the etiology of kienbock 's disease , also 
 known as ( osteonecrosis of the lunate , remains 
 controversial .
it commonly occurs in patients 
 twenty to fourty years old and presents with pain 
 and stiffness in the dorsomedial aspect of the wrist . 

several risk factors have been established to help 
 explain its etiology : acute or repetitive trauma , 
 variation in blood supply to the lunate , differences 
 in the anatomy and shape of the lunate bone , and 
 venous congestion ( 1 , 2 ) . abnormal biomechanics 
 at the radiocarpal joint between the distal radius 
 and ulna has also been implicated in kienbock 's 
 disease ( 3 , 4 ) .
ulnar variance describes the length 
 relationship between the articular surfaces of the 
 radius and ulna at the radiocarpal joint .
positive 
 ulnar variance indicates that the ulna is longer than 
 the radius , while negative ulnar variance indicates 
 that the ulna is shorter at the wrist joint . in neutral 
 ulnar variance 80% of the axial load at the wrist 

is transmitted through the distal radius . as ulnar 
 variance decreases to more negative values , the load transmission across the distal radiocarpal 
 joint increases , subsequently exposing the lunate 
 to abnormally higher pressures and potentially 
 increasing the risk of kienbock 's disease ( 3 , 4 ) .
kienbock 's disease is also associated 
 with systemic lupus erythematosus ( sle ) ( 5 - 8 ) , 
 antiphospholipid antibody syndrome ( 9 ) , sickle 
 cell anemia ( 10 ) , and crohn 's enteritis ( 11 ) . 
 multiple hereditary osteochondromata ( 12 ) , carpal 
 coalition ( 13 , 14 ) and congenital shortening of the 
 ulna in langer - giedion syndrome ( 15 ) , are other 
 anatomic abnormalities that have been reported 
 with kienbock 's disease .
rheumatic diseases , 
 including scleroderma ( 16 - 18 ) , rheumatoid arthritis 
 ( 19 ) , gout ( 20 , 21 ) and dermatomyositis ( 22 ) have 
 been published in association with kienbock 's , but 
 there have been no identifiable cases in patients 
 with juvenile idiopathic arthritis ( jia ) .
this report presents a case of 
 osteonecrosis of the lunate in a patient with jia and 
 no prior history of trauma .
furthermore , a literature 
 review is done to illustrate the proposed etiologies 
 of kienbock 's disease and its association with other 
 rheumatologic conditions .
a 20-year - old right - handed female with 
 known rheumatoid factor negative polyarticular jia 
 presented to the clinic because of pain and limited 
 range of motion in the left wrist .
she was diagnosed with jia at the age of 
 nine after a two - month history of pain and swelling 
 in both hands and knees .
during the course of her 
 illness several other joints progressively became 
 involved . during the first year of treatment , she 
 was prescribed nonsteroidal anti - inflammatory 
 medication and low - dose prednisolone . to help 
 control her symptoms she required diseasemodifying 
 antirheumatic drugs .
her medications 
 included methotrexate 20 mg weekly , folinic acid 
 2.5 mg weekly , and etanercept 25 mg twice a week .
three weeks prior to presentation , the 
 patient experienced a severe flare of her arthritis 
 due to non - compliance with her medication .
this 
 lead to persistent left wrist pain and limited rangeof- 
 motion . on examination she demonstrated 
 synovial thickening of her left wrist with no palpable 
 effusion .
magnetic resonance imaging of her left 
 wrist showed mild synovial thickening and erosive 
 arthropathy throughout the carpus , radiocarpal , 
 and carpometacarpal joints .
in addition , there 
 is possible sclerosis and edema , since she had collapse of the lunate with mixed signal 
 intensity .
plain radiographs revealed negative 
 ulnar variance , sclerosis , and loss of lunate height 
 ( fig .
the imaging was compatible with stage 4 
 osteonecrosis of the lunate ( 23 ) .
the patient was 
 managed non - operatively and at two - year follow - up 
 was asymptomatic with no concomitant worsening 
 of lunate osteonecrosis on radiograph .
a. coronal t1-weighted fast - spin - echo magnetic resonance image showing collapse of the lunate with mixed signal intensity 
 suggesting sclerosis and edema consistent with kienbock 's disease ( arrow ) .
b. antero - posterior plain x - ray of the left wrist demonstrates sclerosis and slight loss of height 
 involving the lunate compatible with kienbock 's disease ( arrow ) .
the current literature indicates that 
 most cases of kienbock 's disease develop without 
 a history of trauma and posit that e extraosseous 
 and intraosseous blood supply to the lunate have 
 a role in the disease process .
the extraosseous 
 blood supply is formed by a series of dorsal and 
 volar vascular arches ( 1 , 24 ) .
the intraosseous 
 blood supply is made up of braches entering the 
 volar and dorsal poles however the composite of 
 this vasculature is variable ( 1 , 25 - 27 ) ; branches 
 demonstrate different anastomosis patterns inside 
 the lunate , or the lunate may be supplied by only one 
 dorsal or volar branch or by both a dorsal and volar 
 arterial supply the lunate without any anastomosis 
 ( 26 ) .
when an anastomosis does exist , it can be 
 characterized as a y , x , or i pattern , depending on 
 the amount of vessels supplying each pole ( 24 , 27 ) . 

depending on the intraosseous vascular anatomy of the lunate , certain lunate bones are predisposed 
 to kienbock 's disease .
this concept was highlighted 
 in a case report of kienbock 's disease associated 
 with sickle cell anemia ( 10 ) .
the osteonecrosis was 
 thought to have developed from an at - risk lunate - 
 single volar arterial supply - along with significant 
 vascular sickling and stasis .
pathogenesis of osteonecrosis of the lunate venous congestion has also been attributed 
 to the pathogenesis of kienbock 's disease ( 2 ) . 
 during surgery
, jensen measured increased 
 pressure inside the lunate compared with the radial 
 styloid and capitate .
he concluded that the higher 
 pressure was caused by venous congestion leading 
 to osteonecrosis of the lunate .
negative ulnar variance is also implicated 
 in the pathogenesis of kienbock 's disease ( 3 , 4 , 
 28 ) .
the altered relationship between the ulna 
 and radius at the distal radioulnar joint modifies 
 the biomechanics at the radiolunate joint and 
 increases strains on the lunate .
this postulation 
 is still controversial because several studies , 
 including a meta - analysis , have shown that 
 negative ulnar variance is not a risk factor for 
 developing kienbock 's disease , ( 29 , 30 ) . on the 
 contrary , ledoux et al .
performed a finite - element 
 analysis on cadaveric lunate bones and found 
 that the progression of a fracture of the lunate was 
 present with negative ulnar variance , a high lunate 
 uncovering index , which is the amount of lunate 
 outside the lunate fossa of the radius compared 
 to the amount of lunate articulating with the 
 lunate fossa , and angulated trabeculae ( 31 ) .
this 
 suggests that given the circumstance , the lunate 
 can be at risk for developing osteonecrosis due to 
 abnormal stresses .
further cases have also reportedpatients with 
 conditions that may have caused altered stresses 
 on the lunate .
in particular , two cases have been 
 reported involving carpal coalition ( 13 , 14 ) .
it was postulated in these cases that carpal coalition 
 caused a progressively increasing stress on the 
 lunate , which in turn led to kienbock 's disease . 

schuind et al . reported a case of kienbock 's 
 disease associated with congenital shortening of 
 the ulna as seen in langer - giedion syndrome 
 ( 15 ) .
it was suggested that kienbock 's disease 
 developed from microfractures sustained by 
 an abnormal stress distribution ( 15 ) .
multiple 
 hereditary osteochondromata in the forearm was 
 also found in association with kienbock 's disease 
 and was attributed to an excess load on the lunate 
 by negative ulnar variance , but with no carpal slip 
 ( 12 ) .
systemic lupus erythematosus has been 
 associated with avascular necrosis of bone . in 
 1977 , urman presented several cases of patients 
 with sle and osteonecrosis of the carpal bones , 
 including a case report of a patient with sle and 
 kienbock 's disease ( 8) . the patient also had a history 
 of raynaud 's phenomenon and was taking highdose 
 corticosteroids . in sle patients
treated with 
 corticosteroids and who developed osteonecrosis , 
 there was one patient who developed kienbock 's 
 disease ( 5 ) .
this patient was treated with large 
 doses of corticosteroids compared to those who did 
 not develop kienbock 's disease .
mok et al . reported 
 a case of bilateral kienbock 's disease in a patient 
 with sle ( 6 ) .
the patient described in this case 
 report was never treated with corticosteroids and 
 the etiology of kienbock 's disease was thought to 
 be due to a vasculopathy caused by either vasculitis 
 or antiphospholipid antibodies , even though this 
 patient tested negative for lupus anticoagulant and 
 anticardiolipin antibodies .
more recently , taniguchi 
 et al . described two cases of kienbock 's disease 
 in sle after taking high doses of steroids ( 7 ) . 

one of the cases was of a patient who developed 
 bilateral osteonecrosis of the lunate .
it is apparent that the cases 
 of kienbock 's disease in patients with sle were 
 either attributed to high dose corticosteroid use 
 or to the disease itself .
more over , patients with 
 crohn 's disease who use corticosteroids to 
 control disease symptoms are known to develop 
 kienbock 's disease and osteonecrosis of the 
 hip ( 11 ) .
the same scenario also occurred in a 
 patient with dermatomyositis taking high doses of 
 corticosteroids for sixteen months ( 22 ) .
scleroderma associated with kienbock 's 
 disease was first reported by agus et al . in a patient 
 with bilateral osteonecrosis of the lunate ( 16 ) .
this 
 patient had severe raynaud 's phenomenon and was 
 never treated with corticosteroids .
the contributing 
 factors were hypothesized to be vasculopathy , 
 raynaud 's phenomenon , and a lunate consisting 
 of a single nutrient vessel .
ribbans also reported 
 a case of kienbock 's disease in a patient with 
 scleroderma and severe raynaud 's phenomenon 
 ( 18 ) .
the vasculopathy , scleroderma , and repeated 
 use of the patient 's affected wrist predisposed this 
 patient to kienbock 's disease .
matsumoto et al . 
 reported three cases of kienbock 's disease in three 
 patients with scleroderma , two without a history 
 of steroid use and one who only used low dose 
 steroids prior to the diagnosis of osteonecrosis ( 17 ) . 

all three patients also had limited skin involvement , 
 but had severe raynaud 's phenomenon .
they 
 reported that scleroderma related vascular disease 
 was likely the cause of the circulatory impairment 
 leading to osteonecrosis .
mok et al . reported a patient with 
 rheumatoid arthritis who was found to have 
 osteonecrosis of the lunate .
they believed that 
 the kienbock 's disease occurred in this patient due 
 to an increase in intra - articular pressure within the 
 wrist compartment , causing impedance of venous 
 return , vascular insufficiency to the lunate , and 
 subsequent osteonecrosis ( 19 ) .
in addition to the various risk factors 
 mentioned above , kienbock 's disease b is 
 prevalent in specific patient populations .
rooker 
 et al . found an increased prevalence of kienbock 's 
 disease in a group of patients with cerebral palsy 
 ( 9.4% ) ( 32 ) .
this was thought to be related to an 
 abnormally flexed posture of a spastic wrist , which 
 was present in all patients with kienbock 's disease 
 in this study and could impede blood flow .
. 
 also found an increased prevalence of kienbock 's 
 disease in patients with cerebral palsy ( 2.7% ) ( 33 ) . 

they believed that the high muscle tone across the 
 wrist in an ulnar negative wrist caused an increased 
 pressure on the lunate .
this cause is consistent 
 with repeated microtrauma leading to vascular 
 compromise and ultimately osteonecrosis .
while the association between kienbock 's 
 disease and several of the reported cases could 
 be coincidental , having a rheumatologic comorbidity 
 such as jia could represent a risk factor for kienbock 's disease , as seen in the presented 
 case report .
the wrist is the second most common 
 site of growth abnormality in patients with jia 
 ( 34 ) .
several changes occur at the wrist , including 
 narrowing of the intercarpal spaces , premature 
 ossification of the carpal bones , and early fusion 
 of the ulnar epiphysis leading to a shorter ulna 
 ( negative ulnar variance ) ( 35 ) .
the wrist ultimately 
 becomes displaced ulnarly and volarly leading to 
 a dislocation of the wrist and bayonet deformity . 

therefore , it is possible that the abnormalities 
 in the wrist associated with jia could lead to 
 abnormal stresses and or pressures in the wrist 
 that led to kienbock 's disease .
furthermore , the 
 erosive changes in other carpal bones may lead 
 to a change on the normal force patterns in the 
 patient 's carpus .
seven years prior to the onset 
 of kienbock 's disease , our patient was also treated 
 with low - dose corticosteroids which could have also 
 disrupted circulation and led to the development of 
 lunate osteonecrosis .
several theories attempt to 
 explain its pathogenesis , which suggests that it 
 may be multifactorial .
many risk factors have also 
 been identified ; steroid treatment , a predisposing 
 rheumatologic disease , a variation in lunate blood 
 supply , and possibly negative ulnar variance .
it also suggests that 
 kienbock 's disease could be a possible cause of 
 wrist pain and stiffness in patients with jia .
 kienbock 's disease or osteonecrosis of the lunate is an uncommon 
 cause of wrist pain . . 
 though there have been several reports of cases in patients 
 with various rheumatologic diseases , the precise etiology has currently not been 
 established . 
 we report a case of kienbock 's disease that occurred in a patient with 
 juvenile idiopathic arthritis . to our knowledge 
 , this is the first case report with an 
 association between these two conditions . 
INTRODUCTION
CASE REPORT
DISCUSSION