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

Fibula – Approach

Fibula – approach

* position – supine with sandbag under buttock or lateral

* incision – long. incision just post. to fibula beginning behin lat. malleolus & extending to level of fibular head

* internervous plane – peroneal muscles (SPN) & flexor muscles (tibial n.)

* dissection
– find post. border of BF as it sweeps down past knee before inserting on head of fibula
– incise fascia & ID CPN
– trace course of CPN as it winds around fibular neck
– mobilize CPN from groove on back of neck
– develop plane btw PL & soleus
– incise periosteum of fibula
– strip muscle off fibula
– strip interosseous membrane subperiosteally from prox. to distal

* dangers
– CPN – winds around neck of fibula
– dorsal cut. branch of SPN – ID at jxn of distal & middle 1/3 of fibula
– peroneal art. – terminal branches lie close to deep surface of lat. malleolus
– lesser saphenous vein

Talocalcaneal Joint – Lateral Approach

Talocalcaneal joint – lateral approach

* position – supine with sandbag under buttock & table tilted 20-30 deg. away from surgeon

* incision
– curved incision 10-13 cm long on lat. aspect of ankle starting 4 cm above tip of lat. malleolus on post. border of fibula
– follow to tip of fibula & curve forward passing over peroneal tubercle parallel to course of peroneal tendons

* no internervous plane

* dissection
– avoid sural n. & short saphenous vein as they run just post. to lat. malleolus
– incise deep fascia in prox. wound to expose peroneal tendons
– continue to incise fascia following tendons
– incise inf. peroneal retinaculum in line with PB
– incise fibrous sheath over PL
– retract peroneal tendons ant.
– ID calcaneofibular lig. running from lat. malleolus to lat. surface of calcaneus
– ID subtalar joint & incise capsule

* dangers
– sural n. & short saphenous vein

Clavicle Fractures

Clavicle Fractures

3 Groups based on thirds
medial (5 %),middle (85%),distal (10 %)
*consider ORIF-open,n-v injury,skin compromise,ipsilateral scapula or flail chest

Distal Clavicle Classification
(Neer and Rockwood)
Type I-lateral to intact C-C ligaments (C/T)
Type II-complex injuries (30% non-union without surgery)
medial fragment separated from C-C ligaments by A-obligue # (ie. Iig attached to lateral fragment) or B-ligaments cause segmental avulsion from underside of clavicle
Type III-Intra-articular A-C joint fractures

Type I and III-Symptomatic treatment

Thoracolumbar Spine Fractures

Thoracolumbar Spine Fractures

Three column theory (Denis, 1984)
Ant.-ALL and ant. 2/3 vertebrae
Mid.-post. 1/3 body and PLL
Post.-bony arch, inter/supra spinous and flavum

Stability based on 2 columns.
Divided into 4 categories:
1) Compression
-compression of ant. column with intact middle column and post.
-post. column fails under tension with >40 to 50% loss of ant. height
A-failure of both endplates (16%)
B-failure of sup. endplate (62 %)
C-failure of inf. endplate (6 %)
D-both endplates intact (15 %)

2) Burst Fractures
-compression failure of ant. and middle columns +- post. columns
-retropulsion common
A-both endplates (24 %)
B-sup. endplate (49%)
C-inf. endplate (7%)
D-Burst/rotation injury (15%)
E-Burst/lateral flexion injury (5%)

3) Seat-belt injuries
A-one level bony injury (Chance)
B-one level ligamentous injury
C-two-level injury through bone in middle column
D-two-level injury through ligamentous middle column

4) Fracture-dislocations
-failure of all 3 columns
-high rate of neurologic injury
-M/P columns fail in tension and rotation and A column in flexion

12 – Humeral Diaphysis

A-Simple fracture
12-A-1 spiral
12-A-2 oblique (>30 degrees)
12-A-3 transverse (<30)
12-B-1� spiral wedge
12-B-2 bending wedge
12-B-3 fragmented wedge
C-Complex Fracture
12-C-1 spiral
12-C-2 segmental
12-C-3 irregular