Proximal Row Carpectomy for Scaphoid Nonunion Advanced Collapse Wrist

Fig. 26.1

a and b posteroanterior and lateral preoperative radiographs. There is evidence of radioscaphoid arthrosis. (Published with kind permission of © Olukemi Fajolu and Charles Day, 2015. All Rights Reserved)

Fig. 26.2

a Coronal T2-weighted and b coronal T1-weighted MRI scans revealing decreased signal within the proximal pole of the scaphoid concerning for avascular necrosis. (Published with kind permission of © Olukemi Fajolu and Charles Day, 2015. All Rights Reserved)

Fig. 26.3

Sagittal T1-weighted MRI scan revealing the extended posture of the lunate consistent with a DISI deformity. (Published with kind permission of © Olukemi Fajolu and Charles Day, 2015. All Rights Reserved)

Diagnosis

The patient was diagnosed with scaphoid nonunion advanced collapse (SNAC) given findings on both X-ray and MRI. A SNAC wrist pattern of arthritis develops from a scaphoid nonunion that goes untreated. Given the blood supply of the scaphoid, which is predominantly retrograde, proximal pole fractures are more at risk for developing a nonunion. Scaphoid fractures that go untreated and result in nonunions are at risk for developing a DISI (dorsal intercalated segment instability) deformity as well as a SNAC wrist. [1, 2] In stage I of SNAC, the arthritis is localized to the distal scaphoid and the radial styloid. In stage II, this progresses to the radioscaphoid joint. Stage III involves the midcarpal joint, specifically the scaphocapitate and capitolunate joints. Stage IV involves pancarpal arthritis. As a general rule, the proximal lunate is often spared, as is the lunate fossa. This patient was diagnosed with SNAC stage II .

Management Options

In general, treatment for SNAC wrist is largely determined based on the stage of the condition. For stage I SNAC wrist, treatment options include excision of distal scaphoid and radial styloidectomy with possible fixation of scaphoid nonunion with bone graft . A distal scaphoid resection, also known as the Malerich procedure [3], is a possible procedure for this early stage of SNAC because it allows the patient to mobilize quickly after surgery, does not require any bony healing, and allows for subsequent surgeries, should the patient’s arthritis progress. For stage II SNAC wrist, options include salvage procedures such as a PRC, 4-corner arthrodesis , and total wrist arthrodesis. For stage III SNAC wrist, options include 4-corner fusion as well as total wrist arthrodesis and total wrist arthroplasty .

Management Chosen

Proximal row carpectomy (PRC) was described in 1944 by Stamm [4]. Among the salvage procedures, PRCs and 4-corner fusions are the most motion-preserving operations. When comparing a PRC to a 4-corner fusion, however, findings in the literature have been varied. While there are some studies that that have shown more motion preservation after a PRC. There are others that suggest they have similar ROM outcomes [5–7]. In a proximal row carpectomy, the scaphoid, lunate, and triquetrum are excised, and the capitate comes to articulate with the lunate fossa of the distal radius. The lunate fossa of the distal radius and the lunate more closely match in terms of their radii of curvature. The capitate, however, has a slightly different radius of curvature, and thus, a PRC leaves a translational component to the new articulation [8].

One of the contraindications of a PRC is significant cartilage wear in the head of the capitate. It is also ill-advised in patients with inflammatory arthritis or collagen disorders. Given the absence of cartilage wear on the capitate in our patient, the decision was made to proceed with a PRC. In addition, the patient’s smoking history presents potential difficulty for him to heal from an arthrodesis procedure. We discussed the risks, benefits, and alternatives of the procedure, and the patient underwent a PRC for his SNAC wrist without event.

Surgical Technique

In a proximal row carpectomy , these are typically approached from either a transverse or longitudinal dorsal incision. Our preference is to use a longitudinal incision made over the dorsum of the wrist ulnar to Lister’s tubercle. The extensor retinaculum is then incised over the 3 rd dorsal extensor compartment. The capsulotomy may be performed in various ways. It is our preference to perform the capsulotomy with an inverted-T, reflecting the capsule off the carpus. A posterior interosseous neurectomy is typically performed to help decrease postoperative wrist pain. If significant synovitis exists upon inspection of the joint, a synovectomy is typically performed, which was the case in our patient .

The head of the capitate as well as the lunate fossa should be inspected once the midcarpal and radiocarpal joints are exposed, to ensure there is no cartilage wear on these surfaces. We prefer to provide longitudinal traction in order to inspect these surfaces prior to proceeding with a PRC. If there is significant arthritis at these surfaces, an alternative procedure should be considered. As a general rule, we consent patients for all possible procedures, in the event that the arthritis is more extensive than initially thought, based on the preoperative MRI images. The lunate, triquetrum, scaphoid nonunion site, and all associated osteophytes should be removed in their entirety (Fig. 26.4). It is our typical fashion to do this with a combination of sharp dissection with a Beaver blade as well as a rongeur. Fluoroscopy is used to confirm the proper identification of the carpal bones prior to excision. It is also used to confirm complete excision of the carpal bones at the end of the procedure (Fig. 26.5). Of note, it is important when performing a PRC that the radioscaphocapitate (RSC) ligament, which runs from the distal–volar lip of the radius to the capitate, be preserved, as it functions to keep the capitate reduced in the lunate fossa, preventing ulnar translation of the carpus. Particular attention to this detail is most important when performing a radial styloidectomy , which is often done if there is carpal impingement on the radial styloid .