Proximal Row Carpectomy

Videos corresponding to this chapter are available on DVD and online.

INTRODUCTION

The scapholunate advanced collapse (SLAC) wrist and the scaphoid nonunion advanced collapse (SNAC) wrist represent two of the most common patterns of wrist degeneration. Originally described by Watson and Ballet, the arthritic changes in wrists with longstanding scapholunate ligament incompetence or scaphoid nonunion advance in a predictable and progressive pattern. The earliest signs of wear appear between the radial styloid and the scaphoid. The progressive loss of joint space then expands to involve the entire scaphoid fossa. Finally, the carpus collapses as the capitate begins to migrate proximally into the scapholunate interval with associated capitolunate joint degeneration. The radiolunate joint is universally preserved.

First described by Mr. T.T. Stamm in 1944, proximal row carpectomy has now become an established surgical treatment for SLAC and SNAC arthritis. When treating these conditions, debate continues as to the superiority of proximal row carpectomy over scaphoid excision and four-corner fusion (capitate-hamate-lunate-triquetrum). Advocates of proximal row carpectomy cite the technical ease, the lack of reliance on hardware, and the need for only soft tissue healing. Others raise potential concerns regarding incomplete pain relief, lost grip strength secondary to relative lengthening of the extrinsic flexors, and subsequent degeneration between the distal radius and the proximal capitate. In our hands, proximal row carpectomy has performed well for most patients and has provided pain relief while preserving a functional arc of wrist motion.

INDICATIONS FOR PROXIMAL ROW CARPECTOMY

A proximal row carpectomy is indicated to address focal radiocarpal degeneration, which represents the common endpoint of several conditions. This surgery has been performed to treat SLAC and SNAC degeneration as well as the late sequelae of Kienböck’s disease, perilunate dislocations, and avascular necrosis of the scaphoid ( Fig. 38-1 A and B). It is less frequently used to treat acute carpal fracture dislocations, to address spastic deformation, and to salvage failed carpal implants.

Although the radiographic evidence of SLAC and SNAC degeneration is clear, it is important to correlate x-rays with history and physical examination findings. Patients present to hand surgeons with complaints that are wide ranging and potentially unrelated to arthritis in the wrist. Only patients with symptoms reasonably explained by their arthritis should be considered for surgical treatment. Persistent severe wrist pain, after having failed anti-inflammatory medication and immobilization, is the most common indication for surgical intervention. In our opinion, a proximal row carpectomy should be delayed until symptoms develop because after the onset of arthritis there is no definable period of time beyond which the procedure’s results are compromised and because this surgery appears to fare better with advancing patient age.

CONTRAINDICATIONS

Proximal row carpectomy is contraindicated in several instances. When the head of the capitate and/or the lunate fossa of the distal radius shows loss of articular cartilage, a proximal row carpectomy should not be performed. This is fairly intuitive provided that these cartilage surfaces are going to be relied on to make up a novel, pain-free radiocarpal articulation. However, defining the exact degree of cartilage damage that will predict failure after proximal row carpectomy is debated. Commonly reported in the classic literature is that any damage to these surfaces necessitated an alternative surgical procedure. However, contemporary clinical series have noted successful outcomes despite a range of qualitatively defined damage to the capitate and lunate fossa cartilage. The most consistently cited quantified assessment of these surfaces is provided by Imbriglia and colleagues, who reported that peripheral abrasion or fibrillation, or central full-thickness cartilage lesions less than 3 mm in diameter, were considered acceptable for proximal row carpectomy.

Relative contraindications to proximal row carpectomy are patients with inflammatory arthritis (most commonly rheumatoid arthritis) and patients younger than 35 years of age. Inflammatory arthritic conditions produce pervasive cartilage damage, anticipated to affect both the lunate fossa and the head of the capitate. Although proximal row carpectomy has been successfully performed on young patients (under 35 years of age), the long-term experience published from the senior author (PJS) has been that all clinical failures in his series were in those younger than 35 at the time of surgery. This finding has led us to discourage proximal row carpectomy in the younger population. Ulnar translocation of the carpus would be another relative contraindication. Proximal row carpectomy should be approached with caution in a patient with a history of a radial styloidectomy because of the risk of previous injury to the radioscaphocapitate ligament.

TECHNIQUE

Although traditionally performed from an open dorsal approach, proximal row carpectomy has been described both with a palmar approach and as an arthroscopic procedure. We have not attempted an arthroscopic resection and have only proceeded volarly when using a compounding wound to address an open trans-scaphoid perilunate dislocation. As modifications on the proximal row carpectomy, proximal capitate resection and dorsal capsule interposition are used by some but are not part of our approach. The following technique describes that preferred by the senior author (PJS).

Either a regional block or general anesthesia is used. Some surgeons have noted that the relaxation provided by a general anesthetic aids in visualization; however, the wishes of the patient or the preference of the anesthesiologist can easily be accommodated without compromising the operation. In our experience, a regional block can also serve as a useful adjunct to general anesthesia, reducing the quantity of required intraoperative anesthetic and producing hours of postoperative pain relief.

Although both transverse and curvilinear incisions are possible, we recommend a 7- to 8-cm longitudinal incision over Lister’s tubercle and centered at the radiocarpal joint ( Fig. 38-2 ). Blunt dissection through the subcutaneous tissue in line with the incision is used to prevent injury to the dorsal sensory branch of the radial nerve and dorsal branch of the ulnar nerve. Once down to the level of the extensor retinaculum, full-thickness skin flaps are raised off the retinaculum both radially and ulnarly.

Distal to the retinaculum, the obliquely coursing extensor pollicis longus (EPL) tendon is identified. The extensor pollicis longus is then traced proximally, sharply incising its entire retinacular roof. The extensor pollicis longus tendon is then transposed and retracted radially ( Fig. 38-3 ). The posterior interosseous nerve (PIN) is readily visualized at this point on the radial floor of the fourth dorsal compartment ( Fig. 38-4 ). We routinely excise a 1-cm section of the posterior interosseous nerve as a partial denervation of the wrist. The remaining dorsal compartments are then elevated off the distal radius with subperiosteal dissection in an effort to prevent tendinous adhesions and scarring.

The dorsal wrist capsule is incised longitudinally just ulnar to the extensor carpi radialis brevis (ECRB) tendon, between the second and fourth dorsal compartments. At its most proximal extent, the capsule is transversely incised off the dorsal distal radius, leaving a cuff of capsule of several millimeters for subsequent repair. In essence, this creates an inverted T-shaped capsulotomy with the transverse limbs extending to the radial and ulnar borders of the distal radius. Care must be taken during this capsulotomy not to stray deeply with the knife, inadvertently causing iatrogenic damage to the articular surface of the head of the capitate or the lunate fossa of the distal radius. In addition, careless dissection risks damage to the dorsally coursing radial artery and the triangular fibrocartilage complex (TFCC).

With well-positioned self-retaining retractors, one can now visualize the carpus ( Fig. 38-5 ). The articular surfaces of the proximal capitate and lunate fossa are inspected for gross degeneration ( Fig. 38-6 ). If the cartilage appears inappropriate to serve as the new radiocarpal articulation, the procedure is changed to either a four-corner arthrodesis (capitate-hamate-lunate-triquetrum) with scaphoid excision or a total wrist arthrodesis. Knowing that this decision must be made intraoperatively, the surgical consent should always include these procedures as possibilities. Depending on the degree of preexisting deformity, longitudinal traction on the hand with variable amounts of wrist flexion may be necessary to adequately deliver the bones of the proximal row.