Other

Question 1

What is the orientation of the elbow joint

Answer 1

10-15 degrees valgus

Question 2

What is a primary and secondary constraint

Answer 2

Primary is something which when cut/removed will cause laxity. A secondary is something that when cut is inefficient enough to causes laxity but if released after the primary it will increase laxity

Question 3

Primary and secondary constraints of the elbow

Answer 3

Primary - Humeroulnar articulation, anterior band of medial collateral ligament, lateral collateral ligament complex (has annular ligament)
Secondary - Joint capsule, radiohumeral articulation, common flex/pro tendon and common ext tendon

Question 4

Key points about interosses membrane

Answer 4

As pressure on interosseus membrane increases so to does force transmission at proximal and distal radio ulnar joints. It is most laxed in full pronation therefore fractures of radius most often occur due to limited force transmission. Starts below radial tuberosity and fibers run inferior and medially

Question 5

Passive structure support proximal and distal radioulnar

Answer 5

Interosseos membrane, triangular fibrocartilage complex (TFCC), annular ligament, oblique cord (limits supination)

Question 6

Movements during full arm elevation

Answer 6

Scapular - external rotation, post tilt and upward rotation
Clavicle - Post rotation, elevation, retraction
Humerus - abducts

Question 7

Sternoclavicular joint stability

Answer 7

Bixaxial saddle joint that can perform protraction/retraction and elevation/depression. Due to the disparities between the clavical and clavicular notch on the sternum, most of the stability comes from ligaments. Have the anterior (retraction) and posterior (protraction) sternoclavicular ligaments. Interclavicular ligaments connects the superior surfaces of the two clavicals via the jugular notch of sternum and the costoclavicular ligament connects inferior clavical to first costal cartilage.

Question 8

Acromialclavicular joint stability

Answer 8

Pland/gliding joint that has extra collegen fibers in superior and inferior aspects of capsule which differe s from SCJ which has extra in ant/post. Trapezoid ligament resists medial glide of scap relative to clavicle . Conoid resists superior glide of lateral clavical

Question 9

What is function of the conoid ligament

Answer 9

It links the movements at the scpular and clavicle, conoid tubercle to coronoid process. During abduction there is upward rotation of scap meaning the corocoid process is moving away from conoid causing tightness. This pulls the conoid tubercle inferior causing posterio rotation of clavicle

Question 10

GHJ stability

Answer 10

Synovial ball and socket joint. Shallow glenoid cavity (smaller than humeral head) and not much bony stability so needs to get stability from other areas such as the labrum (fibrocartilage ring attached to glenoid fossa which increase depth and articulation SA) ligaments and muscles

Question 11

Ligaments of GHJ

Answer 11

Coracohumeral and superior glenohumeral both are taut in anatomical position and prevent the head of humerus moving inferior.
Middle glenohumeral is absent in some and does not do much. Inferior glenohumeral ligament complex has anterior band, post band and axillary pouch (allows for full abduction ROM). Also has transvers humeral ligament for long head of biceps tendon to labrum.

Question 12

Positive and negative ulna variance

Answer 12

When the ulna is shorter than normal this means negative ular varience and causes more load through lunate and capitate. When ulna is longer than positive meaning more load through TFCC

Question 13

Extrinsic ligaments of the wrist

Answer 13

radial colateral (radial styloid to scaphoid), ulnar collateral (ulna styloid to triquetrum).

Palmar radiocarpal and ulnocarpal both resist extensive wrist extension. Dorsal radiocapal resists extensive wrist flexion

Question 14

Intrinsic ligaments of the wrist

Answer 14

Palmar and dorsal mid carpal, inerosseus between adjacent carpal bones

Question 15

Bony stability at the elbow

Answer 15

In the first 20 degrees of flexion the olecranon process of ulnar articulates with olecranon fossa of humerus. Coronoid process of ulnar prevents against posterior dislocation during flexion.

Question 16

Alignment of hip joint components

Answer 16

Acetabulum - Anterior, lateral and inferior

Head of femur - anterior, superior, medial

In standing there is more exposed anterior surface (meaning F>E ROM)

Both flexion and abduction move the femoral head deaper into the acetabulum

Question 17

Alignment of the femur in frontal plane

Answer 17

Angle formed between neck and shaft of the femur, Normal is 125.

• Coxa vara is <125 (distal is medial) causes increased moment arm for glute med due to insertion on greater trochanter
• Coxa valga is >125, causes the direction of the head of the femur to be much more superiortherefore moving direction of weight from femur.

Question 18

Alignment of femur in transverse plane

Answer 18

Refered to as femoral anteversion, angle between neck of femur and the condyles. Normal is 15, <15 is retroversion and >15 is excessive eversion

Question 19

Two ways in which frontal plane alignment of the knee joint are measured

Answer 19

Mechanical and anatomical

Question 20

Mechinical alignment of the knee joint

Answer 20

Line from femoral head to intercondylar notch (femoral mechanical axis). Line from center of proximal tibia to center of ankle joint (tibial mechanical axis). These two lines form the HKA angle which on average is just below 180 degeers causing a 1 degeer valgus at the knee joint.

HKA angle indicates the load distributions between medial and lateral compartments of the knee.

Question 22

Anatomical alignment of the knee joint

Answer 22

Simply a line through the center of each of the bones. Normal is a 5 degree valgus.

Question 23

3 knee joints

Answer 23

Tibiofemoral and patello femoral are enclosed by knee joint capsule while superior tibiofibular is not.

Question 24

Knee joint capsule

Answer 24

Connects to the lateral and medial margins of the patella. Continuous with the medial colateral ligament. Posteriorly it is reinforced by the oblique poplitea ligament (main resistor to hyperextension)

Question 25

Tibiofemoral locking and shape of condyles

Answer 25

During standing the knee is locked into extension via medial rotation to reduce muscle work. The popliteus muscle unlocks the knee via lateral rotation of the femur on tibia.

Shape of femoral condyes contribute to stabiltiy. In flexion the condyles are much more curved while in extension surfaces are much more broad and flat.

Question 26

Tibiofemoral menisci

Answer 26

Main function is to increases the ocntact area between the tibia and femur. Lateral is much more mobile while the medial is much larger and surves as casular attachment point.

Question 27

Main ligametns of the knee

Answer 27

Tibial collateral resists valgus. Fibular collateral resists varus. ACL resists anterior translations of tibia on femur as well as valgus and int rot. PCL resists posterior translation of tibia on femur and ext rot. Anterior lateral ligametn (ALL) resists tibial internal rotaion

Question 28

Patelloformal joint functions

Answer 28

Patella fucntions to increase the moment arm of the quadriceps. Contact area of patella moves proximal and increase is knee flexes therefore menaing that the most contact is achieved through full knee flexion (end range of quads)

Question 29

What is the Q angle

Answer 29

represents the lateral pull of the quads. 1 line through tibia tuberosity up to center of patella and another from ASIS to center of patella. Normal is between 12-20 (men on lower end and women at greater end)

Question 30

Stability at the patello femoral joint

Answer 30

Achieved in 3 main ways:

• Disslocation often happens lateraly due to lateral pull of quads but lateral femoral condyle extends out further to help prevent this
• VOM, segment of VM that inserts on medial aspect of patella
• Medial patellofemoral ligament

Question 31

Force transmission through the patella

Answer 31

Patelo femoral joint reaction force = PFJRF, this increases with knee flexion, during knee extension there are more shear forces as oppsoed to compression forces seen in flexion.

Joint stress is force/contact area

PFJ reaction force determined by angle of knee flexion (more = increased) and quad force of contraction.

PFJ joint stress is determined by PFJRF and the degree of knee flexipon (more is less stress due to larger contact area)

Question 32

Carpal deformities

Answer 32

Whe there is laxity of the joint capsule and ligaments of the wrist load bearing is greatly effected. As there is limited bony stability at this joint the carapl bones will just fall onto the distal radius. This means that lunate needs to transfere more load, the TFCC has greater compression and there is more force transmission through the ulna.