PIP Joint 1

PIP JOINT 1
PIP JOINT Injuries

In general, the PIP is a critically important joint for finger function. It has a particular propensity to get stiff after injury, and even if uninjured but immobilized for a separate injury.

Anatomical Features

– the collateral ligaments allow for 7o-10o of lateral deviation, and slight rotation.
– unlike in the MCPs, the collaterals in the PIP are tight in all ranges of flexion/extension. Immobilization in flexion is to be avoided if possible.
– flexion is usually to 110-115o.
– the volar plate is robust and has a strong distal attachment to the base of the middle phalanx – this prevents hyperextension of the PIP (note that this is unique to the PIP – the DIP and MCP both can hyperextend).

Collateral Ligament Injuries

– when assessing the painful, injured PIP, an attempt must be made to ascertain where the maximal tenderness is – laterally, volarly, or dorsally. Pain on hyperextension is reflective of volar plate injury.
– after appropriate analgesia, stress testing should be performed – greater than 20o of angulation is indicative of complete collateral ligament rupture.

Treatment
The authors of Rockwood and Green, although they demonstrate a distinction between complete and partial tears of the ligament, do not treat them much differently. For either injury, their recommended treatment is buddy taping and immediate range of motion, for a period of 2-6 weeks (with complete tears at the longer end of the spectrum).
– They do point out that some authors feel that the complete injuries should be immobilized, while others feel that they should be operated on!

Dorsal PIP Dislocations (Volar Plate Injuries)

As PIP dislocations often are reduced in the field, it is important to determine the direction of dislocation, as the treatment for dorsal dislocations is different from volar. Dorsal dislocations are far more common, however. The volar plate always ruptures in dorsal dislocations.
The joint may be irreducible due to entrapment of the volar plate (most commonly), flexor tendon, or buttonholing of the proximal phalanx between the flexor tendons.

Treatment – Acute Injuries
Closed reduction and buddy taping for 3-6 weeks.
– Again, the authors comment that others immobilize the joint in about 15o of flexion for 2-3 weeks. They feel, however, that the trend is towards early motion and feel that if the finger is splinted to a normal digit, hyperextension instability is unlikely.

Treatment – Chronic Injuries
Chronic hyperextension is rare; occasionally a swan neck deformity may develop – these are treated with an operation to shorten the volar plate and prevent the hyperextension.
Flexion contracture is more common, secondary to scarring at the volar plate – these are treated with physio, and if intractable, surgical release.
Eaton has described a collateral ligament release for the stiff PIP.

Volar PIP Dislocations

These are rare. The central slip must be disrupted, and thus, the potential for a boutinniere deformity is present.
The danger is mistaking these PIP injuries for the more common dorsal dislocation – if one treats it as a dorsal dislocation with either buddy taping and motion or a period of immobilization in flexion, the lateral bands will be allowed to slip volarly and a boutinniere deformity will develop.

Treatment
Closed reduction and immobilization of the PIP in full extension for 4-6 weeks, allowing passive flexion and extension of the DIP. (This is basically the treatment for a closed boutinniere lesion / central slip rupture). Immobilization of the PIP in extension can be accomplished with a K-wire also.

Rotatory PIP Subluxation

These are often confused with volar dislocations.
Occurs with a twisting force that dorsally subluxes one of the condyles of the proximal phalanx up through the extensor hood between the central slip and lateral band, both of which remain intact (thus making it different from a volar dislocation where the central slip is torn).

Treatment
Closed reduction is