Evaluation of first ray instability using the double dorsiflexion test: A prospective observational case-controlled...

Area of Science:

• Orthopedics
• Biomechanics
• Podiatry

Background:

• First-ray (FR) stability is crucial for foot propulsion, supporting 60% of body weight during stance.
• First-ray instability (FRI) is linked to middle column overload, synovitis, deformity, and osteoarthritis.
• Clinical detection of FRI can be challenging, necessitating improved diagnostic methods.

Purpose of the Study:

• To develop and validate a clinical test for identifying first-ray instability (FRI).
• To assess the efficacy of a novel double dorsiflexion (DDF) maneuver in detecting FRI.

Main Methods:

• A prospective case-controlled study involving 10 patients with unilateral FRI and their unaffected contralateral feet.
• Direct measurement of first metatarsal head translation using a Klaumeter.
• Assessment of first metatarsophalangeal (MTP) joint dorsiflexion range of motion (ROM) with and without dorsal force application using motion analysis software.

Main Results:

• FRI feet exhibited significantly greater dorsal translation (median 11.94 mm) compared to controls (median 1.77 mm).
• The double dorsiflexion (DDF) test showed a mean reduction in dorsiflexion ROM of 67.98% in FRI feet versus 28.44% in controls (P < 0.01).
• A >50% decrease in MTP joint dorsiflexion ROM during the DDF test demonstrated 90% sensitivity and 100% specificity for identifying FRI (AUC = 0.990).

Conclusions:

• The double dorsiflexion (DDF) test is a simple, effective clinical maneuver for diagnosing first-ray instability (FRI).
• This method avoids the need for complex instrumentation or radiation-based assessments.
• A >50% reduction in proximal phalanx motion during the DDF test reliably indicates FRI with high sensitivity.