15Screw Home MechanismLocking mechanism as the knee nears its final extension degreesAutomatic rotation of the tibia externally (approx. 10 degrees) during the last 20 degrees of knee extensionFemoral condyles are a different sizeMedial has larger surface areaThe tibia glides anteriorly on the femur. As knee extends, the lateral femoral condyle expends its articular distance. The medial articulation continues to glide, resulting in external rotation of the tibia utilizing the lateral meniscus as the pivot point.ACL & PCL are rotary guidesForms a close-packed position for the knee joint
16History MOI - Previous history Pain (levels, types, descriptors) Position of lower extremity at time of injury (?foot planted, knee extended)Previous historyPain (levels, types, descriptors)Unusual sounds/sensations “pop, clicking, snapping”Chronic vs. acuteLocation of pain “inside the knee”SurfaceShoesType of activity at time of injuryPainful to walk up/down stairs; any clicking, catchingDid it swell immediately, slowly?Is the swelling located in the knee or in a pocket?
17Observation Bilateral comparison Gait (limp, walking on toes, do they not want to extend knee, do they keep the knee stiff)Swelling (girth measurements)DiscolorationDeformity (squinting patellae, “Frog-eyed” patellae, Patella alta, Patella baja)Genu valgum, genu varum, recurvatumMusculature – defined/mushy
18Q-angleThe quadriceps angle (Q-angle) is the angle formed between a line drawn through the tibial tuberosity and the center of the patella and another line drawn from the anterior superior iliac spine (ASIS) of the pelvis through the center of the patella.
21Stress/Special Tests On-field vs. Off-field eval Check for fractures, blood, deformities, neurologicalValgus Stress Test – MCLVarus Stress Test - LCLLachman’s – ACLAnterior Drawer – ACLMcMurray’s - meniscus
22Anterior Drawer Test(+) Test is increased anterior tibial translation over 6 mm(+) test indicates:ACL (anteromedial bundle)posterior lateral capsuleposterior medial capsuleMCL (deep fibers)ITBArcuate complexFalse (-) if only ACL is tornFalse (-) if there is swelling or hamstring spasmFalse (+) if there is a posterior sag sign present
23Lachman’s Test Best acute ACL test Best on field test (+) test is a “mushy” or “empty” end-feelFalse (-) if tibia is IR or femur is not properly stabilized
24Posterior Drawer Test Tests for posterior instability Make sure that there is no anterior translation prior to performing test(+) Test indicates:PCLArcuate ComplexPossibly ACL ???Rubenstein, et al 1994 found posterior drawer test 90% sensitive for PCL injury (versus 58% for Quadriceps Active Test & 26% for Reverse Pivot Shift Test). Clinical exam on whole was 96% effective in detecting PCL dysfunction
25Godfrey’s Test Tests for posterior cruciate ligament damage (+) test is a posterior displacement of the tibial tuberosity
26Valgus Stress Test (+) Test in 30° Grading Sprains Assesses medial instabilityMust be tested in 0° and 30°(+) Test in 0°MCL (superficial and deep)Posterior oblique ligamentPosterior medial capsuleACL/PCL(+) Test in 30°MCL (superficial)PCLGrading SprainsMiller et al 1998 used MRI to evaluate 65 patients with Grade III MCL sprains & found 45% also suffered bone bruising or microfracture.Bone injury with Grade III MCL is 50% as common as with Grade III ACL.McClure et al 1989 found poor intertester reliability on valgus stress test at 0 and 30 degrees using 3 PT to evaluate 50 patients
27Varus Stress Test Assesses lateral instability Must be tested in 0° and 20/30° flexion(+) Test in 0°LCLPosterior Lateral CapsuleArcuate ComplexPCL/ACL(+) Test in 30°Posterior lateral capsuleArcuate complexGrading Sprains
28Apley’s Distraction Test Tests for meniscal or ligamentous lesions(+) test is pain that is eliminated (meniscal injury), or pain that is increased (ligamentous)
29Apley’s Compression Test Tests for meniscal lesions(+) test is increased pain during compression which may increase with rotation in either direction
30Stress/Special Tests Check for swelling Check ROM Ely’s Test Sweep Test, Ballotable PatellaCheck ROM Ely’s TestCheck integrity of ligaments & joint stabilityValgus, Varus, Lachman’s, Anterior/Posterior Drawer, Godfrey’s Test, Posterior Sag Test, Crossover Test, Slocum Drawer Test, External Rotation Test, Pivot ShiftCheck integrity of meniscusMcMurray’s, Apley’s Compression/Distraction, Duck Walk, Bounce homeCheck integrity of patellaPatellar Apprehension, Q Angle, Clarke’s Sign, Patellar glide, tilt, rotationCheck integrity of Iliotibial BandOber’s Test, Noble’s Compression Test