Proximal Interphalangeal Joint Fracture-Dislocation

Surgical Indications

Absolute Indications

• Joint irreducible by closed means (soft tissue interposition, typically volar plate or lateral band).
• Persistent dorsal subluxation (V-sign) despite flexing to 30 to 40 degrees.
• Unstable fracture pattern requiring more than 40 degrees of flexion to maintain reduction.
• Open fracture-dislocations.
• Chronic or missed fracture-dislocations (greater than 3 weeks).

Relative Indications

• Large, single volar fragment representing greater than 40 percent of the articular surface (amenable to ORIF).
• Patient inability to comply with a strict splinting and supervised therapy protocol.
• Significant articular step-off (greater than 2 mm) in a large, fixable fragment.

Contraindications

• Stable joint concentricity maintained in less than 30 degrees of flexion (manage with dorsal block splinting).
• Extremely sedentary patient with low functional demands (relative).
• Severe peripheral vascular disease or active infection in the digit.

Evidence for Treatment Modalities

Dorsal Block Splinting

• Indication: Stable fracture-dislocations (typically less than 30 percent of the articular surface).
• Protocol: Joint reduced and splinted in 20 to 30 degrees of flexion. Active flexion is encouraged immediately. The splint extension block is gradually reduced by 10 degrees per week.
• Outcomes: Excellent functional results if concentric reduction is maintained and early motion is initiated. The literature strongly supports non-operative management for stable patterns, showing comparable or superior outcomes to surgery due to the avoidance of surgical trauma and subsequent stiffness.

Extension Block Pinning

• Indication: Unstable joints where the fragment is too small or comminuted for ORIF, but the joint can be reduced in flexion.
• Technique: A K-wire is driven into the proximal phalanx head to mechanically block extension past the point of instability. Allows active flexion.
• Evidence: Provides reliable stability while permitting the crucial early flexion necessary for cartilage nutrition and preventing stiffness. Originally described by McElfresh, this technique remains a workhorse for unstable, unfixable dorsal fracture-dislocations.

Dynamic External Fixation (Suzuki / Compass Hinge)

• Indication: Highly comminuted, pilon type fractures of the middle phalanx base.
• Mechanism: Utilises ligamentotaxis to pull the comminuted fragments into alignment and distract the joint space, preventing collapse while allowing active motion.
• Outcomes: Associated with a high rate of pin-tract infections, but functional outcomes are generally good to excellent for otherwise un-reconstructable injuries. Studies show average arcs of motion of 70 to 80 degrees, which is highly functional for a pilon fracture.

Volar Plate Arthroplasty (Eaton)

• Indication: Comminuted volar base fractures or chronic fracture-dislocations where the volar restraint is lost.
• Mechanism: The fracture fragments are excised, and the volar plate is advanced into the defect and sutured into the middle phalanx to restore stability and provide a smooth gliding surface.
• Evidence: Reliable for restoring stability and preventing subluxation. Patients often lose 10 to 15 degrees of terminal extension, but this is a small price for a stable, pain-free, mobile joint.

Hemi-Hamate Autograft

• Indication: Large volar base defects (greater than 50 percent), acute or chronic, not amenable to primary repair.
• Mechanism: A graft taken from the distal articular surface of the hamate (which perfectly matches the concavity of the middle phalanx base) is fixed into the defect.
• Evidence: Technically demanding but can restore near-normal anatomy and motion in complex cases. Long-term studies show good graft incorporation and maintenance of joint space, though donor site morbidity (hamate pain) can occur.

Proximal Interphalangeal (PIP) Joint Anatomy

Bony Architecture

• Proximal Phalanx Head: Consists of two condyles separated by an intercondylar notch. It is wider volarly than dorsally. The condylar shape dictates the cam effect of the collateral ligaments.
• Middle Phalanx Base: Features two concave articular facets separated by a median ridge, perfectly matching the proximal phalanx condyles.
• The bony geometry provides inherent stability in the anteroposterior plane, acting as a hinge joint with a tight arc of motion (0 to 110 degrees).

Ligamentous Restraints

• Proper Collateral Ligaments (PCL): Origin from the dorsal aspect of the proximal phalanx head and insert into the volar-lateral base of the middle phalanx. Taut in flexion.
• Accessory Collateral Ligaments (ACL): Volar to the PCL, inserting into the volar plate. Taut in extension.
• Volar Plate: A thick, fibrocartilaginous structure that prevents hyperextension. It originates proximally from the proximal phalanx via the check-rein ligaments (which tether it to the periosteum) and inserts distally into the volar base of the middle phalanx.
• In a dorsal dislocation, the volar plate ruptures distally or avulses a bony fragment from the middle phalanx base. The check-rein ligaments generally remain intact.

The Extensor Mechanism

• The central slip inserts into the dorsal base of the middle phalanx, extending the PIP joint.
• The lateral bands diverge dorsally around the PIP joint, held in place by the transverse retinacular ligaments.
• Surgical Relevance: A dorsal approach splits the extensor mechanism and risks scarring, central slip attenuation, and an extensor lag. Volar base pathology is best addressed volarly to spare the extensor apparatus.

Neurovascular Bundles

• The proper digital arteries and nerves run volarly, lateral to the flexor tendon sheath.
• The vincula (longa and brevia) carry the blood supply to the flexor tendons.
• Surgical Relevance: In a Bruner or midaxial approach, these bundles must be identified and protected. They are often retracted with the volar skin flap in a Bruner approach, or identified early in a midaxial approach.

Flexor Tendon Sheath

• The flexor digitorum superficialis (FDS) bifurcates (Chiasma of Camper) over the proximal phalanx and inserts into the volar middle phalanx shafts.
• The flexor digitorum profundus (FDP) runs through the FDS bifurcation to insert on the distal phalanx.
• Surgical Relevance: The flexor tendons must be retracted laterally to access the volar plate and the fracture site. The A3 pulley over the PIP joint is often divided to facilitate exposure, but A2 (proximal phalanx) and A4 (middle phalanx) must be preserved to prevent bowstringing.

Positioning and Preparation

• Patient Position: Supine with arm on a radiolucent hand table.
• Tourniquet: Upper arm tourniquet applied and inflated to 250 mmHg.
• Anaesthesia: Regional block (axillary or supraclavicular) or General Anaesthesia. WALANT can be used for simpler pinning procedures but is less ideal for complex ORIF or arthroplasty due to the need for deep dissection and prolonged tourniquet-like haemostasis.
• Equipment: Mini C-arm (fluoroscopy), K-wires (1.1 mm and 1.6 mm), mini-fragment screw set (1.0 mm, 1.2 mm), rubber bands or suture for dynamic fixator, micro-sagittal saw (for hemi-hamate graft).

Technique 1: Extension Block Pinning

Step 1: Closed Reduction

Under fluoroscopy, apply longitudinal traction, flex the PIP joint, and reduce the subluxation. Assess the degree of flexion required to maintain a concentric joint. Ensure there is no V-sign on the true lateral view.

Step 2: Pin Placement

With the joint flexed beyond the unstable angle (for example, 40 degrees), insert a 1.1 mm K-wire dorsally into the head of the proximal phalanx.

• The pin should be angled distally to block the middle phalanx from extending past the point of stability.
• Ensure the pin does not cross the PIP joint space; it should only sit in the proximal phalanx.
• Confirm under fluoroscopy that the joint is concentrically reduced in the permitted arc of flexion, and that the pin successfully blocks extension. As the finger is extended, the dorsal base of the middle phalanx should abut the pin, stopping further extension and maintaining volar contact.

Step 3: Post-op Management

Cut the pin outside the skin and bend it to prevent migration. Apply a dorsal blocking splint incorporating the pin. Begin active flexion immediately to nourish the cartilage and prevent adhesions. The pin is typically removed in clinic at 3 to 4 weeks.

Technique 2: Open Reduction Internal Fixation (ORIF)

Step 1: Surgical Approach

Use a volar Bruner (zigzag) incision over the PIP joint, or a midaxial approach.

• Bruner: Elevate full-thickness flaps, preserving the neurovascular bundles within the flaps. Ensure the apices of the flaps reach the midaxial line.
• Flexor Sheath: Identify the A3 pulley over the PIP joint. Divide it longitudinally to expose the flexor tendons. Retract the FDS and FDP laterally with a Penrose drain.

Step 2: Joint Exposure

Identify the volar plate. In a fracture-dislocation, it will be attached to the avulsed volar base fragment.

• Hyperextend the joint (if possible and safe) or gently distract to visualise the fracture bed and the articular surface. Use a 'shotgun' approach by hyperextending the PIP joint to look directly down at the articular surfaces, taking care not to disrupt the collateral ligaments completely.
• Irrigate the joint to clear any haematoma or interposed soft tissue.

Step 3: Fracture Reduction and Fixation

Anatomically reduce the volar base fragment using a dental pick or small reduction forceps. The joint surface must be prioritised over the metaphyseal cortex.

• Temporarily hold the reduction with a 0.8 mm K-wire.
• Fix the fragment with one or two 1.0 mm or 1.2 mm lag screws. Ensure the screw heads are countersunk so they do not impinge on the flexor tendons or joint.
• If the fragment is highly comminuted, attempting ORIF will fail. Have a low threshold to convert to a volar plate arthroplasty.

Step 4: Closure

Check the reduction under fluoroscopy. The PIP joint must be concentrically reduced through a full arc of motion. Repair the flexor sheath (A3 pulley) if possible with fine absorbable suture, though leaving it open is acceptable if tension is too high. Let the flexor tendons fall back into place. Close the skin with non-absorbable sutures.

Technique 3: Volar Plate Arthroplasty (Eaton)

Step 1: Approach and Exposure

Perform a volar Bruner approach as described for ORIF. Retract the flexor tendons laterally. Identify the volar plate and the comminuted volar base fragments.

Step 2: Excision of Fragments

Excise the comminuted, un-reconstructable bony fragments from the volar base of the middle phalanx. Preserve the insertions of the collateral ligaments laterally if possible.

• Use a rongeur or fine burr to create a smooth, transverse trough at the volar base of the middle phalanx. This trough is where the volar plate will be advanced.

Step 3: Volar Plate Advancement

Release the check-rein ligaments proximally if the volar plate does not easily reach the trough.

• Pass two strong non-absorbable sutures (such as 2-0 or 3-0 Ethibond) through the distal margin of the volar plate using a grasping Krackow or Bunnell technique.
• Drill two small parallel holes from the volar trough dorsally through the middle phalanx, exiting slightly distal to the dorsal articular margin.
• Pass the suture ends through the drill holes to the dorsal aspect of the middle phalanx using a suture passer or straight needle.

Step 4: Reduction and Tying

Reduce the PIP joint concentrically. While holding the joint in 20 to 30 degrees of flexion, tie the sutures tightly over the dorsal cortex, or over a small button resting on the skin to prevent cutting through the bone.

• The volar plate is now advanced into the bony defect, restoring a smooth volar articular surface and providing a strong tether against dorsal subluxation.
• Pin the PIP joint in 20 to 30 degrees of flexion with a transarticular 1.1 mm K-wire for 2 to 3 weeks to protect the repair from early stretching.

Technique 4: Dynamic External Fixation (Suzuki Frame)

Step 1: Pin Placement

The most critical step is placing the proximal axis pin. Insert a 1.1 mm K-wire transversely through the true axis of rotation of the proximal phalanx head. This lies at the centre of the concentric circles forming the condyles on the lateral view.

• Insert a second 1.1 mm K-wire transversely through the middle phalanx, distal to the fracture site and safely away from the joint.

Step 2: Construct Assembly

Bend the ends of the proximal pin 90 degrees distally. Bend the ends of the distal pin 90 degrees proximally.

• Create small hooks at the ends of the pins.
• Apply elastic bands or specific dynamic traction devices between the hooks on each side of the finger to generate longitudinal traction.

Step 3: Assessment

Under fluoroscopy, ensure the traction distracts the joint space symmetrically and reduces the comminuted fragments via ligamentotaxis.

• Passively flex and extend the PIP joint to ensure concentric motion without subluxation. If the joint hinges open dorsally or volarly during motion, the proximal pin is not in the true axis of rotation and must be repositioned.

Technique 5: Hemi-Hamate Autograft

Step 1: Preparation of the Defect

Expose the PIP joint via a volar approach. Excise the comminuted volar fragments to create a clean, geometric rectangular defect at the volar base of the middle phalanx. Measure the dimensions of the defect (width, depth, and articular arc).

Step 2: Harvest the Graft

Make a longitudinal incision over the 4th and 5th carpometacarpal joints. Expose the distal articular surface of the hamate.

• Identify the ridge between the 4th and 5th metacarpal facets. This ridge matches the median ridge of the middle phalanx base.
• Using an oscillating saw and osteotomes, harvest a graft matching the exact dimensions of the PIP defect.

Step 3: Fixation

Transfer the graft to the PIP joint. It should fit snugly into the prepared defect.

• Fix the graft with two or three 1.0 mm or 1.2 mm lag screws. Ensure the articular surface is perfectly flush with the native dorsal cartilage of the middle phalanx.
• Confirm concentric reduction and stable fixation under fluoroscopy.

Post-Operative Protocol

Phase 1: Early Motion (Days 1-21)

• Dorsal Block Splinting / Extension Block Pinning: The patient is placed in a dorsal blocking splint (usually 20 to 30 degrees of flexion). Active flexion and extension within the limits of the splint or pin are encouraged immediately. Therapy supervision is highly recommended.
• Dynamic Fixator: Active motion is encouraged immediately to mould the healing articular surface and prevent adhesions. The traction maintains joint space during motion.
• ORIF / Hemi-Hamate Graft: If fixation is absolutely stable, early protected motion in a dorsal blocking splint is initiated.
• Eaton Arthroplasty: The joint is immobilised with a transarticular K-wire for 2 to 3 weeks to protect the volar plate advancement from stretching.

Phase 2: Splint Weaning (Weeks 3-6)

• K-wires (extension block or transarticular) are removed in the clinic at 3 to 4 weeks.
• The dorsal blocking splint is gradually straightened (10 degrees per week) or discontinued to allow terminal extension.
• Focus transitions to regaining full extension while maintaining the flexion arc. Buddy taping is often used for protection during activities.

Phase 3: Strengthening (Weeks 6-12)

• Formal strengthening exercises begin after clinical and radiographic evidence of union (usually 6 to 8 weeks).
• Dynamic extension splinting (e.g., Capener splint) may be initiated if a flexion contracture persists.

Special Case: Chronic Fracture-Dislocations

• Definition: Injuries presenting after 3 to 4 weeks.
• Pathology: The fracture has often malunited, the volar plate is heavily scarred, the collateral ligaments are contracted, and the articular cartilage may be damaged from chronic subluxation.
• Management: Closed reduction is impossible. ORIF is technically extremely demanding and often fails due to callus, bone resorption, and cartilage damage.
• Preferred Options: Volar plate arthroplasty (Eaton) is highly effective for chronic cases, providing a fresh, smooth gliding surface. For very large defects in young patients, a hemi-hamate autograft can reconstruct the articular contour and provide hyaline cartilage.
• Prognosis: Worse than acute injuries. Patients must be explicitly counselled to expect a permanent loss of motion (often 20 to 30 degrees of terminal extension) and a permanently swollen, thickened joint. The goal is a painless, stable arc of motion, not a normal finger.