Avascular Necrosis of the Lunate.
Edited By: Thomas Trumble, M.D.
Last updated Thursday, March 17, 2005
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About
Basics of kienbock's disease
Kienbock’s disease is an idiopathic condition, meaning there is no known
cause. The pathology results from
ischemia and subsequent necrosis of the lunate, one of the primary bones of the
wrist. As the lunate collapses, the
wrist undergoes a predictable pattern of arthritic degeneration and coinciding
instability. Patients will often
complain of site-specific pain, weakness, and mechanical symptoms (clicking, clunking,
subjective instability, and stiffness).
Depending on the stage at presentation, different modalities of
treatment are available.Immediate medical attention
The earliest symptom is pain on the mid-dorsal aspect of
the wrist. It may or may not be preceded
by a history of trauma. Some authors
believe it is caused by repetitive micro-trauma; however, most cases are not
precipitated by any identifiable injury.
Associated with the pain patients may report local swelling, weakness,
and decreased wrist extension . The pain
will precede any findings on plain radiographs.
It may be detected earlier on MRI. Once a diagnosis of Kienbock’s disease is
made, immediate referral to an orthopedic surgeon is indicated.
Prognosis
Once it is determined that the lunate has sustained a
vascular insult, immediate intervention is warranted. The condition follows a predictable pattern
of arthritic degeneration which leads to progressive and debilitating pain with
loss of function. In the rare instance
the lunate may spontaneously
revascularize before the onset of arthritis; however, this should not be
hoped for and treatment should not be delayed.Lethality
The symptoms are limited to the affected wrist. There are no systemic manifestations of
Kienbock’s disease and it is not fatal.Pain
One of the earliest manifestations of Kienbock’s is
mid-dorsal wrist pain. As the arthritis
spreads, the pain increases and becomes more diffuse. It is aggravated by any activities that cause
compression loading of the wrist, particularly with extension. Debilitation
The pain eventually becomes debilitating as the
arthritis spreads to involve the whole wrist.
Patients will experience not only pain with activities but also at
rest. It will interfere with the ability
to perform even sedentary work and often wakes them from sleep. Increased dependency on analgesics is common.Comfort
The pain eventually becomes debilitating as the
arthritis spreads to involve the whole wrist.
Patients will experience not only pain with activities but also at
rest. It will interfere with the ability
to perform even sedentary work and often wakes them from sleep. Increased dependency on analgesics is common.Curability
If diagnosed early, interventions can unload the lunate
and potentially allow for revascularization.
The choice of treatment is determined by the anatomy of the individual
(ulnar variance) and the stage of disease.
Once
the arthritis becomes more widespread, only salvage procedures can be
attempted. These typically involve a
series of bony fusions or resections directed at ablating arthritic
joints. This alleviates the pain but
also results in decreased motion and strength.
Fertility and pregnancy
Kienbock's disease will not change the patient's ability to have children or get pregnant.Independence
The progressive and debilitating nature of Kienbocks
disease often interferes with a person’s independence. The pain and loss of use of the affected
extremity often affects vocation, recreation, and activities of daily living
(personal hygiene, cooking, cleaning, ability to dress, etc.)Mobility
Kienbock's disease will not change the patient's ability to move about.Daily activities
The pain tends to be aggravated by activities that
load the wrist. Initially this may only
interfere with heavy labor or sports but as the arthritis progresses, it
typically will limit basic activities of daily living. Eventually the pain will be present even with
inactivity and will wake patients regularly at night.Energy
Fatigue may result from lack of restful sleep and the
stress of chronic pain. Otherwise,
kienbock’s does not have any systemic manifestations and will not affect a
patient’s metabolism.Diet
Kienbock's disease will not require a change in diet.Relationships
The effects of chronic pain, loss of work,
restrictions in recreational pursuits,
and loss of sleep will strain relationships both at work and home. Other impacts
The condition is not contagious and does not spread to
other joints in the body. The
restrictions and limitations are associated with the loss of use of the
extremity. This may be secondary to the
pain or as a consequence of surgical interventions directed at treating the
pain.Incidence
The condition tends to affect males in their third or
fourth decades. It is usually limited to
one wrist. Certain individuals may be
predisposed due to anatomic variations in blood supply, ulnar length, and
lunate shape:
1. Vascular
There are various patterns of blood supply to the lunate
including “X”, “I”, and “Y” patterns.
Between 7 and 26 percent of lunates have only one artery supplying them
(“I” pattern), with 31 percent having no arterial branching within the lunate (Gelberman, Bauman et al. 1980; Panagis,
Gelberman et al. 1983). This pattern may render the lunate more susceptible
to avascular necrosis, as injury to the single vessel cannot be compensated by collateral flow.
2. Load distribution
a. Ulnar Variance
The length of the distal ulna with respect to the distal
radius in the AP plane is called ulnar variance. A shorter ulna, or negative
ulnar variance, may lead to increased load across the radiolunate articulation,
with increased risk of lunate avascular necrosis. This relationship has been
shown in some studies; others have found no such correlation, and since
Kienböck’s disease occurs in individuals with neutral and even positive ulnar
variance, other factors must be involved as well.(Gelberman, Salamon et al. 1975; Chen and Shih 1990; Coe and
Trumble 1993; Weiss 1994)
b. Lunate Shape
The geometry of the lunate itself and of surrounding bones may also be
significant.
One investigator noted a tendency toward a smaller lunate in his
patients with the disorder.(Tsuge and Nakamura 1993) Three different patterns of lunate morphology at the
articulation with the scaphoid, radius, and triquetrum have been described
along with findings that the vascular foramina tended to occur in proximal
triangular areas of the bone, such that some lunate specimens are less well
vascularized than others.
Acquisition
Kienbock’s is idiopathic
meaning there is no known etiology.
However, as previously discussed, it likely results from both being
predisposed (triangular lunate, negative ulnar variance, “I” pattern artery) as
well as being exposed to environmental influences (repetitive trauma).
No
single factor has been attributable to causing Kienbock’s disease.Genetics
There is no familial pattern of inheritance for
Kienbock’s disease.Communicability
Kienbock's disease is not contagious.Lifestyle risk factors
Exposure to repetitive trauma is a risk factor. Activities that involve compression loading
of the wrist particularly in extension (eg jackhammers) have been postulated to
cause vascular injury.
Other
generic risk factors for avascular necrosis include history of steroid use,
sickle cell anemia, exposure to increased barometric pressure (eg diving), and
smoking. These risk factors are not
particular to Kienbock’s and have been documented more commonly in the hip,
knee, and shoulder.
Injury & trauma risk factors
Trauma is the most common postulated etiology for
Kienbock’s. This can take the form of a
single traumatic episode such as a fracture dislocation of the wrist from a car
accident or it may include repetitive microtrauma such as compression loading
from using a jackhammer.Prevention
There is no prophylaxis against Kienbock’s since you
cannot identify individuals at risk.
Manual
jackhammers have largely been replaced with hydraulic ones. Other than this intervention in the
workplace, there are no guidelines for primary prophylaxis against Kienbock’s.
Anatomy
Kienbock’s is avascular necrosis of the lunate which
is one of the eight bones that make up the carpus. The carpus consists of two rows of four small
bones that lie directly distal to the wrist joint. In fact, the proximal row of the carpus forms
part of the wrist, or radiocarpal joint.
The lunate is a central bone of the radiocarpal joint. It articulates
directly with the distal radius. It has
key ligamentous attachments that stabilize the rest of the carpus. When it collapses, the biomechanics of the
wrist are altered in such a way that causes sequential degenerative changes
throughout the radiocarpal and intercarpal joints. Initial symptoms
Earliest symptom is central dorsal wrist pain that is
aggravated by loading maneouvres such as compression in wrist extension (eg
push-up position). Symptoms
Initially patients will report
central dorsal wrist pain that radiates up the forearm with associated
stiffness, tenderness, and swelling over the lunate.
Passive dorsiflexion of middle
finger may produce characteristic pain.
As the condition progresses,
patients will note a limitation of wrist motion (usually extension), and
weakness of grip.
As the lunate collapses and
degenerative changes develop the pain, weakness, and stiffness will increase
causing severe and chronic disability.
Progression
Initially patients will report
central dorsal wrist pain that radiates up the forearm with associated
stiffness, tenderness, and swelling over the lunate.
Passive dorsiflexion of middle
finger may produce characteristic pain.
As the condition progresses,
patients will note a limitation of wrist motion (usually extension), and
weakness of grip.
As the lunate collapses and
degenerative changes develop the pain, weakness, and stiffness will increase
causing severe and chronic disability.
Secondary effects
There are no systemic effects of Kienbock’s. All the symptoms are directly related to
collapse of the lunate and spread of arthritis through the carpus.Conditions with similar symptoms
There are numerous conditions that can cause central
dorsal wrist pain. These may originate
from the subcutaneous tissues (tumors, neuromas), extensor tendons
(tenosynovitis), joint capsule (dorsal wrist ganglion), ligaments (scapholunate
tears, SLAC wrist, SNAC wrist), and joint (arthritis).
Accurate
diagnosis requires thorough history, physical examination, investigations,
follow-up, and vigilance for the condition.
Surgery for Kienbock's Disease at the University of Washington, Department of Orthopaedics and Sports Medicine, Seattle, Washington
If you are interested in making an appointment to discuss this procedure in Seattle, you can request an appointment using our online referrals website. To request a referral online, please click here. You can also call 206-598-BONE (2663) to make an appointment. Our clinical center is located in Seattle Washington, USA