Measured vs Navigated Techniques in Total Hip Arthroplasty

Accurate reconstruction of the native hip parameters following total hip arthroplasty is associated with improved outcome. In order to improve ability for optimum reconstruction, 3-D templating software can be utilized that provide detailed information regarding native anatomy. In order to achieve reconstruction within acceptable parameters as per pre-operative plan, some surgeons propose the use of intra-operative devices that measure component orientation and joint reconstruction ("Measured-THA"), whilst others propose the use of navigation tools ("Navigation-THA). Both techniques have shown superiority compared to the most commonly used "freehand" technique, but no prior study has assessed for superiority between these 2 techniques. Furthermore, to-date assessment of post-operative reconstruction has not been tested in detail as post-THA assessments are based on radiographs which provide incomplete, 2-dimensional, assessments and are lacking the important axial plane reconstruction parameters. The aims of this prospective, randomized, trial are to 1. appraise the ability to achieve the pre-operative 3-D plan (as per FormusLab) through a comparison of pre-op plan to post-operative reconstruction; 2. compare ability to accurately reconstruct hip following THA between "navigated-" (IntelliJoint®) and "measured-" techniques; and in doing so it will also 3. assess the accuracy of the intra-operative assessments of reconstruction through a comparison of objective (i.e. measured) intra-operative assessments with the post-operative reconstructions achieved.

Inclusion Criteria: * Patients who are signed for a THA for primary or secondary osteoarthritis without overt deformity that would require revision type implants and with good enough bone quality to be listed for uncemented component implantation. Exclusion Criteria: * Secondary OA due to Dysplasia (Hartofilakidis \>1) * Avascular necrosis of the hip with destruction of joint structure * Sequelae of Pediatric deformity with abnormal anatomy * Cemented fixation of femur or acetabulum * Previous arthroplasty-type procedure * Previous septic arthritis of the hip