Pitfalls

• Inadequate soft tissue balancing and poor hand therapy can lead to recurrence of the deformities and subluxation of these joints.

• Use of silicone implants can lead to an inflammatory response with subsequent erosive changes.

Diagnostic Studies

Radiographs of the hand to include posteroanterior (PA) (Fig. 73-2), lateral, and oblique views demonstrate subluxation and joint destruction of the MP joints in the index through small fingers of the right hand. Though there is relative diffuse osteopenia present, adequate bone stock appears present for potential implant arthroplasty.

Osteopenia Diffusa
Figure 73—1. A classic ulnar drift and extension deficit in a rheumatoid hand seen at the metacarpophalangeal joints. (Illustration courtesy of The Indiana Hand Center and Gary Schnitz.)
Oblique Thumb Radiograph

Figure 73—2. Posteroanterior (PA) radiograph of metacarpophalangeal (MP) subluxation and joint destruction.

Differential Diagnosis

Degenerative joint disease Rheumatoid arthritis Septic joints

Figure 73—2. Posteroanterior (PA) radiograph of metacarpophalangeal (MP) subluxation and joint destruction.

Diagnosis

Rheumatoid Destruction and Deformity of the Index through Small Finger MetacarpalphalangealJoints

The MP joint in the rheumatoid hand is commonly affected by joint destruction and deformity. Typically, the disease process involves bony articular destruction, and ulnar and volar capsular contracture with concordant radial capsular attenuation. This subsequently results in subluxation of the flexor sheath in an ulnar and volar direction in addition to ulnar displacement of the common extensor tendon. Intrinsic tightness contributes to overall dysfunction. Indications for arthroplasty reflect the disease process and include pain and disability with radiographic evidence of joint destruction, limited MP range of motion secondary to contracted myotendinous and ligamentous supports, ulnar drift that has failed other soft tissue procedures, and stiff distal interphalangeal (DIP) or PIP joints. Arthroplasty of the MP joint predictably addresses these processes and maintains function better than arthrodesis or simple resectional arthroplasty in patients with adequate bone stock, soft tissue coverage, and absence of preexisting infection.

Metacarpophalangeal destruction and deformity are often accompanied by PIP joint deformity and wrist collapse. Timing of surgical interventions as well as consideration of other joint involvement (e.g., hip and knee involvement/shoulder and elbow involvement) requiring further load bearing on the diseased upper extremity following surgery must be noted. With associated wrist involvement, reconstruction of the wrist followed by the MP joint is appropriate. The exception is in the face of an extensor tendon rupture with decreased passive MP range of motion. Metacarpophalangeal arthroplasty should be performed first to gain passive motion in association with the extensor tendon repairs at the level of the wrist.

Surgical Management

A transverse or longitudinal skin incision is created dorsally over the region of the metacarpal necks. The dorsal veins are preserved and the extensor hoods to each digit are exposed with care to protect the neurovascular structures radially and ulnarly. The extensor tendon is identified and is usually subluxed ulnarly with attenuation of the extensor tendon at its radial aspect (Fig. 73—3). The extensor hood is longitudinally incised ulnar to the common extensor tendon in the middle and ring fingers, and between the common extensor and the ulnar capsular ligament of each digit. Associated capsular tissue is released distally to adequately allow the base of the proximal phalanx to be dislocated dorsal to the metacarpal. The radial collateral ligament of each digit is preserved if possible. With the MP joint placed into flexion, the metacarpal neck is exposed subperiosteally and transversely osteotomized using a microair saw (Fig. 73—4). Care is taken to leave part of the metaphyseal flare for support of the prosthesis. Proliferative synovium along with the transected metacarpal head is completely removed (Fig. 73—5). Attention is then directed toward the base of the proximal phalanx where all cartilaginous surfaces are removed in addition to any marginal osteophytes. The volar plate is identified and released from its attachment at the base of the proximal phalanx. In all but the index finger it is then completely resected. In the index finger it will be used in conjunction with the radial collateral ligament for later capsular reconstruction. Release and resection of the volar plate allow further identification of the underlying flexor sheath. An incision is made into the flexor sheath with subsequent delivery of the flexor tendon into the wound using a blunt hook. Hypertrophic tenosynovium is then removed. Evaluation of appropriate tendon excursion following the tenosynovectomy will determine whether flexor tendon exploration on the palmar aspect of the hand over the A1 and A2 pulleys is

Hand And Finger Tendons
Figure 73—3. Synovial reaction withpannus and subluxation of the extensor tendon at the MP joint.
Tenosynovectomy
Figure 73—4. Clinical photo (A) and drawing (B) demonstrating transversely osteotomized metacarpal neck of the index finger. (Illustration courtesy of The Indiana Hand Center and Gary Schnitz.)

necessary. This is typically done using a palmar/digital zigzag-type of incision with care to preserve the A1 and A2 pulleys in the index and long fingers to avoid further ulnar subluxation of these tendons. The ulnar intrinsic tendon in all but the index finger is also delivered into the wound and incised at its myotendinous junction typically at the level of the MP joint. In the index finger, preservation of the ulnar intrinsic tendon is recommended to help maintain supination in this digit for pinching function. This pinching function is further reinforced by reconstructing the radial collateral ligament of the index and long finger by using the collateral ligaments and capsule. The ulnar collateral ligament, which has previously been divided at its insertion at the proximal phalanx, is now further mobilized by dissection proximally on the metacarpal, with care taken to maintain its attachment. Similarly, the previously preserved radial collateral ligament is dissected as a unit with the overlying capsule from its distal insertion. These capsular tissues may be tagged and retracted for later reconstruction using a 2—0 Dacron suture.

With regard to the small digit MP joint, the abductor digits minimi tendon is isolated and sectioned with care to protect the ulnar neurovascular structures. The proximal end of the abductor digiti minimi tendon is then attached to the flexor digiti minimi tendon immediately volar in position to the abductor digiti minimi.

The intramedullary canal of the metacarpal and proximal phalanx is then reamed in a rectangular fashion centrally in the canal using a combination of

Gary Schnitz Hand

Figure 73—5. Synovium removed from transected metacarpal head. (Illustration courtesy of The Indiana Hand Center and Gary Schnitz.)

Essentials of Human Physiology

Essentials of Human Physiology

This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.

Get My Free Ebook


Responses

  • temesgen
    What is radial drift at distal phalanx at distal dip?
    4 years ago

Post a comment