gms | German Medical Science

Objectives/Interrogation: Isolated lunate dislocation is one of the most severe carpal instability lesion. Despite devastating changes in wrist anatomy it can be misdiagnosed. We present a case of an isolated lunate dislocation diagnosed 14 weeks after injury with avascular necrosis (AVN) of the lunate.

Methods: A 37-years-old male, a manual worker injured his right (dominant) wrist during a fall. He was initially diagnosed as a wrist sprain. One month later due to a persistent pain, an X-ray was performed with no recognition of wrist pathology. The patient came with a stiff wrist to an outpatient clinic 14 weeks later. His pain was 8 in the Visual Analogue Scale (VAS). The wrist was swollen with no active range of motion (AROM). Grip strength was 12% of the opposite hand, Mayo Wrist Score-5, and Disabilities of the Arm, Shoulder and Hand (DASH)-76.2. The symptoms of the median nerve dysfunction were present. The radiograms were reevaluated with a diagnosis of a lunate dislocation.

The patient was qualified for surgery. Preoperatively, computed tomography confirmed the isolated lunate dislocation with an injury of proximal capitate cartilage.

From volar and dorsal approaches a severe damage to the cartilage of the capitate and a fibrosis of the lunate were identified. The lunate was necrotic with loss of the cartilage and was excised. Due to a chondromalacia of the capitate, a proximal row carpectomy was excluded. We chose a proximal osteotomy of the capitate and a free cortical graft to remodel the shape of the capitate. A graft from the iliac crest was harvested to preserve its convex shape covered with soft tissue to be positioned as the new articular surface facing radiocarpal joint. The graft and remaining capitate were stabilized with a cage plate. The scaphoid and the capitate were fixed with a cannulated screw.

A bone union was achieved after 8 weeks. In a 6 months follow-up the pain was 0-1 in VAS, Mayo Wrist Score (80), DASH (10.9) and AROM and grip strength - 70 % of the opposite hand. The patient has returned to his previous occupation.

Results and Conclusions: This is the first report of a modified proximal capitate osteotomy with a free bone graft in the lunate dislocation with the AVN of the lunate with a coexisting chondromalacia of the capitate. Our method reduces the potential risk of double non-union and capitate head necrosis observed in the Graner's procedure as there is only one bone-union necessary. We assume that our modification could be an attractive option for the advanced Kienbock disease.