52. humerus Flashcards
what travels through the supracondylar foramen in a cat
branch of brachial artery and median nerve
if cutaneous sensation is present in a dog with a humeral fracture and radial nerve neurapraxia how long will it regain motor function
1-6 weeks in most animals
normal scapulohumeral abduction angle
30 degrees50 degrees is considered abN and likely to have medial instability
humeral fracture location in dog vs cat
dog distal 44% and diaphyseal 42%cats diaphyseal 75%
whole proximal humeral epiphysis fuses with metaphysis at what age in cat vs dog
dog 7.5 - 12 monthscat 19-26 months
repair options for proximal humeral fractures
–two parallel pins (decr compression on growth plate and allow growth)–pins and tension band–lag screw
what force is the greater tubercle susceptible to
tension or pull from supraspinatus muscle during swing phase of gait cycle
T/Fthe proximal humeral metaphysis is an area of predisposition for primary bone tumors most commonly OSA
TRUE
cats and dogs humeral IM pin purchase
dogs—use medial aspect of the humeral condyle to increase length of pin and bone purchasecats–aim for center diaphysis right above olecranon fossa
percentage of pins placed nondirected retrograde that penetrate shoulder joint
20%recommend normograde placement (distal to proximal) to directed retrograde to the craniolateral surface to avoid joint placement
tension side of humerus proximally and distally
proximal–craniolaterallydistally–caudomedially
why is medial plate placement advantageous for fractures involving the distal third of the humerus
–tension side of bone–medial approach has less ST dissection–straighter shape of the medial epicondylar crest requires minimal plate contouringDISADVANTAGE–no access proximally, neuromuscular structures
define supracondylar humeral fracture
fractures where the fracture line communicates with the supratrochlear foramen but NOT the joint/articular surfacetx: IM pins (Rush or cross), IM pin + plate, 2 plates (best results especially if comminuted), ESF with a full intercondylar pin (modified I)
one humeral condyle—two ossification centersDescribe the fusion times
2 ossification centers fuse by 3 months condyle fuses with metaphysis 5-6 months
most common side (medial or lateral) of humeral condylar fractures
LATERAL –smaller compared to medial with a smaller epicondylar crest–lies lateral to bone axis and receives the majority of weight bearing through the radial headoccurs less often in cats due to absence of a supratrochlear foramen and sizes are approx equal wider and strongerBREED: FRENCH BULLDOGS
lateral condylar fractures in young dogs
peak 4 months age—SH IV(in older dogs consider IOHC)medial aspect of the condyle will palpate DISTALLYrepair–lag screw + antirotational pin, 2 lag screws, lag screw and plate, ESF (modified I), K wires alone in dogs < 4 kg, self compressing pinscan be done closed with fluoroscopic guidance can use cannulated screws
growth plate damage following SH IV fracture
NO decrease in humeral length even with implants across growth plate (may even increase growth–Lefebrve study)do NOT need to remove implantsdistal growth plate is only responsible for 20% growth and closes earlier than proximal growth plate (5-8 months)
use of a metal washer with transcondylar screw
distributes forces more evenly
complications associated with repair of lateral condylar fractures
increase surgery time, increased risk complicationsevery 30 min increased complication risk doubledpresence of intracondylar gap post op associated with risk of implant failure (shear stresses)
approach for a T-Y (intracondylar) fracture
medial and lateral approach +/- osteotomy of olecranon +/- triceps tenotomy (YOUNG DOGS)complications of olecranon osteotomy >37%1. fix condylar portion first, then attach to diaphysis2. fix medial part of humeral condyle then lateral approach for transcondylar screw and stabilization of lateral aspect of condyle
complications follow T-Y fracture repair are most often seen…..
medial aspect–inaccurate repairleads to varus deformity
incomplete ossification of the humeral condyle
medial and lateral ossification center should fuse by 3 months ageif fusion is incomplete–fibrous band and weakened area remainsUK—ESS; US—Cockeroften bilateral
radiographic views to diagnose IOHC
standard CrCd and flexed lateral views of the elbow15 degree craniomedial to caudolateral OBLIQUEother imaging: CT (SP/SN), scintigraphy (not SP)
Marcellin-Little et al reported what finding with conservative treatment of IOHC after diagnosis
43% with partial radiolucent line and 8% with complete radiolucent line fractured within 11 days to 18 months after diagnosisprophy repair–LARGE transcondylar screw (positional vs lag) +/- transcondylar bone tunnels for vascular growth +/- cancellous graft +/- lateral epicondylar plate
T/Fprognosis with traumatic fracture secondary to IOHC is more guarded than true traumatic humeral condylar fracture
TRUEIOHC has more nonunion after repairinfection, seroma common complicationsimplant failure, loss of reduction, nonunion
T/Foutcome of dogs following condylar fracture repair, all show radiographic OA progression but did NOT correlate with force plate gait analysis or fracture reduction
TRUEoutcome of dogs following condylar fracture repair, all show radiographic OA progression but did NOT correlate with force plate gait analysis or fracture reduction
