PATIENT-SPECIFIC CUP ORIENTATION CAN BE ACHIEVED BY INTEGRATING THE COMBINED SAGITTAL INDEX, FURTHER MINIMIZING RISK OF DISLOCATION

Falsetto A, Sanders E, Weishorn J, et al. PATIENT-SPECIFIC CUP ORIENTATION CAN BE ACHIEVED BY INTEGRATING THE COMBINED SAGITTAL INDEX, FURTHER MINIMIZING RISK OF DISLOCATION. Orthop Procs. 2021;103-B(SUPP_10):37-37. doi:10.1302/1358-992X.2021.10.037

Falsetto, A, et al. “PATIENT-SPECIFIC CUP ORIENTATION CAN BE ACHIEVED BY INTEGRATING THE COMBINED SAGITTAL INDEX, FURTHER MINIMIZING RISK OF DISLOCATION.” Orthopaedic Proceedings, vol. 103-B, no. SUPP_10, 2021, pp. 37-37., https://doi.org/10.1302/1358-992X.2021.10.037

Falsetto, A., Sanders, E., Weishorn, J., Gill, H., McGoldrick, N., Beaulé, P., Innmann, M., Merle, C., & Grammatopoulos, G. (2021). PATIENT-SPECIFIC CUP ORIENTATION CAN BE ACHIEVED BY INTEGRATING THE COMBINED SAGITTAL INDEX, FURTHER MINIMIZING RISK OF DISLOCATION. Orthopaedic Proceedings, 103-B(SUPP_10), 37-37. https://doi.org/10.1302/1358-992X.2021.10.037

Falsetto, A., Sanders, E., Weishorn, J., Gill, H., McGoldrick, N., Beaulé, P. et al. (2021) “PATIENT-SPECIFIC CUP ORIENTATION CAN BE ACHIEVED BY INTEGRATING THE COMBINED SAGITTAL INDEX, FURTHER MINIMIZING RISK OF DISLOCATION.” Orthopaedic Proceedings, 103-B(SUPP_10), pp. 37-37. Available at: https://doi.org/10.1302/1358-992X.2021.10.037

Falsetto, A, E Sanders, J Weishorn, H Gill, N McGoldrick, P Beaulé, M Innmann, C Merle, and G Grammatopoulos. “PATIENT-SPECIFIC CUP ORIENTATION CAN BE ACHIEVED BY INTEGRATING THE COMBINED SAGITTAL INDEX, FURTHER MINIMIZING RISK OF DISLOCATION.” Orthopaedic Proceedings 103-B, no. SUPP_10 (2021): 37-37. https://doi.org/10.1302/1358-992X.2021.10.037

Falsetto A, Sanders E, Weishorn J, Gill H, McGoldrick N, Beaulé P, et al. PATIENT-SPECIFIC CUP ORIENTATION CAN BE ACHIEVED BY INTEGRATING THE COMBINED SAGITTAL INDEX, FURTHER MINIMIZING RISK OF DISLOCATION. Orthop Procs. 2021 Aug 1;103-B(SUPP_10):37-37. https://doi.org/10.1302/1358-992X.2021.10.037

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Abstract

This matched cohort study aims to (a) assess differences in spinopelvic characteristics of patients having sustained a dislocation following THA and a control THA group without dislocation; (b) identify spinopelvic characteristics associated with risk of dislocation and; (c) propose an algorithm to define the optimum cup orientation for minimizing dislocation risk.

Fifty patients with a history of THA dislocation (29 posterior-, 21 anterior dislocations) were matched for age, gender, body mass index, index diagnosis, and femoral head size with 100 controls. All patients were reviewed and underwent detailed quasi-static radiographic evaluations of the coronal- (offset; center-of-rotation; cup inclination/anteversion) and sagittal- reconstructions (pelvic tilt, pelvic incidence, lumbar lordosis, pelvic-femoral-angle, cup ante-inclination). The spinopelvic balance (PI-LL), combined sagittal index (CSI= Pelvic-femoral-angle + Cup Anteinclination) and Hip-User-Index were determined. sagittal index (CSI= Pelvic-femoral-angle + Cup Anteinclination) and Hip-User-Index were determined. Parameters were compared between the two groups (2-group analysis) and between controls and per direction of dislocation (3-group analysis).

There were marginal coronal differences between the groups. Sagittal parameters (lumbar-lordosis, pelvic-tilt, CSI, PI-LL and Hip-User-Index) differed significantly. PI-LL (>10°) and standing pelvic tilt (>18°) were the strongest predictors of dislocation risk (sensistivity:70%/specificity:70%). All hips with a standing CSI<195° dislocated posteriorly and all with CSI>260° dislocated anteriorly. A CSI between 200–245° was associated with significantly reduced risk of dislocation (OR:6; 95%CI:2.5–15.0; p<0.001). In patients with unbalanced and/or rigid lumbar spine, standing CSI of 215–245° was associated with significantly reduced dislocation risk (OR:10; 95%CI:3.2–29.8; p<0.001).

PI-LL and standing pelvic-tilt determined from pre-operative, standing, lateral spinopelvic radiograph can be useful screening tools, alerting surgeons of patients at increased dislocation risk. Measurement of the pelvic-femoral angle pre-operatively provides valuable information to determine the optimum, cup orientation associated with reduced dislocation risk by aiming for a standing CSI of 200–245°.

Email: ggrammatopoulos@toh.ca