Lecture #7 (Knee, Hip & Pelvis) Flashcards
True or false:
The knee joint is made up of three articulations.
True: between the medial and lateral condyles and tibial plateau and between the patella and femur
What is the correct classification of the knee joint?
Double condyloid
What is the open packed position of the knee joint? Closed packed?
Open= 25 degrees flexion Closed= full extension
How far can the tibia rotate? Is this in weight bearing or NWB?
NWB about 50 degrees
How does tibial rotation occur during weight bearing?
The femur rotates medially on the tibia…this is that screw home mechanism
What are the circular rims of fibrocartilage found in the knee that are good for compression stresses, not shear forces?
Mensci (the lateral is an incomplete circle and the medial is a “C” shape)
What are the functions of the mensci (x5)?
Protection, stability, lubrication, force transmission, and aiding in roll of femoral condyles
Which meniscus is more often injured, why?
Medial because is moves less than the lateral meniscus but mainly because it takes most of the sliding and gliding of the joint (medial condyle is bigger)
How much does the medial meniscus move? The lateral? In what direction do they move?
Medial= 6mm
Lateral= 12mm
They move in an A/P direction
What is the unholy triad?
The ACL, MCL, and medial meniscus,,,there is also some attachment of the medial meniscus to the semimembranosis
What is the lateral meniscus attached to?
The PCL and coronary ligaments (not to the LCL)
Where does a meniscal cyst occur?
Lateral meniscus
Where is the vascularization of the menisci located?
In the outer 1/3…this is why the menisci do not really heal well because they have very little blood supply
Where does a meniscus tend to be stiffer and where does it tend to be weaker?
Stiffer= circumferentially Weaker= radially
What does the MCL and LCL do?
Prevent rotation of the tibia on the femur when the knee is extended (they are taunt then) and protect from varus and valgus forces
What structure helps support the medial knee in addition to the MCL? What about the lateral knee in addition to the LCL?
Medial knee= MCL and pes anserine
Lateral knee= LCL and IT band
What ligament prevents posterior displacement of the tibia on the femur? What else does this ligament do?
PCL–it also helps prevent hyperextension of the knee
What ligament prevents anterior translation of the tibia and serves as a secondary support to varus and valgus forces on the knee? What else does it prevent?
ACL–it also helps prevent excessive rotation of the tibia on a fixed femur
How many bands of the ACL are there? What are they?
3–anteromedial
intermediate
posterolateral
During what motion do the cruciate ligaments become taunt and rub against one another? During what motion do they become lax?
Taunt= medial tibial rotation & femoral lateral rotation Lax= lateral tibial rotation & femoral medial rotation
Where does the peak stress on the ACL occur? Why?
Between 28 and 14 degrees of extension…because the angle of pull from the quads changes
How much stress is placed on the ACL during OKC exercises?
60% (but it increases more as you extend the knee)
What is the normal amount of valgus that people tend to have?
5-10 degrees
What measurements constitute genu varus and genu valgum?
Genu varum= 180 degrees and over (bowlegged)
Genu valgum= 165 degrees or less (knock-kneed)
A varus knee compresses which compartment of the knee? A valgus knee?
Varus= medial compartment Valgus= lateral compartment
What the Q-angle for men? Women? Genu varum? Genu valgum?
Men= 10-15 degrees
Women= 15-20 degrees
Genu varum= less than 10 degrees
Genu valgum= more than 15 or 20 degrees
What is the screw home mechanism?
Medial rotation of the femur (or external rotation of the tibia) during close chain movement. This is what allows us to stand up (full extension of knee) without activating any muscles
What does the PCL and menisci do during the screw home mechanism?
Stop the anterior rolling of the femur & help start a posterior glide of femur
What creates the “locked” knee at the end of the screw home mechanism?
Rotation at the knee and the extension at the hip
What unlocks the knee during closed chain?
Action of the popliteus and hip flexion
True or false:
The last 10 to 15 degrees of knee extension is completed by the patella.
False…it is accomplished by the quadricep muscles because the patella loses it’s line of pull. Twice the quad strength is needed at this point.
When does the patella begin to engage in knee extension?
At 15-20 degrees of flexion
Where is there common articular cartilage breakdown of the patella? Why?
On the medial (odd) facet because this area engages in knee extension later than the others so it is not as used to “force” as the other facets
How far should the patella glide total?
5-7 cm
In what position is the patella compressive forces the greatest?
In 60-90 degrees if flexion. This is important because this is when patients will complain about pain (i.e. walking up the stairs, deep squating, defensive stance, etc.)
On what side is it more common to have poor patella tracking? Is patella tracking issues more common in women or men?
On the lateral side
More common in women
How long is the femoral neck? What is it’s function? How does having a longer or shorter femoral neck affect strength?
About 5cm…the femoral neck helps to create a moment arm for torque production. Because it does this, the longer the neck (meaning the longer the moment arm), the more strength that is able to be produced.
What is the angle of Wiberg (center edge angle)? What should this angle be?
The amount of the inferior tilt of the acetabulum…about 35-38 degrees
What does a smaller angle of Wiberg promote? What about a greater angle?
Smaller angle= promotes hip dislocation
Greater angle= less motion (more stability)
During closed chain exercise, what moves on what between the femur and the pelvis? What about open chain exercise?
Closed chain= pelvis moving on femur
Open chain= femur moving on pelvis
What is the function of the labrum (the “horseshoe” shaped fibrocartilage in acetabulum)?
Add concavity/stability to the hip joint (improve synovial layer), deepen the socket, and help with force dispersion at the hip
What is the transverse acetabular ligament?
The ligament that spans the gap of the acteabulum inferiorly–it forms the roof under which the vessels pass under as they head into the hip
What are the three ligaments of the hip?
Iliofemoral (Y) ligament
Pubofemoral ligament
Ischiofemoral ligament
What does the Y ligament do? Where is it located?
Restrict extension, external and internal rotation, and abduction and adduction…located anteriorly
What does the pubofemoral ligament do? Where is it located?
Restricts extension, abduction, and external rotation…located medial
What does the ischiofemoral ligament do? Where is it located?
Restricts extension, internal rotation, and adduction….located posteriorly
What is the open packed position of the hip?
30 degrees abduction and 30 degrees flexion
What creates a stable hip joint?
When all the ligaments are coiled or twisted in neutral
What hip motion causes an increase in the twisting of the hip joint ligaments but a lessening of the joint articulation?
Hip Extension
What hip motions (x3) causes a looser twisting of the hip joint ligaments but increases the joint articulation making the hip joint more stable?
Hip flexion, abduction, and external rotation
What hip joint motions (x2) causes a looser twisting of the hip ligaments and lessens the joint articulation? What is bad about this motion?
Hip flexion and adduction…this is a common MOI for hip dislocation.
What is the angle of inclination? What is normal?
The angle of the femoral neck and the femoral shaft.
-125 degrees is normal
What two things does the angle of inclination do?
Allows the femur to angle medially downward from the hip during the support phase of walking/running. It also produces single leg support beneath the body’s center of gravity.
What is considered coxa vara? Coxa valga?
Coxa vara= smaller angle of inclination (less than 125)
Coxa valga= larger angle of inclination (more than 125)
Why is coxa valga more unstable than coxa vara?
Because there is a greater angle of inclination in someone with coxa valga, their hip is less stable because the femoral head is almost out of the acetabulum (whereas coxa vara has the femoral head even more in the acetabulum)
What are the clinical implications of coxa valga?
Longer leg
Less stability
Weaker hip (less moment arm/line of pull for the glute med)
What are the clinical implications of coxa vara?
Shorter leg
More stability
Stronger hip (greater moment arm/line of pull for glute med)
Increase bending force on the femoral neck (increase in possibility of femoral neck fx)
What is the angle of torsion?
The angle between the head/neck of the femur and the shaft of the femur (looking above). It kinda measures where the femur is in the acetabulum…i guess
What is the average angle of torsion in adults?
15 degrees
What does an increase in angle of torsion mean?
Excessive anteversion (the head and neck of the femur are rotated more anteriorly in the acetabulum creating a greater internal torsion of the femoral shaft)
What does a decrease in the angle of torsion indicate?
Retroversion (the head and neck of the femur are rotated more posteriorly in the acetabulum producing a greater external rotation of the femoral shaft)
What angle of torsion indicates excessive anteversion? What are two possible clinical signs?
Greater than 15 degrees
Pigeon toed or squinting patella
What angle of torsion indicated retroversion? What are two possible clinical signs?
Less than 15 degrees
Duck footed or frog-eyed patella
What happens to the back during an anterior pelvic tilt? What hip motion would be affected?
Increased lordosis
Hip flexion
What happens to the back during an posterior pelvic tilt?
What hip motion would be affected?
Decreased lordosis
Hip extension
What spinal motion would be affected during a lateral pelvic tilt? What hip motion would be affected?
Lateral side bend
Hip ab/adduction
What spinal motion would be affected during a pelvic rotation? What hip motion would be affected?
Lumbar rotation
Hip external rotation, extension, abduction with opposite internal rotation, flexion, adduction (pretty much everything)
What is the main functions of the SI joint?
Stress relief within the pelvic ring and the transfer of forces between the axial skeleton and the lower extremity
What type of joint is the Si joint?
Atypical diarthrosis
True or false:
When the SI joint slips out of place, it typically does not slip back into place.
True…this is because of just how irregular the joint is
What is the function of the sacrum?
It disperses the weight of the upper body around the pelvis
What occurs during nutation of the sacrum?
A superior sacral anterior tilt (the inominate bones don’t move)
How much active sacral nutation is average? How much passive?
Active= 2-3 degrees Passive= 7-8 degrees
What is translation of the sacrum? What plane does this motion occur in?
Sliding up or down or rotating (like window wipers)…frontal plane motion
True or false:
There is normally slight anterior and posterior motion of the innominate bones on the sacrum during normal gait.
True..this is for stress relief off the structures
What are four examples of abnormal unilateral ilial motion?
Upslip
Torsions/Rotations
Flaring
Excessive nutation (sacral torsion)
