Peter M. Murray and Christopher R. Goll
DEFINITION
Rheumatoid arthritis is a disorder that can affect the hands and can cause fatigue, muscle pain, loss of appetite, depression, weight loss, anemia, and immunocompromise. The effect on the hands is a combination of tenosynovitis and inflammation of the metacarpophalangeal (MCP) synovial lining of the joints (synovitis).10,12
Rheumatoid arthritis less frequently involves the proximal interphalangeal (PIP) joints of the hand; more commonly, the PIP joints are affected by degenerative arthritis. Degenerative arthritis may occur after trauma or infection or may arise as an idiopathic process.1
ANATOMY
Anatomy of the extensor tendon mechanism is shown in FIG 1.
FIG 1 • Anatomy of the extensor mechanism of the finger.
PATHOGENESIS
Rheumatoid arthritis is a multifactorial entity and is poorly understood.
The disease is autoimmune mediated and may occur after a bacterial or viral infection.
There is a hereditary influence.
The B lymphocytes, T lymphocytes, and macrophages lead to proliferation and hypertrophy of synovial cells. The enzymes released by these cells can cause bony erosions, ligamentous laxity, and tendon ruptures.10
MCP joint deformities in rheumatoid patients include ulnar deviation and volar subluxation or dislocation of the proximal phalanx on the metacarpal head (FIG 2).4,11
These deformities occur after synovial proliferation in the recesses between the collateral ligaments and the metacarpal head, attenuating the collateral ligaments.
Radial inclinations of the metacarpals and wrist joint destruction often leads to an ulnar translation of the entire carpus. This translation can cause ulnar and volar extensor tendon subluxation between the metacarpal heads. Ulnar forces generated by the extensor apparatus and volar forces produced by the flexors lead to ulnar drift of the fingers and fixed MCP flexion deformities or volar dislocations of the MCP joints.
Degenerative arthritis affecting the PIP joints of the hand is a process whereby the articular cartilage develops irreversible wear changes, caused by an incompletely understood mechanism. Subchondral bone stiffens and periarticular new bone formation occurs, which leads to restricted joint motion and pain.9
Less commonly, degenerative arthritis can affect the MCP joints of the hand. This can occur after trauma, infection, or osteonecrosis.9
FIG 2 • Ulnar drift of the digits.
NATURAL HISTORY
Rheumatoid arthritis has a variable prognosis based on the severity of the disease and the structures involved. Mild presentations may go undiagnosed for years, while severe presentations may progress to rapid joint destruction in the third or fourth decade of life.
Three clinical stages of rheumatoid arthritis exist.
First, swelling of the synovial lining, which causes pain, warmth, stiffness, redness, and fullness around the joint
Second, synoviocyte hypertrophy and proliferation leading to synovial thickening
Third, enzymatic release causing bone and cartilage destruction, ligamentous laxity, and tendon ruptures
Medical management as well as surgical synovectomy can halt or minimize progression of rheumatoid arthritis in the destructive stage.
PATIENT HISTORY AND PHYSICAL FINDINGS
A thorough patient history and physical examination are important before implant arthroplasty of the fingers.
The surgeon should note the patient’s occupation, hobbies, and expectations.
The history of the patient’s condition is helpful in gauging the progression of the disease.
The primary indication for surface replacement arthroplasty of the MCP or PIP joints is pain relief. Correction of deformity and improvement in function are secondary considerations. Mild deformity may be painful for some, while profound deformity may be painless and functional for others.
Examination of the entire upper extremity should be performed. Although the order of reconstruction is controversial, deficits of the shoulder, wrist, and elbow should be addressed before addressing hand conditions.
Particular attention should be paid to elements of radiocarpal instability or ulnar translation of the carpus. In some situations a wrist arthrodesis may be necessary before performing MCP arthroplasties.
Failure to correct carpal collapse and radial deviation of the metacarpals can result in recurrence of ulnar drift deformity after MCP arthroplasty.
Careful examination of flexor and extensor tendons of the hand and wrist should be performed. The extensor digiti quinti minimi, extensor pollicis longus, and flexor pollicis longus often rupture in more active forms of rheumatoid arthritis.
Extensor tendon or flexor tendon ruptures should be treated before considering implant arthroplasty of the hand.
Examination of the PIP joint should include range-ofmotion assessment of the joint, assessment of volar plate integrity, central slip integrity, and collateral ligament stability.
Normal range of motion of the PIP joint is 0 to 110 degrees.
Varus and valgus stability should be compared to the contralateral side.
Failure of volar plate integrity in rheumatoid arthritis can lead to swan-neck deformity, which is characterized by PIP joint hyperextension, dorsal subluxation of the lateral bands, and flexion of the distal phalangeal joint. The swanneck deformity is considered a relative contraindication for surface replacement arthroplasty of the PIP joint (FIG 3A).
A boutonnière deformity is caused by failure of the central slip mechanism. This can occur in rheumatoid arthritis or after trauma (FIG 3B). It is characterized by flexion of the PIP joint due to central slip incompetence, volar subluxation of the lateral bands, and hyperextension of the DIP joint.
Normal MCP range of motion is between 0 and 90 degrees.
Instability testing: The individual MCP or PIP joints are tested by the examiner grasping the patient’s finger and then applying a valgus and then a varus stress. The resultant motion is compared to the contralateral side. Differences in laxity indicate ligamentous instability. Attempts at hyperextension of the digit at the PIP or the MCP joint can identify volar plate instability and the propensity of the digit to subluxate or dislocate. Surface replacement arthroplasty of either the MCP or the PIP joint is contraindicated in patients with ligamentous instability as these are minimally constrained devices.
Grade 1: No difference in joint line opening compared to the contralateral joint
Grade 2: Notable opening of the joint line compared to the contralateral joint, but a solid “endpoint” is reached
Grade 3: Complete opening of the radial or lateral joint line with valgus or varus stress. This can be demonstrated at either the MCP or the PIP joints. No endpoint can be discerned.
Bunnell test of intrinsic tightness of the PIP joints: The resistance encountered with the MCP joint in this position is compared with the resistance encountered with the MCP joint in the flexed position. An increase of resistance with the MCP joint in the extended position indicates intrinsic tightness of that digit.
FIG 3 • A. Rheumatoid arthritis of the hand demonstrating swan-neck deformities and volar subluxation of the metacarpophalangeal joints. B. Boutonnière deformity of the digit.
It is important to distinguish intrinsic tightness from extrinsic tightness. Extrinsic tightness is encountered when the long extensors of the digits are adherent to either the surrounding soft tissues or the metacarpals. The result is increased resistance to flexion of the PIP joint with the MCP in flexion. In either instance, the limitation of motion is important to clarity as it can affect the outcome of implant arthroplasty of the MCP or the PIP joint.
IMAGING AND OTHER DIAGNOSTIC STUDIES
Posteroanterior, lateral, and oblique views of the hands will adequately image the MCP joints. Brewerton views may add additional information.
Posteroanterior and lateral views are sufficient to image the PIP joints.
DIFFERENTIAL DIAGNOSIS
Psoriatic arthritis
Chronic septic arthritis
Osteomyelitis
Gout
Calcium pyrophosphate dihydrate arthropathy
Articular malunions of the MCP and PIP joints
Scleroderma
Lupus
NONOPERATIVE MANAGEMENT
Nonoperative management in rapidly progressing rheumatoid arthritis is largely ineffective.
In the quiescent forms of rheumatoid arthritis, nighttime wrist and hand splinting in conjunction with medical management may provide pain relief. Various combinations of methotrexate, prednisone, remitting agents, and nonsteroidal anti-inflammatory agents may prove effective for extended periods in certain cases.
During periods of active rheumatoid arthritis of the MCP joints, corticosteroid injections into the joint may provide acute pain relief and improve function in the short term.
The symptoms of MCP and PIP joint degenerative arthritis may come and go, successfully responding to nighttime wrist and hand splinting and nonsteroidal anti-inflammatory agents.
Corticosteroid injection into the MCP and PIP joints for advanced degenerative arthritis seldom provides long-term benefits.
SURGICAL MANAGEMENT
The indications for surface replacement or pyrocarbon MCP arthroplasty are similar to those for flexible MCP implants. These include pain in the face of deformity and worsening function.
Surface replacement implants are designed to recreate the anatomy of a native joint, potentially resulting in greater stability than with flexible MCP implants.
The enhanced stability of these implants is best demonstrated in the index and long fingers, where flexible MCP implants are prone to failure.
Contraindications to surface replacement implant arthroplasty of the MCP joint include infection, lack of adequate bone stock, insufficient radial or ulnar collateral ligament support, lack of adequate soft tissue coverage, and excessively small metacarpal or proximal phalanx medullary canals.
These implants rely on intact soft tissue elements. This includes functioning flexors and extensors as well as intact radial and ulnar collateral ligaments.
Indications for PIP joint surface replacement arthroplasty are pain and diminishing function in the context of advanced radiographic articular degeneration.1,7
Contraindications to PIP joint surface replacement arthroplasty include inadequate bone stock of either the proximal or the middle phalanx, ulnar or radial collateral ligament insufficiency, acute or chronic infection, inadequate soft tissue coverage, insufficient digital flexor function, or disruption of the extensor central slip insertion on the middle phalanx.
Relative contraindications include the presence of a static swan-neck8 or boutonnière deformity.
In general PIP joint surface replacement arthroplasty is not indicated in patients with rheumatoid arthritis.
The importance of postoperative therapy should be emphasized. To ensure that the implants heal with a stable and a functional range of motion the patient must wear a combination of static and dynamic splints for several weeks to months after. Patients must also be aware that heavy lifting or gripping must be avoided indefinitely.
Preoperative Planning
Sizing templates with a 3% parallax enlargement are available for MCP and PIP joint systems and should be used preoperatively to give the surgeon an idea of the size implant required.
Positioning
The patient is positioned supine with the arm placed on an armboard for either MCP or PIP joint surface replacement arthroplasty.
A nonsterile tourniquet is placed proximal to the drapes on the arm.
The hand is pronated to allow access to the dorsum.
Approach
For MCP surface replacement arthroplasty, two different incisions can be used.
A transverse incision across the dorsum of the hand, centered over the MCP joints, will facilitate access to multiple joints.
Alternatively, multiple longitudinal incisions can be used to address all four MCP joints.
If a single joint is being addressed, a longitudinal incision should be used.
For PIP joint surface replacement arthroplasty, a midline longitudinal incision is preferred.
Alternative approaches include the lateral approach and the volar approach.
techniques
METACARPOPHALANGEAL JOINT SURFACE REPLACEMENT ARTHROPLASTY
Exposure
Incise the extensor hood just ulnar to the extensor mechanism.
Carry dissection down through the subcutaneous tissue to expose the extensor tendons.
Preserve the dorsal veins.
Retract the extensor hood and extensor mechanism radialward.
In the rheumatoid patient, the extensor tendon ulnarly translates with destruction of the radial sagittal band. If possible, dissect the sagittal bands from the capsule and preserve them so that the extensor tendon can be relocated and the sagittal bands imbricated at the end of the procedure in order to maintain a centralized extensor tendon position.
Incise the remnants of the MCP joint capsule and use small Hohmann retractors to deliver the head of the metacarpal into the wound.
After the joint is exposed, perform a synovectomy, carefully preserving the collateral ligaments.
If the joint is irreducible, it may be necessary to release one or both collateral ligaments from their origins.
Tag the ends of the collateral ligaments for later repair to their tuberosity origins.
Joint Preparation and Trial Implant Insertion
Use a metacarpal sizing template to identify the appropriate amount of metacarpal head to be resected.
Remove the metacarpal head by first making a vertical saw cut distal to the collateral ligaments. A second cut oriented 45 degrees proximally and volarly removes the remainder of the metacarpal head, retaining the collateral ligament origins.
Remove the articular surface along with a small portion of the base of the proximal phalanx, preserving the collateral ligaments (TECH FIG 1A).
Contracture of the ulnar capsule may require detaching the ulnar collateral ligament to achieve alignment of the finger in some circumstances.
Insert an awl into the dorsal aspect of the intramedullary canal of the metacarpal (TECH FIG 1B).
Perform sequential broaching for the metacarpal until a proper fit has been attained.
For the index and long finger, the broaching is slightly ulnarly displaced. This provides a better moment arm for the radial intrinsic and extrinsic tendons to compensate for ulnar drift.
Repeat the broaching in a similar fashion for the proximal phalanx.
A plastic impactor with a concave surface aids insertion of the metacarpal proximal trial component.
The tip of the prosthesis should pass the midpoint of the metacarpal.
Avoid forceful impaction in order to avoid fracture.
A convex impactor aids insertion and seating of the distal component.
Once the trial components are inserted and the joint is reduced, check component fit and position using an image intensifier. Then assess range of motion, component tracking, and stability.
Revisions of bone cuts may be necessary for soft tissue balancing and to ensure adequate range of motion.
If release of the collateral ligaments was required, drill two holes through the tuberosity at the dorsal radial and dorsal ulnar aspect of the remaining metacarpal head for reattachment of the ligaments. Insert sutures for repair of the collateral ligament (4-0 Ticron/Mersilene).
TECH FIG 1 • A. Exposure of the metacarpophalangeal (MCP) joint demonstrating the bone cuts for preparation of MCP surface replacement arthroplasty. B. Broaching of the metacarpal preparing for MCP surface replacement arthroplasty. (Courtesy of Small Bone Innovations, Morrisville, PA.)
Final Implant Insertion
Irrigate the intramedullary canal with saline and 0.5% neomycin solution, then dry it.
Inject polymethylmethacrylate (PMMA) in a liquid state into the metacarpal and the proximal phalanx using a size no. 14 plastic angiocath catheter attached to a 10-cc syringe.
Under some circumstances “finger packing” may be necessary.
Insert the distal component first. Convex and concave plastic impactors are provided to assist in implant insertion (TECH FIG 2).
Avoid impacting with metallic instruments, which can accelerate prosthetic wear.
The joint is extended and viewed under the image intensifier before allowing the cement to harden so that lastminute corrections in alignment can be made.
Cement fixation of one finger at a time is advisable if positioning is difficult.
If multiple MCP joints are to be implanted, it may be easier to do the distal components as a group, followed by the proximal components.
After the cement has cured, check passive range of motion to ensure adequate range without impingement or prosthetic binding.
TECH FIG 2 • Insertion of the metacarpal component of the metacarpophalangeal surface replacement arthroplasty. (Courtesy of Small Bone Innovations, Morrisville, PA.)
Closure and Soft Tissue Balancing
After hardening of the cement, tighten the collateral ligaments or reattach them to the tuberosity of the metacarpal head with nonabsorbable suture.
Ensure proper radial and ulnar stability as well as rotational alignment before securing the sutures.
Close any remaining capsule with absorbable suture before extensor apparatus closure.
Centralize the extensor tendon and imbricate the radial sagittal bands in rheumatoid hands using nonabsorbable suture.
A pants-over-vest centralization of the sagittal bands may be required in moderate to severe ulnar drift along with intrinsic releases or crossed-intrinsic transfers (TECH FIG 3).
With the finger held in slight overcorrection, imbricate the radial sagittal band over the extensor tendon.
The skin is closed in a routine manner and a splint is applied with the MCP joints in slight flexion.
TECH FIG 3 • Radially directed “pants-over-vest” reefing of the extensor mechanism after metacarpophalangeal surface replacement arthroplasty. (Courtesy of Small Bone Innovations, Morrisville, PA.)
PROXIMAL INTERPHALANGEAL JOINT SURFACE REPLACEMENT ARTHROPLASTY
Exposure
Through a midline longitudinal incision, reflect the extensor tendon distally by creating a distally based flap, as described by Chamay2 (TECH FIG 4A).
Identify and incise remnants of the dorsal PIP joint capsule.
Protect the radial and ulnar collateral ligaments using small Hohmann retractors while bringing the articular surface of the middle phalanx into view.
Joint Preparation and Trial Implant Insertion
Resect the proximal phalanx head by an osteotomy performed 90 degrees to the long axis of the proximal phalanx, just proximal to the most proximal extent of the articular surface (TECH FIG 4A).
During the osteotomy, protect the origins of the radial and ulnar collateral ligaments by using small retractors or by hyperflexing the joint.
It may be necessary to release a small portion of the proximal phalangeal origin of the collateral ligaments to facilitate the proximal phalangeal osteotomy and prosthesis insertion.
Minamikawa et al8 have shown that the PIP joint remains stable after removal of 50% of the collateral ligament substance.
While protecting the volar plate with a small retractor, use a 2-mm burr to assist in making a small back cut (or chamfer cut) to accept the posterior aspect of the prosthetic condyles of the proximal phalangeal component.
This can also be accomplished with the oscillating saw, but that can place the volar plate at risk.
Make a perpendicular osteotomy at the base of the middle phalanx with a small rongeur and remove no more than 1 to 2 mm of bone.
Protect the collateral ligament insertions with small retractors or by hyperflexing the digit.
Broach the proximal and middle phalanges with specific and sequential instruments.
Broach the proximal and middle phalanges to the largest size possible (TECH FIG 4B).
Undersized components can result in limited motion due to bony impingement during flexion.
Insert the trial components using proximal and middle phalanx-specific impactors.
The components are not modular and are generally not interchanged. Under certain circumstances, such as revision surgery, it is permissible to implant unmatched sizes, but no more than one size up or one size down should be used.
After trial component insertion, examine the digit for implant position, range of motion, and stability as detailed for the MCP joint. Make appropriate adjustments.
Final Implant Insertion and Closure
Implant the permanent components by “press-fit” using the “no-touch” technique.
Cementing is discouraged except perhaps in cases with capacious canals or in patients with substantial bone loss or articular erosion. In these circumstances, the prosthetic stems and flanges are simply coated with cement. Excessive cement packing into the medullary canal is not necessary.
Another technique is to pack the canal with morselized allograft bone. This is analogous to the Ling technique described for revision total hip arthroplasty.5
TECH FIG 4 • A. Proximal phalanx exposed using the Chamay approach. An oscillating saw is used to accomplish an osteotomy in preparation for the proximal interphalangeal joint surface replacement arthroplasty placement. B. Broaching of the proximal phalanx in preparation for proximal interphalangeal joint surface replacement arthroplasty.
Using specific impactors, seat the permanent components (TECH FIG 5).
Repair the extensor mechanism with 3-0 Surgilon suture.
Release the tourniquet before skin closure.
The patient leaves the operating room with a sterile dressing, splinted in extension.
TECH FIG 5 • Insertion of the proximal phalangeal component of the proximal interphalangeal surface replacement arthroplasty. (Courtesy of Small Bone Innovations, Morrisville, PA.)
POSTOPERATIVE CARE
Postoperatively the MCP joints should be placed in slight flexion and the PIP joints in about 45 degrees of flexion. If there was ulnar deviation before surgery, the fingers should be placed in 10 degrees of radial deviation.
The dressing is removed 2 to 4 days after surgery and a dynamic splint is applied for daytime exercises. A static rest or nocturnal splint capable of holding the fingers in the corrected position is used for 4 to 6 weeks.
The rehabilitation program is enhanced by the close supervision of a hand therapist. The first week of therapy is best carried out with daily supervision.
Follow-up examinations should include range-of-motion assessment for all the joints of the hand and wrist. Static deformities, grip strength, and pinch strength should also be assessed and recorded.
Follow-up radiographic examination includes posteroanterior, lateral, and oblique views of the hand. Any residual deformity should also be assessed and recorded.
For the PIP joint surface replacement arthroplasty, a controlled rehabilitation protocol is needed to prevent central slip failure.
Initiation of formal postoperative rehabilitation is encouraged by postoperative day 5. A dynamic extension splint permitting active flexion is applied at this time and used for about 6 weeks. A static forearm-based digital extension splint is used at bedtime.
During the first 2 weeks after surgery, PIP flexion is limited to 30 degrees.
Flexion to 60 degrees is allowed beginning at 4 weeks.
By 6 weeks, the extension outrigger splint is discontinued and unrestricted flexion and extension is permitted.
The static bedtime splint is used for an additional 6 weeks. Heavy lifting or gripping is not permitted.
OUTCOMES
Initial results after 76 PIP joint surface replacement arthroplasties were published.6
At a mean follow-up of 4.5 years, 32 joints had good results, 19 fair, and 25 poor.
Better results were obtained with arthroplasties performed through a dorsal approach rather than the volar approach.
Range of motion at follow-up averaged −14 degrees of extension and 61 degrees of flexion. There was a 12-degree improvement in the flexion–extension arc compared to the preoperative examination.
The MCP joint surface replacement arthroplasty (Small Bone Innovations, Morrisville, PA) has been available in Europe for 8 years and is under clinical trial in the United States. No series has been published reporting results of this implant. Although from a theoretical perspective there are advantages to the use of the MCPJ surface replacement arthroplasty, it currently cannot be considered a replacement for the Swanson Silastic MCP joint spacer.
Previous primate studies have shown no evidence of debris or inflammatory reaction after implantation of the pyrolytic carbon MCP joint arthroplasty. Good bone incorporation of the prosthesis was also observed.
In contrast to the Small Bone Innovations MCP joint surface replacement arthroplasty, a series of 151 pyrolytic carbon MCP prostheses (Ascension Orthopaedics, Austin, TX) implanted over an 8-year period, mostly in patients with rheumatoid arthritis, have been followed for an average of 11.7 years.3
The arc of MCP joint motion improved an average of 130 degrees.
The 10-year survivorship was 81.4%.
At follow-up, the degree of digital ulnar drift was the same as preoperative.
Complications led to 18 implant revisions (12%).
COMPLICATIONS
PIP
Failure of the central slip can occur, resulting in extensor lag or, more commonly, a flexion contracture or boutonnière deformity.
With the volar approach, failure of the volar plate may occur, leading to swan-neck deformity.
Tenodesis as well as joint instability and joint subluxation can occur.
Postoperative infection or prosthesis loosening is seldom seen.6
MCP
Stiffness
Loosening
Subluxation
Proliferative synovitis
REFERENCES
1. Amadio PC, Murray PM, Linscheid RL. PIP arthroplasty. In: Morrey BF, ed. Joint Replacement Arthroplasty, 3rd ed. Churchill Livingstone, 2003:163–174.
2. Chamay A. A distally based dorsal and triangular tendinous flap for direct access to the proximal interphalangeal joint. Ann Chir Main 1988;7:179–183.
3. Cook SD, Beckenbaugh RD, Redondo J, et al. Long-term follow-up of pyrolytic carbon metacarpophalangeal implants. J Bone Joint Surg Am 1999;81A:635–648.
4. Flatt AE. Some pathomechanics of ulnar drift. Plast Reconstr Surg 1966;37:295–303.
5. Halliday BR, English HW, Timperley AJ, et al. Femoral impaction grafting with cement in revision total hip replacement: evolution of the technique and results. J Bone Joint Surg Br 2003;85B:809–817.
6. Linscheid RL, Murray PM, Vidal MA, et al. Development of a surface replacement arthroplasty for proximal interphalangeal joints. J Hand Surg Am 1997;22A:286–298.
7. Linscheid RL. Implant arthroplasty of the hand: retrospective and prospective considerations. J Hand Surg Am 2000;25A:796–816.
8. Minamikawa Y, Horii E, Amadio PC, et al. Stability and constraint of the proximal interphalangeal joint. J Hand Surg Am 1993;18:198–204.
9. Murray PM. New-generation implant arthroplasties of the finger joints. J Am Acad Orthop Surg 2003;11:295–301.
10. Smith RJ, Kaplan EB. Rheumatoid deformities at the metacarpophalangeal joints of the fingers: a correlative study of anatomy and pathology. J Bone Joint Surg Am 1967;49A:31–37.
11. Stack HG, Vaughan-Jackson OJ. The zigzag deformity in the rheumatoid hand. Hand 1971;3:62–67.
12. Wilson RL, Carlblom ER. The rheumatoid metacarpophalangeal joint. Hand Clin 1989;5:223–237.