Various Methods for Assessing Static Lower Extremity Alignment: Implications for Prospective Risk-Factor Screenings

Abstract

Context: Accurate, efficient, and reliable measurement methods are essential to prospectively identify risk factors for knee injuries in large cohorts.Objective: To determine tester reliability using digital photographs for the measurement of static lower extremity alignment (LEA) and whether values quantified with an electromagnetic motion-tracking system are in agreement with those quantified with clinical methods and digital photographs.Design: Descriptive laboratory study. Setting: Laboratory.Patients or Other Participants: Thirty-three individuals participated and included 17 (10 women, 7 men; age ¼ 21.7 6 2.7 years, height ¼ 163.4 6 6.4 cm, mass ¼ 59.7 6 7.8 kg, body mass index ¼ 23.7 6 2.6 kg/m 2 ) in study 1, in which we examined the reliability between clinical measures and digital photographs in 1 trained and 1 novice investigator, and 16 (11 women, 5 men; age ¼ 22.3 6 1.6 years, height ¼ 170.3 6 6.9 cm, mass ¼ 72.9 6 16.4 kg, body mass index ¼ 25.2 6 5.4 kg/ m 2 ) in study 2, in which we examined the agreement among clinical measures, digital photographs, and an electromagnetic tracking system. Intervention(s): We evaluated measures of pelvic angle, quadriceps angle, tibiofemoral angle, genu recurvatum, femur length, and tibia length. Clinical measures were assessed using clinically accepted methods. Frontal-and sagittal-plane digital images were captured and imported into a computer software program. Anatomic landmarks were digitized using an electromagnetic tracking system to calculate static LEA.Main Outcome Measure(s): Intraclass correlation coefficients and standard errors of measurement were calculated to examine tester reliability. We calculated 95% limits of agreement and used Bland-Altman plots to examine agreement among clinical measures, digital photographs, and an electromagnetic tracking system.Results: Using digital photographs, fair to excellent intratester (intraclass correlation coefficient range ¼ 0.70-0.99) and intertester (intraclass correlation coefficient range ¼ 0.75-0.97) reliability were observed for static knee alignment and limblength measures. An acceptable level of agreement was observed between clinical measures and digital pictures for limb-length measures. When comparing clinical measures and digital photographs with the electromagnetic tracking system, an acceptable level of agreement was observed in measures of static knee angles and limb-length measures.Conclusions: The use of digital photographs and an electromagnetic tracking system appears to be an efficient and reliable method to assess static knee alignment and limb-length measurements.Key Words: posture, risk factor assessment, digital photographs Key PointsDigital photographs are a reliable tool to assess static knee alignment and limb-length measurements. An electromagnetic tracking system is an efficient and acceptable method to assess static frontal-plane knee alignment and limb-length measures. Incorporating measures of static lower extremity alignment in prospective study designs will help researchers ide...

Pelvic asymmetry as a risk factor for nonspecific chronic low back pain

“…The results of the present study indicated moderate to excellent inter-and intra-rater reliability for distance variables surrounding the pelvis assessed by the GPS, except for the distance between the PSIS and the midline. These results were consistent with those reported in published studies (19,22,23). A common issue related to the reliability of photographic pelvic posture assessments is the repositioning of markers between measurement sessions.…”

“…For inter-rater reliability, a previous study reported an ICC of 0.43 and an SME of 3.99 on the right and an ICC of 0.49 and an SEM of 4.24 degrees on the left for the pelvic tilt angle. An ICC of 0.84 and an SEM of 2.83 degrees on the right and an ICC of 0.89 and an SEM of 2.16 degrees on the left was reported for the Q angle (23). The smaller SEM values observed in the present study compared with previous studies indicates that the GPS has less measurement error that previous methods when measuring angle parameters.…”

“…Parameters that involved the ASIS and PSIS also have higher MDD 90 and SME values for inter-rater reliability than for intra-rater reliability, suggesting more measurement errors occur in assessments between individuals than in assessments within individuals. Muscle contractions and excessive soft tissue surrounding the pelvis made it difficult to locate the PSIS and ASIS landmarks (19,23). This issue did not appear to be improved by thorough training prior to the data collections, which in theory should reduce the landmark repositioning error.…”

“…To date, there is a wide variety of systems that are available for assessments with different levels of reported reliability. Published studies assessing pelvic and lower extremity alignments mostly investigated intra-rater reliability but not interrater reliability (19,22,23). The Global Postural System (GPS) is a recently developed computerized photographic postural assessment system.…”

The association between pelvic asymmetry and non-specific chronic low back pain as assessed by the global postural system

“…To date, there is a wide variety of systems that are available for assessments with different levels of reported reliability. Published studies assessing pelvic and lower extremity alignments mostly investigated intra-rater reliability but not interrater reliability [21,24,25]. The Global Postural System (GPS) is a recently developed computerized photographic postural assessment system.…”