SCAPULA, SHOULDER, HUMERUS: 49, 50, 51 Flashcards
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
name all the muscles that give medial protection to the scapula
1) subscapularis
2) serratus ventralis
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
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
what is the possible risk in doing a velpeau sling including the flexed carpus?
risk for flexural contracture
plate positionin gin relation to the fracture’s location
proximal half -> plate caudally
distal half -> plate cranially
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
most common scapular fractures
cranial glenoid fractures, includind supraglenoid tuberosity (58%)
possible site for delayed or incomplete union of ossification center in the scapula
caudal glenoid ossification center
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.
normal flexion and extension angles for the S-H joint
DOG: 57-165
CAT: 32-164
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
optimal entering location for S-H joint arthrocentesis
between great tubercle and acromion
is mineralization of the periarticular tissues patognomonic of limb desease and limping?
no: 40% dogs wieth mineralization were not lame
optimal angle for S-H joint arthrodesis
105 to 110°
how dogs manifest limping if an angle >105-110° has been done for S-H joint arthrodesis?
persistent lameness with mild circumduction
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
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%
