Core Topics

Core topics in orthopaedics

AO Classification

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


Unicameral Bone Cyst (UBC)

Unicameral Bone Cyst (UBC)

– solitary, fluid-filled cystic lesions located in metaphysis of long bones near physis in kids & adolescents
– predominantly proximal femur & proximal humerus

Signs & Symptoms:
– usu asymptomatic
– pathologic # associated with minimal trauma

– radiolucent, trabeculated lesion with well-defined borders surrounding by sclerotic margin
– ‘fallen leaf’ sign in pathologic #

– lined with loose connective tissue membrane containing small numbers of fibroblasts, giant cells & hemosiderin-laden macrophages

– 15% will heal after # with observation alone
– treat # as you would for most #s of that region
– once # healed, aspiration & steroid injections (x 3)
– curettage & bone grafting improves healing rate & provides mechanical support



– 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

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

– 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

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

Aneurysmal Bone Cyst (ABC)

Aneurysmal Bone Cyst (ABC)

– solitary expansile lesion located in metaphysis of long bones, flat bones & vertebrae
– presents in 2nd decade
– cysts filled with blood

Signs & Symptoms:
– pain with tenderness & swelling at the site of the lesion

– expansile eccentric lesion surrounded by a thinned cortex with periosteal new bone formation
– CT/MRI – characteristic ‘fluid-fluid’ level
– beware of telangiectatic osteosarcoma – has fluid-fluid levels but far more aggressive looking

– blood spaces separated by cellular septa lacking an endothelial cell lining & containing a variety of cells such as fibroblasts, multinucleated giant cells & histiocytes & metaplastic bone
– large solid cellular areas may be seen

– excision, curettage & bone grafting
– cryosurgery or chemical ablation may be used

Cervical Spine – Anterior Approach

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

Knee – Posterior Approach

Knee – posterior approach

* position – supine & tourniquet

* incision
– start lat. over BF & bring incision obliquely across popliteal fossa
– turn down over med. head of gastroc.

* no internervous plane

* dissection
– reflect skin flaps
– expose lesser saphenous v.
– running lat. to vein is med. sural n. (branch of tibial n.)
– incise fascia of popliteal fossa just med. to lesser saphenous v.
– trace med. sural n. back to tibial n.
– dissect up to apex of popliteal fossa following tibial n.
– at apex, CPN separates from tibial n.
– ID popliteal art. & vein
– art. has 5 branches — 2 superior, 2 inferior & 1 middle genicular art.
– vein lies med. to art. as it enters popliteal fossa from below
– curves lying directly post. while in fossa
– moves to posterolat. side of art. above knee joint

> posteromed. joint capsule
– detach origin of med. head of gastroc. from back of femur
– retract head lat. & inf.
– expose posteromed. joint

> posterolat. corner
– detach origin of lat. head of gastroc. from lat. fem. condyle
– develop interval btw gastroc. & BF
– incise joint capsule

* dangers
– med. sural n. – lies lat. to lesser saphenous v. so incise fascia med. to vein
– tibial n.
– popliteal vessels

MCQs – Basic 5

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.

Pelvic Fractures

Pelvic Fractures

B-Rotationally unstable; vertically and posteriorly stable
C-Rotationally, posteriorly and vertically unstable

A1-Fractures not involving ring, avulsion injuries
A1.1-Anterior superior spine
A1.3-Ischial Tuberosity
A2-Stable,minimal displacement
A2.1-Iliac wing fractures
A2.2-Isolated anterior ring injuries (four pillar)
A2.3-Stable,undisplaced, or minimally displaced pelvic ring #
A3-Transverse # of sacrum and coccyx
A3.1-Undisplaced transverse sacral #
A3.2-Displaced transverse sacral
A3.3-Coccygeal #

B-Rotationally unstable; vertically and posteriorly stable
B1-External rotation instability; open book injury
B1.1-Unilateral injury

31 – Femur Proximal

31-Femur Proximal

31-A-1 peritrochanteric simple
31-A-2 peritroch-multi fragments
31-A-3 intertrochanteric
B-Extra-articular-Neck Fractures
31-B-1 subcapital-min. displaced
31-B-2 transcervical
31-B-3 displaced subcapital
C-Articular-Head Fractures
31-C-1 split (pipkin)
31-C-2 split with depression
31-C-3 with neck fracture