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Dorsal Fracture Dislocations of the PIP Joint


- See:
      - Dorsal Dislocation of PIP joint
      - Extension Block Casting
      - Phalangeal Injury

- Discussion:
    - long moment arm of the PIP joint, places this joint for higher risk of this injury;
    - mechanism and anatomy of injury:
          - results from a jamming type injury or PIP joint hyperextension (which avulses the volar plate - either as a ligamentous injury or as a palmar lip fracture);
          - central slip of extensor apparatus pulls middle phalanx dorsally & proximally;
          - complete dorsal dislocation indicates disruption of volar plate (distal insertion) & accessory collateral ligaments;
          - proper collaterals may remain attached to the middle phalanx and become lax as middle phalanx is displaced dorsally;
    - differential dx of pip injuries:
    - stable vs. unstable injuries:
          - stable frx: small fracture w/ less than 40% of the middle phalanx base
          - unstable frx: frx involves > 40% joint surface;
                 - palmar lip fracture
                 - dorsal lip fracture
                 - pilon fracture

- Radiographs:
    - true lateral x-rays of the involved finger are manditory;
    - radiographs can misleadingly suggest that very simple frx has occured w/ only small fragment of the bone involved;
         - this fragment, however, is often the major attachment of a collateral ligament, the volar plate, or a tendon;
                - this small frx may render joint grossly or potentially unstable;
         - distinguish avulsion chip frx from frx dislocations w/ significant PIP joint involvement;
    - determine amount of articular involvement:
         - when volar triangular frx frag of middle phalanx involves > 1/4 of articular surface, dorsal dislocation of middle phalanx may occur late because the volar plate and a significant portion of the collateral ligaments are attached to the small fragment;
         - base of middle phalanx may be frxed w/ upto 20 to 75% of joint involvement;
         - frx dislocation may involve > 50% of articular surface, however, it is usually 20 to 40%;
    - volar plate remains attached to fracture fragment, & therefore accessory collateral ligaments, volar plate, and fracture fragment maintain their normal relationships to each other;
    - V sign:
         - indicates inadequately reduced joint in which joint surfaces are neither parallel nor congruent;
         - a truly stable dislocation will not show instability in full extension;
         - hinged flexion:
                - this is a varient of the V sign in which congruent rotation of the joint is replaced by abnormal translation across the flattened frx segments;

- Exam:
    - following digital block anesthesia and reduction, have the patient actively move the joint and assess for subluxation as the digit moves into extension;
    - w/ palmar avulsion frx, note whether the injured digit permits hyperextension;
    - if the digit is allowed to remain in hyper-extension, swan neck deformity may eventually occur;

- Non Operative Treatment:
    - non operative treatment is generally indicated when there is less than 20-40 % of the palmar articular surface;
    - buddy taping:
         - avulsion frx arising from volar plate injuries usually heals w/ non operative rx;
         - reduction and brief splinting followed by buddy taping are indicated if anatomic reduction is maintained thru full ROM;
         - buddy taping helps to prevent hyper-extension for otherwise stable fractures;
         - it is important to not let the injured PIP joint fall into hyperextension, otherwise a swan neck deformity may result;
               - if necessary, a paper clip can be incorporated into a Coband wrap inorder to prevent hyperextension;
    - extension block casting
         - radiographs are required to determine the stable range of motion;
         - typically, as the digit moves from flexion to extension, subluxation will be evident on x-ray;
               - extension block spinting is used to prevent the digit from extending past the safe zone;
         - after reduction, keep joint in at least 10-30 deg of flexion w/ extension block casting;
         - w/ unstable dislocations, place joint in considerable flexion (about 75 deg);
               - if x-rays show joint well reduced and congruent, apply dorsal block splint, & gradually decrease amount of flexion over 1 month;

- Indications for Operative Treatment:
    - when the volar lip fracture of the middle phalanx involves 20-40% or more of the
          articular surface, the remainder of the middle phalanx subluxes dorsally;
          - this unstable injury requires more sophisticated treatment than simple volar plate avulsion;
    - unstable joint following reduction;
    - presence of bony fragment which blocks reduction;
    - pilon fractures: typically result in severe stiffness with non operative treatment;
    - residual subluxation:
           - manifested as the V sign on the lateral radiograph;
           - indicates inadequately reduced joint;
           - surfaces are neither parallel nor congruent;
           - patients who are left with residual subluxation will most likely end up having a poor result;

- Operative Treatment:
    - subluxation of the joint requires correction, but anatomic joint restoration is not manditory nor is it always possible;
           - correction of joint subluxation also requires correction of abnormal joint hinging and gliding;
    - anatomic reduction of comminuted volar lip fragments is not essential;
    - volar plate arthroplasty:
           - volar plate is the chief stabilizer is dorsal dislocations / dorsal disolation-fractures;
           - this procedure works best when the buttressing effect of the palmar lip remains intact;
    - extension block pinning:
           - several techniques have been described;
           - one technique involves insertion of a K wire into the head of the proximal phalanx with the remaining end protruding enough in order to block PIP extension;
           - intradigital traction fixation device;
                  Fracture-dislocation of the middle phalanx at the proximal interphalangeal joint: repair with a simple intradigital traction-fixation device.
    - external fixation:
           - provides distraction across the PIP joint and corrects residual dorsal subluxation;
           - intradigital traction fixation device:
                  - technique relies on the fact that distaction most often will reduce the fracture and restore the joint anatomy;
                  - use 0.045 inch pins;
                  - one pin is inserted transversely thru the distal half of the middle phalanx;
                  - the other pin is inserted transversely through the proximal phalangeal head, and both ends are bent 90 deg so that they are parallel to the middle phalanx;
                         - the distal ends of this pin are bent again about 5-8 mm distal to the first pin;
                         - a final bend is made about 5 mm distal to the previous bend;
                  - the second pin is used as the traction device, by hooking over the pin thru the middle phalanx;
                  - the patient is allowed PIP joint motion as tolerated;
    - open reduction without internal fixation:
           - indicated for osteochondral frx dislocation, in which the osteochondral frx is gently replaced back into the frx surface and the joint is carefully closed;
                  - no fixation is applied;
           - ref: Surgical management of osteochondral fractures of the phalanges and metacarpals: a surgical technique.  
    - arthrodesis:
           - with operative management of PIP fracture dislocations, as a back up plan, patients should always be consented for arthrodesis;

- Complications:
    - w/o proper care, joint becomes swollen, tender & unstable and eventually the joint will develop traumatic arthritis;
    - major disability is not instability but stiffness and pain

Extension block pinning for proximal interphalangeal joint fracture dislocations: preliminary report of a new technique.

The conservative management of volar avulsion fractures of the P.I.P. joint.

Unstable fracture dislocations of the proximal interphalangeal joint. Treatment with the force couple splint.

Year Book: Chip Avulsions and Ruptures of the Palmar Plate in the PIP

Unstable fracture dislocations of the proximal interphalangeal joint of the fingers: a preliminary report of a new treatment technique.

Management of fracture dislocation of the proximal interphalangeal joints by extension block splinting.

Fracture dislocations of the proximal interphalangeal joint.

Fracture-dislocation of the middle phalanx at the proximal interphalangeal joint: repair with a simple intradigital traction-fixation device.

Percutaneous, intramedullary fracture reduction and extension block pinning for dorsal proximal interphalangeal fracture-dislocations.