Surgical Treatment of Interphalangeal Joint Arthritis 

Arthrodesis has been the time-honored surgical choice for the degenerated proximal interphalangeal (PIP) joint. In the late 1950s, Brannon and Klein developed total joint arthroplasty for the PIP joint.^[1] Adrian Flatt then reported his experience with a metallic, hinged prosthesis for the rheumatoid arthritis of the PIP and metacarpophalangeal (MCP) joints.^[2] These devices routinely failed due to loosening or cortical breakout that was primarily caused by an artificially high center of rotation.

Numerous total joint devices have been introduced to reconstruct the PIP joint, but regardless of design, these devices typically fail due to difficulties in restoring the biomechanics of the joint. Swanson developed the silicone interpositional arthroplasty for the PIP joint.^[3] Although this device is a joint spacer and not a total joint replacement, pain relief has been predictable while durability has been suboptimal. The silicone PIP joint spacer remains the preferred choice for the prosthetic reconstruction of the PIP joint.^{[4, 5]}

Surface replacement arthroplasty (SRA) was developed as the first prosthetic device for the PIP joint that closely resembles the anatomic configuration of the phalangeal head and the articular base of the middle phalanx.^[6] Short-term results have indicated good function and durability. Current implant arthroplasty alternatives for the PIP joints are primitive; longevity and results will improve with better designs. As in other joints, anatomically and biomechanically sound restoration of the PIP joint with compatible materials will be the future goal of implant arthroplasty of the PIP joint.

The arthritic proximal interphalangeal (PIP) joint demonstrates fusiform joint swelling. With progression of the condition, marginal osteophytes (Bouchard nodes) become evident with progressive lateral deviation of the digits, as shown below.

During finger flexion, overlapping of the digits increases the functional impairment of the hand. Swan-neck and boutonniere deformities occur infrequently. Erosive osteoarthritis is an aggressive form of this condition that primarily affects the PIP and distal interphalangeal (DIP) joints in middle-aged women.^[7]

The proximal interphalangeal (PIP) joint is a ginglymus joint, or hinged joint, with a functional stability throughout its normal arc of flexion and extension. This bicondylar joint comprises a pair of concentric condyles that are separated by the intercondylar notch and allows a range of motion of 90-120°. The 2 corresponding articular surfaces of the middle phalanx are separated by a median ridge.

In contrast to the metacarpal articular head, the center of rotation of the phalangeal head remains constant throughout flexion and extension. This phalangeal joint configuration provides functional stability for lateral and rotatory forces. The oblique collateral ligaments arise from the dorsal and lateral aspect of each condyle to insert into the lateral tubercle, near the volar margin of the middle phalanx base. These collateral ligaments are 2-3 mm thick.

The volar plate consists of a distal portion of a thick fibrocartilaginous tissue that inserts into the volar lip of the middle phalanx base and is suspended by the transversely oriented accessory collateral ligaments. The proximal aspect of the volar plate is membranous and is attached to the neck of the proximal phalanx. The lateral portion of the volar plate thickens to form the volar check ligaments. See the volar view of a finger below.

Additional stability is provided to the interphalangeal joint by the extensor aponeurosis on the dorsal surface of the digit. The central slip of the extensor digitorum communis tendon attaches to the dorsal lip of the middle phalanx.

The oblique retinacular ligament arises from the side of the proximal phalanx and passes laterally into the PIP joint to join the lateral margin of the extensor band on the dorsal lateral aspect of the middle phalanx. The transverse retinacular ligament is superficial and runs dorsally from the volar surface of the capsule and flexor tendon sheath; it is attached to the lateral margin of the lateral tendon of the extensor mechanism. The Cleland ligament is dorsal to the neurovascular bundle, and the transverse Grayson ligament is volar to the neurovascular bundle, as shown below.

Indications and Contraindications for PIP Joint Surgery

Operative treatment is indicated for the proximal interphalangeal (PIP) joint when medical management has failed to relieve the pain, when the digit deformity is interfering with hand function, or when a significant restriction of motion limits the activities of daily living. When choosing the method of surgical treatment for a painful arthritic PIP joint, consider the clinical role of the PIP joint in the patient's particular activities.

Arthrodesis of the PIP joint is indicated mainly in the index and middle finger in a young or active patient or when a significant loss of bone has occurred.^{[8, 9, 10]} Arthrodesis should also be considered for anyone who is highly active on a regular basis.

Arthroplasty is indicated in less-active patients with painful, stiff, arthritic joints.^{[4, 6, 11]} Arthrodesis and implant arthroplasty of the PIP joint are contraindicated in the presence of recent or chronic infection or in infirm individuals who are unable to sustain the rigors of elective surgical intervention. Flatt noted that the PIP joint has the greatest degree of movement and functional adaptations of the hand.^[2] He found loss of movement to be a frequent complaint, especially in the third, fourth, and fifth digits.

Stability considerations are as important as motion considerations, especially in the radial digits that are involved during pinching activities. During pinching, the index finger must withstand forceful contact with the thumb, especially in the lateral or key pinch. Patients with impaired index fingers pinch with the middle finger when possible, so stability of the middle finger becomes more important when the index finger is also affected. Relatively few surgical options exist for the painful arthritic PIP joint. Most surgeries are arthroplasties or arthrodeses.

A Swanson interpositional arthroplasty of the proximal interphalangeal (PIP) joint through a dorsal approach has been recommended. However, the author has used a volar surgical approach that helps in the following ways:

• Minimizes the risk of extensor lag
• Avoids interference with the extensor tendons, preserving the central slip
• Allows for more prompt active range of motion in the postoperative period
• Eliminates the risk of central slip rupture with a resultant boutonniere deformity or a flexion contracture deformity

The volar approach also has better cosmetic and functional results. This approach provides an excellent exposure, which is critical given the importance of the technique with this type of procedure. However, with the volar approach, the risk of creating a swan-neck deformity exists.

A shortcoming of the Swanson implant is the sacrifice of the collateral ligaments, which makes implantation of the device in the index or long PIP undesirable. In contrast, the collateral ligaments are spared with implantation of most surface replacement arthroplasties (SRAs) of the PIP joint.

Many surgeons favor a dorsal approach, with longitudinal splitting of the extensor tendon or through a distally based flap of the central slip, as described by Chamay.^[12] The Chamay approach is the favored approach for SRAs.

Various nonsilicone implant arthroplasties are either available for use or under investigation. They include the Saffar, the Digitos, the DJO3A, the Mathy, and the Avanta PIP SRA.

In the volar arthroplasty approach (see below), a radial- or ulnar-based Bruner incision is made, with the apex at the PIP joint flexion crease. After the skin flap is elevated, the Grayson ligaments are completely released from their origin, exposing the neurovascular bundle. The bundle is then retracted, exposing the Cleland ligaments dorsally, which are also released.

The proximal and interphalangeal transverse digital arteries, which are consistently present as communicating branches from the digital arteries, are cauterized and transected, allowing full mobilization of the neurovascular structures.

The flexor tendon sheath is released by dividing the origin of the first and second cruciform pulleys and the third annular pulley at the volar plate. The volar plate is fully exposed and is released proximally and along its lateral margins from the accessory collateral ligaments, which are seen upon release of the transverse retinacular ligament from the volar capsule and tendon sheath.

The collateral ligaments are then released proximally, and the joint is opened by hyperextension, as shown below. The flexor tendons retract to one side, and the neurovascular bundles are displaced dorsally. Both articular surfaces are completely exposed in this manner. The medullary cavities of the bone are reamed in order to accommodate the proper size of the implant. See the images below. At this time, the authors use the recommended radiographic examination in order to assess adequate space and alignment of the digit. After the implant is inserted in place, it is essential that full range of motion exists and the implant is stable.

Resurfacing prosthetic procedures, with or without bone cement, have been designed for replacement of the PIP joint. Limited experience with this design has shown promise for future consideration as an alternative treatment. The exposure for most surface replacement arthroplasties spares the collateral ligaments; therefore, these joint replacements are an option for the index and long fingers.

An alternative treatment for proximal interphalangeal (PIP) joint osteoarthritis is arthrodesis of the joint in a functional position. Arthrodesis offers stability, durability, and little need for further procedures. This option is the procedure of choice for the index finger, which is usually subjected to lateral stress during pinching activities.

Arthrodesis is indicated mainly for the index and middle fingers in patients who are young or active or when a significant loss of bone has occurred, and this procedure continues to be the best surgical treatment for the painful, unstable PIP joint in the index or long finger. However, depending upon the patient's needs, arthrodesis may impair or even be incompatible with satisfactory function.

According to the American Medical Association's Guides to the Evaluation of Permanent Impairment, PIP arthrodesis is associated with a 50% impairment of the finger.^[13] On the ulnar aspect of the hand, preservation of mobility at the level of the PIP joint is important, especially to obtain the functional ability to grasp small objects.

The preferred position for arthrodesis of the PIP joints is 30-40° for the index and the middle finger, 50° for the ring finger, and 55° for the small finger.

Several different arthrodesis techniques for the PIP joint are based on the type of fixation that is used. The appropriate finger position varies for the radial to the ulnar fingers and with the assessment of the patient's particular needs. Kirschner wires (K-wires), interosseous wiring, tension band wiring, and screw fixation have been used to achieve a solid, nonpainful arthrodesis.^{[8] [9] [11]} The rate of nonunion is 0-10%.

Primary wound healing is the first goal of postoperative care. Elevation of the affected digit is important to prevent swelling. Active motion of the PIP joint usually begins on the third to seventh day, as the swelling subsides. A Coban elastic bandage helps to control swelling, as shown in the images below.

Following arthrodesis surgery, the PIP joint is protected in a dorsal and volar Orthoplast splint for approximately 4-6 weeks (see the image below). Motion of the MCP and DIP joints is allowed shortly after surgery. A hand therapist evaluates the patient to ensure adequate splinting, joint protection, and assistive devices to carry out the activities of daily living. (See the image below of a postoperative splint).

Swanson reported a need for revision of the silicone interposition arthroplasty in about 11% of digits.^[3] Implant fracture continues to be common, and recurrent ulnar deviation can also be present. Infection does not appear to be a problem with this type of prosthesis, and no infections have been recorded in any of the author's patients. In a follow-up study of 424 implants, Swanson et al reported a 5.19% rate of implant failure.^[11]

The rate of nonunions is 0-10% after arthrodesis. For Herbert screw fixation, the nonunion rate is 2%. Tension band wiring has been reported to have a 0% failure rate.

Patients with silicone implant arthroplasties are monitored indefinitely for signs of fracture. Patients who have undergone surface replacement arthroplasties are likewise monitored indefinitely for signs of loosening. Those who have undergone arthrodeses are monitored radiographically for signs of bony union. Hardware removal may become necessary, but this is not recommended until a year after surgery.

Both silicone implant arthroplasty and surface replacement arthroplasty (SRA) offer predictable motion and excellent pain relief for osteoarthritis of the PIP joint. More than 90% of arthroplasties achieve a functional arc of motion of more than 40° within 6-8 weeks after surgery. The best long-term results to date have been obtained with the silicone interposition arthroplasty.^[4]