Basic principles of Kienböck's disease: Anatomy and vascularization of the lunate

Purpose: The purpose of this study was to assess the anatomy and vascularization of the lunate. We correlated vascularization patterns with lunate morphology, ligament tears and the degree of arthrosis. The findings will be correlated with the major existing theories of the cause of Kienböck's disease. Material and methods: We studied 24 cadaver upper limbs using latex injection and the Spalteholz technique. We investigated the extra and intraosseous blood supply to the lunate. We evaluated the incidence and distribution of anatomic features, arthrosis, and soft tissue lesions. Results: The lunate morphology was 5 type I (20.8%), 18 type II (75%) and 1 type III (4.2%). The lunate was found to have a separate facet for the hamate in 11 cases (45.8%). The most common size of the facet was found to be 3 mm (range, 3-6 mm). Arthrosis was identified most frequently in radius (88.2%) and lunate (94.1%). The triangular fibrocartilage complex (TFCC) was found tom in 58.3%, the lunotriquetral interosseous ligament (LTIL) was tom in 20.8% and the scapholunate interosseous ligament (SLIL) was torn in 54.2% of the wrists. There was a correlation between the presence of arthrosis at the proximal pole of the hamate and the presence of a lunate facet (p= 0.027) and a correlation between the presence of a tear in the SUL and arthrosis in the scaphoid (p= 0,002). The nutrient vessels entered the lunate through the dorsal and volar poles in all the specimens. The dorsal intercarpal and radiocarpal arches supply blood to the lunate from a plexus of vessels located directly over the lunate's dorsal pole. Vessels entered the dorsal aspect of the lunate through one to three foramina. Two to five nutrient vessels were observed entering the volar pole through various ligament insertions, including the ligament of Testut-Kuentz (radioscapholunate ligament) and the radiolunate triquetrum ligament (or dorsoradial carpal ligament) and ulnar lunate triquetral ligament. Conclusions: The lunate had consistent dorsal and palmar arteries entering the bone in all the specimens. The blood supply and foramina number is greater in the volar pole of the lunate than the dorsal pole. The lunate blood supply comes from different ligaments. In the aetiopathogeny of Kienböck' disease it is possible that an acute or chronic, traumatic or non-traumatic lesion of the vessel bearing ligaments, particularly because of their structure and the location of the radioscapholunate ligament of Testut-Kuentz, may have an important role in the appearance of lunate necrosis.