Excessive standing posterior pelvic tilt (PT), lumbar spine stiffness, low pelvic Incidence (PI), and severe sagittal spinal deformity (SSD) have been linked to increased dislocation rates. We aimed to compare the prevalence of these 4 parameters in unstable and stable primary Total Hip Arthroplasty (THA) patients. In this retrospective cohort study, 40 patients with instability following primary THA for osteoarthritis were referred for functional analysis. All patients received lateral X-rays in standing and flexed seated positions to assess functional pelvic tilt and lumbar lordosis (LL). Computed tomography scans were used to measure pelvic incidence and acetabular cup orientation. Literature thresholds for “at risk” spinopelvic parameters were standing pelvic tilt ≤ −10°, lumbar flexion (LLstand – LLseated) ≤ 20°, PI ≤ 41°, and sagittal spinal deformity (PI – LLstand mismatch) ≥ 10°. The prevalence of each risk factor in the dislocation cohort was calculated and compared to a previously published cohort of 4042 stable THA patients.Introduction
Methods
In total hip arthroplasty, correct sizing is critical for fixation and longevity of cementless components. Previously, three-dimensional CT templating has been shown to be more accurate than using 2D radiographs. The accuracy of the Optimized Positioning System (OPSTM) planning software has not been reported. The aim of this study was to measure the accuracy of the OPS planning software in predicting the implanted acetabular cup and femoral stem size when used with the direct anterior approach. Between October 2018 and March 2019, 95 patients received a bone preserving cementless MiniHip stem (Corin, UK). Sixty-three of these patients also received a cementless Trinity cup (Corin, UK). All patients were sent for OPSTM pre-operative planning, a patient-specific dynamic modelling software used to determine the optimal acetabular and femoral component size and positions. Average age was 57 (28 to 78) and 44% were female. All cases were performed using the direct anterior approach. The sizes of implants used were retrospectively compared to the planned OPSTM sizes.Introduction
Method
