Chapter 15: Knee Conditions Anatomy Copyright © 2017 Wolters Kluwer • All Rights Reserved Tibiofemoral Joint • Condyles of femur with plateaus of tibia • Hinge joint—flexion/extension • Tibia does rotate laterally on femur during last few degrees of extension – “Screw-home mechanism” • Produces a locking of the knee in final degrees during extension • Close-packed position of full extension Copyright © 2017 Wolters Kluwer • All Rights Reserved Meniscus • Fibrocartilaginous disks attached to tibial plateaus – Medial and lateral • Functions – Stabilize joint by deepening the articulation – Shock absorption – Provide lubrication and nourishment – Improve weight distribution Copyright © 2017 Wolters Kluwer • All Rights Reserved Joint Capsule and Bursae • Articular capsule—encompasses both tibiofemoral and patellofemoral joints – Suprapatellar bursa – Subpopliteal bursa – Semimembranosus bursa • Bursa outside capsule – Prepatellar bursa – Superficial infrapatellar bursa – Deep infrapatellar bursa Copyright © 2017 Wolters Kluwer • All Rights Reserved Ligaments • ACL – Prevents • Anterior translation of tibia on femur • Rotation of tibia on femur • Hyperextension – Discrete bands • Knee full extension—posterolateral bundle is taut • Knee full flexion—anteromedial bundle is taut Copyright © 2017 Wolters Kluwer • All Rights Reserved Ligaments (cont.) • MCL – Resist medially directed (valgus) forces – Complete extension—taut midrange—posterior fibers most taut complete flexion—anterior fibers most taut • LCL – Resist laterally directed (varus) forces Copyright © 2017 Wolters Kluwer • All Rights Reserved Ligaments (cont.) • PCL – Resists posterior displacement of tibia on femur – Knee full extension—posterior fibers are taut; knee full flexion—anterior fibers are taut Copyright © 2017 Wolters Kluwer • All Rights Reserved Iliotibial Band • Extends from tensor fascia latae to Gerdy tubercle on lateral tibial plateau • Lateral knee stabilizer Copyright © 2017 Wolters Kluwer • All Rights Reserved Patellofemoral Joint • Patella – Superior, middle, and inferior articular surfaces – Functions • Protect femur • Increase effective power of quadriceps Copyright © 2017 Wolters Kluwer • All Rights Reserved Q-Angle • Q-angle – Angle between line of resultant force produced by quadriceps and line of patellar tendon – Males 12°; females 22° Copyright © 2017 Wolters Kluwer • All Rights Reserved Muscles • Produce movement • Stabilize the knee Copyright © 2017 Wolters Kluwer • All Rights Reserved Blood Supply • Femoral artery • Popliteal artery • Genicular arteries Copyright © 2017 Wolters Kluwer • All Rights Reserved Kinematics • Knee flexion – Hamstrings – Assisted by • Popliteus • Gastrocnemius • Gracilis • Sartorius Copyright © 2017 Wolters Kluwer • All Rights Reserved Kinematics (cont.) • Knee extension – Quadriceps femoris muscle group • Rectus femoris • Vastus lateralis • Vastus intermedius • Vastus medialis • Vastus medialis oblique (VMO) – Screwing-home motion • Rotation and passive abduction and adduction – Capability maximal at approximately 90° of knee flexion Copyright © 2017 Wolters Kluwer • All Rights Reserved Prevention of Knee Injuries • Physical conditioning – Strength – Flexibility • Rule changes • Footwear – Cleats versus flat sole – Position of cleats and size Copyright © 2017 Wolters Kluwer • All Rights Reserved Assessment • History • Observation/inspection • Palpation • Physical examination tests Copyright © 2017 Wolters Kluwer • All Rights Reserved Contusions • Knee – Mechanism: compression – Signs and symptoms • Localized tenderness • Pain • Swelling – Management: standard acute – Caution: excessive swelling could mask other injuries Copyright © 2017 Wolters Kluwer • All Rights Reserved Ligamentous Conditions (cont.) Copyright © 2017 Wolters Kluwer • All Rights Reserved Ligamentous Conditions (cont.) • Straight medial instability (valgus laxity) – Involves MCL; posterior medial capsule—possibly PCL – Lateral forces cause tension on medial aspect of knee – First degree • Mild pain medial joint line • Little or no joint effusion/mild swelling at site • Full ROM with minor discomfort • Valgus: 0°, stable; 30º, + Copyright © 2017 Wolters Kluwer • All Rights Reserved Ligamentous Conditions (cont.) • Straight lateral instability (varus laxity) – Involves LCL, lateral capsular ligaments, PCL – Medial forces produce tension on lateral aspect of knee • Not usually isolated—presence of IT band, biceps femoris, popliteus Copyright © 2017 Wolters Kluwer • All Rights Reserved Ligamentous Conditions (cont.) – Signs and symptoms • Similar to MCL • Swelling minimal—no attachment to capsule • + varus: 30º • Instability may not be obvious if other stabilizers are intact Copyright © 2017 Wolters Kluwer • All Rights Reserved Ligamentous Conditions (cont.) • Straight anterior instability (anterior instability) – Anterior displacement of tibia on femur – Involves ACL—rarely isolated – Mechanism: cutting or turning maneuver, landing, or sudden deceleration Copyright © 2017 Wolters Kluwer • All Rights Reserved Ligamentous Conditions (cont.) – Signs and symptoms • Pain Minimal and transient to severe and lasting Deep in knee difficult to pinpoint • “Pop” • Effusion within 3 hours; reports knee giving way— does not feel right Copyright © 2017 Wolters Kluwer • All Rights Reserved Ligamentous Conditions (cont.) • Straight posterior instability – Tibia displaced posteriorly – Involves PCL – Mechanism • Hyperextension force • Fall on flexed knee (initial contact at tibial tuberosity) Copyright © 2017 Wolters Kluwer • All Rights Reserved Ligamentous Conditions (cont.) – Signs and symptoms • Sense of stretching to posterior knee • “Pop” • Rapid joint effusion • ↓ knee flexion caused by effusion • + reverse Lachman test; posterior sag Copyright © 2017 Wolters Kluwer • All Rights Reserved Ligamentous Conditions (cont.) • Anteromedial instability – Anterior external rotation of medial tibia condyle on femur – Involves MCL and oblique popliteal ligament, potentially ACL and medial meniscus – Signs and symptoms • + valgus: 0° and 30° • + Slocum drawer test; + Lachman test • ↑ anterior translation of the medial tibial plateau (with special tests) Copyright © 2017 Wolters Kluwer • All Rights Reserved Ligamentous Conditions (cont.) • Management – Standard acute; NSAIDs – Physician referral—timing dependent on severity Copyright © 2017 Wolters Kluwer • All Rights Reserved Copyright © 2017 Wolters Kluwer • All Rights Reserved Knee Dislocation/Subluxation • Minimum of three ligaments must be torn for knee to dislocate – Most often—ACL, PCL, and one collateral ligament • Concern: damage to other structures; especially neurovascular • Signs and symptoms – Individual describes severe injury – “Pop” – Deformity (unless spontaneously reduced) • Management: standard acute – Spontaneous reduction—physician referral – Not reduced—activate EMS Copyright © 2017 Wolters Kluwer • All Rights Reserved Meniscal Conditions • Classified according to location • Involve compression, tension, shearing forces • Longitudinal – Twisting motion when foot fixed and knee flexed • Produces compression and torsion on posterior peripheral attachment – Bucket-handle tear • Longitudinal segment displaced medially toward center of tibia Copyright © 2017 Wolters Kluwer • All Rights Reserved Meniscal Conditions (cont.) • Horizontal tear – Due largely to degeneration – Shearing from rotational forces • Tears the inner surface of the meniscus – Parrot-beak tear • Two tears; commonly in middle segment of lateral meniscus Copyright © 2017 Wolters Kluwer • All Rights Reserved Meniscal Conditions (cont.) Copyright © 2017 Wolters Kluwer • All Rights Reserved Meniscal Conditions (cont.) • Signs and symptoms – Initial symptoms may be vague or limited • Limited sensory nerve supply—minimal pain • Minimal disability • Minimal swelling – Understand mechanism – Delayed swelling – Joint line pain – Classic: clicking/locking (not acutely) leads to knee buckling or giving way – + McMurray; Apley compression; “bounce home” test Copyright © 2017 Wolters Kluwer • All Rights Reserved Meniscal Conditions (cont.) • Management – Standard acute; treat symptoms – Physician referral Copyright © 2017 Wolters Kluwer • All Rights Reserved Patellar Conditions (cont.) • Chondromalacia – Degeneration in articular cartilage of patella – Caused by abnormal excursion and compressive forces – Signs and symptoms: • Localized tenderness • Anterior knee pain • + Clarke test; + Waldron test – Management • Standard acute • Activity modification Copyright © 2017 Wolters Kluwer • All Rights Reserved Patellar Conditions (cont.) • Patellar instability and dislocation – Displacement of patella caused by internal or external forces – Mechanism: deceleration combined with a cutting motion – Signs and symptoms subluxation • Transient partial displacement; acute or intermittent with spontaneous reduction • Feeling of patella slipping when cutting, twisting, or pivoting • + apprehension test Copyright © 2017 Wolters Kluwer • All Rights Reserved Patellar Conditions (cont.) – Signs and symptoms dislocation • “Pop” • Violent collapse of the knee • Localized tenderness—medial extensor retinaculum • Effusion – Management: standard acute; immediate physician referral Copyright © 2017 Wolters Kluwer • All Rights Reserved Patellar Conditions (cont.) Copyright © 2017 Wolters Kluwer • All Rights Reserved Patellar Conditions (cont.) • Patellar tendinitis – Caused by repetitive or eccentric knee extension activities – Signs and symptoms • Initial—pain after activity on inferior pole of patella or distal attachment of patellar tendon • Progression—pain at start of activity, subsides with warm-up, reappears after activity • Pain ascending and descending stairs • Pain with passive knee flexion beyond 120° and resisted knee extension – Management: standard acute; NSAIDs Copyright © 2017 Wolters Kluwer • All Rights Reserved Patellar Conditions (cont.) • Osgood-Schlatter disease – Inflammation or partial avulsion of tibial apophysis caused by traction forces – Signs and symptoms • Individual points to tibial tubercle as source of pain • Tubercle appears enlarged • Pain during activity and relieved with rest • Pain at extreme knee extension and forced flexion – Management: treat symptoms; self-limiting Copyright © 2017 Wolters Kluwer • All Rights Reserved Patellar Conditions (cont.) Copyright © 2017 Wolters Kluwer • All Rights Reserved Fractures and Associated Conditions (cont.) • Patellar fractures – Transverse – Stellate – Comminuted – Longitudinal • Pain, visible defect • Ice, elevation, immobilization, referral Copyright © 2017 Wolters Kluwer • All Rights Reserved Rehabilitation • Restoration of proprioception and balance – Closed chain exercises • Muscular strength, endurance, and power – Open chain exercises – PNF-resisted exercises • Cardiovascular fitness Copyright © 2017 Wolters Kluwer • All Rights Reserved Rehabilitation (cont.) • Range of motion Copyright © 2017 Wolters Kluwer • All Rights Reserved Rehabilitation (cont.) • Patellar self-mobilization Copyright © 2017 Wolters Kluwer • All Rights Reserved Rehabilitation (cont.) • Closed chain terminal extension Copyright © 2017 Wolters Kluwer • All Rights Reserved
