Evaluation and Diagnosis of Foot Pathologies

• Pes Planus (Flat Foot): Characterized by a lowered medial longitudinal arch, calcaneal eversion, and talar adduction/plantarflexion. This is often linked to weakness in the tibialis posterior, tibialis anterior, or toe flexors.
• Pes Cavus (High Arch): Characterized by a high medial longitudinal arch, calcaneal inversion, and talar abduction/dorsiflexion. This structure reduces shock absorption, increasing the risk of metatarsalgia and plantar fasciitis.

Forefoot Alignment and Toe Deformities

The alignment of the forefoot and individual toes provides significant diagnostic clues:

• Hallux Valgus: A gradual subluxation of the 1st MTP joint (angle $> 20^\circ$) that results in a medial bunion.
• Morton’s Toe: Occurs when the 1st metatarsal is shorter than the 2nd metatarsal, causing the 2nd toe to extend beyond the great toe.
• Claw Toes: Characterized by hyperextension of the MTP joints and flexion of the PIP and DIP joints, often due to contractures of the interosseous or lumbrical muscles.
• Hammer Toes: Characterized by hyperextension of the MTP and DIP joints with flexion of the PIP joint.

Manual Assessment

Beyond visual inspection, clinicians must perform Manual Muscle Testing (MMT) to assess the strength of the toe flexors and extensors, such as the flexor hallucis longus/brevis and flexor digitorum longus/brevis. Additionally, assessing subtalar neutral is essential to determine the baseline position of the subtalar joint.

Exam Tip: When evaluating forefoot alignment, distinguish between forefoot varus (inward tilt) and forefoot valgus (outward tilt). These can be uncompensated or compensated by the subtalar joint.

Gait and Biomechanical Analysis

Gait evaluation involves observing the patient's movement patterns during both walking and running to identify compensations for impairments.

The Walking Gait Cycle

Walking is divided into two primary phases:

1. Stance Phase (Weight-Bearing): This includes initial contact (heel strike), loading response (flat foot), midstance, terminal stance (heel off), and preswing (toe off). During these stages, muscle groups like the quadriceps, hamstrings, and plantarflexors act eccentrically or concentrically to maintain stability and propulsion.
2. Swing Phase (Non-Weight-Bearing): This includes initial swing (limb acceleration), midswing (toe clearance), and terminal swing (limb deceleration).

The Running Gait Cycle

Running differs significantly from walking due to higher mechanical demands:

• Presence of a flight/float phase.
• Absence of a double-limb support period.
• Significantly higher ground reaction forces (GRFs), reaching $2\text{--}6 \times$ body weight.

Impairments and Compensations

Pathologies often trigger compensatory movements to maintain efficiency or avoid pain:

• Decreased Dorsiflexion: May lead to increased subtalar pronation or a premature heel raise.
• Muscle Weakness: Weakness in the hip flexors can result in compensatory hip elevation to achieve necessary toe clearance during the swing phase.
• Hip Rotator Weakness: Often results in a "toe-in" gait.

Clinical Case Applications

Plantar Fasciitis

Commonly presenting with insidious onset, patients often report pain near the medial calcaneal tubercle that is most severe during the first steps in the morning. Risk factors include obesity, pes planus/cavus, and triceps surae tightness.

Metatarsal Fractures

Often referred to as "march fractures" in military populations, these can result from repetitive stress or direct trauma. A Jones fracture specifically involves the fifth metatarsal and may require surgical fixation (intramedullary screw) for elite athletes.

Intermetatarsal Neuroma

This involves inflammation of the plantar nerve, most commonly between the 3rd and 4th metatarsals. Patients often describe a sensation of a "rock in the shoe" and may exhibit a positive Mulder sign during examination.