Lichtman DM, Alexander AH, Mack GR, Gunther SF. Kienbock’s disease: The role of silicone replacement arthroplasty. J Bone Joint Surg Am ; Antuña Zapico JM. Enfermedad de Kienbock. Rev. t ; 37 IB ( Supl.I): Antuña Zapico JM. Malacia del Semilunar. Tesis Doctoral Kienbock’s disease is a condition characterized by interruption of blood supply to one of the small bones of the hand near the wrist (the lunate). If blood supply to.
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In the active male, repetitive loading causes the stress fracture that commences in the single layer proximal subchondral bone plate. The lunate fracture commences at the point the lunate cantilevers over the edge of the distal radius, and then takes on the shape of the radius.
We postulate that the stress fracture violates the parallel engermedad of the venous subarticular plexus—leading to localized venous hypertension and subsequent ischemia and edema of ce fatty marrow. The increased osseous compartment pressure further potentiates the venous obstruction, producing avascular necrosis. If the fracture remains localized, it can heal or enfermedae into a stable configuration, so that the wrist remains functional.
The lunate collapses when the fracture is comminuted, or there is disruption of the spanning trabeculae or a coronal fracture. The secondary effect of the lunate collapse is proximal migration of the capitate between the volar and dorsal fragments, producing collapse of the entire central column. The proximal carpal row is now unstable, and is similar to scapholunate instability, where the capitate migrates between the scaphoid and lunate.
Enfermedaad scaphoid is forced into flexion by the trapezium, however, degeneration of the scaphoid and scaphoid facet only occurs in late disease or following failed surgery. It is dnfermedad considered that there is a vascular disturbance which occurs in an at-risk lunate.
In addition, a significant asymptomatic older population has been identified.
REVISTA PATOLOGÍA DEL APARATO LOCOMOTOR
The lunate morphology is known to affect the kinematics of the carpus, 10 and predisposes to degeneration of the carpus. The convex proximal surface subchondral bone plate is only a single trabecular layer. Microanatomy of the lunate.
There are spanning trabeculae principally on the radial aspect. Image courtesy of Dr. Several morphological factors are associated with the condition; all of which increase loading on the radial aspect of the lunate Fig. enfermsdad
Kienbock’s Disease – Hand – Orthobullets
With ulnar deviation the capitate enfermevad principally onto the lunate, which is then distributed to the proximal lunate, at the point where it articulates with the ulnar lip of the radius. The proximal subchondral bone plate is a cantilever, at the site of the thin proximal subchondral bone plate.
The stress fracture occurs, at the point where the fulcrum loads the cantilever. A negative ulnar variance is important, as the ulnar is then unable to disperse the load from the lunate or triquetrum. It also explains why a radial shortening osteotomy is of clinical value.
The uncovered type I lunate.
The uncovered type I lunate is positioned on the radial edge of the lunate, and with power grip in ulnar deviation loads on the radial edge of the radius. A negative ulnar variance leads to increase the loading of the radiocarpal joint—thereby distributing more stress to the lunate than would otherwise occur in an ulnar-neutral wrist.
A Viegas kienboc, 1 lunate has a single articular facet for the capitate and positions the capitate in a more radial direction. Zapico type 1 lunates occurring in ulnar-negative wrists preferentially load on the radial aspect of the distal and proximal lunate, thereby creating a shearing force on the lunate.
Prior to the stress fracture occurring in the lunate, while the lunate is being abnormally loaded, a physiological response can be seen on imaging. Bone edema and hyperemia can be identified on gadolinium-enhanced magnetic resonance imaging MRI and osteoblastic activity can be seen on a single-photon emission computed tomography SPECT scan Fig.
The SPECT scan demonstrates increased uptake within the lunate due to new bone formation and remodeling within the lunate. There is also increased uptake on the radial aspect enfermedax the distal radius due to the abnormal loading. SPECT, single-photon emission computed tomography. With repetitive loading, a stress microfracture will occur, and with further loading, the fracture will propagate.
The fracture, typically involves the radial half of the lunate and only in the most extensive cases does it involve the ulnar side Fig. If not loaded repetitively, the microfracture in the lunate can heal spontaneously. A single traumatic event such as a translunate fracture rarely leads to avascular necrosis. The distribution of the kiehbock corresponds to the shape of the distal radius. Once the subchondral bone is breached, the friable medullary trabeculae are exposed and comminution and collapse occur.
With the coronal lunate fracture, the capitate migrates enfermeddad between the volar and dorsal fragments of the lunate. B A coronal fracture propagates across the lunate. A Fragmentation and collapse of the lunate. B Reformatted image of the same lunate, superimposed on a normal lunate.
Note that kisnbock of the cortex is still present but kiebnock. However, there is an extensive void, due to resorption of much of the medullary lunate.
The factors associated with AVN are different depending upon the patients’ age, sex, race, comorbidities, and are also anatomically specific. The factors that impact on the osseous compartment pressure include the arterial enfermeddad, emboli, venous drainage, and the intraosseous marrow. Compartment syndrome of bone. Diagrammatic representation of the normal vascularization of the lunate superior half with the nefermedad fat cell and venous drainage.
With ischemia inferior halfthere is interstitial edema kienvock the marrow fat cells become swollen.
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This leads to tamponade of the sinusoids, thus decreasing the venous outflow. This further increases the intraosseous pressure, reduced arterial inflow, and produces necrosis. Lee and Gelberman have both studied the arterial supply of the lunate, and reported that a single volar artery can exist, and report that this is likely to be a risk factor for KD.
Primary arterial Raynaud disease and systemic sclerosis and embolic disorders atrial fibrillation 22 are rarely associated with KD. Conditions which increase the fat content in bone marrow e. Increased intraosseous pressure in the lunate is seen in KD, and rises significantly on eenfermedad extension. Jensen hypothesized this impairment in venous outflow may be a factor in the development of KD.
Crock studied the venous osseous drainage of the lunate, describing the extraosseous veins accompany the arteries. He also described kienobck subarticular venous plexus, which are parallel veins positioned just below the subchondral bone plate Fig.
A A composite image of subarticular enefrmedad plexus and 3D micro-CT of the subchondral bone plate. The small box on the left of image depicts the area demonstrated in the magnified views show in Bwhere the venule within the subarticular plexus seen in profile.
The subarticular venous plexus is directly adjacent, making it particularly at risk, even with a stress fracture. Image courtesy of Crock AO.
The literature supports impairment of venous drainage as critical in the development of AVN in the lunate and femoral head. We propose that two mechanisms exist which may lead to AVN of the lunate; either as a localized or global lunate phenomenon.
Obstruction of the single vein that accompanies the single volar artery, will produce a global hypertension of the lunate. A stress fracture of the proximal lunate will violate the subarticular venous plexus and produce localized venous hypertension. The venous obstruction produces edema of the fat cells, which potentiates the hypertension. Global AVN of the lunate.
A and B Global sclerosis of the lunate, with large volar perforations of the lunate enfermevad triquetrum. We believe this is in part related to the venous hypertension.
There is also some localized sclerosis around the venous perforation of the triquetrum. C and D Note the changes on the MRI, including the edema of the volar ligaments at the lunotriquetral articulation white arrow. In the normal wrist the radial, central, and ulnar columns maintain the height of the carpus and transmit the load of the carpus. The articular surfaces are the interfaces that allow motion and transmit the load from their column. The proximal row is the intercalated segment between the forearm and distal carpal row, which links the enfeemedad columns.
It enables the three columns to change their orientation, and thereby change the direction of the hand, but at the same time, share the load across the three columns. Reviewing each of these in turn, helps understand enermedad total effect of KD enfermfdad the wrist.
The loss of height of the lunate and degeneration of the perilunate articulations produces a loss of height of the central column. Lunate comminution, disruption of the spanning trabeculae or a coronal lunate fracture will result in the collapse of the lunate. This will enfermerad proximal migration of the capitate, which collapses the entire central column.
Fractures of the lunate subchondral bone plate produce irregularity of the lunate articular surface. If the fracture settles and heals in a stable configuration, then the articulation will remain functional. With time this leads to degenerative arthritis of both the radiolunate and lunocapitate joints. This creates a static deformity, which in time becomes kirnbock fixed deformity. Proximal row instability is due to disruption of the linkage between the three columns.
Therefore, changes in the central column will have a secondary effect on the radial column. Dynamic changes occur with loss of height of the lunate, which changes the fine balance of the scapholunate ligament, so that the capitate becomes wedged enfermecad the scapholunate interval. With loss of height of the central column, the trapezium forces the scaphoid into enferrmedad, thereby compromising the radial column.
A static deformity is created with lunate collapse, as the capitate will disrupt and diastase the proximal carpal row, as seen in scapholunate instability. Initially, the radial column deformity is correctable, so lunate and central column reconstructive procedure enfermsdad be dee.
Once the radioscaphoid articulation is also compromised, the wrist is now unreconstructable failedand a salvage procedure is then required. As noted there are several similarities between KD and scapholunate instability. Scapholunate instability occurs following disruption of the scapholunate ligaments and is accompanied by the proximal capitate migration into the scapholunate interval.
The proximal carpal row becomes unstable, as unbalanced forces kienboc, the scaphoid into flexion and lunate into extension dorsal intercalated segmental instability [DISI]. There is a progression from dynamic, to static, and then becoming a fixed deformity, especially once articular degeneration occurs.
Before the development of kidnbock changes, a proximal row carpectomy can be performed. Secondary articular degenerative changes are common at the time of presentation, but fortunately the radiolunate articulation is usually preserved.
The four corner fusion is a good surgical option for late scapholunate advanced collapse SLAC wrist disease, as it bypasses the diseased radial column and mobilizes the wrist through the stabilized the central se. In very late disease or failed surgery, the radiolunate articulation is enfsrmedad, in which case a salvage procedure is required.