A reliable method for measuring proximal tibia and distal femur bone mineral density using dual-energy X-ray absorptiometry.
OBJECTIVE
To assess the intra- and inter-rater reliability of a standardized protocol for measuring proximal tibia and distal femur bone mineral density (BMD) using dual-energy X-ray absorptiometry (DXA).


METHODS
Ten able-bodied individuals (7 males) participated in this study. During one measurement session, the knee of each participant was scanned twice by rater 1 using DXA. Both scans were analyzed twice by rater 1 as well as once by a second rater. Intraclass correlation coefficients (ICCs), standard error of measurements (SEMs) and smallest detectable differences (SDDs) were calculated for the outcome measures proximal tibia and distal femur BMD. A decision study was performed to determine the effect of study protocol adjustments (i.e. increasing the number of scan repetitions, or scan analyses by the same rater) on SEM and SDD values.


RESULTS
High intra- and inter-rater ICCs (0.97-0.98) were found for both proximal tibia and distal femur BMD. Low SEMs (0.017-0.028 g/cm(2)) and SDDs (0.047-0.077 g/cm(2)) were found, with a slightly better result for proximal tibia BMD. Increasing the number of scan analyses by the same rater did not markedly reduce SEM and SDD values, while increasing the number of scan repetitions did.


CONCLUSIONS
Proximal tibia and distal femur BMD can be reliably assessed with this method.
Research Institute MOVE, Faculty of Human Movement Sciences, VU University Amsterdam, The Netherlands; Amsterdam Rehabilitation Research Center | Reade, Amsterdam, The Netherlands. Electronic address: a.j.t.bakkum@vu.nl.
Arjan J T
AJ
Bakkum
Research Institute MOVE, Faculty of Human Movement Sciences, VU University Amsterdam, The Netherlands; Amsterdam Rehabilitation Research Center | Reade, Amsterdam, The Netherlands.
Thomas W J
TW
Janssen
Department of Physics and Medical Technology, VU University Medical Center Amsterdam, The Netherlands.
Marijn P
MP
Rolf
Department of Radiology, VU University Medical Center Amsterdam, The Netherlands.
Jan C
JC
Roos
Department of Radiology, VU University Medical Center Amsterdam, The Netherlands.
Jos
J
Burcksen
Department of Epidemiology and Biostatistics, VU University Medical Center Amsterdam, The Netherlands.
Dirk L
DL
Knol
Amsterdam Rehabilitation Research Center | Reade, Amsterdam, The Netherlands; University of Groningen, University Medical Centre Groningen, Center for Human Movement Sciences, The Netherlands.
Sonja
S
de Groot
D015502:Absorptiometry, Photon / Q000295:instrumentation / Q000379:methods*; D000328:Adult; D015519:Bone Density; D005260:Female; D005269:Femur / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D013977:Tibia / Q000502:physiology*
Bone mineral density; Distal femur; Dual-energy X-ray absorptiometry; Generalizability theory; Intra- and inter-rater reliability; Osteoporosis; Proximal tibia; Spinal cord injury