Smartphone-assisted technique in total hip arthroplasty can improve the precision of acetabular cup placement: a randomised controlled trial

Abstract

Background: Malposition of the acetabular component mainly results from intraoperative pelvic motion and manual errors during cup placement. We investigated the outcomes of a device that uses a level indicator application of a smartphone to function as a pelvic tilt goniometer to assess intraoperative motion. The cup positions outside Lewinnek’s safe zone were compared between the smartphone-assisted technique and the conventional method that uses a mechanical alignment guide. Methods: A randomised controlled trial was conducted among 64 patients receiving primary cementless total hip arthroplasties (THAs) via a posterolateral approach from June 2015 to February 2017. Acetabular components were implanted either by conventional technique ( n = 32) or using smartphone technique ( n = 32). Inclination and anteversion angles were measured in supine pelvic radiographs. Results: The inclination angle in the smartphone group was not significantly different from the conventional group (41.2° ± 3.9° vs. 40.3° ± 7.9°, p = 0.567). The anteversion angle was also similar (19.3 ± 3.8° vs 19.1° ± 5.9°, p = 0.856). However, the standard deviation of the angle in the smartphone group was significantly lower for inclination ( p < 0.001) and anteversion ( p = 0.016). There were 3 outliers (9.4%) in the smartphone group, but 13 (40.6%) in the conventional group ( p = 0.008). The risk ratio was 0.23 (95% CI, 0.07–0.73). The risk difference was −0.31 (95% CI, –0.51– –0.11). Conclusion: The smartphone-assisted technique in THA improves the precision of cup placement and decreases the percentage of safe zone outliers. Thai Clinical Trials Registry (ID: TCTR20151123002).

The Accuracy of Patient-Specific Instrumentation with Laser Guidance in a Dynamic Total Hip Arthroplasty: A Radiological Evaluation

“…Dynamic planning has to be accurately reproduced in the operating room to finalize the functional advantages. The malposition of components mainly results from the errors in patient positioning, intraoperative pelvic motion and manual errors during the surgery [ 43 ]. Traditional free hand techniques successfully achieve target ranges for both inclination and anteversion in only 47% of cases with other studies reporting even lower rates [ 20 , 21 , 44 ].…”

“…It has been reported that 80% to 96% of components were placed in the safe zone using computer navigation while 100% were placed using robotics. In our series, all of the postoperative acetabular components were within Lewinnek’s safe zone [ 43 ].…”

Patient-Specific Instrumentation with Laser-Guide-Navigated THA: Clinical and CT Evaluation of the First 100 Cases

“…The literature regarding acetabular cup placement is quite extensive, while there are limited data on the femoral stem position [15,19,22]. The recent literature agrees regarding the relevance of femoral osteotomy planning for a successful THA; the femoral cut mainly affects the leg length, the hip offset, and the tracking of the implant [21,36].…”