Joints

Question 1

Shoulder Joint (Glenohumeral Joint)

Answer 1

• A ball and socket joint between the scapula and humerus.
• It is one of the most mobile joints in the body.
• Formed by the articulation of the head of the humerus with the gelnoid cavity of the scapula.
• Since it is a synovial joint, the articulating surfaces are covered with hyaline cartilage
• The head of the humerus is much larger than the glenoid fossa - this gives the joint a wide range of movement at the cost of instability. In order to reduce the disproportion in surfaces, the glenoid fossa is deepend by a fibrocartilage rim, called the glenoid labrium.
• Joint capsule - a fibrous sheath encloses the structure of the joint. Extends from the anatomical neck of the humerus to the border of the glenoid fossa. The joint capsule is lax allowing for greater mobility.
• Synovial membrane - lines inner surface of joint capsule and produces synovial fluid to reduce friction. There are also several synovial bursa present, which further reduces friction.

Question 2

Bursa

Answer 2

• Synovial flui filled sac that acts as a cushion between tendons and other joint structures.

Question 3

Important bursa of the shoulder

Answer 3

• Subacrominal - located deep to deltoid and acromion, and superficial to supraspinatus tendon and joint capsule. It reduces friction beneath deltoid promoting free motion of the rotator cuff tendon.
• Subscapular - located between subscapularis tendon and scapula. Reduces wear and tear on the tendon during movement at the shoulder joint.
• Subcoracoid bursa

Question 4

Ligaments in the shoulder

Answer 4

• Ligaments in the shoulder play a key role in stabilizing the bony structures.
• Glenohumoral ligaments (superior, middle, and inferior) - joint capsule is formed by this group of ligaments connecting the humerus to the glenoid fossa. Main source of stability in the shoulder, prevents it from dislocating anteriorly.
• Coracohumeral ligament - Attaches the base of the coracoid process to the greater tubercle of the humerus. Supports superior part of the joint capsule.
• Transverse humeral ligament - Spans distance between 2 tubercles of the humerus. it holds the tendon of the long head of biceps in intertubercular groove.
• Coraco-clavicular ligament - Made of trapezoid and conoid ligament. Runs from clavicle to caracoid process of the scapula. Works with acrominoclavicular ligament to maintain alignment of clavicle with scapula.
• Coracoacromial ligament - Runs between acromion and coracoid process of the scapula from coraco-acrominal arch. It overlies the shoulder joint, preventing superior displacement of humeral head.

Question 5

Movements of the shoulder and the muscles involved

Answer 5

• Extension - posterior deltoid, latissimus dorsi, and teras major
• Flexion - Pectoralis major, anterior deltoid, coracobrachialis, biceps brachii weakly
• Abduction
  
  • First 0-15⁰ - supraspinatus
  • Next 15-90⁰ - middle fibres of deltoid
  • Past 90⁰ - Scapula needs to be rotated to achieve abduction - carried out by trapezius and serratus anterior
• Adduction - pectoralis major, latissimus dorsi and teres major,
• Internal Rotation - Subscapularis, pectoralis major, latissimus dorsi, teres major, and anterior deltoid
• External Rotation - Infraspinatus and teres minor

Question 6

Shoulder Stabilizers

Answer 6

• The shoulder joint is very mobile at the expense of stability. However, there are some parts the contribute to stability.
• Rotator cuff muscles - dynamic stabilizers. Muscles surround the shoulder joint, attaching to tuberosities of the humerus, while also fusing with the joint capsule. These muscles at rest act to compress humeral head into glenoid cavity.
• Glenoid labrum - a fribrocartilaginous ridge surrouding the glenoid cavity. It deepens the cavity and creates a seal with head of the humerus. Reduces risk of dislocation.
• Ligaments - act to reinforce the joint capsule
• Biceps tendon - acts as minor humeral head depressor

Question 7

Neurovascular Innervation of the Shoulder

Answer 7

• Shoulder joint is supplied by the anterior and posterior circumflex humeral arteries (branch of axillary artery). The suprascapular artery (branch of thyrocervical trunk) also contribute.
• Innervation - axillary, suprascapular, and lateral pectoral nerves.

Question 8

Muscles of the shoulder

Answer 8

• Extrinsic - originate from torso and attach to the bones of the shoulder.
• Intrinscic - originate from scapule and/or clavicle and attach to the humerus.

Question 9

Intrinsic Muscles of the Shoulder

Answer 9

• Deltoid: Shaped liked a triangle. Can be divided into anterior, middle, and posterior part. It originates from scapula and clavicle, and attaches to deltoid tuberosity on lateral surface of the humerus. Innervated by the axillary nerve.
• Teres Major: Formes inferior border of quadrangular space (gap that axillary nerve and posterior circumflex humeral artery pass through). It originates from posterior surface or the inferior angle of the scapula. It attaches to medial lip of intertubercular groove of the humerus. Innervated by the subscapular nerve.
• Rotator cuff muscles

Question 10

Rotator Cuff Muscles

Answer 10

• Group of 4 muscles that originate from scapula and attach to humeral head. Collectively they act to pull humeal head into glenoid fossa. Gives glenohumeral joint additional stability.

1. Supraspinatus - orginiates from supraspinaous fossa of scapula, attaches to greater tubercle of the humerus. Innervated by suprascapular nerve.
2. Infranspinatus - originates from infraspinaous fossa of scapula. Attaches to greater tubercle of the humerus. Innverated by suprascapular nerve.
3. Subscapularis - Originates from subscapular fossa, on costal surface of the scapula. Attaches to lesser tubercle of humerus. Innervated upper and lower subscapular nerve.
4. Teres minor - Originates from posterior surface of scapula, adjacent to lateral border. Attaches to greater tubercle of humerus. Innervated by axillary nerve.

Question 11

Extrinsic

Answer 11

Superficial:

• Trapezius - broad, flat, triangular muscle. Most superifical of all the back muscles. Originates at the skull, nuchal ligament, and spinous process C7-T12. Attaches to acromion, clavicle, and scapular spine.
• Latissimus dorsi - broad origin, arising from spinous process of T6-T12, iliac crest throacolumbar fascia, and inferior 3 ribs. Inserts at intertubercle groove of humerus.

Deep:

• Levator Scapulae - small strap-like muscle. Begins in neck and attaches to scapula. Orginiates from transverse process of C1-C4 and attaches to medial border of the scapula.
• Rhomboid major - originates from spinour processes of T2-T5. Attaches to medial border of the scapula, between scapula spine and inferior angle.
• Rhomboid minor - originates from spinous processes of C7-T1. Attahces to medial border of the scapula at level of spine of scapula.

Question 12

Major structures of the knee

Answer 12

The knee is a pivotal hinge synovial joint composed of the:

• Patella - kneecap bone. Protects the knee and helps with extension by increasing leverage on the femur.
• Anterior cruciate ligament - prevents tibial from moving too far forward. Attaches from lateral condyle of femur to anterior tibia.
• Poserir cruciate ligament - pevents tibia from moving too far backwards. Attaches from medial condyle of femur to posterior tibia.
• Medial collateral ligament - provides stability to inner part of knee. Prevents femur from sliding from side-to-side
• Lateral collateral ligament - provides stability to outer part of knee and helps prevent femur for side-to-side.
• Meniscs (medial and lateral) - Semilunar fibrocartilaginous discs that increase the surface area of the knee and act as shcik absorbers to evenly disperse weight across the entire knee.

Question 13

Articulating surfaces of the knee

Answer 13

• Tiobiofemoral - medial and lateral condyles of the femur articulating with tibial condyles.
  
  • Weight-bearing joint of the knee
• Patellofemoral - anterior aspect of the distal femur articulating with the patella.
  
  • Allows tendon of quadriceps femoris to be inserted directly over the knee.

Question 14

Important bursa of the knee

Answer 14

• Suprapetalla Bursa - Extension of the synvoial cavity of the knee. Located between quadriceps and femur
• Prepatella bursa - located between apex of petella and skin
• Infrapatella bursa - split into deep and superficial. Deep lies between tibia and patella ligament. Superifical lies between petalla ligament and skin.
• Semimembranosus bursa - located posteriorly in the knee joint between the semimembranosus muscle and medial head of gastrocneumius.

Question 15

Movements of the Knee

Answer 15

• Extension - produced by quadriceps femoris, which inserts into tibial tuberosity
• Flexion - produced by the hamstrings, sartorius, and popliteus
• Lateral rotation - biceps femoris
• Medial rotation (with flexed knee)- semimbranosus, semitendinosus, gracilis, sartoris, and popliteus

Question 16

Medial Collateral Ligament Injury

Answer 16

• Very common ligament injury of the knee
• Occur frequently in athletes, especially those involved in sports that require sudden changes in direction and speed. And in patients struck on the outside of the knee.
• Mechanism of injury:
  
  • Valgus stress on the knee, often with tibial external rotation.
  • Knee is forced into hyperextension - can cause injury to multiple ligaments.
• Physical exam:
  
  • Valgus stress test - Knee flexion to 30⁰ and apply valgus force to lower leg as you stabilize the knee. Increase laxity and pain in MCL is a positive test.
    *

Question 17

Lateral Colateral Ligament Injury

Answer 17

• Least common knee injury
• Mechanism of injury:
  
  • Usually occurs in association with multi-ligament injury that involves high energy force hyperextension and varus.
  • If isolated, generally caused by a varus force.
• Physical exam:
  
  • Varus stress test - knee flexion to 30⁰ and apply a varus force to lower leg as uou stabilize the knee. Increased laxity and pain in LCL is a positive test.

Question 18

Anterior Cruciate Ligament Injury

Answer 18

• Important stabilizing ligament of the knee that is frequently injured by athletes and trauma victims.
• Most commonly injured ligament of the knee.
• Women are more likely to injure their ACL.
• Mechanism of injury:
  
  • Person changes direction or pivots or lands in a way that involves rotation or lateral bending.
  • Valgus position of the knee, minimal knee flexion, and internal rotation of tibia.
  • Direct blow causing hyperextension or valgus deformation of the knee.
• Physical exam:
  
  • Anterior drawer test - put knee in flexion to 90^0. Stabilize distal tibia (sit on patients foot). Grasp the proximal tibia with thumbs on either side. Provide an anterior force to pull tibia forwad. Excess displacement is a positive test.
  • Lachmans test - Put knee in flexion to 90⁰. Stabilize femur with on hand, while you grasp upper tibia with other hand. Try to pull upper tibia forward. Excess displacement is a positive test.

Question 19

Posterior Curciate Ligament Injury

Answer 19

• PCL is the primary restraint to posterior translation of the tibia.
• Most PCL injuries occur in combination with other internal derangements with multi-ligament trauma.
• Mechanism of injury
  
  • direct blow to anterior knee
  • Fall on flexed knee while foot is plantarflexed
• Physical exam:
  
  • Posterior drawer test - put knee in flexion to 90^0. Stabilize distal tibia (sit on patients foot). Grasp the proximal tibia with thumbs on either side. Provide posterior force to push tibia backwards. Excess displacement is a positive test.

Question 20

Meniscal Injury

Answer 20

• Meniscal injuries of the knee are common
• Most often occur with twisting injuries (acute); but chronic degnerative tears occur in older patients and can occur with minimal twisting or stress.
• Mechanism of injury:
  
  • Acute meniscal tear typically occur when a person changes direction in a manner that involves rotating or “twisting” the knee while the knee is flexed and the corresponding foot is planted - places a compressive, rotational, and shear stress on the meniscus.
• Presentation - degree of pain at time of injury is variable. Most patients with small tear can continue to partake in activity that caused injury. May experience tearing or popping sensation at time of injury. Acute event is followed by insidious onset of pain and swelling over 24hrs that is made worse by twisting or pivoting movements. Patients with untreated tear can present weeks after the injury complaing of popping, locking, catching, and knee “giving out”.
• Physical exam:
  
  • McMurrays test - Externally rotate the foot and apply a varus force on lower leg when extending the knee (medial tear). Internally rotate the foot and apply a valgus force to check for lateral tear.
  • Apley’s compression test - with patient prone apply a downward pressure while rotating the lower leg internally and externally. Apply a varus force for the medial meniscus and a laternal force for the lateral meniscus. Pain or “popping” indicates a positive test.

Question 21

Joints

Answer 21

• Points where two or more bones articulate
• There are three types of joints
  
  1. Fibrous joints - bones involved are bound by tough, fibrous tissue. No joint cavity is present. Generally immovable. Ex. Sutures - between plate like bones of skull; Gomphosis - “peg-in-socket” joints, teeth; Syndesmoses - bones held together by interosseous membrane. Key in providing strength along length of long bones, middle radio-ulnar joint.
  2. Cartilaginous - bones are attahced by fibrocartilage or hyaline cartilage. Lack a joint cavity. Ex. Primary - Bar of hyaline cartilage units bone, joint between diaphysis and epiphysis of growing long bone; Secondary - Can involve hylaine cartilage or fibrocartilage. Designed for strength with flexibility, pubic symphysis.
  3. Synovial - joint filled with synovial fluid. These joints tends to be fully movable. Synovial fluid id formed in synovial membrane. Articulating bones are separated by fluid-containg joint cavity. Movements may be in 1, 2, or 3 planes and joints are sub-classified as uni-axial, non-xial, and multiaxial.

Question 22

Types of Synvoial Joints

Answer 22

• Hinge - Pemits flexion-extension. Ex. elbow
• Pivot - Permits rotation, pronation-supination. Ex. proximal radio-ulnar joint.
• Gliding - Permits gliding or sliding movements ex. acrominoclavicular joint.
• Saddle - Permits flexion-extension, Ab and Ad-duction, opposition. EX. MCP joint of thumb.
• Ellipsoid - Permits flexion-extension, Ad-Ab-duction. Ex. MCP joint of fingers.
• Ball and socket - Permits flexion-extension, Ad-Ab-duction, medial-lateral rotation, and circumduction

Question 23

Osteoarthritis

Answer 23

• Most common type of arthritis where protective cartilage around joints wears down. Most commonly affects hands, knees, hips, and spine.
  *

Question 24

Common changes seen in OA

Answer 24

1. Articular cartilage - Primary function is to provide a smooth, low-friction, surface to allow for gliding motion of joint. Early changes in OA are commonly seen at articular cartilage. Cartilage swells as collagen network loosens allowing hydrophilic proteoglycans to attract water and expand. Chondrocytes, which are normally dormant, dramtically increase in activity level and proliferation and from clusters, likely in reponse to matrix loss. As OA progresses, matrix degradation continues due to continued production of proteases driven by proinflammatory cytokines and fragements of matrix proteins that further stimulate chondrocytes to produces more cytokines and proteases.
2. Bone - see thickening of subchondrial bone due to increased production of callagen that is improperly mineralized. Osteophytes form at joint margins, often at insertion sites of ligaments or tendons. In more advance disease may see bone cysts.
3. Synovium - most people with symptomatic OA will show some degree of synovitis and/or synovial hypertrophy. Synovitis is not thought to be an initiating factor, but it does contributes to pain and disease progression.
4. Soft tissues - Soft tissues componetns of the joints - ligaments, joint capsule, and menisci (knee), are commonly affected. See disruption in extracellular matrix and loss of cells. Thickening of joint capsule and osteophytes contribtes to enlargement observed in OA joints. May see tears in ligaments and meniscus due to dengernative changes.

Question 25

Clinical Manifestations of OA

Answer 25

• Primary Symptoms - joint pain, stifness and locomotor restriction.
  
  • Tend to present in only a few joints.
  • May see sequelea such as muscle weakness and poor balance.
• Pain - worse with joint use and relieved by rest. Generally goes through 3 stages.
  
  1. Sharp pain brought on by activity. Little impact on function.
  2. More constant pain. Afffects daily acitivity. May experience stifness.
  3. Constant dull/aching pain with periods of unpredictable intense pain. Significant impact on fucntion.
• Joint line tenderness
• Reduced ROM - both active and passive. Generally due to marginal osteophytes and capsular thickening.
• Bony swelling - due to osteophytes and remolding of bone and cartilage.
• Joint deformity
• Instiability

Question 26

Imaging in OA

Answer 26

• Generally, diagnosis of OA is given via clinical presenation. However, imaging may sometimes be used.
• Radiography - can show presence of osteophytes, joint space narrowing, subcondral sclerosis, and cysts. However, changes generally cannot be seen early in disease course.
• MRI - Can detect changes early in disease course better than radiography.
• Ultrasound - used in detection os synovial inflammation, effusion, and osteophytosis.

Question 27

Clinical Diagnosis of OA

Answer 27

• Can be diagnosed clinically if the following are present:
  
  • Persistent usage related joint pain in one or a few joints
  • Age ≥ 45
  • Morning stifness ≤ 30 mins

Question 28

Treatment of OA

Answer 28

• Nonpharmological - weight management, exercises, braces (if appropriate), eduction, use of assitive devices (if appropriate).
• Pharmological - Should only be used if nonpharmologicals are found to be ineffective and should only be used during symptomatic periods.
  
  • Topical NSAIDs - can be used when only a few joints are affected.
  • Oral NSAIDs - when topicals are ineffective, when multiple joints are effected, or when OA affects the hip.
  • Duloxetine - when NSAIDs are contraindicated or ineffective.
  • Topical Capsaicin - used when few joints are involved and other treatmetns are contraindicated. Use tends to be limited due to local side effects.
  • Surgery - hip and knee replacements can be considered when more conservative treatments are ineffective.

Question 29

Major types of meniscal tears

Answer 29