Knee Pain

Samuel Lazaroff and Devon Shannon

Background 

  • Key features of the history include:
    • Location: Have pt point to the area that hurts most
    • Weight bearing, systemic symptoms (e.g. fevers)
    • Specific activities that worsen pain: Squatting, twisting, stair climbing
    • Trauma and mechanism of injury
      • High-energy trauma: high risk of bony and/or ligamentous injury
      • Low-energy trauma and atraumatic etiologies organized by location (see table)
    • Presence/absence of effusion and swelling
    • History of prior trauma to the knee

Knee Location

Low-Energy Trauma

Atraumatic
Anterior

Patellar subluxation or dislocation (instability)

Patellar fracture

Patellar tendon rupture

Quadriceps tendon rupture

Tendinopathy: patellar or quadricep

Hoffa’s fat pad syndrome (inflammation of post-patellar fat)

Prepatellar bursitis

Patellofemoral pain syndrome

Chondromalacia patella

OA
Medial

MCL tear

Acute medial meniscus tear

Medial meniscus degenerative tear

Pes anserine bursitis

OA
Lateral

LCL tear

Acute lateral meniscus tear

IT band syndrome

Lateral meniscus degenerative tear

OA
Posterior

PCL tear

Hyperextension

Baker’s cyst

Popliteal a. aneurysm/entrapment
Generalized

ACL tear

PCL tear

Intra-articular fracture

Patellofemoral pain syndrome

Patellar stress fracture

Referred from hip or ankle

OA

Presentation 

  • Patellofemoral pain syndrome: anterior pain worse with stair climbing
  • Patellar tendonitis: anterior pain worse with jumping
  • IT band syndrome: lateral pain worse with walking/jogging, but better with running
  • Bursitis: pain at location of bursa
  • Traumatic effusion
    • Consider ACL (usual acute ~hrs) or PCL rupture, meniscus tear (usually within 24hrs), patellar instability (dislocation of subluxation), bone bruise, fracture
  • Atraumatic Effusion:
    • Activity related: consider osteoarthritis or osteochondral injury
    • Non activity related: autoimmune, crystalline arthropathy, Lyme disease, septic arthropathy (including gonococcal)
    • Less common causes: primary bone tumor, viral infection (Parvo), hyperparathyroidism, hemochromatosis, syphilis, sarcoid, Whipple’ 
      ** Edema in patient with TKA can indicate hardware failure; refer to surgeon **

Evaluation 

  • Physical Exam
    • Gait
    • IPASS: Inspection, palpation, active/passive ROM, strength, special tests (see below)
    • Check for effusion with milk maneuver, balloting
    • Neurovascular exam including reflexes if applicable o Examine the back, hip, and ankle PM&R 481
  • Aspirate if effusion present and no clear diagnosis or concern for septic joint (order cell count with diff, crystal analysis, +/- gram stain and culture)
  • Ottawa Knee Rule = Imaging if 1 of following:
    • > 55 y/o
    • Isolated tenderness of patella
    • Tenderness of fibular head
    • Unable to flex 90° º
    • Unable to ambulate 4 steps at time of injury and at time of evaluation

Provocation Tests of the Knee

Test

Isolates

Action

Positive if
Anterior Drawer ACL Hip flexed and knee in 90° of flexion, pull anteriorly on tibia Tibia translates forward
Pivot Shift ACL With knee extended, internally rotate the foot and apply valgus force Translation of femur or tibia
Lachm ACL With knee flexed 20°, hold thigh down with one hand while pulling anteriorly on tibia with your other hand (with thumb on tibial joint line) Soft end point of tibial translation
Posterior drawer PCL With hip flexed and knee in 90° of flexion, push posteriorly on tibia Tibia translates backwards
Varus stress LCL With knee flexed at 30°, apply varus stress Pain and laxity laterally
Valgus stress MCL With knee flexed at 30°, apply valgus stress Pain and laxity medially
Joint line tenderness Meniscus Palpate Reproduces pain at site
McMurray Meniscus With hip & knee flexed, apply:
Medial: valgus force and internal rotate foot
Lateral: varus force and externally rotate foot		 Click, pop, or reproduces pain
Thessaly Meniscus With pt standing on 1 leg flexed ~30°, have pt rotate medially and laterally on planted knee Click, pop, or reproduces pain
Noble Compression IT band Pt lies on unaffected side, flex knee to 90° while pressure applied to distal IT band (lateral epicondyle) Click, pop, or reproduces pain
Patellar compression Patellofemoral pain With knee extended and quads relaxed, apply direct pressure to anterior patella as pt tightens quads Reproduces pain
Patellar apprehension Patellofemoral pain With knee flexed to 30°, displace patella laterally Pt grimaces or tries to straighten leg

Imaging 

  • X-ray: AP, lateral, and sunrise view (best for patellar).
    • OA hallmarks: Subchondral sclerosis, osteophyte, joint space narrowing, bone cyst
    • Obtain in standing position or else joint space narrowing may not be apparent
  • MSK U/S: Allows for dynamic imaging. ~100% sensitive for effusion and can visualize ligaments, muscles, tendons, joint space, and vasculature
  • MRI: indicated after failure of conservative management or when considering surgical repair (e.g. concern for ligament tear in primarily young active individuals)

Treatment 

  • RICE (rest, ice, compression, elevation) for acute injuries
  • Bracing is good for kinesthetic reminder and stability
  • NSAIDs, topical Diclofenac, antibiotics if effusion or bursa tapped indicates infection
  • PT for 4-6 weeks for OA, ligamentous, muscular, or meniscal injury
  • Referral to Sports Medicine or PM&R for non-operative interventions such as corticosteroid injections or viscosupplement injections
    • Surgery typically reserved for young, active individuals with ligamentous injury
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