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Motor Control of the Knee Kinematic and EMG studies of healthy individuals and people with patellofemoral pain Ann-Katrin Stensdotter
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CONTENT CONTENT ...........................................................................................................4 PAPER I – IV ......................................................................................................5 ABSTRACT .........................................................................................................6 SVENSK SAMMANFATTNING.......................................................................7 ABBREVIATIONS .............................................................................................8 ORIGINAL PAPERS..........................................................................................9 INTRODUCTION.............................................................................................10 The need for evidence based knowledge..........................................................10 Patellofemoral pain.........................................................................................12 Definition of patellofemroal pain ..............................................................12 Prevalence and characteristics..................................................................12 Anatomical features...................................................................................13 Muscle activity...........................................................................................14 Movement strategies ..................................................................................19 Treatment...................................................................................................21 Short muscles and control of joint position ....................................................22 Biomechanical principles of muscle function ............................................22 Anatomy and function of short knee muscles.............................................23 Rationale for this thesis ..................................................................................25 AIMS OF THE THESIS ...................................................................................26 Specific research questions:............................................................................26 METHODS ........................................................................................................27 Subjects ..........................................................................................................27 Study I........................................................................................................27 Study II and III ..........................................................................................27 Study IV .....................................................................................................29 Ethics..............................................................................................................29 Design.............................................................................................................30 Test procedures ..............................................................................................30 Equipment ......................................................................................................34 Electromyography recording.....................................................................34 Electromyography analyses.......................................................................37 Kinematic capture......................................................................................39 Kinematic analysis.....................................................................................41
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Kinetics ......................................................................................................42 Balance perturbation.................................................................................42 Statistical analysis...........................................................................................42 RESULTS...........................................................................................................45 Task specific muscle activity..........................................................................45 Differences between PFP and controls ...........................................................50 Popliteus function...........................................................................................54 DISCUSSION ....................................................................................................57 Results ............................................................................................................57 Task specific muscle activity......................................................................57 Differences between PFP and controls .....................................................60 Methodological considerations.......................................................................66 EMG ..........................................................................................................66 Kinematics .................................................................................................70 Kinetics ......................................................................................................71 Subjects......................................................................................................71 External validity .............................................................................................72 Clinical implications.......................................................................................72 Future research ...............................................................................................74 GENERAL CONCLUSIONS ...........................................................................75 Acknowledgements............................................................................................76 REFERENCES ..................................................................................................78
PAPER I – IV Dissertations written by physiotherapists, Umeå University 1989-2005
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ABSTRACT Motor Control of the Knee
Kinematic and EMG studies of healthy individuals and people with patellofemoral pain ,
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SVENSK SAMMANFATTNING Motorisk kontroll av knäleden
Kinematik och EMG studier av friska individer och individer med patellofemoral smärta ! ) & ** ! B 4 B B + 4 ** ! * B 3, ,8 ' ) 4 & ** & * 4 & * : 4 8
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ASIS Figure 1. The quadriceps angle (Q) is measured between the line drawn from the anterior superior iliac spine (ASIS) through the center of patellae (P) and the line drawn from the tibial tuberosity (T) through P. Q
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Introduction ____________________________________________________
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Introduction ____________________________________________________
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Participants
Dillon et al. (1983) Powers et al. (1997b)
19 PFP 19 controls
Powers et al. (1999a) Salsich et al. (2001)
15 PFP 10 controls 10 PFP 10 controls
Brechter et al. (2002)
10 PFP 10 controls
Anderson & Herrington (2003)
20 PFP 20 controls
Crossley et al. (2004)
48 PFP 18 controls
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Task
Method
Variables
Gait
2-D video
Gait pattern
Ascending and descending stairs, gait Gait
Foot switch, 2-D kinematics, isokinetic dynamometer
Stride, joint angles, isometric knee extensor torque
Reduced walking speed
Force platform, 3-D kinematics
Stride, joint angles
Reduced walking speed
Ascending and descending stairs Ascending and descending stairs Descending stairs
3-D kinematics, inverse dynamics
Cadence; joint angles; joint moments
3-D kinematics, MRI
Cadence; knee kinematics; joint moments; PJRF; patellofemoral joint contact area; patellofemoral joint stress Isokinetic torque curves, knee angular velocity curve
Cadence slower (descent) in PFP; knee extension moments reduced in PFP (ascent and descent) Cadence slower in PFP; PJRF and PJRF-time integral (ascent) less in PFP Break in eccentric torque curve in PFP; break in knee angular velocity curve in PFP;
Ascending and descending stairs
2-D kinematics, isokinetic concentric and eccentric quadriceps sub maximal and maximal torque 2-D kinematic
Results (only sign. Differences reported) Gait pattern
Stance phase knee flexion; heel-strike knee flexion
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Stance phase knee flexion and heel-strike knee flexion was less in PFP
Introduction ____________________________________________________ Treatment :
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Introduction ____________________________________________________
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Figure 10. Twenty spherical reflex markers (19 mm) were placed bilaterally over the 5th metatarsal joint, midpoint of the 3rd metatarsal, lateral malleolus, tibial tuberosity, midpoint of lateral knee joint line, one cm proximal of basis patellae, anterior superior iliac spine, greater trochanter and one cm inferior of acromion. One marker (30 mm) was placed on symphysis of sternum manubrium and one on sacrum between the posterior superior iliac spines (not shown on figure).
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Results ____________________________________________________
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EMG RMS ratio CKC/OKC (of values normalized to MVC)
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VML
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Figure 17. Group means and SEM for ratio of peak RMS EMG amplitude between closed (CKC) and open (OKC) kinetic chain for patellofemoral pain subjects (PFP) [ ] and for controls [ ]. A lower value denotes more activity in OKC. * = p U 8+ ( 3 S > U 8 &9F3 S > U 8 : 4
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Results ____________________________________________________
EMG onset time (ms)
A P
A P
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A P
A P
85 80 75
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PFP Control
65 60 VMO
VML
RF
VL
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Ratio (of vlaues normalized to MVC)
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A P
A P
A P
A P
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PFP
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Control
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VML/VL
VMO/RF
VML/RF
VL/RF
Figure. 19. Group mean differences (SEM) for EMG amplitude ratio between muscle pairs, compared between the PFP group and control group, and between anterior (A) and posterior (P) direction of platform translation. * = p S
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440 Onset time (ms)
420 400 380 360
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VMO
VML
RF
VL
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Results ____________________________________________________
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Results ____________________________________________________ Popliteus function #&$ 9+ ' ! ' !# ' ! ,;, / & 7 ' * < / & # * 4 # &' )* #) * ' & )$ 31:8 & 3,:8 # #! ' * + ,;, ' < ) ! ** # '* ** & ' : ,;, * / &* ! #) & ' 3 S > S 83 / 8 & ' + *$,;, 5%6 / !' ' & ** # '* ?' 6% & ' + ,;, ' < & / ! ' *$ * ' & ** # '* )# 9F 5%6 &!! &) # '* 3 S + > S 8+ & * &!! ) & * 3 S >S 83 / 8 H ** # '* ' & + & * !*# ' & < # # '* &!! *$ 3 ' ! & ' & # '* > S > + S 8 G < + /* ' & ! ' # '* + / !' &!! ' ! 5%6 1: & ,: ?' ! 3 S >S 8 100
Onset time (ms)
90 80 70 60 50
Anterior Posterior
40 0 VMO
RF
VL
POP
GM
BF
TA
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