Planning For Total Hip Arthroplasty Research Articles

Determination of the hip rotation centre from landmarks in pelvic radiograph

ObjectiveThe hip rotation centre (HRC) is an important reference point in cases of total hip arthroplasty (THA). The aim of this study is to investigate the reference points in the Turkish population that enable the identification of the HRC in standard pelvic radiographs. MethodsThe pelvic radiographs of 50 women and 50 men were examined. The mean age was 46.2 (range; 18–91). Patients with deformity of the hip joint and non-standard pelvic radiograph due to hip flexion contracture were excluded from the study. The pelvic height (PH), the distance between the HRC and teardrop (HRC-Td), and the HRC and the line tangent tuber ischiadicums (HRC-TI) were measured. The ratio of HRC-Td and HRC-TI to PH were calculated. The first is called “the horizontal-HRC ratio” and the second, “the vertical-HRC ratio”. ResultsMean PH was 239 (±13.58) mm in males and 225 (±12.52) in females (p < 0.0001). The distances of HRC-TI were 71 (±6.35) and 65 (±6.72) mm (p < 0.0001) and the distance of HRC-Td were 34 (±3.73) and 30 (±4.05) mm (p = 0.0007), respectively. The vertical-HRC ratios were 30.01% (±2.05) for males, 29.10% (±2.35) for females, the horizontal-HRC ratio, 14.25% (±1.42) and 13.69% (±1.38), respectively (p > 0.05). ConclusionAlthough the quantitative values obtained in the present study differ between the genders, the ratios (“vertical-HRC” and “horizontal-HRC”) are comparable in both sexes. The results show that these proposed ratios can be used in THA planning, regardless of gender in the Turkish population Level of evidenceLevel IV, diagnostic study.

Lesser Trochanter Size on Plain Anteroposterior Radiographs Correlates With Native Femoral Anteversion

BackgroundAssessing femoral version in orthopedic surgery is important for preoperative planning of total hip arthroplasty, especially for recognizing excessive anteversion or retroversion. The present study addressed the following: (1) Is the position of the lesser trochanter correlated to the femoral neck axis? (2) If so, may femoral version be assessed by means of plain pelvic radiographs? MethodsThree-dimensional computed tomography scans of 60 patients undergoing minimally invasive cement-free total hip arthroplasty were retrospectively analyzed, particularly with regard to the relation between the femoral neck axis and the lesser trochanter, the femoral version, and the size of the projected lesser trochanter in different rotational positions. Based on linear regression, a biomathematical formula was developed to assess femoral anteversion on plain radiographs depending on the visible part of the lesser trochanter. ResultsThe mean difference between the location of the lesser trochanter axis and the femoral neck axis was 43.3° ± 6.2°. Eighty-seven percent of patients (52 of 60) had a deviation of <10° from the mean value of 43.3°. By virtual rotation of the femur in steps of 10°, the visible part of the lesser trochanter linearly increased with anteversion of the femur: femoral version = (lesser trochanter size − 5.57) × 4.17. There was a high correlation between the visible part of the lesser trochanter and femoral version (R2 = 0.75; P < .001). The lesser trochanter was no longer visible with femoral retroversion in each of the 60 data sets. ConclusionThe projected size of the lesser trochanter as available on plain pelvic AP radiographs correlates with native femoral anteversion.

The influence of surgical approach on postoperative pelvic tilt after total hip arthroplasty.

Past reports have shown the tendency of posterior pelvic tilt to increase over time after total hip arthroplasty (THA). We have hypothesized that the volume and extent of released joint capsule may influence the change in postoperative pelvic tilt. This study was conducted to ascertain whether surgical approach during THA (posterior or anterior) has an effect on postoperative changes in pelvic tilt. We conducted a retrospective review of 81 hips in 60 patients. Patients classified as Crowe group 2, 3, and 4, those who had multiple previous compression fractures, and those with spinal fusion due to spinal arthrosis were excluded. Also, those who had previously undergone THA or total hip resurfacing also were excluded. Patients were divided into two groups, those with preoperative anterior pelvic tilt and those with posterior tilt. Preoperative and postoperative X-rays and CT scans for each group were assessed to determine the chronological change in pelvic tilt, and the data were statistically analyzed for patients who had experienced both the posterior and anterior approaches. Regardless of surgical approach, there was no significant difference in the mean change in postoperative APP angle over time in either the bilateral or unilateral cases or in the groups of preoperative anterior or posterior pelvic tilt. Our results showed that surgical approach does not influence postoperative pelvic tilt after THA. In preoperative planning for THA, therefore, surgeons may need not to consider the difference of surgical approach with regard to postoperative changes in pelvic tilt.

Accuracy and reproducibility of preoperative three-dimensional planning for total hip arthroplasty using biplanar low-dose radiographs : A pilot study

BackgroundIn total hip arthroplasty (THA), the acetabular cup and femoral stem must be correctly sized and positioned to avoid intraoperative and postoperative complications, achieve good functional outcomes and ensure long-term survival. Current two-dimensional (2D) techniques do not provide sufficient accuracy, while low-dose biplanar X-rays (EOS) had not been assessed in this indication. Therefore, we performed a case-control study to : (1) evaluate the prediction of stem and cup size for a new 3D planning technique (stereoradiographic imaging plus 3D modeling) in comparison to 2D templating on film radiographs and (2) evaluate the accuracy and reproducibility of this 3D technique for preoperative THA planning. HypothesisAccuracy and reproducibility are better with the 3D vs. 2D method. Patients and methodsStem and cup sizes were retrospectively determined by two senior surgeons, twice, for a total of 31 unilateral primary THA patients in this pilot study, using 3D preplanning software on low-dose biplanar X-rays and with 2D templating on conventional anteroposterior (AP) film radiographs. Patients with a modular neck or dual-mobility prosthesis were excluded. All patients but one had primary osteoarthritis; one following trauma did not have a cup implanted. The retrospectively planned sizes were compared to the sizes selected during surgery, and intraclass coefficients (ICC) calculated. Results3D planning predicted stem size more accurately than 2D templating: stem sizes were planned within one size in 26/31 (84%) of cases in 3D versus 21/31 (68%) in 2D (P=0.04). 3D and 2D planning accuracies were not significantly different for cup size: cup sizes were planned within one size in 28/30 (92%) of cases in 3D versus 26/30 (87%) in 2D (P=0.30). ICC for stem size were 0.88 vs. 0.91 for 3D and 2D, respectively. Inter-operator ICCs for cup size were 0.84 vs. 0.71, respectively. Repetitions of the 3D planning were within one size (except one stem), with the majority predicting the same size. DiscussionIncreased accuracy in 3D may be due to the use of actual size (non-magnified) images, and judging fit on AP and lateral images simultaneously. Results for other implant components may differ from those presented. Size selection may improve further with planning experience, based on a feedback loop between planning and surgical execution. Level of evidenceLevel III. Retrospective case-control study.

The Accuracy of Digital Templating for Primary Total Hip Arthroplasty: Is There a Difference Between Direct Anterior and Posterior Approaches?

BackgroundThe direct anterior approach (DAA) has gained recent popularity for total hip arthroplasty (THA), as it provides immediate feedback on cup position and limb length using fluoroscopy. The purpose of this study is to evaluate any differences in the accuracy of digital templating for preoperative planning of THA, performed with 2 different surgical approaches: DAA using a radiolucent table with intraoperative fluoroscopy and the posterior approach (PA). MethodsOne hundred thirty-one consecutive patients (148 hips) underwent a THA by a single surgeon, using the same cup and stem designs. Seventy-five hips were performed using the DAA using a fracture table and fluoroscopy. Seventy-three hips were performed using the PA with the patient positioned in lateral decubitus using standard positioners without fluoroscopy. Preoperative radiographs were digitally templated by the same surgeon. ResultsThe PA patients had a higher mean body mass index and were more likely to have a preoperative diagnosis of avascular necrosis. The accuracy of templating for predicting the cup size to be within 2 mm was 91% for DAA vs 88% for PA (P = .61). For stem size, the accuracy was 85% (to within 1 size) for the DAA vs 77% for the PA (P = .71). Likewise, there was no significant difference in predicting the final stem's neck angle or femoral offset. ConclusionDigital templating was found to be a reliable and highly accurate method for predicting component sizes and offset for THA, regardless of using either the PA or the DAA with fluoroscopy.

Posterior lesser trochanter line should not be used as reference for assessing femoral version in CT scans: a retrospective reliability and agreement study.

Background The estimation of femoral version in preoperative planning of total hip arthroplasty and to assess complications after total hip arthroplasty is crucial. Recent studies have recommended the posterior lesser trochanter line as an intraoperative reference for estimating femoral version. We hypothesized, that if there is a correlation, the posterior lesser trochanter line could be used to assess femoral version in computed tomography (CT) scans. Purpose To evaluate the correlation between the posterior lesser trochanter line and the posterior femoral condyle axis. Material and Methods CT scans of 126 patients after unilateral total hip arthroplasty were analyzed by means of a newly developed digital planning software for CT scans. Both hips were measured, the angle between the posterior lesser trochanter line and the posterior femoral condyle axis was determined, and the relationship between both lines was evaluated. Results We found significant differences between male and female patients ( P < 0.001) and between left and right femora ( P = 0.001). There was no significant difference between healthy hips and hips with osteoarthritis after total hip arthroplasty ( P = 0.901). Conclusion There is no reliable correlation between posterior lesser trochanter line and posterior femoral condyle axis. Therefore, posterior lesser trochanter line should not be used to assess femoral version in CT scans. As a consequence, the gold standard for measuring femoral version should still be a three-dimensional CT scan of the whole femur.

Preoperative planning of total hip arthroplasty on dysplastic acetabuli.

When performing total hip arthroplasty (THA) on a dysplastic hip, proper positioning of the acetabular component may not allow for more than 70% coverage. Structural support in the form of an autograft or a high porosity metal augment may be necessary. The purpose of the study was to investigate the value of preoperative templating and deformity classification in predicting cup coverage and the need for structural support. 65 cases of THA for DDH were retrospectively analysed. 2 observers independently classified each dysplastic hip according to Hartofilakidis and determined the extent of cup coverage via templating software on preoperative digital AP pelvic radiographs. Weighted kappa interobserver agreement was 0.68 for cup coverage and 0.76 for Hartofilakidis type. Structural support was necessary in 10 hips. No structural support was necessary in Hartofilakidis type 1, dysplasia cases. However, 27-30% of cases with type 2 or type 3 dysplasia required structural support. All cases with templated cup coverage of 65% or less required structural support. Templated coverage within 65-75% and over 75% resulted in 20% and 10% of patients receiving structural augmentation, respectively. Preoperative planning for THA in the setting of hip dysplasia is crucial and can provide valuable insight to the need for column augmentation. However, the 3-D severity of the deformity may be underestimated in the 2-D radiographs.

Preoperative planning of hip joint arthroplasty in terminal stage degenerative diseases in adolescents

The modern aspects of diagnosis, preoperative planning, and indications for total hip arthroplasty in adolescents are reviewed in the article. The aim of the article is the systematization of the tactics of preoperative planning of total hip arthroplasty in the terminal stage degenerative diseases in adolescents. Preoperative planning is very challenging in total hip arthroplasty in adolescents because in all cases on hip radiographs severe anatomical hypoplasia or destruction of both the pelvic and femoral components is visualized. Before the surgery, patients undergo a complex multifactorial examination: orthopedic status specification, X-ray and radio-functional diagnostics, computed tomography and magnetic resonance imaging. Examination results allow us to determine the anatomy of the acetabulum, the path of the femoral head within it, the defect type and the diameter of brim of the acetabulum area, its depth, the integrity of the walls and roof. The authors performed total hip arthroplasty in 32 patients aged 15-18 years (11 boys and 21 girls) with terminal stages degenerative-dystrophic diseases of the hip joint with the implementation of preoperative planning in accordance with described methods. Comparison of preoperative planning results with the clinical results of total hip arthroplasty in most cases showed the agreement of calculations with the intraoperative analysis data. After total arthroplasty, evaluation of patients’ hip joint function was from 92 to 100 points. Preoperative planning is one of the most important stages of total hip arthroplasty in adolescent orthopedics. It allows to obtain reliable information about the needed model of the endoprosthesis, the optimal size of its components, the depth of the acetabulum reaming, the level of the femoral neck resection, placement and orientation of the implant cup and the stem, the possibility of correction of the lower limbs length and to achieve good results in the treatment of patients with severe congenital or acquired hip defects and progressive thigh non-weight bearing.

Digital templating for THA: a simple computer-assisted application for complex hip arthritis cases.

Total hip arthroplasty (THA) is the standard procedure for end-stage arthritis of the hip. Its technical success relies on preoperative planning of the surgical procedure and virtual setup of the operative performance. Digital hip templating is one methodology of preoperative planning for THA which requires a digital preoperative radiograph and a computer with special software. This is a prospective study involving 23 patients (25 hips) who were candidates for complex THA surgery (unilateral or bilateral). Digital templating is done by radiographic assessment using radiographic magnification correction, leg length discrepancy and correction measurements, acetabular component and femoral component templating as well as neck resection measurement. The overall accuracy for templating the stem implant's exact size is 81%. This percentage increased to 94% when considering sizing within 1 size. Digital templating has proven effective, reliable and essential technique for preoperative planning and accurate prediction of THA sizing and alignment.

Nuances of preoperative planning of total hip arthroplasty in patients with hip dysplasia

Purpose of the study - to evaluate in different groups of patients variability of anatomical changes that may affect the difference in the length of the lower extremities and affect on the results of the preoperative planning. Material and methods. As study material we used long film X-ays of 142 patients. A main group comprised 69 patients with varying severity of hip dysplasia. Control group consisted of 73 patients without hip pathology. All patients were performed long film X-rays, and measurements of relative and absolute lengths of the lower limbs, followed by analysis of the data. Results. Analysis of the measurements showed that none of the patients had absolutely equal length of the lower limbs, even in the control group in 56.2% of the observations noted the absolute difference of the lower extremities length more than 5 mm, and in 9.6% of patients - from 20 to 35 mm. In assessing the difference of the lower extremities length on AP pelvic view in the main group only one patient of 69 had the same length of the legs, and in 61 cases the difference was more than 5 mm, that it was clinically significant. Of practical interest is the fact that in the main group shortening of the operated limb was observed in 51 of 69 patients in AP views of the pelvis, but the results of measurements of the anatomical length of limbs long film X-rays compared with measurements of the relative shortening on the pelvis AP views showed that clinically significant difference exceeding 5 mm between measurements observed in 68.1% of cases. The greatest difference between the measurements of the limbs length on the pelvis AP views and long film X-rays observed in patients with unilateral hip dislocation and averaged 17.0 mm. Conclusion. Performing preoperative planning in patients with dysplasia only on pelvis AP views not allow properly compensate the difference of the lower extremities lengths, which may adversely affect the functional results of surgery and as a result, the patient’s satisfaction. Therefore, planning THA, especially at high hip dislocation, it is necessary to calculate the difference of the lower extremities lengths considering as the difference of the lengths on AP pelvis views and long film X-rays.

Low Dose Computed Tomography for 3D Planning of Total Hip Arthroplasty: Evaluation of Radiation Exposure and Image Quality.

The aim of the study was to compare radiation exposure and image quality between dedicated computed tomography (CT) protocols for preoperative total hip arthroplasty (THA) planning. Three protocols with automated tube current modulation using 64-slice (n = 177) and 128-slice CT scanners without (n = 129) and with automated tube voltage preselection (n = 84) were compared. All 390 CTs were of sufficient quality for THA planning. Mean DLP was 235.0 mGy*cm (effective dose 2.8 mSv). Lowest radiation exposure (2.5 mSv) was seen with automated voltage preselection and the algorithm's selection was 100 kV (90.5% of patients) and 120 kV. Lowest image noise was seen in the highest dose group (3.1 mSv, 128-slice CT fixed tube voltage). A significant difference in cortical bone radiodensity was seen between 100 kV and 120 kV (P < 0.0001). Preoperative pelvic CT for THA planning is possible with very low radiation dose and reliable quality. Automated voltage preselection further decreases the effective dose by 18.2%.

The T-line as an intraoperative landmark for reproducing the native femoral anteversion during hip arthroplasty

Three-dimensional computed tomographic (CT)-based preoperative planning for total hip arthroplasty (THA) enabled us to evaluate the cut surface of the femoral neck osteotomy. When we planned the stem placement in 20° of anteversion, we noticed that the line connecting the trochanteric fossa and the middle of the medial cortex of the femoral neck (T line) was coincident with the component torsion in many cases. We attempted to evaluate the accuracy of the T line for reproducing the native femoral anteversion during THA comparing it with the midcortical line, the reference guide previously reported by Suh. The institutional review board allowed a retrospective review of CT images of 100 normal hip joints. We performed virtual THA using the non-anatomic straight stem at three different cutting heights of 5, 10, or 15 mm above the lesser trochanter. The anteversion of the stem implanted parallel to the T line or midcortical line was measured. The mean difference of the stem anteversion using the T line and the native femoral anteversion was -0.77º (95 % CI: -1.92º to 0.38º), 0.69º (95 % CI: -0.42º to 1.79º) and 3.38º (95 % CI: 2.29º-4.46º) at cutting heights of 5, 10 and 15 mm, respectively. Using the midcortical line, stems tended to retroversion. Aligning the stem parallel to the T line on the cut surface provides a good reproduction of the femoral anteversion. The T line can be an useful intraoperative reference guide for the anteversion of the femoral component in THA for patients without severe hip deformity.

Computed tomography for preoperative planning in total hip arthroplasty: what radiologists need to know

The number of total hip arthroplasties is continuously rising. Although less invasive surgical techniques, sophisticated component design, and intraoperative navigation techniques have been introduced, the rate of peri- and postoperative complications, including dislocations, fractures, nerve palsies, and infections, is still a major clinical problem. Better patient outcome, faster recovery and rehabilitation, and shorter operation times therefore remain to be accomplished. A promising strategy is to use minimally invasive techniques in conjunction with modular implants, aimed at independently reconstructing femoral offset and leg length on the basis of highly accurate preoperative planning. Plain radiographs have clear limitations for the correct estimation of hip joint geometry and bone quality. Three-dimensional assessment based on computed tomography (CT) allows optimizing the choice and positions of implants and anticipating difficulties to be encountered during surgery. Postoperative CT is used to monitor operative translation and plays a role in arthroplastic quality management. Radiologists should be familiar with the needs of orthopedic surgeons in terms of CT acquisition, post-processing, and data transfer. The CT protocol should be optimized to enhance image quality and reduce radiation exposure. When dedicated orthopedic CT protocols and state-of-the-art scanner hardware are used, radiation exposure can be decreased to a level just marginally higher than that of conventional preoperative radiography. Surgeons and radiologists should use similar terminology to avoid misunderstanding and inaccuracies in the transfer of preoperative planning.

Financial implication for being the national centre for the treatment and management of pelvic and acetabular fractures in Ireland: The need for a new budget strategy?

Financial implication for being the national centre for the treatment and management of pelvic and acetabular fractures in Ireland: The need for a new budget strategy?

(i) Informed consent and pre-operative planning for total hip arthroplasty

Abstract This article reviews informed consent in general and with particular reference to total hip arthroplasty, including the legal and ethical issues. It then reviews the remainder of the pre-operative planning process for joint replacement to show that this is a continuous process rather than a series of separate events.

Prediction of three-dimensional femoral offset from AP pelvis radiographs in primary hip osteoarthritis

BackgroundIn pre-operative planning for total hip arthroplasty (THA), femoral offset (FO) is frequently underestimated on AP pelvis radiographs as a result of inaccurate patient positioning, imprecise magnification, and radiographic beam divergence. The aim of the present study was to evaluate the accuracy and reliability of predicting three-dimensional (3-D) FO from standardised AP pelvis radiographs. MethodsIn a retrospective cohort study, pre-operative AP pelvis radiographs, AP hip radiographs and CT scans of a consecutive series of 345 patients (345 hips, 146 males, 199 females, mean age 60 (range: 40–79) years, mean body-mass-index 27 (range: 19–57)kg/m2) with primary end-stage hip OA were reviewed. Patients were positioned according to a standardised protocol and all images were calibrated. Using validated custom programmes, FO was measured on corresponding radiographs and CT scans. Measurement reliability was evaluated using intra-class-correlation-coefficients. To predict 3-D FO from AP pelvis measurements and to assess the accuracy compared to CT, the entire cohort was randomly split into subgroups A and B. Gender specific regression equations were derived from group A (245 patients) and the accuracy of prediction was evaluated in group B (100 patients) using Bland–Altman plots. ResultsIn the entire cohort, mean FO was 39.2mm (95%CI: 38.5–40.0mm) on AP pelvis radiographs, 44.1mm (95%CI: 43.4–44.9mm) on AP hip radiographs and 44.6mm (95%CI: 44.0–45.2mm) on CT scans. In group B, we observed no significant difference between gender specific predicted FO (males: 48.0mm, 95%CI: 47.1–48.8mm; females: 42.0mm, 95%CI: 41.1–42.8mm) and FO as measured on CT (males: 47.7mm, 95%CI: 46.1–49.4mm, p=0.689; females: 41.6mm, 95%CI: 40.3–43.0mm, p=0.607). ConclusionsThe present study suggests that FO can be accurately and reliably predicted from AP pelvis radiographs in patients with primary end-stage hip osteoarthritis. Our findings support the surgeon in pre-operative templating on AP-pelvis radiographs and may improve offset and limb length restoration in THA without the routine performance of additional radiographs or CT.

Assessment of Total Hip Arthroplasty by Means of Computed Tomography 3D Models and Fracture Risk Evaluation

Total hip arthroplasty (THA) can be achieved by using a cemented or noncemented prosthesis. Besides patient's age, weight, and other clinical signs, the evaluation of the quality of the bones is a crucial parameter on which orthopedic surgeons base the choice between cemented and noncemented THA. Although bone density generally decreases with age and a cemented THA is preferred for older subjects, the bone quality of a particular patient should be quantitatively evaluated. This study proposes a new method to quantitatively measure bone density and fracture risk by using 3D models extracted by a preoperative computed tomography (CT) scan of the patient. Also, the anatomical structure and compactness of the quadriceps muscle is computed to provide a more complete view. A spatial reconstruction of the tissues is obtained by means of CT image processing, then a detailed 3D model of bone mineral density of the femur is provided by including quantitative CT density information (CT must be precalibrated). A finite element analysis will provide a map of the strains around the proximal femur socket when solicited by typical stresses caused by an implant. The risk for structural failure due to press-fitting and compressive stress during noncemented THA surgery was estimated by calculating a bone fracture risk index (ratio between actual compressive stress and estimated failure stress of the bone). A clinical trial was carried out including 36 volunteer patients (ages 22-77) who underwent unilateral THA surgery for the first time: 18 received a cemented implant and 18 received a noncemented implant. CT scans were acquired before surgery, immediately after, and after 12 months. Bone and quadriceps density results were higher in the healthy leg in about 80% of the cases. Bone and quadriceps density generally decrease with age but mineral density may vary significantly between patients. Preliminary results indicate the highest fracture risk at the calcar and the lowest at the intertrocanteric line, with some difference between patients. An analysis of the results suggest that this methodology can be a valid noninvasive decision support tool for THA planning; however, further analyses are needed to tune the technique and to allow clinical applications. Combination with gait analysis data is planned.

Rasche Prototypen-Technik in der präoperativen Planung der totalen Hüft-Arthroplastie mit speziell angefertigten femoralen Komponenten

One of the problems we come across in our practice is related to the patients with very disturbed anatomy structures of the hip joint due to the incompatibilities between standard implants and host bone. These incompatibilities are usually represented by an extreme narrowing of the femoral medullary canal or sometimes by disturbances of the diaphyseal anatomical axis of the femur and are encountered in younger patients who usually require pressfit uncemented implants in order to achieve a normal survivorship of the implant. In these particular cases, customized prosthetic components may represent an alternative, but there are still controversies regarding the biomechanical behavior of these implants compared to the standard components.The use of prototypes for the receiving bone and for the prosthetic implant, respectively, is helpful in the validation process of the optimal model of custom implant by eliminating those designs that cannot be inserted into the medullar canal or those that could injure the receiving bone structure.Prototype design and execution for both the implant and femoral structure by means of rapid prototyping technology represents a major advantage in carrying out the preoperative planning of this type of surgical interventions due to the possibility of preoperative simulation of the insertion of femoral component into the medullar canal.

Evaluation of Biomechanical Models for the Planning of Total Hip Arthroplasty

Evaluation of Biomechanical Models for the Planning of Total Hip Arthroplasty

Accuracy and Reliability of Digital Templating in Primary Total Hip Arthroplasty

Digital templating has been used as a method of reducing hospital costs by eliminating the need for acetate films. Digital templating techniques have been used for preoperative planning for total hip arthroplasty (THA). Fifty-four patients who underwent THA were selected for the study. Templating was performed using acetate templating overlays and digital templating software. Acetabular component sizes were accurate in 96% of patients using the acetate method and in 93% using the digital method. Femoral component sizes were accurate in 80% in the acetate method and 74% in the digital method. Digital templating is safe and effective for preoperative planning for THA.