Influence of vaginal birth on lumbopelvic muscle mechanical properties on urinary incontinence

OBJECTIVE

To identify differences in the muscle mechanical properties of the pelvic floor (PF) and lumbar paravertebral (LP) muscles between young nulliparous and uni/multiparous women. Secondarily, specific behaviors, depending on the presence or absence or urinary incontinence (UI), were also researched.

DESIGN

Case-control study.

SETTING

Higher education institution.

PARTICIPANTS

One hundred young women participated, divided into two groups depending on whether they had vaginal birth (nulliparous or uni/multiparous). Each group included women with and without UI.

MAIN MEASURES

A muscle mechanical properties (tone, stiffness, decrement-inverse of elasticity-, and viscoelastic properties: relaxation and creep) assessment of the PF and LP muscles were performed with a hand-held tonometer.

RESULTS

Tone and stiffness of both sides of the PF presented group by UI interaction (p < 0.05), with uni/multiparous women with UI showing higher tone and stiffness compared to multiparous women without UI. In LP muscles, uni/multiparous women showed greater tone and stiffness on the right and left sides [-2.57 Hz (95% confidence interval -4.42,-0.72) and -79.74 N/m (-143.52,-15.97); -2.20 Hz (-3.82,-0.58) and -81.30 N/m (-140.66-,21.95), respectively], as well as a decrease in viscoelastic properties compared to nulliparous women [relaxation: 2.88 ms (0.31,5.44); creep: 0.15 (0.01,0.30); relaxation: 2.69 ms (0.13,5.25); creep: 0.14 (0,0.28), respectively].

CONCLUSIONS

Vaginal birth and UI have a differential influence on the muscle mechanical properties of the PF and LP muscles. The determination of muscle mechanical properties by externally applied hand-held tonometry improves the knowledge of the lumbopelvic status, with applicability in clinical and research fields.

Between-sexes differences in lumbopelvic muscle mechanical properties of non-climacteric adults: a cross-sectional design

The lumbopelvic muscle mechanical properties (MMPs) are clinically relevant, but their dependence on sex remains unknown. Therefore, this study aimed to identify if lumbopelvic MMPs depend on the sex in a young adult population. Thirty-five healthy nulliparous women and 35 healthy men were analyzed (age range: 18-50). Lumbopelvic MMPs, that is, tone, stiffness, elasticity, relaxation and creep, assessed with MyotonPRO®, and pelvic floor (PF) health questionnaires were compared between-sexes. Intra-group correlations between sociodemographic and clinical data, and MMPs were also determined. The MMPs of PF were different between healthy non-climacteric adults of both sexes, with women showing higher values of tone and stiffness and lower values of elasticity and viscoelastic properties than men (in all cases, p < 0.03). At lumbar level, tone and stiffness were higher for men at both sides (in all cases, p < 0.04), and relaxation was lower at left side (p = 0.02). The MMPs showed few correlations with sociodemographic data within women. However, within males, there were positive correlations for PF stiffness and viscoelastic parameters with age, BMI and function (0.334 < r < 0.591) and, at lumbar level, negative correlations for tone and stiffness ( - 0.385 < r < -0.590) and positive correlations for viscoelastic properties (0.564 < r < 0.719), with BMI. This indicated that between-sexes differences of lumbopelvic MMPs depend on the specific location of assessment in healthy non-obese young individuals. Women show higher tone and stiffness and lower elasticity and viscoelasticity than men, at PF level.

Influence of Spinal Movements Associated with Physical Evaluation on Muscle Mechanical Properties of the Lumbar Paraspinal in Subjects with Acute Low Back Pain

This research aimed to identify changes in muscle mechanical properties (MMPs) when a standardized sequence of movements is performed and to determine the influence of acute low back pain (LBP) and age on the MMPs. Socio-demographic, clinical variables and MMPs were collected in 33 patients with LBP and 33 healthy controls. A 2 × 2 × 2 (group × age × time) analysis of variance (ANOVA) mixed model was used to determine the effect of the study factors on the different MMPs. There were no significant triple interactions. After the movements, tone and stiffness increased 0.37 Hz and 22.75 N/m, respectively, in subjects <35 years, independent of their clinical status. Relaxation showed differences by age in healthy subjects and creep in LBP subjects. Furthermore, elasticity was higher in <35 years (p < 0.001) without the influence of any other factor. In conclusion, sequenced movements can modify tone and stiffness as a function of age, while age-associated changes in viscoelastic characteristics depends on pain but not on movements. The MMPs should be assessed, not only at the beginning of the physical examination at rest, but also along the patient’s follow-up, depending on their pain and age, in a clinical setting.

Absolute and Relative Reliability of the Assessment of the Muscle Mechanical Properties of Pelvic Floor Muscles in Women with and without Urinary Incontinence

An analysis of the muscle mechanical properties (MMPs) of the pelvic floor muscles (PFMs) is relevant for understanding the physiopathology of urinary incontinence (UI). However, there is no objective and reliable methodology currently available for quantifying the MMPs of PFMs. Thus, the objective was to determine the intra-rater and inter-rater reliability of the MMPs of PFM assessment with a hand-held tonometer device, called the MyotonPRO, in young women with and without UI. Sociodemographic and pelvic floor questionnaires, plus MMPs of PFMs were assessed in 38 nulliparous women with UI and 40 matched healthy women by two trained physiotherapists on two different occasions, 48-72 h apart. Good to excellent absolute reliability was found for tone, stiffness, and decrement of both intra- and inter-rater analyses in both study groups (Intraclass Correlation Coefficient ranged from 0.75 to 0.92), with a trend of lower values for relaxation and creep. The standard error of measurement (SEM) did not achieve 10% of the mean values for any MMPs. The minimum detectable change (MDC) values were also provided for clinical applications. In conclusion, the relative reliability of tone, stiffness, and the assessment of the decrement of PFMs with MyotonPRO is good to excellent for UI and healthy women. The SEM and MDC values were acceptable for their application in clinical settings.

Paravertebral Muscle Mechanical Properties in Patients with Axial Spondyloarthritis or Low Back Pain: A Case-Control Study

Different musculoskeletal disorders are a source of pain in the spinal region; most of them can be divided into mechanical, such as low back pain (LBP), or inflammatory origins, as is the case of axial spondyloarthritis (axSpA). Nevertheless, insufficient information is available about the muscle negative consequences of these conditions. Thus, the objective of this study was to identify whether mechanical muscle properties (MMPs) of cervical and lumbar muscles are different between patients with axSpA, subacute LBP (sLBP), and healthy controls. Furthermore, we aimed identify whether MMPs were related to sociodemographic and clinical variables in various study groups. The MMPs, sociodemographic, and clinical variables were obtained in 43 patients with axSpA, 43 subjects with sLBP, and 43 healthy controls. One-way ANOVAs and ROC curves were applied to identify whether the MMPs could differentiate between the study groups. Intra-group Pearson r coefficients to test the associations between MMPs and the rest of the variables were calculated. The results showed that axSpA subjects have a higher tone and stiffness and a lower relaxation and creep than sLBP and healthy ones (p < 0.05). All lumbar and cervical MMPs, except for decrement, could correctly classify axSpA and healthy subjects and axSpA and sLBP patients (in both cases, Area Under the Curve > 0.8). However, no MMP could differentiate between sLBP and healthy subjects. Each group had a different pattern of bivariate correlations between MMPs and sociodemographic and clinical data, with a worse state and progression of the axSpA group associated with a higher tone and stiffness in both spinal regions. This study supports that MMPs are different and show different patterns of correlations depending on the type of spinal pain.

Mechanical Properties of Lumbar and Cervical Paravertebral Muscles in Patients with Axial Spondyloarthritis: A Case-Control Study

Background: Axial spondyloarthritis (axSpA) affects spinal muscles, due to inflammation and structural damage. The mechanical properties of the muscles, such as tone or stiffness, could be altered in axSpA. The aim of this work is to analyze the mechanical properties of cervical and lumbar spine muscles in axSpA patients and their relationship with metrology measures, function, disease activity, structural damage and quality of life. Methods: axSpA patients and age/gender/BMI matched healthy controls were recruited. The muscle mechanical properties (MMPs), such as tone or frequency, stiffness, decrement (linear elastic properties), relaxation and creep (viscoelastic properties), of cervical (semispinalis capitis) and lumbar (erector spinae) muscles were bilaterally measured at rest using myotonometry. Additionally, conventional metrology, BASMI (metrology index), BASDAI (disease activity index), mSASSS (radiological structural damage index) and SF-12 (health-related quality of life questionnaire) were used in the axSpA group. Between-groups comparison, intra-group correlations and multivariable regression analyses were performed to achieve the study aims. Results: Thirty-four axSpA patients (mean age: 46.21 ± 8.53 y) and 34 healthy volunteers (mean age: 43.97 ± 8.49 y) were recruited. Both in cervical and lumbar spine, linear elastic parameters were significantly higher in axSpA patients in comparison with controls, while viscoelastic parameters were significantly lower. Lumbar muscle frequency, stiffness, relaxation, creep and cervical muscle elasticity were fair to strongly correlated (|0.346| < r < |0.774|) with age, functional status, activity of disease, structural damage and quality of life in axSpA patients. Furthermore, moderate to good fitted multivariate models (0.328 < R² < 0.697) were obtained combining age, conventional metrology, activity of the disease and function for the estimation of cervical and lumbar MMPs. Conclusion: Mechanical properties of spinal muscles of axSpA patients differ from controls. Lumbar and cervical muscles exhibit greater linear elastic properties and lower viscoelastic properties, which are related with age, clinical and psychophysiological features of axSpA.

POS1272 DIFFERENCES IN RANGE OF MOTION AND MECHANICAL MUSCLE CHARACTERISTICS AMONG INFLAMMATORY AND MECHANICAL SPINAL PAIN: A CASE-CONTROL STUDY

Background:

The spinal range of motion (ROM) and the mechanical muscle properties (MMPs) at rest are defined as relevant clinical factors in inflammatory (i.e. axial Spondyloarthritis -axSpA) and mechanical spinal pain (i.e. Mechanical Neck pain -NP- or Mechanical Low Back pain -LBP-). Nevertheless, there is not enough evidence regarding if ROM and MMPs are different in both types of spinal pain.

Objectives:

To identify differences between axSpA patients and NP or LBP subjects, in cervical and lumbar ROMs and MMPs at rest.

Methods:

Subjects with axSpA and with NP or LBP composed the Inflammatory pain Group (IG) and the Mechanical pain Group (MG), respectively. For the analysis of the spinal mobility, two Inertial Measurement Units (IMU) were used. For both spinal regions (cervical and lumbar - Figure 1A,B) 3 repetitions of flexion-extension, lateral-flexion, and rotation were executed separately[1]. A record of the MMPs using a hand myotonometer was made in both lumbar (muscular belly of the erector spinal – Figure 1D) and cervical (the semispinalis capitis muscles at C4 - Figure 1C) spine in prone position with both arms along the body. The MMPs recorded in this study included: frequency (tone), stiffness, decrement (elasticity), relaxation and creep (viscosity). The order of assessments (right/left) was randomized. Since no side-to-side differences in either group were observed, the mean of both sides was considered. Student-t tests were used to compare the groups, and Cohen-d effect size index was estimated as a measure of the size of difference. P<0.05 was considered statistically significant.

Results:

61 subjects in IG (42% women, age 41±12 years, BMI 25±3) and 66 in MG (51% women, age 38±13 years, BMI 25±3) participated in this study. No significant differences were identified in sociodemographic data between both groups. Table 1 shows ROM and MMPs between groups. All lumbar ROMs were significantly lower in the IG, with the different between means achieving the minimum clinical important difference (>8°) for flexion-extension and lateroflexion. On the contrary, the cervical ROMs were not different between groups, and showed the highest variability, probably related to compensatory mechanisms due to lumbar ROMs restrictions. The IG showed greater Lumbar stiffness than the MG with large effect size (d=0.94). No other difference in MMPs was identified in this region (p>0.05). Regarding the cervical region, all MMPs showed differences between groups. Thus, tone, stiffness and elasticity were higher in the IG, while relaxation and viscosity were lower. In all cases, except for decrement, the effect size was from moderate to large (0.6<d<0.8).

Table 1.IG (n=61)MG (n=66)p-valueCohen-dLumbar flexion- extension (°)62.7 ± 20.270.8 ± 17.90.019 *0.42Lumbar rotation (°)25.6 ± 8.330.1 ± 10.10.007 *0.48Lumbar lateral-flexion (°)46.6 ± 12.354.8 ± 10.8<0.001 *0.70Cervical flexion- extension (°)96.5 ± 21.696.2 ± 18.80.9410.01Cervical rotation (°)130.9 ± 27.3131.9 ± 25.60.8170.01Cervical lateral-flexion (°)66.4 ± 21.571.6 ± 15.60.1220.27Lumbar tone (Hz)15.32 ± 3.4014.52 ± 1.930.1290.29Lumbar stiffness (N/m)330.85 ± 56.93272.48 ± 65.590.001 *0.94Lumbar decrement1.33 ± 0.411.29 ± 0.320.4800.10)Lumbar relaxation (ms)19.11 ± 7.5820.23 ± 4.290.3120.18Lumbar creep1.16 ± 0.431.21 ± 0.220.5190.14Cervical tone (Hz)17.27 ± 1.9316.17 ± 1.840.001 *0.58Cervical stiffness (N/m)313.93 ± 54.17282.61 ± 50.070.001 *0.59Cervical decrement1.34 ± 0.231.42 ± 0.180.020 *0.39Cervical relaxation (ms)16.66 ± 2.5218.49 ± 2.74<0.001 *0.69Cervical creep1.02 ± 0.141.13 ± 0.14<0.001 *0.80

Conclusion:

AxSpA patients present lower lumbar ROMs than NP and LBP subjects. Further, posterior cervical MMPs of axSpA are more rigid and less viscoelastic than those of NP and LBP subjects. ROMs and MMPs show a different behavior pattern in cervical and lumbar regions when spinal pain from different origin is assessed.

References:

[1]Measuring Spinal Mobility Using an Inertial Measurement Unit System: A Validation Study in Axial Spondyloarthritis. Diagnostics 10(6):426

Disclosure of Interests:

None declared

Design, Validity, and Reliability of a New Test, Based on an Inertial Measurement Unit System, for Measuring Cervical Posture and Motor Control in Children with Cerebral Palsy

OBJECTIVE

The aim of this study was to design and propose a new test based on inertial measurement unit (IMU) technology, for measuring cervical posture and motor control in children with cerebral palsy (CP) and to evaluate its validity and reliability.

METHODS

Twenty-four individuals with CP (4-14 years) and 24 gender- and age-matched controls were evaluated with a new test based on IMU technology to identify and measure any movement in the three spatial planes while the individual is seated watching a two-minute video. An ellipse was obtained encompassing 95% of the flexion/extension and rotation movements in the sagittal and transversal planes. The protocol was repeated on two occasions separated by 3 to 5 days. Construct and concurrent validity were assessed by determining the discriminant capacity of the new test and by identifying associations between functional measures and the new test outcomes. Relative reliability was determined using the intraclass correlation coefficient (ICC) for test-retest data. Absolute reliability was obtained by the standard error of measurement (SEM) and the Minimum Detectable Change at a 90% confidence level (MDC90).

RESULTS

The discriminant capacity of the area and both dimensions of the new test was high (Area Under the Curve ≈ 0.8), and consistent multiple regression models were identified to explain functional measures with new test results and sociodemographic data. A consistent trend of ICCs higher than 0.8 was identified for CP individuals. Finally, the SEM can be considered low in both groups, although the high variability among individuals determined some high MDC90 values, mainly in the CP group.

CONCLUSIONS

The new test, based on IMU data, is valid and reliable for evaluating posture and motor control in children with CP.