After extensor tendon repair of a finger, is it acceptable to allow active motion at the proximal interphalangeal (PIP) joint while immobilizing the distal interphalangeal (DIP) joint?

Active PIP Motion After Extensor Tendon Repair

Yes, active motion at the PIP joint is acceptable and recommended after extensor tendon repair, provided the DIP joint remains continuously immobilized in extension. 1

Evidence-Based Rationale

The American Academy of Orthopaedic Surgeons explicitly recommends beginning active finger motion exercises of the PIP and MCP joints immediately while keeping the DIP splinted to prevent stiffness. 1 This approach is supported by biomechanical evidence demonstrating that joint motion proximal to the DIP joint does not cause tendon gap formation at the repair site. 2

Key Biomechanical Principles

• Cadaveric studies confirm that PIP and MCP motion does not compromise DIP-level repairs. In 32 cadaveric fingers with mallet lesions, repeated flexion and extension of joints proximal to the DIP joint (including the PIP joint) did not cause any tendon gap when the DIP was properly immobilized. 2

• Wrist position matters more than PIP motion. The critical factor is maintaining the wrist in neutral to mild extension (not flexion), as wrist flexion combined with MCP flexion can create small gaps (0.9-2.0 mm) even with proper DIP immobilization. 3 However, PIP motion alone does not produce this effect.

Immobilization Protocol

Only the DIP joint requires immobilization for mallet finger or zone I extensor injuries:

• Splint the DIP joint in 5° hyperextension 3
• Keep the wrist in neutral to mild extension 3
• Allow free active motion of the PIP and MCP joints immediately 1

Critical warning: Even brief removal of the DIP splint restarts the entire healing timeline. 1 Patients must understand that uninterrupted immobilization of the DIP joint is mandatory for 6-8 weeks, while proximal joints should move to prevent stiffness.

Zone-Specific Considerations

For zone III injuries (PIP-level central slip injuries), the protocol differs:

• The PIP joint itself requires immobilization in 0° extension (full extension, not hyperextension) 3
• The DIP joint should remain free to move 3
• This prevents boutonnière deformity development 4

Clinical Pitfalls to Avoid

• Do not immobilize the PIP joint for DIP-level (zone I) injuries – this causes unnecessary stiffness without improving healing 2
• Do not allow wrist flexion during rehabilitation – maintain neutral to slight extension 3
• Monitor for unremitting pain during immobilization, which warrants immediate re-evaluation 1