A Novel Measurement Using Digital Radiography to Minimize Fluoroscopy in Total Hip Arthroplasty

Preoperative templating for total hip arthroplasty (THA) is fraught with uncertainty. Specifically, the conventional measurement of the lesser trochanter to the center (LTC) of the femoral head used in preoperative planning is easily measured on a template but not measurable intraoperatively. The purpose of this study was to examine the utility of a novel measurement that is reproducible both on templating and in surgery as a more accurate and practical guide. We retrospectively reviewed 201 patients with a history of osteoarthritis who underwent primary THA. For preoperative templating, the distance from the top of the lesser trochanter to the equator (LeTE) of the femoral head was measured on a calibrated digital radiograph with a neutral pelvis. This measurement was used intraoperatively to guide the choice of the trial neck and head. As with any templating technique, the goal was to construct a stable, impingement-free THA with equivalent leg lengths and hip offset. In evaluating this novel templating technique, the primary outcomes measured were the number of trial reductions and the amount of fluoroscopic time, exposures, and radiation required to obtain a balanced THA reconstruction. Using the LeTE measurement, the mean number of trial reductions was 1.21, the mean number of intraoperative fluoroscopy images taken was 2.63, the mean dose of radiation exposure from fluoroscopy was 0.02 mGy, and the mean fluoroscopy time per procedure was 0.6 seconds. In hips templated with the conventional LTC prior to the LeTE, the mean fluoroscopy time was 0.9 seconds. There was a statistically significant difference in fluoroscopy time (p < 0.001). The LeTE is a reproducible measurement that transfers reliably from digital templating to surgery. This novel preoperative templating metric reduces the fluoroscopy time and consequent radiation exposure to the surgical team and may minimize the number of trial reductions.

The Accuracy and Ability of Preoperative Templating to Restore Femoral Offset in Calcar-Guided Short-Stem Total Hip Prosthesis through Direct Anterior Approach

The aim of this study was to assess the applicability and ability of preoperative templating to restore femoral offset and hip length with a calcar-guided short-stem implant design in total hip arthroplasty through the direct anterior approach. Preoperative measurements were performed of femoral offset, hip length, and stem size and compared with the perioperative placed prosthesis in 100 patients undergoing primary total hip replacement through direct anterior approach. Additionally, the pre- and postoperative femoral offset and hip length were compared to evaluate the ability to restore the offset and hip length with this kind of femoral short stem. With an acceptance of 1 size difference pre- and postoperatively, a 94% accuracy of predicting the size of the calcar-guided short stem was achieved with templating. Femoral offset was within means of 5 mm in 82.2% of the patients. Postoperative hip length was within 6 mm in 90% of the patients compared with the preoperative length.The use of preoperative templating for total hip arthroplasty with calcar-guided short-stem implants was proven to be a useful tool to predict the definite implanted size of the femoral prosthesis. Our results show that this new stem design does not significantly differ from previous reported outcomes with other stem designs and is competent to restore the femoral offset and hip length within clinical acceptable range. Level of evidence Level 3 retrospective case study.

480 Preoperative Templating in Hip Hemiarthroplasty Improves Femoral Offset and Function

The use of preoperative templating for hip hemiarthroplasty increases the likelihood of successfully restoring offset. This study sought to identify whether templating improves radiographic and clinical outcomes in this group. Data belonging to all patients that underwent hip hemiarthroplasty between March 2018 and March 2019 were collected. The patients were grouped based on whether or not their preoperative images were templated. Radiographs were studied retrospectively to calculate preoperative and postoperative offset and LLD for each patient. The clinical outcomes that were measured included the rate of periprosthetic fracture, dislocation and contra-lateral neck of femur fracture for each group. Data was analysed by SPSS. There were 208 patients of which 72 were templated and 136 not templated. The percentage difference between the preoperative and postoperative offset was lower in the templated group (p &lt; 0.05). There was no significant difference in radiographic LLD between the two groups. There was no significant difference in the clinical outcomes between the two groups. A significantly closer restoration to the original offset was achieved with preoperative templating, which is likely to improve function in this group. There were no significant differences in the other clinical outcomes between the two groups.

The Rate of Correctly Planned Size of Digital Templating in Two Planes—A Comparative Study of a Short-Stem Total Hip Implant with Primary Metaphyseal Fixation and a Conventional Stem

(1) Background: Preoperative templating is mainly conducted on an anteroposterior pelvic overview X-ray. For short stem hip arthroplasty, the choice of the optimal size is especially crucial to avoid complications. Thus, the study aimed to determine if there is an increased rate of correctly planned sizes using two radiological planes. (2) Methods: 50 patients with a conventional stem and 100 with a short stem total hip arthroplasty were analyzed. Without knowing the implanted size, three independent orthopedic surgeons performed digital templating: once using the anteroposterior pelvic overview only and once using the lateral view in addition. (3) Results: The rate of correctly planned sizes (+/−1 size compared to the inserted size) of templating with one plane was 86.3% ± 9.5% in short stem hip arthroplasty and 88.4% ± 6.0% in conventional stem arthroplasty. By adding the lateral view, the rate of correctly planned sizes was 89.9% ± 12.0% for the short stem hip arthroplasty group and 89.4% ± 9.8% for the conventional group (p > 0.1). (4) A potential positive effect of preoperative templating using an additional lateral X-ray view for short stem implants may be suggested based on the results of this study, which did, however, not reach statistical significance.

Is the contralateral lesser trochanter a reliable reference for planning of total hip arthroplasty – a 3-dimensional analysis

Background Preoperative templating in total hip arthroplasty (THA) is mandatory to achieve appropriate offset and leg length equality. However, templating methods using the contralateral hip might be susceptible to errors resulting from side-differences in the femoral morphology. The distance of the lesser trochanter to the femoral head center (LTFHD) is a frequently used reference parameter for preoperative planning and intraoperative validation during THA. However, currently no three-dimensional (3D) analysis of side differences of the LTFHD exists. Methods Using Computer tomography (CT)-based surface models from 100 paired femora (50 cadavers), side-to-side asymmetry of the LTFHD, femoral length, femoral head diameter (FHD) and femoral antetorsion were analyzed. Univariate linear regression models were established to evaluate potential associations between sides regarding LTFHD and FHD as well as a correlation of these parameters with each other. Results Statistically significant side-differences were found for the LTFHD (p = 0.02) and FHD (p = 0.03) with a mean absolute side-difference of 1.6 ± 1.4mm (range 0.1–5.5mm) and 0.4mm ± 0.6mm (range 0–3mm), respectively. The ratio between the LTFHD and FHD was consistent with an average value of 1.16 ± 0.08 and reliable between sides with a correlation coefficient (r) of 0.72 (p < 0.01). Conclusions The LTFHD is a reliable reference parameter for preoperative templating and intraoperative validation during THA with a high correlation between sides (r = 0.93, p < 0.01). However, 8 % of the investigated specimens revealed a LTFHD of more than 4mm, which should be anticipated during THA to avoid unsatisfiable results.