ALBERTO SALVAGGIO

ANTONELLA VOLTA

DINI, Fabrizio

GIACOMO GNUDI

PALUMBO PICCIONELLO, Angela

SABRINA MANFREDI

TAMBELLA, Adolfo Maria

English

Archivio istituzionale della ricerca - Università di Camerino

4'5 • 16d'ESVOT Congress 2012, Bologna (Italy), 12° 1 - 15'h September Palarabo Piccionello Effect of pelvic positioning and torsional deformity on canine acetabular morphology with computed tomography: a phantom study A. Volta, DVM, PhD, Assistant Professor', A. Salvaggio,Dvm2, A. Palumbo Piccionello,  DVM, PhD, Assistant Professor 2 , F. Dtni, DVM, Assistant Professor 2, S. Manfredi, Dial, PhD', A.M. Tambella, DVM, Assistant Professor2, G. Gnudi, DVII, PhD, Associate Professor' L SeniAleda Radiologia e Diagnostica per Inoragrini, Rag di itledicina PIerinaria, Anna, Paha 2 &tione ado, Scuola di Sciente Mediche VeWrinarie, Maklica, Italia INTRODUCTION Aretabular retroversion is widely described in humans as a cause of hip osteoarthritis and recently reported in dogs. Acetabular retroversion in dogs should be called "dorscrversion" for anatomic differences in the pos-ture. In a recent study extraroration of the hemipelvis on its long axis and the presence of the cross over sign (COS) were common features in a series of English Bulldogs with hip abnormalities. Pelvic inclination has been proved in humans and dogs to have a direct influence on the acetabular version appearance. H a pelvis is excessively reclinated (ischia far from the cassette, ilia near the cassette), the ac-etabular cup version seems more anteverted than it actually is. In an excessively inclinated pelvis (ilia far from the cassette, Ischia near the cassette), the acetabular cup version seems more retroverted than it actu-ally is. There is no standard protocol describing CT patient positioning, slice thickness and slice selection for acetabular angles computations. The effects of patient positioning and slice selection on acetabular an-gles have been assessed by a relatively recent report. The purpose of this study was to evaluate with CT how the inclination and extrarotation of the hemipelvis affect acetabular angle (AA) and dorsal acetabular rim angle (DARA) assessment, MATERIALS AND METHODS A 16-slice multidetector CT scanner (LightSpeed 16, GE Healthcare) was used., with a slice thickness of mm. A normal canine hemipelvis was put in a specially designed holding device in dorsal recumbency. It was scanned with different degrees of extrarotation on its long axis (0', 5', 10°, 15'). Each degree of EX-uaroLation was acquired at CP, +20P, -20P of gantry tilt in order to mimic respectively a horizontal, indihrat-ed and reclinated pelvis. Individual acetabular angles !IAA! were calculated in the cranial acetabulum (3rd slice from the beginning of the acetabulum) and central acetabulum (12th slice from the beginning of the K-etabulurn.). Dorsal acetabular rim angles (DARAI were calculated in the central acetabulum (12th slice from the beginning of the acetabulum). Both IAA and DARA were calculated for each degree of extrarotation and gantry tilt. Pearson's correlation coefficients were calculated between acetabular angles, inclination and extrarotation of the hemipelvis. Correlation was judged very strong if the correlation coefficient was at least 0.8, moderately strong if the correlation coefficient was 0.6 up to 0.8, fair if the correlation coefficient was 0.3 up to 0.5 and poor if the correlation coefficient was less than 0.3. Dorsoversion of the acetabulum was present on CT images if the ventral acetabular rim was laterally to the dorsal rim. RESULTS A strong negative correlation was found between cranial and central IAA and pelvic inclination for each de-gree of extrarotation. A strong negative correlation was found between cranial and central IAA and pelvic extrarotation for each degree of inclination. There was a strong positive correlation between DARA and pelvic inclination for each degree of extrarotation and a strong positive correlation between DARA and pelvic extrarotation for each degree of inclination. Dorsoversion of the acetabulum was present on Cr im-ages when the hemipelvis was 10° and 15° extrarotated and +20' inclinated. CONCLUSION In dogs OT is used to assess joint changes after pubic symphysiodesis and to detect joint laxity and carti-lage damage for the diagnosis of hip dysplasia. Patient positioning is not standardized. Some authors place the dogs in dorsal recumbency and others in ventral recumbency. This could lead to different pelvic posi-tioning relative to the scanning plane. Dorsal recumbency could mimic an inclinated pelvis, while ventral re- A Paiumbo PSaione llo 16 1 bESVOT Congress 2012, Bologna (Italy), 12 113 - 15a September • 476 cumbency a reclinated pelvic. This has been demonstrated to have a direct effect on the acetabular mor-phology both in CT images and on radiographs. In reclinated pelvis the acetabular coverage is overesti-mated, while in inclinated pelvis the acetabular coverage in underesdmated. In this report acetabular angles ',IAA and DARAI resulted affected by pelvic positioning in the way that the more the pelvic inclination the less the IAA and the more the DARA. As a result of this the more the inclination of the pelvis the worse the morphology of the acetabulurn. In case of a redihated pelvis, the slice cut involves a more cranial portion of the dorsal acetabular rim than in case of an inclinated pelvis. Moreover in a reclinated pelvis the slice cut involves the acetabular fossa. This is in agreement with the results of a recent report in which the AA dif-fered significantly with small differences of pelvic tat, Acetabular and pelvic torsional deformities associated with hip osteoarthritis are described in humans and recently reported in dogs. In dogs this pelvic abnor-mality is not well known. In this study IAA and DARA were affected by ectrarotation of the pelvis (under-stood as torsional deformity) in the way that the more the extrasoration, the less the IAA and the more the DARA. As a result of this more the extrarotation, the worse the morphology of the acetabulum. E_xternal rotation of the hemipelvis on its long axis leads to a reduction of the dorsal acetabular coverage and pre-disposes to femoral head sublwsadon and could worsen joint instability. Dorsoversion of the acetabulum was seen only when the pelvis was inclinated. This points out that dorsoversion is dependent on the slice cut plane and on the positioning of the patient, as it is the CADS on the radiographs. In conclusion, torsional de-formities and pelvic positioning affect acetabular morphology on RX and CT images; so it would be nec-essary consider those variables to avoid mistakes in the evaluation of the acetabular cover. Three-dimension volume rendering of the acetabulum could be very useful in this case because it is independent of the scan-ning plane. On the other hand computations on 3D images are difficult and for this reason a standardised CT scanning protocol is needed to avoid misjudgement of acetabular angles and acetabular morphology. A proper scanning protocol should include standard slice thickness and slice selection for acetabular angles computation and it should consider pelvic inclination. The actual relevance of pelvic torsional deformities and dorsoversion is not well documented in dogs. REFERENCES Ezoe M., Naito M., Inoue T. (2006). The prevalence of acetabular retroversion among various disorders of the hip. Jour-nal of Bone and Joint Surgery American Volume 88, 372-3701. Ciori Nj., Trousdale R.T.(200). Acetabular retroversion is as.sociated with osteoarthritis of the hip Clinical  Or-thopaedics and Related Reaearch 417, 262-260. Loper MJ., Lewis S.F., Swaab M.E., Markel M.D. (2008). Relationships among measurements obtained by use of com-puted tomography and radiography and scores of cartilage microdamage in hip joints with moderate to severe joint laxity of adult dogs. American Journal of "Veterinary Research 60, 362-70. Parei.raA.C., Hunter J.C., Laird T., jamali A_A. (2011). Multilevel measurement of acetabular version using 3-D CT-gm- crated models: implications for hip preservation surgery. Clinical Orthopaedics and Related Research 46g, 352-561. Sieabnxk K.A., Kalamai ten D.P., Ganz R. 02002) Effect on pelvic tilt on acetabular retroversion; a study of pelves from cadavers. Clinical Orthopaedics and Related Research 40Z 241-248. Volta A. Crnicli C, Morgan J .P., Bonin M., Manfredi S., Bottarelli E., Zanichelli S., Berroni C. polo). Radicgraphic fea-tures of pelvis and hip joint development of English Bulldogs. Veterinary Comparative Orthopaedics and Trauma-tolcgy 23, 10-27. Wang S.I., Mathews K.C., Rob enson I.D., Stebbins M., Trumpatori BJ. (2003). The effects of patient positioning and slice selection on canine acetabular angle assessment with computed tomography. Veterinary Radiology and LT1tra-sound 46, 30-4. Coexerpmdirrs Address: Dottaaa Angela Palumbo Piccionello - Scuola di Scienze Mediche ileterinarie, Universita di Camerino, Circonvallazione (Pres.so FacoltS. M Veterinara) 92/05, 62024 Matelica (MC), ITALIA Tel. 07371403403 - Cell. 339i3361081 - E-mail. angelapalimboguni=1-i 

EFFECT OF PELVIC POSITIONING AND TORSIONAL DEFORMITY ON CANINE ACETABULAR MORPHOLOGY WITH COMPUTED TOMOGRAPHY: A PHANTOM STUDY

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EFFECT OF PELVIC POSITIONING AND TORSIONAL DEFORMITY ON CANINE ACETABULAR MORPHOLOGY WITH COMPUTED TOMOGRAPHY: A PHANTOM STUDY

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Archivio istituzionale della ricerca - Università di Camerino