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
2
Q
Femur
A
- Strongest and largest bone in the body
- Enlarged femoral condyles articulate with the tibial plateau
- Articulates: tibial plateau, posterior patella
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
- age >/= 55yrs
- isolated tenderness of patella (with no other bony tenderness of the knee)
- tenderness at the head of the fibula
- inability to flex the knee to 90 degrees
- inability to bear weight both immediately and in the ED for four steps, regardless of limp
Must have one or more.
