Step 1: Defining Kienbock disease.
Kienbock disease is a wrist condition involving avascular necrosis of the lunate bone.
This implies a compromised blood supply to the lunate, resulting in bone tissue death.
Step 2: Explaining lunate vulnerability.
The lunate bone has a fragile blood supply, mainly from small radial and ulnar artery branches.
Insufficient or damaged vessels lead to lunate necrosis, while other carpal bones are typically unaffected.
Step 3: Clinical manifestations.
Patients experience chronic wrist pain, stiffness, and reduced grip strength.
Radiographs may show sclerosis, collapse, and fragmentation of the lunate.
Step 4: Evaluating options.
- (A) Lunate: Correct, as it is the bone affected in Kienbock disease.
- (B) Scaphoid: Prone to fracture and avascular necrosis, but not Kienbock disease.
- (C) Trapezoid: Rarely affected by avascular necrosis.
- (D) Trapezium: Linked to thumb carpometacarpal arthritis, not Kienbock disease.
Step 5: Conclusion.
The lunate bone is specifically impacted by Kienbock disease.