Joints

Question 1

Synovial joints

Answer 1

most appendicular joints
hyaline cartilage
smooth and self-lubricating
connected by fibrous capsule
contains synovial fluid
more movement but less stable

Question 2

Syndesmosis joint

Answer 2

two bones bound by fibrous tissue only

e.g. skul, ankle (tibia-fibula)

Question 3

Synchondrosis joint

Answer 3

two bones bound by cartilage
e.g. physis - between diaphysis and epiphysis during bone growth
can be pathologic, failur eto ossify

Question 4

Synostosis

Answer 4

joint obliterated by growth of bony union
e.g. fusion of pelvis
can be pathologic

Question 5

Symphysis

Answer 5

Opposing surfaces of joitn covered by cartilage
minimal movement, no synovial fluid
e.g. pubic symphysis, intervertebral discs

Question 6

Gomphosis

Answer 6

joint between tooth and socket
fibrous connection between tooth and socket
blood vessels and nerves cross joint

Question 7

Sesamoid bone

Answer 7

bones that increase the mechanical advantage of a tendon
better at compression than tendon tissue
e.g. patella

Question 8

Ligament

Answer 8

thickening of fibrous capsule around the joint to form a band of tissue that resists a specific motion

Question 9

Tendons

Answer 9

Connects muscle to bone, crosses joint
responsible for force transmission to cause movement of joint
deals with both tensile + compressive forces

Question 10

Tendon structure

Answer 10

structure is similar to muscle structure

epitenon: covering of outer tendon
- contains blood supply, proprioceptive and sensory neurons

Collagen fibrils –> collagen fibers –> primary fiber bundles –> secondary fiber bundles (fascicles) –> tertiary fiber bundles –> tendon

Type I collagen predominant
proteoglycan matrix
fibroblasts arranged in rows
- few in number
- produce matrix
- communicate through gap junctions

Question 11

Tendinitis

Answer 11

implies inflammation, but rarely happens in reality
does not respond to anti-inflammatories or icing
lack of evidence of inflammatory cells in tendon

Question 12

Diseased tendon

Answer 12

disordered arrangement of collagen
increased cellularity (myofibroblasts)
increased matrix protein
increased vascularity
absence of inflammatory cells
apoptosis of tenocytes

Question 13

Tendinopathy

Answer 13

“tendon problems”
includes:
Tendinosis - degeneration of tendon without evidence of inflammation
- better term than tendinitis
- started by increased demand on tendon
- without adequate repair - leads to tenocyte death, further exacerbating inadequate collagen and matrix production, which predisposes the tendon to further injury
- partial rupture
- paratenonitis: inflammation of paratneon (material between tendon and its sheath)

Question 14

Tendinopathy imaging

Answer 14

US
good for differentiating rupture and teninopathy
image does not correlate to symptom severity

Question 15

Tendinopathy management

Answer 15

Rest

• collagen repair takes a long time
• advanced by the time pain is felt
• 2-3 weeks before strengthening
• combine with biomechanical deloading - braces, taping

Address predisposition

• running posture
• flexibility
• changes at work

Strengthening

• eccentric strengthening is the most effective
• accelerates tenocyte metabolism
• important component of healing + improvement

Treatment

• NSAIDs - limited use due to lack of inflammation, can use in paratenonitis, bursitis, no evidence for benefit in tendinopathy
• surgery: last resort, long rehab period, does not stimulate collagen synthesis

Return to activity

Question 16

Injury to synovial joint

Answer 16

inflammatory response - look at timing of swelling

• immediate: hemarthrosis, fracture/signifcant ligament injury
• delayed: general inflammation

Question 17

Healing of fractures involving joints

Answer 17

high risk for malunion
joints do not tolerate malunion well
can expect post-traumatic arthritis

Question 18

Bone bruise

Answer 18

injury to subchondral bone

correlates with poor outcomes and development of arthritis

Question 19

Healing of synovial injury

Answer 19

becomes hyperplastic
increased blood supply, inflammation of joint lining
synovial fluid contains factors that prevent clotting

Question 20

Ligament healing

Answer 20

extra-articular: fibrin clot

• proliferation of fibroblasts and matrix production (initially type III collagen, then type I)
• contraction of healing tissue (usually doesn’t contract fully; end up with more “give”)

Intra-articular: no fibrin clot due to factors in synovial fluid
- less healing ability

Question 21

Effect of immobilization on joint injury& healing

Answer 21

Less circulation of synovial fluid
Ligaments tighten - restricted ROM
Arthrofibrosis = severe stiffening of joint
usually want to avoid casting
Decreased loading leads to decreased proteoglycans in cartilage matrix (can be restored with use)

Question 22

Spine segment joints

Answer 22

anterior: symphyseal
posterior: synovial

Question 23

GAG chains

Answer 23

CS and KS

Question 24

CS of GAG

Answer 24

larger, superior/carboxyl end
chondroitin sulfate

mature: C-6S
fetal: C-4S
in OA, see some regression to C-4S

Question 25

KS of GAG

Answer 25

keratin sulfate shorter chains, more proximal/amino enriched in glucosamine

Question 26

Ligament injury classification

Answer 26

Grade 1: mild sprain (1-4 mm stretch) Grade 2: moderate sprain/partial tear (5-9 mm) Grade 3: complete ligament tear (>10 mm)