Knee Pain Flashcards
Differential Diagnosis of Knee Pain by Location
Anterior
Injury to quadriceps, patella, or patellar tendon, plica syndrome, patellofemoral pain syndrome, severe OA, prepatellar bursitis, RA, gout, pseudogout, septic joint
Differential Diagnosis of Knee Pain by Location
Lateral
Lateral meniscal tear, LCL injury, iliotibial band syndrome
Differential Diagnosis of Knee Pain by Location
Medial
OA, anserine bursitis, MCL injury, medial meniscal tear, tibial plateau fracture, pica syndrome.
Differential Diagnosis of Knee Pain by Location
Popliteal
Effusion, popliteal/Baker cyst, DVT.
History
Trauma or constitutional sx, location of pain, acute/chronic, provocative/palliative factors, orthopedic hx, swelling, stiffness, instability, catching, popping, snapping sensation, sensory/motor changes; have pt point to area of pain w/one finger
Red Flags
pain after trauma, constitutional sx, disabling pain
General Exam
Examin both knees (uninjured as control), hip and ankle; observe gait, squat, duck waddle (squats and moves forward; test quadriceps and hamstring strength.
Inspection
Joint architecture, erythema, swelling, effusions.
Palpation
Warmth (nl knee is cooler than anterior shin), vascular exam, tenderness to palpation (patella, tendons, lateral & medial joint lines, anserine bursa), pain w/lateral displacement of patella (patellofemoral syndrome).
Range of Motion
Active and passive extension, (0-135degrees nl), varus & valgus instability at 0degrees for LCL & 30degrees for MCL; crepitus.
Initial Workup
Start w/radiograph; MRI to evaluate meniscal or ligament tear if dx unclear; if constitutional sx consider CBC, ESR, CRP; U/S if popliteal cyst suspected.
Ottawa knee rule
Plain films after acute injry to r/o fracture if any of the following:
>55y Isolated patellar tenderness Tenderness at head of fibula Cannot flex to 90 degrees Cannot bear weight for 4 steps immediately after injury and in ED
Sensitivity 98.5%
Specificity 48.6%
Communication w/Radiologist
Interpretation of imaging may be improved when PCP’s communicate where the pain is when requesting imaging.
Lachman test
ACL
87% sensitive, 93% specific
L hand on femur grasped just above the knee, R hand on the tibia, apply slight flexion; pull sharply toward your abdomen w/R hand while stabilizing wthe L hand; muscles must be relaxed; + for ACL injury if tibia feels unrestrained during sharp pull
Posterior Drawer Test
PCL
51-86% sensitivity
Pt supine w/ knee flex to 90 degrees, stabilize foot by sitting on it, place hands around tibia w/ thumbs meeting along front; apply pressure backward in plane parallel to the femur; + for PCL injury w/ unrestrained backward motion