MENISCAL INJURIES

ANATOMY•Medial and lateral menisci are two semilunar plates of fibrocartilage that are placed on the condylar surface of the tibia•They are tibial extension that creates conformity b/w the relatively flat tibial surface and round femoral condyles•Made up of type 1 collagen with some type 2 and some elastin fibers•Arranged in circumferential hoops and radial

Medial meniscus•Medial menisci is three fifth of a ring; semicircular•Asymmetrically larger posteriorly than anteriorly and fixed to tibia and femur thru the coronary ligaments•Bld supply : medial superior and inferior geniculate arteries•Nerve innervation accompanies peripheral vascularity•Less mobile•Antr horn attached to tibial intercondylar eminence (infront of ACL)•Postr horn attached to intercondylar area (in front of PCL)

Lateral meniscus•More circular,makes four fifth of a ring with symmetrical antr and postr horns•It has got a hypovascular zone in the area of popliteus tendon hiatus.•In this area it has no peripheral/capsular attachments•Hence greater mobility to lateral meniscus•Antr horn attached to intercondylar eminence of tibia lateral to ACL•Posterior horn attached to intercondylar eminence

L

M

Vascular supply good in the most peripheral 20% of the fibersSupplied by the geniculate

arteriesInner 1/3 of the ring is

avascularRelatively thinNourished through synovial

fluidMiddle 1/3 of the ring is

combination

Functions • joint stabilization•Tibio-femoral stress reduction•Joint nutrition•Wt transmission –abt 40-70 % across the knee joint•As a shock absorber•Increase the tibiofemoral contact area by 40 %•Helps knee in locking mechanism•Prevents impingement of synovial membrane,capsule etc•Assists and control gliding and rolling motion of knee

Medial meniscus is more commonly injured than lateral meniscus and is usually associated with other ligament injuriesSeen in abt 71 % of cases,and 5% its bilateralLateral meiscus is less injured because:oSmaller in diameteroThicker in peripheryoWideoMore mobileoAttached to both cruciate ligoStabilised postiorly to the femoral condyle by popliteus

Mechanism of injury•Rotational force when a flexed knee extends•Twisting strain when knee is flexed ;young active athlets are more prone•In middle aged: fibrosis decreases the mobility and hence tear occurs with less force

An acute twisting injury from impact during a sportUsually the foot stays fixed on the ground and

the rest of body rotates.Rotational force while jt is partially flexed

Getting up from a squatting or crouching Position.

Associated injuriesIn acute knee injuries with ACL intact, medial

meniscal injury is 5 times more likely than lateral

In acute knee injuries with ACL ruptured, lateral meniscus more likely to be involved

If ACL is previously disrupted, lateral meniscal injury is more likely than medial

In repetitive deep squatting, medial meniscus most likely to be injured

symptomsNot all meniscal tears are symptomatic

SwellingPain along the joint line (tenderness)Pain when squatting, kneeling or pivotingLocking of the kneeGiving way snaps, clicks, catches in knee.Atrophy of quadricepsInstability of joint

Signs: Locking positive : Restriction of the last few terminal

degrees of extension of the knee Mc murray’s test positive Hip and knee flexed at 90 degree,with

examiner’s hand over the knee internal and external rotation of knee is done for lateral and medial menisci resp.positive test requires both pain and click to be felt by the examiner

Joint line tenderness positive medial joint line tenderness is elicited

when knee flexed to 60 degrees and leg externally rotated.positive in 74 % cases of medial meniscal injuries

Quadriceps atrophy positive Steinmanns sign Meniscal pathology may be suspected

if medial pain is elicited on lateral rotation And lateral pain on medial tibial rotation

Apley’s compression test positive Pt in prone position,fixing the thigh against

the table,the examiner presses the foot and leg downward while rotating the tibia,pain implies meniscal lesion.pain on lateral rotation indicates a medial meniscal tear

Apley’s Distraction TestHere the examiner pulls the foot and leg

upward to distract the joint while again rotating the tibia.pain noted during axial distraction of joint implies a ligamentous lesion

Classification Based on appearance on

arthroscopy :

1. Radial/parrot beak tears2. Flap tears3. Degenerative tears4. Bucket handle tears(vertical)5. Horizontal tears

L R H

B P S

Investigations:Initial plain xray : To R/O ass. #,ligamentous avulsion, or arthritic change,soft tissue swelling

MRI cuts usually proceed from medial to lateral lateral meniscus is symmetrical in sagital view and has appearance of a bowtie

Arthroscopy

On MRI meniscal tears are graded 1 to 4o Grade 1 tear has an increased signal in the

meniscal substanceo Grade 2 change involves a more pronounced

and frequently linear signal that does not break the surface of the meniscus.

grade 1 and 2 appears normal on arthroscopic evaluation

o Grade 3 change is a signal that traverses through the meniscal surface and will be noted as tear on arthroscopy in 80% of cases

o There is extension of tear through both the tibial and femoral surfaces of the meniscus

locked bucket handle tear usually involves medial meniscus and is seen as ‘double PCL sign’ on sagittal images

Treatment Depends on age, presence of arthritis, damage or deformity of meniscus, and association of cruciate ligament tear etcConservative in patient’s soon after injury with no locking and with infrquent attacks of pain and in tears less than 10mm,partial thickness tearsSurgery if joint cannot be unlocked and if symptoms are recurrent

Conservative 1. Abstinence from weight bearing2. Rest,ice packs,compressive bandage3. Buck’s skin traction4. Joint aspiration5. Quadriceps exercises6. If symptoms persists,a cylindrical

cast may be considered

Total meniscectomyPartial meniscectomyMeniscal repair

Inside outOutside inAll inside

Partial MeniscectomyDone when tear involves interior 70%May be done when athlete wants to resume

activity ASAPDone with mobile fragments10-35 minute arthroscopic procedure under

regional or general anestheticMobile areas removedEdges contoured to “prevent further tears”

Immediate partial weight bearing allowedCrutches for 1-2 days

Total meniscectomyIrreparably torn meniscusNot a treatment of choice in young athletsSteps: anteromedial incision medial to patella upto

upper tibia.Incise capsule and fascia.Lift the synovium and make a small opening.Extent the opening proximally and distally

and examine the structures of joint

Palpate the meniscus on both surface entirely with meniscal hook.

Mobilise anterior 1/3 with scalpel.Middle 1/3 by retracting tibial collateral

ligament.Then mobilise posterior 1/3 of menisci.Check the medial and antr stability of knee

joint.

Consequences of Meniscectomy increased osteophyte formation and femoral

cartilage deterioration in meniscectomized knee

In medial meniscectomy, load bearing surfaces are halved, doubling stress on tibial plateau

Complications:•Infection•Nerve palsy (saphenous,tibial,peroneal)•Vascular injury•Post op effusion : sign of hyaline cartilage injury. Trt:ice,anti inflammatory agents,chondroprotective agents

•Reflex sympathetic dystrophy –decrease range of motion with pain Trt: aggressive pain control,rehabilitation, sympathetic blocks ,continued limitation of motion,arthroscopy,manipulation and post operatively continuous epidural block can effectively manage RSD

Post op hemarthrosisc/c synovitisInjury to popliteal vesselsPainful neuromas of infra patellar branch of

saphenous nerveThrombophlebitis

Meniscus RepairArthroscopically aid repair Used in longitudinal tears,vascularised zone Through posteromedial arthrotomy multiple

interrupted sutures placed vertically through periphery of meniscus and tied outside joint capsule.

Outside in, inside out, and all inside technique

Rehabilitation:•Patient’s who underwent partial meniscectomies can be allowed immediate wt bearing,range of motion exercises,functional strengthening and quick returns to daily activities•Presence of degenerative changes slows recovery and return to full activity must be individualised

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