SCAPULA, SHOULDER, HUMERUS: 49, 50, 51 Flashcards by Charlotte Doyle

name all the muscles that give lateral protection to the scapula

1) omotransversarius
2) supraspinatus
3) infraspinatus
4) deltoideus
5) trapezius
6) triceps
7) teres minor

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name all the muscles that give medial protection to the scapula

1) subscapularis
2) serratus ventralis

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what are the 2 main nerves that crosses the scapula?

A) suprascapular nerve: wraps around the scapular spine
B) axillary nerve: from caudal border of the subscapularis muscle, crosses caudal aspect of scapulohumeral joint

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2 possible classification schemes for scapular fractures

1) anatomic location: body+spine (1), neck (2), glenoid and supraglenoid tuberosity (3)

2) cook for case management: stable extra-articular, unstable extra articular, intra-articular

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what is the possible risk in doing a velpeau sling including the flexed carpus?

risk for flexural contracture

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plate positionin gin relation to the fracture’s location

proximal half -> plate caudally

distal half -> plate cranially

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how to determine if there is a suprascapular nerve injury?

with time atrofia of the supraspinatus and infraspinatus muscles.

cutaneous sensation and distal limb function NOT affected

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most common scapular fractures

cranial glenoid fractures, includind supraglenoid tuberosity (58%)

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possible site for delayed or incomplete union of ossification center in the scapula

caudal glenoid ossification center

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describe the structure and location of the 2 glenohumeral ligaments

1 lateral, 1 medial. the medial one in it’s proximal origin has 2 bands (Y shaped). the lateral band is typically a large single band.

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normal flexion and extension angles for the S-H joint

DOG: 57-165
CAT: 32-164

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what are the stabilizers of the S-H joint?

passive stabilizers: limited joint volume, adhesion-cohesion mechanism, concavity compression, capsuloligamentous restrains

active stabilizers: infraspinatus, supraspinatus, subscapularis, teres minor. to a lesser extent biceps, long head triceps, deloideus and teres major

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optimal entering location for S-H joint arthrocentesis

between great tubercle and acromion

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is mineralization of the periarticular tissues patognomonic of limb desease and limping?

no: 40% dogs wieth mineralization were not lame

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optimal angle for S-H joint arthrodesis

105 to 110°

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how dogs manifest limping if an angle >105-110° has been done for S-H joint arthrodesis?

persistent lameness with mild circumduction

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difference between osteochondritis dissecand and osteochondrosis dissecans

osteochondrosis is a disturbance of normal endochondral ossification, when it progresses in the formation of a cartilage flap is named osteochondritis

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most common and possible site for osteochonodritis dissecans in the S-H joint

caudocentral-caudomedial aspect of the humeral head.

cistic lesions in the glenoid cavity (medial to greater tubercle and adjacent to intertubercular groove) and in the supraglenoid tubercle

age of presentation for OCD of the humeral head

4-8 months

arthroscopic portal placement for cartilage flap removal

lateral port camera, caudolateral portal to remove the flap

surgical removal of OCD flap

1) caudal approach: tissue retraction! but less lose of ROM and quicker recovery in the postoperative period

2) caudolateral interdeltoideus. craniodorsa retraction of infraspinatus, teres minor may help. not necessary to perform a tenotomy of the teres minor. DO NOT separate tendons of insertion of teres minor and infraspinatus, because less exposure than craniodorsal retraction

3) craniolateral approach: tenotomy of infraspinatus tendon. great access to humeral head, less visibility to caudal compartment for fragment removal

other less common deseases of the S-H joint bones

glenoid displasia: toy dogs, 3-10 months of age. misshapen glenoid cavity +- flattened humeral head
MED (multiple epiphyseal dysplasia)
focal humeral head displasia: reported in a barboel

-hypertrophic osteodystrophy of the proximal metaphysis of the humerus

-incomplete ossification opf the caudal glenoid

-chondrocalcinosis (pseudogut), deposition of hydroxiapatite in the joint cartilage. plateau region of humeral head in greyhounds, also in femoral head of german sheperd

bicipital tendinopathy: primary or secondary?

primary: inflammation as a result of overuse or chronic repetitive injury

secondary: in response to other intra-articular desease or cartilaginous loose bodies entrapment beneath the tendon.

what tests cound be performed to diagnosis a bicipital tendinopathy?

1) biceps tendon test (ENGLISH): digital pressure on the tendon origin while flex shoulder and extend elbow

2) biceps tendon test (GERMAN): only to diagnose a complete rupture, so with flexion of the shoulder can obtain a full extension of the elbow

3) drawer test: direct pressure on the tendon by partially flexing shoulder, stabilizing scapula with one hand and translate humerus cranially with other hand

4) biceps retraction test: grasping tendon insertion on cranial elbow, pulling it caudally with the dog in weight bearing stance

medical treatement of bicipital tendinopathy

1-2 injections of long-acting corticosteroid (methyprednisolone acetate 10 to 40 mg), followed by strict cage rest and gradual activity at first NSAID and rest can be attempted

other than bicipital tendinopathy, what else can affect the bicipital tendon?

1) medial displacement of the tendon of origin of the biceps brachii muscle. surgical correction by primary repair of humeral retinaculum +- augmentation. VLP sling 1 week 2) rupture of the tendon of origin of the biceps brachii muscle. may represent a subset of bicipital tendinopathy 3) calcifying tendinopathy of the tendon of biceps brachii muscle. infrequent. hypoxia may trigger remodeling of the tendon collagen into fibrocartilage, followed by condrocyte mediated osteogenesis. skyline is necessary do distinghuish from mineralizations of the tendon from those occurring in the supraspinatus muscle

supraspinatus tendinopathy and muscle contracture

causes of dystrophic calcification is unknown. muscle contraction can be related to trauma and vWD. mineralization in the medial tendon adjacent to the biceps tendon could be relevant, whereas in other areas may be inconsequential.

shoulder instability/subluxation

usually medial (80%), unilateral, toy dogs. diagnosis made with shoulder joint abduction angles test. (30° normal, 50° pathologic)

shoulder subluxation surgical treatment

1) transposition of the tendon of origin of the biceps brachii muscle 2) augmentation of the existing medial collateral ligament: synthetic heavy suture or nilon on medial side of humerus and scapula 3) imbrication of the tendon of subscapularis muscle 4) RITM (radiofrequency-induced thermal modification) trasposition can affect joint balance and lead to osteoarthritis. augmentation does not alter shoulder anatomy.

traumatic luxation of the shoulder, characteristics

usually determine lateral luxation. usually conservative treatement is adequate if reduced soon and stabilied with a velpeau sling for at leat 2 weeks.

main nerves of the humerus and their location

MEDIAL: CAUD TO CRAN: caudal cutaneous antebrachial, ulnar, median, muscolocutaneous LATERAL: radial nerve (most vulnerable in the distal portion of the humerus where it passes cranio lateral.

difference in the distal humerus between cat and dog

cat does not have a supratrochlear foramen but have a supracondylar foramen (proximal to medial epicondyle), through wich passes median nerve and brachial artery

proximal humerus: time to phiseal closure and most common S-H type fractures

7,5-12 M DOG 19-26 M CAT S-H type 1/2 most common

how are fractures entering the supratrochlear foramen classified?

supracondylar fractures fractures of the distal part of the diaphysis do not communicate with the supratrochlear foramen!

how to place a cerclage on the humeral shaft and what should be kept in mind?

diaphysis is thinner in the middle and bigger at the ends, so cerclage will tend to slide distally when placed proximally and viceversa.

optimal pin diameter for intramedullary pin insertion in the humerus

36-45% of craniocaudal medullary canal measured at distal 80% of the humeral length

optimal distal location for intramedullary pin

should be directed in to the medial epicondyle medullary canal. in cats usually there isn't enough space so could be directed in the area proximal to the supratrochlear foramen (only if there aren't fractures of the distal humerus)

where to pay attention in pin insertion in the supracondylar region

DOG: radial nerve laterally CAT: median nerve and brachial artery on the medially placed supracondylar foramen

more common site to fracture in the distal humeral condyle and type of fracutures

lateral side usually are S-H 3/4

is it necessary to remove the implants to guarantee a homogeneous bone growth in the distal phisis?

it doesn't seem necessary because even if the implant crosses the growth plate there isn't a shortened humerus

possible additional implants other than transcondylar lag screw

bone plate, single screw, antirotational pin

sequence of operation when appiying a bilateral plate for T-Y intracondylar fractures

1) medial part of the humerus stabilizet to he diaphysis 2) reposition dog in lateral recumbency and stabilize lateral part of the humerus with a lag screw 3) place the lateral plate most common complication occurred by placing the medial aspect of the condyle in a varus position

phisiologic time to humeral condyle centers of ossifications closure

8-12 weeks

percentage of correlated FCP in dogs with HIF/IOHC

23,5/25%