The shoulder Flashcards
On which side is the labrum of the glenoid widest?
Lateral. Extends the surface area of the glenoid by 25-30%
What holds the biceps tendon in place in the intertubercular groove?
Transverse humeral retinaculum
Is the tendon of the biceps intra or extraarticular?
Intraarticular (craniomedial aspect is surrounded by joint capsule)
What shape is the medial glenohumeral (collateral) ligament of the shoulder?
Y-shaped
What are the rotator cuff muscles of the shoulders?
Supraspinatous, infrapinatous, teres minor (lateral), subscapularis, coracobrachialis (medial). Tendons are blended with the joint capsule
What are normal flexion and extension values of the shoulder in the dog and cat?
Dog: 57 degrees flexion, 165 extension
Cat: 32 degrees flexion, 164 extension
What are the passive mechanisms of shoulder joint stabilization?
Limited joint volume, adhesion/cohesion mechanisms, concavity compression, capsuloligamentous restraints
What are some diagnostics that can be performed in the work-up of shoulder disease?
Physical/orthopedic examination, arthrocentesis, radiography +/- contrast arthrography, CT, MRI, ultrasound (cannot identify medial soft tissue structures of the shoulder).
Are mineralizations of the tendon of origin of the biceps and tendon of the supraspinatous identified on CT always pathologic?
No - identified in 40% of non-lame patients.
What are the active mechanisms of shoulder joint stabilization?
Rotator cuff muscles
What soft tissue structures of the shoulder cannot be visualized on CT?
Teres minor muscle tendon and coracobrachialis muscle
What nerve needs to be protected during excision arthroplasty of the glenoid?
Suprascapular
What are potential fixation methods for shoulder arthrodesis?
Small dogs and cats: transarticular screw, K-wires.
Medium or large dogs: single or double plate fixation (locking plates [SOP, reconstruction, LCP] ideal).
Plating is preferred in all patients for stability.
What shoulder joint angle is ideal following arthrodesis?
105-110 degrees
How far should plating extend on the scapula and humerus during shoulder arthrodesis?
Distal half of the scapula to the proximal half of the humerus (4-5 screws in each bone).
What is the outcome for dogs undergoing shoulder arthrodesis?
Good to excellent. Mild circumduction may result if arthrodesis angles of >110 degrees.
What is the most common location of shoulder OCD?
Caudocentral or caudomedial humeral hdead
What percentage of dogs have bilateral shoulder OCD lesions?
27-68%
Large or giant breed male dogs are most frequently affected. Usually present between 4-8 months of age.
In what percentage of dogs with shoulder OCD is a non-mineralized cartilage flap trapped in the tendon sheath of the biceps brachii muscle?
10%. MRI or arthrography may be required to identify the lesion in these instances.
What is the treatment for OCD of the humeral head?
Debridement of the subchondral defect to bleeding subchondral bone using a bone curette or motorized shaver.
Edges of the defect should not be bevelled to decrease the risk of fibrillation and erosion of the cartilage on the corresponding surface of the glenoid.
Alternative to debridement is the use of OATS (osteochondral autograft transfer system).
What approaches to the shoulder can be performed for removal of OCD lesions?
- Arthroscopy
- Caudal (less loss of shoulder range-of-motion)
- Caudolateral (cranial retraction of the teres minor and infraspinatous, better protection of the axillary nerve).
- Craniolateral (tenotomy of the infraspinatous). Greater exposure of the caudal aspect of the humeral head but limits access to the caudal compartment.
What is glenoid dysplasia?
Hypoplasia or dysplasia of the glenoid resulting in a grossly abnormal articulation of the shoulder joint.
What age is glenoid dysplasia typically diagnosed?
3-10 months of age. History of no or mild trauma.
Affected animals typically hold the elbow flexed and in adduction with the distal limb abducted.
What is the recommended treatment for glenoid dysplasia?
Excision arthroplasty or arthrodesis
What is the imaging diagnosis?
Multiple epiphyseal dyplasia. Genetic disease characterized by defect in ossification of the epiphyses. Normally evident by 8-weeks. Euthanasia typically results.
What is the imaging diagnosis?
Incomplete ossification of the caudal glenoid. Can result in lameness if mobile. Arthroscopic removal is curative.
What is chondrocalcinosis?
Deposition of hydroxyapatite in the articular cartilage. Lesions may be a single spot or small multifocal areas of chondrocyte mineralization.
Clinical relevance is unknown.
What diagnostics should be considered in the work-up for shoulder disorders?
Orthopedic examination, arthrocentesis, radiography (+/- arthrography), CT (+/- arthrography), ultrasonography, MRI
What percentage of dogs have mineralization of the periarticular structures of the shoulder without associated thoracic limb lameness?
40%
Is ultrasonography useful in analysis of the lateral or medial structures of the shoulder joint?
Lateral. Cannot properly visualize medial structures.
What nerve needs to be protected during glenoid excision?
Suprascapular nerve
What surgical options are there for shoulder arthrodesis in small and large breed dogs?
Small dogs: transarticular screw, diverging K-wires, plates and screws.
Large dogs: plates and screws
True or false? Placement of an additional caudal plate may help to prevent implant failure with shoulder arthrodesis?
True
What is the prognosis for patients following shoulder arthrodesis?
Typically good. If the arthrodesis angle is greater than 105-110 degrees may have persistent lameness with mild circumduction of the leg.
What percentage of dogs with OCD have bilateral lesions?
27-68%.
Are female or male dogs more likely to have shoulder OCD?
Large or giant breed male dogs
When debriding an OCD lesion of the shoulder, should the edges of the lesion be bevelled?
No - will cause increased risk of fibrillation and erosion of the corresponding surface of the glenoid.
What surgical approaches to the shoulder joint have been described for OCD removal? What are the benefits of each?
Caudal: improved weight bearing post-op.
Caudolateral: helps protect the axillary nerve and caudal circumflex humeral artery.
Craniolateral (with tenotomy of the infraspinatus tendon): greater exposure of the caudal aspect of the humeral head. Limits exposure to the caudal compartment.
Is glenoid dysplasia usually unilateral or bilateral?
Unilateral. Typically diagnosed in dogs between 3-10 months of age.
What is multiple epiphyseal dysplasia?
Genetic condition of a defect in ossification of the epiphysis of long bones, vertebrae, cuboidal bones and apophysis. Euthanasia is generally recommended.
List 5 conditions that can affect the osseous components of the shoulder?
OCD, glenoid dysplasia, hypertrophic osteodystrophy, epiphyseal dysplasia, incomplete ossification of the caudal glenoid, chrondrocalcinosis.
Is caudal ossification of the caudal glenoid associated with clinical signs of shoulder pain?
Normally asymptomatic, but can display pain if mobile. If painful should remove.
What is chrondrocalcinosis?
Deposits of hydroxyapatite in the articular cartilage. Typically unilateral but can be bilateral. Clinical relevance is unknown.
List 8 conditions that might affect the soft tissues of the shoulder joint.
- Biceps brachii tendinopathy.
- Medial displacement of the biceps tendon.
- Rupture of the biceps tendon.
- Calcifying tendinopathy of the biceps tendon.
- Supraspinatous tendinopathy.
- Medial shoulder instability
- Traumatic shoulder luxation
- Muscle strain
- Teres minor myopathy
- Infraspinatous and supraspinatous muscle contracture
- Villonodular synovitis
- Synovial chrondrometaplasia
- Infraspinatous bursal ossification
- Calcinosis circumscripta
What are the suspected causes of primary and secondary biceps tendinopathy?
Primary: overuse or chronic repetitive injury.
Secondary: in response to intra-articular disease or cartilaginous loose body entrapment.
What is the typical signalment for patients with biceps tendinopathy?
Middle aged medium to large breed dogs
Is lameness associated with biceps brachii tendinopathy typically non-responsive to NSAIDs?
Yes. Typically becomes worse following exercise.
What orthopedic tests can be performed when testing for biceps tendinopathy?
Biceps tendon test, drawer test, biceps retraction test
What imaging techniques can be used for diagnosis of biceps tendinopathy?
Radiography (include skyline view) +/- arthrography, ultrasound, MRI.
What does medical management of biceps tendinopathy typically entail?
Strict rest for 4-6 weeks and 1-2 intra-articular injections of corticosteroids (methylprednisolone [10-40 mg] or triamcinolone).
The duration of action of triamcinolone is not as long as for methylprednisolone, which may reduce deleterious effects on the cartilage.
What are the two surgical options for treatment of biceps brachii tendinopathy?
Tenodesis (via craniolateral approach to the shoulder) or tenotomy (arthroscopic).
What causes medial displacement of the biceps tendon?
Rupture of the transverse humeral retinaculum
How is medial displacement of the biceps brachii tendon diagnosed?
Palpation (medial displacement). Radiographs and ultrasound are typically normal (although arthrography shows poor delineation of the tendon within the intertubercular groove).
What are the surgical treatment options for medial displacement of the biceps tendon?
Reconstruction of the transverse humeral retinaculum +/- augmentation with screws and PDS sutures, or staples and polypropylene mesh.
Prognosis is excellent.
What types of rupture of the biceps tendon can occur?
Traumatic laceration, avulsion from the supraglenoid tubercle or intrasubstance tear.
An irregular margin of the supraglenoid tubercle, calcification within the intertubercular groove, and general signs of osteoarthritis in the shoulder may be radiographically evident.
Arthrography reveals filling defects.
Ultrasound shows inhomogenous hyperechoic areas in the region of the tendon’s origin.
What is the surgical treatment for rupture of the tendon of origin of the biceps brachii muscle?
Tenodesis
What is the proposed pathogenesis of mineralization with calcifying tendinopathy of the biceps tendon?
Injury to the tendon results in hypoxia, this causes remodeling of tendon collagen into fibrocartilage, followed by chondrocyte mediated osteogenesis.
What is the typical signalment of a patient with calcifying tendinopathy of the biceps tendon?
Large breed, middle aged and active dogs. Labradors and Rottweilers are overrepresented.
What are the treatment options for calcifying tendinopathy of the biceps tendon?
Medical and surgical options are the same as for non-calcifying biceps brachii tendinopathy.
What is supraspinatous tendinopathy?
Tendinopathy of the supraspinatous tendon with or without calcification. Contracture may be the end-stage result of this disease process.
Most common in Rottweilers and Labradors.
Which two dog breeds appear predisposed to supraspinatous tendinopathy?
Labrador retrievers and Rottweilers
What is the surgical treatment for supraspinatous tendinopathy
Excision of any calcified tissue within the tendon and associated muscle. Removal of mineralization impinging on the biceps tendon is particularly important.
Medical management consists of NSAIDs and rest.
Is medial instability/subluxation of the shoulder joint considered a congenital condition in large or small breed dogs?
It is considered a congenital soft tissue laxity in small breed dogs (generally diagnosed between 3-10 months of age).
In large dogs it is usually considered an overuse injury.
In both cases the bony anatomy is normal (as opposed to glenoid dysplasia).
How do patients with medial shoulder instability tend to hold the limb?
Flexion and adduction of the elbow joint with abduction of the distal limb.
What is the most common direction of shoulder joint instability?
Medial.
What are the proposed mechanisms of medial joint instability?
Loss of concavity compression, disruption of glenohumeral balance (dynamic muscle imbalance, abnormal angulation of the glenoid, disruption of the capsuloligamentous restraints)
Is shoulder joint subluxation more common in large or small breed dogs?
Large breed, middle-aged, male dogs.
Typically minimally responsive to NSAIDs.
What percentage of shoulder joint subluxations are medial?
80%
What are normal shoulder joint abduction angles?
30 degrees. 50 degrees was the average in clinically affected dogs with medial shoulder instability.
What diagnostic imaging modalities may be useful in the diagnosis of medial shoulder instability?
Stressed radiographs (signs of shoulder joint degeneration in the absence of OCD is typically associated with shoulder instability), MRI, arthroscopy (erosion of the articular cartilage of the caudal humeral head most common).
Ultrasound is not typically able to identify the structures of the medial shoulder joint.
What are the surgical options for surgical stabilization of medial shoulder instability?
- Transposition of the tendon of origin of the biceps or supraspinatous tendon (may change the biomechanics of the joint).
- Augmentation of the existing medial collateral ligament (screw and washers, bone anchors, bone tunnels).
- Imbrication of the tendon of the subscapularis muscle (best for mild degrees of shoulder instability when the tendon is intact and the medial joint capsule is only mildly stretched).
- Radiofrequency induced thermal modification (thermal capsulorrhaphy). Should only be used if the biceps brachii, articular cartilage, and lateral compartment are normal.
- Excision arthoplasty or arthrodesis.
What are the major disadvantages associated with thermal capsulorrhaphy for treatment of medial shoulder instability?
Thermal damage to the glenohumeral ligament, axillary neuropathy, Velpeau bandage complications, carpal stiffness, difficulties in applying thermal energy consistently and uniformly, tendency of the collagen to stretch back to its original size, limited number of appropriate candidates (should not have other shoulder pathology).
What is the long term outcome of patients with medial glenohumeral instability treated with radiofrequency induced thermal modification?
Largely unknown. Due to eventual stretching of the capsule back to its original size has been largely abandoned in people.
Is traumatic medial or lateral shoulder luxation more common?
Medial, although lateral luxation reported frequently in large breed dogs.
Dogs with lateral luxation hold the distal limb in adduction.
Should a Velpeau sling be placed following closed reduction of both medial and lateral shoulder luxations?
No - only medial. Want to prevent adduction of the limb following lateral luxation, therefore a spica or neutral sling are more appropriate.
How is surgical correction of a traumatic shoulder luxation achieved?
Typically with reconstruction or augmentation of the glenohumeral ligament and joint capsule.
Salvage procedures such as arthrodesis and excision arthroplasty can also be considered.
Transposition of the biceps and supraspinatous tendons have been described but result in greater degenerative joint disease, and are therefore not preferred.
Is the prognosis for traumatic shoulder luxation typically good or bad?
Good
When muscle is strained to 80% of failure, the strength of the muscle contraction is decreased by how much immediately after injury?
30%, then 50% by 24 hours, 25% by 48 hours, returning to 90% by 1 week
How are muscle strains diagnosed?
Ultrasound, MRI.
What is the treatment for muscle strains?
Grade 1-3: conservative management.
Grade 4 (complete disruption of the muscle): surgical repair may be required.
How does teres minor contracture differ from infraspinatous and supraspinatous contracture?
Pain is a major feature
What is the treatment for teres minor contracture?
Surgical excision of the entire muscle. Full function is usually restored.
Does contracture of the supraspinatous or infraspinatous muscle occur more frequently?
Infraspinatous
What is the typical signalment of patients with infraspinatous muscle contracture?
Medium to large breeds (Brittany spaniels, pointers, labradors), active and middle aged with no apparent sex predilection.
What is a common clinical presentation for dogs with infraspinatous or supraspinatous contracture?
Biphasic history (acute painful lameness followed by a chronic, static nonpainful gait abnormality).
How is infraspinatous muscle contracture diagnosed?
Ultrasound +/- MRI.
Clinically the patient holds the elbow in adduction and flexion throughout the gait, with circumduction of the limb and a carpal flip. The antebrachium is externally rotated.
What is the treatment for infraspinatous muscle contracture?
Tenotomy. Restores the gait to near normal.
If early in the disease process a fasciotomy may be performed to relieve potential compartment disease and allow muscle reperfusion.
What is villondular synovitis?
Rare disease affecting middle aged to older large breed dogs.
Often associated with a severe lameness.
Synovial fluid is orange to red and there is yellow discoloration of the synovium, capsular hemorrhage, hemorrhagic nodules, and prominent soft tissue masses on arthroscopy.
What is the surgical treatment for villonodular synovitis?
Excision arthroplasty or arthrodesis. Can attempt medical management prior with NSAIDs.
What is the typical signalment of dogs with synovial chondrometaplasia (synovial osteochondromatosis)?
Medium to large breed, no sex predilection. Chronic low grade lameness is the most common clinical sign.
It is a proliferative disease of undifferentiated stem cells. Can be primary (in a normal joint), or secondary (following traumatic, degenerative, or inflammatory joint disorders).
What surgical treatment has been reported for synovial chrondrometaplasia?
Debridement of nodules, loose body removal, synovial stripping. Excision arthroplasty or arthrodesis may be required in severe cases.
In which dog breed has infraspinatus bursal ossification been reported?
Labrador retrievers.
Radiographs demonstrate mineralizations (osteochondromatosis) of the infraspinatus bursa.
What is the surgical treatment for infraspinatus bursal ossification?
Surgical excision of loose bodies, the infraspinatus bursa, and a portion of the tendon of the infraspinatus muscle.
Medical management can be attempted with rest, NSAIDs, and intra-articular long acting steroids.
What is the treatment for calcinosis cutis of the soft tissue structures of the shoulder?
Corticosteroids and disodium etridonate.
Surgical excision is typically unrewarding due to the dystrophic cause of the disease.
According to Phipps 2022 in Vet Surg, what was the outcome of shoulder arthrodesis using 2 locking plates? What was the mean symmetry index post-operative?
Outcome was good (11/12 dogs made a full functional recovery). Mean symmetry index was 8% during gait analysis.
In a study by Zann 2022 in Vet Surg, what was the decrease in load to the operated limb 12-months following surgical debridement of proximal humeral OCD? Was brachial circumference and the progression of osteoarthritis affected?
4%.
Brachial circumference was decreased in the operated limb, and there was progression of OA as determined by radiographs and CT.
In a study by Carwardine 2019 in JSAP, what technique was used for repair of both lateral and medial shoulder instability in a feline cadaveric study?
Ligament prosthesis using bone tunnels and 3.5 metric polypropylene
In a study by Hammer 2021 in JSAP, what surgical technique was used to stabilize instances of canine medial shoulder instability without post-operative external coaptation?
An inverted V-shaped extracapsular stabilization technique. All 6 cases had acceptable outcome.
What technique described by Livet 2019 in VCOT, may be useful in detecting dogs with medial glenohumeral ligament instability?
Stressed radiographic views of the shoulder
What approach for minimally invasive treatment of shoulder OCD in dogs was described by Vezzoni 2021 in VCOT?
The modified cheli approach
Describe the modified cheli approach to the shoulder joint from the study by Vezzoni 2021 in VCOT.
What technique was described by Llido 2023 in VCOT in canine cadavers for treatment of medial glenohumeral instability?
Arthroscopically guided prosthetic ligament. Abduction angles after repair were not significant different from intact.
What structures of the shoulder are delineated in the image from Holman 2024 in VCOT? What percentage of these structures could be seen via a lateral arthroscopic approach?
Medial glenohumeral ligament: 58%
Subscapularis tendon: 20%
What structure of the shoulder is delineated in the image from Holman 2024 in VCOT? What percentage of this structure could be seen via a lateral arthroscopic approach?
Biceps tendon: 48% at a standing angle, 63% when flexed.
In a study by Gemignani 2022 in VRU, was ultrasound able to successfully identify transection of the medial glenohumeral ligament in cadavers? What finding was discriminatory to transection of the medial glenohumeral ligament?
No - ultrasound was not able to identify transection of the ligament.
An articular space wider than 8.2mm was discriminatory for transection.
