The relationship and discriminatory capability of hip adduction, knee flexion and rearfoot eversion in females with Patellofemoral Pain during stair ascent 1
Danilo de Oliveira Silva, 2,3Christian John Barton, 1Ronaldo Valdir Briani and 1Fábio Mícolis de Azevedo
1
University of State Sao Paulo, Laboratory of Biomechanics and Motor Control, Presidente Prudente, Brazil; Lower Extremity Gait Studies, La Trobe University, Australia; 3Centre for Sports and Exercise Medicine, Queen Mary University of London, London, UK. E-mail:
[email protected] 2
INTRODUCTION Patellofemoral Pain (PFP) development is considered to be multifactorial, with local, proximal, and distal biomechanical factors proposed to be associated. Several theoretical hypotheses’ exist to explain the possible pathomechanisms underlying PFP. However, few studies have evaluated factors at each level concurrently, which is needed to improve our understanding of which may be most important in PFP. Furthermore, previous studies have reported only mean differences between individuals with PFP and matched controls, without any attempt to identify the discriminatory capability of these parameters. This study aimed to investigate (i) possible differences in rearfoot eversion, hip adduction and knee flexion during stair ascent; (ii) the relationship among peak rearfoot eversion, hip adduction and knee flexion during stair ascent; and (iii) the discriminatory capability of each in individuals with PFP. METHODS Thirty-six females with PFP aged 21.9 (2.72) years and 31 pain-free females aged 22.07 (3.67) years participated. Each participant underwent 3-D kinematic analysis during stair ascent using a 4-camera Vicon motion analysis system. Peak angles for rearfoot eversion, knee flexion and hip adduction were measured using standardized marker sets (Oxford Foot Model combined with Plug-in Gait (SACR)). Betweengroup comparisons were made using analysis of covariance for peak rearfoot eversion, hip adduction and knee flexion, with cadence entered as co-variate. Pearson correlation coefficients were calculated to establish relationship among these parameters, and receiver operating characteristic curves were applied and associated area under the curve (AUC) measures established to identify the discriminatory capability of each parameter. RESULTS Our findings indicate that reduced peak knee flexion (40.0º (3.8) versus 42.6º (3.2), p=0.024), greater peak hip adduction (12.9º (2.0) versus 10.0º (1.3), p=0.000), greater peak rearfoot eversion (5.3º (3.7) versus 3.4º (4.1), p=0.011) and reduced cadence (steps/min) (75.09 (3.72) versus 83.01 (7.87) p=0.035) exist in individuals with PFP during stair ascent. However, peak hip adduction may discriminate those with PFP more effectively than rearfoot eversion and knee flexion (Table 1). Additionally, reduced peak hip adduction was found to significantly correlate with reduced peak knee flexion (r = 0.54 p = 0.002) but not rearfoot eversion (r = -0.08 p = 0.756) in PFP group.
Table 1. Values of sensitivity and specificity for the best balanced cutoff point (degrees) and area under the curve (AUC) values. Variables Rearfoot Eversion Hip Adduction Knee Flexion
Cutoff pointº
Sensitivity %
Specificity %
5.0
58
67
10.6
67
77
42.5
63
45
AUC (95%CI) 0.66 (0.51;0.80) 0.74 (0.60;0.83) 0.57 (0.40;0.74)
pvalue 0.050 0.012* 0.379
Abbreviations: AUC: Area Under the Curve. 95% CI (95% Confidence Interval). * = Statistical significance (p
