37 Proximal Row Carpectomy for Scaphoid Nonunion
Proximal row carpectomy (PRC) for scaphoid nonunion is a motion preserving salvage operation. As compared with intercarpal arthrodesis, it is simple to perform, avoids the risk of nonunion, requires a short period of immobilization, and rehabilitation is straightforward. Several long-term studies have shown it to be a durable procedure with predictable results.
▪ Indications (Table 37.1)
Proximal row carpectomy as a salvage procedure may be used in a variety of circumstances. The ideal candidate is a relatively low demand patient with age greater than 40 years. Over time, most wrists develop radiographic evidence of radiocapitate arthritis that might limit this procedure as an option in younger patients. In addition, given the fact that this represents a neoarticulation, the stress placed on it by a heavy laborer may accelerate the degeneration at the radiocapitate joint. Relatively low demand patients with stage I or II scaphoid nonunion advanced collapse (SNAC) without capitolunate degenerative disease are optimal candidates (SNAC stage I: radioscaphoid osteoarthritis; stage 2: radioscaphoid and scaphocapitate osteoarthritis; stage 3: radioscaphoid, scaphocapitate, and capitolunate osteoarthritis). Typically, the integrity of the articular cartilage of the head of the capitate is assessed intraoperatively to ascertain the feasibility of a PRC versus scaphoidectomy and four-corner arthrodesis. Patients who have failed prior surgical intervention for scaphoid nonunion such as bone grafting (vascularized or nonvascularized) as well as distal scaphoid excision are also candidates for a PRC. Finally, patients with proximal pole nonunions, where the fragment is small and/or avascular, may benefit from a proximal row carpectomy as a first-line intervention in these frequently recalcitrant nonunions.
Indications: Proximal Row Carpectomy
1. Relatively low demand patient
2. Age >40 yrs
3. Stage I or II scaphoid nonunion advanced collapse
4. Persistent nonunion following surgical intervention
5. Nonunion with small avascular proximal pole fragments
6. Failed distal pole scaphoid excision
▪ Contraindications (Table 37.2)
Patients with inflammatory arthropathies, such as rheumatoid arthritis, with persistent carpal synovitis, are at risk of developing postoperative ulnar translocation of the carpus secondary to capsular and ligamentous laxity. Culp et al1 reported three patients with rheumatoid arthritis for whom they performed a proximal row carpectomy. All failed within 18 months because of “imbalance, collapse, and pain.” Hence these patients are not candidates for a PRC. Because of the need for formation of a neoarticulation between the capitate and radius, a PRC is prohibited in any patient with degenerative changes of either the lunate facet of the radius or the head of the capitate. We believe that a > 1 cm full-thickness cartilaginous defect is an absolute contraindication to a PRC, and a smaller defect is a relative contraindication.
Contraindications: Proximal Row Carpectomy
1. Inflammatory arthropathy (rheumatoid arthritis)
2. Degenerative change of the lunate facet of the radius
1. Patient age <35 years
2. Scaphoid nonunion without collapse
3. Stage III or greater scaphoid nonunion advanced collapse (SNAC) wrist (capitolunate arthrosis)
4. Limited wrist range of motion
3. Heavy demand patient
4. Full-thickness cartilage loss>1 cm on the head of the capitate
In our experience, patients aged less than 35 years have worse outcomes; thus a PRC should be performed with considerable caution in this age group. Patients with scaphoid nonunion with carpal collapse, stage III or greater SNAC (capitolunate degenerative changes), and heavy-demand patients are likely better served by other procedures, including bone grafting and four-corner fusion. Finally, if a patient already has severely restricted wrist motion, a “motionpreserving” procedure such as a PRC will not likely improve mobility, and a wrist arthrodesis may be a better alternative.
▪ Surgical Technique
The procedure can be performed with either regional or general anesthesia. A standard bone tray with rongeurs, osteotomes, and Steinmann pins (3.2 mm) can be used. The patient is placed supine on the operating room table with a high brachial tourniquet. The arm is abducted at 90 degrees on an arm table. A utilitarian dorsal incision is placed ∼8 cm in length, centered over the Lister tubercle ( Fig. 37.1 ).2 Alternatively, a transverse incision in the dorsal wrist crease halfway between the Lister tubercle and the radial styloid may also be used.
The extensor pollicis longus tendon is identified distal to the extensor retinaculum as it crosses over the radial wrist extensors, dissected free of the third dorsal compartment and retracted radially with umbilical tape ( Fig. 37.2 ).2 A posterior interosseous neurectomy is then performed. The nerve is found beneath the fourth dorsal compartment. A 1 cm segment is sharply resected with a scalpel or with bipolar cautery.
The wrist capsule is entered through a longitudinal incision parallel to the ulnar border of the extensor carpi radialis brevis, with care not to score the hyaline cartilage on the head of the capitate.
Next, T-shaped capsular flaps are created proximally by raising the capsule off of the distal radius in an ulnar and radial direction. Care is taken not to enter the distal radioulnar joint. A subperiosteal dissection is then performed underneath the dorsal extensor compartments. A similar dissection is performed distally, exposing the scaphoid, lunate, and triquetrum ( Fig. 37.3 ).2
At this juncture, the head of the capitate and the lunate facet of the distal radius are inspected to ascertain the quality of the hyaline cartilage on these future contact surfaces. If there is eburnation, alternative procedures such as a four-corner fusion or total wrist arthrodesis need to be considered. Fluoroscopy may be useful in the identification of the proximal row carpal bones if there is any ambiguity regarding their location.
The removal of the proximal row begins with the resection of the scaphoid. To facilitate its removal, a 3.2 mm Steinmann pin is inserted into the scaphoid in a dorsal-proximal to volar-distal fashion to act as a joystick ( Fig. 37.4 ).2 Hohman retractors are then placed beneath the distal pole and sharp dissection is used to separate the scaphoid from its volar capsular attachments. Care must be taken to avoid injury to the radioscaphocapitate ligament that lies at the volar midportion of the scaphoid, extending from the volar radial styloid to the volar capitate. The radioscaphocapitate ligament serves to prevent postoperative ulnar translation of the carpus. Alternatively, the scaphoid may be taken out piecemeal using an osteotome to section the bone parallel to the radioscaphocapitate ligament. A rongeur is then used to resect the fragmented scaphoid.
The lunate and triquetrum are removed next, with care taken not to damage the articular surface of the head of the capitate. The joystick maneuver described earlier may be used with these bones as well.
After resection of the proximal row, the capitate is seated into the lunate fossa of the distal radius ( Fig. 37.5 ).2 We do not place temporary fixation across the new radiocarpal articulation. Previous experience with Kirschner wires resulted in pin tract infections and pin migration. The wrist capsule is then closed with interrupted 2–0 nonabsorbable suture, and intraoperative radiographs are taken to confirm location of the capitate within the lunate fossa of the radius. The extensor pollicis longus tendon is left radially transposed and the extensor retinaculum is closed with 3–0 nonabsorbable suture. No drain is necessary, and the skin is closed with 3–0 absorbable interrupted deep dermal sutures and a running subcuticular 4–0 absorbable suture.
A bulky dressing and volar plaster splint extending from the distal palm to midforearm is fashioned with the wrist in 10 degrees of extension.
The patient is discharged home and returns in 7 to 10 days for a wound check and dressing change. An orthoplast splint is fabricated and worn for 3 to 4 weeks, during which time digital, elbow, and shoulder motion is encouraged. After this period, wrist range of motion is initiated under the supervision of the hand therapist. A splint is worn for another 3 weeks, removed for exercises only. After 6 weeks, no further immobilization is necessary, and a program of strengthening is initiated. At 3 months, the patient may return to full unrestricted activities.
Painful radiocapitate arthritis requiring wrist fusion (7.1%)
Pin track infection (2.8%)
Radial styloid impingement requiring radial styloidectomy (1.2%)
Deep infection (<1%)
Sympathetically maintained pain syndrome (<1%)
Superficial radial or ulnar nerve injury
Ulnar translocation of the carpus