ChiroCredit.com Presents Biomechanics: Focus on the Knee Presented by: Ivo Waerlop, DC Shawn Allen, DC 1 Focus on The Knee 2 Pertinent Anatomy Femur Tibia Fibula Patella Prepatellar bursa Infrapatellar bursa Patellar retinaculum lateral/medial Capsule LCL MCL 3 1
Femur Femoral condyles Tibia Tibial Plateau Pertinent Anatomy Fibular head Oblique poplitealligament Arcuate popliteal ligament LCL MCL Semimembranosis bursa Gastroc bursae 4 Lateral Medial 5 Muscle review 6 2
posterior medial 7 Knee Articulation Hinge or gingylmus Diarthrodial Between 2 ball and socket joints Has largest sesamoid bone 8 Polling Question #1 9 3
Gait Cycle Review 10 Movements of the knee in the transverse (axial) plane Medial rotation Also called medial or internal spin Lateral rotation Also called lateral or external spin 11 What happens to the knee during pronation Pronation causes medial rotation of leg and thigh This is due to flexion, adduction and eversion of talus Pronation causes medial rotation of the knee 12 4
Medial condyle larger than lateral Allows a greater range of movement Think about if movement is open or closed chain In closed chain, femur rotates internally from initial contact to midstance Rotates externally from midstance to toe off 13 Pronation R short video 14 What happens to the knee during supination Supination causes external rotation of lower leg and thigh Supination causes external rotation of the knee 15 5
What happens to the knee during supination Initiated by opposite foot going into swing femur externally rotates tibia externally rotates 16 Medial condyle larger than lateral Allows a greater range of movement Think about if movement is open or closed chain In closed chain, femur rotates internally from initial contact to midstance Rotates externally from midstance to toe off 17 supination R short video 18 6
Knee during gait cycle Internal rotation External rotation 19 Polling Question #2 20 Saggital plane movement 21 7
Knee during gait cycle extension flexion extension flexion 22 Vertical oscillation Knee flexion dampens vertical oscillation of pelvis 23 Saggital plane movement Lack vert video Incr flexion video 24 8
Factors altering knee position in the transverse (axial) plane Tibial torsions Femoral torsions Subtalar versions 25 Angle between proximal and distal tibia Goes from 0 in infant to 22 degrees in adult Tibial Torsion 26 27 9
Tibial Torsion Internal torsion External torsion 28 Femoral Torsions 29 Femoral angles Proximal femur Superior view Distal femur Inferior view 30 10
Femoral Development Angle between neck and condyles reduces from 60 degrees in infant to 18 degrees in adult We are born anteverted 31 Femoral angle > 25 degrees Increased ROM: internal rotation of femur Limited external rotation of femur Knee often rotated in when standing Ante torsion 32 Femoral Antetorsion 33 11
Femoral head angle < 8 degrees Increased ROM: external rotation of femur Decreased internal rotation of femur Knee often rotated out when viewed standing Retro torsion 34 Femoral Retro Torsion 35 Look at tibial tuberosity and foot position If lined up, probably no tibial torsion and malposition due to femoral torsion Hint on torsions Tibial tuberosity Foot position 36 12
Look at tibial tuberosity and foot Hint on torsions If NOT lined up, probably looking at tibial torsion Tibial tuberosity Foot Position 37? 38 Angle between talar dome and neck reduces from 30 degrees adduction at birth to 18 degrees in adulthood Subtalar angle 39 13
40 Axial deviations coronal shift 41 Factors altering knee position in the frontal (coronal) plane Tibial varum Genu varum Gevu valgum 42 14
Tibial varum This is how much bend (bowing) there is in the tibia. 43 Tibial and Genu Varum Increased varum will require the foot to pronate through a greater range of motion in a shorter interval of time. The foot will often remain in supination 44 a lateral curvature of the knee in the frontal plane Bow legged Refers to the knee, rather than the tibia Genu Varum 45 15
Genu Varus Varus forces increase tensile forces laterally (LCL, VL, TFL) and compressive forces medially on the medial meniscus and medial condyle/plateau. The greater the varus angle, the more the foot needs to pronate to come into contact with the ground. These folks usually have patellar tracking problems because of the increased internal rotation of the knee. 46 Genu Valgus knock kneed the Q angle is normally 8 12 When the angle exceeds 12, genu valgus exists 47 Genu Valgus Valgus forces generally increase tensile forces at the medial aspect of the knee (MCL, VMO, adductors, sartorius) and compressive forces on the lateral condyle, tibial plateau and meniscus. The greater the valgus angle, the more the foot needs to supinate (its already in pronation). 48 16
coronal deviation Coronal shift Rf genu valgus long Tib varum 49 Factors causing heel lift A. Forward momentum of body B. Passive tension in posterior compartment C. Active contraction of gastroc soleus group D. Windlass effect of plantar fascia 50 Windlass effect of plantar fascia 51 17
Asymmetrical pull on plantar fascia assists in supination 52 18