Kienböck’s Disease

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INTRODUCTION

Kienböck’s disease, or lunatomalacia, is an avascular osteonecrosis of the lunate that causes progressive collapse of the bone followed by progressive collapse of the carpus and secondary osteoarthritis. The cause and natural history are unknown, but it is known to be a slowly progressive disorder. Several extrinsic and intrinsic factors have been investigated regarding their role in the etiology of the bone necrosis. Several stages of Kienböck’s disease are well recognized, leading to various treatments. Little is known about the effectiveness of the treatments, mainly because Kienböck’s disease is not common and a long follow-up is absolutely necessary to evaluate the outcome.

EVALUATION

Kienböck’s disease most often occurs in young adults (between 20 and 45 years), but it can also occur in children and older age groups. It is more common in men. Kienböck’s disease is usually unilateral and isolated. A history of trauma is often reported by affected patient, although it is generally a minor trauma, or the wrist has been subjected to repetitive trauma. The disease is slowly progressive, and the symptoms and signs are nonspecific. Patients complain of dorsal wrist pain, weakness, and restricted motion. On physical examination, the dorsal tenderness is obvious and often well localized over the dorsal side of the lunate. In more advanced cases, swelling due to the synovitis, loss of wrist motion, and decreased grip strength due to an underlying degenerative arthritis are noted. Early signs of synovitis include a restricted anteroposterior drawer test of the wrist (pseudostability) as well as the obliteration of the anatomic snuffbox ( Fig. 55-1 ). In the anteroposterior drawer test, the examiner grasps with one hand the forearm of the patient, just proximal to the wrist joint, and with the other hand grasps the patient’s hand just distal to the wrist joint. Then the patient’s hand is moved in a dorsopalmar direction. Normally, some translation is possible, but not when there is synovitis (pseudostability).

Occasionally, lunate collapse is detected on a routine wrist x-ray in an otherwise asymptomatic patient.

The diagnosis and staging of Kienböck’s disease are based on x-ray findings. In the early stages, the plain radiographs may be normal, but the diagnosis can be suspected based on an abnormal bone scan or magnetic resonance imaging (MRI). Computed tomography (CT) scanning may reveal a lunate fracture. In a later stage, sclerosis of the lunate and collapse are observed.

The pathogenesis of the wrist pain in Kienböck’s disease is not always apparent. The bone necrosis in the strict sense can be a source of dorsal wrist pain. Radial-side wrist pain, in the presence of a positive Watson scaphoid shift test result, is indicative of rotatory subluxation of the scaphoid. Generalized wrist pain and swelling are indicative of osteoarthritis.

ETIOLOGY

The blood supply of the lunate is probably the key factor in the pathogenesis of the disorder. The extraosseous anatomy and intraosseous vascular anatomy have been well studied. The carpal bones with type 1 vascularity are “at risk.” These are carpal bones that are mostly supplied by only one vessel without additional anastomoses; hence occlusion of this vessel would seemingly lead to necrosis. According to Gelberman and associates, all scaphoids and capitates and 8% to 20% of the lunates have this vascular pattern. Besides arterial insufficiency, venous stasis has also been suggested as a possible cause of bone necrosis. Extrinsic factors such as fractures and repetitive minor trauma can damage the intraosseous blood supply leading to osteonecrosis. The presence of a fracture, however, can also be a consequence rather than the cause of the necrosis.

Hulten noted an association between Kienböck’s disease and a minor ulnar variance. The importance of this finding in the etiology of Kienböck’s disease, however, has been recently cast into doubt. Several authors have found a change in the ulnar variance with age, gender, and position of the wrist as well as osteoarthritis due to Kienböck’s disease. Morphologic factors may also play a role. In our series, we found that a negative ulnar variance was not predisposing to Kienböck’s disease. However, when we compared the contralateral wrist with an age- and sex-matched control group, we found that in patients with Kienböck’s disease, the lunates were smaller and had more of a radial tilt than those of the control group and that the radial slope of the distal radius was less than in the control group.

MANAGEMENT

A thorough evaluation of the involved wrist is necessary before instituting treatment. First, the stage of the disease must be determined, followed by an evaluation of the biomechanical effects of the collapsed lunate on the carpus. The biologic effects of the diseased bone, which may or may not be associated with synovitis and/or fibrosis resulting in wrist stiffness, and their effects on the patient’s disability have important implications with regard to future management. Finally, the presence or absence of osteoarthritis may be a distinguishing factor between repair/reconstruction and a salvage procedure.

Lichtman and associates classified Kienböck’s disease into four stages:

Stage I.

The radiographic appearance of the lunate is normal, and bone scintigraphy is positive.
Stage II.

The lunate exhibits increased density, but its size and shape are normal.
Stage III.

The lunate has collapsed, allowing the capitate to migrate proximally. In stage IIIA, the scaphoid maintains a normal position relative to the rest of the carpus; in stage IIIB, there is rotatory subluxation leading to a scaphoid “ring” sign.
Stage IV.

Secondary osteoarthritis of the radiocarpal joint is present.

Treatment options include both conservative and operative methods. As a rule, surgical treatment is preferred because it generally leads to a quicker improvement of the symptoms and a better outcome. Many operative treatments have been suggested for the various stages of Kienböck’s disease, which can be grouped into three broad categories:

1.

Direct revascularization by vessel implantation or a vascularized bone graft (VBG) (stages I and II).
2.

Joint decompression. This not only relieves the symptoms but allows spontaneous revascularization of the lunate while diminishing the compressive forces acting on it (stages I, II, and IIIA). This can be done by leveling the distal radioulnar joint (DRUJ), by intracarpal arthrodesis, or by capitate shortening. Restoring the normal carpal height with either a scaphotrapeziotrapezoid (STT) or a scaphocapitate arthrodesis is a key element in preventing osteoarthritis.
3.

Salvage procedures for pain relief. These include wrist denervation (resection), arthroplasty, and arthrodesis (stages IIIB and IV).

Nonoperative Treatment

Nonoperative treatment has its proponents. The foundation for this approach lies in the observation that spontaneous regression of the signs in early Kienböck’s disease has been observed. Cases of asymptomatic patients with longstanding radiographic evidence of Kienböck’s disease have also been reported. Previous reports suggest that the pain can subside within several years. Kristensen and associates reported good results after short periods of immobilization; whereas Mikkelsen and Gelineck noted poor outcomes after nonoperative treatment. The debate continues with some authors advocating a conservative approach, whereas others have observed progressive clinical and radiographic deterioration or have demonstrated better outcomes with the surgical approach. Although Kienböck’s disease is rare in children, the nonoperative approach is preferred in this group. What we and others have observed is that there is some adaptation of the carpus through remodeling rather than collapse. A wait-and-see policy or—in very painful wrists—a temporary short period of immobilization with casting or bracing can result in an asymptomatic wrist.

Revascularization by Vascularized Bone Implantation

The lunate is the keystone of the proximal carpal row. Simple resection leads to immediate and severe collapse of the carpus with subsequent osteoarthritis. The basic principles involve revascularizing the lunate (usually with temporary stabilization of the carpus to prevent collapse during the revascularization period), which preserves the integrity of the wrist, or performing an intercarpal arthrodesis on the radial or ulnar side to prevent carpal collapse by decompressing the lunate. With revascularization, the integrity of the wrist is preserved; with the arthrodesis, there is additional decompression of the lunate.

Direct revascularization, or replacement of necrotic bone by well-vascularized bone, is a logical approach to the problem ( Fig. 55-2 ). Historically, the lunate has been replaced by the pisiform bone, which is pedicled on the ulnar artery. Other authors have removed the necrotic bone by curettage, followed by cancellous bone grafting and vessel implantation such as the posterior interosseous artery. There is clear evidence that the bone grafts were revascularized by this technique. VBGs have the advantage of immediate implantation of viable bone, which simplifies matters by substituting the bone defect for a healing fracture. One does not have to wait for secondary revascularization of a cancellous bone graft, and it eliminates the period of temporary weakening that occurs with nonvascularized bone grafts. The Mayo group studied the vascularity of the distal radius. Based on anatomic studies and animal experiments, they developed the so-called 4,5 extensor compartment vascularized bone graft. In their clinical series of 26 patients, Mayo researchers reported pain relief in 92% of patients, a significant improvement in grip strength, and maintenance of carpal height in 77%. We have adopted this technique for the treatment of early Kienböck’s disease with a painful but still mobile wrist.

Indications

We found that stages I and II Kienböck’s disease are good indications for a VBG, provided that the lunate is not fractured.

Contraindications

Smoking is a general contraindication to VBG. Moreover, this procedure is not suitable in older patients. We limit this procedure to patients younger than 40 years of age.

Surgical Technique of the Dorsal VBG

A straight skin incision is made over the dorsal wrist from the third metacarpal base to the distal forearm. The fifth dorsal extensor compartment is exposed and incised. The extensor tendons are retracted radially. The fifth extensor compartment artery (ECA), which originates from the dorsal branch of the anterior interosseous artery, is identified (see Fig. 55-2 A). The fourth extensor compartment artery originates from the fifth ECA or anterior interosseous artery and supplies nutrient branches to the dorsal aspect of the radius within the fourth extensor compartment. A bone graft proximal to the radiocarpal joint and overlying the fourth ECA including the nutrient vessels is outlined. The lunate is then exposed, and the necrotic part is removed through a dorsal cortical window. The anterior interosseous artery is ligated proximal to the fourth and fifth ECA (see Fig. 55-2 B). The vascularized bone is now mobile and is placed into the gap in the lunate. In patients with stage IIIA Kienböck’s disease an STT fusion has to be performed at the same time to control the rotatory subluxation of the scaphoid and to prevent carpal collapse ( Fig. 55-3 ). Postoperatively, the patients are immobilized in a below-elbow cast for 6 weeks.

Outcomes

We treated eight patients with Kienböck’s disease by harvesting a pedicled, vascularized bone segment from the dorsal aspect of the distal radius and grafting it into the lunate. The procedure’s effect on carpal collapse and clinical outcome was assessed at a mean follow-up of 29 months (range 13 to 42). Postoperatively, patients had considerably less pain (45% during activity and 74% at rest). Postoperative mean range of movement was 65% of the unaffected side (range 43% to 76%, standard deviation 13). Three patients had an excellent result, three had good results, one had a fair result, and one was unsatisfied (modified Mayo wrist score). The mean postoperative DASH (disabilities of the arm, shoulder, and hand) score was 29.8 (compared with 40.0 preoperatively). This limited series demonstrates that a vascularized bone graft is effective in treating Kienböck’s disease, which echoes the experience of the Mayo group.

Leveling Procedures of the DRUJ: Radial Shortening or Ulnar Lengthening

Leveling the ulna to the radius by shortening the radius or lengthening the ulna is based on Hulten’s finding that Kienböck’s disease was more common in negative ulnar variance wrists. Despite the fact that several authors have questioned this finding, good clinical results have been reported with these leveling procedures. The basic mechanism seems to be an unloading of the lunate and prevention of further collapse. Proponents of more sophisticated procedures, including lateral closing and opening wedge osteotomies and medial closing wedge osteotomies of the radius, claim that the osteotomy changes the morphologic aspects of the distal radius. Some authors believe that the biologic effect of the osteotomy is responsible for the pain relief. Based on this, Illarramendi and associates proposed a pure fenestration of the distal radius and ulna rather than a change in length or orientation. Most classic papers and handbooks still recommend an osteotomy for stages I and II, and some even for stage III, provided there is a negative ulnar variance. The morphology of the sigmoid notch and the ulnar head must be evaluated before any joint-leveling procedure. Morphologic studies of the DRUJ have distinguished three different types of sigmoid notch of the radius that create the potential for DRUJ incongruity or impingement following a change in the length of one of the forearm bones ( Fig. 55-4 A and B). In these cases, some other type of decompressive procedure should be considered ( Fig. 55-5 ).