Musculoskeletal Growth/Injury and Repair Flashcards
What is a ligament?
Dense bands of collagenous tissue which span a joint, being anchored to bone at either end
Ligament structure
Type I collagen fibres Fibroblasts (communicate) Sensory fibres - proprioception - stretch - sensory Vessels (surface) Crimping allow stretch
Compared to tendons, the composition of ligaments have….
Lower % of collagen
Higher % of proteoglycans and water
Less organised collagen fibres
Rounder fibroblasts
What happens to cause a ligament rupture?
Forces exceed strength of ligament
Stages of healing a ligament injury
- haemorrhage (blood clot)
- Proliferative phase (production of scar tissue)
- remodelling (matrix becomes more ligament like)
Treatment of ligament injuries
Conservative if - partial injury - no instability - poor candidate Operative if - instability - expectation (sportsmen) - compulsory (multiple) Repair Augmentation Replacement
What does the muscle/tendinous composite unit consist of?
Muscle origin from bone
Muscle belly
Musculotendinous junction
Tendon (+/- sesamoid bone, +/- tendon sheath)
Tendinous insertion into bone (sharpeys fibres)
What arrangement do the cells of tendons have?
Longitudinal arrangement of cells (tenocytes)
Fibres (collagen type I - triple helix)
Function of tendons
Flexible and very strong in tension
Movement
What is an enthesiopathy?
Inflammation at insertion to the bone
What condition is enthesiopathy at a ligament?
Plantar fasciitis
Another name for lateral humeral epicondylitis
Tennis elbow
What does mallet finger present with?
Forced flexion of extended finger
Pathology of mallet finger
Tear of extensor tendon into dorsum of base of distal pharynx of finger
What test is done for an achilles tendon tear?
Simmonds squeeze test - palpable tender gap
Possible mechanisms of tendon rupture/tear
Pushing off weight bearing forefoot whilst extending the knee joint e.g. sprint starts or jumping movements (53%)
Unexpected dorsiflexion of ankle e.g. slipping into a hole (17%)
Violent dorsiflexion of plantar flexed foot e.g. fall from a height (10%)
Treatment of tendon rupture/tear
Mobilise (partial rupture)
Splint/cast
Operative
What combines to form a spinal nerve?
Anterior and posterior roots
What are peripheral nerves?
The part of a spinal nerve distal to the nerve roots
Function of C fibres
Dull, aching, burning pain
temp
sensation
What is carpal tunnel syndrome?
Compression of the medial nerve at the wrist
What is sciatica?
Compression of the spinal root by intervertebral disc
What is mortons neuroma?
Compression of digital nerve in 2nd or 3rd webspace in forefoot
Pathology of neurapraxia
Nerve In continuity, stretched or bruised
Reversible conduction block - local ischaemia and demyelination
Presentation of neurapraxia
Local ischaemia
Local demyelination
Prognosis of neurapraxia
Good - weeks or months
Pathology of axonotmesis
Endometrium intact (tube in continuity) but disruption of axons - more severe injury Extremely stretched or crushed or direct blow
Presentation of axonotmesis
Wallerian degeneration
Prognosis of axonotmesis
Sensory recovery often better than motor
Often not normal but enough to recognise pain, hot and cold, sharp and blunt
Pathology of neurotmesis
Complete nerve division
Laceration or avulsion
Endoneural tubes disrupted
Prognosis of neurotmesis
poor
no recovery unless repaired (direct suturing or grafting)
endonueral tubes disrupted so high chance of “miswiring” during regeneration
Can peripheral nerves regenerate?
yes
What nerve injuries are closed fractures related to?
Nerve injuries in continuity e.g. neuropraxis, axonotmesis
Treatment of nerve injury after closed fracture
Spontaenous recovery is possible
Surgery indicated after 3 months (if no recovery is indicated after clinical or EMG)
Examples of nerve injuries in closed fractures
Brachial plexus injuries
Radial nerve humeral fracture
What nerve injuries are open fractures related to?
Nerve division e.g. neuromeric injuries by knife/glass
Treatment of nerve injury by open fracture
early surgery
in open nerve fractures, how long is it after the injury when the distal portion of the nerve undergoes Wallerian injury?
up to 2-3 weeks after the injury
presentation of nerve injuries
dysaesthesia - anaesthetic (numb) - hypo and hyper aesthetic - paraesthetic (pins and needles) Paresis or paralysis +/- wasting dry skin diminished or absent reflexes
Definition of dysesthesia
Disordered sensation
Definition of paresis
Weakness
Why would a nerve injury cause dry skin?
Loss of tactile adherence since sudomotor nerve fibres not stimulating sweat glands in the skin
How does nerve injury healing work?
Initial death of axons distal to site of injury, then Wallerian degeneration, then degradation of myelin sheath
- proximal axonal budding occurs thereafter 4 days
- regeneration proceeds at a rate of approx. 1mm/day in humans or 3-5mm per day in children
What is the first modality to return in nerve injury?
Pain
What does the prognosis of nerve injury healing depend on?
Wether the nerve is
- pure = only sensory or only motor
- mixed - both sensory and motor component in same nerve
How distal the lesion is - proximal worse
What sign can monitor the recovery of nerve injuries?
Tinels sign
The Rule of 3 - surgical timing in a traumatic peripheral nerve injury
Clean and sharp injuries = immediate surgery within 3 days
Blunt/contusion injuries = early surgery within 3 weeks
Closed injuries = delayed 3 months after injury
Presentation of UMN lesion
Decreased strength increased tone increased deep tendon reflexes Clonus present Babinskis sign present Atrophy absent
Presentation of LMN lesion
Strength decreased Tone decreased Decreased deep tendon reflexes Clonus absent Babinskis sign absent Atrophy present
Definition of a fracture
Break in the structural continuity of bone
How can a fracture happen?
High energy transfer in normal bones Repetitive stress in normal bones - stress fracture Low energy transfer in normal bones - osteoporosis - osteomalacia - metastatic tumour
4 stages of fracture healing
- inflammation
- soft callus
- hard callus
- bone remodelling
When does inflammation start after a fracture?
Immediately
When does the soft callus occur after a fracture?
When the pain and the swelling subside
What is the hard callus formation?
Conversion of cartilage to woven bone
What is bone remodelling?
Conversion of woven bone to lamellar bone
Causes of delayed union of bone fracture
high energy injury distraction (increased osteogenic jumping) instability infection steroids immunosuppressants smoking warfarin NSAIDs Ciprofloxacin
What is a significant risk factor for avascular necrosis?
Previous Chemotherapy
What is avascular necrosis?
Death of bone tissue secondary to the loss of blood supply - leading to bone destruction and loss of joint function
Causes of AVN of hip
Alcohol excess
Chemotherapy
Long term steriod use
Trauma
Presentation of AVN of hip
Asymptomatic initially
Pain in joint
Investigations of AVN of hip
MRI - 1st line
Xray (may be normal initially, osteopenia and microfractures may be seen early on
