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

Acetabulum – Posterior Approach

Acetabulum – posterior approach

* position – lat. decubitus

* incision – long. incision centered on GT extending from just below iliac crest ot 10cm below tip of GT

* no internervous plane

* dissection
– incise subcut. fat
– incise fascia lata in line with skin in lower 1/2 of wound & extend sup. along ant. border of GMax
– ID sciatic n.
– retract split edges of fascia to reveal piriformis & short ER
– IR leg to put short ER on stretch
– detach short ER from insertion on femur
– elevate GMed from outer side of ilium
– troch. osteotomy if more visualization needed
– incise capsule

* dangers
– sciatic n. – ID b4 cutting short ER & protect with short ER

– IGA – exits pelvis under piriformis & turns up to supply GMax

Ulna – Approach

Ulna – approach

* position – supine with forearm across chest & tourniquet

* incision – longitudinal over subcut. border of ulna

* internervous plane – ECU (PIN) & FCU (ulnar n.)

* dissection
– incise deep fascia
– find interval btw ECU & FCU
– middle 1/3 – ECU fibers may need to be divided from bone
– at olecranon – FCU & anconeus run along plane of dissection
– incise periosteum
– prox. 1/5 of ulna – insertion of triceps may need to be detached to gain access to bone

* dangers
– ulnar n. – travels under FCU; should be identified proximally as it emerges btw 2 hds of FCU b4 stripping FCU from bone
– ulnar art. – runs on radial side of ulnar n.

Radial Head Fractures

Radial Head Fractures

Type I-undisplaced
Type II-Displaced single fragment
Type III-Comminuted
(IV-Johnston-assoc. with elbow dislocation)

I-early ROM
-stable elbow with full ROM= conservative
-block to rotation,assoc. Injury potentially compromising elbow stability (ie. MCL ,interosseous membrane, coranoid fracture, elbow dislocation)=consider ORIF
III-excision vs. Replacement
-excision reserved for those with isolated comminution (ie-no forearm or wrist pain, no assoc. Instability or injuries contributing to elbow instability-MCL/CORANOID)

Slipped Capital Femoral Epiphysis (SCFE)

Approach to Slipped Capital Femoral Epiphysis

– there is a narrow window when this happens – just in the growth spurt area (11-13 in girls, 13-15 in boys)
– may be related to endocrine abnormalities: hypothyroid, hypopituitarism, hypogonadism, increased growth hormone; Also seen in FAT kids
– The key physical finding is an obligatory external rotation of the hip when flexing

Defined based on if the kid can walk on it or not (stable or unstable); chronic slips tend to be stable; acute slips tend to be unstable. Note that the stable ones can acutely become UNstable – therefore, if the kid arrives in emerg, walking, with a stable slip, he gets immediate BEDREST and an OR as soon as can be arranged. He DOES NOT GET DISCHARGED HOME ON CRUTCHES.

Southwick�s Femoral head – shaft angle: measured on the frog lateral. Should be 10o; increased in slips
Klein�s line – a line drawn along the superior border of the neck should pass through part of the epiphysis in the normal hip on an AP pelvis. In slips it misses the epiphysis superiorly. (also called Trethovan sign)
Look for increased metaphyseal density on the AP (superimposition of the head behind the metaphysis)

– single pin fixation
– kids with endocrine abnormlaties get prophylactic pinning of the other side; this is the only indication for prophylaxis
– the hugely displace slips should probably have a bone scan to document avascularity of the head, then a GENTLE closed reduction maneuver (according to Morrissey) prior to fixation

Beware AVN and chondrolysis – these are the two main complications; they generally do not occur in untreated slips.

What happens when their head collapses from AVN?
– rule out sepsis (clinically, bloodwork)
– then, assess where the screw is – Is it in, or nearing the joint surface? then you need to consider taking it out.
– then decide, What about the physis – has it closed yet? Get a CT scan to see if the physis has fused yet. If it has, you are safe to take the screw out. If it has not fused, you can do one of two things:
1. revise the screw to a shorter screw and hope that the thing will heal before the progressive collapse reveals the screw tip to the joint.
2. do an open bone peg epiphyseodesis.

What about ruling out �endocrine abnormalities�?
– the obese boys who get this when they�re 14 are probably okay.
– but any boy

Thumb Metacarpal Fractures

Thumb Metacarpal #’s

Metacarpal Shaft Fractures

– uncommon, owing to the strength of cortical bone – most of the force is transmitted to the base.
– when they do occur, displacement is common with dorsal angulation due to the strong volar pull of the thenar muscles and FPL

– most can be treated with closed reduction then thumb spica cast
– K-wire if you deem it to be too unstable (whatever that means) – neither Jupiter or Rockwood and Green indicate what is acceptable alignment. If you consider it like the other metacarpals, it is more mobile than all the rest, but it�s function is more critically important.
– rarely is ORIF needed.

Metacarpal Base Fractures

– Classified by Green and O�Brien
I. Bennett�s fracture (intra-articular, single fragment)
II. Rolando�s fracture (intra-articular, comminuted)
IIIA. Transverse base fractures (extra-articular)
Oblique base fractures (extra-articular)
IV. Salter II injury in children

Bennett�s Fractures (Green-O�Brien I)

– the base of the metacarpal is pulled radially and dorsally by the force of abductor pollicis longus, the thenar muscles, and FPL. The adductor pollicis tends to lever the base into abduction, but Jupiter suggests that this is an overestimated effect. The volar, ulnar lip of the base is held down by the strong volar anterior oblique ligament.

– there are many proponents of closed reduction and casting – this fails to hold the fragment, but the supporters suggest that the end result is not bad.
– more reliable treatment is closed reduction and percutaneous fixation – the reduction is by traction, adduction, and a dorsally applied, volarly directed force applied to the base to approximate it with the volar, ulnar lip fragment. This is then secured with two K-wires – either to the trapezium, or to the second metacarpal.
– what constitutes an �acceptable� reduction remains unresolved – aim for 2 mm gap or less.

Rolando�s Fracture (Green-O�Brien II)

– originally described as having, in addition to the volar lip fragment, a large dorsal fragment.

– depends on severity of comminution
– ORIF if large fragments exist that might accept fixation
– external fixation or simple casting with early motion if severely comminuted

Extra-Articular Fractures (Green-O�Brien IIIA, IIIB, IV)

– thankfully, the most frequent fracture of the metacarpal base.

– closed reduction and thumb spica casting is usually sufficient; �One should resist the temptation to overtreat these extra-articular fractures.� The Rockwood and Green authors suggest the up to 30o of angulation is well tolerated.
– percutaneous pinning may be required for the long oblique fractures (have a tendency to shorten).