Digital templating in total knee and hip replacement: an analysis of planning accuracy

Purpose

The aim of this study was to determine how well pre-operative size selection for total knee and hip arthroplasties based on the digital imaging with and without additional referencing correlated with the size actually implanted.

Methods

Size selection planning of total knee arthroplasty by digital templating was documented in 46 cases with reference ball (group A) and in 48 cases without ball (group B). In addition, prospective analysis of pre-operative planning was conducted for 52 acetabular components with reference ball (group C) and 69 without ball (group D) as well as stem planning in 38 cases with ball (group E) and 54 cases without ball (group F). The data were analysed and compared with the size of the final component selected during surgery.

Results

The correlation between planned and implanted size for total knee arthroplasty in group A resulted in femoral anteroposterior (AP) r = 0.8622 and lateral r = 0.8333 and in group B AP r = 0.4552 and lateral r = 0.6950. Tibial in group A was AP r = 0.9030 and lateral r = 0.9074 and in group B AP r = 0.7000 and lateral r = 0.6376. For the acetabular components, the results in group C were r = 0.5998 and group D r = 0.6923. For stems, group E was r = 0.5306 and group F r = 0.5786. No correlation between BMI and the difference between planned and implanted size was found in any of the groups.

Conclusion

In the case of total hip arthroplasty there was a relatively low correlation between planned and implanted sizes with or without reference ball. For total knee arthroplasties the already high precision of size planning was further improved by the additional referencing with a reference ball.     

Fluoroscopic Templating Technique for Precision Arthroscopic Rim Trimming

Arthroscopic rim trimming for femoroacetabular impingement can be technically challenging to perform with precision. Intraoperative assessment of the extent of acetabular rim resection is very important. Over-resection can lead to hip instability and even iatrogenic dislocation. Under-resection may leave residual impingement. A novel imaging technique is presented that is simple, practical, and readily available. The technique involves matching the fluoroscopic C-arm image intensifier to the operative pelvis while under the desired amount of hip distraction so that a horizontal anteroposterior hip image appears on the viewing monitor. An erasable marking pen is used to draw the desired area of planned acetabular rim resection directly on the viewing monitor screen. Intermittent fluoroscopic images with the raised stationary C-arm device allow assessment of superior (lateral) and anterior rim resection. The surgeon “wipes away” the drawn template with the radiopaque metallic bur until the all-important medial template border is reached, indicating that the actual rim resection matches that intended in a controlled and precise manner.     

Surgical planning of total hip arthroplasty: accuracy of computer-assisted EndoMap software in predicting component size

Purpose The purpose of our study was to assess the accuracy of a computer-assisted templating in the surgical planning of patients undergoing total hip arthroplasty utilizing EndoMap software (Siemans AG, Medical Solutions, Erlangen, Germany). Endomap Software is an electronic program that uses DICOM images to analyze standard anteroposterior radiographs for determination of optimal prosthesis component size.Methods We retrospectively reviewed the preoperative radiographs of 36 patients undergoing uncomplicated primary total hip arthroplasty, utilizing EndoMap software, Version VA20. DICOM anteroposterior radiographs were analyzed using standard manufacturer supplied electronic templates to determine acetabular and femoral component sizes. No additional clinical information was reviewed. Acetabular and femoral component sizes were assessed by an orthopedic surgeon and two radiologists. Mean and estimated component size was compared with component size as documented in operative reports.Results The mean estimated acetabular component size was 53 mm (range 48–60 mm), 1 mm larger than the mean implanted size of 52 mm (range 48–62 mm). Thirty-one of 36 acetabular component sizes (86%) were accurate within one size. The mean calculated femoral component size was 4 (range 2–7), 1 size smaller than the actual mean component size of 5 (range 2–9). Twenty-six of 36 femoral component sizes (72%) were accurate within one size, and accurate within two sizes in all but four cases (94%).Conclusion EndoMap Software predicted femoral component size well, with 72% within one component size of that used, and 94% within two sizes. Acetabular component size was predicted slightly better with 86% within one component size and 94% within two component sizes.     

人工智能辅助手术规划系统在个体化全髋关节假体精准植入中的应用

目的 与传统二维胶片模板测量术前计划比较,探讨人工应用智能辅助三维数字化手术规划系统在个体化全髋关节置换术（total hip arthroplasty,THA）假体植入中应用的准确性。方法 回顾性分析88例行单侧THA手术病人的临床资料,其中传统模板组（44例）,人工智能组（44例）,记录比较两组在假体型号大小选择、植入位置、患侧偏心距、双下肢等长重建等方面的差异。结果 人工智能组髋臼杯和股骨柄假体型号的预测吻合率分别为95.5%、88.6%,均高于传统模板组的75.0%、65.9%,差异有统计学意义（P＜0.05）。人工智能组手术后偏心距和肢体长度的差值分别为（4.73±2.97） mm、（3.42±2.32） mm,均较传统模板组更小,差异有统计学意义（P＜0.05）。结论 人工智能辅助手术规划系统对人工髋关节假体型号的预测、患侧肢体偏心距的恢复、双下肢等长重建更加精准。     

Digital templating in hip hemiarthroplasty: Is it possible to accurately predict femoral head size from magnification alone?

BackgroundTemplating is an integral part of pre-operative planning in elective hip arthroplasty to achieve favourable long-term outcomes, but its applications in trauma surgery remain limited. When templating from radiographs without a calibration marker, there is always an element of magnification which must be accounted for. Our aim was to establish our institute-specific magnification and to determine whether using this to predict femoral head size in hemiarthroplasty was more accurate than using set magnifications previously reported in the literature.Materials & methodsFifty consecutive patients who underwent hip hemiarthroplasty were retrospectively identified, their pre-operative radiographs reviewed and femoral head measured with templating software. Intra- and inter-observer reliability analyses were performed. Using this value, and two set values of 15% and 21% magnification, we attempted to predict femoral head sizes of our original cohort. The results were compared using paired t-test to ascertain if there was any significant difference in accuracy.ResultsWe established our institute-specific magnification as 17%. Inter- and intra-observer reliability were excellent. However, using this magnification we were only able to correctly predict to within ± one femoral head size in 49% of patients. There was no significant difference in accuracy comparing our institute-specific magnification with other magnifications from the literature.ConclusionWe would not recommend using magnification factor in digital templating software as this could potentially lead to errors in predicting final femoral head size in hip hemiarthroplasty and adversely affect patient outcomes.     

The influence of computed tomography preoperative planning on clinical outcomes after anatomic total shoulder arthroplasty: a matched cohort analysis

BackgroundEvaluation, characterization, and correction of glenoid deformity are an important part of performing anatomic total shoulder arthroplasty (TSA). Three-dimensional computed tomography (3D CT) planning has been shown to improve implant position, but the impact on clinical outcomes is less clear. The purpose of the current study is to compare clinical outcomes of TSA performed with 3D CT preoperative planning with matched controls performed without CT-based planning.MethodsUtilizing a multicenter shoulder arthroplasty registry, patients who underwent a TSA with 2-year clinical follow-up were retrospectively identified. These patients were divided into two cohorts based on technique for glenoid guide pin placement based on surgeon preference: 1) those who utilized 3D preoperative templating with or without patient-specific instrumentation (PSI) and 2) a control group of TSAs performed without 3D CT preoperative planning. The two groups were matched 1:1 based on age, sex, and baseline American Shoulder and Elbow Surgeons (ASES) score. Patient-reported outcomes and active range of motion (ROM) obtained at 2 years postoperatively were assessed and compared between the two cohorts. A subgroup analysis was also performed comparing outcomes in patients with 3D CT preoperative planning with and without PSI.ResultsData collection was performed on 84 study patients with 3D CT preoperative planning (51 with PSI and 33 without) and 84 matched control patients without CT-based planning (168 patients in total). Baseline characteristics were similar between the groups. Improvement from baseline for the ASES score (study group: 45.4, controls: 39.0, P = .029) and external rotation at 90^° of abduction (study group: 42^° vs. 29^°, P = .009) was significantly greater in the CT-based planning group than that in matched controls. There were no other significant differences in improvement in outcomes or ROM between the two groups. Within the 3D CT cohort, there were no significant differences in patient-reported outcomes or ROM between TSAs performed with or without PSI. A significantly greater percentage of patients with 3D CT planning achieved a patient acceptable symptomatic state than controls (89% vs. 75%, P = .016).ConclusionTSAs performed with 3D CT preoperative glenoid planning with or without utilization of PSI were associated with statistically significantly greater improvement from baseline in ASES scores and external rotation at 90^° of abduction than TSA performed without 3D CT planning. The clinical significance of this finding is unclear, as the differences failed to meet a clinically significant threshold.     

数字化模板与传统胶片模板术前测量在髋假体精确性选择上的比较研究

目的探讨数字化模板与传统胶片模板测量在髋关节置换术中的精确性差别及数字化术前模板测量的应用价值。方法分别应用数字化模板与传统胶片模板对2005年1月至2006年6月间行非骨水泥型人工髋关节假体置换的患者进行数字化术前计划。其中男23例，女17例，年龄（50．1±12．9）岁。比较计划与手术实际间假体尺寸、置放位置、偏心距及下肢长度的吻合程度。结果两种方法在假体型号（包括臼杯、股骨柄、颈长）选择方面与术中实际尺寸吻合度存在差异（P〈0．05），数字化模板测量与术中实际吻合度更高。对偏心距的设定，与术中实际一致者，数字化模板测量达14例（占70％），优于传统测量（8例，占40％）。应用配对t检验对术前计划及术中实际的截骨高度进行统计学分析，显示传统模板设定值较术中实际相差（0．61±0．21）cm，差异具有统计学意义（P〈0．05），数字化模板者相差（0．01±0．15）cm，吻合度高。结论数字化术前模板测量可提高术中假体选择的精确性，并能更好地完成截骨高度的术前制定，从而恢复患肢的长度及偏心距。     

The stability of nonporous and macroporous titania thin films in aqueous electrolyte solutions

A simple electrochemical approach was used to evaluate the stability and porosity of titania and silica thin films spin coated on electrode surfaces. This approach involved monitoring the magnitude of the Faradaic current of diffusing redox probes at the modified electrode surfaces over the course of a week to 4.5 months. Relatively nonporous films were examined as well as films templated with polystyrene latex spheres. The results show that templated titania films were significantly more porous compared to non-templated films. After the defect sites in the templated films were blocked, their long-term stability in aqueous electrolyte was evaluated. For titania, blocking was done by spin coating a dilute titania sol on the top of the film whereas for silica, the film was soaked in octyltrimethoxysilane. Both types of titania films (templated and non-templated) were found to be significantly more stable than the corresponding silica films, showing no signs of deterioration in simple electrolyte solutions during the entire evaluation period. In contrast, silica films showed significant deterioration in as little as 3 days. The enhanced stability of the titania films relative to silica films in near neutral electrolyte solutions was attributed to the differences in the point of zero charge of the oxide films.     

初次全髋关节置换术前胶片模板测量与评估

目的：通过胶片模板测量进行全髋关节置换术前计划、术后重复测量评估探讨胶片模板测量在全髋关节置换术前计划中的准确性和重要性。方法：2012年3月至2012年8月,收集我科同一位高年资医师行全髋关节置换病例72例（84髋）作研究对象。术前通过胶片模板测量,决定股骨颈截骨位置,计划髋臼、股骨柄、股骨头假体型号以及植入位置,调整双下肢长度;术后通过重复测量对术前计划进行评估和验证。结果：所有病例股骨颈截骨位置与术前计划相差均在5mm范围内,其中相差小于3mm者占84．5％。术前肢体平均短缩10mm（0～35mm）,术后肢体平均短缩3mm（0-11mm）,差异有统计学意义;术后双下肢长度相差在5mm以内者占90．5％。术前模板测量出的假体型号与实际应用的假体比较,髋臼假体完全符合率65．4％、相差1个型号以内的符合率为94．0％;股骨假体完全符合率为83．3％、相差1个型号以内的符合率为96．4％;股骨头假体完全符合率为63．1％、相差1个型号以内的符合率为98．8％。结论：全髋关节置换术前胶片模板测量对于术中假体型号选择具有较好的预测作用,对于假体位置安放以及双下肢长度调整均具有重要意义。     

The role of pre-operative templating in primary total knee replacement

Templating of preoperative X-rays is routinely performed before a total knee replacement. We performed this retrospective study on preoperative templating in primary total knee replacement to assess its accuracy and reproducibility. Preoperative radiographs of 47 patients were templated twice by two observers separately after a gap of 3 months. The size of actual implant used was compared to the size predicted by templating. Data were analysed to assess inter and intra-observer variation. Templating was accurate for both tibial and femoral components in only 53.2% of observations. This study also revealed that templating is a highly-subjective and observer-dependent technique. Inter-observer and intra-observer mismatch was present in 46.8% and 43.6% of readings respectively. We conclude from this study that preoperative templating is neither accurate nor reproducible.