The Accuracy and Reliability of Preoperative Templating for Metal-on-Metal Hip Resurfacing

The purposes of this study were to evaluate the accuracy and reliability of preoperative templating on conventional radiographs (CRs) for metal-on-metal hip resurfacing and to determine the factors affecting the accuracy. Four observers templated 80 CRs on 2 separate occasions in a blinded fashion. Eight independent variables were evaluated to investigate their effect on the accuracy of templating. The overall accuracy of templating within one size of the actual component was 80.6% for the femoral component and 98.5% for the acetabular component. Overall, the intraobserver and interobserver reliability was fair to substantial (κ = 0.22-0.61). Using multiple regression analysis, surgical time was the only factor that affected the accuracy of predicting the size of the acetabular component (P = .019). We conclude that CR templating for metal-on-metal hip resurfacing is a useful method for preoperative planning of the sizes of the respective implants and that surgeon experience does play a significant role in the accuracy of predicting component size during templating.     

Common Errors in the Execution of Preoperative Templating for Primary Total Hip Arthroplasty

We reviewed 75 primary total hip arthroplasty preoperative and postoperative radiographs and recorded limb length discrepancy, change in femoral offset, acetabular position, neck cut, and femoral component positioning. Interobturator line, as a technique to measure preoperative limb length discrepancy, had the least amount of variance when compared with interteardrop and intertuberosity lines (Levene test, P = .0527). The most common error in execution of preoperative templating was excessive limb lengthening (mean, 3.52 mm), primarily due to inferior acetabular cup positioning (Pearson correlation coefficient, P = .036). Incomplete medialization of the acetabular component contributed the most to offset discrepancy. The most common errors in the execution of preoperative templating resulted in excessive limb lengthening and increased offset. Identifying these errors can lead to more accurate templating techniques and improved intraoperative execution.     

Assessment of Accuracy and Reliability in Preoperative Templating for Hip Resurfacing Arthroplasty

The current study investigated the accuracy and reliability of hip resurfacing component selection based on digital preoperative templating. Four surgeons made a template of preoperative radiographs on 2 occasions for acetabular and femoral components in 50 randomly selected hip resurfacing patients. Component selection reliability was variable among surgeons (κ = 0.16-0.73) and fair between surgeons (κ = 0.23-0.32). The average percentage of agreement for the acetabular component was 47% (range, 32%-64%) and for the femoral component was 54% (range, 38%-70%). Surgeons tended to underestimate implant size if the correct implant was not chosen (acetabular, 29%; femoral, 32%). Selection of an undersized femoral component may lead to femoral neck notching or varus implant alignment. This study emphasizes the need for intraoperative verification of preoperative templating results to ensure optimal implant selection in hip resurfacing.     

Accuracy of a New Digital Templating Method for Total Hip Arthroplasty Using Picture Archiving and Communication System (PACS) and iPhone Technology: Comparison With Acetate Templating on Digital Radiography

BackgroundPreoperative templating for total hip arthroplasty (THA) on digital radiography can be achieved using templating software or hybrid methods (acetate templates overlaid on digital images). No studies have examined templating with a mobile phone. We evaluated the accuracy and reproducibility of a new digital templating method using the picture archiving and communication system (PACS) and iPhone, compared with the hybrid method for cementless THA.MethodsA total of 113 hip radiographs were retrospectively templated by three observers. For the digital method, a circle was drawn on the acetabulum using PACS to represent the cup. The photograph of the computer screen was taken with an iPhone and imported into the Keynote presentation software. The femoral stem was then templated with transparent digital templates, which had been digitized from acetate templates. For the hybrid method, an acetate template was placed over the onscreen digital radiographs. Templated results were compared with the actual components used.ResultsThe digital method was more accurate than the hybrid method to predict ±1 size of femoral stem [93.8% (106 hips) vs 84.1% (95 hips), P = .032] and offset [90.3% (102 hips) vs 75.2% (85 hips), P = .004)]. The accuracies of digital and hybrid techniques were comparable with predict ±1 size for acetabular cup [92.9% (105 hips) vs 89.4% (101 hips), P = .483] and neck length [98.2% (111 hips) vs 96.5% (109 hips), P = .683]. Both techniques had substantial to almost perfect agreement for intraobserver and interobserver reliability.ConclusionDigital templating using PACS and iPhone is accurate and reproducible for predicting implant size of cementless THA.     

Anthropometric method for estimating component sizes in total hip arthroplasty

BACKGROUNDPreoperative templating is essential in total hip arthroplasty (THA) as it not only helps to facilitate the correct implant type and size but also determines the post-operative biomechanics. Templating is also increasingly important from a medico-legal perspective and recommended in the British Orthopaedic Association Guide to Good Practice. Although templating has become increasingly digitised, there are no simple anthropometric models to predict implant sizes in the absence of digital methods.AIMTo assess the accuracy of using an easily obtainable measurement (shoe size) to predict component sizes in THA compared with digital templating.METHODSDigital radiographs from a cohort of 102 patients (40 male, 62 female) who had undergone uncemented or hybrid THA at a single centre were retrospectively templated to desired cup and stem sizes using TraumaCad^®. We compared the templated size to the actual size of the implant and assessed if there was any correlation with the patient’s shoe size.RESULTSStatistically significant positive correlations were observed between: shoe size and templated cup size (ρ = 0.92, P < 0.001); shoe size with implanted cup size (ρ = 0.71, P < 0.001); shoe size and templated stem size (ρ = 0.87, P < 0.001); and shoe size with implanted stem size (ρ = 0.57, P < 0.001). Templated and implanted acetabular cup sizes were positively correlated (ρ = 0.76, P < 0.001) and were exact in 43.1% cases; 80.4% of implanted cup sizes were within 1 size (+/- 2 mm) of the template and 100% within 2 sizes (+/- 4 mm). Positive correlation was also demonstrated between templated and implanted femoral stem sizes (ρ = 0.69, P < 0.001) and were exact in 52.6% cases; 92.6% were within 1 size of the template and 98% within 2 sizes.CONCLUSIONThis study has shown there to be a significant positive correlation between shoe size and templated size. Anthropometric measurements are easily obtainable and can be used to predict uncemented component sizes in the absence of digital methods.     

A Comparison of Component Positioning Between Fluoroscopy-Assisted and Robotic-Assisted Total Hip Arthroplasty

BackgroundThis single-surgeon retrospective study examined a consecutive series of direct anterior approach total hip arthroplasties (THAs). Differences for the accuracy of acetabular component placement, leg length discrepancy, femoral offset, and absolute global offset difference were measured for patients who underwent hip replacement surgery with either fluoroscopic or robotic guidance.MethodsOne hundred THAs were included in both the fluoroscopically guided and robotically guided groups in the study. The program TraumaCad was used to analyze the preoperative and 6-week postoperative standing anteroposterior pelvic radiographs used in this study to evaluate the accuracy of component positioning.ResultsRobotic-guided surgery demonstrated a small improvement in acetabular inclination error, 3.8° average robotic error vs 4.63° average fluoroscopic error (P < .01). There was no statistically significant difference in accuracy for acetabular anteversion, leg length discrepancy, femoral offset, or global offset difference between the 2 groups. There was also no significant difference in the placement of acetabular components into the Lewinnek safe zone or Callanan safe zone. Both fluoroscopically guided and robotically guided THA patients had similar patterns of error, with excessive anteversion and inclination being more common than inadequate anteversion or inclination.ConclusionThe findings from our study question the use of haptic robotic guidance during direct anterior approach THA when compared to fluoroscopic guidance.     

Digital templating facilitates accurate leg length correction in total hip arthroplasty

Digital templating of pre-operative radiographs is increasingly utilised by surgeons before total hip arthroplasty (THA) as part of an adequate preoperative preparation to minimise complications. Templating can accurately predict the required implant sizes but its use in facilitating correction of leg length discrepancy (LLD) has been underreported in the literature. We performed a retrospective analysis of a cohort of consecutive patients undergoing primary THA. A comparison was made of the implant sizes templated with actual sizes used. In addition, pre-operative leg-length discrepancy (LLD) was noted and compared with intra-operative measurement of LLD correction and post-operative LLD correction seen on postoperative radiographs, as measured by two independent observers. Statistical analysis was performed to investigate the correlation between pre- and postoperative measurements. Fifty nine patients that had primary THA were investigated, 42 with hybrid replacements, 17 with cemented replacements. Spearman's-rho 2-tailed correlation between templated and implanted femoral offset, stem size and acetabular cup size was 0.850, 0.709 and 0.834 respectively (p < 0.01 for all). Correlation between the pre-operative templated LLD and the measured post-operative corrected LLD was 0.841 (p < 0.01). No difference existed between hybrid and cemented hips or the presence or absence of a contralateral hip replacement. In this study, templating for THA was significantly accurate in predicting the required femoral and acetabular implant sizes. In addition, the correction of pre-operative LLD was accurately performed, as evidenced by measurement on post-operative films. The results of this study support the pre-operative digital templating of radiographs in total hip arthroplasty.     

Assessment of Accuracy of Marker Ball Placement in Pre-operative Templating for Total Hip Arthroplasty

We report the accuracy of positioning of the calibration ball in the process of pre-operative templating for total hip arthroplasty (THA). The ball should be placed in the coronal plane of the hip to provide suitable accuracy. We reviewed 112 post-operative THA radiographs where a calibration ball had been placed. We templated the femoral head size of the implant after calibrating the templating system from the ball. The calibrated femoral head diameter was compared to the known prosthetic head size. A percentage error was calculated. Overall, incorrect placement of the calibration ball resulted in a mean percentage error in templating of 6.8% (median 5.7%; range 0–26%). Such error carries implications with the templating process and may result in incorrect component sizes, leg lengths and offset.     

A Comparison of Acetate vs Digital Templating for Preoperative Planning of Total Hip Arthroplasty : Is Digital Templating Accurate and Safe?

The purposes of this study were to compare the accuracy of acetate and digital templating for primary total hip arthroplasty (THA) and to determine if digital templating is safe. Preoperative planning was performed on 50 consecutive preoperative radiographs during 2005. Templating results were compared with the actual hip implants used. Interrater reliability of acetate templating and accuracy of acetate and digital templating were recorded. Digital measurement overestimated acetabular size (P < .001) and underestimated the femoral size (P = .03). The absolute errors were larger for digital compared with acetate templating; however, mean absolute errors did not differ significantly (acetabulum, P = .090; femur, P = .114). Acetate and digital templating can accurately predict the size of THA implants. Digital templating was determined to be acceptably safe for preoperative planning of primary THA operations.     

The accuracy of digital templating: a comparison of short-stem total hip arthroplasty and conventional total hip arthroplasty

Purpose

Selection of the correct femoral stem size is crucial in total hip arthroplasty for an uncomplicated implantation and good initial stability. Pre-operative templating has been shown to be a valuable tool in predicting the correct implant size. For short-stem total hip arthroplasty (SHA), which recently is increasingly used, it is unknown if templating can be performed as reliable as conventional total hip arthroplasty (THA).

Methods

A total of 100 hip arthroplasties, 50 with SHA and 50 with THA, were templated by four orthopaedic surgeons each. The surgeons had different levels of professional experience and performed a digital template of the acetabular and femoral component on the pre-operative radiographs. The results were compared with the truly inserted implant size.

Results

For the femoral stems the average percentage of agreement (±1 size) was 89.0 % in SHA and 88.5 % in THA. There was no significant difference among surgeons in the accuracy of templating the correct stem size and no significant difference between templating SHA and THA. For the acetabular component the average percentage of agreement (±1 size) was 75.8 %. However, the more experienced surgeons showed a significant higher accuracy for templating the correct cup size than the less experienced surgeons.

Conclusion

Digital templating of SHA can predict the stem sizes as accurately as conventional THA. Therefore digital templating is also recommendable for SHA, as it helps to predict the implant size prior to surgery and thereby might help to avoid complications.     

Effect of Body Mass Index on Digital Templating for Total Hip Arthroplasty

Background

Digital templating is becoming more prevalent in orthopedics. Recent investigations report high accuracy using digital templating in total hip arthroplasty (THA); however, the effect of body mass index (BMI) on templating accuracy is not well described.

The Use of Patient-Specific Instrumentation Improves the Accuracy of Acetabular Component Placement

Preoperative assessment of acetabular pathology, planning of bone preparation, and implant placement using current imaging, templating, and surgical techniques are imprecise, frequently resulting in component malposition. This study compared the accuracy of 2 surgical approaches: (1) standard preoperative imaging and instrumentation and (2) a novel 3-dimensional computed tomography scan–based preoperative planning software linked to patient- and implant-specific instrumentation (PSI) for placing acetabular components. The PSI group resulted in a significant improvement (P < .05) in the average deviation of implant position (actual vs planned) for version, inclination, and total offset. Fewer clinically relevant screw perforations were observed in the PSI group. This study shows proof of concept and justifies a clinical trial comparing PSI technology with standard surgical techniques.     

A Comparison of Revision Rates for Dislocation and Aseptic Causes Between Dual Mobility and Large Femoral Head Bearings in Primary Total Hip Arthroplasty With Subanalysis by Acetabular Component Size: An Analysis of 106,163 Primary Total Hip Arthroplasties

BackgroundDual mobility (DM) and large femoral head bearings (≥36 mm) both decrease the risk of dislocation in total hip arthroplasty (THA). There is limited comparable data in primary THA. This study compared the revision rates for dislocation and aseptic causes between DM and large femoral heads and subanalyzed by acetabular component size.MethodsData from the Australian Orthopedic Association National Joint Replacement Registry were analyzed for patients undergoing primary THA for osteoarthritis from January 2008 (the year of first recorded DM use) to December 2019. All DM and large femoral head bearings were identified. The primary outcome measure was the cumulative percent revision (CPR) for dislocation and for all aseptic causes. The results were adjusted by age, sex, and femoral fixation. A subanalysis was performed stratifying acetabular component diameter <58 m and ≥58 mm.ResultsThere were 4942 DM and 101,221 large femoral head bearings recorded. There was no difference in the CPR for dislocation (HR = 0.69 (95% CI 0.42, 1.13), P = .138) or aseptic causes (HR = 0.91 (95% CI 0.70, 1.18), P = .457). When stratified by acetabular component size, DM reduced the CPR for dislocation in acetabular component diameter <58 mm (HR = 0.55 (95% CI 0.30, 1.00), P = .049). There was no difference for diameter ≥58 mm. There was no difference in aseptic revision when stratified by acetabular component diameter.ConclusionThere is no difference in revision rates for dislocation or aseptic causes between DM and large femoral heads in primary THA. When stratified by acetabular component size, DM reduces dislocation for acetabular component diameter <58 mm.Level of EvidenceLevel III.     

The accuracy of preoperative templating in cementless total hip arthroplasty

We evaluated the accuracy and clinical usefulness of preoperative templating in 109 cementless total hip arthroplasties. The size of the prosthesis was exactly predicted in 46 (42.2%) acetabular and 75 (68.8%) femoral components. The accuracy increased to greater than 90% if the prosthesis size was within 1 or 2 sizes (above or below) for femoral component and acetabular components, respectively. Having a contralateral total hip arthroplasty as a guide for preoperative templating was associated with greater accuracy in predicting the femoral component size only. Eighty-eight percent of the acetabular components were oriented inside the presumed safe range for inclination; 42% of the acetabular components were in the presumed safe range of anteversion. The mean postoperative leg length discrepancy was 0.9 +/- 6.8 mm; 93.5% had a discrepancy within 10 mm.     

Accuracy of Preoperative Templating in Total Hip Arthroplasty With Special Focus on Stem Morphology: A Randomized Comparison Between Common Digital and Three-Dimensional Planning Using Biplanar Radiographs

BackgroundAccurate preoperative planning is a key component of successful total hip arthroplasty (THA). The purpose of the present study was to compare the accuracy and reliability of three-dimensional (hipEOS) and common digital two-dimensional (TraumaCad) templating with special focus on stem morphology.Methods51 patients undergoing THA were randomized to two groups. Preoperative planning was performed on 23 patients with hipEOS (3D) and on 28 patients with TraumaCad (2D) planning software. Planning results were compared with the implanted component size. Inter- and intraobserver reliability as well as planning accuracy of both planning methods with special focus on straight and short stem design were recorded.ResultsIntraobserver reliability of both planning methods was good for component planning (ICC_2,1: 0.835-0.967). Interobserver ICC_2,1 for stem and cup planning were higher for 3D templating (3D ICC_2,1: 0.906-0.918 vs. 2D ICC_2,1: 0.835-0.843). Total stem and cup size predictions were within 2 sizes for 3D and within 3 sizes for 2D planning. Comparing short stem planning accuracy of both planning methods, absolute difference between implanted and planned component size was significantly lower in 3D planning (P = .029). There was no significant difference in straight stem (P = .935) and cup (P = .954) planning accuracy.ConclusionOur findings suggest that 3D templating with hipEOS software has a good overall reliability and may have a better planning accuracy of short stem prostheses than digital templating with TraumaCad software. Assuming that the number of implanted short stem prostheses will further increase in coming years, a more precise planning with 3D technique can contribute to improve surgery outcome.     

Determination of accuracy of preoperative templating of noncemented femoral prostheses

The purpose of this study was to determine the accuracy of preoperative templating of primary, noncemented femoral components. A retrospective review of charts and radiographs was performed on 74 hips in 64 patients who had undergone either noncemented total hip arthroplasty (THA) or placement of an endoprosthesis (including bipolar). Preoperative radiographs were templated by a total joint arthroplasty attending surgeon, a senior orthopaedic resident, and a junior resident. The templated size corresponded to the actual femoral implant used in approximately 50% of cases. When femoral prostheses within one size above or below the templated size were included, the accuracy of preoperative templating rose to 88–95%. When implants within two sizes of the templated size were included, the accuracy approached 100%. Factors associated with discrepancies in the size of femoral stem used included placement of an undersized implant, presence of metal hardware that obscured the ability to template accurately, proximal bone deformity, sclerotic bone, acute femoral neck fracture, and inadequate preoperative radiographs. The accuracy of templating increased gradually with the level of training. The most experienced investigator was able to template within one size of the actual implant used in 95% of cases, compared with 88% and 82% for the less experienced investigators. Acute femoral neck fractures and proximal bone deformity were associated with the largest discrepancies in templated sizes.     

Digital pre-operative templating is more accurate in total hip replacement compared to analogue templating

We prospectively evaluated the accuracy of digital compared to analogue pre-operative templating in 50 consecutive primary hip replacements between April 2006 and June 2007. The senior author pre-operatively templated implant size using TraumaCad (Orthocrat Limited, Israel). Thirty-one Exeter primary hip and 19 hybrid hip replacements were performed. Hips were templated using radiographs calibrated against a spherical metal ball. For each hip, an AP pelvis view was used. Acetabular implants used were either Trident PSL or Exeter contemporary cup (Stryker). Femoral stem was Exeter (Stryker). Predicted implant sizes were documented. Post-operatively, the predicted implant size was compared to the implanted components. All post-operative films showed good fit of components and there were no intraoperative or post-operative fractures. The intra-rater reliability (ICC) of analogue templating was 0.96 and digital templating was 0.90. Accurate templating score for acetabular cup was 46% (digital) 43% (analogue), femoral offset was 80% (digital) 70% (analogue), femoral stem was 76% (digital) 60% (analogue). The differences between templating and actual implant sizes were plotted in Bland–Altman plot. Digital templating produced narrower confidence interval compared to analogue templating. Digital templating proved to be statistically, significantly more accurate compared to analogue templating for acetabluar cup and femoral stem. Our data indicate that digital templating is more reliable in predicting actual implant sizes for total hip arthroplasty when performed by the operating surgeon.     

Are There Gender-Specific Errors in Restoration of Hip Biomechanics That Affect Outcome Following Total Hip Arthroplasty?

BackgroundThere are morphologic differences between males and females, which are currently underappreciated during total hip arthroplasty. We sought to assess whether these differences affected surgical process and subsequent outcome.MethodsA total of 123 patients (75 females, 48 males) had preoperative and 1-year Oxford Hip Score (OHS) and pain scores recorded. Acetabular height and offset, femoral height and offset, and acetabular floor depth were measured on preoperative and postoperative X-rays and then compared to their normal opposite hip. Discrepancies between the replaced and normal hip X-ray measurements were then correlated with changes (the delta gain) in preoperative and 1-year postoperative OHS and pain scores.ResultsPostoperatively, females had significantly greater femoral height discrepancy (P = .023) which meant they were lengthened. This led to a reduced delta gain in OHS and pain score at 1 year. Males lost more acetabular offset than females (P = .002), leading to a medialized acetabular center and subsequently reduced delta gain in pain score at 1 year (P = .017).ConclusionFemales have a smaller femur leading to a bias toward a conservative (higher) neck cut compared with males and potential for femoral lengthening. Males have a greater acetabular floor depth compared with females and thus reaming to the true floor results in greater loss of acetabular offset. In this series, both scenarios led to reduced improvement in OHS and/or pain scores at 1 year.     

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

Background

The 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).

Digital templating in primary total hip and knee arthroplasty

The use of digital radiography is becoming more prevalent in orthopedics. This transition impacts the ability to preoperatively plan for implants in total hip arthroplasty (THA) and total knee arthroplasty (TKA). This article reports on the clinical success of digital templating using the Advanced Case Plan (Stryker Imaging, Flower Mound, Texas) system in primary THA and TKA. Digital radiographs of 269 consecutive patients undergoing primary THA (93 cases) or TKA (176 cases) were templated using the Advanced Case Plan digital software package. A 25.4-mm metallic sphere was used as a calibrating marker. Anteroposterior hip and lateral knee radiographs were digitally templated preoperatively and compared to the actual size of the implants at the time of surgery. The accuracy of calibrating images using the metallic sphere was validated by measuring the diameter of femoral heads on 25 postoperative hip radiographs. Digital templating was accurate in predicting the correct implant size in 58.5% of THAs and 66% of TKAs. In 93% of THAs and 98.5% of TKAs, preoperative templating was within 1 size of the final implant. There were no cases in which the predicted implant size varied from the final components by >2 sizes. Calibrating the image using the metallic sphere marker was found to be highly accurate, predicting the correct femoral head size within 1.5 mm in all 25 cases (7 hemiarthroplasties and 18 THAs). Digital templating is an effective means for predicting the size of THA and TKA components, thus remaining a viable option as we transition into the modern era of digital radiography. Future studies will evaluate interobserver reliability and the impact of level of training on templating accuracy.