The Knee Joint is the largest & most complicated joint inthe body .- It consists of 3 Joints within a single synovial cavity : Medial Condylar Joint : Between the medial condyle“of the femur” & the medial condyle “of the tibia” . Latral Condylar Joint : Between the lateral condyle“of the femur” & the lateral condyle “of the tibia” . Patellofemoral Joint : Between the patella & thepatellar surface of the femur .- The fibula is NOT directly involved in the joint
Capsule : Surrounds the sides & posterioraspect of the joint. On the frontal side, the capsule is absent . On each side of the patella , thecapsule is strengthened by the tendonsof Vastus Lateralis & Vastus Medialis .
Ligaments :1 .Extracapsular Ligaments : Ligamentum Patelleaa continuation of the Quariceps Femorismuscle - Lateral Collateral Lig. - Medial Collateral Lig. - Oblique Popliteal LigDerived from the Semimembranosusmuscle
2. Intracapsular Ligaments :Cruciate Ligaments :2 strong ligaments that cross each other within thejoint cavity . Anterior Cruciate Ligament (ACL)Attached to the anterior intercondylar areaof the tibia , passes upward , backward &laterally to get attached to the lateral femoralcondyle . Prevents posterior displacement of thefemur (( With the knee joint flexed , the ACLprevents the tibia from being pulled anteriorly Posterior Cruciate Ligament (PCL)Attached to the posterior intercondylar area of the tibia , passesupward , forward , & medially to get attached to the medialfemoral condyle .Prevents anterior displacement of the femur With the knee jointflexed , the PCL prevents the tibia from being pulled posteriorly .
Thick, circular-triangular bone which articulates with the femur and coversand protects the anterior articular surface of the knee joint. It is thelargest sesamoid bone.Anterior surfaceIt can be divided into three parts: The upper third is coarse, flattened,and rough; it serves for the attachmentof the tendon of the quadriceps and often has exostoses. The middle third has numerous vascular canaliculi. The lower third includes the distal apex which serves asthe origin of the patellar ligament.Posterior surfaceThe upper three-quarters articulates with the femur andis subdivided into a medial and a lateral facet by avertical ledge which varies in shape.
It is attached to the tendon of the quadriceps femorismuscle, which contracts to extend/straighten the knee.The vastus intermedialis muscle is attached to the base ofpatella. Thevastus latus lateralis and vastus medialis areattached to lateral and medial borders of patella respectively. The knee is normally in slight valgus so there is a naturaltendency for the patella to pulled to the lateral side when thequadriceps muscle is contracted The patella is stabilized by the insertion of vastus medialis andthe prominence of the anterior femoral condyles, whichprevent lateral dislocation during flexion. When injuries occur, all structures are simultaneouslyaffected.These ligaments hold the patella in placeduring static and dynamic phases.
Flexion : these muscles produce flexion :Biceps femoris, Semitendinosus, Semimembranosus,Gracilis, Sartorius, Popliteus .Flexion is limited by the contact of the back of the leg withthe thigh .- Extension by the Quadriceps femoris . Extension is limited by the tension of all the ligaments ofthe joint .- Medial Rotation : by the Sartorius , Gracilis , Semtendinosus. Lateral Rotation : by the Biceps femoris .
Clinic c/o: middle age patient complainof pain starts insidiously andincreaseslowly over time ( months andyears)aggravated by exertion andrelieved byrest, with time relief is less and lesscomplete. Stiffness :mainly after rest Symptoms follow an intermittentcourse with periods of remissionlasts for months In advance stage : deformity,swelling, muscle wasting and lossof mobility . No systemic manifestations incontrast to inf. diseases.
Osteoarthritis (OA) : a chronic inflammatoryjoint disorder in which theres progressivesoftening & destruction of the articularcartilage, accompanied by new growth ofcartilage and bone at the joint margins(osteophytes) and capsular fibrosis...leading to bone exposure & severe pain . OA is the most common joint dis. The knee is the most common
It can be primary or secondary :Usually it’s Primary ( Idiopathic ) &affecting both knee joints (Bilateral) Secondary causes might be :Trauma , localized or metabolicdiseases , mechanical factors,Bone Dysplasia , etc
Trauma Congenital or developmental Metabolic Endocrine Calcium deposition diseases Other bone and joint diseases Neuropathic (Charcot joints) Endemic Miscellaneous
1. OA results from adisparity between the stressapplied to the articularcartilage & the ability of thecartilage to withstand thatstress , due to :› Weakening of the articular cartilage ( genetic defect in collagen type llor inflammatory disorder “RA” ) .› Increased mechanical stress in some parts of the articular surface.2. The abraded bone under a cartilage ulcer may take on theappearance of ivory (eburnation = the bony sclerosis whichoccurs at the areas of cartilage loss.). Growth of cartilage andbone at the joint margins leads to osteophytes (spurs), which alterthe contour of the joint and may restrict movement
Appositional bonegrowth occurs in thesubchondral region- seen radiographically - Synovitis & thickening ofthe joint capsule mayoccur & further restrictmovement Periarticular musclewasting is common &may play a major role insymptoms .
Narrowing of jointspace. Subarticular cystformation and sclerosis. Osteophyte formation. Evidences of 2ndrycauses e.g. oldfracture.The first two are restricted initially to themajor load-bearing part of the joint butlater the entire joint is affected.