75: Scaphotrapeziotrapezoid Arthrodesis and Lunate Excision with Replacement by Palmaris Longus Tendon

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Procedure 75 Scaphotrapeziotrapezoid Arthrodesis and Lunate Excision with Replacement by Palmaris Longus Tendon

Indications

Advanced avascular necrosis of the lunate from late stage IIIA to early stage IV according to the Lichtman preoperative 5-stage classification.

This procedure is mainly indicated for stage IIIB Kienböck disease, which is associated with carpal collapse with a fixed palmar scaphoid flexion.

A radiograph showing generalized arthrosis is not suitable for scaphotrapeziotrapezoid (STT) arthrodesis and lunate excision with replacement by the palmaris longus tendon.

This procedure is contraindicated in patients with preoperative advanced osteoarthrosis between the radius and scaphoid because of the risk for further progression of osteoarthrosis at the radioscaphoid joint.

Examination/Imaging

Clinical Examination

A complete examination of the involved and contralateral extremity is indicated, especially if the patient has a history of autoimmune disease or infection.

Documentation of baseline pinch and grip strength is helpful.

Attention to soft tissue swelling must be given because some patients have associated capsular inflammation, thickening, and synovitis.

Pain can be elicited in all directions of motion, and frequently there is a notable decrease in the arc of motion, particularly in extension.

Degree of pain, range of motion of the wrist, and grip strength of both wrists should be meticulously measured preoperatively to evaluate postoperative results.

Imaging

Plain Radiographs

Staging: Lichtman modification of Stahl staging

• Stage 0: Radiographs are normal, and magnetic resonance imaging (MRI) may show lunate density changes, edema, or fracture (according to the Amadio modified Lichtman staging based on MRI findings).

• Stage I: Radiographs are normal, but bone scan or tomograms may reveal a sclerotic line representative of a lunate fracture. Occasionally, an indistinct line consistent with the fracture may be visible on plain films (Fig. 75-1A).

• Stage II: Lunate density changes are apparent, but carpal alignment remains normal, and lunate size is preserved (Fig. 75-1B).

• Stage IIIA: Plain films demonstrate lunate collapse, fragmentation, and displacement; on anteroposterior and lateral views, lunate elongation may be seen without static carpal collapse (Fig. 75-1C).

• Stage IIIB: Lunate collapse is accompanied by carpal collapse with a fixed palmar scaphoid flexion (Fig. 75-1D).

• Stage IV: All stage III findings are present plus generalized arthritis (Fig. 75-1E).

Posteroanterior (PA) and lateral radiographs with the wrist in neutral rotation and neutral flexion-extension (Fig. 75-2).

Ulnar variance radiographic views with the wrist in full pronation and full supination. The carpal height ratio is measured from PA view with the wrist in neutral position. The Stahl index is also measured from lateral view.

Lunate sclerosis, carpal instability patterns, and fragmentation are seen.

Shortened scaphoid in the long axis and cortical ring sign of the scaphoid are seen in stage IIIB, which indicates scaphoid in flexed position.

Evaluation of relationship among scaphoid, trapezium, and trapezoid.

FIGURE 75-1

FIGURE 75-2

Computed Tomography

Computed tomography (CT) is needed to evaluate precisely the bony architecture of the lunate and the remainder of the carpus to determine which procedure is indicated and to determine whether arthritic changes of the midcarpal and radiocarpal joints are present.

A CT scan is useful for evaluation of fragmentation or fracture patterns and associated collapse.

Magnetic Resonance Imaging

MRI will show decreased uptake in both T1- and T2-weighted images. Gadolinium contrast has improved diagnosis and evaluation of lunate vascularity (Fig. 75-3).

It is important to differentiate between ulnar impaction of the lunate and true Kienböck disease.

Stage 0 has been proposed when lunate edema is visible on MRI only. MRI can show the degree of devascularization or revascularization.

FIGURE 75-3

Bone Scan

A three-phase bone scan is useful to determine the blood flow to the lunate. This scan is highly sensitive, but specificity is low.

Positioning

The patient is placed in supine position with the involved extremity on a hand table.

A pneumatic tourniquet is placed high on the operative arm.

The table is oriented to allow for intraoperative fluoroscopy.

Procedure

Superficial branches of the radial nerve are retracted during the procedure.

Through the proximal half of the incision, the extensor retinaculum is exposed. The capsular flap is incised between the third and fourth dorsal compartments to expose the lunate (Fig. 75-5).

The lunate is removed piecemeal or entirely in one piece, with great care to avoid injury to the palmar wrist ligaments (Fig. 75-6).

An ipsilateral palmaris longus tendon is removed with a tendon stripper.

The tendon strip is rolled into a “rugby ball,” sutured to itself, and inserted into the defect of the excised lunate.

The dorsal capsule is closed securely (Fig. 75-7).

FIGURE 75-5

FIGURE 75-6

FIGURE 75-7

Instrumentation/Implantation

Various types of small osteotomes and chisels are useful to remove the cortex of scaphoid, trapezium, and trapezoid. A low-powered surgical bur is also convenient to expose cancellous bones between the scaphoid, trapezium, and trapezoid.

A hand-held drill is necessary to insert K-wires between the scaphoid, trapezium, and trapezoid.

Step 1 Pearls

Consider excision of a 1-cm segment of the posterior interosseous nerve to denervate the dorsal wrist capsule to decrease pain.

Step 1 Pitfalls

The lunate is ideally removed as one bone, although this is not easy. Therefore, we prefer to remove the lunate piecemeal.

The palmar wrist capsule and ligaments are protected during removal of the lunate.

If the palmaris longus tendon is absent, the plantaris tendon or a half slip of the extensor carpi radialis longus tendon is harvested.

Step 2

Through the distal half of the incision, the wrist and thumb extensors are exposed.

Wrist and thumb extensors are retracted.

The articular surfaces between the scaphoid, trapezium, and trapezoid are exposed.

The articular cartilage and subchondral bone of the three joints are removed to expose the cancellous bone (Fig. 75-8).

Cancellous bone from the iliac crest is grafted into the joint spaces to prevent shortening of the carpus (Fig. 75-9).

FIGURE 75-8

FIGURE 75-9

Step 2 Pearls

Removal of the cortex between the scaphoid, trapezium, and trapezoid and packing of the cancellous bone graft from the iliac crest into the three joint spaces should be performed to obtain solid fusion.

Step 2 Pitfalls

Care should be taken to avoid injury to the flexor carpi radialis and flexor pollicis longus tendons when the three points are being prepared for arthrodesis.

K-wires should be inserted with care to avoid injury to the branches of the superficial radial nerve.

Step 3

The proximal pole of the scaphoid is depressed until it is under the dorsal surface of the lunate fossa on the radius to reduce the flexed posture of the scaphoid. This distal pole is pulled dorsally, if necessary, and K-wires are then driven percutaneously through the scaphoid into the capitate to maintain reduction (see Fig. 75-9).

The position of the scaphoid is confirmed by intraoperative imaging (Fig. 75-10).

Figure 75-10A shows a preoperative radiograph of Kienböck disease classified by stage IIIB.

Figure 75-10B shows a radiograph of the excision of the lunate.

Figure 75-10C shows a radiograph of an STT arthrodesis after the removal of the lunate.

Figure 75-10D shows a radiograph 3 years after excision of the lunate and STT arthrodesis.

FIGURE 75-10

Step 3 Pitfalls

K-wire fixation of the proximal scaphoid to the radius must be avoided because this can greatly decrease motion in the radiocarpal joint and increase the stress at the site of the arthrodesis.

Step 4

Insertion of K-wires (size: 1.2 mm) only into the scaphoid, trapezium, and trapezoid.

Step 4 Pearls

Watson emphasized that the scaphoid should lie about 45 degrees to the long axis of the forearm in the lateral projection. We emphasize the importance of the radioscaphoid angle in STT arthrodesis to prevent late postoperative arthrosis at the radioscaphoid joint.

Step 5

The tourniquet is released, and meticulous hemostasis is achieved by using a bipolar coagulator. The dorsal capsule is closed.

The wound is irrigated, and skin closure of the surgeon’s choice is performed.

Postoperative Care and Expected Outcomes

The patient is placed in a well-padded short-arm thumb spica splint with the thumb in maximal opposed position and the wrist and forearm in neutral positions.

The patient is given instructions on routine splint care, told to maintain a non–weight-bearing status for the upper extremity, and encouraged to work on gentle finger range-of-motion exercises.

The postoperative splint is removed about 2 weeks after surgery. The wound is examined, and sutures are moved. The patient is then placed in a short-arm thumb spica cast. Finger range of motion is assessed to determine whether stiffness of the interphalangeal or metacarpophalangeal joints has developed.

Six weeks after surgery, the patient’s cast is removed, and unions among three bones are evaluated by plain radiographs or CT. A short-arm thumb spica cast is applied until arthrodesis is obtained.

The patient is re-evaluated 10 or 12 weeks after surgery. Union should be achieved at this point. If so, the patient is not placed in a cast but rather is given a removable splint for comfort and to protect the surgical site. Wrist range of motion is emphasized.

Minami A, Kato H, Suenaga N, et al. Scaphotrapezio-trapezoid fusion: long-term follow-up study. J Orthop Sci.. 2003;8:319-322.

The authors evaluated clinical and radiologic results of 30 STT fusions in 30 patients (23 with Kienböck disease, 6 with isolated STT osteoarthroses, and 1 dislocation of the trapezium) with mean follow-up of 84 months. Twenty-six patients returned to their previous activities. STT fusion is an effective procedure for Kienböck disease and isolated STT arthrosis, although radioscaphoid arthrosis occurred in 23% of this series. (Level III evidence)

Minami A, Kimura T, Suzuki K. Long-term results of Kienböck’s disease treated by triscaphe arthrodesis and excisional arthroplasty with a coiled palmaris longus tendon. J Hand Surg [Am]. 1994;19:219-228.

Fifteen patients with Kienböck disease (stages IIIA:1, IIIB:11, and IV:3) were treated with STT arthrodesis and lunate excisional arthroplasty and a coiled palmaris longus tendon replacement, with average follow-up period of 57 months. Five patients revealed postoperative progress of osteoarthritic changes at the radioscaphoid joint. The authors concluded that stage IIIB is a specific indication for STT arthrodesis. (Level IV evidence)

Watson HK, Ryu J, DiBella A. An approach to Kienböck’s disease: Triscaphe arthrodesis. J Hand Surg [Am]. 1985;10:17-87.

Sixteen patients with Kienböck disease were treated with STT arthrodesis (fusion of the scaphoid, trapezium. and trapezoid) with or without silicone rubber lunate arthroplasty. After an average follow-up of 20.5 months, relief of pain was satisfactory in all 16 patients. (Level IV evidence)

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Operative Techniques Hand and Wrist Surgery