ulcers
   • Assessment includes checking for limited joint mobility 3
   • Neuropathic hallux ulcers may require joint arthroplasty when non-surgical offloading fails 3

Pollex-Related Conditions

1. Pollex Valgus

   • Ulnar instability of the metacarpophalangeal joint of the thumb
   • Can result from injury to the ulnar collateral ligament and supporting structures 5

2. Pollex Flexus Congenitus

   • Congenital flexion anomaly in the interphalangeal joint
   • Characterized by a hard, palpable knot in the long flexor tendon 6

Clinical Assessment

Foot Examination

• Comprehensive foot examination should be performed annually for patients with diabetes 3
• Inspection should include assessment of the hallux for deformities, ulcers, or calluses
• The probe-to-bone test can help diagnose osteomyelitis when performed over the hallux 3

Imaging

• Plain radiographs are often sufficient for initial evaluation
• MRI is useful for assessing soft tissue conditions and bone marrow edema
• CT may be useful to confirm suspected sesamoid stress fractures 3

Treatment Considerations

For Diabetic Foot Ulcers

• Non-removable knee-high offloading devices are recommended for neuropathic plantar forefoot ulcers 3
• Digital flexor tenotomy is recommended for neuropathic plantar or apex ulcers on digits 2-5 3
• Joint arthroplasty should be considered for neuropathic hallux ulcers when non-surgical offloading fails 3

For Hallux Rigidus

• Hemiarthroplasty has shown good results with significant improvement in pain and function 7, 4

In summary, understanding the anatomical and clinical aspects of the pollex and hallux is essential for proper diagnosis and management of conditions affecting these digits, particularly in patients with diabetes or other systemic conditions that affect the extremities.