Spinopelvic mobility App
The assessment of the parameters involved in spinopelvic jucture are of paramount importance for spine and joint replacement surgeon. The dynamic interplay between flexibility and balance around the axis of gravity determine the type and the amount of influence in spine and hips. Radiographic parameters to evaluate objectively the spinopelvic saggital balance are Pelvic incidence (PI), Sacral slope (SS), Pelvic Tilt (PT), Lumbar lordosis (LL) and Combined Sagittal Index (CSI). Drawings in patients X-rays and precise measurements are important in order to quantify the magnitude of spinal deformities, to monitor the success or failure of treatment and thus optimise the management of patients according to the severity of the imbalance or even to identify patient at risk of degenerative spondylolisthesis or disk herniation.
Awareness of this phenomenon by hip and spine surgeons and pre and post operative evaluation of the hips help guide the surgeon to the ideal location for cup implantation or to address the spine or hip pathology accordingly. Radiographic measurement in lateral radiographs in sitting and standing positions of Pelvic incidence (PI), Sacral Tilt (ST), Ante-Inclination (AI), Sacro-acetabular angle (SAA) , Pelvic femoral Angle Angle (PFA) and Combined Sagittal Index (CSI) are of paramount
Radiographic measurement in lateral radiographs in sitting and standing positions of Pelvic incidence (PI), Sacral Tilt (ST), Ante-Inclination (AI), Sacro-acetabular angle (SAA) , Pelvic femoral Angle Angle (PFA) and Combined Sagittal Index (CSI) are calculated by the app in blink of eye.
Radiographic measurement in lateral radiographs in sitting and standing positions of Pelvic incidence (PI), Sacral Tilt (ST), Ante-Inclination (AI), Sacro-acetabular angle (SAA) , Pelvic femoral Angle Angle (PFA) and Combined Sagittal Index (CSI) are calculated by the app in blink of eye.
Awareness of this phenomenon by hip and spine surgeons and pre and post operative evaluation of the hips help guide the surgeon to the ideal location for cup implantation or to address the spine or hip pathology accordingly. Radiographic measurement in lateral radiographs in sitting and standing positions of Pelvic incidence (PI), Sacral Tilt (ST), Ante-Inclination (AI), Sacro-acetabular angle (SAA) , Pelvic femoral Angle Angle (PFA) and Combined Sagittal Index (CSI) are of paramount
Hip instability due to spinopelvic mobility, specifically the move from standing to sitting, and the subsequent changes in pelvic orientation is associated with late dislocations in hip replacement surgery and revision. Awareness of this phenomenon by hip and spine surgeons and pre and post operative evaluation of the hips help guide the surgeon to the ideal location for cup implantation or to address the spine or hip pathology accordingly.
Hip instability due to spinopelvic mobility, specifically the move from standing to sitting, and the subsequent changes in pelvic orientation is associated with late dislocations in hip replacement surgery and revision. Awareness of this phenomenon by hip and spine surgeons and pre and post operative evaluation of the hips help guide the surgeon to the ideal location for cup implantation or to address the spine or hip pathology accordingly.
Radiographic measurement in lateral radiographs in sitting and standing positions of Pelvic incidence (PI), Sacral Tilt (ST), Ante-Inclination (AI), Sacro-acetabular angle (SAA) and Pelvic femoral Angle Angle (PFA) and Combined Sagittal Index (CSI),are of paramount importance. These data measured in standing and in sitting X-rays and compared both with normal reference data may help to evaluate and plan treatment strategies. In clinical settings measuring all these angles is cumbersome and App comes to help the surgeon to do the job without loosing time.
The Spinopelvic Mobility App is medical software aimed for orthopaedic surgeons, providing tools that allow doctors to:
-Securely import medical images directly from the camera or stored photos.
-By marking few points at the image of X-ray, the App calculates and offers a very convenient way to determine the most accurate possibly way at once, Pelvic incidence (PI), Sacral Tilt (ST), Ante-Inclination (AI), Sacro-acetabular angle (SAA) and Pelvic femoral Angle Angle (PFA), and Combined Sagittal Index (CSI) . According to measured parameters in standing and sitting lateral x- rays the app helps to identify patterns of spinopelvic mobility namely normal, hypermobile or three patterns of spinal imbalance: hips maintained in anterior tilt (stuck standing), hips held in posterior tilt (stuck sitting), or stiff hips or kyphotic sacrum.
-Save the planned images, for later review or consultation.The measured values are compared by normal reference databases and also data are exported as txt file, ready to print or to input as cells to excel for research.
-The app allows choosing points in an in independent manner from order and thus it is easy to be learned .
All information received from the software output must be clinically reviewed regarding its plausibility before patient treatment! Spinopelvic Mobility App indicated for assisting healthcare professionals. Clinical judgment and experience are required to properly use the software.The software is not for primary image interpretation.
In a busy everyday practice, the examiner have to draw lines in X-rays or in clinical settings, this it is time consuming and cumbersome. Accessory instruments like protractors, hinged goniometers, well sharped pencils, rulers or even transparent papers must be available. The app offers a very convenient and accurate way to perform most common radiographic measurements for spine, at the spinopelvic juncture in a blink of an eye in front of your screen. The build in feature of the app, allows results to be categorized may help decide what could be considered normal or pathologic.
This App is particular useful in clinical settings where you need a quick results without losing time. Please see tutorial videos at the developer’s web site www.orthopractis.com
Reference
1.Lum ZC ,et alThe Current Knowledge on Spinopelvic Mobility.J Arthroplasty. 2018 Jan;33(1):291-296.
2.Stefl M et all Spinopelvic mobility and acetabular component position for total hip arthroplasty. Bone Joint J. 2017 Jan;99-B(1 Supple A):37-45.
3.Tezuka T, Heckmann N, Bodner R, Dorr LD. Functional safe zone is superior to the Lewinnek
safe zone for total hip arthroplasty: why the Lewinnek safe zone is not always predictive of stability. J Arthroplasty. 2019;34:3–8.
4. Heckmann N, Stefl M, Trasolini N, McKnight B, Ike H, Dorr LD. Late dislocation following total hip arthroplasty. JBJS. 2018;100:1845–53.
5.Grammatopoulos G, Falsetto A, Sanders E, et al. Integrating the Combined Sagittal Index Reduces the Risk of Dislocation Following Total Hip Replacement. J Bone Jt Surg - Am 2022;104
397-411.
HOW TO MEASURE WITH THE APP:
The app offers a very convenient way to determine the most accurate lines in order to measure the angles. Once you load or capture the patient’s image by default the button “Std” is highlighted, meaning that you have to input preferably the standing X-ray to measure.
With the transparent circular template you aim to locate the posterior corner on the top margin of S1 of the sacrum and by clicking the button “point” the P1 point is marked. Then by clicking the “point”, button at the anterior corner of the superior end plate of S1 vetebra, the point P2 is marked. Next you aim at center of the femoral heads and by clicking the ‘point’ button you mark the center of femoral head (C3). Pelvic incidence Angle (PI), Sacral Tilt Angle (ST), are calculated.
Next you aim at the most anterior point of the acetabulum and by pressing the “point” button, the (A4) point is marked by the same way at the most posterior point of the acetabulum wall, thus the (A5) point is marked.The angle subtended by (A4A5) line to the horizontal reference line is the Anteinclination (AI) Angle which is measured. By pressing the button “point” you mark the F6 point by aiming the the most anterior surface of femoral shaft, the Pelvic femoral Angle Angle (PFA) is calculated. The Sacro-acetabular angle (SSA) between a line from anterior to posterior wall and sacral slope is also calculated. The results are compared and categorised as normal or abnormal and also the range of normal values are printed on the screen.
An asterisk appeared above of button Std meaning that the measured data are stored in ram and not discarded. By importing the new sitting X-ray the data from previous measurement namely of standing X-ray are not lost. Once you press the “Stt” button which is highlighted you can measure by selecting points in exact the same way. The same points as mentioned above for the standing X-ray. The results are of sitting X-ray are printed also on the screen and compared. Finishing the measurements the asterisk appears above button “Stt” meaning that the measured data are stored in ram. The app calculates and compares with normal reference values and a screen message appears. The detailed analysis of data by comparing the standing and sitting position is exported with the save button. The txt file can be open with notepad or numbers externaly. Please see tutorial videos
Pelvic incidence Angle (PI) Angle centered at mid-sacral base, perpendicular to the sacral base and center of the femoral heads Constant value that does not change with sitting and standing.Pelvic incidence is a static measurement so is the same for both standing and sitting (normal 53° ± 11°)
Sacral Tilt Angle (ST) : angle between the sacral slope and a horizontal reference line
ST is a dynamic measure of pelvic tilt from the anteriorly tilted standing position (normal = 40° ± 10°) to posterior tilt with sitting (normal =20° + 9° ).
Anteinclination (AI): angle subtended between a line from anterior to posterior wall (A4A5) line to the horizontal reference line, is a dynamic measurement of the opening of the acetabular component with posterior tilt of the pelvis.
(normal values standing 35° ± 10° , sitting 52° + 10° ),
AI values a >75 in sitting, femoral head can dislocate posteriorly due to falling out of cup, a term coined “drop out dislocation.
Δ(ΑΙ) is the difference between the standing and sitting of AI, Δ(AI) <5 acetabulum does not accommodate in spinopelvic motion and is at pathologic risk for dislocation(stiff acetabulum) consider Dual mobility articulation .
Pelvic femoral Angle Angle (PFA) centered at femoral head, between mid-sacral base and down femoral shaft.During spinopelvic motion, the femur flexes along with sacral tilt to accommodate a 90 sitting pattern. Pelvic femoral angle is measured at femoral extension standing (180° ± 15° normal range ),and at flexion sitting (125° + 12° normal range).
Δ (PFA) is the difference between the standing and sitting of PFA normal value 50°–75°
Sacro-acetabular angle (SSA) a line from anterior to posterior wall and sacral slope is also calculated.
∆ST is the difference between the standing and sitting of ST
∆ST <10° =stiff hips needed inclination near 45°, and anteversion of 20° to 25° with combined anteversion of 35° to 50°, to open the orientation of acetabulum to compensate for loss of the pelvic movement
∆ST > 30°= hypermobility : lesser inclination of 35° to 40° and lesser anteversion of 15° to 20° is necessary to prevent excessive verticality of the acetabular component with sitting
Combined Sagittal Index (CSI) is the sum of AI and PFA (CSI = AI+PFA) at standing and at sitting position and and predicts the risk of direction of dislocation in THA ,
If CSI standing of >243 ° high risk for anterior dislocation, red letters.
if CSI standing < 216° High risk for posterior disloacation ,red letters.
If CSI sitting of ≤ 151° increased risk for posterior dislocation, red letters
Otherwise green letters normal.
In quick view,
P1 :-the posterior corner on the top margin of S1 vetebra of the sacrum
P2 :-at the anterior corner of the superior end plate of S1 vetebra,
C3 :-center of the femoral head
A4 :- most anterior point of the acetabulum wall,
A5 :-most posterior point of the acetabulum wall
F6 :-most anterior surface of femoral shaft
All information received from the software output must be clinically reviewed regarding its plausibility before patient treatment! Spinopelvic Mobility App indicated for assisting healthcare professionals. Clinical judgment and experience are required to properly use the software.The software is not for primary image
Normal range of values in standing and sitting
