Archive for category: Uncategorized

The AO group has developed a comprehensive classification of fractures. The classification is arranged in order of increasing severity according to the complexities of the fracture, difficulty of treatment and worsening prognosis.

More detailed information about the classification can be obtained from AO Foundation

• AO Classification – General Principles
• 11 – Proximal Humerus
• 12 – Humeral Diaphysis
• 13 – Distal Humerus
• 21 – Radius/Ulna Proximal
• 22 – Radius/Ulna Diaphysis
• 23 – Radius/Ulna Distal
• 31 – Femur Proximal
• 32 – Femur Diaphysis
• 33 – Femur Distal
• 41 – Tibia/Fibula Proximal
• 42 – Tibia/Fibula Diaphysis
• 43 – Tibia/Fibula Distal
• 43 – Tibia/Fibula Malleoli

Adamantinoma

– 1o bone tumor with predilection for tibial diaphysis presenting during early adulthood

Signs & Symptoms:
– painful masses with variable symptom duration ranging from few months to few years

Xrays:
– well-circumscribed, eccentric, lytic lesions of tibial diaphysis
– may be multicystic lesion with surrounding sclerosis
– expansion of bone +/- intact cortex but no periosteal reaction

Histology:
– wide variety of histologic appearances
– basaloid pattern composed of groups of cells which peripherally have palisading epithelial cells
– hypocellular, poorly organized, fibrous connective tissue between islands of epithelial cells

Treatment:
– wide excision (limb salvage vs amputation)
– 20-25% metastasize to lungs

Cervical spine – anterior approach

* position
– supine with sandbag btw shoulder blades
– turn head away from incision
– HOB 30 deg

* landmarks
– hard palate = arch of atlas
– lower border of mandible = C2-3
– hyoid bone = C3
– thyroid cartilage = C4-5
– cricoid cartilage = C6
– carotid tubercle = C6

* incision – transverse incision at level of pathology extending obliquely from midline ot post. border of SCM

* internervous plane
– none superficially
– SCM (spinal accessory n.) & strap muscles (C1-3)
– btw L & R longus colli (segmental branches from C2-7)

* dissection
– incise fascial sheath over platysma in line with skin
– bluntly split platysma long. in line with fibers
– identify ant. border of SCM
– incise fascia ant. to SCM
– retract SCM lat.
– retract sternohyoid & sternothyroid with trachea & esophagus med.
– expose carotid sheath
– develop plane btw med. edge of carotid sheath & midline structures
– cut thru pretracheal fascia on med. side of carotid sheath
– 2 vessels connect carotid sheath with midline structures (sup. & inf. thyroid art.) –> may limit exposure above C3-4
– bluntly dissect heading med. to expose longus colli
– split longus colli long. over midline of vert. bodies
– retract lat.
– place marker & take xray

* dangers
– recurrent laryngeal n. – make be injured with deep dissection
– sympathetic n. & stellate ganglion – lies on longus colli just lat. to vert. bodies
– carotid sheath – protected by ant. border of SCM
– verterbral art. – lies in costotransverse foramen on lat. portion of transverse processes

MCQs-Basic 5
these proteoglycans (which are usually aggrecan) bind via a link protein to hyaluronic acid to form a proteoglycan aggregate.

– place plates on the tension side of fractures because they are loaded best in tension and can act as tension band system.

– forged cobalt chrome is stronger than cast cobalt chrome

– fatigue failure of a metal implant occurs with cyclic loading past the endurance limit, which is usually in the elastic range, not plastic range.

– titanium has a lower modulus of elasticity than cobalt chrome. It is less resistant to surface wear, making it a poor bearing surface. The histiocytic response to titanium is apparently less than for cobalt chrome.

– ossification of the embryo begins between 7 and 12 weeks.

– PTH is synthesized and secreted by the chief cells of the parathyroid gland.

– 1, 25 dihydroxyvitamin D (and 24,25 dihydroxyvitamin D) is made in the proximal tubule of the kidney

– 25 hidroxyvitamin D is made in the liver

– Vitamin D facilitates production of calcium binding protein in the intestinal mucosa – increases intestinal absorption of calcium.

– in stored blood, factor VIII is negligible at 72 hours, factor V by 3-5 days.

– massive transfusion with citrated blood – will cause hypocalcemia which can cause cardiac arrhythmias; hyperkalemia can result from broken down blood cells, but more common to have hypocalcemia.

– stress is defined as force/unit area (it is not the same measurement as load)

– disc degeneration; in the young adult – nucleus is 85% water, and the annulus is 78% water. The water content of both falls to about 70% with aging. This is largely due to changes in the proteoglycan and collagen network.

– warfarin acts to inhibit the production of vitamin K-dependent clotting factors – II, VII, IX, X. Metronidazole, septra, and cimetidine all prolong the PT by interacting with warfarin.

– methylmethacrylate monomer may have a direct effect on cardiac system (cardiodepressant); as the cement is mixed, it increases in volume about 3-5%; as the monomer polymerizes, the volume decreases 5-7%.

– malignant hyperthermia is caused by a uncontrolled release of calcium in the skeletal muscles from the sarcoplasmic reticulum.