Other Flashcards
What is the orientation of the elbow joint
10-15 degrees valgus
What is a primary and secondary constraint
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
Primary and secondary constraints of the elbow
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
Key points about interosses membrane
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
Passive structure support proximal and distal radioulnar
Interosseos membrane, triangular fibrocartilage complex (TFCC), annular ligament, oblique cord (limits supination)
Movements during full arm elevation
Scapular - external rotation, post tilt and upward rotation
Clavicle - Post rotation, elevation, retraction
Humerus - abducts
Sternoclavicular joint stability
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.
Acromialclavicular joint stability
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
What is function of the conoid ligament
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
GHJ stability
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
Ligaments of GHJ
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.
Positive and negative ulna variance
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
Extrinsic ligaments of the wrist
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
Intrinsic ligaments of the wrist
Palmar and dorsal mid carpal, inerosseus between adjacent carpal bones
Bony stability at the elbow
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.
Alignment of hip joint components
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
Alignment of the femur in frontal plane
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.
Alignment of femur in transverse plane
Refered to as femoral anteversion, angle between neck of femur and the condyles. Normal is 15, <15 is retroversion and >15 is excessive eversion
Two ways in which frontal plane alignment of the knee joint are measured
Mechanical and anatomical
Mechinical alignment of the knee joint
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.
Anatomical alignment of the knee joint
Simply a line through the center of each of the bones. Normal is a 5 degree valgus.
3 knee joints
Tibiofemoral and patello femoral are enclosed by knee joint capsule while superior tibiofibular is not.
Knee joint capsule
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)
Tibiofemoral locking and shape of condyles
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.
Tibiofemoral menisci
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.
Main ligametns of the knee
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
Patelloformal joint functions
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)
What is the Q angle
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)
Stability at the patello femoral joint
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
Force transmission through the patella
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)
Carpal deformities
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.
