9: MSK Growth Injury and Repair - Ligament, Tendon and Bone Flashcards
what are ligaments composed of?
- collagen fibres (type 1)
- fibroblasts (communicate)
- sensory fibres; proprioception, stretch, sensory
- vessels (surface)
- crimping (allow stretch)
compared to tendons, ligaments have…
- lower % of collagen
- higher % of proteoglycans and water
- less organised collagen fibres
- rounder fibroblasts
what is the treatment for a ligament rupture/tear?
conservative:
- partial
- no instability
- poor candidate for surgery
operative:
- instability
- expectation (sportsmen)
- compulsory (multiple)
describe the structural anatomy of a tendon
- longiudinal arrangement of cells (mostly tenoxytes) and fibres (collagen type 1 - triple helix)
- fascicles of long narrow spiralling collagen bundles
- collagen bundles covered by endotenon
- fascicles covered by paratenon
- tendon covered by epitenon
what layer of a tendon is the blood supply found?
fine network of blood vessels in paratenon
give an example of where a tendon sheath is found?
flexor tendons in distal palm and fingers
tendons are connected to tendon sheath by what?
vincula
what is the function of a tendon?
- to be flexible and very strong when under tension
list some causes of tendon injury
- degeneration
- inflammation
- enthesiopathy
- traction apophysitis
**- avulsion +/- bone fragment - tear - intrasubstance (rupture)**
- tear musculotendinous junction
- laceration/incision
- crush/ischaemia/attrition
- nodules
what is de Quervain’s stenosing tenovaginitis?
- inflammation of extensor pollicus brevis EPB + adductor pollicus longus APL passing through common tendon sheath at radial aspect of wrist.
- presents with swollen, tender, hot, red wrist
- positive Finkelstein’s test
what is enthesiopathy?
give examples
- inflammation at insertion of muscle/tendon or ligament to bone.
- muscle/tendon: usually at muscle origin rather than tendon insertion e.g. lateral humeral epicondylitis (tennis elvow) - common extensor origin
- ligament: plantar fasciitis
describe traction apophysitis, e.g. Osgood-Schlatter disease
- Osgood-Schlatter disease is a self-limited condition characterized by inflammation and stress-induced injury of the tibial tuberosity at the insertion point of the patellar tendon.
- It typically affects adolescents and is associated with high levels of physical activity, particularly in sports that involve running, jumping, or rapid changes in direction.
what is the treatment of tendon avulsion +/- bone fragment?
- conservative: limited application, retraction tendon
- operative: reattachment tendon > through bone, fixation bone fragment
common mechanisms of tendon intrasubstance rupture
- pushing off with weight bearing forefoot whilst extending knee joint e.g. sprint starts or jumping movements
- unexpected dorsiflexion of ankle e.g. slipping into hole
- violent dorsiflexion of plantar flexed foot e.g. fall from height
clinical features of achilles tendon rupture
- positive Simmond’s (squeeze) test
- palpable tender gap
tendon rupture treatment
conservative:
- mobilise (partial rupture) e.g. med lig knee
- splint/cast
operative:
- if high risk rerupture
- if high activity
- if ends cannot be opposed
list the differences between cortical and cancellous bone
cortical:
- diaphysis
- resist bending and torsion
- laid down circumferentially
- less biologically active
cancellous:
- metaphysis
- resists/absorbs compression
- site of longitudinal growth (physis)
- very biologically active
what is a fracture?
- break in structural continuity of bone
- may be a crack, break, split, crumpling, buckle
why do bones fail?
- high energy transfer in normal bones, takes a lot of energy
- repetitive stress in normal bones > stress fracture
- low energy transfer in abnormal bones e.g. osteoporosis, osteomalacia, metastatic tumour, other bone disorders
what are the four stages of fracture repair?
- inflammation
- soft callus
- hard callus
- bone remodelling
what is the gold-standard for the majority of bone graft needs?
- autogenous cancellous bone graft
- is both osteoconductive and osteoinductive
why is a bone allograft not as effective as a autogenous cancellous bone graft?
- not osteoinductive
- risk of disease transmission
when does the soft callus (second stage) stage of fracture repair begin and end?
- begins when pain and swelling subside
- lasts until bony fragments are united by cartilage or fibrous tissue
what happens during stage 3 (hard callus) of fracture repair?
- conversion of cartilage to woven bone
- in a typical long bone fracture: endochondral bone formation and membranous bone formation.
what happens during stage 4 (bone remodelling) of fracture repair?
- conversion of woven bone to lamellar bone
- medullary canal is reconstituted
- bone responds to loading characteristics Wolff’s law
describe the importance of strain in fracture repair
- degree of instability is best expressed as magnitude of strain (% change of initial dimension)
- if strain is too low mechanical induction of tissue differentiation fails
- too high and healing process does not progress to bone formation
what is a delayed union fracture?
failure to heal in expected time
list some causes of a delayed union fracture
- high energy injury
- distraction (increased osteogenic jumping)
- instability
- infection
- steroids
- immune suppressants
- smoking
- warfarin
- NSAID
- ciprofloxacin
causes of a non-union/failure to heal fracture
- failure calcification fibrocartliage
- instability - excessive osteoclasts
- abundant callus formation
- pain + tenderness
- persistent fracture line
- sclerosis
