Growth & Repair Flashcards
Describe the parts of a long bone?
Diaphysis - Shaft
Metaphysis - Flare at the end of the shaft before epiphysis, contains growth plate
Epiphysis - Joint-end of the bone, after the epiphyseal plate
Medullary Cavity - Inside diaphysis, full of marrow
Whats the structural difference between cortical and cancellous bone?
Cortical is made of cylindrical osteons of concentric lamenae. They contain central canals of veins/arteries.
Spongy Bone contains marrow
What is the geographical difference between compact and spongy bone?
Cortical bone is found in the diaphysis of long bones
Trabecular is found in the metaphysis & growth plate of long bones
What is the functional difference between cortical and cancellous bone?
Compact resists bending & torsion
Cancellous resists compression
What are the stages of fracture repair?
1) Inflammation
2) Soft Callus
3) Hard Callus
4) Bone Remodelling
How might we intervene in stage 1 of fracture repair?
Inflammation
- NSAIDS for inflammation (there is debate as to whether they help the pain more or delay healing more)
- Plate Concentrates to improve healing e.g. Platelet derived growth factor (PDGF), IGF & VEGF
What is the soft callus stage of fracture repair?
The inflammation/swelling goes down
Cartilage and fibrous tissue start to unite the bony fragments.
It gives back some stability but angulation ca still occur
What interventions are possible for stage 2 of fracture healing?
- Cartilage replacement with DMB (Demineralised Bone Matrix)
- Bone Graft
- Bone substitutes
Describe the types of bone graft?
Autogenous Cancellous Bone Graft (Gold standard). IS both osteoconductive and inductive.
Allograft - Osteoconductive but not inductive and risks transmission of disease
What happens during the 3rd stage of fracture repair?
Cartilage forms into woven bone
What happens during the 4th stage of fracture repair?
Woven bone forms into lamellar bone and the medullary canal is reconstituted
How is strain involved in fracture repair?
Mechanical strain induces tissue differentiation so if strain is too low you don’t grow fresh bone
If its too much then the healing process is interrupted
Describe the structure of a peripheral nerve?
Axon sheathed in endoneurium
Axons grouped into fascicles sheathed in perineurium
Fascicles grouped into a nerve sheathed in epineurium
In what situations might a peripheral nerve become entrapped?
Median nerve during carpal tunnel syndrome
Spinal root during intervertebral disc prolapse (i.e. sciatica)
Digital nerve in 2/3rd web spaces of foot during morton’s Neuroma
What are the different types of nerve trauma?
Direct (blow or laceration) vs indirect (Avulsion vs traction)
What is neurapraxia?
a temporary loss of motor/sensory function due to:
- Stretch/bruise –> Local ischaemia & Demyelination
Prognosis for neurapraxia?
Reversible, symptoms usually last 6-8wks
What is axonotmesis?
Damage to a nerve axon but not the sheath
Stretch/crush/direct blow leads to wallerian degeneration
Whats the prognosis for axonotmesis?
Fair but worse than neurapraxia
Usually good but not full sensory recovery and less motor recovery
Whats is Neurotmesis?
Completely divided axon and sheath due to laceration or avulsion
Prognosis for Neurotmesis?
Poor. Can only recover with suturing & grafting
Plus theres a high risk of miswiring during regeneration
Clinical features of peripheral nerve injury?
Dysaesthesia
Paresis/paralysis +/- wasting
Dry skin
Diminished/absent reflexes
UMN/LMN signs
Describe the process of nerve healing?
Distal axon dies via wallerian degeneration
Then proximal axonal budding occurs after roughly 4 days and the nerve regenerates at ~1mm/day
How do you assess the healing of a nerve?
Nerve conduction studies
Tinel’s Sign - Tap over a nerve, you will feel paraesthesia as far distally as the regeneration has spread
What methods are there for repairing a nerve injury?
Bundle repair & growth factor when no tissue is lost
Nerve grafting when nerve is lost
Describe the surgical rule of 3?
Immediate surgery within 3 days for clean/sharp injuries
Early surgery within 3 wks for blunt/contusion injuries
Delayed surgery after 3 months for closed injuries if there’s no recovery
What cells make up tendons
A longitudinal arrangement of cells, mainly tenocytes.
Describe the arrangement of collagen in a tendon?
Mostly type 1 collagen bundle surrounded by endotendon.
Bundles arranged into fascicles surrounded by paratendon
Fascicles bundled into a tendon surrounded by epitendon
What happens if a tendon is underused?
Immobility leads to a low water & glycosaminoglycan concentration
This leads to poor strength
List some tendon pathologies?
Degeneration
Inflammation
Enthesiopathy
Traction Apophysitis
Avulsion +/- bone fragment
Tear
Laceration/Incision
Example of a degenerative tendon disorder and presentation?
Intrasubstance Mucoid Degeneration - common in the achilles
Can be asymptomatic but may be swollen, painful or tender
Example and presentation of an inflammatory tendon disorder?
De Quervain’s Stenosing Tendonitis
Tendons of the EPB & APL get swollen, tender, hot and red. +ve for finklestein’s test
What is enthesiopathy?
Inflammation at the insertion of a tendon to bone or muscle
E.g. Lateral Humeral Epicondylitis aka tennis elbow
Whats an example of a traction Apophysitis?
Osgood Schlatter’s Disease
A recurrent load in adolescent active boys leads to inflammation at the patellar tendon as it inserts onto the Ant. Tibial Tuberosity
How do we treat an avulsion?
Conservative - Retraction
Operative - Reattachment & fixation of the bone fragment
What are the types of tendon tear?
Intrasubstance e.g. achilles
Or at Musculotendinous junction
When does an achillis tear and how do we tell?
Most happen when sprint starting or jumping. Weight bearing forefoot push off whilst extending the knee.
+ve simmonds squeeze test and a palpable tender gap
How do we treat a tendon tear?
Conservative - Mobilise + splint/cast
Operative - If the ends can’t be opposed
Whats the function of a ligament?
to provide joint stability whilst maintaining ROM
Attached to bone on either side of a joint
Compare a tendon to a ligament?
Ligaments have:
- Less collagen
- More proteoglycans/water
- Less organized collagen
- Rounder fibroblasts
Describe the structure of a ligament?
Type 1 collagen
Fibroblasts
Sensory fibres that carry proprioception, stretch & sensory
What are the phases of ligament rupture healing?
1) Haemorhagic Phase
2) Proliferative Phase
3) Remodelling Phase
What happens during the haemorrhagic phase of ligament healing?
First a blood clot that is then resobed & replaced by Heavy Cellular Infiltrate
What happens during the proliferative phase of ligament healing?
Scar tissue forms (disorganised collagenous CT)
What happens during the remodelling phase of ligament healing?
Matrix becomes more ligament like
When would we care for a ligament rupture conservatively?
A partial rupture with no instability
Or a patient that isn’t fit for surgery
When would we care for a ligament rupture operatively?
If theres instability, expectation e.g. sportsmen or multiple ruptures
How would we operatively treat a ligament rupture?
Repair
Augmentation
Replacement
Name reasons for a delayed union? (delayed healing of a fracture)
- High energy Injury
- Instability
- Infection
- Steroids/immunosuppressants
- Smoking
- Warfarin
- NSAIDS
- Ciprofloxacin
- Age
- Radiotherapy
Name some results of a non-union (complete failure of healing)
Instability
Calcification
Abundent calluses
Pain/tenderness
Persistant fracture line
Bone sclerosis
