Kienböck’s disease is a nonspecific osteonecrosis of the semilunar bone. Initially, it proceeds asymptomatically or is accompanied by non-intense pain during physical exertion. Then, against the background of bone destruction, a pathological fracture is formed. Pain, restriction of movements increase, the muscles of the forearm gradually atrophy. In the outcome of the disease, a deformity of the semilunar bone of varying severity is formed. The diagnosis is made on the basis of survey data, examination, radiography, CT, MRI. Surgical treatment – partial arthrodesis, revascularization, bone grafting.
M93.1 Kienböck’s disease in adults
Kienböck’s disease (osteochondropathy of the semilunar bone, aseptic or avascular necrosis of the semilunar bone) is a disease accompanied by isolated destruction of the wrist bone involved in the formation of the wrist joint. It is quite rare, usually people 20-40 years old who are engaged in manual physical labor suffer. The leading arm is mainly affected (right–handed – right, left-handed – left), in 10% of cases the pathology is bilateral. Men get sick more often than women.
The etiology of Kienböck’s disease has not been definitively established. The Austrian radiologist, whose name has been bearing this disease since 1910, considered dystrophic changes in the semilunar bone a distant consequence of trauma. The cause of the disease was also called circulatory disorders on the background of embolism and vascular damage. Currently, pathology is considered as polyethological, as provoking factors indicate:
- repeated microtrauma with significant loads on the brush;
- compression fractures of the semilunar bone;
- unrecognized pathological fractures due to cystic bone defects;
- congenital shortening of the ulna (anatomical variant of the norm), which increases the load on the semilunar bone.
Due to the passage of the typical stages of avascular necrosis, pathology is attributed to osteochondropathies. At the same time, experts emphasize that Kienböck’s disease differs from most osteochondropathies, since it develops in adults, and not in children or adolescents, there are no signs of bone restoration after the completion of the process.
Degenerative bone changes are provoked by deterioration of local blood supply due to overload and traumatic injuries. A zone of edema forms around the focus of degeneration, which also negatively affects local blood circulation. The processes of destruction prevail over the processes of restoration. Due to the defeat of a significant part of the bone, even with small traumatic effects, pathological fractures occur.
Against the background of impression fractures, the strength of bone tissue continues to decrease. Areas of necrosis and fibrous degeneration are formed on the articular surface, deformities are aggravated. The bone is fragmented. Articular surfaces lose congruence, arthrotic changes progress. The degree of final deformation varies from minor to severe.
In its development, Kienböck’s disease passes through five stages typical of aseptic bone necrosis in adult patients. These stages are to a certain extent conditional, since the destruction and degenerative degeneration of the bone are a continuous dynamic process, however, they help to choose the optimal treatment tactics and assess the prognosis of the disease. The classification is based on radiological changes:
- Stage 1 – X-rays without changes.
- Stage 2 – impression fractures are formed. The bone is moderately deformed, foci of darkening appear with a violation of the structural pattern.
- Stage 3 – cartilage, subchondral plate is involved. The deformity progresses, the articular gap expands.
- Stage 4 – the semilunar bone is divided into several vertical fragments.
- Stage 5 – the pictures show signs of deforming arthrosis.
In some cases, an asymptomatic course is observed, the pathology is detected by chance. In a typical case, the onset may be gradual or sudden. In the first case, discomfort and non-intense pain without a clear localization appear even before the fracture of the semilunar bone. Painful sensations are provoked by significant physical exertion, disappear at rest. In the second case, the first pain attack is noted against the background of a pathological fracture.
The pain is quite acute, but does not reach the same degree as with ordinary fractures. Movement restriction is insignificant. Then the intensity and duration of pain gradually increase. On palpation, the area of greatest pain is determined along the midline mainly on the back of the wrist. Local swelling is also detected there. The patient spares his hand during household and professional loads. The volume of movements in the joint decreases. Atrophic changes in the forearm muscles are progressing. There may be a crunch during movements.
Due to the increasing changes in the shape and structure of the semilunar bone, the navicular bone goes into the position of persistent subluxation. Over time, patients with Kienböck’s disease develop deforming arthrosis of the wrist joint. Some patients have carpal tunnel syndrome. Due to concomitant damage to the tendons, their pathological ruptures may form.
The diagnosis is established by an orthopedic or rheumatologist on the basis of complaints, objective examination data and additional studies. Imaging techniques play a crucial role in determining the nature of pathology. The diagnostic program includes:
- Physical examination. In the first 2-3 months (before the appearance of changes on radiographs), diagnosis can be difficult, due to the non-specificity and vagueness of symptoms. An indication of Kienböck’s disease at this stage may be local soreness in the projection of the semilunar bone and increased pain syndrome with intense movements in the wrist joint.
- Wrist joint x-ray. It is the main method of research. The X-ray picture corresponds to the stage of the disease. Changes in the shape, structure of the bone, impression fractures, fragmentation or signs of arthrosis are detected.
- Wrist CT and MRI. They are prescribed in doubtful cases at an early stage to detect changes that are not displayed on conventional radiographs.
Clinical differentiation in traumatology is carried out with deep hygromas of the wrist joint, stenosing ligamentitis, semilunar bone cyst, ligament damage. Taking into account the peculiarities of the X-ray picture, Kienböck’s disease is distinguished with tumors, tuberculous ostitis, rheumatoid lesions of the wrist bones.
Conservative treatment is indicated at the initial stage of the disease, before the formation of impression fractures. Immobilization using an orthosis, splint, plaster or polymer bandage for a period of 1 month is recommended, followed by rehabilitation measures, including physical therapy, massage and physiotherapy.
In some cases, this approach allows restoring blood supply to the semilunar bone by improving blood flow through old vessels or revascularization. In the later stages and with an unfavorable course of the disease, conservative therapy is ineffective, it only temporarily reduces the pain syndrome and somewhat slows down the destruction of the semilunar bone.
Taking into account the stage and severity of the pathological process , the following surgical interventions can be used:
- Revascularization. It is carried out by moving a small vascularized bone graft. It is recommended in the absence of gross violations of the shape of the semilunar bone, preserving the functionality of the joint.
- Bone grafting. It is produced with extensive bone destruction using an autograft and bone chips.
- Reduction of a fragment of the cephalic bone. It is performed after removal of the damaged semilunar bone, L-shaped osteotomy of the head bone.
- Endoprosthetics. Sometimes the destroyed semilunar bone is replaced with an endoprosthesis, but such an operation is possible only with the subsequent refusal of hard physical labor.
In addition, partial arthrodesis is performed for patients with Kienböck’s disease. Complete arthrodesis of the wrist joint is rarely used, it is indicated only in severe deforming arthrosis. In the postoperative period, immobilization is carried out for 1.5-3 months, rehabilitation measures are carried out.
The prognosis for Kienböck’s disease is doubtful, it is difficult to predict the exact outcome. Complete recovery is rarely noted, even in the case of early treatment. There is a significant variability in the course of the disease – in some patients severe deformities are formed, in others the changes remain moderate or insignificant for many years. Surgical interventions in most cases provide a good or satisfactory long-term result.
Due to the unclear etiology, there are no unambiguous preventive recommendations. Taking into account the relationship between injuries, chronic overloads of the hand and Kienböck’s disease, patients are advised to optimize the load on the limb, observe the necessary precautions at home and at work.
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