PBL 3: Fractures & dislocations Flashcards
Discuss the basic epidemiology, presentation, investigation, management, complications and prognosis of fractures
Types of fracture Causes:
Traumatic: Most common and where a major force is exerted that breaks the bone eg falling onto your arm.
Pathological: Where the bone is inherently weak and breaks with seemingly little force, eg in osteoporosis or if there is a bone cyst.
Stress: Occur after repeated mild trauma eg a tibia stress fracture in runners.
Types of fractures:
Transverse: a split horizontally across the bone usually when a force is exerted directly on the bone. The healing time is long as there is not much surface area for the bone to attach back together
Spiral fractures: this is usually where the distal part of the limb is stationary and the weight of the body twists around it. It can heal twice as fast as a transverse fracture as there is a lot more surface area for the two pieces of bone to reattach.
Oblique fractures: Fractures that are usually caused by rotational and a strong blow to the bone, these look similar to rotation but the break pattern is more of a diagonal line than a spiral.These also heal quickly.
A butterfly fracture is similar to an oblique and spiral fracture in its cause but there is also a fragment of bone that has broken off. Healing is usually slow.
A comminuted fracture is where enormous force has shattered the bone into pieces causing extensive damage
Two break classifications:
Compound means the skin has been broken due to the break. Tibial fractures are the most common type of compound fracture.
Closed means the skin has remained intact around the break.
When someone comes in with a suspected broken bone two x rays are taken at perpendicular angles.
Initial management of fractures:
Stop any external bleeding
Immobilise the bone
Arrange for tests
Stabilisation: different ways to stabilise a fracture are:
Cast
Sling
Brace
Splint
Reduction:If the bones are displaced the bones need to be returned to heal properly which is called reduction. This is either open or closed. If the fracture is intra articular this usually requires open reduction to give the joint the best possible chance.
Wires or pins can be put in to hold the bones in place to heal
Following reduction blood vessels and nerve function need to be checked to make sure there’s no damage or pressure to them.
Complications:
Compartment syndrome is where due to swelling, the blood supply to muscle in a closed compartment of connective tissue is cute off and the muscle can become ischaemic. This can be limb threatening and is a medical emergency.
Symptoms are more pain than usual no pulse and paraesthesia
Fat embolus:
After long bone fractures that are severe if the bone marrow comes into contact with a vein or artery fat from bone marrow can enter the vessel and get trapped in the lungs blocking blood flow.
Symptoms are shortness of breath and sometimes confusion from low O2 levels.
Osteoarthritis can occur after intraarticular fractures
Growth plate damage can occur in children which can stop growth.
Hip fractures: (relating to case)
Most commonly caused by a fall fro standing height
Can be divided into
Intracapsular and Extracapsular
The blood supply for the femoral head comes from outside the capsule from the medial femoral artery.
If there is an intracapsular fracture and it is displaced, it can sever the blood supply to the femoral head, meaning it can never recover and needs to be removed. This is usually treated by adding an artificial femur head or if the patient is young or active sometimes a full hip replacement for better mobility. If the bone is not displaced, there is still a chance for the artery to not be compromised
In an extracapsular fracture the blood supply to the bone is not usually compromised so the bone has a chance to heal properly
It can usually be treated with a dynamic hip screw or intramedullary nail
Describe the radiological principles behind diagnosing and describing fractures
· Classification of fractures helps us work out how they occurred and can provide optimal treatment.
· Important to heal the bone and soft tissue
· Majority of fractures are diagnosed using history and imaging.
Radiography
· Scans give us an accurate assessment and classification of the extent of the injury (i.e. transverse, spiral, commuted, oblique).
· Clarifies how the injury happened and confirms diagnoses.
· Soft tissue swelling can be seen, displacement of nearby soft tissue is a secondary sign of fracture.
· Serious chest injuries could be present without any sign of external injuries.
· Early imaging is required to see these injuries. Less than 10% require surgery, however, early recognition can reduce mortality.
· X-rays can be used in the rehabilitation process to show fracture healing and help determine when casts can be removed.
· You will receive at least 2 radiographs taken 90 ° from each other, lateral and antero-posterior.
· Fractures can be difficult to see in the elderly and osteoporotic due to changes to the bone structure which can be interpreted as fractures.
· Low radiation must be used for children, so it doesn’t harm their tissues
· Children’s bones look different because they are still growing. Important to make sure growth plates aren’t damaged
Don’t X-ray:
· Ribs: X-rays do not change patients’ management.
· Nasal bones
· Coccyx: shapes vary, and fracture can be difficult to spot, but doesn’t affect diagnosis
· Chest x-rays are done in trauma if patients have shortness of breath, pleuritic chest pain or reduced breath sounds to exclude a pneumothorax.
Signs of a fracture:
Bone:
· Lucent lines
· Sclerotic lines
· Cortical breach
· Disturbance of trabeculae
· Change in bony contour
Supplementary:
· Hemarthrosis
· Lipohaemarthosis
· Soft tissue swelling
Classification of fractures:
· Spiral: twisting force, long fracture line.
· Oblique: twisting force, short fracture line.
· Transverse: bending force, often with a third fragment called bending wedge.
· Vertical: along the shaft, rare.
· Comminuted: high energy force with lots of fragments.
· Closed: skin is not broken, no wound.
· Open: skin is torn, high risk of infection.
Positioning of fractures:
· Distracted: far apart
· Impacted: close together
· Laterally/medially displaced
Discuss the basic epidemiology, presentation, investigation and management of compartment syndrome.
Overview
Compartment refers to separate sections of the body that contains muscles, nerves, blood vessels surrounded by a layer of fibrous connective tissue called fascia (the muscles of the leg below the knee and in the forearm lie within rigid fascia)
Compartment syndrome is when the pressure inside the fascia increases, results in the reduction of blood supply and results in tissue necrosis
Typically occurs in the limbs, usually in the lower leg or the forearm, after traumas like a bone fracture
If not treated in time leads to permanent muscle and nerve damage
Presentation of Compartment Syndrome
Signs and Symptoms:
Pain: sharp and deep, worsens with passive stretching of affected muscles
Paraesthesia: tingling and numbness
Pulselessness: only occurs when the compartment pressure is so high that arteries collapse
Pallor and Poikilothermia: pale skin and inability to regulate body temperature and usually presents as cold extremities
Paralysis: rare and suggests extensive damage to muscles and nerves
Causes:
Most common cause of compartment syndrome is bleeding inside the compartment
Typically occurs with:
Long Bone Fractures: tibia or the forearm bones
Penetrating Wounds
Surgical Procedures: blood vessel injury
Swelling of the Tissue: after severe burns, intravenous drug injections, repetitive use of the injured muscles, or a vigorous muscle contraction (tetany, seizures)
Limb Compression: crash injury, inappropriately placed cast
Reperfusion Injury: occurs with the reestablishment of blood flow to hypoxic cells (These cells stop producing antioxidants, so providing them with oxygen again can lead to formation of toxic reactive oxygen species that you cannot get rid of)
Investigation of Compartment Syndrome
Diagnosis:
Physical Examination: affected groups of muscles appear stiff, firm and hard; individual complains of pain that worsens with passive stretching of the muscles
Diagnostic Tool: intracompartmental pressure monitors that can be inserted directly inside the compartment
Blood Test: when rhabdomyolysis develops, a blood test would show increased levels of creatine kinase and myoglobin
Urinalysis: if the urine is tea coloured, suggests increased levels of myoglobin
Imaging Techniques (Radiography, CT, MRI and Ultrasound): can help locate bone, muscle and blood vessel injuries
Management of Compartment Syndrome
Treatment is normally surgical, and involves a procedure called fasciotomy:
Fascia is cut open with a longitudinal incision, relieving the pressure and re-establishing normal blood flow (any necrotic muscle should be excised)
Wound is left open for a few days until the cause of increased pressure is treated (if the swelling does not resolve over the first few days, skin grafting may be needed)
The treatment is to release the compartment fascia and to correct any underlying cause if possible
When compartment syndrome is caused by some external factors like an inappropriate cast, its removal can result in spontaneous recovery and surgery may not be needed
Untreated compartment syndrome has serious consequences, so it is reasonable to proceed to fasciotomy on clinical suspicion alone
Describe the common joint dislocations and their complications and management
Joint dislocations a complete separation of 2 articulating bony surfaces.
Most common sites include the shoulder, finger, patella, elbow and hip
Shoulder
dislocation can be anterior/ posterior
Anterior dislocation is most common + inferior is uncommon
Causes → Force from fall/blow
Risk Factors → previous dislocations, sports
Complications → nerve damage (brachial plexus + axillary neve) from injury/ performing reduction
Diagnosis → view, X-Ray ( anteroposterior view and lateral view)
Treatment → Reduction (put back in place) and immobilisation(placed in a sling). X-Ray taken to confirm reduction and to ensure that fractures haven’t occured.
Strengthening exercises should be advised
Can do most activities after 2 weeks
Hip
Try to reduce within 6 hours from injury prevents avascular necrosis (surrounding tissue dies due to a lack of oxygen caused by blocked artery)
Simple → Dislocation without fracture
Complex → Dislocation with fracture of acetabulum or proximal femur
Can be posterior (90%) or anterior
Risk → women> men, older age,
Causes → mostly trauma (esp. in young people), after hip replacement surgery
Complications → damage to surrounding muscles and tendons, damage to sciatic nerve (posterior), fractures on femur head / acetabulum,
Diagnosis → observations, X-Rays (confirms dislocation and successful relocation), CT and MRI (to see further damage and more complicated fractures)
Treatment→ Brace/splint/harness, surgery, relocation
Rehab - 2-3 months recovery minimum
Knee Dislocation
Complication
Acute compartment syndrome
Peroneal nerve injury
Injury to popliteal artery and vein
Management
Some are not reducible, so open reduction needed (surgical)
Elbow
Closed reduction then immobilise
can cause disruption to the brachial artery
All dislocation complications include:
tearing muscles, ligaments and tendons, and nerves being pinched
Discuss the methods of imaging bone and the advantages and disadvantages of each
X-Ray
· most common diagnostic technique used to image bones.
· Electromagnetic waves (radiation) are sent through the body in order to capture a single image of internal structures
· 2 images are taken
· Soft tissue allows more radiation to pass through
Pros:
· Fast
· Cheap
· Useful in trauma
· Images stored on computer
· Easy diagnosis
Cons:
· Only 2D image
· Doesn’t show soft tissue injuries
· Can be damaging to body
CT Scan
· Computerised 360˚ scan which produces a digital image of any cross section through the body.
· Constructs a 3D image of the body
· Distinguishes between different types of soft tissue - uses lots of rotating x-rays (around 500)
Pros:
· Produces images with excellent bony detail
· Higher general image resolution as compared to x-rays
· Can be subjected to multiplanar reformatting
· Differentiates between hard and soft tissue
Cons:
· Delivers a very high dose of radiation - equivalent to 500 x-rays
· Not suitable for all patients, ie if pregnant or sensitive to the contrast agents
· More expensive
· Less readily available
MRI:
· Uses strong magnetic fields and radio waves to produce detailed images of the internal structures - can be 2D or 3D
· One of the two magnets align the protons in the molecules to face new directions and gets realigned when switched off.
· Radiofrequency current is then pulsed through the patient, and it stimulates the protons.
· This makes it spin out of equilibrium, straining against the pull of the magnetic field
· The sensors detect the energy released.
Pros
· MRI can differentiate between white matter and grey matter
· Produces a very high-resolution image
· Free of ionising radiation
· Excellent soft tissue differentiation and good visualisation of vascular structures
Cons:
· Loud noises patients may require ear protection
· Nerve stimulation can happen from rapid switch fields from MRI
· Claustrophobic
· Longer to get results-more time consuming
· Limited availability and costly
Describe normal bone growth, normal fracture healing, abnormal healing and the common bone-cartilage tumours
· Function of bone: mechanical support, transmits force generated by muscles, protects the viscera (organs of the central cavity => chest, abdomen, pelvis), mineral homeostasis (bones can absorb minerals if mineral levels get too high), provides niche (comfortable environment) for red blood cells
Normal Bone Growth:
· Bones began to grow in the embryo in the 6th or 7th week of gestation
· Form either through intramembranous ossification (bone develops directly within mesenchymal/immature connective tissue sheets) or endochondral ossification (bone develops from a pre-existing cartilage model)
· Flat bones of face, most of skull bones and clavicle (collar bone) is formed via intramembranous ossification – skull and clavicle not fully ossified at birth so they can pass through birth canal as the bones can deform
· Flat bones of face reach adult size at the end of adolescent growth-spurt
· Intramembranous starts from foetal development to adulthood
· Base of skull and long bones formed through endochondral ossification – process takes longer
Fractures:
· Defined loss of bone integrity (bone density + ability to function) caused by a mechanical injury and/or a decrease in bone strength
· Most common pathologic condition that affects the bones
· Fracture types:
o Simple = Overlying skin is still intact
o Compound = Bone communicates with skin surface
o Comminuted = Bone is fragmented
o Displaced = Ends of bones at fracture site are not aligned
o Stress = Period of increased physical activity causes slowly developing fracture to worsen
o Greenstick = Extends partially through bone (common in infants when they have soft bones)
o Pathologic = Bone weakened by underlying disease (e.g., tumour)
Normal Fracture Healing:
- Rupture of blood vessels causes there to be a haematoma (blood clot) which fills in the gap created by fracture
- Haematoma provides fibrin mesh which is used to seal the fracture site and creates a scaffold for the inflammatory cells, fibroblasts (cell used for formation of connective tissue) and support for new capillary growth
- Inflammatory cells and degranulating platelets release platelet derived growth factors (PDGF), transforming growth factor–β (TGF–β), fibroblast growth factor (FGF) and other factors needed to activate osteoprogenitor cells in the periosteum, medullary cavity, and surrounding tissue to stimulate osteoblastic (osteoblasts produce osteoid which is rich in Type I collagen) and osteoclastic activity
- By end of first week, there is anchorage between the opposite ends of the fracture bones provided by a large amount of uncalcified tissue (soft callus/procallus)
- After around 2 weeks, soft callus becomes bony callus
- Woven bone is then deposited by the osteoprogenitor cells
- Sometimes, the activated mesenchymal cells in soft tissue and bone, around the fracture line, can differentiate into chondrocytes to make fibrocartilage and hyaline cartilage
- Along the fracture line, the newly formed cartilage undergoes endochondral ossification to create a network of bone with a new bone trabeculae in the medulla and beneath the periosteum so the fractured ends are now bridged together
- The callus continues to mature and faces weight-bearing forces which causes parts of it to be resorbed (absorbed again) and the remodelling reduces the callus size until the shape and outline of the fractured bone is reformed as a lamellar bone (contains parallel spirally arranged collagen fibres)
- Healing complete once medullary cavity (hollow part of bone that contains bone marrow) is restored
Abnormal Fracture Healing:
· Whilst a fracture is healing, it is easy for there to be a block or delayed
· Comminuted and displaced fractures often result in some sort of deformity
· Lack of healing due to:
o Inadequate immobilisation
o Extensive trauma to tissue
o Osteonecrosis (Avascular necrosis) – poor blood supply at fracture site
o Bone loss or weakened by radiation, tumour, or metabolic bone disease
o Space/tissue between fragments
o Infection (can be seen in compound fractures)
o Fractures involving joints as synovial fluid contains fibrinolytic agents that prevents haematoma formation
o Older age – poorer nutrition
o Drugs – steroid called corticosteroids impair fracture healing
Common Bone-Cartilage Tumours:
· Osteochondroma (clinically known as exostosis)
o Benign cartilage-capped tumour attached to underlying skeleton by bony stalk
o About 85% solitary – usually first diagnosed in late adolescence/early adulthood
o Rest of 15% is multiple hereditary exostoses syndrome – occurs during childhood
· Chondroma
o Benign tumours of hyaline cartilage that usually occur in endochondral bones
o Arise within medullary cavity or on cortical surface
o Usually diagnosed in individuals between the ages of 20 to 50
· Chondrosarcoma
o Malignant tumours that produce cartilage
o Subclassified into convention (hyaline cartilage-producing), dedifferentiated, clear cell and mesenchymal types – 90% are conventional type
o Men are twice as likely to be affected compared to women
Describe the medico-legal position concerning consent in adults and in children, in both emergency and non-emergency situations and how mental capacity may affect this
What is consent and why is it required?
Definition: permission for something to happen or agreement to do something.
Fundamental part of doctor patient relationship.
Trust honesty and integrity.
Patient autonomy and bodily integrity: without valid consent it counts as assault.
What makes consent valid?
Voluntary:
· Patient must be free to agree to or to refuse treatment
· Consent should be obtained without coercion or duress
Informed:
· The procedure must be explained in simple language
· Complications and ‘material risks’ should be discussed
· Any research on the condition should be discussed
Capacity:
· Must be able to understand the relevant information provided
· Be able to retain the information
· Be able to weigh up the pros and cons of the treatment proposed
· Be able to communicate their decision
What forms of consent are there?
Implied
· The patient presenting to clinic to be examined
· The arm offered for venepuncture
Oral
· Verbal conversation gaining permission
· Often formalised after the encounter with documentation and notes
Written
· Pre-emptive
· Involved
· Best supported in law
GMC guidelines state which procedures require written consent.
Without Capacity:
· Understand – retain – weigh up – communicate
· How do we assess capacity?
· 2 stage test of capacity (MCA 2005)
· 1) Does the person have an impairment of their mind or brain, whether as a result of an illness, or external factors such as alcohol or drug use?
· 2) Does the impairment mean the person is unable to make a specific decision when they need to?
· In England adults who lack capacity have decisions about care made to their overall benefit by the medical team.
MCA principles:
· A person must be assumed to have capacity unless it is established that they lack capacity.
· A person is not to be treated as unable to make a decision unless all practicable steps to help him do so have been taken without success.
· A person is not to be treated as unable to make a decision merely because they have made an unwise decision.
· An act, or decision made, under the act for or on behalf of a person who lacks capacity must be done, or made, in their best interests.
· Before the act is done, or the decision is made, regard must be had to whether the purpose for which it is needed can be effectively achieved in a way that is less restrictive of the person’s rights and freedom of action.
Children:
>18 = adult, no person can provide consent on behalf of another adult.
<18 = Parent or legal guardian has the right to provide consent:
Parent or legal guardians must act in the child’s best interest and where they don’t the medical team can apply for a court order.
16–17-year-olds – assumed to have capacity to consent to treatment
<16 “Gillick Competence” – Parental rights yield to the child’s right to make his own decisions when he reaches a sufficient understanding and intelligence to be capable of making up his own mind on the matter requiring decision. Although a child can give consent, they cannot refuse consent to a treatment and can be overruled by their parents.
Treatment without consent:
· Emergency situation to save life, patient incapacitated. May be unconscious
· Requires another medical procedure during an operation, waiting would be detrimental to patient
· Severe mental health and lack capacity to consent: dementia, schizophrenia, bipolar disorders.
· Severe mental health, attempted suicide or self-harm whilst competent but refusing treatment.
Even in emergencies there is still a presumption of capacity
Describe the anatomical pathways along which pain is transmitted and the physiological mechanism
Pain – unpleasant sensory and emotional experience in association with tissue damage.
Nociception – the neural process of encoding noxious stimuli though multiple ascending and descending pathways from the spinal cord to corticothalamic networks (cerebral cortex and thalamic nuclei).
Nociceptors: the peripheral receptors for pain; terminals of Aδ and C nerve fibres
Anterolateral pathway
- Contains the:
A) Spinothalamic tract (STT) à ascending pathway. These neurons = rapid neothalamic pathway which is sensory-discriminative (“where it is that hurts”)
B) Spinoreticular tract (SRT) à ascending and descending pathway. These neurons = slow palaeothalamic pathway which is the negative component of pain (“pain is unpleasant and worrying”).
Ascending input from spinal cord is balanced by descending modulation in brain.
CST =corticospinal tract LC = locus coeruleus PAG =periaqueductal grey PBN, parabrachial nucleus RF = reticular formation
Neuronal Electrophysiology
Depolarisation (less negative) membrane potential of neurons = action potentials = electrical signal carried through neuron.
1) Resting membrane potential at ~-70mV
2) Stimulus and threshold met at -50mV (all or nothing rule)
3) Depolarisation of membrane (A) (Na+ channels open)
4) Repolarisation of membrane (B) (K+ channels open)
5) Refractory period (C) (no action potential can fire) – hyperpolarisation
6) Resting membrane potential at -70mV
The change in membrane potential activates voltage-gated calcium channels
influx of calcium into the neuron
initiates signalling cascade for further neuronal transmission
Describe the nature and factors that give rise to stability of the hip, knee, anatomical ankle, subtalar and talocalcaneonavicular joints within the limb and understand the rationale for clinical examination of each joint
See anatomy
Describe the main transmission routes of bacteria and viruses in hospitals and methods of prevention of spread
Pathogens are mainly transmitted by direct contact with healthcare workers, patients or indirect contact with contaminated surrounding areas.
The main pathogens that are contracted in a healthcare setting are multi drug resistant pathogens (MDR) pathogens eg/ MRSA - Methicillin-resistant Staphylococcus aureus - a bacteria that are resistant to many widely used antibiotics.
The main RF for healthcare acquired infections are
Immunosuppression
Older age
Longer and more frequent stays to a healthcare facility
Comorbidity
Mechanical ventilation support
Invasive procedures
Indwelling devices
ICU
The main infection prevention and control measures
Correct disposal of clinical waste, sharps and bodily fluids
Correct management of clinical environment and medical equipment
High level of ventilation
Correct laundry management
Food hygiene management
IPC measure education for healthcare workers
Correct hand hygiene
Correct PPE
Ensure healthcare workers have adequate immunisations
Correct antibiotic use (to prevent AB resistance)
Testing patients for
infections (eg/ COVID)
Describe the normal structure of bone and how it is maintained
A typical long bone consists of the following regions:
The diaphysis is the shaft of the long bone
The epiphyses are the distal and proximal ends of the bone
The metaphyses are the regions in a mature bone where the diaphysis joins the epiphysis. In a growing bone the metaphysis is the region occupied by the epiphyseal growth plate.
Articular cartilage is a thin layer of hyaline cartilage that covers the epiphyses. It reduces the friction at the joints and acts as a shock absorber at freely moveable joints.
The periosteum is a tough layer of dense irregular connective tissue surrounding the bone surface where it is not covered by the articular cartilage. It contains the osteogenic progenitor cells and as these differentiate into osteoblasts they allow the bone to grow in thickness. The periosteum also helps to protect the bone, assists in fracture repair, helps nourish the bone tissue and serves as an attachment point for tendons and ligaments.
The medullary cavity in the centre of the bones is sometimes called the marrow cavity, and is the space within the diaphysis that contains the bone marrow. There are two types of bone marrow found in the medullary cavity:
Red marrow produces red and white blood cells and platelets (haemopoietic tissue)
Yellow marrow contains fat and connective tissue and produces some white blood cells.
The endosteum is a membrane that lines the medullary cavity and contains bone-forming cells; it is the
equivalent of the periosteum surrounding the outside of the bone. It serves as the site of formation for new bone and contains the osteogenic precursor cells.
Compact bone
Compact bone forms the outer layer of all bones, where it provides support and protection to the spongy bone in the centre and resists the stresses produced by weight and movement.11
It is formed of collagen which is impregnated with inorganic calcium salts, giving its exterior hardness. Compact bone is organised into osteons, sometimes called Haversian systems. In the centre of each osteon there is a central canal (Haversian canal) that runs longitudinally through the bone; the blood and lymph vessels and nerves run in these central canals.
Around the central canal the bone is arranged into concentric layers (lamellae), which are rings of calcified matrix. Osteocytes lie within spaces (lacunae) between the layers. Lacunae are connected via small channels called canaliculi in which finger-like projections of the osteocytes extend. The canaliculi form a complex branching network of small channels that connect with canaliculi and also with the central canal. This allows for the movement of blood-borne nutrients and oxygen to diffuse through the bone and for waste products to diffuse back to the blood vessels. The blood vessels of the central canal are connected to the periosteal vessels on the surface of the bone by perforating (Volkmann) canals , which also connect with the internal medullary cavity.
Spongy Bone
Spongy bone does not contain true osteons and consists of lamellae arranged into an irregular lattice of thin interconnecting struts (trabeculae). The spaces between the trabeculae are filled with red or yellow bone marrow, which is responsible for the production of blood cells. Within each trabecula osteocytes lie in lacunae with radiating canaliculi, much like in the osteons of the compact bone. The osteocytes in the spongy bone trabeculae receive their nutrients directly from the blood circulating through the medullary cavity.
Spongy bone makes up the majority of bony tissue in the short, flat and irregularly shaped bones and the epiphyses of the long bones, and lines the medullary cavity of the diaphysis of the long bones.
The orientation of the trabeculae in spongy bone is along the lines of stress, like the osteons in compact bone. This characteristic helps bone resist stresses and the transfer of force without breaking. Spongy bone is located where bones are not heavily stressed or where the stresses are applied from many directions, as this type of bone has both flexibility and strength. Spongy bone has a higher rate of turnover than compact bone, and so responds to the changing stresses placed on it faster than compact bone does. For this reason osteoporosis is more evident in bones that have a high proportion of spongy bone, such as the vertebrae and neck and head of the femur.
Spongy bone reduces the weight of the skeleton, so that the muscles acting on the skeleton do not have to work as hard. In the adult the spongy bone and its red bone marrow is the only site of haemopoiesis, especially the spongy bone of the pelvis (hip), ribs, sternum (breast bone), vertebrae and the ends of the long bones.
Bone Remodelling
Remodelling is a combination of osteoclast activity (resorption) and osteoblast activity (formation) replacing old bone tissue with new.
Remodelling is distinct from modelling (construction of new bone) which results in a net gain in bone mass.
Remodelling occurs along lines of force generated by mechanical stress, and incorporates 4 phases:
Activation: Resting bone surface is converted to a remodelling surface. Osteoclast precursors are recruited and fused into multi-nuclear osteoclasts 3-6.
Resorption: Osteoclasts erode bone matrix using acidification and proteolytic digestion within discrete scallop-edged Howship’s lacunae, subsequently leaving the resorption site or undergoing apoptosis.
Reversal: Once osteoclasts have resorbed the bone matrix, osteoblasts are recruited to the bone surface.
Formation: Osteoblasts replace the resorbed bone with new osteoid (un-mineralised collagen matrix) providing the basic structure for mineral deposition (predominantly hydroxyapatite). This matrix gradually hardens to form bone.
Resorption takes ~30 days in cortical and ~43 days in trabecular bone.
Formation takes ~90 days in cortical and ~145 days in trabecular bone.
In situations where remodelling is high, bone fragility can increase.
Resorption and new bone formation are normally well balanced, but where resorption is increased, a basophilic lesion occurs (the cement line) where remodelling is obvious histologically as new bone fills a resorbed cavity.
This remodelling cycle is the same for both compact cortical bone and the trabecular network of the internal spongy bone. Uncoupling bone resorption from bone formation leads to the bone conditions with a loss or increase in the body’s bone mass, as seen in osteoporosis, osteomalacia or Paget disease
Describe the difference between “Illness” (psycho-social) and “Disease” (bio-medical) in relation to a consultation
Psychosocial illness happens when someone with a mental health condition interacts with a social environment that presents barriers to them getting the same opportunities as others. Some psychosocial conditions are:
· Anxiety
· Depression
· PTSD (post-traumatic stress disorder)
They are disorders that affect your mood, thinking and behaviour.
In terms of a consultation this could present some problems, such as their capacity being affected if their ability to think is being affected. It may also make it harder for patients to open up to their doctor.
A disease has a specific result on a body part or function. This means that a disease can be specifically diagnosed whereas an illness is a lot harder to properly diagnose as it is a mental health condition. A disease is a pathological process where there is a deviation from the biological norm. An illness is a perceived feeling of pain or discomfort and it is hard to tell how severe this illness is.
