Ch 50 - The shoulder Flashcards
At what age do the glenoid and proximal humeral physes fuse?
Glenoid - by 6mo
Proximal humerus - by 12mo
What is the ratio of glenoid to humeral head ratio?
1:2.5
What are the three zones of the labrum?
- Transitional zone (collagen fibers in a fishnet-like pattern)
- Circular fiber zone
- Meniscal fold
The labrum is highly vascularised (except along the free margin) and is loosely attached to the glenoid
How thick is the hyaline cartilage of the shoulder joint?
approx 1mm in 20-25kg dogs
What shape are the collateral ligaments of the shoulder?
- Medial glenohumeral ligament is Y-shaped
- Lateral glenohumeral ligament is a thick band
What structure function to keep the tendon of the origin of the biceps brachii within the intertubercular groove?
Transverse humeral retinaculum
What are the normal flexion and extension angles of the shoulder in the dog and cat?
Dog
- extension 165
- flexion 57
Cat
- extension 164
- flexion 32
List the passive mechanisms of shoulder stability
- Limited joint volume
- Adhesion/cohesion mechanism
- Concavity compression
- Capsuloligamentous restraints
What are the main active stabilisers of the shoulder?
- Supraspinatus
- Infraspinatus
- Teres minor
- Subscapularis
And to a lesser extent:
- Biceps brachii
- Long head of the triceps
- Deltoideus
- Teres major
What type of mechanoreceptors are within the collateral ligaments?
What is their function?
- Type I, II and III mechanoreceptors
- Type I (Ruffini) are the most common
- Allow ligaments to work as sensory structures to actively contribute to shoulder stability via reflex arcs with the associated musculature
What is the optimum concentration of iodine for arthrography when VT angiography is performed?
60mg/ml
What percentage of shoulder pathology is extra-articular and therefore would be missed on arthroscopy?
15%
What is the recommended angle for excision arthroplasty of the glenoid?
- Distolateral to proximomedial osteotomy of the scapular neck
- Being careful to protect the suprascapular nerve
What is the outcome of excisional arthroplasty?
- Good-to-excellent in small dogs
- Unknown in large breeds
What angle of shoulder is aimed for in arthrodesis?
What landmark should be used for the rotation alignment?
- 105-110 degrees
- The greater tubercle should be positioned craniodistal to the acromion and slightly medial in the sagittal plane
What is the reported outcome after shoulder arthrodesis?
- Good-to-excellent
- Normal or near-normal gait in 12 weeks
What is the most common location of shoulder OCD?
How often is this disease bilateral?
- caudocentral or caudomedial aspect of the humeral head, usually opposite the caudoventral rim of the glenoid
- 27-68% bilateral
What percentage of OCD cases will have a nonmineralised cartilage flap trapped within the tendon sheath of the biceps?
Approx 10%
What are the approach options of debridement of a shoulder OCD flap?
Caudal
- requires assistant for retraction
- results in less loss of RoM and improve weight bearing in first month
Caudolateral interdeltoideus approach
- Craniodorsal retraction of infraspinatus and teres minor
- Better protection of caudal circumflex humeral artery and axillary nerve
Craniolateral
- Included tenotomy of infraspinatus tendon
- Greater exposure of caudal aspect of humeral head but limits access to caudal joint pouch
What is glenoid dysplasia?
What breeds are predisposed?
What does it cause?
What is the treatment?
- Glenoid dysplasia is hypoplasia or aplasia of the glenoid resulting in grossly abnormal articulation
- Toy breeds (Toy and Min poodle, Chihuahua, Pom, Sheltieetc)
- Results in medial luxation of the shoulder
- Tx: Arthrodesis or excision arthroplasty with an acceptable return to function
What is multiple epiphyseal dysplasia?
What is the treatment?
- A rare defect in the ossification of the epiphyses of long bones, vertebrae, cuboidal bones and apophyses
- Severe lameness, resembles bony changes seen with congenital hypothyroidism
- Tx: euthanasia
In what breed has focal humeral head dysplasia been reported?
Boerboel (Arthrodesis)
What is the radiographic hallmark of Hypertrophic Osteodystrophy?
“Double physis” - irregular radiolucent line in the metaphysis, parallel to and seperate from the physis
What is this disease?
Is it clinically significant?
Incomplete ossification of the caudal glenoid
- Often asymptomatic but can be a cause of lameness if mobile
- Arthroscopy to comfirm if mobile and can remove the fragment
What is chondrocalcinosis?
What breeds are overrepresented?
What gross lesions are seen?
Is it clinically significant?
- Chondrocalcinosis is deposition of hydroxyapatite in the articular cratilage, “pseudogout”
- Overrepresented in the Greyhound and GSD
- Gross lesions: small pits in cartilage surface, scarring, scoring and cracking, often unilateral
- Often found incidentally at necropsy, clinical significance unknown
What disease process is shown in the following radiograph?
Multiple epiphyseal dysplasia (note the severely irregular and misshapen humeral head)
Lists tests which can be done to test for biceps tendinopathy
- Biceps tendon test
- Drawer test - Places direct pressure against the tendon and associated sheath (doe not test for tearing/rupture)
- Biceps retraction test - Grasping the tendon of insertion at cranial elbow and pulling caudally whilst weight-bearing
All tests are assessing for a pain response
What are the surgical options for biceps tendinopathy?
- Tenodesis
- Tenotomy (using hooded arthroscope knife or bipolar). Further studies needed to asses if joint stability is effected
What breeds are predisposed to medial displacement of the biceps tendon of origin?
What are the surgial options?
- Greyhounds, Afghan hounds, GSD, Border Collies
- Primary reconstruction of the transverse humeral retinaculum and/or augmentation with screws and PDS or staples and polypropylene mesh
- Prognosis excellent
What breeds are predisponsed to calcification of the biceps tendon of origin?
Labs and Rottweilers
What is the surgical treatment of supraspinatus tendinopathy?
Excision of calcified tissue (controversial if medical vs surgical treatment is best)
What is the most common direction of shoulder luxation?
Medial (approx 80%)
What is the normal shoulder abduction angle
Approx 30 degrees (vs 50 with instability)
What treatment options are available for stabilisation of the shoulder joint?
- Transposition of the tendon of origin of the biceps or supraspinatus (84.5% good to excellent outcome)
- Augmentation of medial collateral with suture (better than transposition)
- Imbrication of tendon of subscapularis muscle
- Radiofrequency induced thermal modification (RITM)
- Excision arthroplasty
- Arthrodesis (85.7% good to excellent)
Transposition techniques result in altered biomechanics, incongruency and OA. Placement of heavy synthetic suture preferred method in a V-shaped manner with screw and washer bone tunnels or anchours
What coaptation is used for closed reduction of traumatic shoulder luxation?
Velpeau
What is the range of grades of muscle strain injury?
Grade 1 = minimal tearing of individual muscle fibres
up to Grade 4 = Complete muscle rupture requiring debridement and repair
What are some clinical features of teres minor myopathy?
Treatment of choice?
- Prominent pain with reduced shoulder flexion
- Tx: excision of entire muscle, excellent prognosis
What breeds are predisposed to infraspinatus contracture?
What is meant by a biphasic history?
What are some characteristic gait features?
- Brittany spaniel, Pointers, Labs
Biphasic
- Acute painful pain, swelling and lameness
- Chronic, static, nonpainful gait abnormality
Gait
- elbow adduction, shoulder abduction
- external rotation of antebrachium
- circumdution of limb with carpal flip
List the treatment option of villonodular synovitis
- Synovectomy
- Radiation therapy
- anti-TNF-a administration
- excision arthroplasty or arthrodesis
What is the disease seen in the radiograph?
What are the treatment options?
Synovial chondrometaplasia
- a proliferative disorder of undiffernetiated stem cells. Fibroblast-like cells are transformed into chondroblastic cells under the influence of the extracellular chondroid matrix material
Treatment
- Good outcome with debridement of nodules, loose body removal and synovial stripping
- Excision arthroplasty or arthrodesis
