Kienböck's disease in 2021.

The cause of Kienböck's disease is still unclear. It was initially considered as osteomalacia, before being recognized as avascular necrosis of the lunate. Its functional prognosis is doubtful, given that the progression often leads to wrist degeneration. Conservative treatment does not provide good results in adults; thus surgery is often needed. Certain anatomical factors such as the ulnar variance, configuration of the lunate or orientation of the radial glenoid have turned out not to contribute to necrosis but may contribute to lunate fracture. The lunate's vascularization can be precarious and mostly depends on the capsular arterioles. The lunate is a very mobile bone that participates in wrist movements, both in the radiocarpal joint and especially in the mid-carpal joints during activities of daily living. Radiographs are not the only diagnostic tools. The lunate makes contact with the radius and triangular fibrocartilage complex and is often subjected to high shear loads at the edge of the radius that can cause it to fracture. MRI and arthroscopy can contribute to the assessment. Kienböck's disease is likely an inflammatory, biological venous thrombosis disorder that leads to local damage due to intraosseous compartment syndrome. The basis of surgical treatment is to decompress the lunate to shield it from shear and compression loads. Existing osteotomy procedures will be described and compared to better understand their biomechanical effects. Some osteotomies do not reduce the loads transmitted to the lunate but can reduce the risk of intra-osseous shear. Some osteotomies may place excessive pressure on the lunate on its ulnar side. Some techniques are extra-articular and preserve the capsule's vascularization along with the anatomy of the mid-carpal joint. When the lunate damage is so severe that the bone's viability is compromised, bone grafting or replacement have been proposed. The palliative techniques typically used for wrist degeneration are indicated in the terminal stages. There are currently no effective biological treatments. While the origin of Kienböck's disease is still unknown, we now know that decompression osteotomies, while they do not heal the necrosis, protect the lunate from collapse, which hopefully provides enough time for biological healing to occur.