Modern Study Review (AI-Generated)
High-Yield Summary
Middle phalanx fractures are relatively uncommon but clinically significant due to their impact on finger function, particularly at the proximal interphalangeal (PIP) joint. Acceptable angulation thresholds are higher than for other phalangeal fractures because limited distal interphalangeal (DIP) motion is less functionally impairing. Intra-articular fractures involving the base of the middle phalanx often disrupt the extensor mechanism, leading to boutonniere deformity, which requires prompt recognition and appropriate management to restore finger extension and prevent chronic stiffness.
Key Diagnostic Findings
| Aspect | Details |
|---|---|
| Anatomy | Middle phalanx with PIP and DIP joints; extensor mechanism includes central slip and lateral bands |
| Clinical Presentation | Pain, swelling localized to middle phalanx; PIP joint tenderness; inability to extend PIP in boutonniere injury |
| Imaging | Standard AP, lateral, and oblique finger X-rays; look for shaft angulation, intra-articular fragments, and avulsions |
| Classification Systems | No formal universal classification; focus on fracture location (shaft vs. base), displacement, and extensor mechanism involvement |
Current Gold Standard Treatment
| Fracture Type | Treatment Indications |
|---|---|
| Diaphyseal (shaft) fractures | Non-operative: splinting with adjacent finger immobilization including PIP and DIP joints; early motion encouraged to prevent stiffness. Operative: rare, reserved for unstable or significantly displaced fractures. |
| Intra-articular base fractures | Non-operative: small dorsal chip fractures without displacement managed with splinting. Operative: large fragments, volar lip fractures with dorsal dislocation, or collateral ligament avulsions require open reduction and internal fixation (ORIF) and ligament repair. |
| Boutonniere deformity (central slip injury) | Non-operative: PIP extension splinting for 5-6 weeks with immediate DIP flexion to prevent stiffness. Operative: indicated for large fracture fragments or failed conservative treatment, involving repair of central slip and triangular ligaments. |
Modern Complications & Outcomes
- Complications:
- Chronic boutonniere deformity with PIP flexion contracture and DIP hyperextension
- Joint stiffness and loss of motion, especially at PIP joint
- Tendon adhesions limiting finger mobility
- Malunion with cosmetic deformity (rotational or angulatory)
- Outcomes:
- Early motion protocols improve functional recovery and reduce stiffness
- Surgical repair of extensor mechanism injuries improves extension and prevents deformity
- Acceptable angulation up to 15° in any plane generally does not impair function significantly
- Functional goals focus on pain-free motion and restoration of PIP joint extension
Classic Clinical Notes
Middle Phalanx #’s
- Fractures of the middle phalanx are uncommon.
- Shaft fractures are often associated with an element of crush.
- 10° to 15° of palmar or dorsal angulation is probably acceptable because the subsequent limitation of DIP motion is not as functionally damaging as similar limitation of the PIP or MCP joints.
- Similar amounts of frontal angulatory or rotational deformity are more cosmetically noticeable, but no more functionally damaging.
Diaphyseal Fractures
- 10° to 15° of angulation is acceptable, in any plane (sagittal, coronal, rotational).
Treatment
- Splinting to adjacent fingers, immobilizing both the PIP and DIP; tendon adherence is a reality, so early motion is advised if possible.
Intra-articular Fractures of the Base
- These are either dorsal chip fractures representing an avulsion of the central slip creating a boutonniere deformity, a volar lip fracture with a dorsal dislocation, or a lateral chip fracture representing a collateral ligament avulsion.
Boutonniere Injuries
- Caused by disruption of the central slip and tearing of the triangular ligaments that hold the lateral bands, thus allowing the lateral bands to slip below the PIP axis and cause a flexion deformity of the PIP, while extending the DIP.
- Acutely, the diagnosis is made clinically.
- Usually presents with swelling of the PIP joint, with tenderness primarily over the dorsum of the joint, rather than along the collaterals. It may be difficult to actively extend the PIP joint.
Treatment
- Without fracture, a closed boutonniere lesion should be treated closed, with the PIP joint splinted in full extension for 5-6 weeks, allowing active and passive DIP flexion immediately (while keeping the PIP extended).
- If there is a large fracture fragment, it should be opened and fixed, with repair of the triangular ligament to correct the volar subluxation of the lateral bands.
Last Updated on January 24, 2026 by orthonet
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