Measuring Joint Flexibility in Hallux Rigidus Using a Novel Flexibility Jig.

Area of Science:

• Orthopedics
• Biomechanics
• Foot and Ankle Surgery

Background:

• Hallux rigidus (HR) is a degenerative condition affecting the first metatarsophalangeal (MTP) joint.
• Limited research exists on the flexibility of the MTP joint in HR patients.
• Assessing joint flexibility, beyond range of motion, may offer valuable insights into HR assessment.

Purpose of the Study:

• To evaluate and compare the flexibility of the first MTP joint in patients with hallux rigidus (HR) versus healthy controls.
• To introduce and validate a novel flexibility device for assessing MTP joint flexibility.

Main Methods:

• A prospective comparative study involving 15 patients with Coughlin stage II or III HR and 20 healthy controls.
• A custom flexibility jig was used by two raters to perform seated and standing tests, measuring dorsiflexion angle and applied torque.
• Statistical analysis included t tests for group and positional differences and intraclass correlation coefficients (ICCs) for reliability.

Main Results:

• HR patients were older and had reduced maximum dorsiflexion compared to controls.
• HR patients demonstrated significantly reduced flexibility in early motion, laxity angle, and torque angle.
• After age adjustment, only laxity angle remained a significant differentiator between HR patients and controls.
• Joint flexibility was generally greater in the seated position, particularly for HR patients.
• The flexibility assessment demonstrated good to excellent intra- and interrater reliability (ICC ≥ 0.60).

Conclusions:

• A novel flexibility device reliably assesses first MTP joint flexibility in hallux rigidus (HR) patients.
• Patients with HR exhibit significantly decreased first MTP joint flexibility compared to healthy individuals.