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Stability and constraint of the proximal interphalangeal joint
Y Minamikawa1, E Horii, P C Amadio
1Orthopedic Biomechanics Laboratory, Mayo Clinic, Rochester, Minn. 55905.
The Journal of Hand Surgery
|March 1, 1993
Summary
The collateral ligament is key for proximal interphalangeal joint stability. Testing for joint laxity in slight flexion is crucial to avoid false-negative results in lateral stress tests.
Area of Science:
- Orthopedics
- Biomechanics
- Hand Surgery
Background:
- The proximal interphalangeal (PIP) joint is crucial for hand function.
- Understanding its lateral stability is vital for diagnosing injuries.
Purpose of the Study:
- To quantify the lateral stability of the intact proximal interphalangeal joint.
- To determine the role of the collateral ligament in maintaining PIP joint stability.
- To evaluate the effectiveness of the lateral stress test in diagnosing collateral ligament injuries.
Main Methods:
- Kinematic analysis of 12 cadaver index fingers using an electromagnetic tracking system.
- Sequential sectioning of collateral ligaments under controlled lateral stress.
- Measurement of joint angulation (adduction and supination) during flexion/extension.
Main Results:
- Intact PIP joints exhibited 5° adduction and 9° supination under lateral stress.
- Maximum lateral angulation reached 15° with 1 kg force.
- Total collateral ligament sectioning increased angulation to 20°.
- Joint laxity decreased in full extension, flexion, and under muscle load.
- The PIP joint remained stable with half the collateral ligament intact.
Conclusions:
- The collateral ligament is the primary stabilizer of the proximal interphalangeal joint against lateral stress.
- A lateral stress test performed in 20-30° of flexion can help avoid false-negative results.
- Angulation exceeding 20° indicates collateral ligament compromise.