Article

Increased patellofemoral joint (PFJ) stress has been implicated in the
development of PFJ pathologies. Previous studies have identified a relationship
between reduced hamstring length and patellofemoral pain syndrome. Hamstring
stretching is also recommended in the management thereof. However, the
relationship between reduced hamstring length and PFJ stress has not been
explored in vivo during activities that load the PFJ, such as squatting. The
objective of this study was to determine if persons with reduced hamstring length
demonstrate increased PFJ stress during squatting compared with individuals
without reduced hamstring length. Eight participants with, and eight participants
without, reduced hamstring length were assessed to determine their PFJ contact
area using magnetic resonance imaging, and their PFJ reaction force during
squatting using motion analysis. Data collected were entered into a biomechanical
model to calculate medial, lateral and total PFJ stress. It was found that
participants with reduced hamstring length had significantly greater total
(393.39 Pa/kg vs. 213.01 Pa/kg) and lateral (311.23 Pa/kg vs. 142.55 Pa/kg) PFJ
stress at 60 degrees knee flexion during squat descent and ascent (427.75 Pa/kg
vs. 255.64 Pa/kg and 337.75 Pa/kg vs. 170.63 Pa/kg, respectively). This was due
to significantly increased PFJ reaction force at 60 degrees knee flexion during
squat descent (12.18 N/kg vs. 7.21 N/kg) and ascent (13.03 N/kg vs. 8.72 N/kg),
and lower medial PFJ contact area at 60 degrees knee flexion (88 mm(2) vs. 160
mm(2)). The results of this study demonstrate a relationship between reduced
hamstring length and increased PFJ stress during squatting due to increased PFJ
reaction force and reduced medial PFJ contact area.
CI - Copyright 2009 Elsevier B.V. All rights reserved.

Langue : ANGLAIS