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
McMurray test
53-97% specific
Tests for meniscal injury; place left hand on medial joint line w/ knee fully flexed; w/ right hand evert foot. apply valgus stress & gently flex & extend knee; + test w/ clicking around medial joint line.
Patellofemoral syndrome (Runners knee)
most common cause of knee pain in primary care,
Pts typically female, <45, p/w pain, popping/clicking/snapping going up/down stairs, rising from seated position, while running, or after prolonged sitting
Exam: Tenderness over patellofemoral joint or behind patella, reproduced on compression of patella against femur; dx of exclusion
Patellofemoral syndrome (Runners knee)
Treatment
Rest, Ice, NSAIDs, PT, stretching, wt loss, quadriceps strengthening (stationary cycling), consider foot orthoses, orthopedic referral if refractory.
Osteoarthritis History
Pain w/activity & relieved by rest, decreased ROM, gelling/stiffness w/inactivity, slowly progressive, crepitus, medial pain prominent.
Osteoarthritis
Diagnostic Criteria
Knee pain +3 of the following: age >50y, morning stiffness <30min, crepitus, bony tenderness, bony enlargement, no palpable warmth
Osteoarthritis
Treatment
Wt loss (if overweight), physical therapy, APAP.
Anterior Cruciate Ligament Injury
Trauma ->pop, immediate pain, swelling, mexhanical sx; + Lachman test, tear visible on MRI; pt cannot squat/duck waddle.
Females at increase risk
ACL injury increases risk of OA
Anterior Cruciate Ligament Injury
Treatment
Rest, ice, elevation, APAP, compression, PT; ortho referral if pt young, has significant instability, wishes to return to vigorous activity, or s/sx of other joint damage; rehabilitation + early ACL reconstruction = rehabilitation +/- delayed ACL reconstruction.
Bursitis
Local pain on rest & motion; anserine bursa is medial & 6cm below joint line; pain typically at night; prepatellar bursa is anterior & between patella & skin; inflammation caused by trauma/repetitive kneeling
Bursitis
Treatment
Compression dressing/braces/knee pads, NSAIDs, ice, PT; chronic bursitis may respond to steroid injections, aspiration
Iliotibial Band Syndrome
Lateral aching/burning/stinging where the iliotibial band traverses the knee, esp over the lateral femoral condyle, often seen in runners, cyclists; pain may radiate to hip; Ober test assesses strength of iliotibial band
Ober test
Pt lying on side with test side up. The knee can be flexed to 30-90 degress with the hip in slight extension. The leg is abducted and then allowed to lower to position.
Normal if leg is allowed to fall back down
Positive if leg is not able to return to neutral
Normal
Iliotibial Band Syndrome
Treatment
Ice, NSAIDs, stretching, temporary avoidance of activities that increase pain; steroid injections or surgery for cases refractory to conservative tx
Gout/Pseudogout
Other joints affected, joint swollen/tender; often with effusion; crystals in joint aspirate
MCL injury
Medial knee pain, pain with walking, twisting, pivoting; typically injured after twisting or hyperextension of the knee.
MCL injury
Treatment
Rest, ice, compression, elevation, joint protection; ASA, NSAIDs, early mobilization as tolerated; ortho referral if knee unstable or pain/disability persists.
Meniscal injury
Often asymptomatic, but can p/w mechanical sx (buckling, locking), tenderness over joint line, pain w/twisting, + McMurray’s; commonly occurs when knee twists w/foot locked on ground; pt cannot duck waddle, tear seen on MRI.
Meniscal Injury
Treatment
Rest, avoid activities that cause pain, ice, crutches, patellar brace, PT; persistent pain may require open/arthroscopic pain.
Plica Syndrome
Irritation/injury, of the plica, a component of synovial tissue -> medial knee pain & popping sensation with flexion in runners/athletes or after trauma; pain increases with flexion of knee or sitting.
Plica Syndrome
Treatment
Rest, ice, stretching, NSAIDs, PT; Arhtroscopic surgery may be curative.
Popliteal cyst
cyst in popliteal fossa due to increase pressure in joint secondary to joint disease (OA, RA, meniscal injury); mass in popliteal fossa decreases with flexion at 45 degrees.
Stress fracture
Pain after an increase in activity; activity worsens pain, relieved by rest; may not be visible on plain film in 1st 2 weeks, but may be seen on MRI.
Stress Fracture
Treatment
Avoid activities causing pain, APAP, bracing, shoe inserts for cushioning, calcium/vitamin d supplementation, PT: high-risk fractures (patella, anterior tibia) should be referred to ortho.
Tendinitis
Pain going up/down the stairs, commonly seen in runners.
