Middle Phalanx #’s

Fractures of the middle phalanx are uncommon. Shaft fractures are often associated with an element of crush. 10o to 15o 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

– 10o to 15o of angulation is acceptable, in any plane (sagittal, coronal, rotational).

– 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.

– 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.

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