Correlation of Spinopelvic Movement With Lateral Radiographs to Assess Spine Motion Prior to Total Hip Arthroplasty
Phase: NA
Conditions: Spinopelvic Relationships as They Relate to Total Hip Arthroplasty's
Sponsor: Mayo Clinic

 
 
Correlation of Spinopelvic Movement with 
Lateral Radiographs to Assess Spine Motion 
Prior to Total Hip Arthroplasty. 
 
 
NCT05117229 
 
6/21/2021 

6-21-2021 
Correlation of Spinopelvic Movement with Lateral Radiographs to Assess Spine Motion 
Prior to Total Hip Arthroplasty. 
 
Design: Prospective pilot study 
Aims:  
1) To evaluate the correlation between a novel pelvic MetaWear sensor that 
assesses spinopelvic motion with lateral sit-to-stand radiographs.   
2) To evaluate the relationship between a novel pelvic sensor with pelvic tilt, 
sacral slope, and lumbar lordosis.   
Background:  Spinopelvic relationships are increasingly recognized as an important part of 
total hip arthroplasty and determinant of stability after THA.  A number of recent papers in 
the literature have correlated stiffness of the spinopelvic parameters and the potential risk of 
total hip arthroplasty dislocation.  Most commonly, assessment is performed with lateral sit-
to-stand radiographs where changes of less than 10 degrees in sacral slope have been 
described as stiff spines and could represent patients at increased risk of instability.  Given 
the dynamic nature of the hip/spine biomechanics, which is further influenced by relative 
stiffness of the hip/spine complex, it remains to be determined how the patient’s actual 
motion impacts these radiographic parameters. MetaWear sensors positioned on the pelvis 
can potentially provide meaningful spinopelvic motion parameters and could eliminate the 
need for additional radiation needed to obtain lateral radiographs. The correlation between 
the MetaWear sensor obtained spinopelvic motion and radiographic data obtained from the 
more traditional lateral sit to stand radiographs is needed.  
We will prospectively evaluate 40 patients presenting for surgery at the Division of Hip and 
Knee Arthroplasty at Mayo Clinic. An assessment of pelvic motion will be     obtained 
through MetaWear sensors. Data capture will then be verified by the Research Coordinator. 
Preliminary data shows in 2019, OrthAlign, Inc. conducted an internal study utilizing one 
sensor device strapped to the femur and one sensor device attached to the skin by the 
patient’s sacrum using the same devices and adhesive in the proposed study. The study 
included 10 employees with no prior knowledge of everyone pelvic or spinal mobility. A 
physical therapist conducted the study according to the protocol consistently across all 
individuals. Measurements were taken while sitting, standing, and leaning forward. All 
intended data was able to be collected with no adverse events. Across the patient population, 
the average change in pelvic mobility between sitting and standing was 11.86° with a 
standard deviation of 6.99°, minimum of -1.07° and a maximum of 28.25°. In a study using 
radiographs, Seyler et al.1 found an average of 19.2°, standard deviation of 9.9°, min of 1.6°, 
maximum of 37.5° in change in pelvic tilt across 24 subjects. Nine total measurements were 
taken per individual. Three sets of measurements were taken. Each set contained three 
measurements under the same conditions. Between datasets, the sensors were removed and 

re-applied. The standard deviation within and across datasets were calculated for each patient. 
The standard deviation withing datasets was just under 3.0° and the standard deviation across 
datasets was 3.2°. These standard deviations were compared to radiographs study data2. The 
study showed standard deviations between approximated 2.7° and 3.5° for radiograph 
measurements of sacral slope and APP angle during standing and sitting positions. Therefore, 
we concluded our study produce feasible pelvic range of motion results between sitting and 
standing positions with repeatability and reproducibility comparable to radiograph 
technology. 
Methods:  Data from the MetaWear sensors will be collected directly into the sensor and 
downloaded onto a secure Excel sheet after transfer to specialized app on an IPAD. These 
patients will have a lateral sitting and standing lumbar radiographs which will take 
approximately 15 minutes.  All patients will have a modern and innovative MetaWear sensor 
placed on their pelvis which should take an additional 15 minutes to place on the research 
subjects (Figure 1: showing location of the MetaWear sensor placement).  The patients will 
then obtain the appropriate radiographs with the sensors in place and appropriate correlations 
between sensor data and radiographs will be made.  Radiographs being taken include lateral 
sitting, standing, and pelvis images. 
Included Patients:  Age 18+ 
Ability to provide informed consent 
40 total 
Sex: men & women 
Hip pathology: 40 subjects presenting for total hip arthroplasty or joint 
preservation procedures 
Age: 20 patients greater than 70 years, 10 patients between 50-70, and 10 
patients 18-50 
Pregnancy test: Women in childbearing ages between 18 and 50 will be 
required to perform a urine pregnancy test prior to inclusion 
Excluded patients:  Exclude patients with lumbosacral hardware, contralateral THA, or DJD 
in the contralateral hip, pregnant women, those who have an allergy to glue or adhesives, or 
those unwilling to be tested. 
Withdraw Criteria: If a patient is unable to complete the required imaging due to inability to 
sit or stand during radiographs, the patient may withdraw from the research study. Poor 
radiograph images that do not provide appropriate measurements; additionally, if the 
MetaWear sensor is unable to track patient movement.  
Enrollment process:  Patients will be deemed potentially eligible by surgical teams in the 
Division of Hip and Knee Reconstruction and will be approached by a study coordinator from 
the Department of Orthopedic Surgery.  The study coordinator will obtain a master list of 

enrolled patients, managed in Ptrax and will determine if the patient demographics constitute 
an unfilled spot on the list.  If this is the case the study coordinator will discuss the study in 
detail with the patient and if they agree to participate, we will obtain written informed 
consent.  Subjects will receive $25.00 for their participation.  Radiographs for the study that 
are not part of the standard of care and will be covered by the study and not charged to the 
patient or their insurance.   
The main risk of the study is incremental radiation exposure from 2 research related 
radiographs.  An additional risk includes reaction to adhesive tape. No other risks were 
identified. The adhesive tape is a FLEXcon® dermaFLEX™ which meets ISO 10993 
standards for direct skin contact. The contained H-566 adhesive is non-cytotoxic, non-
irritating and non-sensitizing, as defined by the ISO-10993 standard 
The benefit of the study is to improve the future patient care and add to the body of scientific 
knowledge in this important area. Radiographs:  Lateral lumbar radiographs that are not the 
standard of care for hip surgery patients at this time and will be obtained for research 
purposes.   This is a lateral standing and lateral sitting radiograph as part of the research and 
will be covered by the study.   
Post-radiographic evaluation:  Following attainment of all radiographs the investigative team 
will perform measurements on all radiographs including PI, PT, SS, LL.  Interobserver 
reliability statistics will be determined.  Any discrepancies between reviewers of more than 2 
degrees will be resolved by a third reviewer.   
Assessment of pelvic motion will be obtained through the MetaWear sensors.  Preliminary 
data shows (Add the prelim data obtained for health subjects here) Data from the MetaWear 
sensors will be collected directly into the sensor and downloaded onto a secure Excel sheet.   
There will be no post-radiographic study follow-up for the patients.  If a gross abnormality is 
identified on research-related radiographs the patient will be notified by the surgical team.   
Statistical analysis:  No power analysis was performed as this is a pilot study to determine the 
correlations between PI, PT, SS, LL and patient sensor obtained motion. Statistical analyses 
will be performed by Mayo Stats (Budget 2K more or less plus 40% indirect)   
The total of 40 subjects was chosen to allow balance of age, sex, and hip disease status as 
these parameters may influence measurements.   
Following collection and annotation of all data, a password protected spreadsheet on a 
departmental-secured server will be shared with a statistician from the Division of 
Biomedical Statistics and Informatics.  Categorial data will be tabulated as counts and 
percentages and continuous data as means and ranges with standard deviations and 
confidence intervals as appropriate.  Correlations and means between radiographic 
parameters obtained from lateral radiographs will be calculated and correlated with 
spinopelvic motion obtained through the MetaWear sensors.  Sensitivity analysis or adjusted 
analyses will be performed for age, sex, and hip pathology as deemed appropriate by the 
statistician.  

Device Description: 
Each device is a MetaWear, MotionC wearable sensor. The device contains a circuit board 
with a MEMS gyroscope, accelerometer, magnetometer, barometric pressure, and light 
ambient sensor. Not all sensors are used for this study. The circuit is encased in a plastic 
housing. Real-time communication to a tablet is achieved via BluetoothLE wireless 
communication. The device is FCC, CE, IC and RoHS compliant. 
Adverse Events: 
Adverse events will be monitored and reported to the PI who will make the data available to 
the DSMB. However, we do not anticipate any adverse event occurring with the use of such 
sensor technology. The only adverse even would be associated with sensitivity to adhesive 
tape during the MetaWear sensor placement.  
References:  
1 Sutter EG, Wellman SS, Bolognesi MP, Seyler TM. “A Geometric Model to Determine 
Patient-Specific Cup Anteversion Based on Pelvic Motion in Total Hip Arthroplasty.” Adv 
Orthop. 2019 May 2;2019:4780280. doi: 10.1155/2019/4780280. PMID: 31186967; PMCID: 
PMC6521545. 
2 J.-Y. Lazennec, M.-A. Rousseau, A. Rangel, M. Gorin, C. Belicourt, A. Brusson, Y. 
Catonné 
“Pelvis and total hip arthroplasty acetabular component orientations in sitting and standing 
positions: Measurements reproductibility with EOS imaging system versus conventional 
radiographies” 
Revue de Chirurgie Orthopédique et Traumatologique, Volume 97, Issue 4, June 2011, Pages 
375-383