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The Thigh, Leg, and Knee The Knee Bones of the Knee include the femur, tibia, and patella. The Fibula, the lateral bone of the lower leg is technically not a part of the knee joint. Femur: - Thigh bone Longest, strongest, heaviest bone in the body The head of the femur is attached to the shaft by a region known as the neck – susceptible to fractures Has rounded condyles and epicondyles distally Tibia: - Lateral and medial condyles proximally Tibial tuberosity is the site of attachment of the patellar tendon (Quadriceps) Medial malleolus distally Patella: - Kneecap Largest sesamoid bone - a bone that is embedded within a tendon. Sesamoid bones are found in areas where tendons pass over joints - lateral lower leg bone Head of the fibula is proximal Lateral malleolus is distal Fibula: The Femur, Tibia, and Patella form 2 separate joints at the knee: 1. Tibiofemoral joint Formed by the femur superiorly and the tibia inferiorly. It is a hinge joint that primarily permits flexion and extension (but there is gliding and rolling of the tibia on the femur) 2. Patellofemoral joint Formed by the patella and the femur – gliding joint Muscles of the Thigh Can be divided into 3 basic regions: Anterior thigh - The quadriceps - Vastus medialis, vastus lateralis, vastus intermedius, rectus femoris - Extend the leg at the knee joint - Rectus femoris also cross the hip joint and acts as a hip flexor Posterior thigh Medial thigh - The hamstrings Biceps femoris, semimembranosus, semitendinosus Flex the leg at the knee joint Adductors Adductor longus, adductor magnus, adductor brevis, gracilis Adduct the thigh and assist with flexion The Sartorius is also a thigh muscle that originates on the hip, runs diagonally down the thigh, and attaches to the medial tibial condyle. Muscle and Actions MUSCLE GROUP Quadriceps ACTION(S) Rectus Femoris Knee Extension, Hip flexion Vastus Medialis Vastus Lateralis Knee Extension Knee Extension Vastus Intermedius Knee Extension MUSCLE GROUP Hamstrings ACTION(S) Semitendinosus Knee Flexion Semimembranosus Knee Flexion Biceps Femoris Knee FLexion MUSCLE GROUP Adductors ACTION(S) Adductor Longus Thigh Adduction Adductor Magnus Thigh Adduction Adductor Brevis Thigh Adduction Gracilis Thigh Adduction Sartorius Tensor Fascia Latea Knee flexion Hip abduction, internal rotation, flexion Hip flexion Knee extension The Knee Ligaments The knee has many ligaments supporting the joint, however, there are 4 major ligaments that serve to stabilize the joint. 1. The Cruciate Ligaments Located inside the knee joint a. Anterior Cruciate Ligament (ACL) prevents forward displacement (movement) of the tibia and prevents hyperextension b. Posterior Cruciate Ligament prevents posterior displacement of the tibia it is the largest and strongest ligament in the knee 2. The Collateral Ligaments a. Medial Collateral Ligament (MCL) Primary structure that supports the medial aspect of the knee Connects the femur to the tibia Provides stability against a valgus stress b. Lateral Collateral ligament (LCL) Provides lateral stability to the knee Connects the femur to the head of the fibula Provides stability against a varus stress The Knee Meniscus A pair of half-mooned, wedged shaped cartilages (the lateral and medial meniscus) found between the femur and the tibia. Blood supply to the meniscus is limited to the outer 25% of the structure – it is basically AVASCULAR. Functions: 1. Shock absorbers 2. Increase the surface area for contact between the femur and the tibia 3. Increases stability of the knee joint Conditions and Injuries to the Knee Knock Knees - Knees touch, but the ankles do not touch - By puberty, the legs begin to straighten out - aka Genu Valgum - Can Result From a Problem or Disease: a. Tibial injury b. Osteomyelitis (bone infection) c. Overweight or obesity d. Rickets – disease due to lack of vitamin D - Treatment Usually not treated Surgery if it is severe and past late childhood If caused by a disease such as rickets or osteomyelitis, treat the disease Bowleg - Knees stay wide apart with ankles and feet together Normal in children under 18 months Due to folded position in the uterus When baby becomes weight bearing, they straighten out - May be caused by illness: a. Blounts disease – disease in children in which the tibia fails to develop normally b. Bone dysplasia – abnormal bone growth c. Fractures that heal incorrectly d. Lead or fluoride poisoning e. Rickets - No treatment unless severe Genu Recurvatum - Excess extension at the tibiofemoral joint Knee hyperextension Causes a. Knee laxity b. Quadriceps weakness c. Poor tibia or femur alignment d. Hip extensor weakness Patellofemoral Disorders Problems with patella – most common cause of knee pain Anatomy: - Patella is a sesamoid bone formed in Quad tendon - Patellofemoral joint – patella and femur - Compression forces – <body weight during walking 2.5 x body weight during stairs The Q Angle - The Q angle of the knee is a measurement of the angle between the quadriceps muscles and the patella tendon and provides useful information about the alignment of the knee joint. Patellar Tendinitis Jumper’s Knee” Inflammation and degeneration of the tendon that connects the kneecap (Patella) to the shin bone (Tibia). Chondromalacia Damage to the cartilage under the kneecap Causes: abnormal patellar tracking Most Common Symptom: Knee pain when walking up and down stairs Prevention: strengthen quads Minimize squats, downhill running, biking with low seat Patellar Dislocation Involves the patella sliding out of its position on the knee. Caused by direct blow or abnormal twisting of the knee Usually lateral Osgood Schlatter 1. Painful swelling over tibial tuberosity (patellar tendon insertion) 2. Usually occurs between 9-13 years of age 3. Pain increases with activity Iliotibial Band Friction Syndrome Occurs where IT Band rubs over femur at the knee joint Common in running (esp. downhill) or any activity with repetitive flexion Hills or stairs increase pain Lots of IT Band stretching Popliteal Cyst “Baker’s Cyst” Fluid accumulation in posterior knee (popliteal space) Patient usually complains of a mass behind the knee Prepatellar Bursitis “Housemaid’s Knee” Tender swelling over the kneecap (prepatellar bursa) Pes Anserine Bursitis Inflammation of a bursa in your knee. The pes anserine bursa is located on the inner side of the knee just below the knee joint. Tendons of three muscles attach to the shin bone (tibia) over this bursa SGT: Sartorius, Semitendinosis, Gracilis ACL Sprain 1. MOI: twisting of knee forced hyperextension lateral blow to knee *foot must be firmly anchored to playing surface 2. 50% of people describe a “pop” in knee 3. Knee fills with blood quickly Hemarthrosis 4. Usually immediate loss of motion 5. Knee feels unstable Anterior Drawer Test: examiner attempts to slide the tibia forward which may indicate a torn ACL ligament Surgery Arthroscopic Graft options Patellar Tendon Semitendinosus Gracilis Cadaver Synthetic PCL Sprain 1. MOI: excessive hyperextension hyperflexion tibia forced posteriorly (blow to front of knee) “dashboard knee” Possibly 90% of all PCL injuries due to motor vehicle accidents? 2. 3. 4. 5. 6. Mild hemarthrosis Posterior knee pain Walk with knee slightly flexed, avoid full extension Posterior sag of tibia Surgery? MCL Sprain MOI: Blow to the outside of the knee = Valgus Force Possible overuse – breaststroke in swimmers Commonly associated with meniscal injuries – attached to medial meniscus No surgery Valgus Stress Test: tests for injury to the MCL ligament Varus Stress Test: tests for injury to the LCL ligament Meniscal Injuries 1. MOI: Rotation of the knee as the pivoting knee extends during rapid cutting or 2. Signs and Symptoms: - pain - joint line tenderness - catching or locking - knee buckling or giving way - swelling - incomplete flexion - clicking on stair climbing 3. Surgery? Meniscectomy: removal of the meniscus - Total meniscectomy = osteoarthritis Depends on location of tear, type of tear, and blood supply