Albert Leung and Philip E. Blazar
DEFINITION
Volar plate arthroplasty (VPA) provides a volar restraint to dorsal subluxation and dislocation of either the middle or distal phalanx base to maintain reduction of the proximal interphalangeal (PIP) or distal interphalangeal (DIP) joint. It resurfaces the volar portion of the injured joint using local tissue (volar plate).
VPA is used much more commonly for PIP joint stability than DIP joint stability.
ANATOMY
The volar plate, which is the primary restraint against hyperextension instability, lies palmar to both the PIP and DIP joints, separating the joint from the flexor tendon(s).
At its origin, the volar plate is “swallowtail” shaped and connected only by proximal checkrein ligaments to the phalanx and fiberosseous tendon sheath (FIG 1A).
Distally, the VP is primarily cartilaginous. It inserts centrally via the periosteum and laterally with a conjoined insertion through the collateral ligaments (FIG 1B).
The volar plate glides proximally and distally with joint motion.
The collateral ligaments originate on the dorsal radial and dorsal ulnar surfaces proximal to the joint. The proper collateral ligaments insert on the volar radial and volar ulnar surface distal to the joint, and the accessory collateral ligaments insert into the lateral margin of the volar plate, creating a box-type configuration (see FIG 1B).
In subacute or chronic cases of dorsal joint subluxation or dislocation, these ligaments contract, thereby accentuating the deformity by virtue of their oblique orientation.
The flexor digitorum superficialis (FDS) inserts just distal to the volar plate on the middle phalanx.
Due to the direction of pull, forces exerted by the FDS may accentuate dorsal subluxation of the middle phalanx base when the volar restraints are lost.
PATHOGENESIS
Injuries to the PIP and DIP are caused by longitudinal compression or hyperextension forces (common in sports injuries) and typically occur in young, active individuals.
Dorsal fracture dislocations of the PIP occur with damage to the volar articular surface of the middle phalanx when a force drives it dorsally against the condyles of the proximal phalanx.
Chronic subluxation or dislocation (more than 6 weeks) often occurs, especially with the PIP joint when the injury is perceived as minor and is considered a “sprain.”
NATURAL HISTORY
Chronic subluxation of the PIP joint leads to poor function and degenerative arthritis.
Flexion of the joint is limited and painful.
Despite optimal surgical treatment, PIP joint fracturedislocations often result in some loss of PIP or DIP joint motion.
PIP joint injuries, even those that do not require surgical treatment, commonly result in a protracted period of symptoms (eg, swelling, stiffness, pain) beyond what patients expect from a “minor” injury.
PATIENT HISTORY AND PHYSICAL FINDINGS
When taking the patient’s history, ask about the mechanism of injury, time since injury, any prior injuries, and the direction of deformity. Time since injury and mechanism of injury help determine the most appropriate treatment for any particular PIP joint injury.
FIG 1 • A. Volar view of the PIP joint. The PIP joint is supported by ligamentous structures that include the collateral ligaments on each side, with the volar plate and flexor tendons underneath. B. Sagittal view of the PIP joint showing the relative positions of the central slip, volar plate, collateral ligaments, and accessory collateral ligaments.
Inspect the finger for any swelling or deformity. Clinical deformity may be subtle, even with significant subluxation.
Examine range of motion, noting degrees of PIP motion. With joint subluxation, patients will have painful and limited flexion.
Examine joint stability; joints that are dislocatable will need intervention for stability (eg, extension block splinting, VPA).
IMAGING AND OTHER DIAGNOSTIC STUDIES
Every patient with a PIP injury must have anteroposterior, lateral, and oblique radiographs to evaluate for a PIP joint fracture or subluxation (FIG 2A).
The severity of the fracture and degree of involvement of the middle phalanx often are much greater than they appear on these radiographs.
In evaluating for a subluxation by radiographs, a true lateral view of the PIP joint is mandatory. A dorsal V sign at the joint indicates that the articular surfaces are neither congruent nor parallel (FIG 2B).
Fluoroscopy allows dynamic evaluation of the joint and its stability and often is also the best way to obtain magnified images and a perfect lateral view.
CT scans rarely are needed but can effectively evaluate the articular surfaces and define the bone loss.
DIFFERENTIAL DIAGNOSIS
Acute central slip injury (ie, boutonniere deformity)
PIP joint fracture
PIP dislocation
Volar plate or collateral ligament sprain without instability
FIG 2 • A. Lateral radiograph of subluxation of the PIP joint. B. PIP joint subluxations typically display a signature dorsal V sign on the lateral radiograph, as described by Light.6
NONOPERATIVE MANAGEMENT
Closed reduction and extension block splinting are appropriate for PIP fracture subluxations when a stable concentric joint reduction is obtained and maintained in an acceptable position.
If more than 65 degrees of flexion is required to maintain reduction, surgical reconstruction should be strongly considered.
Articular defects will often dramatically remodel in a concentrically reduced, mobilized joint.
SURGICAL MANAGEMENT
For simplicity, the techniques here describe VPA for the PIP joint, but the same principles may apply to the DIP joint. The primary difference is that the FDP insertion on the volar base of the distal phalanx makes exposure of the volar plate more complicated.
Indications
Acute fracture-dislocations that are unstable after closed reduction of the PIP joint in cases in which the volar base of the middle phalanx is not reconstructable, or if surgical reconstruction is less likely to achieve a functional result
Chronic subluxations or dislocations up to 2 years following trauma
A normal articular contour of the proximal phalanx is a prerequisite.
An intact dorsal cortex and dorsal articular surface are required.
Some authors (eg, Burton4) use VPA for chronic osteoarthritis in select situations.
Preoperative Planning
Fractures typically involve over 30% of the surface of the middle phalanx base, and the joint is subluxated or dislocated. If the fracture involves under 30% of the joint surface, it typically can be managed either in a closed manner or with less invasive techniques for the acute scenario.
The literature is unclear whether a specific degree of involvement of the articular surface precludes VPA (ie, is too large), but involvement of the dorsal cortex is a contraindication.
VPA is a less successful treatment for injuries involving over 50% to 60% of the middle phalanx articular surface. In these cases, recurrent subluxation is common.
In chronic dislocations, soft tissue contracture and heterotopic bone may make dissection and relocation more complex.
Positioning
The patient is positioned supine on the operating table with the affected arm on a hand table.
Intraoperative fluoroscopy is critical to this procedure, and it is important to position the hand relative to the fluoroscopy unit so that a true lateral view of the injured PIP joint may easily be obtained.
The surgery is performed under tourniquet control.
TECHNIQUES
PRIMARY INCISIONS AND EXCISIONS ON THE VOLAR SIDE
The joint is exposed using two limbs of a Bruner incision centered at the PIP flexion crease, elevating a radially based flap (TECH FIG 1A).
The radial and ulnar neurovascular bundles are identified and mobilized throughout the field to prevent a traction injury when the PIP joint is hyperextended to achieve optimal visualization (TECH FIG 1B).
The flexor sheath is incised as a rectangular flap between the A2 and A4 pulleys and protected for later repair.
The flexor tendons are atraumatically retracted radially or ulnarly, as needed to visualize the volar plate (TECH FIG 1C,D).
TECH FIG 1 • A. The Bruner incision is centered over the PIP flexion crease, with the vertex on the ulnar side. B. To prevent traction injuries, mobilization of the neurovascular bundles is necessary. C.Illustration of retraction of the flexor tendons and neurovascular bundles relative to the volar plate. D. The flexor tendons must be retracted radially and ulnarly to access the volar plate. The proposed incision to detach and mobilize the volar plate is outlined in pen.
DETACHMENT OF THE VOLAR PLATE
The volar plate is detached from the middle phalanx or fracture fragments, including as much tissue as possible.
The volar plate is incised from the proper and accessory collateral ligaments through an incision along its radialand ulnar-most margins (Tech Fig 1D).
The volar plate flap must be as long and broad as possible to maintain adequate stability of the arthroplasty. It should be symmetrical radially and ulnarly to avoid angular deformities.
The collateral ligaments are excised.
The joint is then hyperextended approximately 180 degrees (“shotgunning”) to achieve maximum visualization of the base of the middle phalanx (TECH FIG 2).
Small fragments of depressed articular cartilage or subchondral bone are débrided and saved for possible later use.
Care is taken to avoid over-resection and loss of the dorsal articular support.
TECH FIG 2 • Shotgunning. Hyperextending the joint allows clear visualization of the volar plate to the left, the avulsed bone, and the articular surface of each phalanx. The trough is fashioned symmetrically in the coronal plane, at the dorsalmost aspect of the articular defect to the right.
SHAPING THE ARTICULAR SURFACE OF THE MIDDLE PHALANX
A transverse trough is fashioned with an osteotome or a rongeur across the middle phalanx and finished with a small curette, at the juncture between the intact articular surface and the fracture defect (TECH FIG 2).
This trough must be symmetric in the coronal plane to avoid angular deformity. The depth of the trough at its dorsal side should be the thickness of the volar plate, thereby allowing a smooth transition from articular cartilage to transposed volar plate.
TRANSPOSING THE VOLAR PLATE
A 3-0 nonabsorbable grasping suture (eg, Bunnell fashion) is placed in both the ulnarand radial-most margins of the volar plate flap (TECH FIG 3A).
Two straight Keith needles are passed through each side of the base of the middle phalanx using a wire driver. They are placed as far radially, ulnarly, and distally in the bone defect as possible, and directed centrally to penetrate the cortex distal to the central slip insertion (TECH FIG 3B).
The sutures are tensioned as the middle phalanx is flexed, bringing the volar plate into the defect at a level that produces a smooth transition from the intact dorsal base of the middle phalanx to the volar plate.
The joint should remain flexed about 20 to 25 degrees so the volar plate can advance both distally and dorsally.
Examine the reduction with a true lateral fluoroscopic view on a mini C-arm (TECH FIG 3C).
The base of the middle phalanx should glide over the head of the proximal phalanx and should not hinge open dorsally.
The fingertip should be able to touch the distal palmar crease (110 degrees of flexion).
If the PIP joint lacks substantial extension or has inadequate flexion, it may be necessary to advance the volar plate distally by teasing the checkrein ligaments from their origin or by fractional lengthening through stepcutting (TECH FIG 3A).
TECH FIG 3 • A. Suturing the volar plate. Sutures are passed through the margins of the volar plate and through the base of the middle phalanx using straight Keith needles. The volar plate is advanced into the trough, resurfacing the PIP joint. It may be necessary to advance the volar plate by step-cut lengthening of the checkrein ligaments. B. Bone resection. This diagram shows the needle holes in relation to the resected bone, the collateral ligament stubs, and the extensor mechanism central tendon. The holes in the middle phalanx should be as far dorsal and lateral as possible for maximum stability. C. The PIP joint has now been reduced and stabilized as shown.
SECURING THE VOLAR PLATE
The sutures may be tied over a button dorsally.
Alternatively, the sutures may be tied directly onto periosteum via a small incision distal to the central slip insertion. Care must be taken to ensure the sutures do not entrap the lateral bands or injure the central slip.
In the acute setting, fractured bone fragments collected during the volar plate detachment may be placed in the defect of the middle phalanx, distal to the advanced volar plate. This provides support to the base of the phalanx.
A K-wire is used with the joint in slight flexion to maintain reduction for 3 weeks (TECH FIG 4).
Alternatively, the joint reduction can be maintained with an articulated external fixator to allow for early motion.
TECH FIG 4 • Lateral diagram of VPA. The overall diagram of this procedure illustrates the joint with a double-ended Kwire for stability and the volar plate secured by sutures.
POSTOPERATIVE CARE
The K-wire PIP joint fixation is removed at 2 to 3 weeks, when active flexion and extension are begun.
An extension block splint is used during weeks 3 to 6 after the operation.
Motion of the DIP is encouraged before K-wire removal, because deficits in DIP motion have been reported after VPA.
After 6 weeks, the pullout suture, if one was used, is removed.
A dynamic extension splint may be used at 6 weeks if the achieved extension is not as expected based on intraoperative range of motion.
OUTCOMES
More normal PIP motion is restored in acute injuries than in chronic injuries: 85 degrees of active PIP motion versus 60 degrees.
Patients can expect to see continued improvement in range of motion up to 1 year after VPA.
Mild contractures of the DIP joint (10 to 20 degrees) are common. Patients are encouraged in DIP motion during rehabilitation.
COMPLICATIONS
Resubluxation or dislocation
Flexion contracture of the PIP or DIP joint
Angular deformities
Pin and wire track infections
Pain
Stiffness
Degenerative arthrosis
REFERENCES
1. Blazar PE, Robbe R, Lawton JN. Treatment of dorsal fracture/ dislocations of the proximal interphalangeal joint by volar plate arthroplasty. Tech Hand Up Extrem Surg 2001;5:148–152.
2. Blazar PE, Steinberg DR. Fractures of the proximal interphalangeal joint. J Am Acad Orthop Surg 2000;8:383–390.
3. Bowers WH, Wolf JW, Nehil JL, et al. The proximal interphalangeal joint volar plate. I. An anatomical and biomechanical study. J Hand Surg Am 1980;5:79–88.
4. Burton RI, Campolattaro RM, Ronchetti PJ. Volar plate arthroplasty for osteoarthritis of the proximal interphalangeal joint: a preliminary report. J Hand Surg Am 2002;27:1065–1072.
5. Eaton RG, Malerich MM. Volar plate arthroplasty of the proximal interphalangeal joint: a review of ten years’ experience. J Hand Surg Am 1980;5:260–268.
6. Light TR. Buttress pinning techniques. Orthop Rev 1981;10:49–55.
7. Malerich MM, Eaton RG. The volar plate reconstruction for fracture-dislocation of the proximal interphalangeal joint. Hand Clin 1994;10:251–260.
8. Rettig ME, Dassa G, Raskin KB. Volar plate arthroplasty of the distal interphalangeal joint. J Hand Surg Am 2001;26:940–944.