Orthopedics - Oleksa A.P. 2006

Occupational musculoskeletal disorders
Aseptic osteonecrosis of the lunate bone

Work involving strain on the upper extremities, particularly overload of the wrist joint region, can lead to pathological Changes in the lunate bone of the carpus. This is due to its specific anatomical position: the bone occupies a central Location in the carpus, positioned between the capitate and radius, and during physical exertion, mechanical forces have the most damaging impact on it.

The condition manifests as a dull ache in the wrist joint area, which intensifies during or after work. After several months, Swelling develops. Routine muscular strain at work triggers a recurrence of pain accompanied by swelling on the DORSAL SIDE OF the wrist. These symptoms subside once the load is removed.

Over time, movements in the wrist joint become increasingly restricted and painful. Palpation over the PROJECTION OF THE lunate bone also elicits pain. Finsterer's sign appears: when the hand is clenched into a fist, the HEAD of the third metacarpal bone lies on the same level as the heads of the adjacent second and fourth metacarpals, rather than protruding above them as observed normally.

Sharp pain is provoked by tapping on the head and along the axis of the third metacarpal bone, especially when the hand is clenched into a fist.

The Diagnosis of avascular Necrosis of the lunate bone is primarily based on radiological findings and the determination of relative bone density.

Radiologically, pathological changes may not be detectable in the early stages. Only 4–5 weeks after the onset of the disease do changes in the structural pattern of the lunate bone appear; its shadow becomes more intense compared to that of adjacent Carpal Bones, indicating pseudosclerosis, i.e., osteonecrosis. Determining bone density via computed tomography allows for an even earlier diagnosis.

In the late Stages of the disease, radiography reveals deformation, axial flattening, and transverse shortening; the bone contours are irregular, with radiolucent areas in the center. Occasionally, narrowing of the joint space and signs of deforming osteoarthritis are detected.

Conservative Treatment is generally effective. Patients are prescribed long-term immobilization by applying a circular plaster cast to the wrist joint area, along with procaine (0.5% solution) blocks, hydrogen sulfide mud therapy, paraffin therapy, and hydrogen sulfide baths.

Positive treatment outcomes can be achieved through multiple drilling of the lunate bone with a Kirschner wire to create channels into which Blood Vessels can grow, thereby accelerating reparative processes.

Some orthopedists perform the Matthi Procedure (1932)—curettage of necrotic masses from the bone. Under anesthesia and via a dorsal approach in the projection of the lunate bone, the transverse carpal ligament is incised, and the extensor tendons of the fingers are retracted to expose the bone. The cortical layer of bone is drilled, and using a small Volkmann spoon or another delicate instrument, the necrotic cancellous bone mass is curetted and the cavity is filled with a cancellous bone autograft.

Graft remodeling is monitored every two months. In the event of resorption of the necrotic lunate bone, its deformation due to compression, and the onset of pain caused by osteoarthritis that limits work capacity and impairs quality of life, arthroplasty using a silicone or other endoprosthesis is recommended for the patient.