Kienböck Disease

Abstract

Kienböck disease, described as lunatomalacia by Robert Kienböck in 1910, is avascular necrosis of the lunate unrelated to acute fracture. Kienböck disease generally impacts individuals 20 to 40 years of age with a 2:1 male-to-female predominance. Although the precise etiology is unknown, several contributing factors have been suggested, including negative ulnar variance, intraosseous pressure, wrist kinematics, lunate morphology, and variations in vascular anatomy. Patients typically present with deep pain to the dorsum of the wrist, which is aggravated by activity. Examination typically demonstrates localized swelling and tenderness over the lunate, decreased wrist range of motion, reduced grip strength, clicking, or carpal instability. Early in the disease process, radiographs may be normal. With time, a characteristic pattern of deterioration occurs, beginning with sclerosis of the lunate, followed by fragmentation, collapse, and finally arthritis. Treatment goals target improvement of pain and function. They allow for lunate protection and revascularization. Management for Kienböck disease is largely surgical, but ultimate treatment decisions should account for the patient’s age, general health, demands on the wrist, lifestyle, and goals.

Keywords

Avascular necrosis, Kienböck, lunate, lunatomalacia, osteonecrosis

Synonyms
Lunatomalacia Lunate osteomalacia or osteonecrosis Avascular necrosis of the lunate
ICD-10 Codes
M19.231	Secondary osteoarthritis, right wrist
M19.232	Secondary osteoarthritis, left wrist
M19.239	Secondary osteoarthritis, unspecified wrist
M93.1	Kienböck disease of adults
M92.219	Lunatomalacia

Definition

Kienböck disease, described as lunatomalacia by Robert Kienböck in 1910, is avascular necrosis of the lunate unrelated to acute fracture. Kienböck disease generally impacts individuals 20 to 40 years of age with a 2:1 male-to-female predominance. Historically, the disease was reported most often in the dominant hand, but there is little evidence regarding this. Pathogenesis is likely multifactorial and thought to be related to the combination of nonphysiological stress transmission across the lunate and vascular abnormalities leading to fragmentation and collapse. Although the precise etiology is unknown, several contributing factors have been suggested, including negative ulnar variance, intraosseous pressure, wrist kinematics, lunate morphology, and variations in vascular anatomy.

It is thought that increased mechanical stress on the lunate may be a key factor leading to advancement of the disease. Kienböck disease was traditionally thought of as an occupational disease due to hand vibration or repeated microtrauma in early case reports of manual laborers; however, a specific causal link has yet to be established. Several studies have found possible correlation between Kienböck disease and negative ulnar variance, in which the ulna is shorter than the radius. This variance may increase shear stress to the lunate. However, the precise role of ulnar variance is still uncertain.

As the term “avascular necrosis” implies, interruption of the blood supply to the lunate is undoubtedly a part of the process. There are several described patterns of arterial supply and intraosseous branching to the lunate. It is theorized that a lunate supplied by a single vessel or with limited intraosseous branching may be at increased risk for osteonecrosis. As arterial obstruction and emboli are rare, another theory suggests impaired venous outflow with increased intraosseous pressure may play a prominent role.

Several morphologic factors of the wrist have been found in association with Kienböck disease, including lunate size, morphology, cortical thickness, and the relative inclination and position of surrounding bones. These factors are thought to essentially increase loading to the radial aspect of the lunate. Although more rare, systemic conditions such as sickle cell disease, cerebral palsy, kidney disease, chronic systemic corticosteroid use, and septic emboli may play a role in development of Kienböck disease.

Symptoms

Patients typically present with deep pain to the dorsum of the wrist aggravated by activity—specifically, wrist extension and gripping. Wrist stiffness, loss of motion, and decreased grip strength are common complaints. Later in the disease process, patients describe clicking and instability. Symptoms are often present for years before a patient seeks medical attention.

Physical Examination

Examination typically demonstrates localized swelling and tenderness over the lunate. As the disease progresses with peri-lunate synovitis, this may lead to decreased wrist range of motion and reduced grip strength. Range of motion is most restricted with wrist extension. Wrist rotation is relatively preserved. Later in Kienböck disease, symptoms of carpal instability and degenerative arthritis may appear. This includes clicking and crepitus along with severely restricted range of motion. When this occurs, patients may have positive testing maneuvers for scapholunate dysfunction including Watson’s test. Neurologic and vascular examination findings are normal.

Functional Limitations

Functional limitations include difficulty with heavy lifting, gripping, and activities involving the extremes of wrist motion. Many heavy laborers may be unable to perform essential occupation-specific tasks. Most notably, occupations requiring repeated wrist extension or vibration may be difficult, including forestry, construction, and mining.

Diagnostic Studies

Imaging plays a crucial role in identification and staging of Kienböck disease. Early in the disease process, radiographs may be normal. With time, a characteristic pattern of deterioration occurs, beginning with sclerosis of the lunate, followed by fragmentation, collapse, and finally arthritis ( Fig. 35.1 ). The final stage, Kienböck disease advanced collapse (KDAC), includes degenerative arthritis of the other carpal bones and joints. Findings closely resemble those of scapholunate advanced collapse.

The initial diagnostic imaging for suspected Kienböck disease includes standard minimum three-view wrist radiographs ( Fig. 35.2 ). Computed tomography (CT) can give additional information regarding the extent of osseous necrosis, trabecular disruption, coronal fractures, and fragmentation that may be missed with standard radiographs. Magnetic resonance imaging (MRI) is most useful in early Kienböck disease when CT and radiographs are negative. Specifically, MRI can detect subchondral collapse and evaluate integrity of the cartilage, which may alter surgical management ( Fig. 35.3 ).

Imaging classification systems, along with clinical and arthroscopic findings, can help guide treatment. The modified Lichtman four-stage classification system is the most widely used today. It utilizes radiographic osseous morphologic characteristics to delineate stages within the natural history of Kienböck disease ( Table 35.1 ; Fig. 35.4 ). However, basic radiographic findings do not always correlate with degree of symptoms, which contributes to the difficulty in assessing the natural history of this condition. In recent years, an MRI-based classification system has been developed that allows for evaluation of bone marrow perfusion and viability. There is also an arthroscopic classification based on the amount of non-functional articular surface of the lunate.

Differential Diagnosis