Archive for category: Uncategorized

Core topics in orthopaedics

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

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

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

Treatment:
– 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

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

Xrays:
– 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

Histology:
– 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

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

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.

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)

Treatment
– 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