· meniscus torn by rotational force incurred while joint partially flexed and moving to extended position
· meniscus caught between femoral and tibial condyles
· usually
· valgus and external rotation
· varus and internal rotation
· medial meniscs more commonly injured
· ratio of 5:1 (now thought to be 2:1)
· less mobile
· most commonly posterior horn
· most common
· vertically oriented tear parallel to edge of meniscus
· usually of posterior part of meniscus
· may occur in either meniscus
· extent varies
· incomplete (usually of inferior surface)
· complete
· bucket handle (inner fragment displaces over intercondylar notch)
· may be central or peripheral
· more common in older patients
· horizontal cleavage plane between superior and inferior surfaces of meniscus
· occur more commonly in posterior half of medial meniscus or mid-segment of lateral meniscus
· vertically oriented full-thickness tear running obliquely from inner edge of meniscus out to body of meniscus
· if base posterior, referred to as posterior oblique tear and vice versa
· vertically oriented full thickness tear extending from inner edge of meniscus radially to periphery
· may be incomplete (not to periphery) or complete (to periphery)
· parrot beak tear is incomplete radial tear with anterior or posterior extension
· similar to oblique tears
· have horizontal cleavage element
· elements of all above
· usually in longstanding meniscal lesions
· complex tear of degenerative meniscus
History of injury
· usually of weight bearing twist
· may not be specific injury (esp. in middle-aged patient)
· associated swelling usually delayed (6 hours) and mild to moderate
Locking
· only with longitudinal tears, esp. bucket handle tear of medial meniscus
· locking may also occur with osteocartilagenous loose body
· false locking
· occurs after injury
· haemorrhage around posterior capsule leads to hamstring spasm
· result is inability to completely extend knee
Giving way
· may occur with other knee disorders
· loose bodies
· instability
· quadriceps wasting
· when due to meniscal tear, usually occurs with rotatory movements
· feeling of subluxation or 'jumping out of place'
Swelling
· due to effusion
· effusion indicates synovial irritation
· may be due to number of causes other than meniscal pathology
· repeated displacement of torn meniscus may lead to sufficient synovial irritation to produce recurrent or chronic effusion
· absence of effusion is non-diagnostic
Effusion
· as above
Tenderness
· along periphery of meniscus
· usually posterior
· due to synovitis of adjacent capsule
Special tests
· numerous
· involve attempts to locate and reproduce crepitation that results as knee is manipulated
· useful but not diagnostic
McMurray test
· probably best known
· to check medial meniscus
· patient supine
· knee forcibly flexed
· posteromedial joint line palpated with one hand
· other hand grasps foot
· leg maximally externally rotated
· knee slowly extended
· as femur passes over tear, click palpated or heard
· click causes pain
· to check lateral meniscus
· posterolateral joint line palpated
· leg internally rotated
Apley grind test
· patient prone
· knee flexed to 90 degrees
· thigh fixed against couch
· foot and leg pulled upward and rotated to put rotational strain on ligaments
· pain produced if ligaments damaged
· then foot and leg pressed downward and rotated as knee slowly flexed and extended
· pain localised to joint line suggests meniscal tear
· performed routinely
· AP, lateral, intercondylar and skyline, and standing AP if over age 40
· will not demonstrate torn meniscus
· performed to exclude osteochondral loose body, OCD and other internal derangements
· gold standard in past
· involves injection of air and radiopaque dye into knee
· multiple x-rays taken in various positions
· studies report 95% accuracy on medial side and 85% accuracy on lateral side
· disadvantages are
· invasive
· high x-ray exposure
· interpreter dependent
· not routinely used by most surgeons
· may occasionally be useful where diagnosis difficult and surgery relatively contra-indicated
Technique
· images
· coronal T1 weighted
· sagittal and coronal T2 weighted
· meniscal signal graded 1 - 3
· grade I signal is increased signal within the meniscus
· grade II signal is linear and may or may not communicate with the capsuler margin but does not communicate with the articualr surface
· grade III extends to the articualr surface and when sharp, linear and birght it most often represents a tear
Efficacy
· positive predictive value of 75%
· negative predictive value of 90%
· sensitivity of 80%
· specificity of 70%
· accuracy of 80%
Advantages
· noninvasive
Disadvantages
· expensive
· most surgeons inexperienced in interpretation
· cannot treat lesion cf. arthroscopy
Associated lesions
· perimeniscal cysts
· menisco-tibial separation
Difficulties
· meniso-tibial attachments
· ligaments of Wrisburg + Humprey
· transverse ligament
· popliteus tendon sheath
· has become mainstay of diagnosis when tear clinically suspected
· lesions that are detected can be treated at the same time
· joint surface contact on torn meniscus will produce articular cartilage damage
· removal of meniscus will lead to joint instability and altered biomechanics with maybe greater degenerative changes
Indications
· suspected tears that cause infrequent and minimal symptoms
Contraindications
· symptoms that continue or worsen
· chronic tears with superimposed acute injury
· locked knee from a bucket handle tear
Technique
· restoration of ROM
· quadriceps exercises
· exercises for hamstrings and hip muscles
Indications
· almost daily symptoms
· frequent locking
· repeated or chronic effusions
· acutely locked knee
Options
· left
· excised
· repaired
· partical thickness tears
· full thickness tears that are
· stable
· < 5 mm
· historically, total exision of torn meniscus advocated
· studies have shown
· degenerative changes (caused by biomechanical changes) are directly proportional to the amount of meniscus resected
· significant difference in degree of osteoarthritic change long term between total and partial meniscectomy
· timing of surgery has little effect on eventual degenerative changes
· small tears 5-7 mm
· irrepairable tears > 5 mm from periphery
· degenerative tears
· rarely performed
· indicated where
· associated injuries require open repair at the time
· arthroscopic equipment or expertise not available
Types
Partial meniscectomy
· only the loose unstable meniscal fragments are excised
· stable meniscal rim preserved
Subtotal meniscectomy
· type and extent of tear necessitates exision of portion of rim
· usually of posterior horn
Total meniscectomy
· required when meniscus detached from peripheral attachment and intrameniscal tears present
Partial meniscectomy
Technique
· tear carefully assessed and probed
· allows nature of excision to be formulated before proceeding
· pathological tissue excised
· preferably en bloc
· may have to be morsellised
· peripheral rim tidied and checked for stability
· joint irrigated to remove debris
· quads strengthening started immediately (SLR)
· ROM started next day
· weight bearing and return to activities determined symptomatically
· increase in forces across joint directly proportional to amount of meniscus excised
Total meniscectomy
· 40% incidence XR changes of degenerative changes at 15 yrs
· 6% incidence on contralateral knee
Partial meniscectomy
· 95% good results at 2 1/2 years if no evidence of degenrative changes at time of surgery
· falls to 80% if degenerative changes present
· horizontal or complex tears associated with a poorer outcome
· regaining popularity with increasing awareness of importance of menisci
· shown that peripheral 1/3 to 1/4 of meniscus is vascular enough to provide granulation tissue that results in healing
· high rates of success reported
· most tears in children and adolescents are conducive to healing
· well-performed repair now accepted to be far superior to any degree of meniscectomy
· diminished success in unstable knees
· in combined meniscus and ACL injuries, 60% healing with isolated repair and 90% healing if combined ACL reconstruction
· only 10-15% of tears amenable to repair
Tear
· within 5 mm of periphery
· within 3 mm definitely vascular
· within 3-5 mm is grey zone
· of traumatic origin
· vertically and longitudinally orientated
· significant (unstable and > 7 mm long)
· minimal meniscal body damage
Patient
· young patient
· AND prepared to comply with postop restrictions
· proponents of both open and arthroscopic repair
Principles
· tear debridement and local synovial, meniscal and capsular abrasion to stimulate proliferative fibroblastic response
· suture placement to reduce and stabilise meniscus
· postoperative immobilisation in 30o flexion for 6 weeks
· fibrin clot may be used to enhance healing
Aftercare
· crutches with touch weight bearing for 6 wks
· may use hinged splint to limit ROM
· locked for 1st 2 wks
· 30o-70o for next 2 wks
· discard for last 2 wks
· limitation to low-impact activities for next 6 wks
· lateral meniscus - common peroneal nerve
· medial meniscus - saphenous vein
· survival
· 90% at 5 yrs
· 80% at 10 yrs
· less satisfactory with unstable knee (usually ACL)
· 60% at 5 yrs
· 50% at 10 yrs
· protective against OA
· incidence of 15% with repair cf. 60% with meniscectomy
· meniscus is round rather than cresenteric
· occupies more than 70% of tibial surface
· 90% occur on lateral side
· uncommon
· usually in children and adolescents (age < 15)
· reported that the lateral meniscus is never discoid during normal development
· discoid shape develops because of hypertrophy of posterior horn due to excessive motion because of its lack of normal fixation
· pain is commonest complaint
· followed by
· clicking over lateral side
· rucurrent effusions
· locking
· usually unremarkable
· by Watanabe
· entire articular surface of tibial plateau covered by thickened abnormal meniscus
· variable intermediate portion between horns
· large posterior horn with no definite attachment to tibial plateau
· entire posterior portion hypermobile
· widened jt space
· tilted plateau
· proximal fibula head
· flattening of lateral femoral condyle
· hypoplasia of lateral tibial spine
· with contouring of the remaining meniscal rim
· indicated in
· slight degeneration or minimal tear
· no abnormal thickening
· not of the Wrisberg type
· no hypermobility
· intact capsular attachment
· all other cases
· most common in lateral meniscus
· 9:1
· peak incidence is age 20-40
· previously thought to be
· mucus-producing synovial cells incorporated into meniscus
· mucoid degeneration of meniscus
· probably due to infiltration of joint fluid into extra-articular tissues
· almost associated with horizontal cleavage tear
· usually present with pain
· intermittent ache
· activity related
· may notice lump
· may vary in size in relation to degree of activity
· lateral mass associated with lateral joint line
· maybe slightly superior
· usually anterior to LCL
· best seen with knee in slight flexion
· usually firm and immobile
· ganglion
· calcific deposit in collateral ligament
· osteochondroma
· soft tissue tumour
· arthroscopic resection of tear
· tear may be difficult to identify
· identified with careful inspection and probing
· often on undersurface of meniscus
· forceps passed through tear into cyst
· usually results in decompression of cyst
· good pain relief
· minimal recurrence of symptoms