N.N. Priorov Journal of Traumatology and OrthopedicsN.N. Priorov Journal of Traumatology and OrthopedicsВестник травматологии и ортопедии им. Н.Н. Приорова0869-86782658-6738Eco-Vector67859410.17816/vto678594TZXZKBOriginal study articlesОригинальные исследованияResearch ArticleHow unattended lateral pelvic tilt during total hip arthroplasty will affect acetabular cup inclination angle, a simplified demonstration on a sawbone pelvis modelКак некорригированный латеральный наклон таза при тотальном эндопротезировании тазобедренного сустава влияет на угол наклона вертлужного компонента: упрощённая демонстрация на модели таза Sawbonehttps://orcid.org/0000-0002-0710-6487KhalifaAhmed A.ХалифаАхмед Адель
Egypt

MD, FRCS, MSc., Assistant Professor, South Valley University Hospital

магистр, доцент, Университетская больница

ahmed_adel0391@med.svu.edu.egSouth Valley UniversityУниверситет Южной долины25122025310520263322712781504202523062025Copyright ©; 2026, Eco-VectorCopyright ©; 2026, Эко-Вектор2026Eco-VectorЭко-Векторhttps://creativecommons.org/licenses/by-nc-nd/4.0/https://journals.eco-vector.com/0869-8678/article/view/678594

BACKGROUND: Proper acetabular cup positioning, including inclination angle, affects long-term outcomes and total hip arthroplasty (THA) survival.

AIM: This experiment aims to explain how unattended lateral pelvic tilt will affect the cup inclination angle during THA.

METHODS: A normal pelvis sawbone model was fixed to an operative table, an acetabular cup attached to its inserter was applied to the sawbone model acetabulum aiming at an inclination angle of 40° in relation to the floor level, while the pelvis was placed in three different positions, neutral where the line connecting the anterior superior iliac spine (ASIS) is perpendicular (90°) to the floor level, adduction and abduction where the angle is less (-10) and more (+10) than 90° respectively. Then, the cup inclination angle in relation to the interischial line was measured.

RESULTS: As the pelvis was in a neutral position, the final cup inclination angle was the same as the intended angle (40°). When the sawbone model was adducted, the resultant cup inclination was 10° more (50°) than the intended angle. While in pelvis abduction, the resultant cup inclination was 10° less (30°) than the intended angle. In both situations, the difference was equal to the amount of lateral pelvic tilt.

CONCLUSIONS: In this experiment, we proved the profound effect of unattended lateral pelvic tilt during THA after patient positioning and draping on the cup inclination angle.

Обоснование. Корректное позиционирование вертлужного компонента, включая угол его наклона, оказывает существенное влияние на отдалённые результаты и выживаемость эндопротеза при тотальном эндопротезировании тазобедренного сустава (ТЭТС).

Цель. Продемонстрировать, каким образом некорригированный латеральный наклон таза влияет на угол наклона вертлужного компонента во время выполнения ТЭТС.

Методы. Нормальная модель таза Sawbone была зафиксирована на операционном столе. Вертлужный компонент, закреплённый на инструменте для имплантации, устанавливался в вертлужную впадину модели таза с целевым углом наклона 40° относительно уровня пола. При этом таз последовательно размещали в трёх различных положениях: нейтральном — когда линия, соединяющая передние верхние подвздошные ости, была перпендикулярна полу (90°); приведении — при угле менее 90° (–10°); и отведении — при угле более 90° (+10°). После этого измеряли фактический угол наклона компонента относительно межседалищной линии.

Результаты. При нейтральном положении таза итоговый угол наклона вертлужного компонента соответствовал запланированному (40°). При приведении модели таза результирующий угол наклона компонента увеличивался на 10° и достигал 50°. При отведении таза угол наклона, напротив, уменьшался на 10° и составлял 30°. В обоих случаях величина отклонения угла наклона компонента была равна величине латерального наклона таза.

Заключение. В данном эксперименте продемонстрировано выраженное влияние некорригированного латерального наклона таза во время ТЭТС, сохраняющегося после позиционирования пациента и операционного укрывания, на итоговый угол наклона вертлужного компонента.

total hip arthroplastytotal hip replacementacetabular cup placementpelvic tiltтотальное эндопротезирование тазобедренного суставатотальная замена тазобедренного суставаустановка вертлужного компонентанаклон тазаKanazawa M, Nakashima Y, Ohishi M, et al. Pelvic tilt and movement during total hip arthroplasty in the lateral decubitus position. Mod Rheumatol. 2016;26(3):435–40. doi: 10.3109/14397595.2015.1092914Ning D, Xu F, Zhang Z, Yang X, Wei J. Application of transverse acetabular ligament in total hip arthroplasty: a systematic review. BMC Musculoskelet Disord. 2023;24(1):284. doi: 10.1186/s12891-023-06410-0Sicat CS, Buchalter DB, Luthringer TA, Schwarzkopf R, Vigdorchik JM. Intraoperative Technology Use Improves Accuracy of Functional Safe Zone Targeting in Total Hip Arthroplasty. J Arthroplasty. 2022;37(7S):S540-S5. doi: 10.1016/j.arth.2022.02.038Abdel MP, von Roth P, Jennings MT, Hanssen AD, Pagnano MW. What Safe Zone? The Vast Majority of Dislocated THAs Are Within the Lewinnek Safe Zone for Acetabular Component Position. Clin Orthop Relat Res. 2016;474(2):386–91. doi: 10.1007/s11999-015-4432-5Meermans G, Grammatopoulos G, Innmann M, Beverland D. Cup placement in primary total hip arthroplasty: how to get it right without navigation or robotics. EFORT Open Rev. 2022;7(6):365–74. doi: 10.1530/EOR-22-0025Al-Shaer WM, Al-Yami AH, Al-Sayed MA, et al. Early results of primary total hip arthroplasty performed in young adults at a regional Saudi-Arabian orthopedics center: a prospective observational study. Traumatology and Orthopedics of Russia. 2024;30(4):38–46. doi: 10.17816/2311-2905-17570Rutherford M, O’Connor JD, Hill JC, et al. Patient positioning and cup orientation during total hip arthroplasty: assessment of current UK practice. Hip Int. 2019;29(1):89–95. doi: 10.1177/1120700018760818van Duren BH, Royeca JM, Cunningham CM, et al. Can the use of an inclinometer improve acetabular cup inclination in total hip arthroplasty? A review of the literature. Hip Int. 2021;31(5):609–17. doi: 10.1177/1120700020946716Sai Sathikumar A, Jacob G, Thomas AB, Varghese J, Menon V. Acetabular cup positioning in primary routine total hip arthroplasty — a review of current concepts and technologies. Arthroplasty. 2023;5(1):59. doi: 10.1186/s42836-023-00213-3Grammatopoulos G, Innmann M, Phan P, Bodner R, Meermans G. Spinopelvic challenges in primary total hip arthroplasty. EFORT Open Rev. 2023;8(5):298–312. doi: 10.1530/EOR-23-0049Louette S, Wignall A, Pandit H. Spinopelvic Relationship and Its Impact on Total Hip Arthroplasty. Arthroplast Today. 2022;17:87–93. doi: 10.1016/j.artd.2022.07.001Duval-Beaupere G, Schmidt C, Cosson P. A Barycentremetric study of the sagittal shape of spine and pelvis: the conditions required for an economic standing position. Ann Biomed Eng. 1992;20(4):451–62. doi: 10.1007/BF02368136Heckmann N, Trasolini NA, Stefl M, Dorr L. The Effect of Spinopelvic Motion on Implant Positioning and Hip Stability Using the Functional Safe Zone of THR. In: Riviere C, Vendittoli PA, editors. Personalized Hip and Knee Joint Replacement. Cham (CH): Springer International Publishing; 2020: 133–42.Snijders TE, Schlosser TPC, van Stralen M, et al. The Effect of Postural Pelvic Dynamics on the Three-dimensional Orientation of the Acetabular Cup in THA Is Patient Specific. Clin Orthop Relat Res. 2021;479(3):561–71. doi: 10.1097/CORR.0000000000001489DiGioia AM, Hafez MA, Jaramaz B, Levison TJ, Moody JE. Functional pelvic orientation measured from lateral standing and sitting radiographs. Clin Orthop Relat Res. 2006;453:272–6. doi: 10.1097/01.blo.0000238862.92356.45Okutani Y, Kataoka M, Harada H, et al. A high body mass index tilts the pelvis caudally in the lateral decubitus position for total hip arthroplasty. Hip Int. 2023;33(3):371–6. doi: 10.1177/11207000221084627Lewinnek GE, Lewis JL, Tarr R, Compere CL, Zimmerman JR. Dislocations after total hip-replacement arthroplasties. J Bone Joint Surg Am. 1978;60(2):217–20.Jolles BM, Zangger P, Leyvraz PF. Factors predisposing to dislocation after primary total hip arthroplasty: a multivariate analysis. J Arthroplasty. 2002;17(3):282–8. doi: 10.1054/arth.2002.30286Bosker BH, Verheyen CC, Horstmann WG, Tulp NJ. Poor accuracy of freehand cup positioning during total hip arthroplasty. Arch Orthop Trauma Surg. 2007;127(5):375–9. doi: 10.1007/s00402-007-0294-yHoskins W, Rainbird S, Lorimer M, Graves SE, Bingham R. What Can We Learn From Surgeons Who Perform THA and TKA and Have the Lowest Revision Rates? A Study from the Australian Orthopaedic Association National Joint Replacement Registry. Clin Orthop Relat Res. 2022;480(3):464–81. doi: 10.1097/CORR.0000000000002007Luu K, Nishioka ST, Lawton DRY, et al. Influence of obesity and intra-operative imaging guidance technology on acetabular cup positioning in total hip arthroplasty. Arch Orthop Trauma Surg. 2023;143(11):6857–63. doi: 10.1007/s00402-023-04922-xEftekhary N, Shimmin A, Lazennec JY, et al. A systematic approach to the hip-spine relationship and its applications to total hip arthroplasty. Bone Joint J. 2019;101-B(7):808–16. doi: 10.1302/0301-620X.101B7.BJJ-2018-1188.R1Christensen TH, Egol A, Pope C, et al. How Does Surgical Approach Affect Characteristics of Dislocation After Primary Total Hip Arthroplasty? J Arthroplasty. 2023;38(7 Suppl 2):S300–S5. doi: 10.1016/j.arth.2023.05.034Ramadanov N, Ostojic M, Lazaru P, et al. Risk Factors and Predictors for Functional Outcome and Complication Rate in Total Hip Arthroplasty through Minimally Invasive and Conventional Approaches: A Systematic Review and Meta-Regression Analysis of 41 Randomized Controlled Trials. Journal of Clinical Medicine. 2023;12(18):5895. doi: 10.3390/jcm12185895Callanan MC, Jarrett B, Bragdon CR, et al. The John Charnley Award: risk factors for cup malpositioning: quality improvement through a joint registry at a tertiary hospital. Clin Orthop Relat Res. 2011;469(2):319–29. doi: 10.1007/s11999-010-1487-1Khalifa AA, Abdelnasser MK, Ahmed AM, Shetty GM, Abdelaal AM. Smartphone Application Helps Improve the Accuracy of Cup Placement by Young, Less-Experienced Surgeons during Primary Total Hip Arthroplasty. Arch Bone Jt Surg. 2022;10(3):278–85. doi: 10.22038/ABJS.2021.52402.2587Khalifa AA, Adam MF, Mahran MA. Adjustment of Acetabular Cup Inclination Assisted by Smartphone during Revision Total Hip Arthroplasty: Surgical Technique and Report of Four Cases. Rev Bras Ortop (Sao Paulo). 2025;60(1):1–7. doi: 10.1055/s-0045-1804490Hill JC, Gibson DP, Pagoti R, Beverland DE. Photographic measurement of the inclination of the acetabular component in total hip replacement using the posterior approach. J Bone Joint Surg Br. 2010;92(9):1209–14. doi: 10.1302/0301-620X.92B9.24476Khalifa AA, Bakr HM, Said E, Mahran MA. Technical Note on Using Intraoperative Smartphone Applications to Adjust Cup Inclination Angle during Total Hip Arthroplasty (THA). Arch Bone Jt Surg. 2020;8(6):734–8. doi: 10.22038/abjs.2020.44466.2217Meermans G, Goetheer-Smits I, Lim RF, Van Doorn WJ, Kats J. The difference between the radiographic and the operative angle of inclination of the acetabular component in total hip arthroplasty: use of a digital protractor and the circumference of the hip to improve orientation. Bone Joint J. 2015;97-B(5):603–10. doi: 10.1302/0301-620X.97B5.34781Vendittoli PA, Ganapathi M, Duval N, et al. Randomised controlled trial comparing two methods of acetabular cup positioning during total hip arthroplasty. Hip Int. 2007;17(3):137–42. doi: 10.1177/112070000701700303O’Neill CKJ, Hill JC, Patterson CC, et al. Reducing variability in apparent operative inclination during total hip arthroplasty: findings of a randomised controlled trial. Hip Int. 2018;28(3):234–9. doi: 10.1177/1120700018777485