VASTUS MEDIALIS OBLIQUE – VASTUS LATERALIS MUSCLE IMBALANCE IN PATELLOFEMORAL PAIN SYNDROME (PFPS) PATIENTS A thesis submitted to the University of Manchester for the degree of the Doctor of Philosophy in the Faculty of Medical & Human Sciences 2013 Panagiotis Nikolaos Trigkas School of Medicine List of Contents Page 1 Title page 2 List of contents 3 Table of contents 8 Table of tables 15 Table of figures 16 Abstract 17 Declaration of Authorship and Copyright 18 Acknowledgements 19 Dedication 20 The Text ii Table of Contents 1. INTRODUCTION ............................................................................................................. 2 1.1. PATELLAR TRACKING AND PATELLOFEMORAL PAIN ............................................................. 4 1.2. QUADRICEPS FEMORIS MUSCULAR DYSFUNCTION AND PATELLAR TRACKING ........................ 5 1.3. PHYSIOTHERAPY TREATMENT FOR PFPS ............................................................................. 6 2. THE PATELLOFEMORAL JOINT ....................................................................................... 9 2.1. ANATOMY OF THE PATELLOFEMORAL JOINT ....................................................................... 9 2.1.1. The patella and the femoral trochlea .......................................................... 9 2.2. ANATOMY OF THE QUADRICEPS FEMORIS MUSCLE ........................................................... 11 2.2.1. Anatomy of Vastus Medialis and Vastus Lateralis ...................................... 13 2.3 PHYLOGENETICAL EVOLUTION OF THE VASTUS MEDIALIS AND VASTUS LATERALIS ................ 18 2.4 BIOMECHANICS ............................................................................................................. 18 2.4. 1 Patellofemoral joint reaction forces ............................................................ 19 2.4. 2 Patellofemoral joint contact areas ............................................................ 21 2.4. 3 Quadriceps angle – Q angle ....................................................................... 22 3. PATELLOFEMORAL PAIN SYNDROME ......................................................................... 26 3.1 NOMENCLATURE............................................................................................................ 26 3.2 PREVALENCE & CHARACTERISTICS ................................................................................... 27 3.3 CONTRIBUTING FACTORS OF PFPS AETIOPATHOGENESIS ................................................... 30 3.3.1 Muscular Dysfunction .................................................................................... 31 3.3.2 Structural and Postural Alterations of the Lower Extremity ......................... 38 4. BACKGROUND LITERATURE REVIEW ........................................................................... 42 4.1.1 Review Search Strategy ................................................................................ 42 4.1.2 DETERMINING THE QUALITY OF THE PAPERS REVIEWED ............................... 43 4.1.3 IMPLICATIONS OF THE MODIFICATION OF THE QUALITY SCALE .................. 46 4. 1. 4 INTRARRATER RELIABILITY OF THE QUALITY RATING .................................... 47 4.2 STUDIES IN RELATION TO VMO-VL AMPLITUDE & RATIO IN PFPS PATIENTS .......................... 48 4. 2.1 STUDIES IN FAVOUR OF VMO-VL AMPLITUDE & RATIO MUSCLE IMBALANCE IN PFPS PATIENTS ..................................................................................................... 48 iii 4.2.2 STUDIES NOT IN FAVOUR OF VMO-VL AMPLITUDE & RATIO MUSCLE IMBALANCE IN PFPS PATIENTS ................................................................................ 54 4.2. STUDIES IN RELATION TO VMO – VL ONSET TIME & REFLEX RESPONSE IN PFPS .................. 63 PATIENTS ............................................................................................................................. 63 4.2.1 STUDIES IN FAVOUR OF VMO-VL ONSET TIME & REFLEX RESPONSE MUSCLE IMBALANCE IN PFPS PATIENTS ................................................................................ 63 3.3.2 STUDIES NOT IN FAVOUR OF VMO-VL TIME ONSET & REFLEX RESPONSE MUSCLE IMBALANCE IN PFPS PATIENTS ................................................................. 69 IMBALANCE IN PFPS PATIENTS ............................................................................................... 74 4.4.1 STUDIES IN FAVOUR OF VMO-VL FATIGUE CHARACTERISTICS MUSCLE IMBALANCE IN PFPS PATIENTS ................................................................................ 74 4.4 DOES THE VMO – VL MUSCLE IMBALANCE EXIST? ........................................................... 76 4.4.1 METHODOLOGY ............................................................................................. 77 4.4.2 MEASURES AND CLINICAL SIGNIFICANCE .................................................... 81 4.4.3 SAMPLE SIZE & HOMOGENEITY ..................................................................... 83 4.4.4 ANATOMICAL AND BIOMECHANICAL CHARACTERISTICS .......................... 85 4.4.5 Summary ........................................................................................................ 86 5. OVERVIEW OF THE QUADRICEPS FEMORIS MUSCULAR PERFORMANCE OF THE HEALTHY POPULATION ................................................................................................... 88 5.1 INTRODUCTION .............................................................................................................. 88 5.2 RESULTS OF THE CONTROL HEALTHY SUBJECTS OF THE REVIEWED PFPS STUDIES 94 5.3 DOES THE VMO-VL MUSCLE IMBALANCE ALSO EXIST IN THE HEALTHY POPULATION? ................................................................................................................. 97 6. AIM – HYPOTHESIS – OBJECTIVES – EXPERIMENTAL DESIGN .................................. 103 6.1 AIM OF THE STUDY ................................................................................................... 103 6.2 OBJECTIVES: ............................................................................................................ 103 6.3 NULL HYPOTHESES TO TEST OBJECTIVE 1: .............................................................. 104 6.3.1 PLAN OF INVESTIGATIONS & PROCEDURES ................................................ 104 6.3.2 EXPERIMENTAL DESIGN TO TEST OBJECTIVE 1 ............................................. 107 6.4 NULL HYPOTHESES TO TEST OBJECTIVE 2 ............................................................... 117 6.4.1 EXPERIMENTAL DESIGN TO TEST OBJECTIVE 2 ............................................. 117 iv 6.5 NULL HYPOTHESES TO TEST OBJECTIVE 3 ............................................................... 128 6.5.1 EXPERIMENTAL DESIGN TO TEST OBJECTIVE 3 ............................................. 128 7. STUDY I: MEASURES OF MUSCLE FUNCTION ............................................................ 133 7.1 DESCRIPTIVE STATISTICS OF THE SUBJECTS ....................................................................... 133 7.2 OVERALL MUSCULAR PERFORMANCE ANALYSIS .............................................................. 133 7.3 OVERALL MUSCULAR PERFORMANCE ANALYSIS BY TASK .................................................. 137 7.3.1 Functional tasks ........................................................................................... 137 7.3.2 Experimental tasks ....................................................................................... 154 8. STUDY II: MEASURES OF CLINICAL SYMPTOMS ........................................................ 163 8.1 ASSESSMENT OF PAIN AND FUNCTION ............................................................................ 163 8.1.1 Overall assessment of pain, duration of symptoms and function ........... 163 8.1.2 Correlations of the pain level with measures of muscle function ............ 166 8.1.3 Correlations of the duration of symptoms with measures of muscle function ................................................................................................................. 172 8.1.4 Correlations of the Anterior Knee Pain Scale (AKPS) score with measures of muscle function ................................................................................................ 175 8.2 ASSESSMENT OF MUSCULAR FLEXIBILITY ........................................................................... 180 8.3 ASSESSMENT OF BIOMECHANICAL CHARACTERISTICS ...................................................... 183 9. STUDY III: REPETETIVE LOAD TASKS ........................................................................... 186 9.1 OVERALL MUSCULAR ANALYSIS PERFORMANCE OF THE REPETITIVE LOADS TASK .................. 186 9.1.1 Time onset differences ................................................................................ 186 9.1.2. VMO & VL normalised EMG RMS amplitude ............................................ 188 10. DISCUSSION ............................................................................................................ 191 10.1 NOVELTY CHARACTERISTICS ........................................................................................ 191 10.2 SYNOPSIS OF THE FINDINGS ......................................................................................... 192 10.3 CLINICAL IMPLICATIONS OF THE FINDINGS .................................................................... 195 10.4 LIMITATIONS OF THE STUDY & RECOMMENDATIONS FOR FUTURE RESEARCH ...................... 200 10.5 CONCLUSIONS .........................................................................................................