Scaphoid Hemiresection and Arthrodesis of the Radiocarpal Joint

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INDICATIONS AND CONTRAINDICATIONS

Radiocarpal arthritis is frequently due to trauma and/or degenerative changes. The leading causes are malunited or nonunited fractures of the radius or scaphoid, or radiocarpal or intercarpal dislocations or dissociations. Radiocarpal arthritis also may be a form of primary osteo- or inflammatory arthritis. Management of arthritic wrist degeneration has been focused on reducing pain and increasing function. Preserving some degree of motion is preferable, reserving total wrist arthrodesis as the ultimate salvage procedure. Surgical approaches to a variety of wrist arthropathic disorders that attempt to preserve some degree of motion have included proximal row carpectomy, four-corner fusion with and without scaphoid excision, radiolunate arthrodesis, radioscapholunate arthrodesis, and lunocapitate arthrodesis.

∗ This adapted chapter has been previously published in Fractures and Injuries of the Distal Radius and Carpus by David J. Slutsky and A. Lee Osterman.

Motion-sparing surgical procedures require healthy articular cartilage at the site of preserved motion. For proximal row carpectomy, a healthy capitate head and lunate fossa are required; for a four-corner fusion, the lunate and its fossa of the radius must have a healthy articular surface. Radiolunate and radioscapholunate arthrodesis require a healthy midcarpal joint and can provide stability but result in a significantly limited arc of motion with a moderately high failure rate because the scaphoid acts as a strut between the proximal and distal carpal rows.

Biomechanical studies have demonstrated the effect on the midcarpal joint of preserving versus osteotomizing the scaphoid, with osteotomy significantly increasing the degree of allowable motion through the midcarpal joint. When both the lunate and the scaphoid fossae are arthritic but midcarpal articulation of the capitate in its lunate and scaphoid fossae remains healthy, it is logical to attempt to preserve and use the midcarpal joint to retain motion while eliminating pain through arthrodesis of the arthritic radiocarpal surfaces.

In this chapter, we describe a step-by-step technique of using a tensioned, flexible plating system (Small Bone Innovations, Morrisville, Pennsylvania) to perform a s caphoid h emi-resection and recessed a rthrodesis of the r adio c arpal joint (SHARC procedure). The technique is supported by review of our 2- to 8-year clinical outcomes of the SHARC procedure.

The SHARC procedure allows the capitate to move within its midcarpal joint as a “universal” joint. The ideal candidate is a patient with radiocarpal arthritis and a healthy midcarpal articulation. Contraindications to performing the procedure are active local infection, systemic disease, midcarpal arthrosis, and a patient that is unwilling to comply with postoperative instructions and rehabilitation protocols.

PREOPERATIVE PLANNING

Patients with radiocarpal arthritis should have a thorough history, physical examination, and radiographic assessment. These patients usually have an extended history of wrist-related complaints with or without previous wrist trauma. These complaints can include pain, loss of strength, and considerable restriction of motion. Radiographic analysis (including CT scans if needed) should demonstrate a smooth, regular contour of the capitate with maintenance of healthy articular cartilage of the midcarpal joint. The hamate and proximal pole of the scaphoid should have structural viability (i.e., no evidence of avascular necrosis or collapse).

SURGICAL TECHNIQUE

For this outpatient procedure, patients are positioned supine, and standard prepping and draping techniques are applied. After appropriate preoperative antibiotics have been administered, an upper-arm tourniquet is generally inflated to 250 mm Hg. The surgeries are performed with the patient under either regional axillary block anesthesia or general anesthesia. The patient’s arm is placed on the hand table in a fully pronated position. The surgeon is seated on the axilla side of the table with an assistant facing across.

A dorsal midline incision is used in all cases. The extensor retinaculum is step-cut and reflected, and the extensor tendons from the first through fifth compartments are mobilized and retracted ( Fig. 27-1 ). As an adjunct to postoperative pain relief, a posterior interosseous sensory neurectomy is performed ( Fig. 27-2 ). The radiocarpal joint capsule is incised longitudinally and elevated medially and laterally, exposing the entire distal radius, scaphoid, lunate, and midcarpal joint. The radiocarpal articulation should be assessed at this point, confirming the preoperative diagnosis of arthritic degeneration of both the radioscaphoid and radiolunate articular surfaces with preservation of a healthy articulation at the capitolunate joint ( Fig. 27-3 A and B).

Residual degenerative articular surface of the proximal lunate and scaphoid is removed with a curet, rongeur, or high-speed burr ( Fig. 27-4 A and B). Similarly, a burr is used to create a complementary recessed “cup” in the distal radial metaphysis ( Fig. 27-5 A and B). The scaphoid is next osteotomized at its waist, and the distal half of the scaphoid is sharply excised ( Fig. 27-6 ). The proximal scaphoid and lunate, with exposed raw cancellous bone along their entire proximal surfaces, are then recessed into the hollowed-out distal radius in a neutral position ( Fig. 27-7 ). Kirschner (K) wires (0.045 inch) from the wrist-fit fixation set are then inserted from dorsal distal to palmar proximal in an oblique fashion, placing at least three K wires between the scaphoid and lunate into the radius ( Fig. 27-8 ). Alternatively, the pin plates from the distal radius fixation system (TriMed, Valencia, California) may be used. In most cases, two K wires are placed in the scaphoid longitudinally and two in the lunate transversely. Three flexible conforming plates are then slid over the K wires ( Fig. 27-9 ) and held in place while the screw holes are predrilled, measured, and secured down with cortical screws, thus “tension locking” the pin plate constructs into place. The depth of the K wires is then measured, and the K wires are replaced with high-angle screws from the set ( Fig. 27-10 A–C). X-ray confirmation ensures satisfactory alignment of the recessed scapholunate arthrodesis and maintenance of the capitate within the scapholunate midcarpal fossa, now functioning as a universal joint ( Fig. 27-11 A–F).