CHAPTER SYNOPSIS:
Posttraumatic radiocarpal arthritis can develop even with mild intraarticular incongruity. If symptoms are severe enough, surgical intervention can offer significant relief. The fusion of the radius to the scaphoid and lunate results in only moderate loss of motion while providing potentially significant pain relief. Although this procedure can have a high complication rate, attention to details and adherence to basic principles often result in a satisfying outcome.
IMPORTANT POINTS:
Although total wrist fusion is the “gold standard” for surgical treatment of painful wrist arthritis, radioscapholunate (RSL) arthrodesis can adequately alleviate isolated radiocarpal arthritic pain and generally maintains approximately one third to one half normal motion.
The midcarpal joint must be free of arthritis for this procedure to be successful.
Distal radioulnar joint arthritis and ulnar abutment need to be addressed separately.
Be aware of risk of nonunion and hardware-related complications.
Excision of distal pole of scaphoid and of triquetrum may improve postoperative range of motion.
Total wrist arthrodesis is a reliable salvage procedure if unsatisfactory pain relief is obtained with RSL arthrodesis.
CLINICAL/SURGICAL PEARLS:
Positive response to radiocarpal injection may help predict surgical outcome.
As with all arthrodesis procedures, proper bone preparation is a must. Subchondral bone should be removed to expose cancellous bone on all fusion surfaces. Voids in this interface should be filled with bone graft. Autologous bone graft is considered the gold standard, but allograft may be substituted.
Removal of the distal pole of the scaphoid decreases the lever arm at the arthrodesis site and may improve fusion rates.
Maintain neutral alignment of the lunate and scaphoid to maximize range of motion.
HISTORY/INTRODUCTION
Articular incongruity following distal radius fracture is a significant risk factor for the development of radiocarpal arthritis. Knirk and Jupiter noted that any radiographic stepoff resulted in a 91% incidence of radiographic degenerative joint disease. Bradway, Amadio, and Cooney ; Ferandez and Geissler ; and Missakian, Cooney, and Amadio all noted that stepoffs of 2 mm or more were associated with a high risk for the development of posttraumatic arthritis. Symptoms, however, do not always correlate with radiographic findings, and Trumble and colleagues have demonstrated in a sheep knee model that a 1-mm intraarticular stepoff can remodel. Therefore, mild intraarticular incongruity does not guarantee the development of arthritis. However, other reports emphasize the relationship between posttraumatic radiographic changes and the eventual development of clinical pain. Therefore, the goal of treatment of distal radius fractures focuses on achieving anatomic reduction of the articular surface. Unfortunately, even with current modern fixation techniques, this is not always possible. Infrequently, articular damage not appreciated on radiographic imaging may still predispose to the development of posttraumatic arthritis.
Pain and stiffness can be related to either intraarticular or extraarticular scarring and hardware-related problems following distal radius fractures. Once solid fixation has been achieved or once there is evidence of radiographic and clinical bone healing, mobilization of the radial carpal joint should be attempted. Extensive physical therapy in conjunction with dynamic splinting often decreases stiffness in the postsurgical wrist and a gradual reduction in pain often follows. Oral steroids, antiinflammatories, and pain medications are appropriate adjuvants to aggressive therapy and help reduce posttraumatic and postsurgical stiffness of the wrist. Wrist arthroscopy can be used to lyse arthrofibrotic “spot-welds” usually after 3 to 6 months of failed progression with appropriate therapy. We have had moderate success with this approach. Additionally, sometimes either volar- or dorsal-placed hardware can be irritating and painful. We have seen cases of hardware penetrating into the radial carpal joint causing loss of motion and pain. When these problems are directly addressed, the damaged articular surfaces still may remodel. The point that needs to be emphasized here is that there are other sources of postsurgical or traumatic pain that should be thoroughly addressed before proceeding with an irreversible procedure.
The typical patient who we consider for radioscapholunate arthrodesis presents with activity-related pain and swelling. The classic presentation is that the wrist improves clinically with rest and activity modification, including splinting. We prefer for the patient to be at least 1 year out from their trauma. In some extreme situations where there is significant intraarticular incongruity, we have stretched these indications to include early arthrodesis when accompanied by disabling pain. Most cases of radiocarpal arthritis also result in at least modest loss of wrist motion. As long as the distal radioulnar joint is uninvolved, supination and pronation should be unaffected. In established cases of posttraumatic arthritis, standard radiographs should be helpful also. Classical signs of arthritis, including subchondral thickening, cyst formation, osteophyte formation, and joint narrowing, should be noted ( Figs. 4-1 and 4-2 ). Computed tomography (CT) scan can be helpful in assessing the midcarpal joint for arthritic changes or the radiocarpal joint for hardware penetration. We have not used magnetic resonance imaging (MRI) to evaluate the cartilage. In more subtle cases, we usually do a staging procedure with wrist arthroscopy for identification of articular damage prior to proceeding with fusion. This is a good opportunity to verify that the midcarpal joint is free of pathology.
When conservative steps including antiinflammatories and one or two radiocarpal steroid injections fail to maintain adequate pain relief with a confirmed diagnosis of posttraumatic radiocarpal arthritis, surgical options are discussed with the patient. Generally, the available options are total or limited wrist fusion (arthroplasty, denervation, and arthroscopy are options in certain situations). A total wrist fusion should be considered the gold standard for treatment of any wrist arthritis, and we typically offer this as one of the surgical options. Total wrist fusion has a very high fusion rate and provides excellent relief of pain at the expense of complete loss of motion. Limited radiocarpal fusion, in which the radius is fused to the scaphoid and lunate, preserves some motion through the midcarpal joint, which can be useful (especially in cases of bilateral pathology); however, there may be a slightly higher risk of incomplete pain relief and a higher complication rate including nonunions. Biomechanical studies have revealed that approximately two thirds of normal wrist motion comes from the radiocarpal joint and about one third of normal wrist motion comes from the midcarpal joint. Therefore, fusion limited to the radiocarpal joint theoretically should result in at least maintenance of one third of normal flexion/extension motion through the preserved midcarpal joint. However, postfusion motion can be improved by including limited carpal bone excision. Excision of the distal pole of the scaphoid allowed for 86% of normal wrist motion in one cadaver study, and removal of the triquetrum can result in almost normal wrist motion, as shown in a separate cadaver study (publication pending). Reported clinical results are more variable with postfusion total flexion/extension motion ranging from 47 degrees to 70 degrees. This amount of maintained motion is still satisfactory in facilitating most activities of daily living.
INDICATIONS/CONTRAINDICATIONS
The primary indications for radioscapholunate arthrodesis are recalcitrant pain localized to the radiocarpal joint with radiographic or clinical evidence of posttraumatic arthritis. Arthritis can include painful wrist inflammation even in the absence of significant radiographic changes. Pain should improve with temporary immobilization and with radiocarpal injections of lidocaine (usually including steroid). Although radiographic changes support the diagnosis, we do not believe that it is an absolute criterion for it. Degenerative changes should be noted, however—whether with radiographs, arthroscopy, or direct inspection at the time of the planned fusion—before proceeding with this irreversible procedure ( Fig. 4-3 ).
The main contraindications for this procedure include evidence of midcarpal arthritis, failure to achieve significant pain relief following a radiocarpal injection (if this is the case, pain generators other than the radiocarpal joint should be considered), and tobacco use. The use of tobacco products in our opinion unnecessarily increases the risk of nonunion in what is essentially an elective surgery.
SURGICAL TECHNIQUE
Although there are some variations in technique such as the inclusion of limited carpal excision and a variety of fixation choices, the basic principles are the same. A dorsal midline wrist incision is centered over the third or fourth extensor compartments to avoid the branches of the superficial radial nerve and the dorsal sensory branch of the ulnar nerve. After cutting sharply through the skin, a subcutaneous plane is created on top of the extensor retinaculum. The third compartment is identified and entered. The extensor pollicus longus is released and retracted out of the way. The second and fourth compartments are then opened by releasing the intercompartmental septa. In this way, the tendons are freed up to be retracted out of the way while maintaining the dorsal retinacular flap for closure. With the dorsal wrist capsule exposed, a midline capsulotomy is performed. By cutting down to bone on the distal radius and the carpal bones (be careful not to damage the cartilage on the head of the capitate), the distal radius periosteum and the wrist capsule can be lifted up as a single envelope of tissue. In this manner, the radioscapholunate articulation is exposed and at least enough of the midcarpal joint that the quality of cartilage surfaces can be evaluated ( Fig. 4-4 ). A reasonable alternative is an anatomic approach, by cutting along the radial rim of the distal radius and then along the dorsal radiocarpal ligament and the dorsal intercarpal ligament to raise a radially based flap, as described by Berger. We find that for this procedure, because the distal radial rim must be exposed, the midline incision seems to work better. Removing the dorsal rim of the distal radius can facilitate access to the radiocarpal joint. An angled curette and small rongeur can assist in the removal of cartilage and subchondral bone as the joint is hyperflexed and distracted ( Fig. 4-5 ). Typically, the use of a small burr is necessary. While burring away the subchondral bone, significant heat is produced. Copious irrigation (preferably with cold irrigation) is a must to avoid thermal necrosis of the bone. Like all fusions, proper preparation of the arthrodesis surfaces is the most important step of the procedure ( Fig. 4-6 ). Once adequate areas of cancellous bone are exposed on the articular surfaces of the scaphoid, lunate, and radius then manual compression across the radiocarpal joint is performed. If there are voids in between the bone surfaces, then bone graft needs to be added. The metaphysis of the radius can provide limited amounts of bone graft for this purpose, but care must be taken to avoid adversely affecting the distal radius fusion surface. Additional bone graft sights might include the olecranon, the proximal tibial metaphysis, and the iliac crest. Allograft cancellous bone graft is probably a reasonable alternative. Although this may seem excessive, proper bone surface contact cannot be overemphasized. Temporary fixation can be obtained with 0.045″ K-wires through the radial metaphysis into the scaphoid and lunate ( Fig. 4-7 ). Both visual and radiographic confirmation should be performed to make sure the lunate is in a neutral position. Overrotation of the lunate will result in impingement of the capitate head and subsequent loss of motion.
