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Brunnstrom’s Clinical Kinesiology Sixth Edition CHAPTER 10 Knee Copyright © 2012 F.A. Davis Company Brunnstrom’s Clinical Kinesiology Sixth Edition Introduction Is the largest joint in body; frequently injured because it is positioned between two long bony levers Copyright © 2012 F.A. Davis Company Brunnstrom’s Clinical Kinesiology Sixth Edition Bones Femur Tibia Tibial tuberosity Fibula Copyright © 2012 F.A. Davis Company Brunnstrom’s Clinical Kinesiology Sixth Edition Patella Bones Largest sesamoid bone in body Multiple functions: Increase internal moment arm of quadriceps Centralize force of quadriceps pull Reduce tendon and friction forces Contribute to overall knee stability Provide bony protection Copyright © 2012 F.A. Davis Company Brunnstrom’s Clinical Kinesiology Sixth Edition Joints Tibiofemoral (knee) Largest joint in body Hinge/ginglymus “trocho-ginglymus”? Copyright © 2012 F.A. Davis Company Brunnstrom’s Clinical Kinesiology Sixth Edition Joints Tibiofemoral—menisci Wedge shaped—thickest toward outer rim Move anteriorly with knee extension, posteriorly with knee flexion Functions: Deepen socket and improve congruency Absorb and distribute forces/increase surface area Copyright © 2012 F.A. Davis Company Brunnstrom’s Clinical Kinesiology Sixth Edition Joints Tibiofemoral—menisci Functions: Promote lubrication of joint Prevent joint capsule from intruding into joint space Partially protect against excessive motion Copyright © 2012 F.A. Davis Company Brunnstrom’s Clinical Kinesiology Sixth Edition Joints Tibiofemoral—collateral ligaments Origins are offset superiorly and posteriorly Causes the collaterals to tighten with knee extension Copyright © 2012 F.A. Davis Company Brunnstrom’s Clinical Kinesiology Sixth Edition Joints Tibiofemoral—collateral ligaments Lateral collateral ligament Has distinct structure—rope- or cord-like Is located outside of joint capsule—”extracapsular” Provides primary restraint when the knee is subjected to laterally directed forces Copyright © 2012 F.A. Davis Company Brunnstrom’s Clinical Kinesiology Sixth Edition Joints Tibiofemoral—cruciate ligaments Intracapsular; extrasynovial Named by appearance of “cross” they create Maintain near same length throughout range of motion (ROM) Copyright © 2012 F.A. Davis Company Brunnstrom’s Clinical Kinesiology Sixth Edition Joints Tibiofemoral—cruciate ligaments Anterior cruciate Anterior medial–posterior lateral bundles Resists anterior translation of tibia on femur Posterior cruciate Anterior lateral–posterior medial bundles Resists posterior translation of tibia on femur Copyright © 2012 F.A. Davis Company Brunnstrom’s Clinical Kinesiology Sixth Edition Joints Tibiofemoral—osteokinematics (sagittal) Flexion On average, to 135° Limited by soft tissue approximation Extension To 0°; often hyperextends but not past 15° Limited by capsular tightening Copyright © 2012 F.A. Davis Company Brunnstrom’s Clinical Kinesiology Sixth Edition Joints Tibiofemoral—osteokinematics (transverse) Axial rotation Occurs when knee is flexed At 90° of flexion, 45° total (2:1; lateral:medial) Occurs about a vertical or longitudinal axis Normal end feels are firm—capsular Copyright © 2012 F.A. Davis Company Brunnstrom’s Clinical Kinesiology Sixth Edition Joints Patellofemoral—Q angle Females > Q angle compared with males Genu varum—valgum Copyright © 2012 F.A. Davis Company Brunnstrom’s Clinical Kinesiology Sixth Edition Muscles Knee extensors Quadriceps femoris Vastus lateralis Vastus medialis oblique and vastus medialis longus Vastus intermedius Rectus femoris Copyright © 2012 F.A. Davis Company Brunnstrom’s Clinical Kinesiology Sixth Edition Muscles Knee flexors Hamstrings Gastrocnemius—plantaris—popliteus Gracilis Sartorius Copyright © 2012 F.A. Davis Company Brunnstrom’s Clinical Kinesiology Sixth Edition Functions of Knee Muscles Knee extensors Function to: Stabilize—isometric Decelerate—eccentric Accelerate—concentric Large and powerful muscle group Necessary to match demands of ADLs and recreational activities Copyright © 2012 F.A. Davis Company Brunnstrom’s Clinical Kinesiology Sixth Edition Functions of Knee Muscles Knee extensors Rectus femoris Biarticular muscle crossing both hip and knee Vastus medialis VMO—fiber direction: 50–55°; stabilize patella VML—fiber direction: 15–18° Copyright © 2012 F.A. Davis Company Brunnstrom’s Clinical Kinesiology Sixth Edition Functions of Knee Muscles Knee flexors Hamstrings Little force required by these muscles in open chain Closed chain—great forces required particularly at hip Dynamically restrain anterior tibial translation Function to assist and decelerate rotation Copyright © 2012 F.A. Davis Company Brunnstrom’s Clinical Kinesiology Sixth Edition Functions of Knee Muscles One and two joint muscles acting at the knee Majority of muscles that cross knee are biarticular. Multijoint muscles: Are more efficient Produce motion in multiple planes Seldom act at both joints simultaneously Copyright © 2012 F.A. Davis Company Brunnstrom’s Clinical Kinesiology Sixth Edition Functions of Knee Muscles One and two joint muscles acting at the knee Knee flexion with hip extension Hamstrings—active insufficiency Rectus femoris—passive insufficiency Knee extension with hip flexion Hamstrings—passive insufficiency Rectus femoris—active insufficiency Copyright © 2012 F.A. Davis Company Brunnstrom’s Clinical Kinesiology Sixth Edition Functions of Knee Muscles One and two joint muscles acting at the knee Knee flexion with hip flexion Hamstrings—elongated at hip; shortened at knee Rectus femoris—elongated at knee; shortened at hip Knee extension with hip extension Hamstrings—elongated at knee; shortened at hip Rectus femoris—elongated at hip; shortened at knee Copyright © 2012 F.A. Davis Company Brunnstrom’s Clinical Kinesiology Sixth Edition Joint Forces Tibiofemoral Forces across joint increase with activity. Shear stresses (A-P) are also experienced with knee range. Anterior cruciate ligament (ACL) and hamstrings restrict anterior tibial translation. Posterior cruciate ligament (PCL) and quadriceps restrict posterior tibial translation. Excessive forces over time may promote degenerative joint disease. Copyright © 2012 F.A. Davis Company Brunnstrom’s Clinical Kinesiology Sixth Edition Joint Forces Torque of muscles acting at knee Hamstring/quadriceps ratio Established with isokinetic dynamometry Typically quantified at 60°/second during a concentric contraction of both muscle groups Normal ratio—2:3, or 66% Copyright © 2012 F.A. Davis Company