2 Lecturer in Sports Rehabilitation, Division of Rehabilitation Studies, University of Bradford, UK
Design and setting: Observational laboratory study
Main outcome measures: Performance of 5 participant’s single leg squat and hop landing was assessed using 3-D motion capture and the findings of this compared to the qualitative scoring scheme.
Conclusion: The scores generated by the qualitative scoring scheme used showed excellent association with the corresponding data from 3-D motion capture, implying the measurement tool shows criterion validity.
Results: The range of percentage of agreement between the qualitative and 3-D score was for all subjects across both tasks 95.6- 100%. The kappa measure of agreement was k = 0.9 for hop landing and k = 0.97 for single leg squat.
The purpose of this study was to undertake preliminary work to examine the level of agreement and validity of a novel observational movement assessment score and its ability to evaluate trunk and lower limb alignment during two different single leg loading tasks compared to 3-D motion capture. The aim being to assess the validity of the qualitative score acquired during single leg squatting and hop landing against 3-D kinematics.
3D analyses:A twelve-camera OQUS (Qualisys, Gothenburg, Sweden) motion analysis system sampling at 100 Hz, and a force platform (AMTI BP400600, USA) sampling at 1000 Hz, was used to collect the kinematic data. Prior to testing reflective markers were attached to the participants at the anterior superior iliac spines, posterior superior iliac spines, iliac crest, greater trochanters, medial and lateral femoral condyles, medial and lateral malleoli, posterior calcanei, and the head of the first, second and fifth metatarsals. These markers were used to define the anatomical reference frame and centres of rotations of the joints. Five rigid plates, each consisting of four non-collinear markers, were secured with elastic bandages on the anterolateral aspect of the thigh, shank and around the pelvis. These rigid bodies were used as tracking markers to track the movement of each segment during the movement trial. The use of a rigid marker set of four non-collinear markers for tracking purposes has previously been shown to be the optimal configuration in comparison to using individual skin markers and other rigid arrays [10]. To track the motion of the thoracic spine, a rigid plate with three attached markers, was attached to the sternum and in order to define an anatomical reference frame for this segment, markers were attached to C7, the spinous process of the sixth thoracic vertebra (T6), the suprasternal notch and the xiphoid process. The calibrated anatomical systems technique (CAST) was employed to determine the movement of each segment and anatomical significance during the movement trials [11]. A static trial was carried out initially to allow for later identification of the anatomical and tracking markers in the Qualysis software prior to extraction to post-processing software and define the subjects neutral (anatomical) zero position which are referred back to this position. Post-processing calculation of the kinematic and kinetic time series data was conducted using Visual3D motion capture software (Version 4.21, C-Motion Inc., Rockville, MD, USA). Motion and force plate data were filtered using a Butterworth 4th order bi-directional low-pass filter with cut-off frequencies of 12 Hz for kinematic data and 25 Hz for force plate data. Three trials were recorded and mean data from the three trials of each task was used for comparison to the qualitative score.
Qualitative assessment: Qualitative assessment of the two tasks was made from digital video footage captured simultaneously during the 3D assessment. A digital video camera (Sony Handycam DCR-HC37) sampling at 25 Hz was wall mounted at a height of 60 cm and 10 metres away from the force plates. Digital video footage was recorded at a standard 10x optical zoom throughout each trial in order to standardize the camera position.
A qualitative scoring system was devised by the primary author (LH) based on the previously reported scoring systems of Crossley, et al. [1] and Whatman, et al. [3]. It involved dichotomous scoring of the movement strategy occurring in individual body regions (arm, trunk, pelvis, thigh, knee, foot). Scoring was defined as a zero for appropriate strategy and one for inappropriate movements, for each region with best overall score being 0 and worst 10 points. The scoring sheet is shown in Table 1. Typical errors are shown in Table 2. Optimal behaviour involved minimal deviation or body movement from that prescribed, that is arm do not move, trunk is slightly flexed, but held still, pelvis stays in mid position with minimal tilt, thighs stay parallel and approximately vertically orientation, patellae point towards middle of foot and foot demonstrates minimal wobble.
Analysis: A single examiner (LH) (blind to 3-D data) assessed the videos of the single leg squat and single leg landing of each subject; each video was viewed three times at standard speed and then scored using the qualitative scoring sheet. A second investigator (AM) then analysed the findings of qualitative assessment and compared them to those of the 3-D assessment. Prior to viewing the qualitative scores the same investigator (AM) reduced the 3-D kinematic data for each participant and each joint motion, into dichotomous scores (0=alignment/motion of segment/joint within range of normative data; 1= alignment/ motion exceeds range of normative data) corresponding to the movement individual segment movement strategy within the qualitative scoring sheet this reflected the method used by Onate et al. [3]. The normative range was based on those reported in the review of Fox et al. [12].
Statistical analysis: To assess the agreement between 3-D score and qualitative score, a kappa statistical analysis was used.
Qualitative analysis of single leg loading Date: Patient: Condition: Left Right Bilateral |
|||
QASLS |
Task: Single leg squat Single leg step down Single leg hop for dist |
Left |
Right |
Arm strategy |
Excessive arm movement to balance |
||
Trunk alignment |
Leaning in any direction |
||
Pelvic plane |
Loss of horizontal plane |
||
Excessive tilt or rotation |
|||
Thigh motion |
WB thigh moves into hip adduction |
||
NWB thigh not held in neutral |
|||
Knee position |
Patella pointing towards 2nd toe (noticeable valgus) |
||
Patella pointing past inside of foot (significant valgus) |
|||
Steady stance |
Touches down with NWB foot |
||
Stance leg wobbles noticeably |
|||
Total |
QASLS category |
Error |
Optimal |
Sub-optimal example |
Arm strategy |
Excessive arm movement to balance |
|
|
Trunk alignment |
Leaning in any direction |
|
|
Pelvic plane |
Loss of horizontal plane |
|
|
Excessive tilt or rotation |
|
||
Thigh motion |
WB thigh moves into hip adduction |
|
|
NWB thigh not held in neutral |
|
||
Knee position |
Patella pointing towards 2ndtoe (noticeable valgus) |
|
|
Patella pointing past inside of foot (significant valgus) |
|
||
Steady stance |
Touches down with NWB foot |
||
Stance leg wobbles noticeably |
Task |
Criteria |
||||||||||||||||||||||
Single leg squat (SLS) |
Arm |
Trunk |
Pelvis Frontal |
Pelvis Rotation |
WB Hip |
NWB Hip |
Knee Valgus minor |
Knee Valgus Major |
WB Excess motion |
NWB Touch down |
|||||||||||||
Participant |
Gender |
Q |
3D |
Q |
3D |
Q |
3D |
Q |
3D |
Q |
3D |
Q |
3D |
Q |
3D |
Q |
3D |
Q |
3D |
Q |
3D |
||
1 |
Male |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
1 |
1 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
||
2 |
Male |
0 |
0 |
0 |
0 |
1 |
1 |
0 |
0 |
1 |
1 |
0 |
0 |
1 |
1 |
0 |
0 |
0 |
0 |
0 |
0 |
||
3 |
Male |
0 |
0 |
1 |
1 |
1 |
1 |
0 |
1 |
1 |
1 |
0 |
0 |
1 |
1 |
1 |
1 |
0 |
0 |
0 |
0 |
||
4 |
Female |
0 |
0 |
1 |
1 |
0 |
0 |
1 |
1 |
1 |
1 |
0 |
0 |
1 |
1 |
0 |
0 |
0 |
0 |
0 |
0 |
||
5 |
Female |
0 |
0 |
1 |
1 |
1 |
1 |
1 |
0 |
1 |
1 |
0 |
0 |
1 |
1 |
1 |
1 |
0 |
0 |
0 |
0 |
||
Task |
Criteria |
||||||||||||||||||||||
Single leg land (SLL) |
Arm |
Trunk |
Pelvis Frontal |
Pelvis Rotation |
WB Hip |
NWB Hip |
Knee Valgus minor |
Knee Valgus Major |
WB Excess motion |
NWB Touch down |
|||||||||||||
Participant |
Gender |
Q |
3D |
Q |
3D |
Q |
3D |
Q |
3D |
Q |
3D |
Q |
3D |
Q |
3D |
Q |
3D |
Q |
3D |
Q |
3D |
||
1 |
Male |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
1 |
1 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
||
2 |
Male |
0 |
0 |
0 |
0 |
1 |
1 |
0 |
0 |
1 |
1 |
0 |
0 |
1 |
1 |
0 |
0 |
1 |
1 |
0 |
0 |
||
3 |
Male |
0 |
0 |
1 |
1 |
1 |
1 |
1 |
0 |
1 |
1 |
0 |
0 |
1 |
1 |
1 |
1 |
1 |
1 |
1 |
1 |
||
4 |
Female |
0 |
0 |
1 |
1 |
0 |
0 |
1 |
1 |
1 |
1 |
1 |
0 |
1 |
1 |
0 |
0 |
0 |
0 |
1 |
1 |
||
5 |
Female |
0 |
0 |
1 |
1 |
1 |
1 |
1 |
1 |
1 |
1 |
1 |
1 |
1 |
1 |
1 |
1 |
1 |
1 |
0 |
0 |
The qualitative scoring system used was based on those previously reported in the literature which had attempted to analyse single leg squat and had shown good to excellent intra and inter tester reliability.[1,7] The scheme incorporated the region criteria similar to that used by both Crossley, et al. [1] and Whatman, et al[7], following the assertion from both Onate, et al. [3], Chmielewski, et al. [4] and Whatman, et al. [7] that this increased content validity. Similarly, a dichotomous scale was used when classifying motion within each of the regions which was shown to increase reliability [7]. The scheme used in this study was modified from those studies to also take into account trunk motion which Crossley, et al. [1] and Myer, et al. [6] regarded as a significant factor in the alteration of lower limb moments.
- Crossley KM, Zhang WJ, Schache AG, Bryant A, Cowan SM. Performance on the single leg squat task indicates hip abductor muscle function. Am J Sports Med. 2011; 39(4):866-873.
- Hewett TE, Myer GD, Ford KR, Heidt RS Jr, Colosimo AJ, McLean SG, et al. Biomechanical measures of neuromuscular control and valgus loading of the knee predict anterior cruciate ligament injury risk in female athletes: a prospective study. Am J Sports Med. 2005; 33(4):492-501.
- Onate J, Cortes N, Welch C, Van Lunen BL. Expert versus novice interrater reliability and criterion validity of the landing error scoring system. J Sport Rehabil. 2010; 19(1):41-56.
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- Padua DA, Marshall SW, Boling MC, Thigpen CA, Garrett WE Jr, Beutler AI. The Landing Error Scoring System (LESS) Is a valid and reliable clinical assessment tool of jump-landing biomechanics: The JUMP-ACL study. Am J Sport Med. 2009; 37(10):1996-2002.
- Munro A, Herrington L, Carolan M. Reliability of two-dimensional video assessment of frontal plane dynamic knee valgus during common athletic screening tasks. J Sport Rehabil. 2012; 21(1):7-11.
- Manal K, McClay I, Stanhope S, Richards J, Galinat B. Comparison of surface mounted markers and attachment methods in estimating tibial rotations during walking: an in vivo study. Gait Posture. 2000; 11(1):38-45.
- Cappozzo A, Catani F, Leardini A, Benedetti MG, Croce UD. Position and orientation in space of bones during movement: Experimental artefacts. Clin Biomech. 1996; 11(2):90-100.
- Fox AS, Bonacci J, McLean SG, Spittle M, Saunders N. What is normal? Female lower limb kinematic profiles during athletic tasks used to examine anterior cruciate ligament injury risk: asystematic review. Sports Med. 2014; 44(6):815-832.
- Landis JR, Koch GG. The measurement of observer agreement for categorical data. Biometrics. 1977; 33(1):159-174.