Anterior cortical line of femur and tibia is more accurate than mid-shaft line to determine knee extension angle relative to sagittal mechanical axis during total knee arthroplasty.

BACKGROUND: Accurate assessment of knee extension angle relative to sagittal mechanical axis (SMA) during TKA is usually obtained by computer navigation. Whether the lines along anterior cortex of distal femur and proximal tibia in short-knee imaging are accurate in determining knee extension angle has not been investigated. METHODS: A prospective study was conducted on 106 patients (116 knees) who underwent primary TKA. After complete anesthetization, the leg was elevated 30° and short-knee lateral fluoroscopy was performed. The angles between the anterior cortical line (ACL), and between the mid-shaft line (MSL) of the femur and tibia, were measured. After surgical exposure and bony registration into OrthoPilot navigation system, the leg was elevated again and degree of knee extension was recorded. The angles determined using three methods were compared. RESULTS: The mean extension angle observed by OrthoPilot (5.0° ± 6.8°, range -8°-25°) was not different from ACL method (5.3° ± 7.0°, range -8.1°-24.3°) (p = 0.811), but higher than MSL method (1.7° ± 7.1°, range -13.2°-18.1°) (p < 0.001). The mean absolute difference of ACL method from OrthoPilot was 0.2° ± 1.8° (range 0.0°-5.0°; 95%CI 0.0°-2.0°), and MSL method from OrthoPilot was 3.2° ± 2.6° (range 0.1°-8.2°; 95%CI 2.7°-3.7°). Measurement differences within 2° were found in 83.6% (97/116) and 37.9% (44/116) in the ACL and MSL method respectively (p < 0.001). CONCLUSION: ACL of femur and tibia in a short-knee imaging is more accurate than MSL for determining knee extension angle relative to SMA. ACL can be assessed intraoperatively as the anterior cutting surface of distal femur after bone cut during TKA and the palpable anterior tibial crest. This ACL measurement in a pre- or postoperative radiograph provides the minimal detectable change of 3.5° and helpful in clinical research that requires high precision measurement.

Digital Templating of THA Using PACS and an iPhone or iPad is as Accurate as Commercial Digital Templating Software.

BACKGROUND: Digital templating is a standard preoperative planning method in THA. Unfortunately, many hospitals cannot afford the software or have accessibility barriers owing to a limited number of installed computer workstations. We created a templating method using a picture archiving and communication system and the Keynote program on a mobile phone. The method's accuracy and reliability have not been compared with those of commercial digital templating software. QUESTIONS/PURPOSES: (1) How accurate is this novel method on iPhone and iPad mobile devices compared with a commercially available digital templating software program? (2) Is the method reproducible among users with different levels of experience? (3) Are the results similar for different types of femoral prostheses? METHODS: Between January 2017 and May 2020, we treated 209 patients for hip disease or trauma with primary cementless THA. We considered patients with a normal contralateral hip as potentially eligible for this retrospective study. Thus, 91% (191 of 209 hips) were eligible; a further 13% (27 hips) were excluded because of postoperative leg length discrepancy > 5 mm, femoral offset discrepancy > 5 mm (9% [18 hips]), intraoperative periprosthetic fracture (4% [eight hips]), and proximal femoral deformity (0.5% [one hip]), leaving 78% (164 hips) for analysis here. Their preoperative radiographs were evaluated by three independent assessors, including one senior orthopaedic surgeon, one senior resident, and one junior resident, using three methods. The first was digital templating using OrthoView software, which is a commercially available digital templating software program used worldwide and known to possess high accuracy. The other two methods were technically similar to one another, with the only difference being the interface: iPhone versus iPad. In both of those approaches, using the picture archiving and communication system measurement tool, we drew a circle on an acetabular radiograph to depict the cup. We took a photograph of the computer display and imported the photograph into slides of the Keynote program, a presentation software application for Mac computers, on both devices. It was then underlaid on transparent digital templates of the femoral stem, which were scanned from plastic templates and positioned at the center of each slide. We scaled the image to the template by adjusting the image size until a 15-cm straight line on the hip photograph was equal to the 15-cm scale markers of the template. All templating results were compared with the actual implanted cementless THA components to assess accuracy. All assessors were blinded to the information about the actual implants, and they were not involved in performing the surgical procedures. The intrarater and interrater reliabilities were analyzed using intraclass correlation coefficients and kappa values. The accuracy for predicting stem size for each type of the four stem designs was compared among the three methods. RESULTS: We were able to predict the acetabular cup size within one size in 92% of hips (151 of 164) using OrthoView and in 92% (150 of 164) using the novel method (p > 0.99). The accuracies of the three methods were comparable for predicting a femoral stem size within one size (OrthoView: 90% [148 hips], iPhone: 93% [152 hips], and iPad: 91% [149 hips]; p = 0.78), and neck length (OrthoView: 96% [157 hips], iPhone: 96% [158 hips], and iPad: 97% [159 hips]; p = 0.95). Using OrthoView, the neck offset was correctly predicted in 80% (132 hips), compared to 85% (139 hips) when using the iPhone and 82% (134 hips) when using the iPad (p = 0.57). All methods showed substantial or excellent agreement regarding intrarater and interrater reliability. There was no difference in accuracy regarding any of the four femoral stem designs we evaluated (Avenir, Excia, ML taper, and Metha). CONCLUSION: The digital templating technique for THA using an iPhone or iPad combined with a picture archiving and communication system demonstrated high accuracy, comparable to that of commercial digital templating software. This technique is reliable and reproducible for predicting a cementless prosthesis size, neck length, and offset in different types of femoral stems. It may be useful as an alternative in resource-constrained centers where commercial software programs are too expensive to be used in practice. LEVEL OF EVIDENCE: Level IV, diagnostic study.

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.

BACKGROUND: Preoperative 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. METHODS: A 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. RESULTS: The 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. CONCLUSION: Digital templating using PACS and iPhone is accurate and reproducible for predicting implant size of cementless THA.

Accuracy of intraoperative estimation of femoral stem anteversion in cementless total hip arthroplasty by using a digital protractor and a spirit level.

BACKGROUND: The femoral component anteversion during surgery is traditionally assessed by a visual assessment of the surgeon and has proven to be imprecise. We sought to determine the accuracy of a digital protractor and a spirit level to measure the stem anteversion during cementless THA. METHODS: A prospective study was conducted among 107 patients (114 hips) who underwent primary cementless THA via posterolateral approach. A pipe with a spirit level was attached to the tibial tubercle and intermalleolar midpoint. While the leg was held perpendicularly to the floor, stem anteversion was estimated by 3 methods: method A by visual assessment; method B by a digital protractor alone; and method C by a digital protractor combined with a spirit level. The angles were compared with the true anteversion measured by postoperative CT scan. RESULTS: The average anteversion by method C (22.8° ± 6.9°, range -2° to 40°) was significantly lower than method A (24.6° ± 5.2°, range 0° to 30°) (p=0.033), but not different from the true anteversion (22.1° ± 8.2°, range -5.4° to 43.1°) (p=0.445). There were no significant differences between method B (23.2° ± 8.2°, range -4° to 45°) and method A, C or the true anteversion. The mean deviation of the intraoperative estimation from the true anteversion was 0.8° ± 3.7° (range -7.1° to 8.0°) by method C; 1.2° ± 5.1° (range -8.8° to 14.3°) by method B; and 2.5° ± 7.4° (range -19.0° to 16.0°) by method A. Estimation error within 5° was found in 107 hips (93.9%) with method C; 86 hips (75.4%) with method B; and 59 hips (51.8%) with method A. CONCLUSION: Accurate estimation of stem anteversion during cementless THA can be determined intraoperatively by the use of a digital protractor and a spirit level. TRIAL REGISTRATION: Thai Clinical Trials Registry ( TCTR 20180326003 ). Registered on 20 March 2018. Retrospectively registered.

Smartphone-assisted technique in total hip arthroplasty can improve the precision of acetabular cup placement: a randomised controlled trial.

BACKGROUND: Malposition of the acetabular component mainly results from intraoperative pelvic motion and manual errors during cup placement. We investigated the outcomes of a device that uses a level indicator application of a smartphone to function as a pelvic tilt goniometer to assess intraoperative motion. The cup positions outside Lewinnek's safe zone were compared between the smartphone-assisted technique and the conventional method that uses a mechanical alignment guide. METHODS: A randomised controlled trial was conducted among 64 patients receiving primary cementless total hip arthroplasties (THAs) via a posterolateral approach from June 2015 to February 2017. Acetabular components were implanted either by conventional technique (n = 32) or using smartphone technique (n = 32). Inclination and anteversion angles were measured in supine pelvic radiographs. RESULTS: The inclination angle in the smartphone group was not significantly different from the conventional group (41.2° ± 3.9° vs. 40.3° ± 7.9°, p = 0.567). The anteversion angle was also similar (19.3 ± 3.8° vs 19.1° ± 5.9°, p = 0.856). However, the standard deviation of the angle in the smartphone group was significantly lower for inclination (p < 0.001) and anteversion (p = 0.016). There were 3 outliers (9.4%) in the smartphone group, but 13 (40.6%) in the conventional group (p = 0.008). The risk ratio was 0.23 (95% CI, 0.07-0.73). The risk difference was -0.31 (95% CI, -0.51- -0.11). CONCLUSION: The smartphone-assisted technique in THA improves the precision of cup placement and decreases the percentage of safe zone outliers.Thai Clinical Trials Registry (ID: TCTR20151123002).

Use of a Digital Protractor and a Spirit Level to Determine the Intraoperative Anteversion of Femoral Component during Cemented Hip Hemiarthroplasty: a Prospective Clinical Trial.

BACKGROUND: Femoral stem anteversion during hip arthroplasty is generally estimated by eye intraoperatively and has proven to be different from targeted values. This study aims to determine the accuracy of a novel technique using a digital protractor and a spirit level to improve surgeons' estimation of stem anteversion. METHODS: A prospective non-randomized study was conducted among 93 patients with femoral neck fracture who underwent cemented hemiarthroplasty via posterolateral approach. In the control group (N=62), five experienced surgeons assessed stem anteversion related to the posterior femoral condylar plane using visual estimation with a target angle of 15°-25°. In the study group (N=31), another two surgeons assessed stem anteversion with the same target angle by placing a digital protractor on the femoral stem inserter handle while the assistant held the leg in the truly vertical position, verified by a spirit level that was attached to the shin with cable ties. Stem anteversion was measured blind, postoperatively, on 2D-CT and compared with the intraoperative results. RESULTS: The mean postoperative anteversion was 22.4° (-4.2° to 51.3°, SD 11.1°) in the control group and 23.0° (16.0° to 29.9°, SD 3.6°) in the study group (P=0.810). The study group had more stems positioned in 15°-25° anteversion (71.0% vs 32.3%, P=0.001) and the mean absolute value of surgeon error was -0.2° (-5.4° to 7.0°, SD 3.0°). Twenty-eight stems of the study group (90.3%) had an error within 5°. Surgeon overestimation >5° was found in 1 hip (3.2%) and underestimation >5° was found in 2 hips (6.4%). CONCLUSION: Using a digital protractor and a spirit level was reliable with high accuracy and precision to improve the intraoperative estimation of cemented stem anteversion.

Use of smartphone to improve acetabular component positioning in total hip athroplasty: A comparative clinical study.

BACKGROUND: The position of the acetabular cup is important to the outcome of total hip athroplasty (THA). We devised an instrument that uses the level indicator application of smartphone together with a mechanical alignment guide to improve the precision of cup placement. This study aims to determine the percentage of acetabular cups positioned in the Lewinnek safe zone comparing between the conventional technique (using a mechanical alignment guide alone) and the smartphone technique (using a mechanical alignment guide combined with the devised instrument and smartphone). METHODS: A historical controlled trial was conducted among 82 patients who underwent primary THAs through a posterolateral approach. In the conventional group, 41 cups were placed during January 2013 and December 2014, whereas 41 cups in the smartphone group were placed during January 2015 and March 2016. Inclination and anteversion angles were measured in standardized pelvic radiographs. The cup orientation was compared between groups. RESULTS: The inclination angle in the smartphone group was significantly lower than in the conventional group (40.9° (SD 3.8) vs. 46.3° (SD 6.7), p < 0.001), but the anteversion angle was higher (19.6° (SD 4.4) vs. 16.5° (SD 6.1), p = 0.010). The smartphone group had more cups positioned in the Lewinnek safe zone (90.2% vs. 56.1%, p = 0.001) and longer operative times (136 (SD 27) vs. 119 (SD 23) min, p = 0.011). No significant difference was found for blood loss ( p== 0.384) or dislocation rate ( p = 0.494). CONCLUSION: Using the computerized function of smartphone could improve the precision of cup positioning. Most cups were placed within a narrow margin inside the Lewinnek safe zone.

Erratum: Missing Sentence and Word.

[This corrects the article on p. 54 in vol. 7.].

Bilateral Femoral Neck Fractures in Cerebrotendinous Xanthomatosis Treated by Hip Arthroplasties: The First Case Report and Literature Review.

INTRODUCTION: Cerebrotendinous xanthomatosis (CTX) is a rare autosomal recessive lipid storage disease caused by mutations of the CYP27A1 gene and deficiency of the sterol-27-hydroxylase enzyme in bile acid biosynthesis. It is characterized by the accumulation of cholestanol and bile alcohols in plasma, the formation of xanthomatous lesions in various tissues, and organ degeneration. This disorder is also associated with osteoporosis and increased risk of fracture. To date, only two CTX patients with femoral neck fractures have been reported. Neither was treated by arthroplasties, and the operative outcomes are lacking. CASE REPORT: We report the case of a 46-year-old Thai female who presented with consecutive bilateral femoral neck fractures following minor trauma within a 3-year period and received cementless bipolar hemiarthroplasties. Her phenotypic expression included Achilles tendon masses, childhood-onset cataracts, intellectual disability, and cerebellar ataxia. A brain computed tomography showed non-enhancing hypodense lesions in the bilateral cerebellar hemispheres with mild brain atrophy. Histopathology from an Achilles tendon biopsy revealed tendinous xanthoma and molecular analysis confirmed a homozygous nonsense mutation, c.1072C>T (p.Gln358Ter), in exon 6 of the CYP27A1 gene. The intra-operative crack of a calcar femorale was a major complication during both prosthetic insertion surgeries and warranted cerclage wiring. At the 7-month follow-up of the right hip and the 41-month follow-up of the left hip, postoperative radiographs showed well-fixed and well-aligned prostheses. Independent household ambulation could be resumed with Harris hip scores of 81 points equally. CONCLUSION: CTX is associated with osteoporosis, and middle-aged patients could present with femoral neck fracture following minor trauma. Cementless bipolar hemiarthroplasty for a totally displaced fracture is justified for a patient who has cognitive impairment. Intra-operative fracture is a major complication during prosthetic insertion and warrants cerclage wiring to achieve predictable bone healing and a satisfactory result.

Use of drop and dangle rehabilitation protocol to increase knee flexion following total knee arthroplasty: a comparison with continuous passive motion machine.

BACKGROUND: There are variations in the type of rehabilitation program and duration of using the continuous passive motion (CPM) machine to increase range of motion (ROM) following total knee arthroplasty (TKA). OBJECTIVE: To compare the outcomes of the 'drop and dangle' (D&D) protocol vs. a 3-hour daily CPM for the purpose of increasing flexion following TKA. MATERIAL AND METHOD: A prospective non-concurrent controlled intervention study was conducted on patients who underwent primary TKA atLampang Hospital from December 2009 to August 2011 (D&D group, n = 36) andfrom September 2011 to December 2012 (CPM group, n = 33). The same surgeon using the same prosthesis design performed all surgeries. The legs in D&D group were placed into the knee immobilizer at 70 flexion and removed on postoperative day 1 (POD1). The passive ROM exercise was then started by dropping the affected leg over the bedside, and gently flexing and bending the knee with the help of the unaffected leg to achieve maximal flexion. The legs in the CPM group were immobilized with a Jones bandage in full extension for 24 hours, and then placed into CPM machine for three, 1-hour per day sessions. The clinical data were statistically compared between the two groups. RESULTS: Patient baseline characteristics in both groups were not different. The D&D group had more average passive flexion in POD1 (67.0° ± 14.2° vs. 59.1° ± 3.2°, p < 0.001) and POD2 (76.6° ± 14.2° vs. 69.8° ± 13.3° , p = 0.008). Higher rates of flexion were observed in PODs 3-7 but they were not significant. Flexion at discharge in the D&D group was 100.6° ± 6.8° and 96.4°+10.2° in the CPM group (p = 0.005). At 6 weeks, rates of flexion in both groups were similar (D&D 99.8° ±10.4°, CPM 103.9° ± 10.4°, p = 0.138). Rates offlexion were also similar at 1 year (D&D 112.0° ± 10.4°, CPM 111.6° ± 12.6°, p = 0.892). CONCLUSION: D&D protocol provided more passive knee flexion than the use of CPM in the first two days after TKA and at discharge. These differences were not significant at 6 weeks and 1 year

Invention technique and clinical results of Lampang cement injection gun used in hip hemiarthroplasty.

BACKGROUND: Cemented hemiarthroplasty is the common treatment of femoral neck fracture in elderly patients. The authors had invented Lampang cement gun (LCG) from a caulking gun to improve cementing technique. There was no previous study about LCG in clinical use. OBJECTIVE: To describe invention technique and evaluate clinical result of using LCG for cemented hemiarthroplasty in elderly patients with femoral neck fracture. MATERIAL AND METHOD: A retrospective study was conducted on 96 elderly patients who underwent cemented hemiarthroplasty (58 Austin Moore, 14 Thompson, 24 bipolar) in Lampang Hospital between October 2003 and April 2008. The femoral canal was filled with cement by using LCG Clinical outcome was assessed by Harris hip score (HHS). Radiographic quality of cementing technique was evaluated by Barrack's grading system. RESULTS: The mean age of the patients was 76 years (range, 62-96) and follow-up period was 39 months (range, 12-66). Twenty-four patients died and five were lost to follow-up. The mean HHS in bipolar group was higher than Thompson and Austin Moore groups (83.2, 78.3 and 76.9 respectively). Excellent and good scores were found in 90.9% of bipolar hips compared with 46.7% in unipolar hips. Less than 10% of the patients had poor clinical result. Cement mantles was grade A 37.3%, B 32.8%, C 20.9% and D 9%. Probably loose was found in one grade-D hip. Two grade-D hips were removed due to infection and dislocation. One grade-C hip was revised due to periprosthetic fracture. The mortality rate at 36 months was 20.8% in unipolar and 8.3% in bipolar group. CONCLUSION: The use of LCG for cemented hemiarthroplasties in elderly patients with femoral neck fracture provided satisfactory clinical outcome. LCG could be used to improve cementing technique and save the operative cost.

Comparison of caulking gun and standard cement gun using for femoral cementation.

BACKGROUND: Currently the standard femoral cementing technique requires cement injection gun to deliver bone cement into the femoral canal. The standard cement gun is expensive and must be imported. There is no previous study about the use of a household caulking gun for femoral cementation. OBJECTIVE: To compare the radiographic quality of cementing technique in proximal femur between using standard cement gun and caulking gun. MATERIAL AND METHOD: Experimental study was performed on ten pairs of adult bovine femora. After the proximal femoral canal was prepared for cementation, each pair of bovine femora was randomly selected to be injected with bone cement with a standard cement gun in one side. The other side was injected with a caulking gun and the authors' invented kit. The prosthesis was inserted and radiographs were taken. Radiographic quality of cement interdigitation was evaluated by the modified Barrack's cement grading score. Cement distribution was categorized into 14 zones of Gruen. The data was statistically analyzed by Wilcoxon matched pairs signed-rank test. The inter-observer and intra-observer agreement was analyzed by Kappa analysis. RESULTS: Radiographic quality score of femoral cementation in the group using the caulking gun was not statistically different from in the group using the standard gun in all 14 Gruen zones (p > 0.05). Intra-observer and inter-observer agreement were moderate (Kappa = 0.71 and 0.59 respectively). CONCLUSION: The radiographic quality of femoral cementation using the caulking gun was not significantly different from the standard cement gun. The caulking gun and invented kit could be applied in clinical use and save the operative cost.