Meniscus and ligament knee injuries
General
- torn menis or lig can cause sig disability- so expeditious repair needed
- knee largest articulating joint in body- is modified hing with extensive ROM
- stability provided by sof tissue- cruciate ligs and collateral
ligs, menisci, capsule and muscles
- acl and pcl add stability and proprioception
- ligs passively limit motion therfore providing stability
- acl- pcl limit ant and post desplacement of tibia on femur respectivelly
- acl limits ant motion of tibia on femur- if tibial plateau keeps
going forward get relative int rotation of tibia at terminal extention
and can result in sensation knee is buckling or giving out- most
common during pivoting.
- acl inj also gives "loss of confidence" due to lack of proprioception input.
- pcl provides stability regardless of position of knee- if
disrupted, tibia goes posteriorly- may get hyperextension of knee,
post displacement of tibial during flexing and varus and valgus
angulation with knee extenstion.
- symptomatic pcl inj more common in pt with chronic tear or acute
tear with other lig inj
- Meniscus- increase joint stability, nutrition, lubrication, shock
absorption or articular cartilage.
- lat meniscus larger and less firmly attached- more mobile
- medial menis immobilie and attached to MCL and capsule
- med menis greater chance of inj since bears more weight and immobile
- knee flexion pushes menisc posteriorly
MECHANISMS OF INJ
- position of knee at time of inj dictates which structures inj
- acl- inj during traumatic twisting with valgus stress- may hear pop
- pcl- foot planted, twist with force directed posteriorly against
tibia with knee flexed
- col lig- from abduction and ext rotation
- with age menisc tissure degenerates and splits and get horizontal
tears- this leads to more loads on articular cartilage and arthritis.
- menisc are without pain fibres so pain from tearing and bleeding
into perif attachments and capsule that causes pain.
- locked knee in flexed position by bucket handle tear in mcl- more
common in youger pt
- lcl more mobile so less locking when torn- may get clicking
- women have more acl inj than men
Diagnosis
- examine healthy knee first- relaxes pt and ensures trust. also
needed for comparison
- inspection- gait- effusion
- palpation- warmth, eff, swelling, crepitance
- function- ACL tests- lachman, ant drawer and lat pivot shift- should
not cause pain in subacute setting
Lachman- pt supine, knee 20- 30' extended- hold dista femur with one
hand and prox tibia with other and pull up- should feed discreet stop-
is positive test if no stop felt or too much motion
Ant Drawer- pt supine, knee flexed 90', pull up on prox tibia
Lateral Pivot Shift- valgus stress to knee with twisting force while
flexing knee. one hand on lat part of knee pushing in. other hand on
foot with lateral force. As start to extend knee, will get thud or
jerk at 10- 20' representing ant subluxation of tibia on femur
- pcl stability assessed by post drawer test- pt supine, both knees
flexed 90'. In knee with pcl tear tibia will sag posteriorly. If
putting force on post calf corrects sag is positive test.
Meniscal integrity- mcmurray, apley, med- lat gring
McMurray- pt supine, one hand on foot, other gives valgus force to
knee- extend knee and int and ext rotating tibia. Positive if get
popping, sensation of symptoms along joint line and inablity to extend
knee fully.
Apley Compression test- pt prone, put your knee on pts thigh and flex
knee and ext rotate tibia- then compress tibia downward- if more pain
is postive
Medial Lateral Grind- supine, cradle calf in one hand. other on tibial
joint line- apply varus and valgus stresses during flex and extending
knee. if get grinding sensaiton from hand on joint line if positive
RESULTS
- composite test of acl, pcl meniscus reasonable sens and specific.
acl/ pcl test better predictors than menisc tests.
- no data to judge test for mcl/ lcl inj
Source
6/06 MISTRY