Propagation of Registration Error into Maximum Total Point Motion to Analyze Tibial Baseplate Stability at Six Months Using Marker-Based and Model-Based RSA

2021 ◽  
pp. 110651
Author(s):  
Abigail E. Niesen ◽  
Maury L. Hull
Keyword(s):  
Registration Error ◽  
Model Based ◽  
Point Motion ◽  
Total Point

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

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.

Inducible displacement of cemented tibial components ten years after total knee arthroplasty

2018 ◽  
Vol 100-B (2) ◽  
pp. 170-175 ◽  
Author(s):  
K. Lam Tin Cheung ◽  
B. A. Lanting ◽  
R. W. McCalden ◽  
X. Yuan ◽  
S. J. MacDonald ◽  
...  
Keyword(s):  
Total Knee Arthroplasty ◽  
Internal Rotation ◽  
Knee Arthroplasty ◽  
Weight Bearing ◽  
Prospective Trial ◽  
Radiolucent Lines ◽  
Point Motion ◽  
Total Knee ◽  
One Year ◽  
Total Point

Aims The aim of this study was to evaluate the long-term inducible displacement of cemented tibial components ten years after total knee arthroplasty (TKA). Patients and Methods A total of 15 patients from a previously reported prospective trial of fixation using radiostereometric analysis (RSA) were examined at a mean of 11 years (10 to 11) postoperatively. Longitudinal supine RSA examinations were acquired at one week, one year, and two years postoperatively and at final follow-up. Weight-bearing RSA examinations were also undertaken with the operated lower limb in neutral and in maximum internal rotation positions. Maximum total point motion (MTPM) was calculated for the longitudinal and inducible displacement examinations (supine versus standing, standing versus internal rotation, and supine versus standing with internal rotation). Results All patients showed some inducible displacement. Two patients with radiolucent lines had greater mean standing-supine MTPM displacement (1.35; sd 0.38) compared with the remaining patients (0.68; sd 0.36). These two patients also had a greater mean longitudinal MTPM at ten years (0.64; sd 0.50) compared with the remaining patients (0.39; sd 0.13 mm). Conclusion Small inducible displacements in well-fixed cemented tibial components were seen ten years postoperatively, of a similar magnitude to that which has been reported for well-fixed components one to two years postoperatively. Greater displacements were found in components with radiolucent lines. Cite this article: Bone Joint J 2018;100-B:170–5.

Migration measurement of the cemented Lubinus SP II hip stem – a 10-year follow-up using radiostereometric analysis

2017 ◽  
Vol 62 (3) ◽  
Author(s):  
Stefan Sesselmann ◽  
Yutong Hong ◽  
Frank Schlemmer ◽  
Kurt Wiendieck ◽  
Stephan Söder ◽  
...  
Keyword(s):  
Mean Value ◽  
Global Coordinate System ◽  
Radiostereometric Analysis ◽  
Short Term ◽  
Postoperative Radiograph ◽  
Distal Migration ◽  
Point Motion ◽  
Hip Stems ◽  
Total Point

AbstractIn a previous radiostereometric analysis (RSA) of the Lubinus SP II (Link, Hamburg, Germany), which is one of the most often used cemented hip stems worldwide, our research group detected a very small but statistically significant distal migration of -0.03±0.17 mm 2 years after surgery compared to the postoperative radiograph. Maximum subsidence occurred between 6 and 12 months. The implant appeared to have stabilized after 2 years. The mean value of maximum total point motion (MTPM) was 0.99±0.69 mm, which was detected 2 years after surgery. The purpose of this study was to analyze the migration pattern and to verify the predictive value of short-term RSA of the Lubinus SP II stem after 10 years. After a follow-up of 5 and 10 years, 38 and 27 out of 100 patients remained available for further assessment, respectively. No statistically significant implant translation or rotation was found along or about the axes of the global coordinate system 5 and 10 years after surgery with respect to the postoperative radiograph. Furthermore, the MTPM was stable in both follow-up periods. The results suggest that the Lubinus SP II hip stem is still stable 10 years after surgery, supporting that determining prognosis by short-term RSA follow-up of 2 years could be an appropriate tool for appraisal of implant behavior 10 years after surgery.

Radiostereometric migration analysis of the Cerafit femoral stem: 28 patients followed for 2 years

2016 ◽  
Vol 61 (3) ◽  
pp. 291-298 ◽  
Author(s):  
Franz Tschunko ◽  
Benedikt Wagner ◽  
Yutong Hong ◽  
Stephan Söder ◽  
Rainer Wölfel ◽  
...  
Keyword(s):  
Clinical Outcome ◽  
Femoral Stem ◽  
Harris Hip Score ◽  
Radiostereometric Analysis ◽  
Distal Migration ◽  
Point Motion ◽  
Migratory Pattern ◽  
Migration Analysis ◽  
Total Point

Abstract Radiostereometric analysis (RSA) is the gold standard evaluating micromovements after total hip arthroplasty. The aim of this study was to investigate the migratory pattern of an uncemented femoral stem during the first 2 years after surgery. We followed 28 patients with a mean age of 57 (SD 13) years for the first two postoperative years. Radiostereometric analysis was used to measure the translation and rotation of the femoral component. The Harris hip score (HHS) was determined to evaluate the clinical outcome. No stem had to be revised. The mean HHS advanced from 35 (SD 11) preoperative to 89 (SD 10) 1 year after surgery. At the end of the observation period, mean subsidence of the stem was 0.26 mm (SD 0.82). Maximum total point motion (MTPM) was 1.23 mm (SD 1.22). The main distal migration took place up to 6 weeks after surgery with nearly no further subsidence up to 2 years postoperatively. All the measured migrations of the hip stem were very small. Results of the HHS demonstrate good clinical outcome. Long-term RSA is necessary to assess possible late migration of the Cerafit standard femoral stem.

scholarly journals Intra-operative Clodronate Rinsing Improves the Integration of the Femoral Stem in a Prospective, Double-blinded, Randomized, Placebo-controlled Clinical RSA-study

2021 ◽  
Vol 15 (1) ◽  
pp. 1-12
Author(s):  
Jukka Kiuttu ◽  
Petri Lehenkari ◽  
Hannu-Ville Leskelä ◽  
Olli Yrjämä ◽  
Pasi Ohtonen ◽  
...  
Keyword(s):  
Placebo Group ◽  
Bone Loss ◽  
Femoral Stem ◽  
Harris Hip Score ◽  
Periprosthetic Bone ◽  
Point Motion ◽  
Periprosthetic Bone Loss ◽  
Total Point ◽  
Double Blinded

Background: Periprosthetic bone loss after Total Hip Arthroplasty (THA), detected as an early migration of the prosthesis may predict later loosening of the implant. Objective: We hypothesized that intra-operative bisphosphonate rinsing would reduce bone resorption after THA. It might therefore be possible to achieve better early fixation of the implant. Methods: Nineteen patients suffering from arthrosis were recruited in a prospective, double-blinded, randomized, placebo-controlled clinical pilot trial. Patients were operated with an uncemented Bimetric stem using tantalum markers. The femoral proximal intramedullary canal was rinsed with 1mM clodronate in nine patients and with saline in 10 patients. These patients were followed for two years using radiostereometric analysis (RSA), dual energy x-ray absorptiometry (DXA) and the Harris Hip Score (HHS). Results: We did not found any significant differences between the study groups with regards to the primary output measures (maximum total point motion, MTPM). However, there was evidence that clodronate could affect periprosthetic bone quality; a beneficial effect in BMD in Gruen zone 3 during the two-year follow-up was observed, BMD decreased less in the clodronate group (p = 0.02). The maximal x-translation of the stem at 3-24 months was significantly two-fold, being higher in the placebo group (p = 0.02). The baseline BMD and the maximal total point motion (MTPM) at 3-24 months showed a positive correlation in the clodronate group and a negative correlation in the placebo group. Conclusion: In conclusion, further studies with larger patient groups and longer follow-up periods are needed to estimate the clinical importance of these findings and further to prove if an intraoperative clodronate rinsing prior to application of femoral stem during THA can prevent periprosthetic bone loss. Clinical Trial Registration No.: NCT03803839

A model-based strategy for quadruped running with differentiated fore- and hind leg morphologies

2021 ◽  
Author(s):  
Kuan-Yu Tseng ◽  
Pei-Chun Lin
Keyword(s):  
Ground Reaction Force ◽  
Reaction Force ◽  
Basins Of Attraction ◽  
Quadruped Robot ◽  
Model Based ◽  
Proposed Model ◽  
Point Motion ◽  
Leg Motion ◽  
Natural Dynamics ◽  
Leg Morphology

Abstract This article introduces a model-based strategy for a quadruped robot with differentiated fore- and hind-leg ground reaction-force patterns to generate animal-like running behavior. The proposed model comprises a rigid body and two eSLIP legs with dampers. The eccentric-SLIP (eSLIP) model extends the traditional spring-loaded inverted pendulum (SLIP) model by adding a bar to offset the spring direction. The proposed two-leg eSLIP (TL-eSLIP) model’s fore- and hind legs were designed to have the same offset magnitude but in opposite offset directions, producing different braking and thrusting force patterns. The TL-eSLIP model’s reference leg trajectories were designed based on the fixed-point motion of the eSLIP model. Additionally, the legs were clock torque-controlled to modulate leg motion and stabilize the model to follow its natural dynamics. The model’s equations for motion were derived, and the model’s dynamic behavior was simulated and analyzed. The simulation results indicate that the model with leg offsets and in either trotting or pronking has differentiated leg force patterns, and it is more stable and has larger basins of attraction than the model without leg offsets. A quadruped robot was built for experimental validation. The experimental results demonstrate that the robot with differentiated legs ran with differentiated ground reaction force patterns and ran more stably than another robot with the same leg morphology.

Previously Unrecognized Source of Error in the Change in Maximum Total Point Motion to Determine Continuous Migration of Unstable Tibial Baseplates

2021 ◽  
Author(s):  
Abigail Niesen ◽  
Maury Hull
Keyword(s):  
Stability Limit ◽  
Implicit Assumption ◽  
Independent Variables ◽  
Time Zero ◽  
Error Magnitude ◽  
Point Motion ◽  
The Difference ◽  
Relative Errors ◽  
Total Point ◽  
Source Of Error

Abstract In radiostereometric analysis (RSA), continuous migration denoted as ΔMTPM is the difference between maximum total point motion (MTPM) at 2 years relative to time zero and MTPM at 1 year relative to time zero. Continuous migration has been used to diagnose tibial baseplates as stable versus unstable when compared to a specified stability limit (i.e. value of ΔMTPM). If the same point experiences MTPM at 2 years and at 1 year (usually the case for marker-based RSA), then an implicit assumption is that the migration path between 2 years and 1 year is the same as the path between 1 year and time zero. This paper uses vector analysis to demonstrate a source of error in ΔMTPM not previously recognized and estimates the error magnitude based on the interplay of independent variables which affect the error. The two independent variables which affect the error are the angle between the two migration vectors (i.e., MTPM between time zero and 2 years and MTPM between time zero and 1 year) and the difference in magnitude of the two vectors. The relative error increased in an absolute sense as the angle between the vectors increased and decreased for larger differences in the magnitudes of the two vectors. For magnitude ratios ranging from 1.25 to 2, relative errors ranged from -21% to -3% at 10° and from -78% to -42% at 60°, respectively. Knowledge of these errors highlights a limitation in the use of ΔMTPM not previously recognized.

Radiostereometric migration measurement of an uncemented Cerafit® femoral stem: 26 patients followed for 10 years

2018 ◽  
Vol 63 (6) ◽  
pp. 657-663 ◽  
Author(s):  
Stefan Sesselmann ◽  
Yotung Hong ◽  
Frank Schlemmer ◽  
Isabell Hussnaetter ◽  
Lutz A. Mueller ◽  
...  
Keyword(s):  
Internal Rotation ◽  
Late Onset ◽  
Femoral Stem ◽  
Short Term ◽  
Long Term Stability ◽  
Point Motion ◽  
Total Point ◽  
Short Time ◽  
Novel Design

Abstract Radiostereometric analysis (RSA) is the gold standard for evaluating micromotions of orthopaedic implants. The method is applied for identifying novel design weaknesses in endoprostheses. Current research frequently assesses relatively short time periods. Short-term RSA studies have been widely used for predicting the long-term stability of many hip prosthetic designs, but only a few studies have focused on uncemented hip implants, especially for extended periods. The purpose of this study was to analyse the migration pattern of the Cerafit® femoral stem within 10 years and to verify the predictive value of short-term RSA after 2 years for this uncemented femoral hip stem. Twenty-six patients were followed for 10 years. Ten years after implantation, a mean subsidence of 0.22 mm±0.56 mm, a mean internal rotation of 0.59°±1.67° and a mean maximum total point motion (MTPM) of 1.28 mm±0.54 mm were detected. The main migration took place in the first 6 weeks after surgery (subsidence of 0.36 mm±0.73 mm; internal rotation of 0.62°±1.49°, MTPM of 1.05 mm±0.68 mm). All the migration values measured were small. No late-onset migration was observed. This study suggests that the Cerafit® implants are stable after 10 years. Thus, RSA could be the best tool to assess long-term implant behaviour.

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