EOS Imaging is Accurate and Reproducible for Preoperative Total Hip Arthroplasty Templating

BackgroundTemplating is a critical part of preoperative planning for total hip arthroplasty (THA). The accuracy of templating on images acquired with EOS is unknown. This study sought to compare the accuracy and reproducibility of templating for THA using EOS imaging to conventional digital radiographs.MethodsForty-three consecutive primary unilateral THAs were retrospectively templated, six months postoperatively, using preoperative 2D EOS imaging and conventional radiographs. Two blinded observers templated each case for acetabular and femoral component size and femoral offset. The retrospectively templated sizes were compared to the sizes selected during surgery. Interobserver agreement was calculated, and the influence of demographic variables was explored.ResultsEOS templating predicted the exact acetabular and femoral size in 71% and 66% of cases, respectively, and to within one size in 98% of cases. The acetabular and femoral component size was more likely to be templated to the exact size using EOS compared to conventional imaging (P < .05). The femoral component offset choice was accurately predicted in 83% of EOS cases compared to 80% of conventional templates (P = .341). Component size and offset were not influenced by patient age, gender, laterality, or BMI. Interobserver agreement was excellent for acetabular (Cronbach’s alpha = 0.94) and femoral (Cronbach’s alpha = 0.96) component size.ConclusionsPreoperative templating for THA using EOS imaging is accurate, with an excellent interobserver agreement. EOS exposes patients to less radiation than traditional radiographs, and its three-dimensional applications should be explored as they may further enhance preoperative plans.     

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 Accuracy of Digital Templating in Uncemented Total Hip Arthroplasty

We analyzed the reproducibility and reliability of computer templating in primary uncemented total hip arthroplasties as compared to standard onlay templating techniques with hardcopy radiographs from a digital source. Digital templating showed good intraobserver and interoberserver reliability with intraclass correlation coefficient values greater than 0.7. Using computer templating, prediction of sizing to within 1 size was 85% accurate for femoral stem sizing and 80% accurate for acetabular sizing. Using onlay templating, prediction of sizing to within 1 size was 85% accurate for femoral sizing and 60% accurate for acetabular sizing. We conclude that the introduction of digital templating has significant benefits in preoperative planning for total hip arthroplasty over onlay templating.     

Scaling Marker Position Determines the Accuracy of Digital Templating for Total Hip Arthroplasty

Background

Digital templating systems foster patient-specific measurements for preoperative planning.

Questions/Purposes

We aim (1) to verify the accuracy of a templating system, (2) to describe the effects of scaling marker position on the accuracy of digital templating of the hip, and (3) to provide a practical guide for scaling marker position using patient body mass index (BMI).

Methods

A scaling sphere was placed in five positions along the anterior-posterior axis of an acetabular implant and pelvis phantom, and x-rays were obtained. Each radiograph was templated for the acetabular component and recorded. A retrospective review identified CT scans of preoperative hip arthroplasty cases. The center of the greater trochanter was calculated from these CT scans as the percent distance from the anterior thigh and recorded with the patient’s BMI.

Results

By centering the scaling sphere on the acetabular component, an accurate cup size was achieved. A difference of 3.5 cm in sphere placement resulted in a full cup size magnification error. Positioning the scaling sphere at the level of the pubic symphysis resulted in a difference of four cup sizes. This patient population had an average BMI of 28.72 kg/m² (standard deviation 6.26 kg/m²) and an average position of the center of the greater trochanter of 51% (standard deviation of 6%) from the anterior surface of thigh.

Conclusions

Digital templating relies on scaling marker position to accurately estimate implant size. Based on the findings in this study, scaling markers for hip imaging should be placed laterally, mid-thigh in the anterior-posterior direction for patients with a BMI between 25 and 40 kg/m². If abnormal hip anatomy or extremes of BMI are discovered, then scaling sphere positioning should be optimized on a case-by-case basis. Digital templating systems for total hip arthroplasty must use precisely placed scaling markers at the level of the hip joint to allow for accurate implant size estimation.

     

Biplanar Low-Dose Radiography Is Accurate for Measuring Combined Anteversion After Total Hip Arthroplasty

HSS Journal ® - Acetabular component position alone has not been predictive of stability after total hip arthroplasty (THA). Combined anteversion of the acetabulum and femur has the potential...     

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.     

The Cost of an Episode of Care in a Total Knee Arthroplasty Patient Is More Than a Total Hip Arthroplasty Patient Within an Alternative Payment Model

BackgroundAlternative payment models were set up to increase the value of care for total joint arthroplasty. Currently, total knee arthroplasty (TKA) and total hip arthroplasty (THA) are reimbursed within the same bundle. We sought to determine whether it was appropriate for these cases to be included within the same bundle.MethodsThe data were collected from consecutive patients in a bundled payment program at a single large academic institution. All payments for 90 days postoperatively were included in the episode of care. Readmission rates, demographics, and length of stay were collected for each episode of care.ResultsThere was a significant difference in cost of episode of care between TKA and THA, with the average TKA episode-of-care cost being higher than the average THA episode-of-care cost ($25803 vs $23805, P < .0001). There was a statistically significant difference between the 2 groups between gender, race, medical complexity, disposition outcome, and length of stay. The TKA group trended toward a lower readmission rate (5.3%) compared to the THA group (6.6%).ConclusionThe cost of an episode of care for patients within the bundled payment model is significantly higher for patients undergoing TKA compared with those undergoing a THA. This should be taken into consideration when determining payment plans for patients in alternative payment plans, along with other aspects of risk that need to be considered in order to allow for hospitals to be successful under the bundled payment model.     

人工全髋关节置换术术前的模板测量与术后评估

目的通过全髋关节置换术术前模板测量与术后相关因素的评估,探讨全髋关节置换术术前模板测量的准确性和重要性.方法 2003年10月至2004年9月,选取因特发性股骨头无菌性坏死行单侧全髋关节置换术的19 例病人作为研究对象,其中男11 例,女8 例.年龄40～74 岁,平均58.7 岁.术前通过临床查体及骨盆X光正位片,对双下肢不等长和双侧股骨偏心距的差异程度进行测量和评估.再利用模板测量,预测髋臼及股骨假体的型号及置入位置,估计股骨颈的截骨水平以及预定出平衡双下肢长度的计划.术后对这些指标进行评估和验证.结果 19 例患者中术前有15 例存在双下肢不等长,术后这些患者的下肢不等长情况都有显著改善.此19 例患者双下肢长度差均值由术前8.4 mm减小到4.4 mm,73.7%的患者术后双下肢长度差异在5 mm之内.双侧股骨偏心距差均值由术前6.3 mm减小到3.0 mm.术前模板测量出的假体型号与实际应用的假体比较,髋臼假体符合率为52.6%,股骨柄假体符合率为63.2%.结论人工全髋关节置换术术前精确的模板测量对于重建髋关节结构和功能及恢复下肢长度具有重要的意义.     

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.     

Surgeons Experience Greater Cardiorespiratory Strain and Stress During Total Hip Arthroplasty Than Total Knee Arthroplasty

BackgroundTotal hip arthroplasty (THA) and total knee arthroplasty (TKA) are physically demanding, with a high prevalence of work-related injuries among arthroplasty surgeons. It is unknown whether there are differences in cardiorespiratory output for surgeons while performing THA and TKA. The objective of this study is to characterize whether differences in surgeon physiological response exist while performing primary THA vs TKA.MethodsThis is a prospective cohort study including 3 high-volume, fellowship-trained arthroplasty surgeons who wore a smart garment that recorded cardiorespiratory data on operative days during which they were performing primary conventional TKA and THA. Variables collected included patient body mass index (BMI), operative time (minutes), heart rate, heart rate variability, respiratory rate, minute ventilation, and energy expenditure (calories).ResultsSeventy-six consecutive cases (49 THAs and 27 TKAs) were studied. Patient BMI was similar between the 2 cohorts (P > .05), while operative time was significantly longer in TKAs (60.4 ± 12.0 vs 53.6 ± 11.8; P = .029). During THA, surgeons had a significantly higher heart rate (95.7 ± 9.1 vs 90.2 ± 8.9; P = .012), energy expenditure per minute (4.6 ± 1.23 vs 3.8 ± 1.2; P = .007), and minute ventilation (19.0 ± 3.0 vs 15.5 ± 3.3; P < .001) compared to TKA.ConclusionSurgeons experience significantly higher physiological strain and stress while performing THA. While scheduling THAs and TKAs, surgeons should consider the higher physical demand associated with THAs and ensure adequate personal preparation and sequence of cases.     

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.     

Validation of CT‐Based Three‐Dimensional Preoperative Planning in Comparison with Acetate Templating for Primary Total Hip Arthroplasty

ObjectiveThis study aims to compare the accuracy of CT‐based preoperative planning with that of acetate templating in predicting implant size, neck length, and neck cut length, and to evaluate the reproducibility of the two methods.MethodsThis prospective study was conducted between August 2020 and March 2021. Patients who underwent elective primary total hip arthroplasty by a single surgeon were assessed for eligibility. The included patients underwent both acetate templating and CT‐based planning by two observers after the operation. Each observer conducted both acetate templating and CT‐based planning twice for each case. The outcome measures included the following: (1) the accuracy of surgical planning in predicting implant size, calcar length, and neck length, which was defined as the difference between the planned size and length and the actual size and length; (2) reproducibility of the two planning techniques, which were assessed by inter‐observer and intra‐observer reliability analysis; (3) the influence of potential confounding factors on planning accuracy, which was evaluated using generalized estimating equations.ResultsA total of 57 cases were included in the study. CT‐based planning was more accurate than acetate templating for predicting cup size (93% vs 79%, p < 0.001) and stem size (93% vs 75%, p < 0.001). When assessed by mean absolute difference, the comparison between acetate templating and CT‐based planning was 4.28 mm vs 3.74 mm (p = 0.122) in predicting neck length and 3.05 mm vs 2.93 mm (p = 0.731) in predicting neck cut length. In the inter‐observer reliability analysis, an intraclass correlation coefficient (ICC) of 0.790 was achieved for predicting cup size, and an ICC of 0.966 was achieved for predicting stem size using CT‐based planning. In terms of intra‐observer reliability, Observer 1 achieved an ICC of 0.803 for predicting cup size and 0.965 for predicting stem size in CT‐based planning. Observer 2 achieved ICC values of 0.727 and 0.959 for predicting cup and stem sizes, respectively. The average planning time was 6.48 ± 1.55 min for CT‐based planning and 6.12 ± 1.40 min for acetate templating (p = 0.015).ConclusionThe CT‐based planning system is more accurate than acetate templating for predicting implant size and has good reproducibility in total hip arthroplasty.     

全髋关节置换术下肢等长探讨

目的：探讨全髋关节置换术中如何准确达到下肢等长。方法：1996年5月-2001年7月有88例（92侧）髋关节置换术,男52例。女36例。年龄40-96岁。平均62.5岁。其中有76例下肢术前不等长。下肢长短状态分为可变下肢长度与不可变下肢长度。所有患者术前均进行X线片模板测试及下肢长度测量。不可变下肢长度（即患肢长短固定。不发生变化）术中采用克氏针标记骨盆。股骨之间距离,置入假体后根据实际情况调整长度;可变下肢长度（即术前患肢长短随时可发生变化）靠“三要素”来衡量,结果：术前患肢缩短1-4cm的76例患者中,术后仅有6例患肢延长0.5-2cm。2例患肢缩短1cm和2cm;术前12例下肢等长患者中有2例患肢延长1.5cm和2cm。结论：术前模板测试及下肢长短准确测量,术中通过克氏针标记骨盆与股骨技术及“三要素”衡量。能准确达到下肢等长。可以预防下肢不等长。     

Pelvic Tilt Is Minimally Changed by Total Hip Arthroplasty

Background

While surgical navigation offers the opportunity to accurately place an acetabular component, questions remain as to the best goal for acetabular component positioning in individual patients. Overall functional orientation of the pelvis after surgery is one of the most important variables for the surgeon to consider when determining the proper goal for acetabular component orientation.

Questions/Purposes

We measured the variation in pelvic tilt in 30 patients before THA and the effect of THA on pelvic tilt in the same patients more than a year after THA.

Methods

Each patient had a CT study for CT-based surgical navigation and standing and supine radiographs before and after surgery. Pelvic tilt was calculated for each of the radiographs using a novel and validated two-dimensional/three-dimensional matching technique.

Results

Mean supine pelvic tilt changed less than 2°, from 4.4° ± 6.4° (range, ?7.7° to 20.8°) before THA to 6.3° ± 6.6° (range, ?5.7° to 19.6°) after THA. Mean standing pelvic tilt changed less than 1°, from 1.5° ± 7.2° (range, ?13.1° to 12.8°) before THA to 2.0° ± 8.3° (range, ?12.3° to 16.8°) after THA. Preoperative pelvic tilt correlated with postoperative tilt in both the supine (r² = 0.75) and standing (r² = 0.87) positions.

Conclusions

In this population, pelvic tilt had a small and predictable change after surgery. However, intersubject variability of pelvic tilt was high, suggesting preoperative pelvic tilt should be considered when determining desired acetabular component positioning on a patient-specific basis.     

Leukocytosis Is Common After Total Hip and Knee Arthroplasty

Background  

Postoperative infection is a potentially devastating complication after THA and TKA. In the early postoperative period, clinicians often find nonspecific indicators of infection. Although leukocytosis may be a sign of a developing infection in the early postoperative period, it may also be part of a normal surgical response.     

Low Revision Rates at More Than 10 Years for Dual-Mobility Cups Cemented Into Cages in Complex Revision Total Hip Arthroplasty

BackgroundInstability and aseptic loosening are the two main complications after revision total hip arthroplasty (rTHA). Dual-mobility (DM) cups were shown to counteract implant instability during rTHA. To our knowledge, no study evaluated the 10-year outcomes of rTHA using DM cups, cemented into a metal reinforcement ring, in cases of severe acetabular bone loss. We hypothesized that using a DM cup cemented into a metal ring is a reliable technique for rTHA at 10 years, with few revisions for acetabular loosening and/or instability.MethodsThis is a retrospective study of 77 rTHA cases with severe acetabular bone loss (Paprosky ≥ 2C) treated exclusively with a DM cup (NOVAE STICK; Serf, Décines-Charpieu, France) cemented into a cage (Kerboull cross, Burch-Schneider, or ARM rings). Clinical scores and radiological assessments were performed preoperatively and at the last follow-up. The main endpoints were revision surgery for aseptic loosening or recurring dislocation.ResultsWith a mean follow-up of 10.7 years [2.1-16.2], 3 patients were reoperated because of aseptic acetabular loosening (3.9%) at 9.6 years [7-12]. Seven patients (9.45%) dislocated their hip implant, only 1 suffered from chronic instability (1.3%). Cup survivorship was 96.1% at 10 years. No sign of progressive radiolucent lines were found and bone graft integration was satisfactory for 91% of the patients.ConclusionThe use of a DM cup cemented into a metal ring during rTHA with complex acetabular bone loss was associated with low revision rates for either acetabular loosening or chronic instability at 10 years.