Bunnell Test (or Bunnell–Littler Test) is used to determine whether flexion restriction of the proximal interphalangeal joint PIP is due to tightness of the intrinsic muscles or due to a restriction of the metacarpophalangeal joint capsule.
How is Bunnell Test Performed?
This test is done in two stages, metacarpophalangeal joint MCP extension and flexion:
The metacarpophalangeal joint is stabilized in extension and the proximal interphalangeal joint is tried to flex and the degree of flexion is noted.
Then the metacarpophalangeal joint is flexed and again the degree of flexion of proximal interphalangeal joint is noted.
What does a positive Bunnell Test mean?
We differentiate 3 cases:
If the PIP flexion is increased, the pathology is intrinsic muscle contracture (Intrinsic tightness) as the intrinsic get released on MCP flexion.
If the PIP flexion is decreased, the pathology is extensor tendon contracture (extrinsic tightness) which is stretched further on MCP flexion.
If the PIP flexion is the same in both situations, the pathology is articular changes such as joint stiffness, tendon adhesions, and tenosynovitis
Increased pressure in the fascial compartments of the hand produces a typical deformity with slight flexion in the metacarpophalangeal joints, extension in the proximal and distal interphalangeal joints, intensification of the transverse arch of the hand, and adduction of the thumb (intrinsic plus deformity).
Clinical Tests for the Musculoskeletal System 3rd Edition.
Dutton’s Orthopaedic Examination, Evaluation, And Intervention 3rd Edition.
Sarvdeep S. Dhatt, Sharad Prabhakar – Handbook of Clinical Examination in Orthopedics