Title: Neurological Disorders
1Neurological Disorders
- Sherry Burrell, RN, MSN
- Rutgers University
- Nursing III
2General Neuro Signs / Symptoms
- Fainting
- Dizziness
- Seizures
- Headache
- Memory Loss
- Weakness
- Pain
- Numbness / Tingling
- Speech changes
- Vision changes
- Tremors
- Paralysis
3Neurological History
- Explore presenting compliant(s)
- Precipitating events
- Progression of signs / symptoms
- Client Information
- Allergies
- Medical, surgical and / or traumatic history
- Medications
- Habits
- Lifestyle changes
- Family History
4Neurologic Assessment
- Physical Examination Components
- Level of consciousness
- Motor function
- Pupillary function / eye movements
- Respiratory pattern
- Vital signs changes
5Level of Consciousness
- Most important aspect of neurologic examination
- Level of consciousness first to deteriorate
(often subtle) - Consciousness
- Arousal (alertness) and Awareness (content)
- Levels of Consciousness
- Alert
- Lethargic
- Obtunded
- Stuporous
- Comatose
Thalen Box 24-2 pp. 647
6LOC Assessment Tools
- Glasgow Coma Scale (GCS)
- Three Categories
- Eye opening, verbal response and motor response
- Scoring
- Highest or best possible score 15
- A score of lt 7 indicates coma (generally)
- Lowest or worst possible score 3
- Not appropriate for use in
- Children, intoxicated clients or spinal cord
injuries
Thalen Table 24-1 pp.647
7Motor Assessment
- Steps of examination
- Observe for spontaneous movement
- Elicit motor movement in response to stimuli
- Type of Stimuli
- Verbal
- Simple and direct statements no visual or
tactile stimuli - Reduce environmental stimuli or distractions
- Noxious (painful)
- When no response to verbal stimuli
- Acceptable methods nail bed pressure and
trapezius pinch
8Motor Responses
- Level of Motor Movements Strength
- Evaluate each extremity compare with opposite
side and record separately - Other considerations Seizure activity
- Abnormal Motor Responses
- In the unconscious client noxious stimuli may
elicit abnormal posturing - Decorticate (abnormal flexion)
- Decerebrate (abnormal extension)
- Flaccidity
9Abnormal Posturing
? Decorticate Posturing
? Decerebrate Posturing
10Motor Reflexes
- Deep Tendon Reflexes (DTR)
- Tap appropriate tendon with percussion or reflex
hammer usually done by MD - Achilles (ankle), quadriceps (knee jerk), biceps
and triceps - Graded 0-4 ( 0 none? 2 normal ? 4
hyperactive) - Superficial Reflexes
- Corneal
- Gag
- Swallowing
- Oculocephalic (Dolls eyes)
- Abnormal Adult Reflexes
- Babinski
11Pupillary Function Eye Movement
- Evaluate both pupils for equality
- Size (mm)
- Shape
- Response to light note consensual response
- Extraocular movements (EOM)
- CN III, CN IV and CN VI
12Respiratory Alterations
- Cheyne-Stokes
- Rhythmic crescendo decrescendo rate and depth
of respiration brief periods of apnea - Central Neurogenic Hyperventilation
- Very deep, very rapid respirations no apnea
- Apneustic
- 2-3 second inspiratory and / or expiratory pause
- Cluster Breathing
- Groupings of irregular, gasping respirations
separated by long periods of apnea - Ataxic Respirations
- Irregular, random pattern deep and shallow
respirations with periods of apnea (irregular
too).
Thalen table 24-2 pp. 655
13Vital Sign Changes
- Cushings Triad
- Severe elevations in intracranial pressure result
in classic clinical manifestation of Cushings
Triad - Bradycardia
- Systolic hypertension (with widened pulse
pressure) - Bradypnea
- Grave occurrence, if increased ICP is not
addressed herniation will result.
14Diagnostics
- X-rays
- CT Scans
- MRI
- Cerebral angiography
- Evoked potentials
- Myelography
- Lumbar puncture
- Laboratory testing
- Serum, CSF, tissue biopsies and urine
15Intracranial Pressures (ICP)
- Brain contained within the skull (closed
container) - Intracranial space is occupied by three
components - Blood (arterial venous) 150 ml
- Cerebral Spinal Fluid (CSF) 150 ml
- Brain Tissue / Substance 1400 ml
- Normal physiologic conditions ICP lt 15 mmHg
- Increased ICP
- Any value sustained at 20 mmHg requires medical
intervention.
16 Increased Intracranial Pressures
- Monro-Kellie Hypothesis
- Increase in one intracranial component must be
compensated by a decrease in one or more of the
other components. - Closed container compensation is limited once
exhausted the result is a rapid increase in ICP - Causes of Increased ICP
- Trauma
- Head injuries (most common)
- Intracranial Tumors
- Space occupying lesions
- Other Causes
17Cerebral Perfusion Pressure
- Cerebral perfusion pressure (CPP) is the pressure
needed to ensure blood flow to the brain - CPP MAP- ICP
- The brain needs a cerebral perfusion pressure
(CPP) of 80-100mmHg. - Below 30 mmHg (sustained) irreversible neurologic
damage occurs. - If CPP equals to SBP cerebral blood flow will
cease.
18Increased ICP
- A pathologic condition altering the relationship
between intracranial volume and pressure. - Leading to
- Decrease in cerebral blood flow and tissue
perfusion - Stimulation of cerebral swelling (edema)
- Shifts in brain tissue (herniation)
19Stages of Increased ICP
- Stage I
- Headache
- History of head injury
- Vital signs / pupillary responses normal
- Stage II
- Mental Status Changes (first change)
- Vital signs / pupillary responses normal
Thalen figure 24-7 pp.657
20Increased ICP
- Stage III
- Decreased LOC (lethargy ?obtunded ?stupor)
- Vomiting (maybe projectile)
- Small pupils sluggish responses to light
- Cushings Triad systolic HTN (widening pulse
pressure), bradypnea and bradycardia (bounding,
slow pulse) - Stage IV
- Comatose
- Pupils dilated ? fixed
- Abnormal posturing decorticate / decerebrate?
flaccidity - Cushings triad progresses ?herniation ? brain
death
21ICP Monitoring
- Four Methods of ICP Monitoring
- Intraventricular
- A small catheter is placed within the ventricular
system (ventriculostomy) - Subarachnoid
- Hollow bolt or screw into the subarachnoid space
- Epidural
- Small fiberoptic sensor into epidural space
(between skull dura) - Intraparechymal
- Small fiberoptic catheter into the white matter
of brain tissue (parenchyma)
22Management of Increased ICP
- Nursing Activities and Positioning
- HOB elevated to 30 degrees
- Trendelenburg, prone positions should be avoided
/ limited - Head should be maintained neutral position
(midline) - Avoid extreme neck flexion or rotation and hip
flexion - Identify daily care activities that increase ICP
- Avoid Valsalva maneuver turning or straining
with BM - Provide rest periods
- Reduce environmental stimuli
- Encourage significant other contact and
therapeutic touch
23Management of Increased ICP
- Nursing Activities and Positioning Cont.,
- Respiratory / Ventilator Considerations
- Suctioning
- Hyperoxygenate before and after each pass
- Limit the number of passes (1 to 2) and duration
(lt 10 seconds) - Ensure tracheostomy ties are not too tight
- Limit / avoid coughing
- Avoid PEEP gt 20 cm H2O
- Hyperventilation
- PaCO2 low end of normal current trend ( 35 mmHg)
24Management of Increased ICP
- Nursing Activities and Positioning Cont.,
- Prevention Infection
- Aseptic techniques ICP catheter, other invasive
lines and foley - Temperature Regulation
- Hyperthermia antipyretics and cooling blankets
- Blood Pressure Control
- Delicate balance in neurologic patient
- Sedatives used first then antihypertensives
- Seizure Control
- Anticonvulsants Prophylactic
- i.e. Dilantin until therapeutic levels reached
Ativan - Seizure Precautions
25Management of Increased ICP
- Nursing Activities and Positioning Cont.,
- Volume Control
- CSF Drainage (ventriculostomy)
- Osmotic Diuretics
- Control of Metabolic Demand
- Barbiturate Therapy / Coma
- Control of Cerebral Edema
- Steroids (i.e. dexamethasone)
- Nutrition Support
- High protein
- Parenteral nutrition
- Pain / Anxiety Management
- Benzodiazepines to clam without decreasing LOC
26Management of Increased ICP
- Nursing Activities and Positioning Cont.,
- Monitoring Considerations
- Vital Signs
- Neurological exams
- Trends of signs and symptoms paramount
- ICP monitoring device
- Note amount and appearance of CSF drainage
- Strict I O
- Daily weights
- Laboratory values
27Management of IICP
- Surgical Considerations
- Craniotomy
- Removal of tumor, relieve increased ICP, evacuate
a hematoma and /or control hemorrhage. - Surgical Approaches
- Transcranial
- Transsphenoidal
28Craniotomy Considerations
- Pre-operative Nursing Care
- Baseline assessment data
- Laboratory data sent and monitored
- Diagnostics completed
- Prep surgical site (shave hair)
- Support
- Education
- Post-operative Nursing Care
- Neurological checks hourly or more!
- Vital signs hourly
- Maintain ICP monitoring device
29Post Craniotomy
- Nursing Prevention / Management
- Increased ICP
- i.e. vomiting
- Hemorrhage
- Fluid and electrolyte imbalance (check labs.)
- CSF leak
- Deep vein thrombosis (DTV) prevention
- Gastric ulcerations
- Pulmonary infections
- Seizures
- Air embolism
30Complications of Increased ICP
- Diabetes Insipidus
- SIADH
- Herniation
- Brain Death
31Diabetes Insipidus
- Decreased secretion of antidiuretic hormone (ADH)
- Clinical Manifestations
- Hypernatremia (serum)
- Excessive water losses via urine (very dilute
urine) - Client may become hypovolemic or dehydrated
- Management
- Fluid volume
- Encourage oral intake of fluids (if possible)
- I.V. fluids careful monitoring laboratory
results and BP - Electrolyte replacements
- Vasopressin therapy
- Pitressin or Desmopression DDAVP
32SIADH
- Increased secretion of antidiuretic hormone (ADH)
- Clinical Manifestations
- Decreased urinary output (very concentrated
urine) - Hyponatremia (serum)
- Further increase in ICP
- Volume overload
- i.e. peripheral edema and weight gain
- Management
- Fluid restriction
33Herniation Brain Death
- Herniation
- Result of excessive ICP result cessation of CBF
- Leads to irreversible brain anoxia and brain
death - Brain Death
- Complete, irreversible cessation of function of
the entire brain and brain stem. - Mechanical support sustaining life
- Nursing Considerations
- Organ Donation
34Head Injuries
- Broad term to classify sudden trauma to head
including injuries sustained to the scalp, skull
or brain. - Most common causes
- MVA motor vehicle accidents (50)
- Falls (21)
- Violence (12)
- Sports related-injuries (10)
35Mechanisms of Head Injuries
- Closed Injuries
- Blunt, Nonmissile Injuries
- Coup and Contrecoup
- Direct injury at site of initial impact of trauma
(Coup) - Indirect injury at opposite pole (Contrecoup)
- Open Injuries
- Penetrating, missile injuries
- Communication of intracranial contents with
external environment - Increase risk of infection
36Clinical Manifestations
- Neurological deficits
- Altered LOC
- Confusion
- Vital sign changes
- Altered reflexes
- Gag
- Corneal
- Headache
- Dizziness
- Impaired hearing or vision
- Sensory or motor dysfunction
- Seizures
37Scalp Injuries
- Isolated scalp injuries usually classified as
minor head injuries. - The scalp is highly vascular with poor
constrictive abilities bleeding is often profuse - Infection is a major concern, which must be
prevented!!
38Skull Fractures
- Actual break in continuity of skull
- Cause is extreme, forceful trauma
- Brain injury may or may not occur
- Types of Skull Fractures
- Linear
- Basilar
- Depressed
39Skull Fractures Cont.,
- Basilar
- Fracture at base of skull usually temporal or
frontal areas - Bleeding from nose, pharynx, ears or into
conjunctiva - Bruising
- Battles sign ecchymosis over mastoid
- Raccoon (eyes) sign bilateral periorbital
ecchymosis - CSF leak from nose or ears
- Watch for Infection !!
- Depressed
- Downward depression of bone into intracranial
cavity - Maybe comminuted shattering or fragmenting of
bone
40Cerebral Concussion
- Head injury with temporary loss of neurological
function with no (gross or microscopic)
structural damage. - Cause jarring of the brain closed (nonmissile)
injuries - Clinical Manifestations
- Loss of consciousness usually brief
- S/Sx Dependent on location of injury to brain
tissue - Post concussion syndrome
- Usually occurs within 24 to 48 hours after injury
but, may present up to several months later. - S/Sx HA, dizziness, lethargy, irritability and
anxiety - May affect everyday home or work-related
activities
41Cerebral Contusion
- More severe injury than concussion
- Bruising of the brain
- Maybe caused by both open and closed injuries
- Initial loss of consciousness
- Clinical Manifestations
- Alterations in level of consciousness
- Focal neurological deficits
- Seizures
- Vomiting (maybe projectile)
- Increased ICP
42Intracranial Hemorrhage (ICH)
- Trauma can cause bleeding within the brain tissue
or within the spaces surrounding the brain - The result is hematomas or collections of blood
within cranial vault most serious of brain
injuries - Classified according to location
- Epidural hematoma
- Subdural hematoma
- Intracerebral hematoma
43Epidural Hematoma
- Blood collects between skull and dura mater
- Most often arise from arterial hemorrhage
- Cause usually is injury of middle meningeal
artery in the temporal region - Clinical Manifestations
- LOC after initial trauma (immediate at site of
injury) - Lucid interval
- Rapid deterioration in neurologic respiratory
function - Medical Emergency rapid surgical intervention
44Subdural Hematoma
- Blood collects between dura arachnoid maters
- Often venous in origin
- Cause is usually injury to bridging veins
- Associated with coup / contrecoup injuries
- Can occur
- Acute (less than 48 hours after injury)
- Subacute (48 hours- 2 weeks)
- Chronic (over 2 weeks)
45Subdural Hematoma Cont.,
- Acute Subdural hematoma
- Loss of consciousness
- Pupil sluggish ? dilatation and becomes fixed
- Requires rapid surgical intervention
- Subacute Subdural Hematoma
- May or may not have loss of consciousness
- Chronic Subdural Hematoma
- Often forget actual injury common in elderly
- S/Sx fluctuate or come and go
- Severe headache personality changes mental
deterioration and focal neurologic deficits
46Intracerebral Hematoma
- Blood collects within the cerebral tissue
(parenchyma) - Most common with open (missile) injuries
- Result in increased ICP secondary to bleed which
is accompanied by cerebral edema displacing
tissue from within the brain structure - Other S/Sx Specific to location and size of
bleed - Small bleeds can cause changes in neurologic
status - Deterioration is often sudden surgical and
medical interventions.
47Head Injury Considerations
- Management
- Frequent neurologic assessments / vital signs
- I O and daily weights
- Increased ICP
- Fluid and electrolyte balances
- Pharmacologic
- Positioning
- Nursing Activities
- Maintain skin integrity
- Protection from injury
- Prevent infection / provide rest
48Brain Tumors
- Space-occupying intracranial lesions
- Benign or malignant.
- Clinical manifestations differ according to area
of lesion and rate of growth - Common Signs / Symptoms
- Alterations in consciousness
- Decreased neurologic functioning
- Headaches
- Seizures
- Vomiting (maybe sudden and projectile)
49Types of Brain Tumors
- Brain tumors within the brain tissue
- Gliomas Most common type of brain tumor
- Astrocytomas
- Most common type of Glioma
- Slow growing malignant
- Invasive (difficult to surgically remove entire
tumor) - Glioblastomas Mulitforme
- Is a advanced stage of Astrocytomas
- Rapid growing malignant invasive
- Poorest prognosis
50Types of Brain Tumors Cont.,
- Brain tumors arising from supporting structures
- Meningiomas
- Encapsulated, non-invasive usually benign
- Slow growing well defined
- Compresses rather than invades
- Acoustic Neuromas
- Non- malignant slow growing
- CN VIII affected HA, tinnitus, hearing loss,
impaired balance, unsteady gait facial pain /
numbness on the side of tumor - Developmental Tumors
- Angiomas
- A benign mass of abnormal blood vessels with thin
walls prone to rupture
51Brain Tumor Considerations
- Management
- Increased ICP
- Corticosteroids (dexamethasone and prednisone)
- H2 blocker must accompany
- Osmotic Diuretics
- Anti-seizure medications
- Tumor removal / destruction
- Craniotomy
- ICP monitoring
- Radiation
- Chemotherapy
- Small role poor penetration of blood-brain
barrier
52Spinal Cord Injury (SCI)
- In the United States
- 10,000 spinal cord injuries occur annually.
- 200,000 people live with disabilities from spinal
cord injuries. - Most prevalent between the ages of 16 and 30
years of age. - Higher incidents in
- Males vs. Females
- African American vs. Caucasians
- Most prevalent causes of traumatic spinal cord
injuries - MVA (35)
- Violence (30)
- Falls (19)
- Sports-related injuries (8)
53Spinal Cord Injuries
- Spinal cord itself ends at L2 but, the vertebral
column continues to the coccyx. - Most often occur in areas of the spinal cord that
have the greatest range of mobility - Cervical 5th-7th
- Thoracic 12th
- Lumbar 1st
54Pathophysiology
- Primary Injury
- Spinal cord damage occurring at the moment of
impact. - Secondary Injury
- Spinal cord damage occurring as a result of
ongoing cellular change from edema, ischemia and
hemorrhage. - Can continue for weeks after the initial impact.
55Classification of SCI
- Complete Injuries
- Loss of voluntary motor activity and sensation
below the level of injury - Quadriplegia (C1 T1)
- Paraplegia (T2-L1)
- Incomplete Injuries
- Variable or mixed losses of voluntary activity
motor and sensation below the level of injury. - Anterior Cord Syndrome
- Posterior Cord Syndrome
- Brown-Sequard Syndrome
- Central Cord Syndrome
(SB Chart 63-8 pp. 1928)
56Acute Spinal Cord Injuries
- Pharmacologic Management
- High-dose corticosteroids Methylpredinsolone
- H2 Blocker prevent gastric ulcerations
- Medical Management
- Cervical Fractures
- Fixed Skeletal Fracture Traction
- Realign the vertebrae, facilitate bone healing
prevent further injury. - Halo Device
- Cervical spine immobilization allows for
ambulation self care - Thoracic Lumbar Fractures
- Body cast (plastic or fiberglass)
- Immobilization of thoracic lumber spine
bedrest supine position
57Surgical Management
- Laminectomy
- Removal of a portion of the vertebral ring called
the lamina - Allowing for expansion from edema or for removal
of boney fragments / disk material. - Spinal Fusion
- Fusion of vertebral bodies to prevent movement
and increase stability of the spinal column. - Spinal Rodding
- Use of metal rods stabilize and realign the
spine. - Nursing Surgical Considerations
- Post Operative Braces
58Acute Complications in SCI
- Spinal Shock
- Autonomic Dysreflexia
- Deep Vein Thrombosis
59Spinal Shock
- A state of shock occurring shortly after injury
to the spinal cord injury may last for up to a
month. - Occurs most often with a spinal cord injury at T6
or above - A sudden loss of reflexes, sensory, motor and
autonomic nervous system activity below the level
of spinal cord injury.
60Spinal Shock Cont.,
- Clinical Manifestations
- Hypotension
- Bradycardia
- Loss of bladder tone urinary retention
- Loss of bowel tone paralytic ileus
- Nursing Considerations
- Frequent monitoring
- Blood pressure support care with repositioning
- Bowel and bladder support
- Return of spinal reflexes indicate the resolution
of spinal shock.
61Autonomic Dysreflexia
- A life threatening condition that occurs with
SCI. - It generally occurs after spinal shock has
resolved and spinal reflexes return but, may
persist throughout lifespan. - The cause is a massive sympathetic response to
noxious stimuli. - Noxious stimuli often includes
- Distended bladder (most common)
- Bowel constipation or impaction
- Other pressure ulcers or cold drafts
- Usually occurs with SCI at T6 or above
62Autonomic Dysreflexia Cont.,
- Clinical Manifestations
- Hypertension (sudden)
- Bradycardia
- Serve, pounding headache
- Facial flushing
- Nasal congestion
- Chills and fever
- Nausea
- Profuse sweating
63Autonomic Dysreflexia Cont.,
- Nursing Management
- Identify and remove noxious stimuli if possible
- Bladder
- Bowel
- Skin or cold drafts
- Loosen constrictive clothing or devices
- Raise the head of the bed or sit the client up
- Other Considerations
- Antihypertensive Medications
- Maintain appropriate room temperature
64Deep Vein Thrombosis (DVT)
- High risk due to immobility
- Nursing Assessment
- Inspect both lower extremities for redness or
localized swelling - Measuring calf circumference (compare
bilaterally) - Collaborative Prevention
- Pharmacologic Low-dose Heparin or Lovenox
- Elastic compression stockings
- Compression boots
- Encourage fluid intake
- ROM exercises
- Prevention is essential a DTV can lead to a
pulmonary embolism
65Acute Assessment in SCI
- ABCs
- Immobilize head, neck and spine!!
- Neurologic examination
- Motor
- Reflexes
- Sensory
- Dermatomes (Thalen pp. 641 figure 23-26)
66Nursing Management
- The complete spinal cord injured client
- Goal of nursing management
- Attain some form of mobility
- Maintain skin integrity
- Bladder and bowel management
- Address psychosocial needs
- Preserve sexual function
- Prevention complications
67Nursing Considerations
- Respiratory Status
- Ventilator care if necessary
- Administer supplemental oxygen as needed
- Assist in clearing bronchial secretions
- Suctioning hyperoxygenate
- Chest PT
- Add humidity to supplement oxygen
- Encourage liquids
- Cough assistance (Quad coughing)
- Monitor Frequently
- Prevent Infection
68Nursing Considerations Cont.,
- Immobility
- Proper body alignment and transfer of client
- Repositioning every two hours turn clock
- Prevent pressure ulcers
- Wheelchair weight shifts /cushions
- Passive ROM 4-5x day begin as soon as possible
- Maintain joint mobility prevent contractures
- Reduce spasticity (meds help i.e. Baclofen)
- Encourage mobility as soon as possible
- Wheelchair Manual or electronic (oral / thumb
controlled)
69Nursing Considerations Cont.,
- Pressure Ulcers
- The spinal cord injured client can develop
pressure ulcers rapidly. - Turn, turn, turn every two hours !!
- Locations common to assess
- Ischial tuberosity
- Greater trochanter
- Sacrum
- Heels
- Always check under braces and other devices for
skin integrity keep skin dry
70Nursing Considerations Cont.,
- Skin Integrity
- Assessment of skin with every position change
- Meticulous skin assessments
- Observe for any redness or skin breakdown break
down - Frequent turning !!
- Common causes of alterations
- Immobility
- Wheelchair trauma
- Urinary or bowel incontinence
71Nursing Considerations Cont.,
- Neurogenic Bladder
- Two main types seen with spinal cord injuries
- Reflex or Spastic Bladder
- Most common with complete cord injuries
- Loss of the sensation to void, bladder fills and
empties automatically it may or may not be
completely empty. - Non-reflexive or Flaccid Bladder
- Bladder fills and becomes greatly distended which
results in overflow incontinence - Bladder unable to contract and no discomfort
associated with fullness overstretching of
bladder and detrusor muscle may lead to reflux
72Nursing Considerations Cont.,
- Neurogenic Bladder Cont.,
- Adhere to client normal bladder program
- Often established by frequent reflex stimulation
or intermittent catheterization - Client or Caregiver Education
- Intermittent / straight catheterization
- Record fluid intake
- Voiding patterns
- Signs and symptoms of UTI autonomic dysreflexia
- Urinary Diversion Procedures
73Nursing Considerations Cont.,
- Bowel Elimination
- Diet
- High in fiber encourage fluids
- Bowel program
- Every 48 hours after meals (same time) Proper
positioning - Reflex stimulation / manual removal of stool
- Stool softeners or laxatives enemas only when
necessary - Teach signs and symptoms of impaction
- Contractures
- Splints / passive ROM
74Nursing Considerations Cont.,
- Reproductive / Sexual Function
- Women with spinal cord injuries can become
pregnant but, face life-threatening complications - Men with spinal cord injuries prosthetic penile
implants Viagra - Climax may or may not be achieved
- Psychosocial
- Coping with disability important to set
short-term realistic goals - Coping with lifestyle, role and financial changes
- Depression
- Support groups, social work
- Allow to express concerns, fears and frustration
75Chronic SCI Complications
- Autonomic dysreflexia
- Bladder and kidney infections
- Spasticity
- Contractures
- Pressure ulcers
- Can lead to sepsis and osteomyelitis
- Depression
- Bone and joint disorders