Arthroscopic Proximal Row Carpectomy

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CHAPTER 30 Arthroscopic Proximal Row Carpectomy

Proximal row carpectomy (PRC) is a reliable alternative to arthrodesis in the treatment of wrist osteoarthritis. PRC is a motion-preserving salvage procedure that involves excision of the scaphoid, lunate, and triquetrum and converts the complex link joint of the wrist into a simple hinge.¹ The procedure has faced considerable criticism in regard to alteration of the normal anatomy of the wrist joint, impairment of strength and motion, improper redistribution of joint loading, subsequent radiocapitate arthritis, and an unpredictable outcome.² Conversely, many investigators have documented satisfactory motion preservation, maintained grip strength, pain relief, and patient satisfaction. Several medium- and long-term follow-up studies have demonstrated that PRC is a reliable procedure with outcomes comparable to those of other reconstructive and salvage procedures of the wrist.³^–¹⁷

ANATOMY

The wrist joint allows complicated interactions among an array of anatomic structures, each playing a role in radiocarpal stability and mobility. A host of factors contribute to the precise mechanism of wrist function, and traumatic disruption of any link in the anatomic chain alters the carpal mechanics, leading to a predictable and progressive degeneration of the joint. Scaphoid pathology is often primarily responsible for the development of wrist arthritis. As articular contact area decreases, load distribution becomes irregular, and shearing occurs.

The proximal row of carpal bones operates as an intercalated segment between the distal radius and the distal carpal row. Proximal row intercarpal ligament disruption leads to wrist instability. Injuries to the scapholunate interosseous ligament and the extrinsic ligamentous complex allow the lunate to extend, creating dorsal intercalated segment instability.¹⁸ The resultant palmar flexion of the scaphoid alters load distribution across the radioscaphoid articulation, increasing contact pressures and eventually leading to degenerative changes.¹⁹ The sequential progression of arthritis that ensues is referred to as scapholunate advanced collapse (SLAC) wrist.²⁰

Stage I SLAC wrist involves degeneration between the distal pole of the scaphoid and the radial styloid. In stage II, joint degeneration includes the scaphoid’s proximal pole and the entire scaphoid fossa. In the third stage, the capitate drifts proximally between the scaphoid and lunate, and the capitolunate articulation degenerates.

Another form of scaphoid pathology associated with wrist arthritis is that which results from nonunion or malunion after a scaphoid fracture. This arthritic condition also follows a predictable pattern of progression, known as scaphoid nonunion advanced collapse (SNAC).²¹ In stage I, incongruity of the distal radioscaphoid articulation leads to degenerative changes that compromise the scaphoid’s ability to stabilize the carpal rows. Stage II involves arthrosis of the scaphocapitate articulation. As wrist stability deteriorates in stage III, the capitate migrates proximally, and arthrosis between the capitate head and scapholunate complex results. The radiolunate and proximal scaphoid pole articulations are typically spared even in advanced disease.

PATIENT EVALUATION

History and Physical Examination

Primary osteoarthritis of the wrist is uncommon, because most arthritic conditions of the radiocarpal joint are post-traumatic in nature. The primary diagnoses most often are SLAC wrist occurring after a scapholunate ligament injury and SNAC wrist occurring after a scaphoid nonunion or as a sequela of an intra-articular distal radius fracture. Patients may also present with a remote history of an apparent “wrist sprain” that was neglected.

Middle-aged men, notably laborers, make up much of this patient population. Patients present with a history of a prior in jury most likely incurred by a fall onto an outstretched hand or a previous wrist surgery. Although the SLAC wrist is not always symptomatic, the patient typically complains of decreased grip and pinch strength and of activity-related pain, particularly wrist extension and radial deviation.

Physical examination may reveal dorsoradial swelling and tenderness to palpation over the carpus and radial scaphoid articulation, especially in patients with SLAC or SNAC wrist arthrosis. Motion is often diminished and painful, exhibiting considerable crepitus in passive and active ranges.

Physical examination may be facilitated by employing Watson’s standard approach to the examination of radial-sided wrist pain.²² The first maneuver assesses the articular–nonarticular (ANA) junction as the wrist is ulnarly deviated and the junction between the articular and nonarticular cartilage is palpated. Second, the scaphotrapeziotrapezoid (STT) joint is palpated by following the second metacarpal proximally until a space is reached, denoting the STT joint. Third, the dorsal wrist syndrome is ruled out by palpating between the second and fourth dorsal compartments of the wrist. A fourth test is the Watson scaphoid shift, which is performed by attempting to push the scaphoid dorsally from its volar side while passively radially deviating the wrist. A positive test elicits wrist pain as a result of scapholunate injury or ligamentous laxity. The fifth examination maneuver is the finger extension test, in which the wrist is flexed and the fingers are extended against resistance; increased loading of the radiocarpal joint and extensor tendon pressure produce pain.

Diagnostic Imaging

Standard radiographic imaging is all that is necessary to diagnose post-traumatic arthrosis of the wrist. Posteroanterior, lateral, and oblique views of the radiocarpal joint in this patient population reveal joint space narrowing, subchondral sclerosis, and cyst formation in the carpal bones and distal radius.

TREATMENT

Indications and Contraindications

The indications for the standard open PRC are also those that are applied to the arthroscopic technique. They include degenerative conditions of the proximal carpal row, such as SLAC, SNAC, chronic perilunate dislocation, Preiser’s disease, and Kienböck’s disease. One indication for PRC is complex fracture dislocation of the wrist.¹⁴ The rationale cited by the authors of this 2005 case series¹⁴ was to avoid the disadvantages of arthrodesis while anticipating the likely post-traumatic arthrosis in this patient population. Failed carpal implants, cerebral palsy and spasticity, and reimplantation have also been described as indications for PRC, although we do not recommend the latter groups of patients for an arthroscopic technique.²³

The relative contraindications to PRC are multicystic carpal disease, preexisting ulnar translocation of the carpus, and degenerative changes of the lunate fossa or capitate head. A 2007 study investigated a method to salvage a PRC for patients with degenerative changes of the head of the capitate. Tang and Imbriglia performed osteochondral resurfacing of the capitate in eight patients undergoing PRC who had a grade II to IV (modified Outerbridge scale) area of capitate chondrosis less than 10 mm in diameter.²⁴ The results with osteochondral resurfacing compared favorably with published results of conventional PRC in terms of pain relief, employment status, range of motion, and grip strength. Culp and associates⁴ and Ferlic and colleagues²⁵ did not recommend PRC for patients with inflammatory arthropathy because of its high failure rate.

Therapeutic Options

The biomechanical literature has focused on compensatory radiocarpal loading and kinematics after PRC. Blankenhorn and coworkers performed a cadaveric study using computed tomography to assess wrist motion before and after PRC.²⁶ Their results showed that wrist range of motion after PRC was sufficient for activities of daily living. Flexion and extension motion at the radiocarpal joint after PRC was greater than motion at the radiocarpal and midcarpal joints of the intact wrist, whereas overall wrist motion decreased. After PRC, the normal rotational motion of the capitate head (in the intact wrist midcarpal joint) was altered to a combination of rotation and translation.

More contemporary reports have included Disabilities of the Arm, Shoulder, and Hand (DASH) scores as a measurement of upper extremity disability after PRC. Whereas several Scandinavian studies ¹⁷^,²⁷^–³⁰ with variable follow-up times published DASH scores ranging from 28 to 36, DiDonna and associates reported an average DASH score of 9 in their study of 22 wrists after a minimum follow-up of 10 years.¹²

Cohen and Kozin published their results for a prospective cohort of similar patient groups with wrist osteoarthritis treated with scaphoid excision and four-corner fusion or PRC.⁹ Follow-up examination revealed no significant difference in the flexion-extension arc, ulnar deviation, or grip strength between the groups. The investigators also reported pain relief and patient satisfaction to be similar.

Based on combined outcomes from the larger series in the literature, PRC results in approximately 60% of the average flexion-extension arc and 71% of the grip strength of the contralateral wrist.⁴^,⁷^–⁹^,³¹^–³⁶ The degree of patient satisfaction is high, ranging from 80% to 100%,⁷^–⁹^,¹¹^,¹³^,³¹^–⁴⁰ and failure rates tend to be low, ranging from 0% to 20%.⁴^,³¹^,³²^,³⁴^,³⁸ One criticism of PRC is that it causes radiocapitate arthrosis. DiDonna and colleagues observed degeneration of the radiocapitate articulation in 14 of 17 wrists during an average follow-up time of 14 years. Despite the degree of radiographic degenerative changes, there was no significant association between the arthrosis and wrist pain, range of motion, work restrictions, or patient satisfaction.¹²

Arthroscopy has become an increasingly valuable tool in the treatment of wrist pathology. The breadth of treatment options in the wrist surgeon’s armamentarium continues to grow, as do advances in the arthroscopic equipment available. The pathologic conditions of the wrist that the arthroscopist is capable of treating include triangular fibrocartilage complex tears, distal radius and carpal fractures, cartilage injuries, and bone resections. There is scant literature available discussing arthroscopic PRC. Although there are no long-term follow-up studies, the short-term studies have described promising results.⁵^,⁴¹^–⁴⁴

Conservative Management

Nonoperative treatment may begin with activity modification and non-steroidal anti-inflammatory medication. Splinting of the wrist or steroid injections may be used to provide the patient with symptomatic relief, particularly in sedentary and low-demand situations. However, patients are counseled on the predictable course of degeneration in their particular form of wrist arthritis. Although stage I SLAC or SNAC conditions and early radiocarpal degeneration may respond to these measures, a staged approach to treatment is based on the extent of disease, and a late presentation may preclude relief from conservative measures.

Arthroscopic Technique

The patient is placed in the supine position, with the affected upper extremity on a radiolucent hand table. Operative time is usually less than 2 hours, and regional or general anesthesia is adequate for this procedure. A well-padded tourniquet is wrapped around the upper arm, and the wrist is suspended in a traction tower with 10 to 15 pounds applied (Fig. 30-1). The tourniquet is inflated, but additional exsanguination is unnecessary. After distraction is introduced, the dorsal aspect of the wrist is palpated for landmarks, and the portals are made. The 3-4 portal is routinely used as the primary viewing portal.

FIGURE 30-1 Standard traction tower with finger traps. An 18-gauge needle in the 6-U portal placed to gravity drainage serves as outflow.

(From Culp RW, Osterman AL, Talsania JS. Arthroscopic proximal row carpectomy. Tech Hand Up Extrem Soc. 1997;2:116-119.)

To perform an arthroscopic PRC, the required instruments include a traction tower, a 2.7-mm arthroscope, a hook probe, a 2.9-mm shaver or radiofrequency tool, a 4.0-mm burr, small osteotomes, pituitary rongeurs, and image intensification equipment.

The 2.7-mm arthroscope is introduced after the radiocarpal joint is insufflated with saline solution. A 6-R outflow portal is created under direct visualization at the prestyloid recess. Constant intra-articular pressure and flow are maintained with a mechanical pump. The joint is inspected in a routine fashion, with particular attention directed to the lunate fossa of the distal radius. The volar extrinsic ligaments are identified and preserved throughout the procedure—particularly the radioscaphocapitate, because it plays an essential role in stabilizing the new joint and preventing volar dislocation and ulnar translocation of the distal carpal row. The ulnar extrinsic ligaments and triangular fibrocartilage complex are identified as the arthroscope is directed ulnarly.

To assess the integrity of the proximal capitate surface, the midcarpal joint is visualized (Fig. 30-2). If the quality of this cartilaginous surface is questionable, we proceed to an alternative procedure (i.e., four-corner fusion, capitolunate arthrodesis, PRC with interpositional arthroplasty, or wrist arthrodesis). Visualization of the midcarpal joint is performed by establishing a radial midcarpal portal. This location is determined by measuring approximately 1 cm distal to the 3-4 portal.

FIGURE 30-2 A healthy-appearing proximal capitate is seen through the midcarpal portal.

(From Culp RW, Osterman AL, Talsania JS. Arthroscopic proximal row carpectomy. Tech Hand Up Extrem Soc. 1997;2:116-119.)

After the surgeon is satisfied with the status of the cartilaginous surfaces of the proximal capitate and lunate fossa, the first step in performing the PRC is to remove the scapholunate and lunatotriquetral ligaments with a shaver or radiofrequency probe. This step is carried out through the 4-5 portal or the 6-R portal, or both. This is followed by removal of the core of the lunate with a burr (Fig. 30-3). Care is taken not to damage the proximal capitate or lunate fossa, which is accomplished by leaving behind an eggshell rim of the lunate. This remainder of the lunate is then morcellized with a pituitary rongeur under direct vision or image intensification.

FIGURE 30-3 Large burr removes the center of the lunate, with care taken not to destroy the proximal capitate or the lunate fossa of the radius.

(From Culp RW, Osterman AL, Talsania JS. Arthroscopic proximal row carpectomy. Tech Hand Up Extrem Soc. 1997;2:116-119.)

The next step is fragmentation of the scaphoid and triquetrum with an osteotome and burr under image intensification and removal of the fragments in a piecemeal fashion with a pituitary rongeur while working through the 3-4 or 4-5 portal (Figs. 30-4 and 30-5). The surgeon can ensure easy removal and greater protection of the articular cartilage by first coring out and fragmenting these carpal bones.

FIGURE 30-4 An osteotome used with x-ray guidance to remove part of the scaphoid and triquetrum.

(From Culp RW, Osterman AL, Talsania JS. Arthroscopic proximal row carpectomy. Tech Hand Up Extrem Soc. 1997;2: 116-119.)

FIGURE 30-5 A pituitary rongeur is used with x-ray guidance to remove the fractionated scaphoid. This procedure can be performed with the wrist suspended in the traction tower on the radiolucent hand table.

(From Culp RW, Osterman AL, Talsania JS. Arthroscopic proximal row carpectomy. Tech Hand Up Extrem Soc. 1997;2:116-119.)

After the entirety of the proximal carpal row has been removed, the wrist is examined under image intensification (Fig. 30-6). Special attention is paid to the radial styloid area to be sure there is no impingement against the trapezium. Some surgeons recommend a moderate styloidectomy. Although we rarely carry out this aspect of the procedure, it can be done quite easily with the aid of the image intensifier.