Bone mineral density after spinal cord injury: a reliable method for knee measurement.
OBJECTIVE
To test the interrater reliability of a standardized method to analyze knee bone mineral density (BMD) using dual-energy x-ray absorptiometry (DXA); to compare spine, hip, and knee BMD of people with spinal cord injury (SCI) with able-bodied controls; and to determine the relation between hip BMD and knee BMD in SCI and able-bodied subjects.


METHODS
Criterion standard and masked comparison.


METHODS
Primary care university hospital.


METHODS
A convenience sample of 11 subjects with complete SCI was age and sex matched with 11 able-bodied control subjects.


METHODS
Not applicable.


METHODS
Four raters analyzed regions of interest according to operational definitions recently developed to standardize the analysis of BMD of the knee. Subjects with chronic SCI and matched controls underwent conventional DXA scans of the spine and hips and "less conventional" scans of the distal femurs and proximal tibias. The relation between hip and knee BMD was analyzed.


RESULTS
The knee measurements were highly reliable (femur intraclass correlation coefficient model 2,1 [ICC(2,1)]=.98; tibia ICC(2,1)=.89). Subjects with SCI had lower BMD values than controls at all hip and knee sites (P<.05). Lumbar spine BMD did not differ between groups. Hip BMD was moderately predictive of distal femur BMD (R2=.67), but less correlated with the proximal tibia (R2=.38).


CONCLUSIONS
Knee BMD can be reliably analyzed using DXA with this protocol. Subjects with SCI have diminished knee and hip BMD. Low hip BMD is associated with low distal femur BMD.
Shields
Richard K
RK
Graduate Program in Physical Therapy and Rehabilitation Science, Carver College of Medicine, University of Iowa, Iowa City, IA 52242-1190, USA. richard-shields@uiowa.edu
Schlechte
Janet
J
Dudley-Javoroski
Shauna
S
Zwart
Bradley D
BD
Clark
Steven D
SD
Grant
Susan A
SA
Mattiace
Vicki M
VM
D015502:Absorptiometry, Photon; D000328:Adult; D000368:Aged; D015519:Bone Density / Q000502:physiology*; D016022:Case-Control Studies; D005260:Female; D005269:Femur / Q000000981:diagnostic imaging / Q000503:physiopathology*; D006615:Hip / Q000000981:diagnostic imaging / Q000503:physiopathology; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging / Q000503:physiopathology*; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D013119:Spinal Cord Injuries / Q000503:physiopathology*; D013131:Spine / Q000000981:diagnostic imaging / Q000503:physiopathology; D013977:Tibia / Q000000981:diagnostic imaging / Q000503:physiopathology*