A laser guide technique: a novel method for accurate acetabular cup alignment in total hip arthroplasty

For accurate cup alignment without navigation in total hip arthroplasty (THA), we developed a "laser guide technique." The major purposes of this paper are to introduce the technique and compare its accuracy with a conventional manual technique. As a clinical outcome, the dislocation rate was reviewed. Our laser guide technique, which includes preoperative postural adjustment and intraoperative angular reference, has been detailed in the manuscript. 599 hips in 523 patients who underwent primary THA with piriformis-sparing posterolateral approach in April 2010-March 2016 were reviewed. Patients were divided into three groups: conventional group (135 hips), laser guide group (80 hips), and laser + radiographic alignment guide group (384 hips). Radiographic inclination (RI) and radiographic anteversion (RA) errors were evaluated. The dislocation rate was reviewed in 540 hips in 476 patients who were followed up > 2 years postoperatively. Absolute values of the RI/RA error in the three groups were 5.3 degrees +/- 4.0 degrees/6.5 degrees +/- 4.5 degrees, 4.0 degrees +/- 2.8 degrees/4.9 degrees +/- 4.4 degrees, and 3.3 degrees +/- 2.6 degrees/3.6 degrees +/- 2.8 degrees, respectively, indicating substantially enhanced accuracy with laser and radiographic alignment guide. The dislocation rates were 2.5% (3/119) and 0.2% (1/421) in the conventional and laser groups, respectively. Our novel laser guide technique considerably enhanced cup alignment accuracy, suggesting its potential applicability for THA in the lateral decubitus position.