Kienböck's disease
Location of the lunate bone where Kienböck's disease develops

Definition

Kienböck's disease is a condition of the wrist caused by the degeneration of the carpal bone, lunate. This leads to pain and stiffness of the wrist.

X-ray shows the degeneration of the lunate that appears with more intense opacity compared to other carpal bones. This indicates lunate necrosis

Pathology

In Kienböck's disease the lack of blood perfusion in the lunate results in the degeneration and necrosis of the bone or osteonecrosis. Consequently, the lunate collapses causing a derangement of the other carpal bones, limited wrist movement and increasing pain. Eventually the deterioration of the wrist leads to osteoarthritic changes of the entire joint. In a prolonged condition, Kienböck’s disease can affect the function of the extensor tendons of the wrist and cause instability.

Left: scaphoid-lunate advanced collapse (SLAC) with severe osteoarthritis (stage IV). Right: post-surgery, intercarpal fusion and scaphoid resection

Classification

Kienböck's disease can progress over years in four distinct stages:

Stage I: early phase consists of initial loss of blood supply possibly associated with a fracture of the lunate

Stage II: the lunate begins to degenerate and becomes sclerotic. On X-rays it appears brighter. At this stage patients report pain, tenderness and swelling

Stage III: the lunate collapses and forms bone fragments shifting the position of other wrist bones. The symptoms worsen limiting the function of the wrist.

Stage IV: the necrosis and collapse of the lunate affects the surrounding bones causing osteoarthritis of the wrist.

Left: Distal radius intraarticular, displaced fracture; Middle: Older distal radius fracture with callus formation; Right: Distal radius and ulna fracture, extraarticular and displaced

No 2.

Intra-articular fracture extends to the wrist joint (or articulation)

Extra-articular fracture is located outside of the wrist joint

Open fracture when bone fragments perforate the skin

Comminuted fracture when the bone breaks into multiple fragments

Non-displaced when the anatomical alignment of the bone is maintained or displaced when the bone fragments move apart.

Melone’s classification describes the characteristics of intra-articular fractures of the radius:

i    Stable fracture

ii    Unstable "die-punch"

iii   "Spike" fracture

iv Split fracture

v   Explosion injuries

Acetabular fracture of the pelvis

Acetabular fractures

These fractures are divided into:

Anterior pillar (not weight bearing part of joint)

Posterior pillar (often associated with dislocation of the hip including the weight bearing part of joint)

Transverse

Comminuted involving both column type 

Sacral / coccygeal fractures

The sacrum is a triangular-shaped bone formed by 5 fused vertebrae, which provide a posterior wall to the pelvic ring. At each side of the sacrum, the ala structures articulate with the ilium bones forming the sacro-iliac joints. Sacral fractures are usually parallel to the spine and can involve the ala. Less frequently sacral fractures may display an “H” shape, including a transversal fracture uniting both sides of the sacrum. Three zones are described where sacral fractures can occur that are along vertical lines relative to the alignment of the foramina. Sacral fractures may result in sacral instability and require treatment via sacroplasty (injection of bone glue into the fracture). Surgery is necessary in case of associated neurological symptoms.

Fractures of the coccyx involve the tailbone, the terminal portion of the spine situated below the sacrum formed by 3 to 5 fused vertebrae. Coccyx fractures occur when falling on a seated position. They are more common in elderly women and seldom require surgical treatment.

Approximately 10% of individuals with cerebral palsy develop Kienböck's disease

Causes

The causes of Kienböck's disease are unknown. The pathology is thought to arise from previous repetitive injuries of the wrist. The normally poor vasculature in this region seems more likely to increase the predisposition to this disease. The shorter length of the ulna bone in some individuals may deliver excessive pressure on the wrist and affect the integrity of the lunate including the reduction of blood supply. Kienböck's disease can be associated with other medical conditions affecting small vessels and bone integrity (osteoporosis).

Repetitive pressure onto the wrists may lead to Kienböck's disease

Risk factors

The list below comprises a few potential risk factors for developing Kienböck’s disease:

Adults between 15 and 40 years of age

Gymnasts subject to frequent wrist sprains

Use of medications (steroids)

Systemic diseases such as osteoporosis may predispose to the disease

Pain in the wrist is the main symptom of Kienböck's disease

Symptoms

The symptoms arising from a Kienböck's disease are:

Pain in the wrist particularly during motion, which over time becomes chronic, also without activity

Tenderness at touch

Weakness of grip function

Stiffness

Swelling

Wrist instability following lunate necrosis in advanced pathology (stage IV)

Assessment of wrist stability and function begins the diagnostic examination

Diagnosis

Kienböck's disease is often diagnosed late when it has progressed significantly. Medical history focuses on discussing previous wrist dislocations and injuries. Clinical examination of the wrist will determine:

Changes in the anatomy of the affected wrist against the healthy wrist

Tenderness when applying gentle pressure on the wrist

Pain with movement

Changes in the range of movement

X-rays are taken to determine alteration of the lunate bone in relation to the adjacent carpal bones, the presence of fractures, bone necrosis and collapse. This diagnostic tool also enables the classification of the disease stage. CT scan and MRI may be used for superior detection of anatomical changes in the wrist and assess blood perfusion.

Treatment

Immobilisation is the first approach for conservative treatment of Kienböck's disease

Nonoperative treatment

The management of the Kienböck's disease in early diagnosis (Stage I) aims at restoring blood supply to the lunate to prevent further bone degeneration. Immobilisation of the wrist with a cast or splint for 3 weeks up to 3 months relieves the pressure on the lunate. This can achieve a full recovery of blood perfusion to the bone. Additional treatments include:

Administration of NSAIDs

Painkillers

Frequent monitoring to assess disease progress

Wrist fusion concomitant to ulnar osteotomy (partial resection of the ulna)

Surgical treatment

Surgery is required at later stages of Kienböck's disease when the lunate underwent evident degeneration and surgical treatment is required. Several options are available which depend on the disease stage.

Revascularisation (Stages I and II): this consists in the transplantation of a healthy, vascularised bone usually taken from the forearm (mostly radius) into the lunate bone. This procedure may be supported temporarily by an external fixator to keep the graft in correct position while healing.

Intercarpal fusion: often using an arthroscope the lunate bone is fused with other carpal bones using metal implants.

Lunate excision: in this older method, the lunate is removed and often replaced with artificial bone to keep a functional wrist anatomy.

Joint leveling (Stage II): when Kienböck's disease is caused by a shorter ulna, surgical lengthening of the ulna or shortening of the radius (osteotomy) can restore a normal balance of the forearm and wrist and reduce pressure to the lunate.

Capitate or carpal bone shortening (Stage IV): the reduction of the carpal length will also ease the pressure to the lunate bone.

Carpectomy (Stage III-IV): in case of lunate necrosis and wrist osteoarthritis one or all four proximal carpal bones are removed. This will facilitate wrist movement.

Wrist fusion (Stage IV): with full arthritis of the wrist this is the last resort to alleviate pain at the expense of a stiff wrist. A metal plate is fixed from the radius through the carpal/metacarpal bones.

Complications

The main complications after surgery of Kienböck’s disease include:

Infection

Failure in achieving revascularisation of the lunate or bone graft

Unsatisfactory wrist function

Wrist instability

Residual pain

Massage and mobilisation of the wrist follows the initial immobilisation

Rehabilitation

Following surgery, a cast or splint is worn for up to 12 weeks while monitoring regularly the healing process via repetitive X-rays. A physical or occupational therapist plans exercises to restore flexibility and strength of the wrist including fine movement of the hand and fingers. Education will inform the patient on how to modify activities to avoid strain on the wrist. Standard rehabilitative therapy includes:

Massage

Joint mobilisation

Stretches

Electrotherapy

Return to activity plan

Taping / bracing

Protecting the wrist from the pressure of sport activities may help preventing Kienböck's disease

Prevention

The optimal approach to prevent a full blown Kienböck's disease is to achieve an early diagnosis of the condition to avoid the irreversible necrosis of the lunate bone and wrist osteoarthritis. Gymnasts may protect the wrist with taping during training.