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Orthopaedics & Rheumatology > The Knee > Flashcards

The Knee Flashcards

1
Q

Knee Joint

A
  • Largest joint in the body
  • Hinge joint
  • Main movement = flextion/extension
  • Actually two joints
    • tibiofemoral joint
    • patellarfemoral joint
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2
Q

Femur

A
  • Strongest and largest bone in the body
    • Enlarged femoral condyles articulate with the tibial plateau
    • Articulates: tibial plateau, posterior patella
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3
Q

Tibia

A
  • Medial bone of the leg
  • Median and lateral condyles (aka plateaus) serve as receptors for femoral condyles
  • Bears most of the weight
  • Tibial tuberosity
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4
Q

Fibula

A
  • Lateral bone of the leg
  • Does not articulate with the femur or patella
  • Attachment for:
    • biceps femoris
    • lateral collateral ligament
  • Non-weight bearing bone
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5
Q

Patella

A
  • Triangular shaped bone
  • Articulates with femur
  • Considered a sesamoid bone
  • Imbedded in quadriceps and patellar tendons
  • Mechanism:
    • acts as a pulley, improving the angle of pull
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6
Q

Q-angle

A
  • Angle between the ASIS to the middle of the patella and a line from the tibial tuberosity
  • No evidence that increased Q-angle is a risk factor for patellofemoral pathology
  • Men tend to have a smaller angle than women
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7
Q

Bony Landmarks to Know

A
  • Superior & Inferior Patellar Poles: top and bottom of patella –> tendonitis
  • Tibial Tuberosity: attachment of patellar tendon
  • Gerdy’s Tubercle: lateral IT band attaches here
  • Medial & Lateral femoral condyles: often fractured
  • Prox anterior medial tibial surface: bursa
  • Head of fibula: not part of knee joint, risk of damaging neurovasculature in fx and dislocation
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8
Q

Ligaments of the knee

A
  • provide static stability
    • medial colateral ligament, lateral colateral ligament - prevent varus and valgus
    • anterior cruciate ligament, posterior cruciate ligament - prevent posterior and anterior slide
  • dynamic stability
    • quad/hamstring tendon
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9
Q

Menisci

A
  • cushions between bones
  • medial and lateral menisci
  • articular surfaces are covered with cartilage
  • medial meniscus is larger and less mobile, attached to MCL and posterior structures, injured more often
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10
Q

Knee Bursae

A
  • lubricate and cushion
  • front, lateral, medial
  • purpose:
    • decrease friction, shock absorber
  • > 10 bursae in the knee
  • Ones to know: prepatellar, deep infrapatellar, pes anserine
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11
Q

Muscles and Innervation

A
  • Femoral nerves innervate knee extensors
    • rectus femoris
    • vastus intermedius
    • vastus lateralis
    • vastus medialis
  • Sciatic nerve innervates knee flexors
    • tibial = semitendinosus, semimembranosus, biceps femoris (long head)
    • common peroneal = short head of biceps femoris
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12
Q

Movement at the knee

A
  • Flexion: bending heal towards buttock
  • Extension: straightening
  • External rotation: rotation away from the midline
  • Internal rotation: rotation toward the midline
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13
Q

Bursitis

A
  • bursae (sacs lined with synovial tissue) become inflammed
    • prepatellar, anserine, and infrapatellar are most common
    • usually insidious onset and cuased by repetitive motion
  • If acute onset, think about trauma and infection
    • rule out septic bursitis: usually secondary to trauma, less commonly associated with septic arthritis or bacteremia
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14
Q

Prepatellar Bursitis

A
  • located between skin and patella (superficial) - makes it more susceptible to infection
  • can see bursitis as well as septic bursitis
    • marked erythema, pain, warmth, swelling
    • common pathogen = staph aureus and strep
  • associated with trauma or chronic irritation from kneeling (housemaid’s knee)
  • often clinical diagnosis
    • xrays - generally not indicated
    • aspiration performed to r/o infection or for therapeutic purpose
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15
Q

Pes Anserine Bursitis

A
  • located below joint line (approx 6cm), medial flare of tibia
  • mainly bursitis
  • associated with overuse and early OA of medial compartment
  • often clinical diagnosis
    • local tenderness at area of bursa
    • negative varus maneuver
    • xrays generally not indicated, may see changes consistent with OA
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16
Q

Bursitis Treatment

A
  • if concerned with infection, aspiration with gram stain and culture
  • conservative treatment
    • compression, ice, short course of NSAIDs, activity modification, sometimes steroid injection
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17
Q

Baker’s Cyst (Popliteal cyst)

A
  • common in adults and children
  • Benign cyst:
    • swelling in popliteal fossa (inferior and medial)
  • Mechanism (2):
    • herniation of synovial membrane through joint capsule
    • egress of fluid through a normal communication to bursa
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18
Q

Baker’s Cyst - Children

A
  • common, M>F, medial>lateral
  • ddx: lipomas, xanthoma, vascular tumors, fibrosarcomas
  • use ultrasound if dx is in doubt
  • surgery rarely indicated; most resolve in 10-20 months
  • manage in collaboration with orthopedic surgery
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19
Q

Baker’s Cyst - Adults

A
  • frequently associated with meniscal tears and chrondral injury
    • giant cysts can be found in RA
  • common signs and symptoms:
    • posterior knee pain, knee stiffness, swelling or a mass behind the knee
  • enlarging cyst can mimic DVT
  • rupture of cyst can be quite painful
    • can resemble thrombophebitis as fluid flows into calf
  • conservative treatment first: treat underlying knee pathology, steroid injection, PT for compression/wrapping
  • Surgery: high incidence of recurrence
20
Q

Collateral Ligament Injuries

A
  • MCL injury more common than PCL
  • Can occur alone or in association with ACL, PCL, or meniscal tear
  • Many patients ambulate following injury
  • Common sxs: localized pain, swelling, stiffness, deformity
21
Q

MCL Injuries

A
  • MCL restrains valgus stress to knee
  • MOI: injury occurs as a result of a valgus stress to the knee
  • Physical Exam:
    • test with 30 degrees of flexion to negate ACL and PCL resistance - assess for laxity
  • Imaging:
    • xray may show calcification with chronic MCL sprains
    • MRI rarely needed but helpful if injury to ACL is suspected
22
Q

LCL Injuries

A
  • LCL resists varus stress
  • MOI: injury occurs as a result of varus force
  • Physical Exam:
    • test with 30 degrees of flexion to negate ACL and PCL resistance of varus stress
  • Imaging not usually necessary
  • Conservative treatment if mild
  • Complete disruptions (grade III) may need allograft reconstruction
23
Q

MCL & LCL Treatment

A
  • rest, ice, immobilize
  • non-operative care is mainstay for MCL and grade I and II LCL
    • consider PT referral
  • Refer:
    • severe injury with instability - combined ACL/MCL injuries will require MRI and possible repair
    • refractory cases
24
Q

ACL Injuries

A
  • MOI: hyperextension, marked internal rotation of tibia on femur
  • can be associated with meniscus tear and MCL tear
  • most commonly injured knee ligament
  • pop and immediate pain, unable to bear weight, marked swelling, instability
25
Q

ACL Injury Evaluation

A
  • hemarthrosis present in 70% of ACL injuries
  • Physical Exam:
    • lachman (most sensitive)
    • anterior drawer test
  • Imaging:
    • MRI gives definitive information as to the severity of the injury
26
Q

ACL Injury Treatment

A
  • Initial: rest, ice, immobilize, crutches
  • Refer to ortho
  • Partial tears generally treated conservatively
  • young, athletes and/or complete tears treated with surgery to replace ACL with autograft or allograft reconstruction
27
Q

PCL Injuries

A
  • trauma causes about 45% of PCL injuries
  • MOI:
    • hyperflexion of knee (most common for isolated PCL injury)
    • dashboard injury
    • fall on flexed knee with plantar flexion
    • hyperextension of knee, severe - ACL injury first
28
Q

PCL Injury Evaluation

A
  • MVA - look for soft tissue injuries and vascular injuries (popliteal artery)
  • Physical Exam:
    • initial: effusion and decreased ROM
    • posterior drawer test: most accurate & sensitive
    • posterior sag sign
  • Imaging:
    • MRI to confirm dx
29
Q

PCL Injury Treatment

A
  • PCL has capacity to heal
  • conservative treatment if isolated/chronic injuries, especially in older, less active patients
  • risk of non-op treatment = patellofemoral arthrosis
  • operative treatment in acute injuries, especially in young, active patients
30
Q

Meniscal Tears

A
  • Types:
    • bucket handle, horizontal, longitudinal, radial
  • Clinical Presentation:
    • trauma - twisting injury. onset of pain and swelling in 2-3 days, sxs = locking, popping, catching. pain along joint line
    • older adults present with degenerative tears with history of minor trauma or no trauma
31
Q

Bucket Handle Tear

A
  • More common medially
    • frequently associated with ACL tear
  • can “lock” the knee intermittently - full extension not possible
  • MRI - often missed, “double PCL sign”
  • Treatment:
    • closed reduction, arthroscopic resection
32
Q

Meniscus Tears PE, Imaging, Tx

A
  • Physical Exam:
    • tenderness on medial or lateral joint line
    • may have limited ROM
    • McMurray test - positive (painful click)
  • Imaging:
    • MRI is sensitive and specific
  • Treatment:
    • Initial - RICE
    • PT
    • referral to ortho for definitive tx if surgery likely
33
Q

Patella/Quadriceps Tendonitis

A
  • < 40 yrs = jumper’s knee
  • > 40 yrs = caused by lifting, increased physical activity, and weight gain
  • Clinical sxs
    • anterior knee pain - pinpoint
    • occurs after exercise or after sitting following exercise
    • associated with jumping or squatting
  • Physical Exam: tenderness at tendon attachment, normal ROM, pain with hyperflexion, severe cases - quadriceps atrophy
  • Treatment:
    • Rest, NSAID, immobilize/support
    • strengthening quads and hamstrings
    • slow return to activity
    • PT referral if pain after 3-4 weeks
34
Q

Patellar Dislocation/Subluxation

A
  • Dislocation: most often lateral, patella moves out of groove
  • Subluxation: excessive move laterally, not completely displaced
  • different from knee dislocation
  • frequent in adolescents
  • males = females
  • associated with osteochondral fractures
35
Q

Patellar Sublux Risk Factors

A
  • patella alta: abnormally high patella
  • laxity of ligaments
  • increased q-angle?
  • ITB tightness
36
Q

Patellar Dislocation Treatment

A
  • sedation
  • reduction
  • post reduction xray
  • immobilize
  • referral to PT
37
Q

Patellar Fracture

A
  • direct trauma
  • two view xray, some may require MRI or CT
  • non-operative care: closed fx, not displaced more than 3mm, not transverse, extension preserved
  • Operate if extensor mechanism compromised, displaced fx or transverse (avulsion) fx
  • OCD = osteochondroitin dissecans
    • loss of blood supply to bone under joint surface
    • adolescants/young adults
    • secondary to unrecognized trauma which disrupts or blocks tiny bone arteries
    • think about this if normal healing doesn’t occur
38
Q

High Fibula Fracture

A
  • proximal fx of fibula can be seen with trauma
  • check for distal neurologic deficits - peroneal nerve
  • can be seen in severe ankle external rotation injuries (Maisonneuve Fracture)
  • check joint above and below
39
Q

Tibial and Femoral Fractures

A
  • Distal Femur: supracondylar, condylar, combination
  • Proximal Tibia: plateau fractures
  • may be associated with collateral ligament injuries
  • young patients: high-energy trauma
  • older patients: underlying osteoporosis - low-energy trauma
  • Tibial plateau fx - valgus or varus force
  • Physical Exam:
    • check neurovascular integrity of lower leg and foot
    • assess other injuries as needed
  • Imaging:
    • X-ray: AP and lateral views
    • MRI to identify non-displaced fractures
  • Treatment:
    • non-surgical: non or minimally displaced fx
    • surgical: ORIF for displaced
    • open fx: emergent consult
40
Q

Knee Joint Infection - Septic Arthritis

A
  • acute onset of pain, erythema, warmth, swelling, reduced ROM
  • febrile
  • most common organisms: MRSA, MSSA, Gram neg. bacilli
41
Q

Knee Infections - special situations

A
  • diabetic pediatric - salmonella
  • arthoplasty - s pyogenes, Group A, B or G strep
  • tick bourne disease - lymes
  • sexually active - N gonorrhoeae
  • Rheumatoid - TB, fungal 2 TNF factor
  • endemic TB area - TB
42
Q

Knee Infections

A
  • important to get good hx - details like age, surgical hx, location help refine tx
  • Labs:
    • synovial fluid aspiration - gram stain & culture
    • blood cultures
    • CBC, CRP, ESR
  • start empiric therapy
    • IV abx for two weeks, PO abx for two weeks
  • risk of permanent joint damage
43
Q

Osteoarthritis of the knee

A
  • DJD of the knee
  • usually >40yo
  • greater risk of history of trauma
  • considered a wear and tear process - very common
  • can involve one, two or all three knee compartments
    • medial, lateral, patellofemoral
  • usually present with worsening pain, stiffness, muscle atrophy, decrease ROM over time
  • symptoms worse in the morning, improve with movement
  • as OA and DJD worsen, conservative tx will fail
44
Q

Osteoarthritis imaging

A
  • knee series:
    • standing bilateral AP, PA/lat/sunrise of affected side
  • evaluate for joint space narrowing, osteophytes, subchrondral sclerosis, subchondral cysts
45
Q

OA Treatment

A
  • Conservative:
    • NSAIDS, APAP for pain
    • Injections: steroids, viscosupplementation
  • bracing
  • exercise and weight loss
  • surgery: TKA
46
Q

Approach to Patient with Knee Pain

A
  • Clinical algorithm
  • Imaging guidelines: ottowa rules
47
Q

Ottowa Rules for Xray of the Knee

A
  1. age >/= 55yrs
  2. isolated tenderness of patella (with no other bony tenderness of the knee)
  3. tenderness at the head of the fibula
  4. inability to flex the knee to 90 degrees
  5. inability to bear weight both immediately and in the ED for four steps, regardless of limp

Must have one or more.

Orthopaedics & Rheumatology (5 decks)

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