A clinical study of the biomechanics of step descent using 3 treatment modalities for patellofemoral pain

Abstract

INTRODUCTION:
Previous studies have demonstrated that patellofemoral bracing and taping have significant effects on the coronal and torsional mechanics of the knee in both healthy subjects1 and in patients with patellofemoral pain syndrome (PFPS)2 and lead to a more controlled eccentric step descent. It is likely that some of the observed effects are due to enhanced proprioception mediated through increased cutaneous stimulation. To investigate this further, we recruited PFPS patients for 2 studies with identical methodologies, the combined results of which are presented here. Study A investigated the effect of bracing and taping; study B investigated the effect of Tubigrip and taping. To our knowledge, this is the first study to investigate the effect of a simple elasticated tubular bandage on the 3-D mechanics of the knee during a controlled eccentric step-down task in a group of patients with PFPS.

METHODS:
Twenty-nine subjects with a diagnosis of PFPS (13 men, 16 women) with a mean age of 31 years were recruited (Modified Functional Index Questionnaire score, 24; visual analog scale for usual pain in the past week, 31 mm). Inclusion criteria were presence of traumatic or idiopathic peripatellar pain and pain provoked by deep squatting, kneeling, ascending, or descending stairs, alone or in combination. The exclusion criterion was any history of knee surgery. A step descent was used to assess the control of the knee as the body was lowered as slowly as possible from the step. The step descent was conducted under 4 randomized conditions over the 2 studies: (a) no intervention, (b) Tru-Pull Advanced sleeve knee brace (DJO, LLC, Vista, CA), (c) neutral patella taping, and (d) elasticated tubular bandage (Tubigrip; Mӧlnlycke Health Care, Norcross, GA). For the application of the taping technique, the subjects were sitting with a relaxed, extended knee. One strip of tape of a length equal to 50% of the circumference of the knee was applied without tension across the center of the patella. The tape was not pulled in either the medial or lateral direction. A length of Tubigrip equal to the circumference of the knee was applied. Kinetic data were collected at 200 Hz using 2 AMTI force platforms. A 20-cm step was built on top of 1 of the plates, which was set to 0 prior to data collection. The other plate was embedded in the floor. Kinematic data were collected using a 10-camera Oqus motion-analysis system (Qualisys Medical AB, Gothenburg, Sweden) at 100 Hz. The segments of the lower limbs were modeled in 6 degrees of freedom. 3 The knee joint kinematics were calculated relative to the shank coordinate system. The kinematic data were then quantified from toe-off of the contralateral limb to contact of the contralateral limb. The ranges of knee joint angle in the sagittal, coronal, and transverse planes were found.

RESULTS:
An ANOVA identified significant changes in the knee range of motion. Post hoc analyses are presented in the TABLE. No significant differences were identified in the sagittal plane.

DISCUSSION:
Changes were identified in the coronal and transverse plane kinematics of the knee joint between no intervention and bracing, taping, and Tubigrip. Taping and Tubigrip resulted in similar changes in the joint mechanics of the knee in the coronal plane only, whereas the brace produced changes in both the coronal and transverse planes. The results of taping and Tubigrip are interesting, as there was a measurable reduction in coronal plane ROM following these interventions, which do not apply significant mechanical forces to the knee. These data lend support to the argument that these interventions produce subtle yet important improvements in patient control and function and that the observed effects are probably linked to enhanced proprioception. The brace, compared to the other interventions, resulted in significant reductions in ROM in both the coronal and transverse planes. This suggests the brace does have a mechanical effect, which is additional to any proprioceptive effects. The effect of the brace was greater than that of both tape and Tubigrip, but all 3 treatments appear to result in a step descent, which was more controlled compared to no intervention in this group of patients with PFPS.
ACKNOWLEDGEMENTS:
DJO, LLC supplied the Tru-Pull Advanced sleeve knee braces. They played no role in the design, analysis, or interpretation of the study and its findings.