Meniscal Injury

Meniscal TearAnatomyMeniscus otherwise called semilunar cartilages, are two asymmetric fibrocartilagenous joint disks. The medial meniscus is a semicircle, while the lateral meniscus is four fifths of a ring. Both menisci are open toward the intercondylar area, thick peripherally and thin centrally, forming concavities into which the respective femoral condyles can sit. The wedge shaped menisci increase the radius of curvature of the tibial condyles and therefore joint congruence. By increasing the congruence or articular contact, the menisci also play an important role on distributing weight bearing forces and in reducing friction between the joint segments.The medial meniscus is more firmly attached than the lateral meniscus. Its lack of mobility may be one of several reasons why the medial meniscus is torn more frequently than the lateral meniscus.The menisci are well established in the 8-week old embryo. Initially well vascularized, the vascularity of the menisci gradually recedes centrally outward, reaching adult form at 10 or 11 years of age. The adult meniscus is vascularized only at the periphery by capillaries from the joint capsule and synovial membrane. The pattern of vascularity may account for the low incidence of meniscal injuries in young children whose menisci have ample blood supply and the ability of the menisci to regenerate only in the vascularized peripheral region.Etiology1. Traumatic Injury2. Degenerative causes prolonged hyperflexion of the knee particularly kneelingMechanism of InjuryThe medial meniscus acts as a pivot during axial rotation. Meniscal injuries usually occur as a result of sudden rotation of the fixed tibia when the knee is in flexion. The mechanism of injury or a meniscal tear is a combination of torsion and impact stress placed on the joint with secondary tearing of the cartilage substance. The medial meniscus is more commonly torn than the lateral meniscus. This is because the medial meniscus is less mobile due to its more rigid attachment, and thus when the knee is subjected to rotational forces; it will not move accordingly with the moving structures, and what results is a meniscus that is torn.Medial meniscus injury usually occurs when the foot is fixed on the ground and the femur is rotated internally, while lateral meniscal injury commonly occurs when the femur is rotated externally on a fixed tibia. An ACL injury often accompanies a medial meniscus tear.

ClassificationVertical tears Longitudinal tear Tear along the longitudinal axis of the meniscus Radial tear Tear transverse to the circumferential fibers of the meniscus Bucket handle tear Complete longitudinal tear that results in a peripheral and inner fragmentHorizontal tears Transverse tear Tear in the horizontal axis of the meniscus Cleavage tear Complete transverse tear that separates meniscus into superior and inferior fragmentsParrots beak tear Combined, incomplete radial and longitudinal tear, with a displaceable component that resembles a parrots beakRoot tear Tear in the ant or post meniscal roots where the meniscus attaches to the central tibial plateauDegenerative tear Occur as a result of traumatic or degenerative arthritis

Clinical Manifestations: Locking of knee Unable to fully extend Springy end feel Pain along joint line Unable to bear weight Unexpected giving way of knee during amb Joint swelling Slight LOM of flexion/extension Quadriceps atrophyComplications Non-operative treatment Knee instability Chronic pain OA Tear extension Surgical Intraoperative damage to neurovascular bundle Medial meniscus repair saphenous nerve Lateral meniscus peroneal Flexion contracture Extensor lag Risk of failure of repair Joint loading Knee flexion beyond 45 Greatest during first few mos. post-opDifferential DiagnosisConditionS/SxMechanism of InjurySpecial Test

Cruciate Ligament InjuriesACLPCL Pain LOM Area of affectation

Hyperextension or from a valgus force to the knee Posterior force to a bent knee

(+) Anterior drawer test(+) Posterior drawer test(+) Lachman test

Runners Knee Pain LOM

Abnormal lateral tracking of patella

(+) Clarkes test

Meniscal Injury Locking Pain LOM Swelling Atrophy

Slightly flexed knee with foot planted on ground with sudden twisting of femur

(+) Mcmurrays Test(+) Apleys Test (+) Bounce Home Test

Diagnosis Hx Occur from excessive loads on normal meniscus Rot force as a flexed knee comes into extension Also from normal forces acting on a degenerative meniscus PE Special Tests Mcmurray test Px supine, knee acutely & forcibly flex PT checks the med men by palpating posteromed margin of jt w/ 1 hand while grasping foot w/ other hand ER knee as far as possib., then slowly extend (+)if A painful click/pop felt/ heard As femur passes over tear in the men Lat men is checked by Palpating the posterolat margin of the jt IR as far as possib. & slowly extend the knee while listen/feel for click (-) McMurray test does not r/o tear Bounce Home Test Pt Supine Knee fully flexed then passively extend (+) incomplete extension, rubbery endfeel Apley grinding test Prone knee flexed 90 Ant thigh fixed against the table Foot & leg are then pulled upward to distract jt & rot to place rot strain on ligs When ligs torn Pain on this part of the test w/ knee in same posn Press downward & rot foot & leg as jt is slowly flex & extend When men torn (+) popping & pain localized to jt line noted

MRI diagnostic imaging of choiceMRI acc. in detection of men tear is 95% Grade 0 - N men Grade I - Stellate intrameniscal tear signal that does not extend to a free articular surface Grade II - Linear intrameniscal tear that does not extend to the articular surface Grade III - Sig change in the meniscus that does not extend to the articular surface represents a torn meniscus Arthroscopy yields information of greatest diagnostic value X-ray to rule out fracture, loose bodies, arthritis

Medical Surgical ManagementPartial Menisectomy Indications: Symptomatic, displaced tear by older and inactive individuals Tear extending into central less vascular third Tear localized to inner avascular thirdMeniscal Repair Indications: Lesions in the vascular one third Tear extending into the central avascular third of a young (less than 40 50) or physically active older (greater than 50)Contraindications Tear localized to the inner avascular third Considerable tissue fragmentation Tear that cant be reopposed

Allograft transplantationis a type of surgery in which a meniscus is placed into your knees. The new meniscus is taken from a cadaver.

Aspiration to remove excess fluid in the acute stage