context week 3 Flashcards

1
Q

what is osteogenesis imperfecta

A

brittle bone disease, defect in maturation and organisation of Type 1 collagen.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what are the two types of osteogenesis imperfecta

A

autosomal dominant- mutliple fractures in childhood, short stature with deformity, blue sclera, loss of hearing

autosomal recessive - rarer, fatal prenatal or associated spinal deformity

(many genetic changes de novo)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what is osteogenesis imperfecta sometimes mistaken for

A

child abuse

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what is shown on X-rays of osteogenesis imperfecta

A

mild cases have relatively normal X-rays with Hx of low energy fractures. [sometimes “psuedofractures”]

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

healing ability of osteogenesis imperfecta

A

fractures tend to heal with abundance but poor quality callus formation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

treatment for osteogenesis imperfecta

A

splintage, traction or surgical stabilisation.

some cases can develop progressive deformity which may require multiple osteotomies and intramedullary stabilisation for correction.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what is skeletal dysplasia?

A

medical term for short stature (Dwarfism not used anymore).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

why does skeletal dysplasia occur?

A

genetic error, abnormal connective tissue/ bone occurs.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what are proportionate and disproportionate statures in skeletal dysplasia?

A

proportionate - limb same size/proportional to spine

disproportionate - limbs and spine not proportional.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what is the commonest skeletal dysplasia? give some features of it.

A

achondroplasia.

autosomal dominant (80% spontaneous disease). lax ligaments and normal mental development. disproportionately short limbs to spine. wide nose, prominent forehead.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

know that there are many other types of skeletal dysplasia each with their own features. (mild/severe signs/consequences/symptoms)

A

-

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

treatment for skeletal dysplasia

A

genetic testing of child and family.

correct deformities and lengthen limbs.

GH therapy may be appropriate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

where is type 1 and 2 collagen found

A

1-bone, tendon, ligaments, skin

2-cartilage

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what are CTDs due to?

A

genetic disorders of collagen synthesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what is generalised (familial) joint laxity

A

CTD. double-jointed people, 5% population, more prone to ankle sprains (soft tissue injury) and painful dislocations (rucurrent shoulder/patellar)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

medical name for double jointedness

A

generalised (familial) joint laxity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

what is marfan’s?

A

CTD. tall, long limbs, ligamentous laxity.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

what genetic abnormality occurs in Marfan’s

A

autosomal dominant/sporadic mutation of fibrillin gene

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

what are some common signs/consquences of Marfan’s

A

lens dislocation, retinal detachment, glaucoma,
high arched palate,
spontaneous pnuemothroax, apical blebs,
pectus excavatum/carinatum.
aortic dissction/aneurysm/regurgitation. mitral valve prolapse/regurgitation.
long arms/legs, scoliosis, arachnodactyly.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

what does EDS stand for and what causes it?

A

Ehlers-Danlos syndrome, heterogenous condition autosomal dominantly inherited with abnormal elastin/collagen formation.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

features of EDS

A

profound joint hyper mobility, vascular fragility, easy bruising, scoliosis, joint instability

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

treatment of EDS

A

bone surgery (wound dehiscence common as abnormal connective tissues)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Down’s syndrome is caused by what genetic problem?

A

trisomy 21.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

features of Downs relating to CTD

A

short stature, joint laxity, possible recurrent dislocation (may require stabilisation), atlanto-axial instability may occur in C-spine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

general background about muscular dystrophies

A

Duchenne muscular dystrophy

rare, X-linked, progressive muscle weakness + wasting

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

DMD cause

A

defect in dystrophin gene involved in calcium transport

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

DMD presentation

A

initially difficulty standing/climbing stairs; Gower’s sign

age 10 can’t walk, age 20 cardiac/resp failure, dead by early 20’s

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

investigtions for DMD

A

inc serum creatinine phosphokinase, abnormalities on muscle biopsy.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

treatment for DMD

A

physio, splintage, deformity correction may inc mobility. correct severe scoliosis by surgery

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

Becker’s MD vs DMD

A

similar to DMD but less severe. able to walk until teens and die 30/40’s

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

upper motor neurone problem causes what?

A

spasticity and hyperreflexia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

lower motor neurone problem causes what?

A

reduced tone and reflexes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

name some neuromuscular disorders

A

cerebral palsy, spina bifida, polio.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

why does Cerebral palsy occur?

A

onset before 2-3 years, due to insult to immature brain (before during or after birth)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

causes of cerebral palsy

A

genetic problem, intrauterine infection in pregnancy, brain malformation, intra-cranial haemorrhage, hypoxia at birth, meningitis, premature birth.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

types of cerebral palsy

A

hemi/di/quadratplegic;

also spastic, ataxic and athetoid(dyskinetic)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

management of cerebral palsy

A

physio, splintage, diazepam, baclofen, botox (botolinem toxin), surgery to correct

((((also SALT’s and carers etc…))))

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

spina bifida cause

A

congenital, two halves of posterior vertebral arch fail to fuse

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

spina bifida types

A

spina bifida OCCULTA (mild) and cystica (severe)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

what is spina bifida occulta?

A

mild = spina bifida OCCULTA. maybe no associated problems but may get tethering of spinal cord and roots.

get high arches feet and clawed tons; some have dimple of hair on back

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

what is spina bifida cystica?

A

severe, herniated contents of spinal canal.
meninges only = meningocele
meninges + spinal cord = myelomeningocele.
may be associated with hydrocelphalus (excess CSF fluid causing inc ICP).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

treating spina bifida cystica

A

close within 48 hours surgically (prevent infection/damage). no treatment for neurological consequences.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

pathogenesis of polio/poliomyelitis

A

viral (poliovirus by faecal-oral route), causing lower motor neurone deficit.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

polio PC

A

systemically unwell then 3-4 days later muscle weakness and inability to move limb/paralysis, recovery possible while some stay damaged

preventable due to vaccine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

polio features and treatment

A

paralysis, joint deformity, growth defects, can still feel/sensory neurones fine

splintage and inc mobility.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

name two developmental disorders

A

limb malformations, obstetric brachial plexus palsy.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

examples of limb malformations

A

extra/absent bones, short bones, fused bones, skin/soft tissue issues.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

what is syndactyly?

A

commonest congenital malformation (failure in apoptosis). leave or may require surgery

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

what is polydactyly and how to treat?

A

extra digit,

amputate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

what is fibular hemimelia, signs and treatment

A

partial/complete absence of fibula

shortened limb, bowing of tibia, ankle deformity

mild= limb lengthening
severe= through ankle amputation + prothesis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q

give examples of other limb shortening deformities

A

deficiency in proximal femur and tibia; radial absence/hypoplasia.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
52
Q

where does congenital fusion occur commonly and what treatment needed

A

commonest between two of the tarsal bones of the foot, may be painful in childhood indicating surgery.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
53
Q

who does obstetric brachial plexus palsy occur in?

A

0.2%, large babies/twins/shoulder dystocia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
54
Q

what is Erb’s palsy and common features

A

commonest obstetric brachial plexus palsy.

injury to C5-C6, reduced innervation in deltoid, supraspinatus, infraspinatus, biceps and brachialis.

leads to internal rotation (unopposed subscapularis) giving “waiter’s tip posture”.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
55
Q

treating Erb’s palsy

A

physic give good prognosis (90% recovery).

surgical release of contractures and tendon transfers if not recovering.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
56
Q

what is Klumpke’s palsy

A

rarer, C8-T1 affected.

forceful adduction which results in paralysis of intrinsic hand muscles +/- fingers and wrist flexors.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
57
Q

Klumpke’s palsy association, treatment and prgonosis

A

possible Horner’s syndrome (disrupt of first sympathetic ganglia from T1).

no specific treatment, 50% recovery

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
58
Q

what is TBP ( total brachial palsy) prognosis

A

TBP after birth carries poorest prognosis of obstetric brachial plexus palsy’s

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
59
Q

what are some normal physical developmental milestones?

A
sits alone/crawls - 6-9moths
stands - 8-12 months
walks - 14-17 months
jumps - 2 years
managed stairs independently - 3 years

(note there is massive variation; missing one milestone is fine)

60
Q

what are some normal near developmental milestones?

A
loss of primitive reflexes - 1-6 months
head control - 2 months
speaking - 9-12 months
eating with fingers/spoon - 14 months
stacks 4 blocks - 18months
understand 200 words (10 a day) - 18/20months
potty trained - 2/3years
61
Q

what is the pattern of normal limb development (lower limb)

A

children go varus to valgus to neutral usually (variation is familial).

62
Q

what is considered pathological variation in lower limb development? how to manage?

A

pathological if considered 6 degrees +/- normal mean value for that age; X-ray and chart monitoring.

majority resolve before age 10, after may require surgery.

check for underlying pathology EG: skeletal dysplasia, Blount’s, rickets…

63
Q

genu varum is what condition and may be caused by what disease?

A

bow-legged

sometimes due to Blount’s disease

64
Q

what is Blount’s disease and how to treat

A

growth disorder of medal proximal tibial physics.

osteotomy

65
Q

what are other (except from Blounts) pathological causes of Genu varum? what can occur as complication of these

A

ricket’s, tumour (osteochondroma), traumatic physis injury, skeletal dysplasia. (non-patholigcal = FHx)

early onset OA can occur

66
Q

What is Genu Valgum and what can it be caused by?

A

knock-kneed.

rickets, tumour (enchondromatosis), trauma, neurofibromatosis or idiopathic

67
Q

what is in-toeing?

A

toes point to the midline, accentuated when running.

‘pigeon toes’

68
Q

what are three causes of in-toeing and their treatments?

A

femoral neck anteversion - normally occurs slightly, excessive less to intoning and Genu Valgum. (no surgery)

internal tibial torsion - bone rotation inward on vertical axis, normal variation (ignore)

forefoot adduction - majority resolve, surgery considered after 7-8years

69
Q

medical name for flat feet?

A

pes planus

70
Q

background information on pes planus

A

20% population, usually no underlying pathology, is normal variation (arch doesn’t form in childhood)

71
Q

development of flat feet to normal arched feet

A

born flat foot, as we walk muscles and arches develop

72
Q

what are the two types of flat feet/pes planus?

A

fixed and mobile/flexible.

73
Q

how to test if fixed and mobile/flexible flat feet?

A

dorsiflexion of big toe to tell difference

74
Q

fixed flat foot may indicate what?

A

pathology (e.g.: underlying inflammatory disorder, neurological disorder or bony abnormality)

75
Q

what are curly toes?

A

minor overlapping of toes with curling (commonly 5th toe).

76
Q

treating curly toes

A

most self-correct, if pain or discomfort in shoes or continuation into adolescents then surgery

77
Q

give examples of paediatric hip problems

A

DDH, SUFE, perthes, transient synovitis of the hip.

78
Q

what does DDH stands for?

A

developmental dysplasia of the hip

79
Q

what is DDH?

A

dislocation/subluxation of the femoral head (0.5% babies, 80% male)

commoner in left hip but 20% bilateral

80
Q

risk factors for DDH

A

FHx, breech position, Down’s, 1st born babies, presence of congenital disorders

81
Q

what happens if left untreated

A

shortened limb, early-onset OA, gait/mobility affected

82
Q

investigations of DDH

A

examine babies shortly after birth; look for shortening, extra skin fold,
click/clunk on Ortoloni/Barlow manoeuvres

US if positive (X-ray cannot be used)

83
Q

what does US of DDH show?

A

dislocated hip, unstable hip or shallow acetabulum.

84
Q

why can x-rays not be used to diagnoses DDH

A

X-rays cannot be used in sound babies as until 4-6months femoral head is unossified.

85
Q

treatment of DDH

A

mild → monitor
severe → palvik harness (95% fix).
older children (18months) → surgery → open education and osteotomy

86
Q

what is transient synovitis of the hip

A

self-limiting inflammation of synovium of the joint (commonest in hip). it is the commonest cause of childhood hip pain

87
Q

what can often precede transient synovitis of the hip

A

URTI (viral)

88
Q

who does transient synovitis of the hip often affect and how?

A

2-10 year-old boys, present with limp and unable to bear weight.

89
Q

PC of transient synovitis of the hip

A

limp and unable to bear weight.

ROM may be resiricted, low grade fever but not septically unwell

90
Q

investigation of transient synovitis of the hip

A
  • radiographs to exclude perches
  • normal CRP may exclude septic arthritis → if doubt aspirate.
  • MRI is proximal femur osteomyelitis is possible.
91
Q

treatment of transient synovitis of the hip

A

once serious pathology excluded → NSAID and rest → resolves in a week

92
Q

PC of perthes disease (or Legg-Calve-Perthes disease)

A

age 4-8 boys, very active boys of short stature.

pain and a limp; most cases unilateral

93
Q

what does bilateral perthes suggest

A

thrombophilia or skeletal dysplasia.

94
Q

why does perthes cause a limp?

A

most cases unilateral → loss of internal rotation then loss of abduction → develop positive Trendleberg test from gluteal weakness

95
Q

pathogenesis of Perthes

A

idiopathic osteochondrosis of femoral head → femoral head transiently loses its blood supply resulting in necrosis (AVN) and subsequent growth abnormalities → subsequent remodelling may lead to collapse → OA → hip replacement in adolescents.

96
Q

investigating and treating Perthes

A

Xray and avoid physical activity, 50% do well, occasionally femoral bone head sublease → osteotomy of acetabulum/femur

97
Q

SUFE stands for what?

A

slipped upper femoral epiphysis

98
Q

Who does SUFE normally affect?

A

overweight pre-pubecent adolescent boys,

99
Q

what is SUFE

A

femoral head slips inferiorly in relation to femoral neck

100
Q

risk factors for SUFE

A

hypothyroidism, renal disease, obesity

101
Q

why does SUFE occur?

A

growth plate is not strong enough to support body weight and femoral epiphysis slips due to strain.

cases can be acute, chronic or acute-on-chronic.

102
Q

PC of SUFE

A

pain in groin or only pain in knees (due to obturator nerve in hip and knee joint)

103
Q

treatment of SUFE

A

urgent surgery to pin femoral head and prevent further slippage. bigger the slip the worse prognosis.

may require THR in late teens.
severe acute = risks AVN.
severe chronic may require osteotomy

104
Q

investigation and findings in SUFE

A

loss of internal rotation of hip is predominant clinical sign.

X-ray changes subtly, lateral view may show slip.

105
Q

what you need to remember in paediatric and adolscent knee problems?

A

examine hip

106
Q

common examples of paediatric and adolscent knee problems

A

extensor mechanism problems, adolescent knee pain, patellar instability, Osteochondritis dissecans, meniscal problems.

107
Q

who gets extensor mechanism problems?

A

common in adolescents (inc body weight and excersise).

108
Q

patellar tendonitis overview and treatment

A

patellar tendonitis (jumpers knee) is self-limiting → rest and physio

109
Q

what is apophysitis?

A

inflammation of growing tubercle when tendon attaches, occurs at either end of tendon.

110
Q

what are the two types of apophysitis?

A

Osgood-schlatter disease - inflamed tibial tubercle

Sinding-larsen-johansson disease - inflamed inferior pole of patella

treatment = rest and physiotherapy, may be left with bony prominence (not require surgery)

111
Q

adolescent knee pain overview and treatment

A

common esp in girls, self-limiting. physic and rarely surgery.

anterior knee pain due to patellofemoral dysfunction (due to muscle imbalance, ligament laxity, subtle skeletal deposition)

112
Q

what is patellar instability?

A

dislocation and subluxation of patellar commonest in adolescents. related to trauma or predisposed by lax ligaments/bony abnormality.

113
Q

what complications might patellar dislocations cause?

A

osteochondral fracture with a fragment of hyaline cartilage with/without subcentral bone breaking off:
small fragments = remove and big = fix by surgery

recurrent dislocations can occur, stabilises with inc age and physio. recurrent dislocation may require surgery to reconstruct

114
Q

what is Osteochondritis dissecans (OCD)?

A

Osteochondritis where a fragment of hyaline cartilage and variable amounts of bone fragments break off the surface of the joint, the knee is commonest affected joint with medial femoral condyle most affected site.

115
Q

who does Osteochondritis dissecans occur in usually + PC?

A

adolescent but may occur later,

PC = poorly localised pain, effusion and occasionally locking

116
Q

investigating Osteochondritis dissecans

A

x-ray difficult to see,

MRI to diagnoses, bilateral (25%).

117
Q

complications of Osteochondritis dissecans

A

can result in loose bodies in knee joint or “pothole”; predisposes to OA.

fragment may be fixed or removed surgically

118
Q

meniscal tears background info

A

meniscal tears occur in kids/teens, younger have higher chance of healing with surgical meniscal repair.

119
Q

treating meniscal tears

A

NSAID, physio, bracing, corticosteoird IA

120
Q

meniscal problems

A

meniscal tears and discoid meniscus

121
Q

basic info for discoid meniscus

A

some children have abnormally-shaped (variant) discoid meniscus. [usually lateral meniscus]

circular rather than C-shaped can be asymptomatic or cause pain/popping. arthroscopic partial meniscectomy may help pain/popping.

122
Q

what are some paediatric foot and ankle problems?

A

talus Equinovarus, tarsal coalition, hallus valgus,

123
Q

what is talus Equinovarus?

A

clubfoot, 0.2% of births, 50% bilateral, abnormal alignment of joints between talus, calcaneus and navicular. >boys

124
Q

what occurs in talus Equinovarus?

A

plantar flexion, supination of forefoot and varus alignment of the forefoot, no immediate treatment.

125
Q

risk factors for talus Equinovarus

A

FHx, breech position,

126
Q

treatment of talus Equinovarus

A

eminently treatable with splint age and diagnosis obvious (early presentation).

extensive surgery and results less satisfactory (late presentation )

127
Q

what method is used to treat talus Equinovarus

A

Ponseti technique, commode ASAP, 5/6 weekly cast changes

80% require achilles tenotomy (minor procedure) for full correction.

then bracing in boots until 3/4years old to stop recurrence

128
Q

what is tarsal coalition?

A

abnormal bridge (bony, fiberous, cartilagenous) between calcaneus and navicular or calcaneus and talus.

129
Q

PC and treatment of tarsal coalition.

A

painful flat feet. symptoms may improve or require corrective surgery

130
Q

hallux valgus (bunion)

A

occurs in late adolescents and strong FHx.

surgical correction carries risk of recurrence in later life. usually NSAID, good footwear, orthotics, pain relief and rest = conservative treatment.

131
Q

what are some common paediatric/adolescent spine problems.

A

scoliosis and spondylolisthesis.

BACK PAIN IN CHILD ALWAYS A RED FLAG

132
Q

what are causes of back pain in children?

A

BACK PAIN IN CHILD ALWAYS A RED FLAG

infection (discitis). tumours (osteoid ostema) in children and spondylolisthesis may require prompt surgery

133
Q

define scoliosis

A

lateral curvature of the spine (also rotational deformity).

presents > female adolescents (child = more severe.)

134
Q

is scoliosis mainly idiopathic and what causes secondary scoliosis?

A

mostly idiopathic but can be secondary to neuromuscular disease, tumour, skeletal dysplasia or infection.

135
Q

what to do with painful scoliosis?

A

MRI urgently

136
Q

what to do with mild- non-progressive scoliosis? (majority)

A

doesn’t require surgery

137
Q

why would surgery be considered?

A

large unsightly curvature fixed for cosmetic aims

to improve wheelchair posture.

scoliosis causing restrictive lung disease

138
Q

what does surgery for scoliosis involve?

A

complex; requires vertebral fusions and long rods correcting the postural laments of the spine.

correcting larger curves carries risk of spinal cord injury.

139
Q

define spondylolisthesis

A

slipping of one vertebrae of another

140
Q

where does spondylolisthesis usually occur?

A

L4/L5 or L5/S1

141
Q

why does spondylolisthesis occur?

A

due to a developmental defect or a recurrent stress fracture of the posterior element which fails to heal

142
Q

risk factors for spondylolisthesis.

A

adolescent, inc body weight, sporty.

143
Q

PC of spondylolisthesis.

A

low back pain and radiculopathy (if severe).

may have paradoxial “flat back” due to muscle spasm and can have “waddling gait”

144
Q

what is radiculopathy?

A

Radiculopathy is a condition due to a compressed nerve in the spine that can cause pain, numbness, tingling, or weakness along the course of the nerve.

145
Q

treatment of spondylolisthesis.

A

minor slip - observe + rest/physio

severe slip - stabilisation + possible reduction (risks nerve injury)