Effect of Leg Length Discrepancy on Trunk Muscle Fatigue and Unintended Trunk Movement

Evaluation of the effect of heel lift on postural stability and symmetry of muscle activity

BACKGROUND

Although a leg length inequality (LLI) has the effect on the performed movement, more complex indices for the evaluation of kinematic variables of postural stability and a symmetry of a muscle activity during standing in subjects with the LLI were never used before.

OBJECTIVE

The objective is to present appropriate parameters for an evaluation of kinematic variables of postural stability and muscle activity during standing, i.e. to consider EMG signals, in patients with LLI.

METHODS

New indices are offered, such as a sway velocity (i.e. the mCTSIB method) and a modified symmetry index (SI), for a quantitative evaluation of EMG signals. The set of data for evaluating the effect of a heel lift was measured on patients with the LLI and healthy volunteers.

RESULTS

Prior to the heel lift application, significant statistic differences were found between the mCTSIB of patients and the CG. These differences were no longer statistically significant after the heel lift was applied. As for the SI, the lowest values were found in the CG, while the greatest values were collected among patients before applying the heel lift.

CONCLUSIONS

The results point out the benefits of using the newly applied indices in patients with the LLI. Both methods may become useful tools for the evaluation of the physical state of patients with the LLI in a medical practice.

Normative 3D opto-electronic stereo-photogrammetric posture and spine morphology data in young healthy adult population

Design: Observational cross-sectional study. The current study aims to yield normative data: i.e., the physiological standard for 30 selected quantitative 3D parameters that accurately capture and describe a full-skeleton, upright-standing attitude. Specific and exclusive consideration was given to three distinct categories: postural, spine morphology and pelvic parameters. To capture such 3D parameters, the authors selected a non-ionising 3D opto-electronic stereo-photogrammetric approach. This required the identification and measurement of 27 body landmarks, each specifically tagged with a skin marker. As subjects for the measurement of these parameters, a cohort of 124 asymptomatic young adult volunteers was recruited. All parameters were identified and measured within this group. Postural and spine morphology data have been compared between genders. In this regard, only five statistically significant differences were found: pelvis width, pelvis torsion, the “lumbar” lordosis angle value, the lumbar curve length, and the T12-L5 anatomically-bound lumbar angle value. The “thoracic” kyphosis mean angle value was the same in both sexes and, even if, derived from skin markers placed on spinous processes it resulted in perfect agreement with the X-ray based literature. As regards lordosis, a direct comparison was more difficult because methods proposed in the literature differ as to the number and position of vertebrae under consideration, and their related angle values. However, when the L1 superior–L5 inferior end plate Cobb angle was considered, these results aligned strongly with the existing literature. Asymmetry was a standard postural-spinal feature for both sexes. Each subject presented some degree of leg length discrepancy (LLD) with μ = 9.37mm. This was associated with four factors: unbalanced posture and/or underfoot loads, spinal curvature in the frontal plane, and pelvis torsion. This led to the additional study of the effect of LLD equalisation influence on upright posture, relying on a sub-sample of 100 subjects (51 males, 49 females). As a result of the equalisation, about 82% of this sub-sample showed improvement in standing posture, mainly in the frontal plane; while in the sagittal plane less than 1/3 of the sub-sample showed evidence of change in spinal angles. A significant variation was found in relation to pelvis torsion: 46% of subjects showed improvement, 49% worsening. The method described in study presents several advantages: non-invasive aspect; relatively short time for a complete postural evaluation with many clinically useful 3D and 2D anatomical/biomechanical/clinical parameters; analysis of real neutral unconstrained upright standing posture.

Do Patients' Perceptions of Leg Length Correlate With Standing 2- and 3-Dimensional Radiographic Imaging?

BACKGROUND

This study compared 2- and 3-dimensional (2D and 3D) radiographic measurements of anatomical and functional leg length and knee coronal and sagittal alignments and correlated these measurements with patients' leg-length perceptions.

METHODS

Patients without symptomatic spinal pathology, previous surgery of the spine, and lower extremities (140 lower extremities) were evaluated on EOS images obtained in standing position. Numerous measurements of each limb were compared to the contralateral limb. All 2D/3D measures were evaluated and compared for repeatability and reproducibility.

RESULTS

Mean 2D functional and anatomical lengths were 78.7 cm (64.7-88.4, confidence interval [CI] 95%: 77.4-80) and 78.3 cm (64.9-87.9, CI 95%: 77-79.6), respectively. Mean 3D functional and anatomical lengths were 78.9 cm (65.1-88.7, CI 95%: 77.6-80.2) and 78.9 cm (65.6-88.3, CI 95%: 77.8-80.5), respectively (P < .001). Mean 2D and 3D knee varus/valgus angles were -1.9° (-26.4 to 9.1, CI 95%: -3.5 to -0.7) and -0.9° (-19.2 to 11.8, CI 95%: -2.4 to 0.2), respectively (P = .004). Multiple regression analysis found that patients with >10° of flexum/recurvatum were 2.1× more likely to perceive unequal length (P < .1). Patients with irreducible varus/valgus knee deformity were 4× more likely to perceive unequal length (P < .04).

CONCLUSION

EOS imaging allows more accurate assessment of anatomical and functional lengths. Patients' perceptions of lower extremity length may correlate more closely with coronal and sagittal alignments of the knee than with femoral or tibial length. This study highlights the importance of physical examination of all the joints and 3D measurements in functional standing position.

Effects of pelvic skeletal asymmetry on trunk movement: three-dimensional analysis in healthy individuals versus patients with mechanical low back pain

STUDY DESIGN

Comparative analysis and correlational research design were used to investigate the association between anthropometry and biomechanical performance among asymptomatic subjects and patients with low back pain (LBP).

OBJECTIVES

To examine the association between pelvic asymmetry and patterns of trunk motion in asymptomatic and LBP subjects. Secondary objective was to investigate the association between restricted trunk motion, laterality of referred pain, and pelvic asymmetry.

SUMMARY OF BACKGROUND DATA

Subtle pelvic asymmetry (exhibited as either lateral pelvic tilt or iliac rotational asymmetry), which is common among normal individuals, has not been convincingly linked to abnormalities in back movements. Given the difficulty in diagnosing most LBP, a classification using pelvic asymmetry and patterns of movement could be helpful in establishing a rational treatment plan.

METHODS

Fifty-nine subjects with no history of LBP and 54 patients with mechanical unilateral LBP were tested. An anthropometric frame was used to measure pelvic asymmetry in standing. Dynamic motion data, comprised of the principal and coupled movements, were collected using the Qualysis Motion Capture System.

RESULTS

While the groups did not differ in the total range of lumbar movement, the LBP group exhibited significantly higher asymmetry in the principal motion. The groups differed significantly in the pattern of coupled rotation during lateral flexion. Asymmetry in lumbar lateral flexion was highly related to two types of pelvic asymmetry: lateral pelvic tilt (LPT) and iliac rotation asymmetry (IRA). Asymmetry in lumbar axial rotation was highly related to IRA but weakly related to LPT.

CONCLUSIONS

This study demonstrates objective differences in patterns of lumbar movement between asymptomatic subjects and patients with LBP. The study also demonstrates that subtle anatomic abnormality in the pelvis is associated with altered mechanics in the lumbar spine. We suggest that asymmetry of lumbar movement may be a better indicator of functional deficit than the absolute range of movement in LBP.

Erector Spinae and Quadratus Lumborum Muscle Endurance Tests and Supine Leg-Length Alignment Asymmetry: An Observational Study

OBJECTIVE

To determine if there is an association between supine leg-length alignment (LLA) asymmetry and the endurance of the erector spinae (ES) and quadratus lumborum (QL) muscles.

METHODS

Forty-seven subjects (21 women; average age, 36 years old) were tested for ES endurance using the Biering-Sorensen (B-S) test, and 69 (31 women; average age, 34.5 years) were tested for QL endurance. Subjects were examined for supine LLA and tested for ES and QL muscle endurance. The muscle endurance times were compared against those who did and did not demonstrate LLA asymmetry and the side of the "short leg."

RESULTS

In the B-S test, volunteers with LLA asymmetry (n = 27) had a mean endurance time of 89.7 seconds (SD, 43.3), and the no-LLA asymmetry group (n = 20) had a mean endurance time of 161.5 seconds (SD, 57.1), a significant difference (P < .001). In the QL test, after correction for the effects of sex and exercise, those with a right "short leg" (n = 22) had a right QL endurance time of 25.9 seconds (SE, 4.2) and a left QL endurance time of 34.7 seconds (SE, 4.3). The right QL endurance time was significantly different from those subjects with balanced legs (P = .001). Those with a left "short leg" (n = 20) had a left QL endurance time of 28.6 seconds (SE, 4.7) and a right QL endurance time of 38.1 seconds (SE, 4.5). Both QL endurance times were significantly different from those with balanced leg-length (P = .002 and .016, respectively).

CONCLUSION

This study suggests that, using the B-S test, the group of volunteers who demonstrated a commonly used sign of subluxation/joint dysfunction, supine LLA asymmetry, had a decreased endurance times over those who did not. The QL endurance tests showed that the QL muscle ipsilateral to the supine short leg had significantly decreased endurance times over the same-side QL fatigue times in the no leg-length asymmetry group.

Anatomic and functional leg-length inequality: a review and recommendation for clinical decision-making. Part I, anatomic leg-length inequality: prevalence, magnitude, effects and clinical significance

BACKGROUND

Leg-length inequality is most often divided into two groups: anatomic and functional. Part I of this review analyses data collected on anatomic leg-length inequality relative to prevalence, magnitude, effects and clinical significance. Part II examines the functional "short leg" including anatomic-functional relationships, and provides an outline for clinical decision-making.

METHODS

Online database--Medline, CINAHL and MANTIS--and library searches for the time frame of 1970-2005 were done using the term "leg-length inequality".

RESULTS AND DISCUSSION

Using data on leg-length inequality obtained by accurate and reliable x-ray methods, the prevalence of anatomic inequality was found to be 90%, the mean magnitude of anatomic inequality was 5.2 mm (SD 4.1). The evidence suggests that, for most people, anatomic leg-length inequality does not appear to be clinically significant until the magnitude reaches approximately 20 mm (approximately 3/4").

CONCLUSION

Anatomic leg-length inequality is near universal, but the average magnitude is small and not likely to be clinically significant.

Anatomic and functional leg-length inequality: a review and recommendation for clinical decision-making. Part II. The functional or unloaded leg-length asymmetry

Background

Part II of this review examines the functional "short leg" or unloaded leg length alignment asymmetry, including the relationship between an anatomic and functional leg-length inequality. Based on the reviewed evidence, an outline for clinical decision making regarding functional and anatomic leg-length inequality will be provided.

Methods

Online databases: Medline, CINAHL and Mantis. Plus library searches for the time frame of 1970–2005 were done using the term "leg-length inequality".

Results and Discussion

The evidence suggests that an unloaded leg-length asymmetry is a different phenomenon than an anatomic leg-length inequality, and may be due to suprapelvic muscle hypertonicity. Anatomic leg-length inequality and unloaded functional or leg-length alignment asymmetry may interact in a loaded (standing) posture, but not in an unloaded (prone/supine) posture.

Conclusion

The unloaded, functional leg-length alignment asymmetry is a likely phenomenon, although more research regarding reliability of the measurement procedure and validity relative to spinal dysfunction is needed. Functional leg-length alignment asymmetry should be eliminated before any necessary treatment of anatomic LLI.