Ahmed Khalifa - Orthopaedic Department, Qena Faculty of Medicine and University Hospital, South Valley University, Qena, Egypt
Mohammad Abdelnasser - Orthopaedic and Traumatology Department, Assiut University Hospital, Assiut, Egypt
Ahmed M. Ahmed - Orthopaedic Department, Qena Faculty of Medicine and University Hospital, South Valley University, Qena, Egypt
Gautum Shetty - Knee & Orthopaedic Clinic, Powai, Mumbai Head of Research, AIMD Research
Ahmed Abdelaal - Orthopaedic and Traumatology Department, Assiut University Hospital, Assiut, Egypt

Background: Dislocation after total hip arthroplasty (THA) partly under the surgeon’s control, by appropriate placement of the components. We aimed in this study to determine the accuracy of using intra-operative smartphone applications (Apps) to place the acetabular cup within the safe abduction angle by less experienced surgeons during THA surgery when compared to the conventional freehand technique for cup placement.Methods: Sixty primary THAs were performed, ۳۰ using the conventional freehand technique (control group) and ۳۰ using the smartphone app technique (study group) to determine the acetabular cup abduction angle by the same young surgeon with less than one year of experience. Postoperative mean cup abduction angle, mean cup anteversion angle, and the percentage of cups within the safe abduction zone as measured on radiographs were compared between the two groups.Results: In the study group, the mean cup abduction angle was significantly lower (P=۰.۰۰۰۸), and the acetabular cup was placed within the safe zone in a significantly higher (P<۰.۰۰۱) percentage of patients (۹۳% vs ۶۳%) when compared to the control group. However, there was no significant difference (P=۰.۴۰) between the two groups when the mean cup anteversion angle was compared.Conclusion: The smartphone app technique may help achieve an accurate acetabular cup abduction angle and a higher percentage of cups placed within the safe zone of abduction by a less experienced surgeon when compared to the conventional freehand technique. Using tools such as the smartphone app to measure the acetabular cup positioncan reduce intraoperative errors by young and less experienced surgeons during THA surgery.Level of evidence: IV

acetabular cup, Lewinnek safe zone, Total hip arthroplasty, total hip replacement, Smartphone