78 Complications of Partial Wrist Fusion
78.1 Patient History Leading to the Specific Problem
A 55-year-old salesman presented to the office with right-dominant wrist pain. He suffers from osteoarthritic pain in multiple additional joints, including his knees, left hip, and bilateral shoulders. He is morbidly obese and ambulates with the assistance of a cane in his right symptomatic hand.
78.2 Anatomic Description of the Patient’s Current Status
His examination reveals dorsoradial wrist synovitis with motion limited to 40 degrees of flexion and 30 degrees of extension. Radiographs demonstrated stage II scapholunate advance collapse (SLAC) arthritis (▶Fig. 78.1).
After initial treatment with splinting and radiocarpal cortisone injections, the patient agreed to surgical intervention. Due to the diffuse arthritic changes on X-ray, the patient was consented for partial or total wrist fusion depending on the intraoperative findings of arthritis.
Intraoperative exploration revealed severe arthritic changes at the radioscaphoid and scaphocapitate articulations. Early cartilage changes were observed at the radiolunate joint. In an effort to preserve motion, a scaphoid and triquetrum excision and capitolunate (CL) fusion were performed.
Postoperative X-rays demonstrated healing of the capitolunate fusion, but incomplete correction of the extended posture of the lunate (▶Fig. 78.2). Rapid progressive arthritic changes were witnessed at the remaining radiolunate articulation. This became increasingly symptomatic as the patient depended on this wrist for cane-assisted ambulation. After failure of improvement, a total wrist arthrodesis was performed with success (▶Fig. 78.3).
78.3 Recommended Solution to the Problem
Operative exploration of the SLAC wrist requires surgical decision-making based on the quality of the various cartilage surfaces. The goal should be reliable pain relief while preserving motion if possible. Surgeons may select proximal row carpectomy (PRC) if the lunate fossa and capitate surfaces are well preserved. Alternatively, deficient proximal capitate cartilage in the setting of well-preserved radiolunate articulation is an indication for midcarpal wrist arthrodesis.
Fig. 78.1 Anteroposterior radiograph of the wrist demonstrating stage II scapholunate advanced collapse arthritis. Note widening of scapholunate interval and joint space narrowing of radioscaphoid articulation.
Fig. 78.2 (a) Anteroposterior and (b) lateral postoperative X-ray of the wrist after operative excision of scaphoid and triquetrum and capitolunate fusion. Note that the extended posture of the lunate is not corrected on lateral radiograph. The lunate remains in extended posture relative to the capitate.
Fig. 78.3 Anteroposterior radiograph of total wrist arthrodesis after failed midcarpal arthrodesis.
In this patient, all of these joint surfaces were suboptimal, but the radiolunate articulation was deemed least diseased and midcarpal fusion was selected. This patient had significant risk factors for failure: morbid obesity and reliance on cane-assisted ambulation. After observing cartilage wear on the native radiolunate joint, an immediate total wrist arthrodesis would have been more likely to provide durable long-term pain relief appropriate for his functional requirements.
78.3.1 Background
Total wrist arthrodesis is a reliable method of producing pain relief in patients suffering from diffuse wrist arthritis. However, range of motion is sacrificed and can limit activities of daily living. Total wrist arthroplasty (TWA) has had less widespread success as arthroplasty has experienced in other joints due to the demands specific to the wrist and associated bone and soft-tissue anatomic constraints. Variable rates of aseptic loosening and 5-year survival have led to TWA being employed primarily in elderly and other low-demand patients.
Younger, active patients with arthritic wrists often pursue a durable pain-relief procedure with preservation of range of motion. Limited wrist arthrodesis eliminates painful motion at arthritic joints, while preserving motion at uninvolved articulations. SLAC wrist often demonstrates preservation of cartilage in the radiolunate joint, enabling motion to be preserved after scaphoid excision and midcarpal fusion. Thirty to 50% of sagittal motion occurs in the midcarpal joint, with the remainder through the radiocarpal joint. Compensatory increases in range of motion at the unfused joints have been demonstrated within 1 year postoperatively.
78.3.2 Scapholunate Advance Collapse
SLAC wrist is the most common observed arthritic wrist pattern, a sequence of degenerative change based on and caused by articular alignment problems between the scaphoid, lunate, and radius. However, to date, there is no scientific evidence that scapholunate (SL) injury visualized arthroscopically without static radiographic changes inevitably leads to SLAC wrist. Although cadaver models indicate progressive rotatory subluxation of the scaphoid leads to altered contact, implying a nidus for arthritis, limited evidence indicates that reconstruction or repair of acute SL tears delays or prevents arthritis.
SLAC pattern begins at the radial styloid and scaphoid junction (stage I), progressing to include the radioscaphoid articular surface (stage II). The radioscaphoid joint is more susceptible due to its elliptical shape. As the SL interval widens, the head of the capitate migrates proximally into the widened interval, resulting in midcarpal capitate–lunate joint arthritis (stage III), with the radiolunate joint spared. The radiolunate joint is generally spared due to its uniformly spherical nature allowing cartilage loading in all positions despite changes in lunate orientation.
Midcarpal Arthrodesis with Scaphoidectomy versus Proximal Row Carpectomy
Midcarpal arthrodesis (MA) and PRC offer motion-preserving alternatives to total wrist arthrodesis. PRC is a less demanding technique with a shorter immobilization time. Good preservation of cartilage on the proximal capitate (i.e., SLAC wrist stages I and II) is considered a prerequisite for PRC, although surgeons have also employed capitate resurfacing techniques in conjunction with PRC and reported reasonable outcomes.
Treatment of stage III SLAC/SNAC wrist with MA is feasible as it does not require a preserved capitate. The procedure is technically more demanding than PRC, necessitates longer immobilization, and requires achievement of radiographic/clinical union. Range of motion is felt to be particularly limited if care is not taken to reduce the lunate into neutral posture or slight flexion when performing the arthrodesis. If the lunate is arthrodesed in extension, the fusion mass may impinge on the dorsal lip of the radius, limit extension, and cause pain. Despite these requirements, advocates cite advantages of preservation of carpal height and radiolunate congruity. With appropriate surgical technique and bone graft placement, reported failure rates and conversion to total wrist arthrodesis can be 2 to 4% at 15-year follow-up.
In the short term, outcomes are generally equal; differences in degrees of range of motion or grip strength have questionable clinical relevance. Mulford et al, in a systematic review of 52 studies, found pain relief can be achieved in 85% of patients, grip strength reaches approximately 80% of the opposite side, and conversion to total wrist arthrodesis is seen in 5% for both procedures, although the flexion–extension arc may be slightly less in MA.
Other considerations should be made when selecting the right procedure. It has been suggested that MA may be more durable in the young active laborer. DiDonna et al studied a series of PRCs and found all failures occurred in patients younger than 35 years of age. In this subset of patients, MA has been advocated. PRC has been found to have a significant increase in developing subsequent osteoarthritis on systematic review. The proximal capitate has a smaller radius of curvature than the lunate and does not demonstrate ideal congruity in the lunate fossa of the radius. MA has the advantage of preserving the native spherical radiolunate articulation. However, many authors have found minimal clinical correlation with eventual radiocapitate degeneration after PRC.
78.3.3 Alternative Midcarpal Fusions
The goal of midcarpal fusion is creating a stable arthrodesis via the CL joint and enabling wrist articulation load bearing to be assumed by the radiolunate joint. Initial reports of CL arthrodesis with K-wire fixation were unsuccessful, with nonunion rates as high as 33 to 50%. In 1984, Watson described including the hamate and triquetrum to the CL fusion mass to improve bony fusion rates. This procedure is often referenced as a four-corner fusion (4CF).
Authors began revisiting techniques when compression screw technology improved fusion rates. Goubier and Teboul had a high fusion rate in their CL arthrodesis series (12 of 13) all with improved pain. Calandruccio et al, in their series of 14 patients, had 2 patients with nonunions and 1 with persistent pain. Most recently, Gaston et al compared 16 CL arthrodesis to 18 patients who received 4CF. They found the CL arthrodesis group had similar grip strength, range of motion, and pain outcome to the 4CF group. There was decreased need for bone graft (50 vs. 100%) and the lunate was easier to reduce following triquetral excision, particularly in a type II lunate where the CL joint is not collinear. Impressively, there were no nonunions with use of the compressive screws with CL arthrodesis compared to 11% in the 4CF. Two patients in each group required conversion to total wrist arthrodesis.
As an alternative, there has also been increased interest in 3CF (fusion of the capitate, lunate, and hamate and excision of the scaphoid and triquetrum) as a means to increase range of motion but mitigate incidence of nonunion seen in CL arthrodesis. Cadaver studies show subsequent excision of the triquetrum improved wrist range of motion when converting arthrodesis from 4CF to 3CF. A small case series has demonstrated success with 3CF in 12 patients, with 1 nonunion and 2 revisions.
Persistent/Recurrent Pain after Partial Arthrodesis and Conversion to Total Wrist Arthrodesis
When limited wrist arthrodesis patients have incomplete relief or worsening pain, total wrist arthrodesis is considered the next step in the surgical algorithm. Neubrech et al examined long-term results (14.7 years) of 594 4CF with K-wire and bone graft with a 6.7% conversion rate to total wrist arthrodesis primarily due to persistent pain and nonunion, and an 11.1% complication rate requiring revision surgery. Other authors report failure of 4CF due to persistent pain occurring in up to 30% of patients.
78.4 Technique
A dorsal longitudinal wrist incision is made to expose the extensor retinaculum. The dorsal retinaculum is opened in the third compartment, releasing the extensor pollicis longus. The fourth compartment is elevated ulnar-ward and the second compartment retracted radially. The dorsal capsule is reflected generously to expose the radiocarpal and midcarpal joints. The joints are inspected, primarily with the goal of assessing the quality of the cartilage surfaces of the proximal lunate and lunate fossa of the radius. If these surfaces are free of arthritic changes, a midcarpal fusion may be pursued.
The scaphoid and triquetrum are resected completely. The intact volar wrist ligaments will be visible after complete resection of the scaphoid and should be preserved.
A rongeur is used to remove the cartilage and dense subchondral bone of the opposing surfaces of the distal concave lunate and the proximal convex capitate. After meticulous preparation of these surfaces, they are coapted in a cup/cone relationship with great care taken to reduce the lunate into neutral posture or slight volar flexion. The longitudinal axis of the capitate and lunate should be collinear in both lateral and posteroanterior projections. With the wrist flexed, a guidewire is inserted antegrade through the proximal lunate cartilage surface into the capitate (▶Fig. 78.4). Care is taken not to violate the capitohamate or carpometacarpal joints. Cancellous bone autograft may be harvested from the triquetrum and inserted into the arthrodesis site prior to screw placement. Cannulated headless compression screws are inserted and generously buried beneath the cartilage surface (▶Fig. 78.5).
With the guidewires removed, the wrist may be brought into extension. Fluoroscopy confirms position, placement, and depth of hardware as well as the lunate position and coaptation of the fusion surface (▶Fig. 78.6).
78.5 Postoperative Photographs and Critical Evaluation of Results
In the first case presented, patient selection and operative technique led to overall failure in achieving pain relief. Postoperative radiographs demonstrated inadequate reduction of the midcarpal joint prior to fixation, with a persistent extended posture of the lunate relative to the capitate (see ▶Fig. 78.2b). In a separate patient, appropriate reduction of the lunate resulted in neutral posture of the lunate relative to the capitate (▶Fig. 78.7).
78.6 Teaching Points
• SLAC wrist stage II can be treated with PRC or midcarpal fusion.
• MA may be performed with a variety of techniques, with CL fusion being the common goal of the described procedures.
• The most common symptom of clinical failure necessitating reoperation is persistent or recurrent pain.
