Quantification of Lumbar Lordosis by Tactile and Non Tactile Methods: A Revisit
Correspondence Address :
Dr. Zubia Veqar,
Associate Professor, Department of Centre for Physiotherapy and Rehabilitation Sciences, Jamia Millia Islamia, New Delhi, India.
Lumbar lordosis alteration results in various disabilities and common problem like low back pain among others which severely impacts the quality of life of a person. This paper focuses on postural evaluation used to identify this alteration, which till date has received little attention even though it is an important outcome measure in various experimental studies. This review focuses on both quantitative and qualitative postural evaluation methods. Conventional methods ranges from visual observation method to gold standard method like radiography and various other non invasive methods like photogrammetric, flexicurve, spinal mouse, inclinometer. However, recent research suggests some 3 Dimensional (3D) analysis methods like 3D radiographs, inertial sensors and posturometer. There is a lack of consensus on the most suitable method of this evaluation hence, the selection is difficult for clinical as well as research purposes. Although there are few reviews available, neither of them has attempted to establish the pros and cons of all these methods. This review provides a comprehensive overview of different 2D, 3D, tactile and non tactile methods or tools that have been developed to measure posture or shape of lumbar spine. This review will also provide practical recommendations to researchers as well as clinicians about the tool selection for lumbar lordosis assessment.
Cobb’s angle, Inclinometer, Lumbar spine, Photogrammetry, Posture, Posturometer
Lumbar lordosis is the anterior convexity in the mid-sagittal plane. It compensates for the inclined sacrum and to avoid anterior inclination. It gives lumbar spine toughness and ability to resist compressive forces. Any alteration in the lumbar lordosis due to congenital condition, trauma, degenerative and inflammatory conditions, compressive forces is transferred to the intervertebral disc through vertebral bodies and can cause low back pain and disabilities. Hence, assessment using reliable methods is used for measuring this alteration of curve and for adequate restoration of lumbar lordosis (1),(2).
A variety of postural assessment methods have been used for clinical and research purposes. Some are conventional (non tactile or tactile methods), while some are advanced (non tactile or tactile methods).
In light of the recognition that lumbar lordosis assessment plays an important role in the prevention and management of low backache and its associated problems, its assessment needs to be given due importance. The primary aim of this review was to provide the readers with a comprehensive information regarding different tools and instruments used for assessing it. It further aimed at finding the most appropriate method among many on the basis of cost, availability, portability, reliability, validity, and ease to use. This information will help researchers as well as clinicians to decide about the most suitable tool/ method which can be used on their subjects/patients for the lumbar lordosis assessment.
TWO-DIMENSIONAL ANALYSIS OF POSTURE
Methods of Measurement
Visual observation method
It is one of the oldest, easiest and most commonly used method for assessment of posture in clinical practice as it doesn’t require any tool. The main disadvantage of this method is its inability to do a quantitative assessment which leads to variability. It also fails to diagnose minor postural alteration (3).
A study was done by Fedorak C et al., for evaluation of reliability of visual assessment for lumbar lordosis (4). It was reported poor (k<0.40) inter-rater and fair (k=0.50) intra-rater reliability. Another study conducted by Iunes DH et al., compared the inter-rater reliability between visual and photogrammetry method in 21 volunteers aged between 22 to 26 years (3). Inter-rater reliability for lumbar lordosis measurement by visual method was 28.6%. The result of both studies concluded that it has poor inter-rater agreement. With this method of postural assessment, reliable results cannot be obtained so more accurate methods should be used in clinical practice.
Radiography, considered as the gold standard method of postural assessment allows the quantification of the anteroposterior curvature of spine, which is important for structural stability, protection of spinal cord and spinal segment mobility (5). Assessment of lumbar lordosis by lateral radiograph is done routinely and cobb method is the most commonly used technique. Cobb’s angle is measured through the intersection of line drawn from endplate of one vertebra to the endplate of another vertebrae (1),(6) and usually superior endplate of L1 segment and superior endplate of S1, segment is used for this assessment (1),(7),(8). Hicks GE et al., determined the inter-rater reliability (0.98), MDC (3.90) and SEM (1.99 degree) of 4-line cobb method for measuring lumbar lordosis and Intraclass Correlation Coefficient (ICC) value after 2 years (0.81) (9). Chung NS et al., determined the validity and reliability of spinopelvic and lumbar lordosis measurement by lateral lumbar radiograph and compared it with lateral whole radiograph (10). They reported similar correlation coefficient 0.93-0.95 and intra and inter observer ICC values as > 0.75 for both. Even though the reliability of both the measurements were similar; lateral lumbar radiograph has certain advantage over lateral whole- spine radiograph like special film is nonessential, radiograph is easy to obtain and radiation exposure is lesser. Although studies concluded excellent reliability of radiographic method but the radiation exposure is an important health concern along with its cost (11).
Photogrammetry is a non invasive method used by healthcare professionals and researchers, as it allows precise evaluation by recording the postural changes over multiple frames. It is helpful for giving information in sagittal and frontal planes (12).
Drzal-Grabiec J et al., evaluated the validity of this method with radiographic method for measuring cobb angle and size of anteroposterior curvature of spine among participants (n=50) aged between 35 to 65 years. A significant correlation was reported between these methods for length of lordosis (r-value=0.88; p-value <0.001) and cobb’s angle (r-value=0.30; p-value <0.001) (13). Other validity studies reported no significant difference for lumbar lordosis angle (p-value=0.817) for photogrammetric and inclinometer in healthy elderly women (14). The validity of prediction equation from skin surface is (r-value >0.85) for T10-S2 level (5). Apart from validity its reliability was also examined well in the literature with its ICC values ranging from (0.98-0.99) and (0.97-0.99) for inter and intra-rater reliability respectively (5).
Numerous studies have reported the use of photogrammetric method for postural evaluation as it is:
(i) Non invasive tool which provide precise qualitative postural evaluation;
(ii) Good agreement with radiograph;
(iii) Repeatability and also;
(iv) Reduces exposure to radiation during radiographic evaluation.
The main limitation associated with this method is the possibility of error while marking the points and their positioning on the computer screen and it is indistinct how photogrammetric technique is utilized to screen postural treatment or to record posture in observational studies (12), (13).
Tactile Methods of Measurement
This method is used in healthy and patient population from children (15) to adolescents, and adults to analyse spinal curvature (16). It has a malleable ruler which is moulded to the back to trace the shape of the spine onto paper, which is followed by calculation of angle of curvature of spine (17).
The reliability studies conducted in the literature among healthy population reported ICC value for lumbar length and width ranging from (0.72-0.74) and (0.56-0.58) for intrarater and inter-rater reliability respectively (16). Furthermore, de Oliveira TS et al., reported excellent inter and intra rater reliability with ICC values 0.83 and 0.78 respectively (18). The results of both studies showed that flexicurve is a reliable tool to assess the lumbar curvature in sagittal plane.
Validity is not very extensively studied, however a study conducted by de Oliveira TS et al., demonstrated strong correlation between radiographic measurement and flexicurve (r=0.60). The limitation associated with flexicurve measurement are the following (15),(16),(18):
• Firstly, difficulty in moulding the flexicurve in the lumbar spine which causes greatest variability in the measurements.
• Secondly, difficulty in palpation of anatomical landmarks in the lumbar region.
• Thirdly, high chances of measurements error due to patient and examiner variability during data collection and angle measurement, also lack in the concurrent validation to ensure its diagnostic capacity.
It is a hand-held, non invasive device with inbuilt accelerometers and small wheels that roll along the length of spine to record the distance and alteration of inclination with respect to the plumb line as well as spinal angle and shape in frontal and sagittal plane, regional kyphosis and lordosis, mobility of the thoracic and lumbar spine, mobility and posture of single vertebral segments, hypomobility and hypermobility of a particular segment, postural competence, posture and mobility of the sacrum/pelvis, posture of the upper body in space (19),(20).
Various reliability studies were conducted to measure the spinal curvature in sagittal and frontal plane among healthy participants. The ICC value for lumbar lordosis ranges from (0.90-0.99) and (0.87-0.99) for intrarater and inter-rater reliability respectively (19),(21). Miyazaki J et al., reported ICCs of 0.94 and 0.89 over skin and clothing respectively (22). Russell BS et al., reported high reliability with ICC values >0.99 of Spinal Mouse unit in measuring lumbar lordosis by use of wooden spine model among 50 participants with or without high- heeled shoes (23). The result of above-mentioned studies showed that Spinal Mouse is a reliable skin- surface device to measure lumbar lordosis in sagittal and frontal plane (22),(23).
Validity of Spinal Mouse in sagittal plane measurement has not been established yet (23). There has been difference in the lumbar lordosis measurements using Spinal Mouse as reported by various authors. Liberg EM et al., reported a mean lordosis of 15°; Keller S et al., reported about 27°; Takihara Y et al., below 20°; and Miyazaki J et al., 19° and 20° over skin and clothing respectively (24),(25),(26). Spinal Mouse measurements are not correlated with radiographic measurement as
(i) Measurement using skin surface device follow line of posterior elements while X-ray measures uses vertebral bodies;
(ii) Distribution of subcutaneous tissue mainly in the lumbar region (19),(21), but comparable with other skin surface devices.
Majority of the studies mentioned above was conducted among healthy asymptomatic participants, there are chances that the use of Spinal Mouse may be more difficult for symptomatic patients.
Inclinometer is a reliable, handy, affordable and non- invasive device which is used to assess the anteroposterior curvature of the spine and helps the clinician to diagnose or to record patient progress efficiently (14),(27). The baseline digital inclinometer offers the speed and ease of use of a digital display. It can be used in conjunction with a second unit for neck and back measurements. Baseline gravity inclinometer and Bubble inclinometer also provides accurate range of motion measurements which can be read directly from the dial. They are used for diagnosis in hospitals, clinics and tracking the progress of therapy (28).
Various authors reported the reliability of inclinometer in measuring lumbar range of motion and lumbar lordosis. Good to excellent intrarater reliability has been reported with ICCs value ranging between (0.90-0.95) for lumbar lordosis measurement using inclinometer among healthy subjects (27),(29). Ng JK et al., (29) measured lumbar lordosis with inclinometer at T12-L1 and L5-S1 level. Van Blommestein, AS et al. (27) calculated the lumbar lordosis at T12-L1 and S2-S3 using Isomed Inclinometer (Isomed, 975 Sandy Blvd., Portland, OR 97214) which consists of a protractor with a freely swinging pointer and two feet that project from its base. Czaprowski D et al. (30) measured the lumbar lordosis using Saunders Digital Inclinometer (Baseline Digital Inclinometer, The Saunders Group Inc, Chaska, MN, USA) in healthy subjects by setting the inclinometer at lumbosacral junction. It was found to have good intrarater reliability with Cronbach’s alpha coefficient (0.87), but significant difference was reported between inter rater measurements (p=0.02). Inclinometer is a reliable tool to assess posture in both asymptomatic and symptomatic individuals. MacIntyre NJ et al., reported the interrater (0.64), intrarater (0.94) reliability of Saunders Digital Inclinometer in measuring spinal curvature of postmenopausal women with osteoporosis (31). MacIntyre NJ et al., determined the interdevice reliability with ICC value (0.97) and Standard Error of Measurement (SEM) (1.33°) using IONmed mobile phone application and digital inclinometer in individuals with osteoporosis and osteopenia (32). Inclinometer is a reliable tool in assessing posture, classification of women with postmenopausal osteoporosis and increased risk of fracture, monitoring progression and response to intervention aimed to improve abnormal posture (31),(32).
Limitations include (33),(34):
• Measurement in single plane (sagittal);
• Higher Body Mass Index (BMI) can make the palpation of landmarks difficult;
• Error in the measurement can be due to inability to maintain constant pressure during movement;
• Misplacement of device or holding the inclinometer slightly off plumb.
Reliability studies of ihandy smartphone application
Smartphones have become our new friends. A free software has been developed to evaluate the posture called as iHandyÂ®. It is available on phones that uses android?SUP?TM#SUP# operating system as well as iPhoneÂ®. This smartphone application can be used as an alternative to inclinometer from accessibility perspective. It provides the capacity to convert the phone into an inclinometer using a built-in tilt sensitive system. The reliability of ihandy smartphone application has been found with ICCs value 0.96 and 0.81 for inter and intrarater reliability respectively using iPhoneÂ® model 4 with iHandyÂ® level application (iPhoneÂ® is a trademark of Apple Inc, Cupertino, CA). It has a build-in accelerometer and digital display to show angle (34). Concurrent validity for ihandy and bubble inclinometer was comparable with r=0.86 (34). Similarly, Koumantaki GA et al., establishes the intrarater reliability (0.93,0.96) for male and female respectively, Standard Error of the Measurement (SEM) (2.13), Minimum Detectable Change (MDC) (5.9) using ihandy level smartphone among healthy adults (33).
Although inclinometer is a reliable instrument but it may not be available in every clinical setting. Studies confirms that mobile phone application offers a quick, convenient, easily accessible and alternative method for assessing sagittal plane spine curvature in clinical settings. Both studies were conducted in young population, so the result cannot be generalized to older population, more studies should be done in older, symptomatic group to increase generalizability (32),(33),(34).
THREE-DIMENSIONAL ANALYSIS OF POSTURE
Method of Measurement
3D radiographic imaging
Biplanar radiographic or open magnetic resonance imaging are used to assess 3D spinal and pelvic alignment, vertebral and intervertebral orientation. Gangnet N et al., and Janssen MMA et al., conducted studies to assess spinopelvic alignment using Biplanar radiographic technique, which provides high-definition digital radiograph which further uses 8-10 times lesser radiation dose than conventional imaging among asymptomatic subjects (35),(36). It was found that Pearson correlations exist between pelvic incidence, L1-S1 lordosis (R-value= -0.40, p-value= 0.02); pelvic radius-S1 angle, pelvic radius-L4 lordosis (R-value= 0.72, p-value< 0.0001); sacral slope, L1-S1 lordosis (R-value=-0.64, p-value< 0.0001); and T12-S1 lordosis, T1-T12 kyphosis (R-value=-0.60, p-value= 0.005) (35). The inter-rater and intra-rater reliability ranges from (0.97-1.00), (0.95-1.00) respectively among asymptomatic subjects (36),(37).
The advantage of 3D imaging techniques are:
• It allows better understanding of 3D aspects of posture (35),
• Higher reproducibility and quicker processing once the user is familiar (37)
Inertial sensors are objective measurement tools, used to measure spinal motion or evaluation of spinal shapes (38). Vision- based Inertial sensor system consist of high-speed cameras, reflective markers or 3D cameras. Vicon is one of the most commonly used marker-based vision sensor system in research and clinical setting (39). It is an advanced 3-dimensional motion analysis system for measurement. Surface markers positioned on the body and infrared cameras are used to detect the movement of markers precisely (40).
The Cartesian Optoelectronic Dynamic Anthropometric (CODA) motion analysis system is a 3-Dimensional kinematic analysis instrument. It is a highly reliable and valid tool for measuring cervical range of motion (41), upper extremity kinematics (42). O’Sullivan K et al., reported the intra (0.75-0.97) and inter rater (0.57-0.95) reliability of upper and lower lumbar spine using CODA motion analysis system (43).
This marker-based vision system has certain disadvantages.
• Firstly, it requires large laboratory setup with expensive equipment.
• Secondly, installation of setup is time consuming and require technical expertise.
• Thirdly, soft tissue artefacts due to incorrect marker positioning may affect the measurement accuracy (39).
Other portable, non invasive wearable sensors used in the posture assessment are E-textile, wearable spine monitoring system and Epionics Spine. Electronic textile (E-textile) has electronic components or sensors such as Inertial Measurement units (IMUs), LEDs, capacitive, resistive or inductive sensors embedded within the fabric. The advantage of E textiles is that it is light weight, small- sized fabric that allow unassuming monitoring (44). A study was done by Sardine E et al., to detect the posture with wearable T- shirt, an inductive sensor was integrated in the T-shirt. It measures the deformation applied on the T- shirt due to lengthening or straightening of the posture which will generate change in impedance (45).
Another wearable sensor used by Voinea GD et al., was “wearable Monitoring System” to generate the shape of spine (38). It has following components: A shirt on which sensors are embedded to detect movement and a controller, used to record data from sensors which is then transmitted to smartphone, so that individual can visualize posture. It has five sensors evenly distributed on the entire spine to detect curvature.
Epionics spine system is an advancement of former SpineDMS system and is used for assessment of thoraco-lumbar posture and motion using strain-gauge technology (46). Inbuilt accelerometer allows the additional detection of orientation of the upper body relative to the earth’s gravitational field. The system is portable and lightweight. It is advantageous because it assesses the lumbar spine during activities of daily living. Consmuller T et al., investigated the intra-rater reliability and compare normative data in healthy subjects using Epionics spine. Significant correlation was exhibited with ICC value 0.85. The lordosis angle during standing measured with Epionics spine was 32.4±9.7 degree (47). The device is also capable of detecting movements out of sagittal plane but certain limitations are also reported like difficulty in determining a curvature in subjects with short height as the same sensor strip size is used for all heights, slippage of sensor strips, also this device measures the shape of the back and not shape of the spine, so the measurements of subjects with higher BMI can differ considerably. A brief summary of existing sensing systems for measurement of lumbar lordosis is given in (Table/Fig 1).
Tactile Method of Measurement
Posturometer-S is a non invasive device designed to analyse body posture. It consists of three coupled systems:• Mechanical- uses a pointing stick to indicate position of measured point,
• Electronic-calculate the position of marked points
• Informatique-used to analyse the results.
Its setup includes measuring device, platform for subjects, seat and computer set (48),(49). It also helps in determining parameters of angular and linear in the planes (50). Posturometer is used to measure angle of lumbar lordosis among children with different body type, children with hearing impairment which will help in early correction of posture (48),(50). The main limitation the authors reported in the studies was that the posturometer-S was not user-friendly, consumes area and requires an intensive understanding of the instrumentation along with training before it can be used (51).
The present article has reviewed a number of methods used for lumbar lordosis assessment, including visual observation, radiography and various other non invasive methods like photogrammetric, flexicurve, Spinal Mouse, Inclinometer and some 3-dimensional analysis methods like 3D radiographs, Inertial sensors and posturometer, and their possible clinical application as well as advantages and disadvantages. Each methods/tool reviewed here comes with its own set of strengths and limitations. The most common method which is used to assess posture in clinical practise is the visual observation method, but it is unable to provide the assessor with a reliable and valid quantitative tool. With this method, quantitative data cannot be obtained as well as there is difficulty in assessing minor posture alteration and possesses poor interrater reliability. Hence, it’s usage should be discouraged in research as well as clinical settings.
Radiography is considered as the gold standard method of postural assessment. But its risk of exposure to radiation and cost limits its use in clinical settings and this further encourages the use of non invasive methods like, photogrammetry, flexicurve, spinal mouse, inclinometer Photogrammetry is capable of giving information in sagittal and frontal planes (12). This method has been compared with visual, and radiographic method. Flexicurve also has good reliability, but limited number of validity studies are available for this method, has limited availability. It also has high chances of measurement error during data collection and angle measurement which limits its use in clinics (15),(16),(18). Spinal Mouse, Inclinometer are some other non invasive reliable devices but may not be available in every clinical setting. As a result, convenient, easy, accessible, reliable smartphone application such as “ihandy” can be used as an alternative method for posture analysis (14),(27).
Some of the 3-dimensional methods are also used for posture assessment like 3D radiographic imaging, inertial sensors, raster stereography, posturometer. These methods and tools can give information about the posture in transverse, sagittal and frontal plane, but they have certain limitations like they are expensive, not user friendly, also require large laboratory settings to measure posture.
The evidence reviewed support the conclusion that photogrammetry and iHandy smartphone application are reliable, quick, convenient, non-invasive methods which can be used to measure posture of lumbar spine. The use of these methods is recommended for future studies in different population to increase the generalizability of these methods.
Date of Submission: Jan 21, 2022
Date of Peer Review: Feb 24, 2022
Date of Acceptance: Mar 04, 2022
Date of Publishing: Jun 01, 2022
• Financial or Other Competing Interests: None
• Was Ethics Committee Approval obtained for this study? NA
• Was informed consent obtained from the subjects involved in the study? NA
• For any images presented appropriate consent has been obtained from the subjects. NA
PLAGIARISM CHECKING METHODS:
• Plagiarism X-checker: Jan 22, 2022
• Manual Googling: Feb 24, 2022
• iThenticate Software: May 11, 2022 (27%)
ETYMOLOGY: Author Origin
- Emerging Sources Citation Index (Web of Science, thomsonreuters)
- Index Copernicus ICV 2017: 134.54
- Academic Search Complete Database
- Directory of Open Access Journals (DOAJ)
- Google Scholar
- HINARI Access to Research in Health Programme
- Indian Science Abstracts (ISA)
- Journal seek Database
- Popline (reproductive health literature)