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