Chapter 10 the Knee Joint

Home , Tibia, Vastus lateralis muscle, Vastus medialis

• 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.

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.

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.

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

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

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.

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

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

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 >

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

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

Muscles Muscles • Ex. sartorius muscle • Gracilis, sartorius, & semitendinosus join – increases its total length & becomes a together distally to form pes anserinus better flexor at knee when pelvis is rotated – attaches to anteromedial aspect of proximal tibia posteriorly & stabilized by abdominal below the level of tibial tuberosity muscles – Their attachment & posteromedially line of pull • exemplified by trying to flex knee & cross the enable them to assist with knee flexion particularly legs in the sitting position once the knee is flexed & hip is externally rotated • one usually leans backward to flex legs at • Medial & lateral gastrocnemius heads attach knees posteriorly on medial & lateral femoral – Football kicker invariably leans well condyles backward to raise & fix the rectus femoris – assist with knee flexion origin to make it more effective as a knee extensor

Muscles Muscles Knee joint muscles location Knee joint muscles location • Anterior - primarily knee • Posterior - primarily knee flexion extension – Biceps femoris – Rectus femoris – Semimembranosus – Vastus medialis – Semitendinosus – Vastus intermedius • Sartorius – Vastus lateralis • Gracilis • Popliteus • Gastrocnemius

5 Nerves Nerves • Femoral nerves • Sciatic nerve innervates the knee – tibial division extensors (quadriceps) • semitendinosus, – rectus femoris semimembranosus, biceps femoris (long – vastus medialis head) – vastus intermedius – common peroneal – vastus lateralis (fibular) division • biceps femoris (short head)

Quadriceps Muscles Quadriceps Muscles • Quadriceps muscles - vital in jumping • Rectus femoris (two-joint), vastus medialis, – functions as a decelerator vastus intermedius, vastus lateralis (largest) • when decreasing speed to change direction • All attach to patella then to tibial tuberosity via patellar tendon • when coming down from a jump • All superficial & palpable except vastus – eccentric contraction during decelerating intermedius (under rectus femoris) actions • Strength or power may be indicated by vertical – controls slowing of movements initiated in jump test previous phases of the sports skill • Generally desired to be 25% to 33% stronger than hamstring group

Quadriceps Muscles Rectus Femoris Muscle

• Strength & endurance is essential for maintenance of patellofemoral stability

– often a problem Flexion of hip – quads are particularly prone to atrophy when injuries occur Extension of – may be developed by resisted knee knee extension activities from a seated position Anterior pelvic – functional weight bearing activities such as rotation step-ups or squats are particularly useful for strengthening & endurance

6 Vastus Lateralis Muscle Vastus Intermedius Muscle

Extension of Extension of knee knee

Vastus Medialis Muscle Hamstring Muscles

• Hamstring muscle group – Semitendinosus Extension of – Biceps femoris knee – Semimembranosus

Hamstring Muscles Semitendinosus Muscle

• Hamstring muscle strains very common Flexion of knee • “Running muscles” function in acceleration Extension of hip • Antagonists to quadriceps muscles at knee Internal rotation of • Named for cordlike attachments at knee hip • All originate on ischial tuberosity of pelvis Internal • Semitendinosus inserts on anteromedial tibia rotation of flexed knee • Semimembranosus inserts on posteromedial Posterior pelvic tibia rotation • Biceps femoris inserts on lateral tibial condyle & head of fibula

7 Semimembranosus Muscle Biceps Femoris Muscle

Flexion of knee Flexion of knee Extension of hip Extension of hip Internal rotation External of hip rotation Internal rotation of hip of flexed External knee rotation of flexed Posterior pelvic knee rotation Posterior pelvic rotation

Popliteus Muscle Knee Extension Flexion of knee • Agonists – Rectus Femoris Internal rotation of – Vastus Lateralis flexed knee – Vastus Intermedius – Vastus Medialis

Knee Flexion Knee Internal Rotation • Agonists – Biceps Femoris • Agonists (Long & Short – Semitendinosus Head) – Semimembranosus – Semitendinosus – Popliteus – Semimembranosus

8 Knee External Rotation Web Sites

Radiologic Anatomy Browser http://radlinux1.usuf1.usuhs.mil/rad/iong • Agonists – This site has numerous radiological views of the musculoskeletal system. – Biceps Femoris University of Arkansas Medical School Gross Anatomy for Medical Students http://anatomy.uams.edu/anatomyhtml/gross.html – Dissections, anatomy tables, atlas images, links, etc. Loyola University Medical Center: Structure of the Human Body www.meddean.luc.edu/lumen/meded/grossanatomy/index.htm – An excellent site with many slides, dissections, tutorials, etc. for the study of human anatomy Wheeless’ Textbook of Orthopaedics www.wheelessonline.com/ – This site has an extensive index of links to the fractures, joints, muscles, nerves, trauma, medications, medical topics, lab tests, and links to orthopedic journals and other orthopedic and medical news. © 2007 McGraw-Hill Higher Education. All rights reserved. 10-49 © 2007 McGraw-Hill Higher Education. All rights reserved. 10-50

Web Sites Web Sites

Premiere Medical Search Engine Adam Healthcare Center www.medsite.com http://adam.about.com/surgery/100088.htm# – This site allows the reader to enter any medical condition and – Knee joint replacement it will search the net to find relevant articles. American Academy of Orthopaedic Surgeons Arthroscopy.com http://orthoinfo.aaos.org/category.cfm?topcategory=Knee www.arthroscopy.com/sports.htm – Patient education library on the knee – Patient information on various musculoskeletal problems of Edheads Activities the lower extremity www.edheads.org/activities/knee/ Virtual Hospital – Allows you to perform virtual knee surgery www.vh.org Gross Anatomy: The Functional Anatomy of the Knee Joint – Numerous slides, patient information, etc. www.upstate.edu/cdb/grossanat/limbs8.shtml Human Anatomy Online – Functional Anatomy of the Knee www.innerbody.com/image/musc08.html Knee Ligament Anatomy and Injury – Interactive musculoskeletal anatomy www.orthoassociates.com/knee_lig.htm The Hip and Knee Institute – Anatomy and injuries of the Knee and its ligaments www.hipsandknees.com/knee/index.html – Arthritis of the Knee Joint

Web Sites Web Sites

Duke Orthopaedics The Physician and Sportsmedicine www.wheelessonline.com/ortho/anatomy_and_kinematics_of_th www.physsportsmed.com/issues/1997/05may/bach.htm e_knee_joint – Acute Knee Injuries: When to Refer – Anatomy and Kinematics of the knee joint The Physician and Sportsmedicine Knee Injury: Meniscus www.physsportsmed.com/issues/1999/10_01_99/laprade.htm www.patient.co.uk/showdoc/27000672/ – Acute Knee Injuries: On-the-Field and Sideline Evaluation – Understanding the knee joint and purpose of meniscus Smart Play: The Knee www.smartplay.net/ouch/bodybits/b_bitsknee.html – Anatomy, functions, injuries, etc. of the knee Patellofemoral Instability www.massgeneral.org/ortho/PatellofemoralInstability.htm – Patella Femoral Alignment Chiroweb.com www.chiroweb.com/archives/21/24/03.html – Abnormal Q Angle and Orthotic Support