The Knee - Professor Scibek PDF

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Professor Scibek...

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The Knee EX-240 Tibiofemoral Joint - Complex joint that endures a great amount of trauma due to extreme amounts of stress that are regularly applied - Hinge joint with a rotational component - Stability is due primarily to ligaments, joint capsule, and muscles surrounding the joint - Designed for stability with weight bearing and mobility in locomotion - Consists of the femur and tibia - Femur  Medial and lateral condyles at the end  Convex structures covered with hyaline cartilage  Articulate with tibia - Tibia  Medial and lateral tibial plateaus  Correspond with femoral condyles  Medial concave both frontal and sagittal plane  Lateral concave in frontal, convex in sagittal  Medial 50% larger than lateral  Tibial Tuberosity  Attachment of Patellar tendon Other Bones of the Knee - Patella  Sesamoid bone  Improves mechanical advantage of knee  Protects anterior knee - Fibula  Soft tissues of lateral aspect of the leg attach to the fibular head  Can affect stability Knee Ligaments - Very little bony restraint - Frequently injured - Knee ligaments control*  Excessive knee extension  Varus and valgus stresses  Anterior and posterior tibial displacement  Medial and lateral rotation  Rotary stability *Function of ligaments can change depending on knee position Collateral Ligaments - Medial Collateral Ligament  Medial aspect of medial femoral condyle, sloping anteriorly to medial aspect of proximal tibia

 Resists valgus stress  Back up for pure anterior displacement when the ACL is absent - Lateral Collateral Ligament  Cordlike  Lateral femoral epicondyle to posterior head of fibula  Resists varus stress  Limits lateral rotation of tibia  Substantial contribution at 35 degrees of flexion Cruciate Ligaments - ACL and PCL - Located in tibiofemoral joint - Named according to tibial attachment - Anterior Cruciate Ligament  Anteromedial intercondylar eminence of tibia, travels posterior, passes lateral to PCL and inserts on medial wall of lateral femoral condyle  Serves as static stabilizer against:  Anterior translation of tibia on femur  Internal rotation of tibia on femur  External rotation of tibia on femur  Hyperextension of tibiofemoral joint  Anteromedial Bundle and Posterolateral Bundle  When the knee is in full extension, the attachment of the anteromedial bundle is anterior to that of the posteromedial bundle  When the knee is in flexion, the relative position is reversed  Various parts of ACL under tension in different positions - Posterior Cruciate Ligament  Arises from posterior tibia moving anteriorly and superiorly, passing medially to ACL and attaching on the lateral portion of the medial femoral condyle  Considered primary stabilizer of knee  Stronger and wider than ACL  Restricts posterior displacement of tibia on the femur and resists external rotation  Anterolateral Component  In range of 40-120 degrees of flexion it is primary restraint  Posteromedial Component  Primary restraint beyond 120 degrees  Meniscofemoral Component  When the knee is near extension support against posterior knee forces comes from popliteus, posterior capsule, and other structures A New Ligament!!! - Anterolateral Ligament (ALL)  First identified in 1879  Oblique course from the lateral epicondyle to the anterolateral tibia  Thought of as an extension of other tissues

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May control tibial internal rotation

Menisci - Deepen the articular surface of the tibial plateaus - Shock absorption - Increase stability of tibiofemoral joint - Improve lubrication of articular surface - From superior view they are concave, from front view they appear as wedge shaped - Very narrow vascular rim around outside, otherwise they are avascular  Tears in vascular area have an increased chance of healing - Medial Meniscus  C-shaped  Wider posteriorly than anteriorly - Lateral Meniscus  4/5 of a circle  Smaller and more mobile than medial meniscus Knee Flexors - There are 7 knee flexors  Semimembranosus, semitendinosus, biceps femoris, Sartorius, gracilis, popliteus, gastrocnemius - All are 2 joint except for the popliteus and short head of biceps femoris - BF can laterally rotate tibia - Create valgus and varus movements Knee Extensors - Quadriceps - Insert into quad tendon which becomes the patellar tendon - Vastus intermedius is the purest knee extensor - Influenced by the patella The Patellofemoral Articulation Anatomy of the PFA - Consists of patella and femur - Patella  Lies within the patellar tendon  Allows for increased efficiency  Protection of anterior portion of joint  Absorption and transmission of joint reaction forces  Covered with 5mm of hyaline cartilage  Tracks within the trochlear groove  Makes initial contact at 10-20 flexion  Seated within groove at 20-30  Greatest surface contact between 60-90  Compressive forces on patella moving through trochlea ranging from .5 x BW to 3.3 x BW  Patella’s position maintained by lateral retinaculum, medial retinaculum, and medial/lateral patellofemoral ligaments

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Proper firing order helps patella track correctly  VMO and VL fire at the same time  If this is off it leads to patellofemoral pain syndrome Proper foot position and flexibility of hamstring and lower leg musculature also necessary for proper function

Bursae - Suprapatellar  Deep at distal end of quadriceps  Allows free movement over distal femur - Prepatellar  Over anterior patella  Allows patella to move beneath skin - Subcutaneous infrapatellar bursa  Over tibial tuberosity  Protects distal patellar tendon from friction and blows - Deep infrapatellar bursa  Also protects distal patellar tendon from friction and blows - Infrapatellar fat pad  Separates patellar tendon and deep infrapatellar bursa from joint capsule of knee Patellar Position - Patella alta - Patella baja - Squinting patella - “frog eyed” patella Q-Angle - Lines which bisect the patella relative to the ASIS and tibial tubercle - Normal angle is 10 for males and 15 for females - Elevated angles often lead to pathological conditions associated with improperpatella tracking Summary - Capsular ligaments are taut during full extension and relaxed with flexion  Allows rotation to occur  Deeper capsular ligaments remain taut to keep rotation in check - PCL prevents excessive internal rotation, limits anterior translation and posterior translation when tibia is fixed and non-weight bearing, respectively - ACL stops excessive internal rotation, stabilizes the knee in full extension and prevents hyperextension - ROM includes 140 degrees of motion  Limited by shortened position of hamstrings, bulk of hamstrings and extensibilty of quads - Patella aids knee during extension providing a mechanical advantage  Distributes compressive stress on the femur by increasing contact between patellar tendon and femur  Protects patellar tendon against friction

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When moving from extension to flexion the patella glides laterally and further into trochlear groove Medial Collateral Ligament Sprain - MOI  Result of severe blow from lateral side (valgus force) - Signs and Symptoms  Grade 1  Little fiber tearing or stretching  Stable valgus test  Little or no joint effusion  Some joint stiffness and point tenderness on lateral aspect  Relatively normal ROM  Grade II  Complete tear of deep capsular ligament and partial tear of superficial layer of MCL  No gross instability; laxity at 5-15 of flexion  Slight swelling  Moderate to severe joint tightness with decreased ROM  Pain along medial aspect of knee  Grade III  Complete tear of supporting ligaments  Complete loss of medial stability  Minimum to moderate swelling  Immediate pain followed by ache  Loss of motion due to effusion and hamstring guarding  Positive valgus stress test Lateral Collateral Ligament Sprain - MOI  Result of a varus force, generally with the tibia internally rotated  If severe enough damage can also occur to the cruciate ligaments, ITB, and meniscus, producing bony fragments as well - Signs and Symptoms  Pain and tenderness over LCL  Swelling and effusion around the LCL  Joint laxity with varus testing  May cause irritation of the peroneal nerve Anterior Cruciate Ligament Sprain - MOI  Tibia externally rotated and valgus force at the knee (occasionally the result of hyperextension form direct blow)  May be linked to inability to decelerate valgus and rotational stresses- landing strategies  Male versus female  May involve damage to other structures including meniscus, capsule, and MCL

Posterior Cruciate Ligament Sprain - MOI  Most at risk during 90 degrees of flexion  Fall on bent knee is most common mechanism  Can also be damaged as a result of a rotational force - Signs and Symptoms  Feel a pop in the back of the knee  Tenderness and relatively little swelling in the popliteal fossa  Laxity with posterior sag test Meniscal Tear - MOI  Medial meniscus is more commonly injured due to ligamentous attachments and decreased mobility  Also more prone to disruption through torsional and valgus forces  Most common MOI is rotary force with knee flexed or extended  Tears may be longitudinal, oblique, or transverse - Signs and Symptoms  Effusion developing over 48-72 hour period  Joint line pain and loss of motion  Intermittent locking and giving way  Pain with squatting  Portions may become detached causing locking or catching within the joint  If chronic, recurrent swelling or muscle atrophy may occur Osteochondral Knee Fractures - MOI  Same MOI as collateral/cruciate ligaments or meniscal injuries  Twisting, sudden cutting, or direct blow  Fractures of cartilage and underlying bone varying in size and depth - Signs and Symptoms  Hear a snap and feeling of giving way  Immediate swelling and considerable pain  Diffuse pain along joint line Peroneal Nerve Contusion - MOI  Compression of peroneal nerve due to a direc blow - Signs and Symptoms  Local pain and possible shooting nerve pain  Numbness and paresthesia in cutaneous distribution of nerve  Added pressure may exacerbate condition  Generally resolves quickly  If it does not, could result in drop foot ITB Syndrome (Runner’s or Cyclist’s Knee) - MOI

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General expression for repetitive/overuse conditions attributed to mal alignment and structural asymmetries - Signs and Symptoms  ITB Friction Syndrome  Irritation at band’s insertion  Positive Ober’s test  Burning over lateral femoral condyle Pes Anserine Tendinitis or Bursitis - Result of excessive genu valgum and weak vastus medialis - Often occurs due to running with one leg higher than the other Knee Joint Rehabilitation - General body conditioning  Must be maintained with non-weight bearing activities - Weight bearing  Initial crutch use  Gradual progression to weight bearing while wearing brace - Knee joint mobilization  Used to reduce arthofibrosis  Patellar mobilization is key following surgery  CPM units - Flexibility - Muscular Strength - Neuromuscular Control - Bracing - Functional Progression - Return to activity...