Musculoskeletal ESA Stem

• Function of the skeleton– Support and muscle attachment– Protection– Movement– Haemopoietic– Mineral storage

• Main cells in bone and their function– Osteoblasts – secrete bone– Osteoclasts – breakdown bone– Osteocytes – inactive osteoblasts • trapped by matrix

• Types of bone and where they are found in a typical bone– Compact/cortical bone – outside– Trabeculated/spongy bone – inside

• What is Heterotopic bone– Abnormal bone growth

• Name and briefly describe 2 methods by which osteogenesis occurs– Intramembranous

• Laying down of bone directly in primitive CT or mesenchyme – no cartilage precursor

• E.g. Flat bone of skull, clavicle

– Endochondral• Ossification of pre existing cartilage model• E.g long bones

• Describe the process of endochondrial osteogenesis– Chondrocytes under hypertrophy and secrete ECM– ECM is calcified resulting in chondrocyte cell death– Osteogenic buds invade dead cartilage• Blood vessels and osteogenic cells

– Osteoblasts develop and secrete more bone matrix that is mineralised

• 3 main classifications of cartilage– Hyaline cartilage– Elastic cartilage– fibrocartilage

• How does bone growth occur– Epiphyseal cartilage between metaphysis and

epiphysis of long bones– Growth of cartilage provides growth in length of

bone– Endochondral ossification occurs to convert

epiphyseal cartilage to bone

• Stages of bone repair– Haematoma– Granulation tissue– Callus formation– Lamellar bone formation– Remodelling of lamellar bone

You are asked to examine a little girl who has been brought to A&E after allegations of child abuse have been made against her mother. The child has a Hx of many visits to A&E with broken bones. On examination you notice that her scelera have a blue tint and that her joints are hyper mobile and that her teeth are very malformed.

• What is your suspected diagnosis and underlying pathology– Osteogenesis imperfecta (type 1)– Genetic – defective collagen type 1

• Decreased cross-linking = decreased strength and stability

• How will you investigate– Genetic test– DEXA scan– MRI/CT– Skin punch biopsy

• How will you treat this little girl– bisphosphonates

40 yr old patient Henry Marchal attends GP clinic complaining of pain in the bones of his legs. You take a Hx and discover he’s had multiple fracture recently and developed arthritis and he is becoming bow legged

• What is your DDx– Osteoporosis– Osteomalacia– Paget’s disease

• You also notice that he has a very large head, what diagnosis do you suspect– Paget’s disease

• What is the pathology of paget’s disease– Increased osteoclast activity– Compensatory increase in osteoblast activity– Increase in amount of woven bone (brittle)

• How will you investigate– Isotope bone scan– DEXA– X-Ray

• How will you treat– bisphosphonates

72yr old woman, Thespina Walsh, comes into A&E with a broken hip and wrist after falling at home. X-Ray reveals fracture of her radius with posterior displacement

• What is this type of fracture called– Colle’s fracture

• You suspect Thespina has osteoporosis, what are the risk factors– Smoking– Post-menopause– Malabsorption– Vitamin D defiency– Hyperparathyroidism

• What investigations will you perform– X-Ray– DEXA– CT

• How will you manage Thespina– Lifestyle – fall prevention– Calcium and vitamin D supplements– bisphosphonates

A mother attends GP clinic with her 6yr old son, Charlie Heskin, worried because Charlie’s legs are very bowed and he has a very waddling gait and pain in his legs. You suspect rickets (osteomalacia)

• What are the causes of rickets– Vitamin D deficiency– Calcium deficiency– Genetic

• What is the pathophysiology– Inadequate bone mineralisation– Enlarged growth plates

• How will you confirm your diagnosis– Bloods – increase alkaline phosphatase, decreased Ca and

PO4– X-ray – lytic lesions

• 3 types of joints, describe and give example– Fibrous• Surfaces joined by fibrous tissue• E.g skull sutures, sacrum

– Cartilaginous• Surfaces joined by cartilage• E.g costal cartilages, pubic symphysis, IV discs

– Synovial• Free movement• E.g shoulder, knee

• 5 features of a synovial joint– Joint capsule– Synovial membrane– Synovial fluid– Joint space/cavity– Articular surfaces covered by hyaline cartilage

43yr old female patient, Ardas Lahcam, comes in complaining of both of her hands being tender, stiff and painful. She says that they are worse in the morning and she has difficulty doing simple tasks in the morning.

• What do you suspect?– Rheumatoid arthritis

• What is the pathology– Autoimmune inflammation of joints and surrounding tissue– Hyperplasia of synovial membrane– Spreads to cartilage causing damage

• How will you confirm your diagnosis– Examination

• Swollen, warm, spongy joints– Investigations

• Anti CCP antibody (specific)• Rheumatoid factor (sensitive)• ESR, CRP• Imaging – USS, MRI, CT

• How will you treat Ardas– Initially – NSAIDs, prednisolone, disease modifiers (methotrexate)– As disease progresses – anti TNF, monoclonal antibodies

55 yr old male patient, Hpesoj Nikseh, comes in with pain and stiffness in his right knee that is swollen and worse at the end of the day or post exercise. You examine him and find crepitations on the joint and loss of range of movement

• What is the diagnosis and the pathology process underlying it– Osteoarthritis– Breakdown/wearing away of cartilage – bone rubs on bone – microfractures –

abnormal overgrowths – osteophytes• What investigations will you do

– X-ray/MRI/Arthroscopy• loss of joint space and bony spurs

• How will you treat– Lifestyle factors - weight– NSAIDs– Steroid injections into joint– Physiotherapy– Surgery

• Trim damaged cartilage• Osteomy (change alignment of bone)• Surgical fusion• Joint replacement

• List and describe the 3 main types of mechanical joint injury– Dislocation• Complete separation of articular joint surfaces

– Subluxation• Partial separation of articular joint surfaces

– Sprain• Stretching of capsule and ligaments

15yr old male patient, Mada Hslaw, attends clinic with pain and stiffness of his right wrist. On examination the joint is swollen, warm, red and tender when pressed on. Mada sheepishly informs you that his wrist “gets alot of use”. You suspect bursitis

• What is the pathology of Bursitis– Acute or chronic inflammation of the bursa

• What are 4 potential causes of bursitis– Chronic overuse– Trauma– Infection– Excessive pressure

• How will you treat Mada– NSAIDs and rest the joint

20 yr old Jobin Hesicki attends clinic with pain and stiffness in his sacroiliac joints and back that is worse in the morning but gets better after exercise. He also has been feeling very tired. You suspect ankylosing spondylitis

• what is the underlying cause and pathophysiology– Genetic component – HLA 1 linked– Lymphocytes and plasma cells infiltrate spinal and pelvic joints and cause

damage – autoimmune• What is the progression of this disease

– Ossification of annulus fibrosis leading to fusion of vertebrae (bamboo spine on X-ray)

• What investigations will you do to confirm your diagnosis– Blood – inflam markers (ESR and CRP)– HLA testing– X-ray

• How will you treat Jobin– Anti-TNF and NSAIDs

47yr old Alvin Lest attends clinic complaining of throbbing/crushing pain at night in his right MTP joint. Alvin’s BMI is 33 and on examination the joint is warm and red. You suspect gout

• What is the pathology underlying gout– Overproduction/elimination problem of uric acid– Accumulation in synovial fluid causes crystal formation– Inflammation

• What investigations – Serum urate and creatinine– Synovial fluid – uric acid– X-ray

• Treatments– Lifestyle changes – avoid alcohol and purine rich foods– NSAIDs– corticosteroids

• What is the basic contractile unit of muscle– Sarcomere

• What is the sliding filament theory– The thick myosin and thin actin filaments of the

sarcomere slide past each other to shorten length of sarcomere and cause contraction

• Describe the cellular process of muscle contraction– In resting cell actin binding sites are blocked by tropomyosin– AP causes increased [Ca]i – released from SR– Ca binds troponin causing conformational change in actin filament resulting in

movement of tropomyosin– Actin binding sites are uncovered and myosin heads bind = cross bridge

formation– Energy (ATP – ADP) causes myosin head to bend and pull actin filament– Myosin remains bound to actin until binding of ATP causes release– Cross bridge cycling continues as long as Ca and ATP are present

• How does muscle relaxation occur– Removal of NMJ stimulation– Decrease in [Ca]i – pumped back into SR– Ca stripped from troponin– Tropomyosin moves to cover actin binding sites thereby preventing cross bridge

formation

• How is the strength of a muscle contraction controlled– The number of motor units recruited• Increased motor units = increased strength contraction

• What is a motor unit– Collective term for all the muscle fibres innervated

by a single terminal nerve• Each muscle fibre has 1 nerve• Each nerve has multiple muscle fibres

• What are the different types of muscle fibres and the characteristics of each type– Slow oxidative (type I)

• High mitochodria and capillaries• Aerobic• Fatigue resistant (endurance)• Example - postural

– Fast oxidative (type IIa)• High mitochondria and capillaries• Aerobic• Moderate fatigue resistance• E.g. walking

– Fast glycolytic (type IIb)• Low mitochondria and capillaries• Anaerobic• Fatigue easily• E.g. Rapid jerky movements

• Effects of ageing on musculoskeletal system– Muscles

• Shrink and atrophy• No and size of fibres decrease• Take longer to respond• Fatigue more quickly and longer recovery

– Decreased blood flow

– Bone• Mineral content decreases• Lose bone mass

– CT• Tendons and cartilage lose water content

– Stiffer and more susceptible to stress

• Ligaments less elastic

• 3 pathological processes affecting muscle– Polymyositis (dermatomyositis)– Myasthenia gravis– (Duchene’s) Muscular dystrophy

32yr old teacher, Andrea Walsh, attends GP clinic complaining of weakness in her right arm and difficulty keeping her eyes open at the end of the day and is especially bad on sunny days. You suspect myasthenia gravis.

• What is the pathological process behind this disorder– Autoimmune anti-ach receptor antibodies– Block ach binding and lead to ineffective NMJ transmission

• What investigations would you perform to confirm– Blood – antibodies– Single fibre electromyography– Tesilon test

• Give cholinesterase inhibitors• Temporarily increase ach levels and nmj = immediate improvement

– CXR /CT - check for thymoma• Ix confirms myasthenia gravis, how would you treat

– Lifestyle advice– Anticholinesterase medication– Corticosteroids and azathioprine– thymectomy

45yr old patient, Marsha Sosef, attends GP clinic complaining of feeling very run down and tired and having muscle pain and difficulty rising from a chair and has noticed a rash around her eyes and knuckles. After a few more questions you discover she has also lost weight and having some difficulty swallowing. You suspect dermatomyositis

• What investigations will you do to confirm– Bloods – anaemia, creatinine kinase– Electromyography – abnormal fibrillation at rest– Muscle biopsy – mandatory!!• Inflammation

• How will you treat Marsha– Corticosteroids– Azathioprine or cyclophosphamide

Josephine Sanders attends GP clinic with her 3yr old son. She is very worried because he is still not walking and having difficulty picking things up and the only way he can stand is by climbing his hands up his legs (Gower’s sign). She has also noticed his calves are very swollen looking (pseudohypertrophy). Josephine also tells you that her mother had a brother who died very young with similar symptoms

• What pathology are you suspecting– Duchenne’s muscular dystrophy

• How is this disorder inherited– X-linked recessive

• What is the underlying pathology– Absence of protein dystrophin– Replacement of muscle with fat

• What investigations will you do to confirm– Genetic– Blood – grossly raised creatinine kinase– Electromyography– Muscle biopsy

• How will you manage this condition– No cure– Physiotherapy– Respiratory support

• Stages of normal walking gait– Stance phase

• Double stance• Heel strike• Midstance• Toe-off• Double stance

– Swing phase (pelvic tilt allows limb to swing free of the ground)• Acceleration• Deceleration

• How does this change with running– Double stance becomes double float

• 3 examples of abnormal gaits– Trendelenberg gait

• Paralyzed gluteus medius• Contralateral pelvic drop• Compenstory trunk lurch towards affected side

– Dorsiflexor gait (foot drop)• Flex knee and hip in swing phase• deep peroneal nerve

– Paralyzed quadriceps• Walking on level surface – normal• Uneven surface/running buckle into flexion