Orthopaedic Surgery - Kienböck Disease

Basics

Kienböck disease is osteonecrosis, or avascular necrosis, of the lunate.

Progressive loss of lunate vascularity can lead to sclerosis, fragmentation, collapse of the lunate, altered carpal mechanics, loss of carpal height, and eventually secondary degenerative arthritis of the wrist.

The condition is also known as lunatomalacia.

Classification

The traditional staging system was described by Stahl and later modified by Lichtman.

Classification is based primarily on the radiographic appearance of the lunate and the degree of associated carpal collapse.

Stage 0

MRI demonstrates evidence of lunate osteonecrosis despite normal plain radiographs.

This represents very early disease.

Stage I

Plain radiographs are normal or may demonstrate subtle fracture lines within the lunate.

MRI may show abnormal signal consistent with osteonecrosis.

There is no lunate collapse.

Stage II

The lunate becomes sclerotic on radiographs, reflecting increased bone density associated with osteonecrosis.

Carpal alignment and lunate height remain relatively preserved.

Stage IIIA

There is collapse of the lunate, but major fixed carpal malalignment has not yet developed.

In the modified Lichtman classification, the radioscaphoid angle remains less than approximately 60°.

Stage IIIB

Lunate collapse is accompanied by:

Proximal migration of the capitate, fixed flexion or rotation of the scaphoid, and loss of carpal height.

A radioscaphoid angle greater than approximately 60° is characteristic.

Stage IV

Advanced disease is characterized by generalized degenerative arthrosis of the wrist in addition to lunate collapse and carpal malalignment.

Additional Classification Systems

More recent systems incorporate findings from:

MRI, arthroscopy, cartilage assessment, and lunate vascularity.

These may help guide treatment more precisely than plain radiographs alone.

Epidemiology

Kienböck disease most commonly affects young adults between approximately 20 and 40 years of age.

Sex

A consistent overall sex predominance has not been established, although the disorder has historically been reported more frequently in young, physically active male manual workers.

Pediatric Disease

Kienböck disease can occur in children and adolescents.

The prognosis may be more favorable in younger patients because of greater healing and remodeling potential.

Risk Factors

Several anatomic and vascular factors may increase susceptibility.

Negative Ulnar Variance

An ulnar-negative wrist refers to a distal ulna that is relatively shorter than the radius.

This configuration can increase the proportion of load transmitted through the radial side of the wrist and potentially increase stress across the lunate.

Negative ulnar variance has therefore historically been associated with Kienböck disease.

Lunate Vascularity

Some lunates receive blood from a relatively limited vascular pattern, occasionally through a single dominant nutrient vessel.

Reduced vascular redundancy may increase susceptibility to ischemic injury.

Hematologic Disease

Conditions that impair bone perfusion, such as sickle cell disease, may predispose to lunate osteonecrosis.

Trauma and Ligament Injury

Traumatic disruption of carpal ligaments or repeated wrist loading may alter forces across the lunate and contribute to disease development.

Genetics

No consistent hereditary or genetic pattern has been identified.

Etiology

The exact cause remains uncertain.

When Kienböck originally described the disorder in 1910, it was considered a form of lunate softening or osteomalacia.

Current understanding favors a multifactorial process involving impaired blood supply combined with repetitive mechanical stress.

Ischemic Theory

Loss or compromise of the lunate blood supply may cause bone death and structural weakening.

Mechanical Theory

Repetitive microtrauma or abnormal load transmission may produce repeated injury to a vulnerable lunate.

Combined Mechanism

The prevailing concept is that repetitive stress acts on a lunate already predisposed by vascular or anatomic factors.

Diagnosis

History

Most patients present with a gradually developing combination of:

Dorsal wrist pain, stiffness, reduced grip strength, and difficulty with loading activities.

Symptoms may initially be mild or intermittent.

Pain Location

Pain is usually centered over the dorsal central wrist in the region of the lunate.

Grip Weakness

Some patients complain more prominently of decreased grip strength than pain.

Progression

If disease advances, symptoms may become progressively worse and eventually reflect secondary wrist arthritis.

Trauma History

A number of patients report a recent wrist hyperextension injury, although it is not always clear whether the injury caused the disease or simply made an existing process symptomatic.

Physical Examination

Tenderness

Tenderness may be present over the:

Dorsal lunate and central wrist.

Some patients may also report discomfort near the anatomic snuffbox.

Range of Motion

Wrist flexion and extension may become restricted as disease progresses.

Grip Strength

Grip strength is frequently reduced compared with the opposite hand.

Swelling

Mild dorsal wrist swelling may occasionally be present.

Imaging

Plain Radiographs

Standard wrist radiographs usually include:

PA, lateral, and oblique views.

Radiographs may establish the diagnosis once structural changes develop.

Early Disease

Stage I disease may have normal radiographs or show only a subtle lucent or fracture-like line within the lunate.

Sclerosis

Stage II disease demonstrates increased density or sclerosis of the lunate.

Collapse

More advanced stages demonstrate:

Lunate flattening, fragmentation, loss of height, carpal collapse, and proximal capitate migration.

Ulnar Variance View

A standardized PA radiograph can be used to assess ulnar variance.

Historically, this has been obtained with the:

Shoulder abducted to approximately 90°, elbow flexed to 90°, and forearm in neutral rotation.

Correct positioning is important because forearm rotation can alter the apparent ulnar variance.

MRI

MRI is particularly useful in early disease when plain radiographs remain normal.

It can demonstrate:

Abnormal lunate marrow signal, areas of necrosis, residual vascularity, fracture lines, and surrounding marrow changes.

MRI also contributes to assessment of disease extent and potential treatment planning.

CT

CT can provide detailed assessment of:

Lunate fracture, fragmentation, collapse, sclerosis, and carpal architecture.

It may be especially useful for operative planning.

Arthroscopy

Wrist arthroscopy may allow direct evaluation of the articular cartilage of the lunate, radius, and adjacent carpal bones.

Cartilage status can influence whether a reconstructive or salvage procedure is appropriate.

Pathological Findings

Biopsy specimens demonstrate features typical of osteonecrosis, including dead bone and altered marrow architecture.

Lunate Fracture

A transverse fracture through the lunate is a commonly described structural failure pattern.

Repeated loading across necrotic bone may contribute to collapse.

Differential Diagnosis

Important alternative diagnoses include:

Scapholunate ligament injury, scaphoid fracture, perilunate injury, degenerative wrist arthritis, and ulnar impaction syndrome.

Scapholunate Ligament Injury

Scapholunate instability can cause dorsal central wrist pain and altered carpal alignment that may mimic later-stage Kienböck disease.

Scaphoid Fracture

A scaphoid fracture should be considered when there is radial-sided wrist pain, particularly after trauma.

Perilunate Injury

Perilunate dislocation or ligament injury may produce significant wrist pain and carpal malalignment.

Ulnar Impaction Syndrome

Ulnar-sided wrist pain related to positive ulnar variance differs mechanically from the negative ulnar variance classically associated with Kienböck disease.

Treatment

General Principles

Optimal treatment remains debated.

Management depends on:

Patient age, symptoms, disease stage, ulnar variance, degree of lunate collapse, carpal alignment, cartilage condition, and functional demands.

Initial Management

The wrist may initially be:

Splinted or immobilized, with referral to a hand or wrist specialist.

Activity modification and analgesia may also be used during the early symptomatic phase.

Natural History

Radiographic disease can progress even when symptoms are modest.

However, the relationship between radiographic progression and clinical disability is variable.

Some patients remain functional despite substantial imaging abnormalities.

Young and Elderly Patients

Children younger than approximately 15 years and elderly patients older than approximately 70 years may have a more favorable clinical course with nonoperative management.

Observation is therefore often reasonable initially in these groups.

Persistent symptoms beyond several months may prompt reconsideration of surgery.

Treatment According to Stage

Stage I and Stage II

Treatment aims to:

Reduce mechanical loading across the lunate and improve or preserve its blood supply.

Joint-Leveling Procedures

When negative ulnar variance is present, a radial shortening osteotomy may reduce load across the lunate.

Historically, ulnar lengthening has also been used, although radial shortening is more commonly performed.

Capitate Shortening

A capitate shortening osteotomy is another load-reducing option in selected patients.

Limited Intercarpal Fusion

Selective fusion procedures can redistribute forces away from the diseased lunate while preserving some wrist motion.

Revascularization

Vascularized bone grafting may be used in selected early-stage disease to improve lunate perfusion.

The graft may provide both:

Biologic revascularization and structural support.

Stage III Disease

When lunate collapse has occurred, treatment becomes more dependent on:

Carpal alignment, cartilage condition, age, and degree of collapse.

Proximal Row Carpectomy

A proximal row carpectomy removes the:

Scaphoid, lunate, and triquetrum.

This can provide pain relief while preserving a functional range of wrist motion in appropriately selected patients.

It requires relatively preserved cartilage at the capitate head and lunate fossa of the radius.

Limited Fusion

Partial wrist fusion may be used to stabilize the carpus and reduce pain while maintaining some movement.

Stage IV Disease

Stage IV disease involves established degenerative arthritis.

At this stage, reconstructive procedures aimed solely at preserving the lunate are generally no longer sufficient.

Total Wrist Arthrodesis

Total wrist fusion provides reliable pain relief and stability but eliminates wrist flexion and extension.

It is often preferred in high-demand patients with advanced arthrosis.

Total Wrist Arthroplasty

Total wrist replacement may preserve motion in carefully selected lower-demand patients.

Implant longevity and activity restrictions must be considered.

Physical Therapy

Physical therapy generally has a limited role before definitive treatment.

It may be useful after surgery for:

Edema control, finger motion, scar management, gradual restoration of wrist motion when permitted, and strengthening.

Follow-Up

Prognosis

Untreated disease may progress to:

Lunate collapse, carpal malalignment, and secondary degenerative wrist arthritis.

However, the clinical course is variable, and not every patient with radiographic progression develops severe disability.

Children

Children tend to have a more favorable prognosis because of greater potential for revascularization and remodeling.

Complications

Potential complications of progressive Kienböck disease include:

Increasing wrist pain, mechanical clicking, loss of grip strength, reduced range of motion, carpal collapse, and secondary wrist arthritis.

Surgical Complications

Depending on the procedure, complications may include:

Nonunion of an osteotomy or fusion, stiffness, hardware irritation, persistent pain, progression of arthritis, and need for later salvage surgery.

Patient Monitoring

Even when surgery is not initially performed, patients should be followed periodically.

Monitoring should assess:

Pain, grip strength, wrist range of motion, functional limitation, lunate sclerosis or collapse, carpal height, scaphoid rotation, and progression of arthritis.

Serial radiographs are useful for detecting structural progression, while MRI may be used when early disease activity or lunate viability remains uncertain.