Tendons and Ligaments L3: Pathology and rehabilitation of tendons and ligaments Flashcards
Combination of structure-combination-function on tendons and ligaments
- Tendon & ligament can change their structure and/or composition (and thus their function) in response to changes physiology (maturation, ageing), injury or other disease processes
- If one structure at joint is affected, the total function of the joint will be disrupted
- Rehabilitation should consider behaviour of all the affected structures/ induce adaptation in each structure.
What are the 2 functions of ligaments?
- Strong enough to provide stability
- Flexible enough to permit joint motion
What are the mechanics of injury of ligaments?
- Ligaments fail when tensile loads exceeds capacity
- Often awkward position of landing
- Joint dislocation is often associated with ligament damage
- Abnormal motion between bony articulation predisposes to articular damage ¥ Eg. lateral ankle is common
- Sublaxation = partial dislocation often strain (not torn) ligament
- Collagen fails progressively (ligament) vs rapidly (tendon)
- Grade 1: damage to some collagen fibres
- Ev/inv tears
- Grade 2: more extensive number of fibres damaged
- Grade 3: complete rupture
- More laxity, end feel not from ligament
- Grade 1: damage to some collagen fibres
What are the 3 grades of failure of ligaments?
- Grade 1: damage to some collagen fibres
- Ev/inv tears
- Grade 2: more extensive number of fibres damaged
- Grade 3: complete rupture
- More laxity, end feel not from ligament
Ligament healing is a continuous process? True or false?
True
What are the 3 phases (triphasic) of ligament healing?
- Inflammation
- Swelling
- Proliferation
- Layng down new tissue
- Remodelling
- Collagen fibres in direction of stress
What are the 3 mechanical properties of ligament healing?
- Decreased stiffness (lower slopes)
- Decreased load at failure (all times)
- Altered site of failure (entire ligament is weakened)
What are the 3 morphology properties of ligament healing?
- Increased cross-sectional area (all times)
- Progressive decrease in CSA from 3-14wks
- Increased laxity at 3, 6, and 40wk
When should extra-articular ligament (outside capsule) be operated on?
- High healing capacity
- Often treating conservatively
- Eg. ankle, collateral ligaments of knee/elbow
When should intra-articular ligament (inside joint) be operated on?
- Lower healing capacity
- Often require surgery
- Eg. ACL, PCL , scapholunate ligament (wrist)
Ligaments are associated with…
- Instability (increased ROM)
- Bony bruising (bone on bone interaction)
- Osteoarthritis (if ligament damage remains, or ligament not healed properly)
What are 3 questions that should be asked in regards to rehabilitation?
- What structure is damaged & to what extent? (grade level)
- What is the timeframe of healing response?
- What are the priorities at this timepoint?
- Inflammation?
What are 4 characteristics of a normal ligament?
- Hypocellular ( decreased cell density)
- Hypovascular ( decreased blood)
- Highly organised
- Dense collagen structure
What are processes that occur during injury, on a time line?
What are processes that occur during injury, at 10 days?
Defect filled with vascular inflammatory tissue
What are processes that occur during injury, at 3 weeks?
inflammatory cells subsided and active fibroblasts dominated
What are processes that occur during injury, at 6 weeks?
decrease in number and size of fibroblasts + some evidence of longitudinal alignment of nuclei (along long axis of ligament)
What are processes that occur during injury, at 14 weeks?
remodelling – increased realignment and decreased cell numbers
What are processes that occur during injury, at 14-40 weeks?
few changes noted; cells remained larger and more numerous
What are the 3 mechanical properties of ligament healing?
- Mechanical properties of healing MCL substance remain inferior to normal ligament (sham surgery) for up to one year
- MCL may increase stiffness by increasing CSA of healing ligament by as much as 2 ½ times normal size
- Healed ligaments are generally more bulky and not as strong as native tissue
What are the 3 functions of tendons?
- Transmit tensile forces
- Mechanical properties of tendon affect muscle function (force generating capacity + muscle length-tension relationship)
- Storage & release of energy for efficiency
- Buffering, amplifying role
What are 11 mechanism for tendon injury?
- Excessive force
- Repeated overload
- Normal forces applied to weakened tendon
- Stress-shielding
- Even if whole tendon is exposed to normal mechanical loading, some fibres may be underloaded (stress-shielded) and other fibres over-loaded
- Eg: Lower strain in proximal posterior part of healthy patellar tendons
- Forces applied in alternative direction o Tendon compression frequently contributes to insertional tendinopathy
- eg: Achilles or Gluteus medius tendons
- Ageing
- Adiposity
- mechanical loads + systemic effects
- Physical activity levels
- spikes in acute load relative to chronic loads
- Diseases
- e.g. diabetes, rheumatoid arthritis
- Medications
- e.g. corticosteroids - suppresses fibroblastic reaction and inhibits growth
- Alcohol
- inhibits fibroblast proliferation
- Degenerative changes may weaken the tendon’s mechanical properties predisposing to injury
- 97% of ruptured Achilles tendons had asymptomatic (didn’t feel) degenerative changes
Where are the 3 places that overuse tendinopathy can occur?
- Midsubstance (red) (e.g. Achilles)
- Insertional (blue) (e.g. Achilles, lateral elbow (tennis elbow), patellar tendinopathy
- Musculotendinous junction (e.g. hamstrings, quadriceps tendon)
What are characteristics of an overuse tendinopathy?
- Grey and amorphous to naked eye
- Disorganised collagen (separation, fragmentation, disorientation)
- Inflammatory & immune cells absent
- cellularity
- Hypervascularity
- proteoglycans and water content
What are characteristics of a normal tendon?
- Highly organised, relatively few cells
- Glistening white
What are some changes in mechanical properties in tendons?
- Reduced Achilles tendon stiffness in Achilles tendinopathy
Why would ultrasound imaging be used in tendinopathy?
- Demonstrates tendon thickening, hypoechoic areas, tears (B-mode)
- Neovessels (Doppler)
___ sensitivity and ____ specificity for diagnosis of tendinopathy = negative ultrasound = useful to rule out tendinopathy
High; low
There is a limited correlation with pain severity in tendinopathy? True or false
True
What are some changes in elastic properties?
- A and P tendinopathy subject had lower Achilles tendon elastic modulus and higher patellar tendon elastic modulus.
- General rule- higher velocity = increased stiffness
What is one of the most critical components of rehabilitation for tendinopathy?
Exercise
Why is exercise a critical rehab option for tendinopathy?
- Isometric exercise possibly superior ?
- Improve function
- Progressive loading to remodel tendon
- Avoid compressive loading, especially if insertional
- (eg: prox hamstrings)
- Considerations…
- What is the loading history ?
- Gradual progression of loads
- Address stability/coordination
- No quick fixes (slow turnover)
What is paratendinitis?
- Occurs where a tendon rubs over a bony protuberance
- De Quervains (APL, EPL)
- FHL (near medial maleolus)
- Acute oedema, hyperaemia of paratenon
- Inflammatory cells
- Tendon itself minimally involved
- Crepitis (fibrinous exudate fills shealth)
What is a tendon rupture?
- Can occur in normal tendon if loads are sufficiently large
- Common tendons
- Rotator cuff (older adults)
- Achilles (young, active adults)
- More commonly occurs in tendon weakened by pre-existing degenerative change (diabetes, alcohol)
How to assess tendon pathology?
What are the effects of immobolisation on tendons and ligaments?
- decreased structural properties of tendons/ligaments
- Immature, weaker, disorganized collagen
- decreased tissue stiffness up to 50% after 8 weeks of immobilisation
- Tissue deterioration is less if immobilised in some tension
What are the effects of remobilisation and recovery?
- Re-establishment of normal stresses can reverse effects, but …
- Tendons/ligaments are relatively hypovascular + hypocellular
- Healing is slow - takes many months and may never attain past characteristics
- Insertion sites are more resistant to recovery
What are some exercise training concepts to understand as rehabilitation?
- Progressive loading to improve tendon “capacity”
- Increased strength = increased energy storage = store and release
