Lunatomalacia — also known as Kienböck's disease — is a condition in which the lunate bone loses its blood supply, leading to avascular necrosis (bone death), progressive collapse, and eventual wrist arthritis. The lunate sits in the center of the proximal row of carpal bones and plays a critical role in wrist motion. Without treatment, the condition typically worsens over time.
Kienböck's disease is one of the most important causes of central wrist pain in young adults and is strongly linked to negative ulnar variance — an anatomic variant in which the ulna is shorter than the radius. It shares some clinical overlap with wrist fracture, as early lunate changes can be subtle on X-ray and are most reliably detected on MRI. In advanced stages, carpal collapse and malalignment can resemble the pattern seen in SLAC wrist.
Causes
The exact cause of Kienböck's disease is not fully understood, but several contributing factors have been identified:
- Disrupted blood supply: The lunate has a relatively tenuous blood supply, receiving blood from only one or two small arteries in many individuals. Any disruption of this fragile supply can lead to bone ischemia and necrosis.
- Negative ulnar variance: When the ulna is shorter than the radius, increased mechanical stress is concentrated on the lunate — considered a major predisposing anatomic factor.
- Trauma: Both single significant wrist injuries and repetitive microtrauma can disrupt the lunate's blood supply or cause subtle fractures that progress to necrosis.
- Occupational and activity-related stress: Manual laborers and individuals performing repetitive forceful wrist activities — such as using jackhammers or heavy tools — appear to be at increased risk.
- Systemic conditions: Conditions affecting blood supply or bone health — including sickle cell disease, lupus, corticosteroid use, and gout — have been associated with avascular necrosis of the lunate.
- Anatomic variations: Variations in lunate shape or distal radius geometry may predispose to the condition.
- Age and gender: Kienböck's disease most commonly affects men between the ages of 20 and 40, though it can occur at any age.
Symptoms
Symptoms typically develop gradually and worsen over time as the condition progresses:
- Central wrist pain: Deep, aching pain over the dorsal (back) aspect of the wrist, particularly over the lunate. Pain is worse with activity and improves with rest.
- Swelling: Visible or palpable swelling over the back of the wrist.
- Stiffness: Decreased range of motion, particularly with wrist extension.
- Tenderness: Focal tenderness directly over the lunate on the dorsal wrist.
- Weakness: Reduced grip strength, often noticed with tasks like opening jars or lifting.
- Clicking or catching: As the lunate collapses, mechanical symptoms including clicking and a sense of instability may develop.
- Progressive worsening: Without treatment, symptoms typically worsen over months to years, eventually leading to wrist arthritis and significant functional impairment.
Diagnosis
Physical examination reveals focal tenderness over the lunate, reduced wrist motion, and diminished grip strength. X-rays are the initial imaging study — in early disease they may appear normal, but as the condition advances they show lunate sclerosis (increased density), fragmentation, and eventual collapse.
MRI is the most sensitive test for Kienböck's disease and is essential for early diagnosis. A dedicated wrist MRI can detect changes in the lunate's blood supply before any X-ray abnormality appears — decreased signal on T1-weighted images is the hallmark finding of early avascular necrosis. MRI also accurately assesses the degree of lunate collapse, cartilage integrity, and involvement of adjacent carpal bones, all of which directly determine staging and treatment. CT may be added to evaluate bone architecture in detail when surgical planning requires it.
Classification (Lichtman Stages)
Kienböck's disease is staged using the Lichtman classification, which guides treatment decisions:
- Stage I: Normal X-rays; abnormal MRI showing altered signal in the lunate consistent with decreased blood supply. The lunate maintains normal shape.
- Stage II: Lunate sclerosis visible on X-ray; the bone maintains normal shape and height.
- Stage IIIA: Lunate collapse without carpal instability or scaphoid rotation.
- Stage IIIB: Lunate collapse with carpal instability — including scaphoid rotation (flexion) and proximal migration of the capitate.
- Stage IV: Advanced disease with generalized wrist arthritis affecting the midcarpal and/or radiocarpal joints.
Treatments
Treatment is guided by disease stage, patient age, activity level, and symptom severity.
Conservative treatment (Stage I–II): Wrist immobilization with a cast or splint to rest the lunate and reduce mechanical stress, activity modification to avoid heavy lifting and repetitive wrist use, and NSAIDs for pain management. In very early or asymptomatic cases, observation with periodic imaging may be appropriate.
Surgical treatment in active or progressive patients
Surgery is typically recommended when conservative treatment fails or when disease stage warrants intervention. Options are matched to stage:
- Joint leveling procedures (Stage I–IIIA): Radial shortening osteotomy or ulnar lengthening reduces stress on the lunate in patients with negative ulnar variance and may halt or reverse disease progression.
- Revascularization (Stage I–IIIA): Transfer of vascularized bone from the distal radius or other donor sites attempts to restore blood supply to the lunate.
- Core decompression (early disease): Drilling into the lunate to stimulate new blood vessel formation.
- Partial wrist fusion (Stage IIIB): Fusion of selected carpal bones (scaphotrapezio-trapezoidal or capitate-hamate fusion) reduces load on the lunate while preserving some wrist motion.
- Proximal row carpectomy (Stage IIIB–IV): Removal of the scaphoid, lunate, and triquetrum, allowing the capitate to articulate with the radius. Preserves motion and is well-suited for moderate disease.
- Total wrist fusion (Stage IV): Provides reliable pain relief at the cost of wrist motion — appropriate for heavy laborers or patients with failed prior surgery and extensive arthritis.
Rehabilitation
Hand therapy is an important component of recovery after surgery, focusing on restoring range of motion, grip strength, and functional wrist use. Recovery timelines vary significantly by procedure — from several months for joint leveling procedures to 6–12 months for more complex reconstructions or fusions.
Get an MRI to Confirm Your Diagnosis
Before surgical planning or starting treatment, a clear MRI diagnosis ensures the right path forward. First Look MRI offers self-pay Wrist MRI scans — no doctor's order or insurance required — at our locations in Georgia, Texas, and Colorado.