CM Knee Flashcards
(67 cards)
1
Q
Bones of the knee
A
Femru
Tibia
Fibula
Patella
2
Q
Knee Joints
A
Largest joint in the body Primarily function as a hinge VERY complex 1. The knee joint proper=Tibiofemoral joint 2. Patellofemoral joint
3
Q
Knee ligaments
A
MCL, LCL, ACL, PCL
4
Q
The knee ligaments provide what kind of stability
A
Static
5
Q
The Quad/Hamstrings provide what kind of stability
A
Dynamic
6
Q
These are the cushions between the bones of the knee (sit on top of the tibia)
A
Menisci (Medial and Lateral)
7
Q
The articular surfaces of the knee are covered with
A
Cartilage
8
Q
The strongest and largest bone in the body
A
Femur
9
Q
Femur
A
Holds ~2L of blood
Enlarged femoral condyles-articulate on enlarged tibial condyles (distal femur, prox tibia)
10
Q
Tibia
A
Medial
Medial and lateral condyles (AKA tibial plateaus) serve as receptacles for femoral condyles
Tibial tuberosity (attachment for the patellar ligament/tendon
Tibia bears most of the weight
11
Q
Fibula
A
Lateral NOT part of the knee joint Doesn't articulate w/femur or patella Biceps femoris and LCL attachments Used a lot for bone grafting
12
Q
Patella
A
Triangular shaped bone Sesamoid bone (In quadraceps femoris) Articulates w/femur Embedded in Quad and Patelllar tendons Acts as a pulley, improving angle of pull (q angle) Can cause/be a part of OA
13
Q
Bony Landmarks of the Knee
A
Superior and Inferior patellar poles Tibial tuberosity Gerdy's tubercle Medial and lateral femoral condyles Prox anterior medial tibial surface Head of fibula
14
Q
Bursae
A
Synovial Cavity: supplies knee w/synovial fluid; lies under patella between surfaces of tibia and femur; “Capsule of the knee”; synovial fluid can leak out w/an open fx and disruption of the capsule
15
Q
Infrapatellar Fat Pad
A
Just post to patellar tendon
Insertion point for folds of tissue called plica
Plica tear/injury can cause knee to lock up
16
Q
Knee Bursae
A
Front: Suprapatellar, prepatellar, deep infrapatellar, pretibial (should flow between front and back of knee)
Lateral: Gastrocnemius, fibular, fibulopopliteal, subpopliteal
Medial: Medial gastroc, anserine bursa, semimembranosa
17
Q
Knee Bursae Functions
A
Shock absorbers
Decrease friction
>10 bursae in the knee
Overdeveloped or enlarged bursa indicates knee injury in that location
18
Q
Knee Muscle Functions
A
Flexors
Extensors
ADductors
ABductors
19
Q
What nerves innervates the knee extensors
A
Femoral Nerve
20
Q
Knee extensor muscles
A
Rectus femoris
Vastus intermedius
Vastus lateralis
Vastus medialis
21
Q
What nerve innervates the knee flexors
A
Sciatic Nerve: Tibial nerve and Common peroneal nerve
22
Q
Tibial nerve innervates:
A
Semitendinosus, semimembranosus, biceps femoris (long head)
23
Q
Common Peroneal nerve innervates:
A
Biceps femoris (short head)
24
Q
Blood supply to the knee extensors
A
LCFA: Lateral circumflex femoral artery (ascending, transverse, descending)
Supplies the femoral head
25
Blood supply to the knee joint
Medial genicular arteries penetrate the joint
26
The "BIG" artery in the knee
"The Big Red One"
| Popliteal artery: many different blood supply routes to knee, little risk of avascular necrosis
27
Being in a plane parallel to the sagittal suture
Sagittal plane
28
Divides the body into dorsal and ventral (back and front)
Coronal or Frontal plane
29
Divides the body into cranial and caudal (head and tail)
Transverse or Axial plane
30
Bending heel towards buttucks to 0 degrees of flexion
Flexion
31
Straightening to about 140 degrees
Extension
32
Rotation away from midline
External rotation (knee must be flexed >20-30 degrees for this to be possible)
33
Rotation towards midline
Internal rotation (knee must be flexed >20-30 degrees for this to be possible)
34
MCL Injuries
MCL resists valgus stress to knee
Injury occurs as a result of valgus stress to the knee (medial force)
Place knee off table and load to find instability
Xrays may with chronic MCL sprains show calcifications (from repeat injuries)
MRI is rarely needed but helpful if injury to ACL is suspected w/MCL
US can show if ligament is torn or not
35
LCL Injuries
LCL resists varus stress
Injury occurs as a result of varus forces
Test w/30 degrees of flexion to negate ACL and PCL resistance of varus stress
Conservative tx if mild (rest, ice, brace)
Complete disruptions may need allograft reconstruction
36
MCL and LCL Tx
Rest, ice, immobilize if mild case
Non-operative care is the mainstay
Scar heals in 6wks-1yr (ligaments don't heal but form scar tissue, 60-80% tensile strength of ligament)
Combined ACL/MCL injuries will require MRI and possible repair---refer to ortho
37
ACL Injuries
Occur most often in football and basketball injuries in young pts, downhill ski accidents in older pts
Occur as a result of shearing forces on the ACL while the quad muscles are contracting especially when the knee is at 0-30 degrees
Main forces that cause this injury:
1. Hyperextension
2. Marked internal rotation of tibia on femur
38
Cruciate
Cross
39
ACL Injury Evaluation
Hemarthrosis present in 70% of ACL injuries
Lachman & Anterial Drawer Tests: attempt, but write "unable to perform Lachman and AD tests due to swelling and pain"
MRI gives definite info as to the severity of the injury
40
ACL Tx
Depends on the pt and severity of injury
Partial tears generally tx conservatively: rest initially, bracing, PT for quad and hamstring strengthening
Complete tears commonly tx w/surgery to replace the ACL with either autograft (middle 1/3 patellar tendon) or allograft reconstruction
41
Types of Meniscal Tears
Bucket Handle
Horizontal
Longitudinal
Radial
42
A Bucket Handle Meniscal tear is frequently associated with what kind of tear?
ACL tear
43
Bucket Handle meniscal tear
- More common medially
- Condyles catch the tear, very painful
- Can lock the knee (can't fully extend) -torn piece gets caught under the condyle and impedes motion; important to note if it clicks AND hurts
- Presentation: intermitently lock, cannot get full extension, can come and go
- Often missed on MRI
- Double PCL sign (lies just post to PCL)
- Tx: closed reduction (temporarily reduces tear), arthroscopic resection, not much success w/repair
44
Double PCL sign
Bucket Handle Meniscal tear
45
What should you not do to a Baker's Cyst
Aspirate! Popliteal artery is in that area
46
Herniation of synovial membrane thru joint capsule (exclusive to knee)
Baker's Cyst
47
Baker's Cyst
- Normal fluid flow thru a normal communication of a bursa
- Mimics DVT when they ruputre
- Tx: Conservative tx first (knee joint steroid injection, PT for compression/wrapping, US); Surgery-high incidence of recurrance
48
Baker's Cyst in Children
- Common in kids
- M>F
- Medial>Lateral
- DDx: lipomas, xanthomas, vascular tumors, fibrosarcomas
- Use US if Dx is in doubt
- Surgery is RARELY indicated; most resolve in 10-20 months
49
Baker's Cyst in Adults
- Freq assoc w/meniscal tears and chondral injury (one way valve of fluid flow)
- If pt doensn't have pain, no need to tx
- Giant cysts can be found in RA
- Rupture of cyst can be quite painful
- Can view on US
- Rupture can resemble DVT as fluid flows into calf
50
Bursitis
- Inflammed synovial fluid: prepatellar, infrapatellar, pes anserine
- Usually insidious onset and caused by repetitive motion occupations, gets worse over time
- If acute onset, think about trauma and infection (rarely, drug allergy)
- Make sure it's not septic bursitis: Usually secondary to trauma or cellulitis (50-70%); less commonly contiguous septic arthritis or bacteremia (10%); Hot, tender to the touch
51
Bursitis Tx:
- If concerned for infection, consider I&D and cultures
- CBC, ESR, Chemistries
- Conservative Tx (not for septic bursitis): compression, ice therapy, activity modification, sometimes steroid injection
52
Patellar Fx
- Direct trauma (ex dashboard injury)
- Get 2 view xray
- Some may require CT or MRI but usually unnecessary
- Non operative care if not open, not displaced more than 3mm, not transverse, extension preserved
53
Patellar Fx Tx
- Operate if extensor mechanism compromised
- Displaced fx or transverse (avulsion) fx
- OCD: osteochondroitin dissecans - loss of blood supply to bone under joint surface; usually adolescents/young adults; usually secondary to unrecognized trauma which disrupts or blocks tiny bone arteries; think about this if normal healing doesn't occur
54
Patellar Dislocation/Subluxation
**Different from "knee dislocation"
-Freq in adolescents
-Males=Females
+/- Assoc w/osteochondral fxs
55
Patellar Dislocation Risk Factors
- Patella alta: abnormally high patella
- Laxity of ligaments: esp in kids
- Increased q angle: more stress on patella and quad/patella tendons (Measure q angle by measuring from ASIS to middle of patella to tibial tuberosity)
- Femoral anteversion or genu valgum
56
Patellar Dislocation Tx
- Sedation + Combo of Lido and Marcaine
- Reduction
- Post reduction films
- Immobilize
- CT and MRI follow up if OCD or bone bruise causing gait disturbance
57
High Fibula Fx
- Prox fx of fibula can be seen w/trauma
- Check for distal neurologic deficits
- Can be seen in severe ankle external rotation injuries (press on fibular head w/ankle injuries)
- Maisonneuve Fx ??
- REMEMBER: Check joint above and below w/any injury
58
OA of the Knee
- DJD of the knee
- Usually >40yo, VERY common
- Greater risk w/hx of previous trauma
- Considered a wear and tear process
- Can involve one, two or all three knee compartments (medial, lateral, patellofemoral)
59
Sxs of Knee OA
- Usually present w/worsening pain, stiffness, muscle atrophy, decreased ROM over time
- Sxs worse upon arising, but will often improve w/movement and activity
- As OA and DJD worsen, conservative tx measures will begin to fail
60
Knee Films
```
Standing bilateral (shows pressure on knees)
AP
PA
Lat
Sunrise
```
61
Evaluate Xrays for
Joint space narrowing
Osteophytes (icicles on knee)
Subchondral sclerosis
subchondral cysts
62
Knee OA Tx
- Conservative when able (NSAIDs/APAP for pain, Steroid injections q3-6mo; vicosupplementation)
- Bracing
- Exercise and weight loss
- Surgery
63
What are the most common organisms of knee joint infections
MRSA
MSSA
Gram Negative Bacilli
(These are causing more amputations)
64
Knee joint infections
- Important to get a good hx
- Details like age, surgical hx, location help refine tx
- Empiric therapy after collection of blood and joint for culture
65
Knee joint infections: Special situations
- Diabetic pediatric: Salmonella
- Arthroplasty: S pyogenes, Group A B or G strep
- Tick bourne disease: Lymes
* *Sexually active: N. gonorrhoeae
- RA: TB, Fungal 2 TNF inhibitor
- Endemic TB area: TB
66
Knee joint infection Tx
- Abx: often for weeks to months
- Cultures: repeat to check for clearance
- Biopsy bone: certain situations
67
Steroid injections
Study conclusion: Steroids are useful adjuncts in the management of pts w/arthritic joints; this study shows no increased incidence of infection in pts given steroid injections prior to arthroplasty
