Dislocations involving large volar fractures or those irreducible, unstable, or incongruous joints, regardless of fracture size, require operative intervention. In large disruptions of the middle phalanx volar surface, without the stabilizing collateral ligaments, the proximal phalangeal condyles sink into the volar plate and the distal inserting flexor digitorum superficialis (FDS) and flexor digitorum profundus (FDP) bend the middle phalanx rather than produce gliding palmar rotation of the articular base. The joint fails to remain congruent and parallel with the proximal phalangeal head through flexion. As a result, the joint hinges or angles. For these tenuous fractures, a transarticular Kirschner wire (K wire) may be placed through the PIP joint flexed at 40 degrees or more to diminish the subtle fracture articular site incongruities associated with eventual failure and EBS initiated after K-wire removal at 3 weeks. Failure of closed reduction leaves open intervention or constant traction as subsequent options. Open reduction with internal fixation and EBS mobilization at 3 weeks have been successful for tenuous fractures using such means as a single
K wire with or without a tension band, an interfragmentary screw or an interosseous wire with the well-known complications of malunion, pin tract infection, tenodesis, and posttraumatic arthritis. Other treatments include osteotomy with bone grafting, volar plate arthroplasty, secondary PIP arthroplasty, and arthrodesis.
For fracture-dislocations involving greater than 70% of the volar lip, neither advancing the volar plate nor neocollateralization will successfully maintain reduction. Only reconstruction of a competent volar buttress restraint will prevent redislocation. Yet attempts at realigning the large volar fragment by osteotomy and bone grafting usually fail, requiring PIP joint salvage through replacement arthroplasty or arthrodesis. In fact, regardless of the intervention(s), many ultimately end up with a pain-free ankylosis or require silicone arthroplasty.
For comminuted, impacted, and some irreducible fractures, treatment includes volar plate arthroplasty, dynamic force coupling devices, and transarticular K-wire placement. Secondary options include custom external fixation or placement of an interosseous wire through the volar plate to reduce the subluxed middle phalanx and mobilization with EBS. Typically the comminuted fragments are too small for fixation and are debrided.
In compound (open) dislocations involving a volar transverse tear in the skin with occasional protrusion of the head of proximal phalanx through skin and/or flexor tendon involvement, Stern and Lee found that the joint could not be stably reduced if the volar plate was not repaired distally, whereas Green and Posner found that it was not necessary with proximal tears.
Acutely treated injuries enjoy better outcomes than those that present late, that is, greater than 4 weeks after the injury. Injuries limited to volar plate avulsion with flexion deformity less than 30 degrees allow late primary repair, which may decrease the chance of severe flexion contractures.
For a subacute, greater than 10 days postincident, volar plate injury with collateral ligament injuries and persistent subluxation, restoration of range of motion may require excision of the contracted and normal primary and accessory collateral ligaments and dorsal capsule with immediate active range of motion, for excision of only the contracted ligaments will not restore full range of motion. Sparing part of the accessory collateral ligaments affords some stability.
Delayed treatment of large fractures requires release of the collateral ligaments to allow fragment reduction and possibly additional volar plate arthroplasty for comminuted fragments. Osteotomy of the proximal middle phalanx may provide an additional 40 degrees range of motion as the volar lip of the middle phalanx tilts to embrace the volar proximal phalanx.
For severe articular damage, failed reconstruction, persistent deformity, and pain, salvage procedures may be necessary. Arthrodesis in the radial digits to stabilize pinch, and replacement arthroplasty for the little and ring fingers to allow power grasp, may provide significant improvement in function and appearance.
Based on early range of motion within a stable arc, this straightforward, easily instituted and monitored method requires readily available and inexpensive materials and enjoys great success for stably reduced dislocations or as a means of protected range of motion after an open procedure. Although indicated for stable fractures of less than 10 to 15% involvement of the volar base, fractures constituting <40% of the base are still considered in the ideal group, and success has been found with some fractures as great as 70%. Once adequately reduced, a digital, hand, or forearm-based splint ensures that the digit remains well opposed to the splint and maintains flexion of the PIP joint blocked at 10 to 20 degrees greater than the point of demonstrable instability. Although McElfresh et al allowed up to 60 degrees of flexion to obtain stability, most accept a maximum of 30 degrees. This guideline prevents the chance of irreversible flexion contracture and delegates cases requiring greater than 30 degrees to other treatments. Lateral radiographs within the splint confirm this optimal point of flexion where the articular surfaces are absolutely congruent, for the PIP joint may become incongruous slowly, gradually, and subtly with extension. Some embark on immediate active range of motion, whereas others allow 1 week of rest. After 1 week of mobilization and radiographic and clinical confirmation of sustained congruity at rest and in maximum flexion, the degree of flexion is reduced by one third and the joint reassessed by a lateral radiograph. If radiographs demonstrate incongruity, extension is increased by only one half of the potential extension. After the usual interval to full extension (6-8 weeks), the splint is removed and grip and massage exercises are started, but pinch to the involved finger and stretching of the involved joint is avoided until grip strength is 50%. Full rehabilitation is complete by the third month postinjury.
Conversion to other forms of treatment is straightforward without delay in the overall process. Complications, such as flexion contractures are rare and salvageable. After the appropriate period of treatment has ended, for flexion contractures less than 10 degrees, a trial of active use equal to the period of splinting is usually sufficient and for contractures greater than 10 to 15 degrees, dynamic extension splinting is warranted.
Eaton and Malerich describe an elegant volar radial, rather than dorsal, approach to preserve the skin flaps should open reduction prove futile and be abandoned for a volar plate arthroplasty. After excising the sheath between the A2 and A4 pulleys, the volar plate is detached distally from the middle phalangeal fragments and laterally from the accessory collateral ligaments to open and shotgun the floor of the joint. Drilling a hole distal to the fracture allows introduction of a probe to elevate and reduce the fragments. Whichever method of fixation is used, the hardware should exit close to the central slip insertion without tenting the dorsal skin or penetrating the lateral bands or retinacular structures. Once the fracture is stabilized, extension block splinting may be instituted as above.
Volar Plate Arthroplasty (VPA)
Introduced by Eaton in 1967, VPA finds application in the following: acute fracture-dislocations displaying volar proximal middle phalangeal fractures of greater than 60% or those with excessive comminution and/or impaction; and chronic fracture-subluxation of the PIP, where there are degenerative changes or joint stiffness.
Utilizing the volar radial approach described above, the crucial step relies on creating a symmetric trough in the volar base of the middle phalanx to allow the volar plate to slip easily into the defect. Asymmetry usually prevents successful fracture reduction. Introducing a pullout wire Kessler style allows the ends to exit the distal corners of the volar plate and secure it to the radial and ulnar aspects of the middle phalanx through holes drilled laterally into the trough. The author (A.L.) employs tissue anchors, an updated version of this technique. Securing the wires to produce no more than 30 degrees of flexion reduces and stabilizes the joint, fills the volar defect, and decreases lateral angular deviation. By flexing the PIP and DIP joints while passing the pullout sutures dorsally, the lateral bands subluxate volarly, avoid entrapment, and thus lessen DIP stiffness. Embedded fragments of bone or cartilage can be left in place. A transarticular K wire is placed for joint stability and for very large disruptions (50—80%); an external fixator may be required for ~1 to 2 weeks. After K-wire removal at 2 weeks, EBS commences and the pullout wire is removed 1 week later, with unrestricted extension beginning at 4 weeks.
Complications include redislocation with an inadequately secured K wire, angular deformity with an undercorrected asymmetric trough or inadequate mediallateral reduction, and flexion contracture after 6 weeks with immobilization in excessive flexion or inadequate collateral ligament release.
Aside from acutely reducing the dislocated joint, VPA maintains congruous PIP joint reduction by providing a volar restraint, resurfaces the damaged articular surface of the middle phalanx with compatible vascularized material, fibrocartilage, and may be responsible for later joint remodeling and continuously improving range of motion even years later.
Robertson et al corrected the zigzag deformity by placing K wires to apply traction dorsally on the distal proximal phalanx and volarly on the proximal middle phalanx to realign the joint and axially on the distal middle phalanx to counteract flexor and extensor pull. Beasley used a static, bulky device incorporating distal traction with a volar splint to push the distal proximal phalanx dorsally. By decreasing the size of the device and allowing movement during traction, Agee enjoyed better results compared with Robertson et al and equaled those of McElfresh et al for acute fracture-dislocations and chronic fracture-dislocations.
Implementation requires an adequate stable dorsal shelf of proximal middle phalangeal bone and careful K-wire placement (Fig. 47—2). The K wire placed transversely in the proximal middle phalanx must be a safe distance away from the fracture and volar to the lateral bands. The K wire oriented perpendicular to the middle phalanx should not be driven too far distally through the lateral bands, preventing motion of the distal phalanx, or too deeply through the profundus tendon. Lastly, the transverse K wire through the proximal phalanx must be exactly through the axis of rotation to prevent hyperextension and possible
swan neck deformity. Often subacute unstable cases greater than 10 days postinjury cannot be reduced in a closed fashion, and require release of the malposi-tioned collateral ligaments.
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