- 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.
Year Book: Chip Avulsions and Ruptures of the Palmar Plate in the PIP
Management of fracture dislocation of the proximal interphalangeal joints by extension block splinting.
Fracture dislocations of the proximal interphalangeal joint.