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 digital templating in total hip arthroplasty

Digital radiography is becoming the standard of care for many hospitals and clinics worldwide. The introduction of this new standard has led to the development of arthroplasty templating software. We sought to compare our results using the standard acetate method with the new software method. Our digital preoperative plan was accurate to within 1 size in 78% of the acetabular components and 90% of the femoral components. The manually templated plan was accurate to within 1 size in 67% of the acetabular components and 82% of the femoral components. There did not appear to be any correlation between body mass index and inaccuracies in the preoperative template. Digital templating is an accurate tool to preoperatively plan total hip arthroplasty. The accuracy demonstrated in this study should be achieved easily with any digital templating software. The benefit comes from the ability to scale the templates to the actual x-ray magnification. We expect that this improved accuracy over traditional acetate templating will enhance our ability to restore normal hip biomechanics.     

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.     

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.     

Precision of preoperative digital templating in total hip arthroplasty

The purpose of the present study was to evaluate the precision of digital templating in total hip arthroplasty (THA) and the influence of the surgeons' level of experience on the accuracy of preoperative planning. A retrospective review of digital computer planned THA's was performed on 169 hips. The preoperatively planned component sizes were compared to the sizes used in the operation. An exact agreement between planned and actually used size was achieved in 33.7% of the hips for the acetabular cups and 36% for the femoral stems. A prediction of +/- 1 size was reached in 77.5% for acetabular components and 82.3% for the femoral stem. On average, the acetabular components were planned approximately 0.9 sizes too large, the femoral stems 0.3 sizes too small. The accuracy of preoperative planning showed no differences according to the level of training of the planning surgeon. We state that the digital templating is useful to predict the implant size. However, 15 of the 169 planned components showed a difference of more than 2 sizes. Therefore, digital templating cannot fully replace intraoperative X-ray use.     

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.     

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.     

Accuracy of Digital Preoperative Templating in 100 Consecutive Uncemented Total Hip Arthroplasties : A Single Surgeon Series

Digital templating is an accurate method of assessing femoral and acetabular component sizes. This allows surgeons to foresee potential problems and also recognize an intraoperative error when a large discrepancy exists between a trial component and the templated size. Preoperative templating data of pelvic radiographs from 100 consecutive patients receiving uncemented implants were templated with Orthoview software (version 2.0CEN; Meridian Technique Ltd, Southampton, United Kingdom). Seventy-five percent of stems were templated to within 0.5 size, and 98%, to within 1 size. Eighty percent of cups were templated to within 2 mm, and 98%, to within 4 mm, and 62% of head length was accurately template. Seven patients were converted from a templated 132° to a 127° femoral prosthesis neck angle. The mean lower limb length discrepancy was + 0.05 mm (SD, 5.1 mm) postoperatively.     

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.     

股骨颈组配式假体在全髋关节置换术后偏心距重建中的作用

目的 探讨股骨颈组配式假体对全髋关节置换术后偏心距重建的意义.方法 对2009年6月至2012年6月使用股骨颈组配式假体行全髋关节置换术的75例患者进行回顾性研究,男42例,女33例;年龄44～83岁,平均(64.7±12)岁.左髋40例,右髋35例.术前Harris髋关节功能评分32～65分,平均(54±6)分.均采用M/L Taper with Kinectiv假体系统.术前应用模板技术预计假体大小及偏心距,术中实体测量,结合术前计划和术中情况选取大小合适的股骨颈假体,恢复偏心距,重建髋关节外展力臂.术后于X线片上测量偏心距及下肢长度.术后l、3、6、12个月及以后每年随访一次,采用Harris髋关节功能评分评价疗效.结果 股骨偏心距均得到重建,误差从-3.0～3.0 mm,平均(1.3±0.3)mm.双下肢长度差平均(3.0±0.8) mm.术后随访6～36个月,平均19.7个月.术后12周站立位髋关节外展角平均40°±10°;Harris髋关节功能评分65～94分,平均(86±13)分,与术前比较差异有统计学意义(t=19.360,P=0.000).末次随访时Harris髋关节功能评分78～98分,平均(95±15)分.随访期间未出现关节脱位和髋臼股骨撞击征病例.结论 使用股骨颈组配式假体可在不影响下肢长度的情况下恢复患肢的股骨偏心距,获得良好的髋关节外展肌力、活动度及稳定性,术后近期并发症发生率低.     

Predictive value of preoperative digital templating in THA depends on the surgical experience of the performing physician

Digital preoperative templating is increasingly used to predict the correct component size in total hip arthroplasty (THA). Experienced surgeons could avoid the new technique and rely on a digital template done by a younger colleague. We compared the accuracy of preoperative templating between orthopedic residents (group A) and an experienced orthopedic surgeon (group B). In 106 cases, the software-predicted component sizes of both groups were compared with component sizes placed surgically. An accurate prediction of the acetabular component was achieved in 63% of cases in group A compared with 88% of cases in group B (P=.001). Concerning the femoral component, accurate prediction was achieved in 89% in group A and 97% in group B (P=.021). If performed by an experienced orthopedic surgeon, digital templating is an accurate method to predict the prosthetic component size in THA.     

Biomechanics of large femoral heads: what they do and don't do

The stability and durability of total hip reconstruction is dependent on many factors that include the design and anatomic orientation of prosthetic components. An analysis of femoral component head size and acetabular component orientation shows an interdependency of these variables and joint stability. Increased femoral component head size can increase hip stability by increasing the prosthetic impingement-free range of hip motion and by increasing the inferior head displacement required before hip dislocation. Increasing the femoral head size from 22 mm to 40 mm increases the required displacement for dislocation by about 5 mm with the acetabular component at 45 degrees of abduction; however, increasing acetabular component abduction greatly diminishes this stability advantage of larger femoral heads. Vertical acetabular component orientation and femoral component head subluxation are each predicted to more than double the tensile stress with acetabular component polyethylene compared with components at 45 degrees of abduction. With a desirable acetabular component orientation, the use of larger femoral heads may result in improved joint stability and durable use of polyethylene. With high abduction acetabular component orientation, the use of larger femoral heads contributes little to joint stability and contributes to elevated stress within the polyethylene that may result in implant failure.     

Charnley total hip arthroplasty in Chinese patients less than 40 years old

Forty-seven total hip arthroplasties were reviewed in 33 Chinese patients who were <40 years old at the time of operation. The preoperative diagnosis was avascular necrosis in 40% of the hips. A Charnley prosthesis was inserted using early cementing techniques in every hip. The average follow-up was 14.9 years (range, 6.9-21.1 years). The mean preoperative Harris hip score was 43.8 (range, 26-74), and the mean score at latest follow-up was 87.7 (range, 74-99) for the surviving hips. Thirty hips (63%) were revised, and 1 hip was removed because of late deep infection. The main cause of failure was aseptic loosening of the acetabular component. Using revision and radiologic loosening as endpoints, the cumulative survival rate for the acetabular component was 86.3% at 10 years and 27.0% at 15 years. The survival of the femoral components was 81.3% at 15 years. Patients with avascular necrosis had a higher failure rate than patients with other diagnoses (P =.001). An area of cement mantle that was <2 mm thick affected adversely the survival rate of the acetabular components (P =.04).     

髋臼假体位置对人工股骨头应力分布的影响

目的探讨髋臼假体不同放置位置对髋关节置换术后人工股骨头压应力的生物力学影响。方法对8具尸体16侧髋关节标本按照全髋关节置换术髋臼的处理原则，制作16种人工髋臼放置的位置，共分成两组：髋臼向内侧位移组，从解剖位置起间隔2mm，递增至14mm，共8髋；靛臼向上方位移组，从解剖位置起间隔2mm，递增至14mm，共8髋。应用电阻应变片在生物力学试验机上测定各标本在轴向1000N载荷下人工股骨头的应变数据，记录人工股骨头所承受的压应力值。结果（1）髋臼向内侧位移组：髋臼假体位置每向内位移2mm，人工股骨头承受的压应力就增加，位移越多，股骨头承受的压应力增加就越明显，位移超过6mm后，压应力呈明显快速增加趋势；（2）髋臼向上方位移组：髋臼假体位置每向上位移2mm，除上移6mm应力值小于上移4mm外，人工股骨头承受的压应力总体趋势是增加，且上移超过8mm后，人工股骨头压应力值开始明显增加；（3）在相同位移情况下，向内位移时人工股骨头压应力明显大于向上位移。结论髋臼中心无论是向内或向上位移，股骨头承受的压应力均增加，且位移幅度越大，压应力增加越明显；向上位移6mm时，人工股骨头承受的应力值均小于前后位移点，未排除此位点是一应力缓冲点的可能。     

The precision and usefulness of preoperative planning for cemented and hybrid primary total hip arthroplasty

We evaluated the utility of a preoperative planning technique with a review of preoperative radiographs, templates, plans, charts and 6-week postoperative radiographs of 139 total hip arthroplasties (THAs) (116 cemented and 23 hybrid) to determine size, orientation of the implants, and cement column mantle, location of the planned and achieved center of rotation, and limb-length discrepancy. The acetabular component size was predicted exactly in 116 hips (83%) (within +/-1 size in 138 hips [99%]); the femoral component size was predicted exactly in 108 hips (78%) (within +/-1 size in 138 [99%]). In 75 arthroplasties (45%), the center of rotation was within 2 mm of horizontal and vertical distance from the plan, and in 127 (91%) arthroplasties, it was within 4 mm. The inclination of the cup averaged 44 degrees (range, 30 degrees -58 degrees ). The stem was in a neutral alignment in 122 hips (88%), varus in 11 hips (8%), and in 2 degrees of valgus in 6 hips (4%). In 103 arthroplasties with a normal contralateral hip or a THA, the average limb-length discrepancy was 1.71 mm. Preoperative planning is useful to predict the implant size, position, and alignment, to restore the center of rotation, and to equalize limb length.     

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.     

The utility and precision of analogue and digital preoperative planning for total hip arthroplasty

We prospectively compared the utility and precision of preoperative templating performed in printed films (analogue) with that performed on digital radiographs (digital) in 69 patients undergoing primary total hip replacement. Five patients were excluded when misplacement of the marker resulted in a magnification error greater that 10%; in the remaining patients (64 hips), the cup size was within +/- one size in 62 (97%) of the analogue and 52 (81%) of the digital (p=0.01) plans. The stem size was within +/- one size in 63 (98%) of the analogue and 60 (94%) of the digital (p=0.39) plans. The distance from the proximal corner of the lesser trochanter to the center of the prosthetic head (LTCD) in the analogue differed by 5 mm or more from the digital plan in nine cases (14%). Analogue preoperative planning yielded more predictable results than digital planning, particularly in terms of acetabular component size and LTCD that dictates limb lengthening-shortening. The sources of error were not clearly explained by variations in magnification. Inconsistent positioning of the magnification marker may jeopardise the safe implementation of digital templating.     

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.     

数字化模板测量在选择髋关节假体中的应用

目的 探讨采用数字化模板测量方法选择人工髋关节假体的应用效果.方法 选取2005年1月至2007年2月的122例患者(132髋),男68例,女54例;年龄35～82岁,平均62.4岁.应用医院数字化影像网络系统和数字化模板在计算机上进行全髋关节置换术前模板测量.由手术医生组和影像科医生组分别进行数字化模板测量,预测手术中所需假体型号的大小,并与手术中实际应用的假体型号进行比较.结果 手术医生组髋臼假体型号与股骨假体型号手术前后测量差异无统计学意义(Z=0.4531,P=0.6505;Z=0.5452,P=0.5856).手术医生组术前预测髋臼假体型号与股骨假体型号同术中应用的假体型号之间存在相关性(r=0.9361,P=0.0068;r=0.9435,P=0.0087).影像科医生组髋臼假体型号与股骨假体型号手术前后测量比较差异无统计学意义(Z=0.6834,P=0.4934;Z=0.1027,P=0.8990).影像科医生组术前预测髋臼假体型号、股骨假体型号同术中应用髋臼假体型号、股骨假体型号之间存在相关性(r=0.9214,P=0.0051;r=0.9357,P=0.0072).应用数字化模板测量选择的假体型号与术中实际应用假体型号相比较,髋臼假体的准确率达71.59%,股骨假体准确率达78.04%.结论 应用数字化模板测量进行术前设计,选择人工全髋关节置换的假体具有较高的准确率和可信度.     

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.