The Knee Joint • Knee joint – largest joint in body Chapter 10 – very complex The Knee Joint – primarily a hinge joint Manual of Structural Kinesiology Modified for Prentice WE: Arnheim’s principles of athletic training , ed 12, New R.T. Floyd, EdD, ATC, CSCS York, 2006, McGraw-Hill; from Saladin, KS: Anatomy &physiology: the unity of forms and function , ed 2, New York, 2001, McGraw- Hill. © 2007 McGraw-Hill Higher Education. All rights reserved. 10-1 © 2007 McGraw-Hill Higher Education. All rights reserved. 10-2 Bones Bones • Enlarged femoral condyles articulate on • Fibula - lateral enlarged tibial condyles – serves as the attachment for • Medial & lateral tibial condyles (medial & knee joint lateral tibial plateaus) - receptacles for structures femoral condyles – does not articulate • Tibia – medial with femur or patella – bears most of weight – not part of knee joint Modified from Anthony CP, Kolthoff NJ: Textbook of anatomy and physiology , ed 9, St. Louis, 1975, Mosby. © 2007 McGraw-Hill Higher Education. All rights reserved. 10-3 © 2007 McGraw-Hill Higher Education. All rights reserved. 10-4 Bones Bones • Patella • Key bony landmarks – sesamoid (floating) bone – Superior & inferior patellar poles – imbedded in quadriceps – Tibial tuberosity & patellar tendon – Gerdy’s tubercle – serves similar to a pulley – Medial & lateral femoral in improving angle of condyles pull, resulting in greater – Upper anterior medial tibial mechanical advantage in surface – Head of fibula knee extension Modified from Anthony CP, Kolthoff NJ: Textbook of anatomy and physiology , ed 9, St. Louis, 1975, Mosby. © 2007 McGraw-Hill Higher Education. All rights reserved. 10-5 © 2007 McGraw-Hill Higher Education. All rights reserved. 10-6 1 Bones Bones • Three vasti muscles of quadriceps originate • Semimembranosus inserts posteromedially on on proximal femur & insert on patellar medial tibial condyle superior pole • Biceps femoris inserts primarily on fibula head – insertion is ultimately on tibial tuberosity via • Popliteus originates on lateral aspect of lateral patella tendon femoral condyle • Iliotibial tract of tensor fasciae latae inserts • Tibial collateral ligament originates on medial on Gerdy’s tubercle aspect of upper medial femoral condyle & inserts on medial tibial surface • Sartorius, gracilis, & semitendinosus insert just below the medial condyle on upper • Fibula collateral originates on lateral femoral condyle very close to popliteus origin & inserts anteromedial tibial surface on fibular head © 2007 McGraw-Hill Higher Education. All rights reserved. 10-7 © 2007 McGraw-Hill Higher Education. All rights reserved. 10-8 Joints Joints • Knee joint proper (tibiofemoral joint) • Ligaments provide static stability – classified as a ginglymus joint • Quadriceps & hamstrings contractions produce • Sometimes referred to as trochoginglymus dynamic stability joint internal & external rotation occur during • Articular cartilage surfaces on femur & tibia flexion • Some argue for condyloid classification • Menisci form cushions between bones • Patellofemoral joint – attached to tibia – arthrodial classification – deepen tibial fossa – gliding nature of patella on femoral – enhance stability condyles © 2007 McGraw-Hill Higher Education. All rights reserved. 10-9 © 2007 McGraw-Hill Higher Education. All rights reserved. Modified from Anthony CP, Kolthoff NJ: Textbook of anatomy and 10-10 physiology , ed 9, St. Louis, 1975, Mosby. Joints Joints • Medial meniscus forms receptacle for medial – Either or both menisci may be torn in femoral condyle, Lateral meniscus receives several different areas from a variety lateral femoral condyle of mechanisms, resulting in varying – Thicker on outside border & taper down very thin degrees of problems to inside border – Can slip about slightly, but held in place by • Tears often occur due significant various small ligaments compression & shear forces during – Medial meniscus - larger & more open C rotation while flexing or extending appearance during quick directional changes in – Lateral meniscus - closed C configuration running © 2007 McGraw-Hill Higher Education. All rights reserved. 10-11 © 2007 McGraw-Hill Higher Education. All rights reserved. 10-12 2 Joints Joints • Anterior & posterior cruciate ligaments • Posterior cruciate – cross within knee between tibia & femur ligament (PCL) injuries – vital in respectively maintaining anterior & – not often injured posterior stability, as well as rotatory stability – mechanism of direct • Anterior cruciate ligament (ACL) injuries contact with an opponent – one of most common serious injuries to knee or playing surface – mechanism often involves noncontact rotary • Fibular (lateral) forces associated with planting & cutting, collateral ligament (LCL) hyperextension, or by violent quadriceps – infrequently injured Modified from Anthony CP, Kolthoff NJ: Textbook of anatomy and contraction which pulls tibia forward on femur physiology , ed 9, St. Louis, 1975, Mosby. © 2007 McGraw-Hill Higher Education. All rights reserved. 10-13 © 2007 McGraw-Hill Higher Education. All rights reserved. 10-14 Joints Joints • Tibial (medial) collateral ligament (MCL) • Synovial cavity – maintains medial stability by resisting – supplies knee with synovial fluid – lies under patella and between surfaces of tibia & valgus forces or preventing knee from femur being abducted – "capsule of the knee” – injuries occur commonly, particularly in • Infrapatellar fat pad contact or collision sports – just posterior to patellar tendon – mechanism of teammate or opponent may – an insertion point for synovial folds of tissue fall against lateral aspect of knee or leg known as “plica” • an anatomical variant that may be irritated or causing medial opening of knee joint & inflamed with injuries or overuse of the knee stress to medial ligamentous structures © 2007 McGraw-Hill Higher Education. All rights reserved. 10-15 © 2007 McGraw-Hill Higher Education. All rights reserved. 10-16 Joints Joints • Bursae • Extends to 180 degrees (0 – more than 10 degrees of flexion) bursae in & • Hyperextension of 10 degrees or around knee > not uncommon – some are • Flexion occurs to about 140 connected to degrees synovial cavity – they absorb • With knee flexed 30 degrees or > shock or prevent – internal rotation 30 degrees occurs friction – external rotation 45 degrees occurs © 2007 McGraw-Hill Higher Education. All rights reserved. 10-17 © 2007 McGraw-Hill Higher Education. All rights reserved. 10-18 3 Joints Movements • Knee “screws home” to fully extend due to the • Flexion shape of medial femoral condyle – As knee approaches full extension tibia must – bending or decreasing externally rotate approximately 10 degrees to angle between femur & achieve proper alignment of tibial & femoral leg, characterized by heel condyles moving toward buttocks – In full extension • close congruency of articular surfaces • Extension • no appreciable rotation of knee – straightening or – During initial flexion from full extension increasing angle between • knee “unlocks” by tibia rotating internally, to a femur & lower leg degree, from its externally rotated position to achieve flexion © 2007 McGraw-Hill Higher Education. All rights reserved. 10-19 © 2007 McGraw-Hill Higher Education. All rights reserved. 10-20 Movements Muscles • Quadriceps muscle group • External rotation – extends knee – rotary movement of leg – located in anterior laterally away from midline compartment of thigh • Internal rotation – consists of 4 muscles – rotary movement of lower • rectus femoris leg medially toward midline • vastus lateralis • Neither will occur unless • vastus intermedius • vastus medialis flexed 20-30 degrees or > © 2007 McGraw-Hill Higher Education. All rights reserved. 10-21 © 2007 McGraw-Hill Higher Education. All rights reserved. 10-22 Muscles Muscles • Q angle • Q angle – Central line of pull for entire – Higher Q angles generally quadriceps runs from ASIS to the predispose people in varying center of patella degrees to a variety of potential – Line of pull of patella tendon runs knee problems including lateral from center of patella to center of patellar subluxation or dislocation, tibial tuberosity patellar compression syndrome, – Angle formed by the intersection of chondromalacia, and ligamentous these two lines at the patella is the injuries Q angle – For people with above normal Q angles, it is particularly important – Normally, angle will be 15 degrees to maintain high levels of strength or less for males & 20 degrees or & endurance in vastus medialis so less in females as to counteract lateral pull of – Generally, females have higher vastus lateralis angles due to a wider pelvis © 2007 McGraw-Hill Higher Education. All rights reserved. 10-23 © 2007 McGraw-Hill Higher Education. All rights reserved. 10-24 4 Muscles Muscles • Hamstring muscle group • Two-joint muscles – responsible for knee flexion – most effective when either origin or – located in posterior compartment of thigh insertion is stabilized to prevent movement – consists of 3 muscles in direction of the contacting muscle • semitendinosus - medial, internal rotator – To a degree, muscles are able to exert • semimembranosus - medial, internal rotator greater force when lengthened than when • biceps femoris - lateral, external rotator shortened • Popliteus assist medial hamstrings in – Hamstring muscles & rectus femoris are biarticular (two-joint) muscles knee internal rotation © 2007 McGraw-Hill Higher Education. All rights reserved. 10-25 © 2007 McGraw-Hill