➢ Early recognition and treatment of interphalangeal joint fracture-dislocations are important for good outcomes.
➢ Reduction of the joint without subluxation is more important than anatomic reduction of the fracture fragments.
➢ Flexion contractures and stiffness are common. Obtaining full range of motion is rare and early motion is a key treatment element for success.
➢ Open treatment is indicated if closed measures fail and recurrent subluxation or dislocation occurs.
The proximal interphalangeal joint is a commonly injured joint in the hand. Fracture-dislocations can be devastating injuries if missed or improperly treated1,2. This joint is more susceptible to injury because of its long lever arm and the high congruity of the articular surfaces1,3. It has a large arc of motion, around 120°. Stiffness and pain are common sequelae and can occur in spite of diligent treatment.
Because of the asymmetry of the proximal phalangeal condyles, there is slight supination as the proximal interphalangeal joint flexes4. The joint is stabilized by the osseous architecture as well as the volar plate and collateral ligaments. The volar plate attaches to the proximal phalanx through the check ligaments and distally to the base of the middle phalanx. It is thinner centrally and blends with the collateral ligaments laterally5. It functions to prevent hyperextension and glides proximally with joint flexion5. Coronal plane stability is provided by the accessory and proper collateral ligaments6.
The proximal interphalangeal joint most commonly dislocates dorsally and the volar side of the middle phalanx is usually fractured. The volar plate can avulse with varying amounts of bone from the volar lip. These are usually not comminuted fractures compared with an injury that involves an axial load with the joint in flexion7,8. The action of the volar plate is disrupted and the buttress effect of the volar lip of the middle phalanx is lost.
With a volar fracture-dislocation, the middle phalanx translates volarly and the fracture occurs at the dorsal base. With hyperflexion of the proximal interphalangeal joint, the central slip may fail because of either rupture or osseous avulsion of the dorsal lip of the middle phalanx7. When the finger is in extension with an axial load, the articular surface sustains an impaction or shear force that causes dorsal lip fractures of the middle phalanx. The flexor digitorum superficialis is unopposed by the avulsed central slip and the middle phalanx subluxates volarly9.
In a crush or axial load-type injury, contiguous surfaces can be injured in a pilon-type fracture10.
Fracture-dislocations of the proximal interphalangeal joint are classified on the basis of direction and stability1. Clinically, a stable joint is one that can maintain reduction; this is determined on radiographs and through functional evaluation11,12. Stability is determined by the percentage of articular surface that has fractured9,13. Fractures that involve <30% of the joint surface are typically stable, fractures that involve 30% to 50% of the joint surface are considered tenuous, and fractures that involve >50% are often unstable1,14. Tyser et al.15 performed a biomechanical study on eighteen joints showing no proximal interphalangeal subluxation with a 20% volar osseous defect (zero of eighteen joints) and all specimens subluxating with a 60% defect (twelve of twelve joints) at a mean flexion angle of 67°. In the specimens with a 40% defect, 28% (five of eighteen joints) subluxated at a mean flexion angle of 14°. Increasing flexion will increase the stability of dorsal fracture-dislocations, but increased instability is seen when >30° of flexion is required16.
Volar fracture-dislocations are usually stable in full extension with nondisplaced fractures up to 50% of the dorsal surface7. Pilon injuries involving the entire articular surface are considered unstable injuries10.
Anteroposterior and lateral radiographs of the affected finger are the standard imaging modalities along with radiographs of the entire hand to rule out any associated injuries. A computed tomographic (CT) scan is usually unnecessary unless better visualization of a depressed articular fracture is needed.
Evaluating the fracture on the anteroposterior radiographs may show radial or ulnar subluxation of the joint or one-sided fracture involvement. The lateral radiograph will show joint subluxation and whether the volar or dorsal surface is involved in the fracture. It will also be the view in which the physician will evaluate the percentage of the joint surface that is fractured. A subtle V sign may be seen dorsally; this is a V-shaped space created at the dorsal joint surface that signifies a non-concentrically reduced joint17 (Fig. 1).
Important patient factors include age, hand dominance, work function, activity level, and medical comorbidities. The mechanism of injury, time since injury, previous treatment, soft-tissue swelling, and the nature of the fracture of the middle phalanx are injury characteristics. The goal of treatment is to create a stable and congruent joint. The treatment modality selected must allow early protected movement through a stable range of motion if possible2. A concentrically reduced and aligned joint is critical for good clinical outcomes7,13. The accuracy of the reduction of the base of the middle phalanx fracture has not been shown to correspond to clinical outcomes, and small articular step-offs are tolerated as long as the joint is reduced18,19. Early range of motion of the digit will promote cartilage healing and helps to mold comminuted fragments of a pilon fracture into a congruent surface20.
The initial treatment of the dislocated proximal interphalangeal joint is to try to obtain a concentric reduction. This can be accomplished with a digital block and reduction maneuver of distraction followed by flexion for a dorsal dislocation and extension for a volar dislocation. It is important to evaluate stability both actively and passively once reduced. The collateral ligaments are tested with radial and ulnar-directed forces, and attempted dorsal translation and hyperextension evaluate the competency of the volar plate5. The central slip should also be tested through an Elson test, especially in volar fracture-dislocations21.
Post-reduction radiographs should be taken to evaluate for joint congruency. Flexion and extension radiographs can be obtained to evaluate hinging of the joint, which cannot be ensured from physical examination alone14.
Stable proximal interphalangeal joint fracture-dislocations that maintain reduction through the normal range of motion can be treated nonsurgically with buddy taping to prevent hyperextension. Early motion has been shown to be superior to immobilization22,23. If the finger is unstable near full extension, the injury can be managed with extension block splinting that prevents full extension into an unstable range but allows flexion1. Weekly splint modifications to allow more extension and radiographs are key to ensure continued stability1,3. Although acceptable outcomes with as much as 60° of extension block have been reported, most authors agree that when the finger requires >30° of flexion, surgical treatment should be considered to prevent a boutonniere deformity7,16,22. Hamer and Quinton24 found approximately 70% good results with extension block splinting, and poor results were seen in patients who had joint subluxations in their splint.
For volar injuries, the central slip must be allowed to heal. This involves immobilization of the proximal interphalangeal joint with a dorsal extension splint for three to four weeks with motion allowed at the distal interphalangeal and metacarpophalangeal joints.
Dynamic extension splinting with a Capener splint or similar device is used for two weeks following initial immobilization to allow for active flexion while protecting the central slip7.
Surgical treatment is appropriate for fracture-dislocations that cannot be reduced or that cannot maintain congruent reduction. Closed techniques avoid soft-tissue trauma with less resultant swelling and stiffness.
Closed Reduction and Percutaneous Stabilization
Percutaneous fixation includes transarticular pinning through the proximal interphalangeal joint to hold the reduction temporarily until the soft-tissue stabilizers and the osseous fragments heal. Usually the joint is stable and pinned at 30° of flexion and is held for four weeks before the pin is removed in the outpatient setting and proximal interphalangeal motion is begun. This technique is quick and does not involve soft-tissue disruption, but it can lead to stiffness and flexion contracture.
Newington et al.25 treated eleven dorsal fracture-dislocations with transarticular pinning with a mean follow-up of sixteen years. They reported a mean fixed flexion deformity of 8° and a mean motion arc of 85°.
Extension-Block Pinning for Dorsal Fracture-Dislocations
An extension-block pin can be used to hold a joint reduced in flexion. This avoids bulky splints that must include others fingers and the wrist to stay in place. A longitudinal pin is placed dorsally through the head of the proximal phalanx to block the joint from extending into an unstable position26 (Fig. 2). Flexion of the proximal interphalangeal joint is allowed to begin immediately and the wire is removed at three weeks. It does require a cooperative patient and has a higher infection rate at the pin site due to development of a synovial fistula.
Waris and Alanen27 reviewed thirteen patients with an impacted fracture of the volar base of the middle phalanx of >40% with a mean follow-up of five years. The authors used an extension-block pin and a percutaneous 2.0-mm cortical hole laterally to disimpact the depressed fragments using a small Kirschner wire. There was a mean 3° flexion contracture with 86° of active flexion. Tip pinch was equal to the other side, grip strength was 3 kg less, and nine of the thirteen patients reported no pain. Six final radiographs showed narrowing of joint space and mild degenerative changes. Maalla et al.28 reviewed twenty-two patients with follow-up of more than 2.5 years who were treated with extension-block pinning and reported a motion arc of >85° and 82% good results.
External Fixation and Dynamic Traction
Ligamentotaxis is achieved by traction through external fixation and holds the joint reduced and distracted and is useful for comminuted fracture-dislocations in which the joint can be reduced and can be held with traction. Although commercially available frames can be used, in most instances, a frame constructed from Kirschner wires with or without rubber bands will suffice. Distraction is achieved by either bending one wire against the other or creating a force coupled with a rubber band29. The simplest frame is created with the use of two 1.2-mm Kirschner wires and includes a stable wire in the proximal phalanx and a moving wire in the middle phalanx30. The patient mobilizes immediately through the limited range allowed by the frame with frequent radiographs made to ensure a maintained reduction. Ellis et al.31 treated eight patients using a technique described by Slade et al.32. They found an 89° arc of motion and a grip strength of 92% of the opposite side. Similar results were seen in thirty-four patients, all of whom returned to prior activity levels with a mean proximal interphalangeal joint motion arc of 88°. Twenty-four percent of patients had superficial pin-site infections treated with oral antibiotics33.
Closed Reduction and Pinning of the Fracture
Although most closed techniques focus on reduction of the joint, some authors have attempted to reduce and to fix the middle phalangeal fracture percutaneously as part of the treatment. Vitale et al.34 used a combined technique of closed reduction and percutaneous pinning of the fracture with dorsal block pinning for fracture-dislocations involving at least 40% of the articular surface. The investigators reported a mean range from 4° to 93° at the proximal interphalangeal joint and maintenance of reduction with healing of fractures.
Open Treatment of Dorsal Fracture-Dislocations
An open reduction is required when closed techniques fail to achieve congruent joint alignment. The aim of open reduction is to allow early motion without transarticular fixation. Manipulation and fixation of small fragments are technically challenging and the approach to these fragments does add soft-tissue insult. Volar and lateral approaches are employed for reduction and fixation.
Indications for an open volar approach with internal fixation are an unstable dorsal dislocation with a large volar fragment, late presentation, and failed reduction.
Indications for an open lateral approach with internal fixation are lateral fracture-dislocations and dorsal and volar fragments (Fig. 3). Lee et al.35 used a midlateral incision to repair the volar plate in fractures involving small osseous fragments using suture fixation and showed retained reduction with an arc of 92°.
Open reduction and internal fixation can be accomplished with plates and screws, screws alone, or Kirschner wires and is usually more suited for larger fragments that can hold fixation. Typical screw diameters range from 1 to 2.4 mm, diameters of Kirschner wires range from 0.9 to 1.2 mm, and plates can be mini-fragment bone specific or generic and conformed to the bone. A zigzag incision is made over the volar aspect of the proximal interphalangeal joint and is taken down to the level of the flexor tendon. As described by Hamilton et al.36, the sheath is incised between the A2 and A4 pulley so that the flexor tendons can be moved out of the way. The volar plate is detached distally and is reflected proximally with the attached fracture fragment or fragments (Fig. 4). The centrally depressed articular fragments of the base of the middle phalanx are reduced and the volar plate with attached fragments is anatomically restored and is stabilized with a temporary wire. A buttress plate, or screws alone, is applied to the volar aspect of the middle phalanx and stability of the reduction is assessed36 (Fig. 5 and Fig. 6). The incised tendon sheath may be interposed between the tendons and the plate if there is concern regarding tendon adhesions to the plate.
A more extensive approach is employed if direct visualization of the base of the middle phalanx is required. The collateral ligaments are serially released off the base of the middle phalanx and the digit is increasingly hyperextended until it can be hinged fully open, with adjacent articular surfaces of the proximal interphalangeal joint lying together. Smaller fragments can be captured with a lasso of malleable steel wire, and larger fragments can be fixed with screws placed in a lag fashion. Formal collateral repair is not required and the volar plate can be loosely reapproximated to the accessory collateral ligaments on either side.
Wolfe and Katz37 reported on six patients treated with open reduction and Kirschner wire and tension band, mini-screw, or volar plate arthroplasty and found 100% maintenance of reduction and patient satisfaction.
Hamilton et al.36 retrospectively reviewed the cases of nine patients who underwent fixation with mini-screws for dorsal fracture-dislocations with a mean forty-two-month follow-up. The fractures averaged 56% of the articular surface, and six patients had three or more volar fragments, one patient had two volar fragments, and two patients had one volar fragment each. The mean motion arc was 70° with a flexion contracture of 14°. Decreased postoperative motion and increased complications were seen with more than one fracture fragment. The mean grip strength at the time of the latest follow-up was 98% of the contralateral side.
Cheah et al.38 reviewed the cases of thirteen patients stabilized with a mini-plate and screws with a mean follow-up of twenty-five months. They found a mean QuickDASH (an abbreviated version of the Disabilities of the Arm, Shoulder and Hand questionnaire)39 score of 4, but three patients had a subsequent surgical procedure to improve motion (implant removal and flexor tenolysis) and one patient requested the removal of an asymptomatic implant. Grip strength was 85% of the opposite side with a mean proximal interphalangeal joint motion of 75°. Twelve patients achieved fracture union with maintenance of reduction. Three patients had narrowed joint space and mild degenerative changes.
Ikeda et al.40 reported on results using a mini-plate for fracture fixation involving >40% of the articular surface in eighteen patients with 100% osseous union, no recurrent subluxation, and a mean arc of motion of 85%. Two patients had decreased distal interphalangeal motion as a result of tendon adhesion with a longer plate that was not used in subsequent patients. Komura et al.41 reported ranges of motion of 0° to 100° for the proximal interphalangeal joint and 0° to 80° for the distal interphalangeal joint after use of a mini hook plate for fixation.
Volar Plate Arthroplasty
The concept behind the volar plate arthroplasty is to recreate the volar buttress that is lost from the fracture at the base of the middle phalanx in a dorsal fracture-dislocation. With the adoption of hemi-hamate arthroplasty, volar plate arthroplasty is rarely indicated for posttraumatic proximal interphalangeal joint problems. The volar plate arthroplasty is performed through the same approach as discussed for open reduction. The volar plate is identified and is mobilized separately from the collateral ligaments and then is advanced into the articular defect using sutures, anchors, or pullout wires. The construct can be protected with a transarticular or extension-block Kirschner wire. Although the pin protects the repair, a transarticular pin prohibits early motion. Using a dynamic external fixator to allow for early motion has been reported7,13. The long-term stability of the proximal interphalangeal joint following this procedure is questionable, especially when the fracture involves >50% of the joint surface42.
Eaton and Malerich43 reviewed the cases of twenty-four patients treated with volar plate arthroplasty and found that surgery within six weeks had a final motion of 95° compared with 78° after six weeks. Better results were reported in patients undergoing a surgical procedure within four weeks of their injury44. If the volar plate is unable to be reattached or is insufficient to hold the joint from subluxation, one or both slips of the flexor digitorum sublimis can be tenodesed as described by Catalano et al.45 to prevent hyperextension. Their results showed a mean range of motion of 2° to 83°, and ten of twelve patients had good to excellent results.
Developed by Hastings et al.46, the hemi-hamate arthroplasty was introduced as a way to recreate the volar buttress of the middle phalanx with bone transferred from the hamate. The contour of the distal hamate at the carpometacarpal joints of the ring and small fingers follows the cup-shaped geometry of the proximal middle phalanx. Fractures that cannot be addressed through open reduction and internal fixation because of comminution and those that require late reconstruction after failing external or internal fixation or volar plate arthroplasty are good candidates for this procedure, provided that cartilage on the proximal phalanx is preserved.
An extensile volar approach is performed. The fracture fragments are debrided and a smooth surface for acceptance of the graft is created. An oversized osteochondral graft is obtained from the dorsal lip of the hamate centered at its articulation with the fourth and fifth metacarpals. The graft is set into place and is reshaped to form a concave surface proximally to recreate the volar buttress. The graft is provisionally held with a small Kirschner wire and then is transfixed with at least two 1.0 or 1.3-mm screws (Fig. 7). The joint is reduced and alignment and articular congruity are assessed fluoroscopically. An osseous step-off may be visible under fluoroscopy because of the thicker articular cartilage of the hamate46.
Complications from this procedure are dorsal subluxation, if the volar buttress is not recreated, and hyperextension for failed volar plate repair. Radial or ulnar instability is seen if the graft width is not correct. A prominent implant at the dorsal part of the finger can be felt when swelling subsides if the screws are too long. Also, the graft can fail to heal to the middle phalanx, although this is rare47.
Postoperative care focuses on early motion and edema control. Usually a dorsal blocking splint (around 15°) allows for immediate active flexion. By three weeks, the patient is allowed to perform active assisted flexion with more aggressive stretching of any contractures at four to six weeks47.
Williams et al.48 reported on twelve patients with a mean 60% defect in the middle phalanx with a mean time to hemi-hamate arthroplasty of forty-five days. They reported a mean proximal interphalangeal motion of 85° and a grip strength of 80% at a mean follow-up of sixteen months. There was 100% osseous union, and two patients had recurrent dorsal subluxation.
Calfee et al.49 reviewed the cases of twenty-two patients with 50% joint surface involvement who underwent hemi-hamate arthroplasty with a mean follow-up time of 4.5 years. Fourteen had acute injuries (less than six weeks) and eight had chronic injuries (mean, thirty weeks from injury) and showed active proximal interphalangeal motion of 70° and contracture of 19° with 95% grip strength. There were an increased visual analog scale (VAS) score for pain ratings at 2.6 for chronic reconstructions compared with 1.4 for acute reconstructions and a higher score on the Disabilities of the Arm, Shoulder and Hand (DASH) questionnaire at 9 points for chronic reconstructions compared with 2 points for acute reconstructions. Otherwise, no differences were seen in motion or strength. Afendras et al.50 reported that two of eight patients developed severe radiographic arthritis after four years and one patient had debilitating pain.
Volar fracture-dislocations are rare injuries but the goal is the same as with dorsal fracture-dislocations: restoration of joint alignment51. Unstable injuries and those with fracture displacement should be addressed surgically with pinning, external fixation, or open reduction and internal fixation. Mobilization of these injured joints is delayed until healing of the central slip.
A transarticular pin can be used to hold the joint in extension to allow for fracture-healing; this is especially useful for comminuted fractures7. Closed reduction and pinning or open reduction and internal fixation can be used for displaced fractures with minimal comminution7,51. Rosenstadt et al.51 treated seven of nine patients with closed reduction and transarticular Kirschner wire placement; two of these patients, in whom the fracture did not reduce with just this maneuver, required an additional oblique dorsal to palmar Kirschner wire into the dorsal fragment. The remaining patients required open reduction and internal fixation using the same fixation method and one pullout wire. Six patients were pain-free and none had functional limitation with postoperative motion of 91°. Five had >10° extensor lag and one had hyperextension of 10°. The authors also treated four chronic injuries that all required open reduction and internal fixation, two of which necessitated fragment excision and repair of the extensor mechanism by reinsertion of the central slip. The chronic injuries had a mean range of motion of 70°; one patient developed a swan neck, and two of the four patients had extensor lag at the proximal interphalangeal joint. The group with acute injuries and the group with chronic injuries had about 90% grip strength compared with the contralateral side.
Most pilon injuries are unstable and should be treated surgically14. These injuries can be treated with dynamic external fixation and open reduction and internal fixation, with the goal of restoring the concavity of the articular surface (Fig. 8). The superiority of one method has not been shown10. Sarris et al.52 treated six patients with a combination of traction and limited open reduction and internal fixation with Kirschner wires to improve positioning of fragments or to repair the central tendon. These patients had a mean motion of 94°, and one patient had pain with activities of daily living. Mansha and Miranda53 treated twelve patients with closed reduction and dynamic external fixation with a range of 13° to 87° and a mean follow-up of sixteen weeks; there were no serious complications and high levels of patient satisfaction.
The most common complication is joint stiffness, usually seen as a flexion contracture. As described by Leibovic and Bowers, the proper collateral ligaments have equal tension in flexion and extension, but the accessory collateral ligaments are looser in flexion; therefore, immobilization in flexion will cause the accessory collateral ligaments to shorten after prolonged periods4. Flexor tendon adhesions from surgical procedures or immobilization and articular incongruity will also lead to loss of motion. Multiple authors have stressed the importance of early edema control and motion2,3. The distal interphalangeal joint can also develop stiffness from immobilization3. Treatment is usually nonsurgical with progressive splinting and intensive therapy. Reports have discussed release for refractory flexion contractures that include accessory collateral ligaments, the volar plate, proper collateral ligaments, and flexor tendon adhesions. This shifts the arc of motion into more extension rather than increasing the total arc54.
Swan neck deformity or proximal interphalangeal joint hyperextension can be seen as a consequence of volar plate incompetence. If supple, this condition can be treated conservatively with splinting or surgically with volar plate advancement or repair or flexor digitorum superficialis tenodesis45,55. If it becomes a fixed deformity, it may require an open release and/or arthrodesis3.
Joint instability and redislocation after the first attempt at nonsurgical or surgical treatment ranges from 0% to 31%, with volar plate arthroplasty having the highest rate3. This will require intervention, usually surgically, using another technique or salvage procedure such as arthrodesis or arthroplasty3.
Multiple studies have shown that results are improved when injuries are treated early, regardless of the treatment method43,44,51,56. Open reduction and internal fixation was evaluated by Grant et al.56, who showed that the final proximal interphalangeal range of motion was worse for patients whose treatment was delayed for more than four weeks (86°) compared with patients treated acutely within two weeks (100°).
To our knowledge, there have been no prospective comparison studies for surgical techniques. Flexion deformities and stiffness are common and obtaining full range of motion is rare. Delayed presentation and recurrent subluxation have a worse prognosis. Joint reduction without subluxation is more important than articular congruity.
It is important for the surgeon and the patient to have realistic expectations depending on the severity of the injury and the length of time until treatment. Joint reduction and early motion are the keys to obtaining a better result.
Source of Funding: There was no external funding for this study.
Investigation performed at the Department of Orthopaedic Surgery & Rehabilitation, Loyola University Medical Center, Maywood, Illinois
Disclosure: None of the authors received payments or services, either directly or indirectly (i.e., via his or her institution), from a third party in support of any aspect of this work. One or more of the authors, or his or her institution, has had a financial relationship, in the thirty-six months prior to submission of this work, with an entity in the biomedical arena that could be perceived to influence or have the potential to influence what is written in this work. No author has had any other relationships, or has engaged in any other activities, that could be perceived to influence or have the potential to influence what is written in this work. The complete Disclosures of Potential Conflicts of Interest submitted by authors are always provided with the online version of the article.
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