Knee Disorders

Question 1

Anterior Cruciate Ligament Tear

Answer 1

• Definition:
  
  • tear of the anterior cruciate ligament
• Mechanism:
  
  • deceleration, hyperextension, non-contact pivoting injury
• General Info:
  
  • Most common knee ligamental injury. 70% sports related & more common in females. Usually accompanied by a MCL or meniscus tear.
• S/sxs:
  
  • **Sudden onset
  • Knee pain associated with “pop” & swelling followed by hemarthrosis
  • may develop knee buckling, inability to bear weight
• PE:
  
  • Lachman test: most sensitive, knee placed at 20 degrees in supine & tibia is pulled forward to test laxity
  • Anterior Drawer Test: knee placed at 90 degrees while pt is supine & tibia is pulled forward to test laxity
  • Pivot Shift test: knee is internally rotated, valgus force is applied, & knee is slowly flexed
• Dx:
  
  • Xray: initial test to r/o fracture, usually only positive for effusion, segond fracture is pathognomonic for ACL tear (avulsion of lateral tibial condyle)
  • MRI: best test to access ACL tear
  • Unhappy triad: injury to ACL, medial collateral ligament, medial meniscus
• Tx:
  
  • **Most patients require surgery
  • non-operative: protected weight bearing, hinged knee brace, early gentle AROM, PT, NSAIDs
  • Surgery: ACL reconstruction (not repair)
    
    • → long rehab

Question 2

Posterior Cruciate Ligament Injury

Answer 2

• Definition:
  
  • tear of the posterior cruciate ligament. PCL is the primary restraint to posterior motion of the tibia
• Mechanism:
  
  • Direct anterior blow, fall on flexed knee, dashboard injury (anterior force to proximal tibia with knees flexed)
• S/sxs:
  
  • Posterior knee pain
  • Anterior bruising
  • Large effusion
  • instability bearing weight
• PE:
  
  • Posterior Sag: patient’s hip flexed to 90 degrees while examiner support leg under lower calf & looks for posterior sag of the tibia
  • Posterior Drawer Test: posterior translational movement of the tibia
• Dx:
  
  • MRI = best test to access PCL tear
• Tx:
  
  • *Most pts do NOT require surgery
  • Non-operative: RICE therapy, NSAIDs, knee immobilization
  • Surgery: may be necessary if acute or associated with multiple injuries

Question 3

Medial Collateral Ligament Tear

Answer 3

• MCL:
  
  • resists Valgus force on the knee
• Mechanism:
  
  • Lateral Trauma
  • MCL injury more common than LCL
• S/sxs:
  
  • localized medial knee pain, swelling, ecchymosis, stiffness
  • pain & laxity with valgus stress
• PE:
  
  • evaluate for associated injuries and assess stability
  • palpate for entire ligament, but most injuries occur at midpoint
  • apply valgus/varus stress
  • McMurry, Apley, Ober, Thessaly
• Dx:
  
  • MRI: can detect collateral ligament injuries & severity
  • Grading:
    
    • -Grade 1: stretch, no tear
    • -Grade 2: partial tear
    • -Grade 3: complete tear (unrestricted motion)
• Tx:
  
  • usually do not need surgery (instability is uncommon)
  • incomplete tear (grades 1-2): pain control, PT, RICE, NSAIDs, knee immobilization
  • complete tear (grade 3): surgical repair

Question 4

Lateral Collateral Ligament Tear

Answer 4

• LCL: resists varus force on the knee
• Mechanism:
  
  • medial trauma
• S/sxs:
  
  • localized lateral knee pain, swelling, ecchymosis, stiffness
  • pain & laxity with varus stress
• assess stability
• palpate for entire ligament, but most injuries occur at midpoint
• apply valgus/varus stress
• McMurry, Apley, Ober, Thessaly
  
  • Dx:
    
    • MRI: can detect collateral ligament injuries & severity
    • Grading:
      
      • -Grade 1: stretch, no tear
      • -Grade 2: partial tear
      • -Grade 3: complete tear (unrestricted motion)
  • Tx:
    
    • usually do not need surgery (instability is uncommon)
    • incomplete tear (grades 1-2): pain control, PT, RICE, NSAIDs, knee immobilization
    • complete tear (grade 3): surgical repair

Question 5

Meniscal Tear

Answer 5

• Definition:
  
  • tear of the medial or lateral meniscus. Menisci are fibrocartilaginous pads that function as shock absorbs between the femoral condyles & tibial plateau
• Mechanisms: Twisting Injury
  
  • Medial is more common than lateral because the lateral meniscus is smaller & less mobile
• S/sxs:
  
  • Popping, “giving way” during ambulation, climbing or descending stairs
  • locking or catching
  • Effusion after activities
  • Pain along the medial or lateral joint line worse with twisting or squatting
• PE:
  
  • Most common finding: joint tenderness over the medial or lateral joint line
  • McMurray sign: pop or click when the knee is flexed & then externally rotated & extended
  • Apley test: pt is prone with knee flexed to 90 degrees then rotate knee medially & laterally, check for pop/click/pain
  • Thessaly test: most sensitive, pain/locking at medial or lateral joint with patient standing on affecting leg, knee flexed to 20 degrees, twist side to side x 3 times
• Dx:
  
  • MRI: most sensitive & specific
  • Transverse tear = most amenable to repair because it has best blood supply
• Tx:
  
  • *May heal without surgery but follow closely
  • Non-operative: Abstinence from weight bearing, rest with knee flexion, ice, compression dressing, NSAIDs
  • Surgery: indicated if young patient, high energy injury, repeat injury, large effusion, mechanical symptoms, high demand occupation, failure to improve
    
    • arthroscopic repair: <3mm, stable, recent injury, young patient, later return to play
    • partial meniscectomy: > 3mm, mobile, old injury, older patient, sooner return to play

Question 6

Types of Meniscus Tears

Answer 6

• Bucket Handle Tear: A vertical longitudinal tear displaced into the notch
• Flap tear
• Transverse Tear
  
  • most amenable to repair because it has the best blood supply
• Torn Horn tear

Question 7

McMurray’s Test

Answer 7

Question 8

Apley Test

Answer 8

Question 9

Thessaly Test

Answer 9

most sensitive for meniscus tears

Question 10

Knee Dislocation

Answer 10

Emergent

• Mechanism:
  
  • high energy trauma associated with multi-ligament injuries
• Types:
  
  • anterior (most common), posterior, lateral, medial, rotational
• s/sxs:
  
  • Multidirectional instability
  • Gross deformity (but may spontaneously reduce before ED arrival)
• PE:
  
  • Thorough neurovascularexam!
    
    • → need to assess pulses, cap refill (assess for injury to popliteal artery)
• Dx:
  
  • Need a vascular study: assess the popliteal artery
• Tx:
  
  • Medical Emergency → limb-threatening
  • Immediate orthopedic consult for prompt reduction
• Complications:
  
  • Vascular: Popliteal artery injury
  • -Neurological: peroneal or tibial nerve injuries

Question 11

Knee Fractures Overview & Complications

Answer 11

• Overview:
  
  • usually caused by significant trauma. Need to evaluate displacement & articular surfaces accurately. May be a sign of soft tissue injuries
• Complications:
  
  • Compartment Syndrome

Question 12

Tibial Plateau Fracture

Answer 12

• Mechanism:
  
  • Fall (most common), valgus or varus stress, axial loading, direct trauma
• Location:
  
  • Lateral Plateau = most common
• S/sxs:
  
  • Knee pain & swelling
  • Hemarthrosis
• PE:
  
  • check for peroneal nerve injury (foot drop)
• Dx:
  
  • Xray: but may be challenging to see
    
    • CT: may be needed for further eval
• Tx:
  
  • Refer to Ortho
    
    • May need Open Reduction and Internal Fixation (if displaced or severe)
    • Non operative: non-weight bearing hinged knee brace
• Complications:
  
  • soft tissue injury: meniscal & ligamental tears lateral meniscal tears = most common)
  • -***Compartment Syndrome
  • -Post-degenerative arthritis

Question 13

Patellar Fracture

Answer 13

• Mechanism:
  
  • direct blow = most common (fall on flexed knee, forceful quadriceps contraction)
• Epidemiology:
  
  • most common in young patients
• S/sxs:
  
  • knee pain, swelling & deformity
  • Limited knee extension with pain
• Dx:
  
  • Radiography: Sunrise and lateral views
  • CT: may be needed for further eval
• Tx:
  
  • *Refer to Ortho
  • Stable Fracture: vertical split, extensor mechanism intact → can be treated nonoperatively
  • Unstable Fracture: transverse split, intra-articular, disrupts extensor mechanism, needs surgery (open reduction & internal fixation)

Question 14

Femoral Condyle Fracture

Answer 14

• Mechanism:
  
  • direct blow (significant force), axial loading (fall from height)
• S/sxs:
  
  • Knee pain & swelling
  • inability to bear weight
• Dx:
  
  • X-ray
• Tx:
  
  • immediate ortho consult
  • open reduction & internal fixation
• Complications:
  
  • peroneal nerve injury
  • popliteal artery injury

Question 15

Maisonneuve Fracture

Answer 15

• Definition:
  
  • spiral fracture of the upper third of the fibula with disruption of the distal tibiofibular syndesmosis & associated injuries (ie fracture of the medial malleolus, posterior malleolus, or rupture of the deltoid ligament)
• PE:
  
  • palpate the proximal fibula & medial ankle → especially when someone has rolled their ankle
• Dx:
  
  • Xray
• Tx:
  
  • unstable fracture → ortho consult

Question 16

Segond Fracture

Answer 16

• Definition:
  
  • avulsion fracture of the proximal tibial lateral plateau margin
  • associated with anterior cruciate ligament & posterolateral corner knee injuries

Question 17

Patellar Malalignment

Answer 17

• Definition:
  
  • patella is tilted laterally or predisposed to lateral subluxation
• S/sxs:
  
  • retropatellar pain exacerbated with stairs
  • pain with prolonged sitting
• PE:
  
  • Gait: patella pointed inward with knock-knee alignment
• Dx:
  
  • Radiography: lateral patellar subluxation or lateral patellar tilt
• Tx:
  
  • Exercises to strengthen quads, elastic braces, PT
  • Srugery

Question 18

Patellar Dislocation

Answer 18

• Mechanism:
  
  • valgus stress after twisting injury or direct blow
• Types:
  
  • lateral (most common)
• Can present as an obvious dislocation or transient dislocation with a spontaneous reduction
• S/sxs:
  
  • “pop” at the time of injury
  • acute hemarthrosis
  • loss of motion
• PE:
  
  • Apprehension sign: pt exhibits anxiety/forcefully contracts the quads when examiner pushes laterally
  • Obvious dislocation:
    
    • knee stuck in flexion with an unusual prominence of the medial femoral condyle (rare b/c patella usually reduces spontaneously)
• Dx:
  
  • Xray
  • MRI: can confirm transient patellar dislocation based on bone bruising patterns
• Tx:
  
  • Closed reduction: (if still dislocated) push anteromedially on the patella while gently extending the leg → post-reduction film
  • Protective brace, oral analgesics, ice, modified weight bearing

Question 19

Patellofemoral Pain Syndrome

Answer 19

• Definition:
  
  • constellation of problems characterized by diffuse, aching anterior knee pain that increases with activities that place additional loads across the patellofemoral joint. No clear trauma, malalignment or instability
• Etiology:
  
  • multifactorial, overuse & overloading of the patellofemoral joint
• Presentation:
  
  • adolescent female, recent increase in activity level
• Risks:
  
  • running, squatting, climbing stairs, dynamic valgus, females, foot abnormalities (pes planus→ flat feet), overuse or sudden increase in physical activity level, patellar instability,quad (VMO) weakness, hyperlaxity syndrome
• S/sxs:
  
  • Disabling anterior knee pain behind or around the patella, worsened with knee hyperflexion (squats, stairs)
  • Sense of instability or retropatellar catching sensation
• Pe:
  
  • Compression of the patella during knee extension will produce symptoms or anticipated pain
  • Patellar grind test: patient in supine position with knee extended, examinar displaces the patella inferiorly into the trochlear groove, asks patient to contract quads while examiner palpates patella → pain
  • Patellar instability test:
    
    • bend knee 20-30 degrees & place finger inside patella to see how far you can displace it laterally
• Dx:
  
  • good hx and thorough exam for dx
  • Xray: Merchant’s View
• Tx:
  
  • *usually self-limiting
  • Activity modification: no jumps, squats, or running
  • -PT: strengthen VMO
  • -Icing after physical activity & NSAIDs
  • -Brace/sleeve/tape: for patellar stabilization
  • -Arch Supports
  • *Refer if sxs do not improve (may need surgery)

Question 20

Iliotibial Band Syndrome

Answer 20

• Definition:
  
  • inflammation of the iliotibial band due to friction between the ITB and the lateral femoral epicondyle.
• Anatomy:
  
  • The IT band is a dense fibrous band of tissue that extends from the ASIS down the lateral thigh & inserts on the anterolateral tibia
• Pathophys:
  
  • excess friction between the IT band & the femoral condyle
• Risks:
  
  • runners & cyclists
• S/sxs:
  
  • Lateral knee pain (sharp, burning) worse with changes in terrain & relieved with rest
• PE:
  
  • Ober test: pain or resistance to adduction of the leg parallel to the table in neutral position
  • Noble compression Test: pain over the distal ITB especially at 30 degrees of knee flexion with pressure applied to ITB
  • Tenderness over the lateral femoral epicondyle.
• Dx:
  
  • negative xray to r/o other etiology
• Tx:
  
  • Conservative: NSAIDs, ice, avoid overuse, PT
  • -Corticosteroid injection
  • -Refractory: surgery

Question 21

Ober Test

Answer 21

Question 22

Patellar/Quadriceps Tendonitis

Answer 22

• Definition:
  
  • overuse or overload syndrome involving either the quadriceps tendon at its insertion or the patellar tendon at its insertion
• Risks:
  
  • young adults involved in jumping or kicking sports (“Jumper’s Knee”)
• S/sxs:
  
  • -Anterior Knee Pain (Hallmark) that begins immediately after exercise
  • -Exacerbated by climbing, descending stairs, running, jumping, or squatting
• PE:
  
  • Tender to palpation at the bony attachments of the quadriceps tendon or patellar tendon
  • Increased heat, mild swelling & soft tissue crepitus
  • Normal motion but painful
• Dx:
  
  • Xray: usually normal, but may show small enthesophytes (calcifications of the tendinous insertions)
• Tx:
  
  • Goals: rest & pain control, restoring pain-free range of motion/strength, resuming activities
  • Period of relative rest, NSAIDs, analgesic creams, Ice/heat
  • *patients with a possible rupture of the extensor mechanism require prompt referral to ortho

Question 23

Patellar/Quadriceps Tendon Rupture

Answer 23

• Definition:
  
  • rupture of the quadriceps or patellar tendon disrupts the extensor mechanism of the knee → inability to actively extend the knee fully.
  • Quads > Patellar.
• Cause:
  
  • Quadriceps: forceful quadriceps contraction (fall on flexed knee, walking up/down stairs)
  • Patellar: direct blow (MVA, fall from standing height)
• Risks:
  
  • males > 40yo, fluoroquinolones, endocrinopathy
• S/sxs:
  
  • **immediate onset
  • Sharp proximal knee pain & swelling after an acute injury
  • Sense of instability or “giving way”
• PE:
  
  • inability to extend knee & perform straight leg raise
  • Large effusion
  • Quads: palpable defect above the knee
  • Patellar:palpable defectbelow the knee
• Dx:
  
  • Lateral view xray of the knee
    
    • Quads: patella baja
    • Patella: patella alta
  • Triad:
    
    • -palpable defect
    • -inability to actively extend the knee
    • -patella alta or baja
• Tx:
  
  • **Prompt referral to ortho for surgery
  • Knee immobilizer, non-weight bearing, RICE
  • Surgical repair: within 7-10 days

Question 24

Knee Bursitis

Answer 24

• Definition:
  
  • chronic pressure/friction (overuse) → thickening of synovial lining → excessive fluid formation
• Causes:
  
  • chronic irritation, trauma to the knee (direct blow), direct penetration of bacteria
• Organisms:
  
  • S. aureus, Streptococcus species
• S/sxs:
  
  • knee pain & swelling
• PE:
  
  • inspect areas of swelling
  • observe gait
  • Septic Bursitis:
    
    • -increased pain, warmth, & erythema
    • -Fever, elevated WBC
• Dx:
  
  • Xray to r/o bony conditions, show diffuse anterior soft-tissue swelling
  • Synovial fluid aspiration: to r/o septic arthritis
• Tx:
  
  • Non Infection: NSAIDs, ice, activity modification, corticosteroid injection
  • Infected: oral antibiotics (IV if severe), possible drainage & excision of the bursa
• Complication:
  
  • septic bursitis may result in chronic drainage or spread to the knee joint

Question 25

Shin Splints

Answer 25

• Definition:
  
  • characterized by the gradual onset of pain the posteromedial aspect of the distal third of the leg. Develops as a response to increased exercise or activity level → inflammation of the tibial periosteum.
• S/sxs:
  
  • Pain in distal third of medial tibia that develops gradually with exercise
• PE:
  
  • Tenderness along the posterior medial crest of the tibia in the distal third of the leg
  • Pain with resisted plantar flexion
• Dx:
  
  • **Need to r/o stress fractures & compartment syndrome
  • Xray: to r/o stress fracture
• Tx:
  
  • Limit activity to soft surface, decrease training, avoid hills
  • NSAIDs, ice, analgesic creams

Question 26

Stress Fractures

Answer 26

• Definition:
  
  • hairline or microscopic break in bone caused by microtraumatic, cumulative overload on bone
• Risks:
  
  • OVERTRAINING, hormonal imbalance, poor nutrition, vitamin D deficiency, osteoporosis
• S/sxs:
  
  • focal area of pain of the tibia/fibula in association with exercise → pain at rest
• PE:
  
  • Tenderness localized to affected area of bone
  • Bony callus may be palpable if 6+ weeks since onset
• Dx:
  
  • X-ray: stress fractures may not be visible until 3+ weeks
  • Bone scan or MRI may be needed to confirm
• Tx:
  
  • Period of rest, fracture braces
  • **Difficult to treat a fatigue fracture of the cortex of the midshaft of the tibia “dreaded black line” → not a ton of vasculature so difficult to heal
• Complications:
  
  • Continued activity → displaced fracture

Question 27

Osgood-Schlatter’s Disease

Answer 27

• Definition:
  
  • inflammation of the patellar tendon at the insertion of the tibial tubercle.
• Etiology:
  
  • overuse or small avulsions from repetitive knee extension & quadriceps contraction
• Risks:
  
  • 10-15 yo males, during growth spurts, athletes
• S/sxs:
  
  • Anterior knee pain & swelling worse with activity, relieved with rest
• PE:
  
  • prominence, swelling, & tenderness to the anterior tibial tubercle
• Dx:
  
  • Imaging not needed in classic presentation (bilateral)
  • Xray: may be normal; elevation, ossification, &/or bone fragmentation of the tibial tuberosity
• Tx:
  
  • **Resolves in 12-24 months
  • Conservative: avoid provocative activities, RICE, NSAIDs, quadricep stretching
  • Surgery: if refractory, after growth plate closure