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

Hip – Lateral Approach

Hip – lateral approach

* position – supine or lat. decubitus

* no internervous plane

* incision – 15 cm longitudinal incision centered over GT

* dissection
– incise fat & deep fascia in line with incision
– retract TFL ant. & GMax post.
– split fibers of GMed in direction of fibers in middle of GT
– split fibers of vastus lat.
– develop ant. flap of ant. GMed & vastus lat.
– detach muscles subperiosteally from GT or with flake of bone
– detach GMin with flap
– incise capsule (t-shaped)
– osteotomy of fem. neck
– extend capsulotomy
– remove fem. head
– complete exposure of acetabulum

* dangers
– SGN – runs btw GMed & GMin 3-5cm above upper border of GT
– more prox. dissection can cut nerve or produce traction injury

– fem. n. – vulnerable to inapporpriately placed retractors

– transverse branch of lat. fem. circumflex art. – cut as vastus lat. mobilized

Elbow Dislocations

Elbow Dislocations

Posterior-(80% post./posterolat.)
-CR with sedation +/- intra-articular local-test stability-splint 1-2 weeks
Anterior-rare; risk of NV injury

Clubfoot 2

Approach to Clubfeet – Late or Recurrent Deformity

Residual Deformity
– most commonly secondary to incomplete release, especially of the plantar fascia and short/long plantar ligaments
– make sure it is not neurologic in origin – tethered cord?
– was post-op casting and orthotic use sufficient
– Is there motor imbalance around the foot?
– Where is the anatomic pathology? Hindfoot equinus? Hindfoot varus? Forefoot/Midfoot adduction/supination?

Management – stiff deformity
– if young (less than 4) you can probably get away with repeating the posteromedial release (or whatever parts of it that you think are necessary to address the anatomic pathology)
– if older you need to think about osteotomies to help with the alignment. If curved lateral border, think about trying to shorten the lateral column with a Dwyer lateral closing wedge osteotomy with a release of the scar tissue that holds the cuboid medially. Or, a cuboid decancellation. Alternatively, if the hindfoot is still in a fair amount of fixed varus, you can do a medial opening wedge osteotomy of the calcaneus (if you don�t want to shorten the foot any more with a Dwyer)

Management – dynamic deformity
– if there is a dynamic adductus and supination that is reducible passively try tendon transfer. This is often due to incoordination of tib ant and posterior tib. Can do a split anterior tib transfer to base of fifth MT, or do a whole anterior tib transfer; or alternatively, bring tib post through interosseous membrane to third cuneiform.

Remember: the key is the age (and therefore the correctability) and the identification of what the pathology is (either dynamic or fixed). Above 4 years, really think about doing osteotomies.

MCQs – Hip 3

MCQs-hip 3
adduction deformity of the hip, postural scoliosis, and a valgus deformity of the knee may develop.

– the following are blocks to reduction of CDH: inverted labrum, pulvinar, capsule (hour glass constriction), ligamentum teres, psoas tendon (causes the hourglass constriction); acetabular version does not influence reduction.

– in a 4 year old with CDH, doing a closed reduction will be very hazardous for creating AVN.

– extreme abduction will cause AVN in CDH. Extreme hyperflexion may force the heads inferiorly within the acetabulum.

– a truly congenital dislocation of the hip (present at birth) is uncommon. It is more common on the left.

– indications for Chiari include coxa magna with subluxation laterally.

– in a child with CP, innominate osteotomy is inappropriate because acetabular deficiency is not the problem, at least not initially – this is a paralytic problem. Later on, there may be acetabular deficiency more POSTERIORLY – treat with Dega osteotomy.

– the following portends a worse prognosis in Perthes: whole head involvement, females (tend to get more head involvement), loss of containment, and the presence of metaphyseal cysts.

– the Caterrall “Head at Risk” signs for Perthes include: Gage’s sign, metaphyseal cysts, horizontal physis, lateral epiphyseal calcification, lateral subluxation. In the final analysis, age of onset beyond 8, and involvement of the lateral pillar may be the worst.

– for the older DDH kid with trochanteric overgrowth because of AVN, surgical alternatives to deal with the limp and trendelenberg include either a growth arrest of the GT if young, and if older, a distal transfer of the GT.

– the classic age for Perthes is 4-9, although it can appear in kids as young as 2, and as old as 12.

– Coxa breva secondary to Perthes is a result of AVN – the neck is short, and often in varus with trochanteric overgrowth. Do no treat this with a varus osteotomy. Abductor strengthening, and distal/lateral transfer of the GT may be helpful.

– the worst of the femoral neck fractures is the transepiphyseal (Delbert I). With dislocation of the head, the AVN rate approaches 100%. Rates for the remaining probably depend mostly on displacement, although the interesting thing is that the basicervical fractures (III) have an AVN rate of nearly 25%, which is very different than in the adults.

Scaphoid Nonunion Advance Collapse (SNAC)

Scaphoid Nonunion Advanced Collapse – SNAC Wrist

– similar in is natural history to SLAC wrist, with comparable stages of joint degeneration
– can occur after malunion or after established nonunion
– it is felt that degenerative arthritis is almost inevitable after a scaphoid nonunion
– the fact that this joint degeneration can occur even after healing of the scaphoid fracture emphasizes the precise role that the scaphoid plays in normal wrist kinematics.
– if the scaphoid shape or volume is altered (by malunion, or by nonunion and subsequent bony resorption), the process of degeneration can be initiated.
– ligamentous injury can also occur with scaphoid fracture and contribute to the pathogenesis of degenerative change
– with an unstable scaphoid fracture, the distal segment flexes, the proximal fragment extends under the influence of the lunate (if the scapholunate ligament is still intact). Joint congruity between the distal radius and scaphoid and between the scaphoid and capitate is decreased.


Stage I: Arthritis localized to the distal scaphoid and radial styloid

Stage II: Radioscaphoid plus scaphocapitate arthritis, but preservation of the lunocapitate joint

Stage III: Periscaphoid arthritis involving radiostyloid, distal scaphoid, scaphocapitate, and
lunocapitate joints.
Surgical Treatment – SNAC Wrist

Stage I: radial styloid
– radial styloid excision plus bone graft of scaphoid nonunion

Stage II: radioscaphoid, scaphocapitate
– proximal scaphoid fused to capitate and lunate with excision of distal scaphoid (Viegas)
– scaphoid excision, four-corner fusion

Stage III: radioscaphoid, scaphocapitate, lunocapitate
– scaphoid excision, four corner fusion
– wrist arthrodesis

In the end, comparison of results for motion, strength, and functional use does not demonstrate vast differences between any of the procedures. In general, proximal row carpectomy provides more motion, a little less strength, and progression of arthritis in some cases. Midcarpal fusion with scaphoid excision provides fair-good motion and strength equal to coemplete fusion, but with some risk of arthritis progression. Total wrist arthrodesis provides good strength, but leaves no motion