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Evaluation of Computed Tomography Osteoabsorptiometry in Detection of Hip Dysplasia in Labrador Retrievers

Grimm, Patrick Joseph
http://rave.ohiolink.edu/etdc/view?acc_num=osu1274460902

Abstract Details

2010, Master of Science, Ohio State University, Veterinary Clinical Sciences.
Canine hip dysplasia is a chronic, debilitating developmental condition where incongruity of the coxofemoral joint often results in osteoarthrosis. Multiple radiographic methods for assessment of hip dysplasia are available, however can be limited in their capability to reliably diagnose hip dysplasia within juvenile dogs. As a new approach to the understanding of the pathologic processes and potential for earlier diagnosis of canine hip dysplasia, our objective was to determine if acetabular and femoral subchondral bone density (SBD) changes can be detected within normal and dysplastic coxofemoral joints using CT osteoabsorptiometry at 6 months of age. Thirty-three Labrador Retrievers from the U.S. Department of Defense Military Working Dog Breeding Program were diagnosed with normal or dysplastic coxofemoral joints based on computed radiographic pelvic studies by a consensus of 3 board-certified radiologists using the OFA evaluation grades at 6, 12, 18, and/or 24 months of age. Helical pelvic CT studies at 6 months of age were obtained with the patient in dorsolateral subluxation positioning (3.0 mm slice thickness, bone algorithm). A calcium hydroxyapatite calibration phantom was placed into the field of view of every study to standardize and allow conversion of all Hounsfield Unit values to Calcium Hydroxyapatite Equivalent Density units (CHED, mg/ml). CT data was converted into 3D reconstructions for volumetric assessment of SBD along the load-bearing regions of the femoral heads and acetabula 2 mm beneath their articular margins. Color mineral density distribution patterns were generated by assigning a color scale to the calculated density values. Nine standardized ROI were made within the load-bearing regions of the acetabula (n = 3) and femoral heads (n = 6). Descriptive statistics and a mixed model repeated measures ANOVA with associated partial correlation coefficients were used to evaluate the mean CHED values of ROI between dogs of the same and differing OFA radiographic classifications. Significance was set at P < 0.05. Seventeen, 11, and 5 dogs were diagnosed with bilaterally normal, bilaterally dysplastic, or unilaterally dysplastic coxofemoral joints, respectively. Strong correlations were present between all mean CHED values of the ROI within bilaterally normal and dysplastic dogs except for two (caudodorsal aspect of the acetabulum and craniolateral aspect of the femoral heads), which had moderate to weak correlations (r = 0.47 and 0.56, respectively). Bilaterally dysplastic dogs had a significant decrease (P < 0.01) in mean CHED ROI values along the caudodorsal aspect of the acetabulum (484.16 mg/ml) and craniolateral aspect of the femoral heads (350.03 mg/ml) when compared with bilaterally normal dogs (533.14 mg/ml and 404.74 mg/ml, respectively). The decrease in mean SBD within the dysplastic joints is likely attributed to decreased distribution of load bearing forces through these regions of the incongruent and/or subluxated joints in accordance with Wolff’s Law. A concurrent increase in mean SBD was not seen in the other ROI as expected, which may be attributed to degree of severity of disease, study limitations (sample size and volume averaging), or age at time of imaging.
Wm Tod Drost, Dr. (Advisor)
Matthew Allen, Dr. (Committee Member)
Eric Green, Dr. (Committee Member)
66 p.
Veterinary Services
dog; canine; pelvis; coxofemoral; Wolff's Law

Recommended Citations

Citations

  • Grimm, P. J. (2010). Evaluation of Computed Tomography Osteoabsorptiometry in Detection of Hip Dysplasia in Labrador Retrievers [Master's thesis, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1274460902

    APA Style (7th edition)

  • Grimm, Patrick. Evaluation of Computed Tomography Osteoabsorptiometry in Detection of Hip Dysplasia in Labrador Retrievers. 2010. Ohio State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1274460902.

    MLA Style (8th edition)

  • Grimm, Patrick. "Evaluation of Computed Tomography Osteoabsorptiometry in Detection of Hip Dysplasia in Labrador Retrievers." Master's thesis, Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1274460902

    Chicago Manual of Style (17th edition)

osu1274460902
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This open access ETD is published by The Ohio State University and OhioLINK.