Accuracy of cup placement in total hip arthroplasty by means of a mechanical positioning device: a comprehensive cadaveric 3d analysis of 16 specimens

Introduction: We tested whether a mechanical device (such as Hipsecure) to pinpoint the anterior pelvic plane (APP) as a guide can improve acetabular cup placement. To assess accuracy we asked: (1) is the APP an effective guide to position acetabular cup placement within acceptable ° of divergence from the optimal 40° inclination and 15° anteversion; (2) could a mechanical device increase the number of acetabular cup placements within Lewinnek’s safe zone (i.e. inclination 30° to 50°; anteversion 5° to 25°)? Methods: 16 cadaveric specimens were used to assess the 3D surgical success of using a mechanical device APP to guide acetabular cup placement along the APP. We used the Hipsecure mechanical device to implant acetabular cups at 40° inclination and 15° anteversion. Subequently, all cadaveric specimens with implants were scanned with a CT and 3D models were created of the pelvis and acetabular cups to assess the outcome in terms of Lewinnek’s safe zones. Results: The mean inclination of the 16 implants was 40.6° (95% CI, 37.7–43.4) and the mean anteversion angle was 13.4° (95% CI, 10.7–16.1). All 16 cup placements were within Lewinnek’s safe zone for inclination (between 30° and 50°) and all but 2 were within Lewinnek’s safe zone for anteversion (between 5° and 25°). Conclusion: In cadaveric specimens, the use of a mechanical device and the APP as a guide for acetabular cup placement resulted in good positioning with respect to both of Lewinnek’s safe zones.

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Three-dimensional analysis of tooth movement after intrusion of a supraerupted molar using a mini-implant with partial-fixed orthodontic appliances

The Angle Orthodontist ◽

10.2319/060912-480.1 ◽

2012 ◽

Vol 83 (2) ◽

pp. 274-279 ◽

Cited By ~ 6

Author(s):

Shin-Jae Lee ◽

Sook-Yun Jang ◽

Youn-Sic Chun ◽

Won Hee Lim

Keyword(s):

Tooth Movement ◽

Treatment Time ◽

Three Dimensional ◽

3D Models ◽

Orthodontic Appliances ◽

Scanning System ◽

3D Analysis ◽

Fixed Orthodontic Appliances ◽

The Mean ◽

3D Software

ABSTRACT Objective: To evaluate three-dimensional (3D) positional changes of an intruded tooth, a neighboring tooth, and a tooth connected to a mini-implant following intrusion of a single supraerupted molar, using a mini-implant with partial-fixed orthodontic appliances. Materials and Methods: The study consisted of 14 adult patients (two males and 12 females, mean age 41.9 years) with a supraerupted molar due to loss of an antagonist. Intrusion was performed using a mini-implant with a partial strap-up. The mean treatment time was 11.9 months, and the mean retention time was 23.3 months. To quantify the positional changes of the teeth, 3D models using a laser-based, dental scanning system and 3D software at pretreatment, posttreatment, and retention were oriented in a coordinate system and superimposed using nonmoved teeth as references. The changes on the x-, y-, and z-axes were measured at the tip of each cusp in the involved teeth. Results: A supraerupted molar was intruded by a mean amount of 1.35 ± 0.48 mm and was well maintained during the retention period. The overall change in the neighboring tooth was insignificant, although it showed opposite movement compared to the intruded tooth during the intrusion. The tooth connected to a mini-implant exhibited a secure anchorage. Conclusion: 3D analysis showed the detailed positional changes of each tooth, and the involved molars were well maintained after intrusion.

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Highly crosslinked polyethylene wear rates and acetabular component orientation

The Bone & Joint Journal ◽

10.1302/0301-620x.100b7.bjj-2017-1457.r3 ◽

2018 ◽

Vol 100-B (7) ◽

pp. 891-897 ◽

Cited By ~ 12

Author(s):

M. G. Teeter ◽

B. A. Lanting ◽

D. D. Naudie ◽

R. W. McCalden ◽

J. L. Howard ◽

...

Keyword(s):

Wear Rate ◽

Acetabular Component ◽

Inclination Angle ◽

Polyethylene Wear ◽

Safe Zone ◽

Anteversion Angle ◽

Median Difference ◽

Head Penetration ◽

The Mean ◽

Acetabular Components

Aims The aim of this study was to determine whether there is a difference in the rate of wear between acetabular components positioned within and outside the ‘safe zones’ of anteversion and inclination angle. Patients and Methods We reviewed 100 hips in 94 patients who had undergone primary total hip arthroplasty (THA) at least ten years previously. Patients all had the same type of acetabular component with a bearing couple which consisted of a 28 mm cobalt-chromium head on a highly crosslinked polyethylene (HXLPE) liner. A supine radiostereometric analysis (RSA) examination was carried out which acquired anteroposterior (AP) and lateral paired images. Acetabular component anteversion and inclination angles were measured as well as total femoral head penetration, which was divided by the length of implantation to determine the rate of polyethylene wear. Results The mean anteversion angle was 19.4° (-15.2° to 48°, sd 11.4°), the mean inclination angle 43.4° (27.3° to 60.5°, sd 6.6°), and the mean wear rate 0.055 mm/year (sd 0.060). Exactly half of the hips were positioned inside the ‘safe zone’. There was no difference (median difference, 0.012 mm/year; p = 0.091) in the rate of wear between acetabular components located within or outside the ‘safe zone’. When compared to acetabular components located inside the ‘safe zone’, the wear rate was no different for acetabular components that only achieved the target anteversion angle (median difference, 0.012 mm/year; p = 0.138), target inclination angle (median difference, 0.013 mm/year; p = 0.354), or neither target (median difference, 0.012 mm/year; p = 0.322). Conclusion Placing the acetabular component within or outside the ‘safe zone’ did not alter the wear rate of HXLPE at long-term follow-up to a level that risked osteolysis. HXLPE appears to be a forgiving bearing material in terms of articular surface wear, but care must still be taken to position the acetabular component correctly so that the implant is stable. Cite this article: Bone Joint J 2018;100-B:891-7.

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The Difference of Acetabular Cup Orientation Between Two Surgical Sides After Primary Total Hip Arthroplasty by Right-handed Surgeons

10.21203/rs.3.rs-192946/v1 ◽

2021 ◽

Author(s):

Ao Xiong ◽

su liu ◽

Guoqing Li ◽

Jian Weng ◽

Deli Wang ◽

...

Keyword(s):

Total Hip Arthroplasty ◽

Hip Arthroplasty ◽

Safe Zone ◽

Dominant Hand ◽

Acetabular Cup ◽

Total Hip ◽

Left And Right ◽

The Mean ◽

The Right ◽

Primary Total Hip Arthroplasty

Abstract Background: We performed the retrospective cohort study to compare the acetabular cup orientation, including anteversion angle (AA) and inclination angle (IA), of dominant hand side and non-dominant hand side after primary total hip arthroplasty (THA) by right-handed orthopedic surgeons. Methods: Between January 2018 and December 2018, 290 patients who aged below 60 years and underwent primary THA were retrospective screened. Patients who had hemiarthroplasty, previous hip surgery, ankylosing spondylitis, developmental dysplasia of hip (DDH, Crowe type-Ⅲ and type-Ⅳ), severe comorbidity, missing information, inferior quality radiographs were excluded. According to the surgery side, all patients were divided into left group and right group. Postoperative plain radiographs were analyzed to compare the AA and IA between left and right side. Univariate and stepwise multivariable linear regression to control included confounding factors. Stratified analysis was performed to identify whether the operation approach can affect the result, including anterolateral (ALA) and posterolateral approach (PLA). Results: The mean AA was 17.7° (range 6.0° to 30.0°) and 21.0° (range 9.5° to 35.0°) for the left and right side respectively. The mean difference was 3.28° (95% CI: 1.92 – 4.64; P<0.001). The mean IA was 41.1° (range 24.0° to 59.0°) and 40.1° (range 20.5° to 56.0°) for the left and right side respectively (P=0.314). 113 patients' AA within the “safe zone” in the left (93.4 %), while the right was 93 patients (82.3 %) (P=0.009). 95 patients' IA within the “safe zone” in the left (78.5 %), while the right was 97 patients (85.8 %) (P=0.144). The IA of ALA group was smaller than PLA group in both sides. The mean difference was 3.98° (95% CI: 1.22 - 6.74; P=0.005). Conclusions: We concluded that AA in left side may be more accurate than right side after primary THA by right-handed surgeons. The IA was no difference between the two sides, while it was smaller in ALA than in PLA. The results are still needed to be verified in future.

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Dislocation Rates following Anterior Approach THA: The Role of Functional Pelvic Tilt

The Journal of Hip Surgery ◽

10.1055/s-0038-1635101 ◽

2017 ◽

Vol 01 (04) ◽

pp. 194-199

Author(s):

Colin McNamara ◽

Eric Slotkin ◽

Amar Mutnal ◽

Wael Barsoum ◽

Juan Suarez ◽

...

Keyword(s):

Anterior Approach ◽

Pelvic Tilt ◽

Reference Frames ◽

Safe Zone ◽

Dislocation Rate ◽

Abduction Angle ◽

Acetabular Cup ◽

Level Of Evidence ◽

Zone Parameters ◽

The Mean

AbstractVarious target zones for acetabular cup placement have been suggested to minimize dislocation following total hip arthroplasty (THA), though dislocations occur despite proper positioning. The authors have reported accuracy of fluoroscopic guidance in cup positioning during direct anterior approach (DAA) THA when using a standardized fluoroscopic technique functional pelvic tilt. They believe that cup placement with regard to functional pelvic tilt, rather than static reference frames, will offer improved stability. A cohort of 1,597 fluoroscopy-assisted DAA primary unilateral THA patients was prospectively followed for a minimum of 1 year and component position measured radiographically. Target cup position was based off the standing anteroposterior pelvis while using conventional safe zone parameters. Dislocation rate was assessed. Average follow-up was 13.1 months (range 1–6 years). The mean abduction angle was 37.7° and the mean anteversion angle was 16.2°. Overall, 1,517 (95.0%) fell within the targeted abduction range, 1,528 (95.7%) fell within the targeted anteversion range, and 1,456 (91.2%) simultaneously met both criteria. There were nine dislocations, eight within the combined safe zone, for a dislocation rate of 0.56%. Fluoroscopy can improve accuracy and precision of cup placement in DAA THA. Conventional safe zone parameters applied using functional pelvic tilt resulted in a low dislocation rate, with most dislocations occurring within the safe zone. Using a dynamic functional safe zone may further reduce dislocation rates after DAA THA, though other factors that contribute to instability must be accounted for in future studies. This study had a III level of evidence.

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Quality Control in 3D Printing: Accuracy Analysis of 3D-Printed Models of Patient-Specific Anatomy

Materials ◽

10.3390/ma14041021 ◽

2021 ◽

Vol 14 (4) ◽

pp. 1021

Author(s):

Bernhard Dorweiler ◽

Pia Elisabeth Baqué ◽

Rayan Chaban ◽

Ahmed Ghazy ◽

Oroa Salem

Keyword(s):

Wall Thickness ◽

Large Scale ◽

Fused Deposition Modeling ◽

Vascular Anatomy ◽

3D Models ◽

Patient Specific ◽

Stl File ◽

Fused Deposition ◽

3D Printed ◽

The Mean

As comparative data on the precision of 3D-printed anatomical models are sparse, the aim of this study was to evaluate the accuracy of 3D-printed models of vascular anatomy generated by two commonly used printing technologies. Thirty-five 3D models of large (aortic, wall thickness of 2 mm, n = 30) and small (coronary, wall thickness of 1.25 mm, n = 5) vessels printed with fused deposition modeling (FDM) (rigid, n = 20) and PolyJet (flexible, n = 15) technology were subjected to high-resolution CT scans. From the resulting DICOM (Digital Imaging and Communications in Medicine) dataset, an STL file was generated and wall thickness as well as surface congruency were compared with the original STL file using dedicated 3D engineering software. The mean wall thickness for the large-scale aortic models was 2.11 µm (+5%), and 1.26 µm (+0.8%) for the coronary models, resulting in an overall mean wall thickness of +5% for all 35 3D models when compared to the original STL file. The mean surface deviation was found to be +120 µm for all models, with +100 µm for the aortic and +180 µm for the coronary 3D models, respectively. Both printing technologies were found to conform with the currently set standards of accuracy (<1 mm), demonstrating that accurate 3D models of large and small vessel anatomy can be generated by both FDM and PolyJet printing technology using rigid and flexible polymers.

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Digital 3D models of theropods for approaching body-mass distribution and volume

Journal of Iberian Geology ◽

10.1007/s41513-021-00172-1 ◽

2021 ◽

Author(s):

Matías Reolid ◽

Francisco J. Cardenal ◽

Jesús Reolid

Keyword(s):

Body Length ◽

Heat Dissipation ◽

Volume Ratio ◽

3D Models ◽

The Body ◽

3D Analysis ◽

Skull Length ◽

Knowing That ◽

Fossil Bones ◽

Primitive Forms

AbstractThe aim of this work is to obtain diverse morphometric data from digitized 3D models of scientifically accurate palaeoreconstructions of theropods from eight representative families. The analysed polyvinyl chloride (PVC) models belong to the genera Coelophysis, Dilophosaurus, Ceratosaurus, Allosaurus, Baryonyx, Carnotaurus, Giganotosaurus, and Tyrannosaurus. The scanned 3D models were scaled considering different body-size estimations of the literature. The 3D analysis of these genera provides information on the skull length and body length that allows for recognition of major evolutionary trends. The skull length/body length in the studied genera increases according with the size of the body from the smallest Coelophysis with a ratio of 0.093 to ratios of 0.119–0.120 for Tyrannosaurus and Giganotosaurus, the largest study theropods. The study of photogrammetric 3D models also provides morphometric information that cannot be obtained from the study of bones alone, but knowing that all reconstructions begin from the fossil bones, such as the surface/volume ratio (S/V). For the studied theropod genera surface/volume ratio ranges from 35.21 for Coelophysis to 5.55 for Tyrannosaurus. This parameter, closely related to the heat dissipation, help in the characterization of the metabolism of extinct taxa. Accordingly, slender primitive forms of the Early Jurassic (i.e. Coelophysis and Dilophosaurus) had relatively smaller skulls and higher mass-specific metabolic rates than the robust large theropods of the Cretaceous (i.e. Giganotosaurus and Tyrannosaurus). This work presents a technique that, when applied to proper dinosaur models, provides extent and accurate data that may help in diverse study areas within the dinosaur palaeontology and palaeobiology.

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Investigating the Use of Natural and Artificial Records for Prediction of Seismic Response of Regular and Irregular RC Bridges Considering Displacement Directions

Applied Sciences ◽

10.3390/app11030906 ◽

2021 ◽

Vol 11 (3) ◽

pp. 906

Author(s):

Payam Tehrani ◽

Denis Mitchell

Keyword(s):

Seismic Response ◽

Radial Displacement ◽

Time History ◽

Good Prediction ◽

3D Analysis ◽

Combination Rules ◽

Principal Axes ◽

Artificial Records ◽

The Mean ◽

Irregular Bridges

The seismic responses of continuous multi-span reinforced concrete (RC) bridges were predicted using inelastic time history analyses (ITHA) and incremental dynamic analysis (IDA). Some important issues in ITHA were studied in this research, including: the effects of using artificial and natural records on predictions of the mean seismic demands, effects of displacement directions on predictions of the mean seismic response, the use of 2D analysis with combination rules for prediction of the response obtained using 3D analysis, and prediction of the maximum radial displacement demands compared to the displacements obtained along the principal axes of the bridges. In addition, IDA was conducted and predictions were obtained at different damage states. These issues were investigated for the case of regular and irregular bridges using three different sets of natural and artificial records. The results indicated that the use of natural and artificial records typically resulted in similar predictions for the cases studied. The effect of displacement direction was important in predicting the mean seismic response. It was shown that 2D analyses with the combination rules resulted in good predictions of the radial displacement demands obtained from 3D analyses. The use of artificial records in IDA resulted in good prediction of the median collapse capacity.

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Maximum Total Point Motion of Five Points Versus All Points in Assessing Tibial Baseplate Stability

Journal of Biomechanical Engineering ◽

10.1115/1.4051347 ◽

2021 ◽

Author(s):

Abigail Niesen ◽

Anna L Garverick ◽

Maury Hull

Keyword(s):

Degrees Of Freedom ◽

Stability Limit ◽

3D Models ◽

Six Degrees Of Freedom ◽

Percent Error ◽

Model Based ◽

Point Motion ◽

The Mean ◽

The Difference ◽

Total Point

Abstract Maximum total point motion (MTPM), the point on a baseplate that migrates the most, has been used to assess the risk of tibial baseplate loosening using radiostereometric analysis (RSA). Two methods for determining MTPM for model-based RSA are to use either 5 points distributed around the perimeter of the baseplate or to use all points on the 3D model. The objectives were to quantify the mean difference in MTPM using 5 points vs. all points, compute the percent error relative to the 6-month stability limit for groups of patients, and to determine the dependency of differences in MTPM on baseplate size and shape. A dataset of 10,000 migration values was generated using the mean and standard deviation of migration in six degrees of freedom at 6 months from an RSA study. The dataset was used to simulate migration of 3D models (two baseplate shapes and two baseplate sizes) and calculate the difference in MTPM using 5 virtual points vs. all points and the percent error (i.e. difference in MTPM/stability limit) relative to the 6-month stability limit. The difference in MTPM was about 0.02 mm, or 4% percent relative to the 6-month stability limit, which is not clinically important. Furthermore, results were not affected by baseplate shape or size. Researchers can decide whether to use 5 points or all points when computing MTPM for model-based RSA. The authors recommend using 5 points to maintain consistency with marker-based RSA.

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Explainable Prediction of Whether The Acetabular Cup Is Placed in The “Safe Zone” from X-ray Images

10.1109/bibm52615.2021.9669453 ◽

2021 ◽

Author(s):

Fuchang Han ◽

Shenghui Liao ◽

Chao Xiong ◽

Haitao Wei ◽

Renzhong Wu ◽

...

Keyword(s):

Safe Zone ◽

Acetabular Cup ◽

X Ray

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The anatomic rationale for transforaminal endoscopic interbody fusion: a cadaveric analysis

Neurosurgical FOCUS ◽

10.3171/2015.10.focus15389 ◽

2016 ◽

Vol 40 (2) ◽

pp. E12 ◽

Cited By ~ 15

Author(s):

Mitchell Hardenbrook ◽

Sergio Lombardo ◽

Miles C. Wilson ◽

Albert E. Telfeian

Keyword(s):

Surface Area ◽

Soft Tissues ◽

Safe Zone ◽

Large Area ◽

Nerve Roots ◽

Disc Space ◽

Endoscopic Techniques ◽

Pars Interarticularis ◽

The Mean ◽

Cadaveric Analysis

OBJECTIVE The authors describe a cadaveric analysis to determine the ideal dimensions and trajectory for considering endoscopic transforaminal interbody implantation. METHODS The soft tissues of 8 human cadavers were removed from L-1 to the sacrum, exposing the posterior bony elements. Facetectomies were performed bilaterally at each lumbar level with resection of the pars interarticularis, revealing the pedicles, nerve roots, and interbody disc space. Each level was digitally photographed with a marker for scale and evaluated with digital analysis software. The traversing and exiting nerve roots and pedicle margins were identified, and the distances between these structures and their relationships to the surrounding structures were documented. RESULTS The dimensions of 2 areas were measured: the working triangle and safe zone. The working triangle is the triangle between the exiting and traversing nerve roots above the superior margin of the inferior pedicle. The safe zone is the trapezoid bounded by the widths of the superior and inferior pedicles between the exiting and traversing nerve roots. The mean surface area for the working triangle was 1.83 cm2, with L5–S1 having the largest area at 2.19 cm2. The mean surface area of the safe zone was 1.19 cm2, with L5–S1 having the largest area at 1.26 cm2. At the medial border of the pedicle extending superiorly, there were no nerve structures within 1.19 cm at any level. On the lateral border of the pedicle, the exiting nerve root was closer superiorly, with the closest being 0.3 cm. CONCLUSIONS The working triangle is a relatively large area. The safe zone, just superior to the pedicle, is free of nerve structures. By utilizing the superior border of the pedicle, the disc space can be accessed within this safe zone without risk of injury to the nerves. A thorough understanding of foraminal anatomy is fundamental for considering how to safely access the disc space, thereby utilizing less invasive endoscopic techniques, and is an important first step in considering what shapes and sizes of interbody implants and retractors are feasible for use in the foramen.

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