The elbow Flashcards
Label the following parts of the elbow joint.
What are the main functions of the three joints comprising the elbow joint?
Humeroradial: main weight bearing axis.
Humeroulnar: restricts elbow motion to the sagittal plane.
Radioulnar: pronation and supination.
What are the sections of the medial coronoid process?
Base, midbody, apex.
What is the main extensor muscle of the elbow and its innervation?
Triceps brachii (+ tensor fascia antibrachii and anconeus). Innervated by the radial nerve.
What are the main flexors of the elbow joint and their innervation?
Biceps brachii and brachialis muscle, innervated by the musculocutaneous nerve
What are the main ligamentous support structures of the elbow?
Lateral and medial collateral ligaments, annular ligament, interosseous ligament.
What is the normal range of motion of the elbow joint?
130 degrees (36 degrees in flexion, 165 degrees in extension)
Beyond how many degrees of elbow extension does the anconeal process articulate with the olecranon fossa, restricting movement in the sagittal plane?
90 degrees
When the elbow is at 135 degrees of extension what structures are the primary stabilizers in pronation and supination?
Pronation: Anconeal process
Supination: Lateral collateral (with secondary stabilization from the anconeal process and medial collateral)
When the elbow is held at 90 degrees what structures are primarily responsible for rotational stability?
Medial collateral ligaments
What is the name of the test that examines the integrity of the medial collateral ligaments?
Campbell’s test.
What are the normal values of elbow supination and pronation as determined by the Campbell’s test?
Supination: 17 - 50 degrees laterally
Pronation: 31 - 70 degrees medially
Luxation of the elbow can only occur if the elbow is flexed beyond how many degrees?
45 degrees
What percentage of traumatic elbow luxations are lateral?
92 - 100%
What are the reasons that lateral traumatic elbow luxation is more frequent than medial?
Large size of the humeral trochlear, inherent weakness of the medial (compared to lateral) collateral
In what percentage of cases is collateral ligament damage reported in conjunction with traumatic elbow luxation?
18 - 50%.
One collateral ligament has to be ruptured for elbow luxation to occur in the dog, both collaterals have to be ruptured in the cat.
How does a patient with traumatic elbow luxation typically carry the affected limb?
Abduction and external rotation of the antebrachium, slight elbow joint flexion.
In what percentage of cases of traumatic elbow luxation does the anconeal process remain within the olecranon fossa?
16%
When is closed reduction of elbow luxation contraindicated?
Concurrent intra-articular or periarticular fracture
How is closed reduction of the elbow performed?
Flex the elbow to 90 degrees and internally rotate and abduct the antebrachium to engage the anconeal process in the olecranon fossa.
Once the anconeal process is engaged extend the elbow joint and adduct and internally rotate the antebrachium.
How can elbow stability be assessed following closed reduction of a luxation?
Stressed radiographs, Campbell’s test (should be compared to the contralateral elbow).
What are some indications for open surgical reduction and stabilization of traumatic elbow luxation?
Avulsion fracture at the site of collateral ligament attachment, fracture involving the articular surface, intra-articular apposition of soft tissues, marked instability or reluxation after closed reduction, and chronic luxation
From what approach is open reduction of the elbow joint performed?
Caudolateral.
Name two methods of stabilization of the elbow joint following open reduction.
- Primary ligament repair and augmentation.
- Ligament replacement with synthetic materials (screws and washers, bone anchors, tunnels).
How are avulsion injuries of the collateral ligaments repaired?
Proximal: Bone tunnels in the humeral epicondyle, or anchored with screws and spiked washers, or bone anchors.
Distal: Sutured to the annular ligament and surrounding fibrous tissues.
Avulsion fractures: lag screw, tension band device (if of sufficient size).
What post-operative management is recommended following surgical repair of an elbow luxation?
Splint or external fixation (applied through the distal humerus and proximal olecranon).
Flexible ESF fixation using rubber bands may reduce sequelae associated with prolonged immobilization, including; decreased synovial fluid production, cartilage stiffness/thickness, osteoarthritis and loss of muscle mass and bone mineral content. Elbow is fixed at 140 degrees.
What is the outcome following closed or open elbow reduction?
Good to excellent. Most likely complication is osteoarthritis.
What are the types of congenital elbow luxation?
Type 1: Humeroradial: lateral luxation of the radial head. Most common in young, large breed puppies.
Type 2: humeroulnar: lateral rotation of the ulna with subluxation/luxation. Primarily associated with small breed dogs at a young age.
Type 3: Combined humeroulnar and humeroradial. Luxation of the radius and ulna. No breed predisposition but often associated with generalized joint laxity and multiple congenital skeletal deformities.
What condition is shown?
What condition is shown?
What are the clinical signs associated with type I humeroradial luxation?
Supination of the antebrachium, valgus deformity at the carpus, mild lameness. Radial head is palpated lateral to the joint.
What are treatment options for type I humeroradial luxation?
- Conservative management if mild (or delaying treatment until skeletal maturity, although correction prior to 5-months results in improved results).
- Surgical open reduction. May require osteotomy or ostectomy to facilitate in some cases. Stabilization of the joint is facilitated by reconstruction of the lateral collateral ligament and joint capsule. A transarticular screw or radioulnar (care in juvenile animals with considerable remaining growth potential) screw may also aid in maintenance of reduction. An ESF technique based on the CORA has also been used by Fox - radius/ulna chapter).
- Radial head ostectomy (associated with a poor outcome).
- Arthrodesis (marked gait abnormality).
Describe the novel treatment technique for type I humeroradial luxation as outlined by Fox in the radius/ulna chapter?
What is the typical clinical presentation of type II humeroulnar luxation?
Partial joint flexion and internal rotation of the antebrachium. The olecranon is palpated lateral to the humerus.
Males are more frequently affected.
What are the treatment options for type II humeroulnar luxation?
- Closed reduction and immoblization: best in dogs <4 months. Augmented with transarticular pinning or modified ex-fix (as for lateral elbow luxation).
- Open reduction and immobilization: indicated in dogs >4 months or when closed reduction fails. Multiple options for repair including: medial imbrication, transposition of the olecranon medially and distally, ulnar osteotomy and radioulnar synostosis, trochlea and trochlear notch reconstruction, external fixation, and transarticular pins.
What are the components of elbow dysplasia?
- Fragmented coronoid process (most common, >95%).
- Ununited anconeal process.
- Humeral trochlea OCD.
- Joint incongruity.
- Articular cartilage damage.
What percentage of dogs have bilateral involvement of elbow dysplasia?
35%
Which breed of dog is most frequently affected by elbow incongruity?
Bernese mountain dogs (50% of dogs with dysplasia). Golden retrievers frequently affected by OCD (25%).
Is ununited anconeal process more common in male or female dogs?
Male dogs, normally between 5-12 months of age.
Bilateral in 20-35% of cases.
What is positive and negative radioulnar incongruence?
Positive: ulna is longer than the radius (short radius).
Negative: radius is longer than the ulnar (short ulnar).
What are proposed etiologies for ununited anconeal process?
1) presence of a second center of ossification associated with the anconeal process. Negative radioulnar incongruence results in repetitive microtrauma and fracture.
2) decreased radius of the trochlear notch of the ulna resulting in poor articulation between the ulna and humeral condyle.
What is the imaging diagnosis?
At what age can ununited anconeal process be diagnosed?
Typically >20 weeks (fusion occurs at around 20 weeks in German Shepherds).
What surgical treatments are described for ununited anconeal process?
1) Removal (caudolateral approach).
2) Reattachment (dogs < 24 weeks with normally formed trochlear notch).
3) Ulnar osteotomy/ostectomy (most likely to be successful <7 months).
4) Combination of 2 and 3 (93% fusion).
What percentage of dogs were free of lameness following removal of ununited anconeal process?
50%. Owners should be warned of progression of osteoarthritis.
Why is a proximal ulna osteotomy/ectomy recommended for the treatment of ununited anconeal process?
Distal ostectomy/osteotomy did not restore contact patterns, presumably due to an intact interosseous ligament.
Caudal tipping and varus deviation of the proximal ulna can be prevented by oblique osteotomy angle (starting proximo-caudo-lateral and angling disto-cranial-medial at 40-50 degrees).
What breed of dogs are predisposed to flexor enthesopathy (originally termed ununited medial humeral epicondyle)?
Labradors, followed by German Shepherds and English Setters.
Results in pathologic changes within the flexor muscles of the carpi and digits and their attachments on the medial epicondyle.
What are the two forms of flexor enthesopathy?
Primary (15-35%) and secondary to other elbow pathology.
What tests can be used to assess for flexor enthesopathy?
1) pain on 90 degree flexion of the elbow with extension of the carpus.
2) Radiography, ultrasound, CT, MRI +/- arthroscopy.
What are the treatment options for flexor enthesopathy?
Primary: conservative management with intraarticular methylprednisolone, tenotomy or partial excision of the affected flexor tendon may be effective.
Secondary: treatment of the intraarticular lesions +/- local treatment of the muscle (as for primary). Prognosis is more guarded than for primary disease.
Is medial compartment disease of the elbow more common in males or females?
Males. Typical onset between 6-18 months (although biphasic distribution is also reported).
In what percentage of dogs affected by medial coronoid disease is elbow incongruity also present?
60%. Bilateral disease in 25-80% of dogs.
What is the etiology of medial coronoid process disease?
Combination of a delay in endochondral ossification and biomechanical forces during maturation likely initiate cleft formation, fracture, bone remodeling, and ultimately fatigue of the subchondral bone.
What are some postulated mechanical causes of initiation or propagation of medial compartment disease?
1) Abnormal shape the trochlear notch of the ulna.
2) Positive (45% of elbows) or negative (14%) radioulnar incongruence.
3) Dynamic radioulnar translation during ambulation.
4) Supraphysiologic loading of the lateral aspect of the MCP (excessive pronation of the radius and soft tissue laxity, excessive pull of the biceps brachii/brachialis muscle, developmental malformation of the radial incisure).
5) Osseous conformational or ligamentous insufficiency (varus or valgus deformity).
Describe the extended arthroscopic grading scheme for medial compartment lesions of the elbow.
See pages 860-861 for complete description of the grading system.
Describe the modified outerbridge score grading system.
What are the two common types of humeral trochlear cartilage lesions seen in the elbow?
1) OCD of the humeral trochlea.
2) Kissing lesion formed by contact between a FCP and the medial humeral condyle.
What is the synovial fossa of the elbow?
A cartilage free area on the lateral aspect of the trochlear notch (normal finding in a dog).
What is the typical stance for a dog with medial compartment disease?
Manipulation of the elbow in which direction typically causes pain in dogs with medial compartment disease on physical examination?
Flexion of the elbow joint and supination of the distal limb. This increases load in the medial compartment.
Why is mepivacaine preferred over lidocaine or bupivacaine for intra-articular anesthesia?
Less chondrotoxicity.
What is the imaging diagnosis?
Where are osteophytes most frequently located in medial coronoid process disease on radiographs of the elbow?
Osteophytosis of the proximal anconeal process (70%), radial head (37%), and lateral epicondyle (57%) are common. Trocheal notch sclerosis is also a common finding and can be quantified.
Ultimately CT is generally required for definitive diagnosis.
What is the international working group grading system for developmental elbow disease?
How is the extent of subtrochlear sclerosis quantified radiographically?
Radiographs can be used to accurately assess what level of elbow incongruity?
> 2mm (90 degree flexed lateral projection).
What are the most common findings on elbow CT in a patient with medial coronoid process disease?
Sclerosis of the MCP and osteophytes.
Additional findings may include abnormal shape of the MCP, irregularity of the radial incisure, fissure or fragmentation of the MCP, lucencies along the radial incisure.
What is the main disadvantage of CT as compared to arthroscopy in the assessment of medial coronoid process disease?
Cannot assess cartilage lesions.
One benefit of CT is the ability to assess the subchondral bone.
What are the four patterns of medial coronoid shape based on CT scan of the elbow?
How is the duplicated circle superimposition technique performed for assessment of radioulnar incongruence?
Note: A three dimensional sphere fitting technique of the trochlea notch is more accurate than the circle superimposition technique, but is less straightforward to performed (requires 3D rendering of the CT images).
Is MRI or arthroscopy generally considered a more valuable tool for diagnosis of medial compartment disease?
Arthroscopy, as it allows simultaneous diagnosis and treatment.
What size arthroscope is preferred for arthroscopic evaluation of the radioulnar joint?
1.9 mm short 30 degree oblique arthroscope.
What intraarticular pressure is preferred when using a fluid pump during elbow arthroscopy?
70 mmHg
In what position is elbow incongruity best assessed during elbow arthroscopy?
A standing angle of 135 degrees.
Elbow joint flexion, pronation/supination, loading conditions of the joint, and the presence of the arthroscope can all influence incongruity.
What are the surgical approaches for treatment of medial compartment disease?
1) Intermuscular medial approach to the elbow joint (between the flexor carpi radialis and pronator teres muscle) +/- osteotomy of the medial epicondyle or tenotomy of the pronator teres muscle.
2) Arthroscopy
In what percentage of cases having elbow arthroscopy performed was iatrogenic superficial cartilage damage observed?
15%
Conversion to open surgery was required in 5% of cases.
What are some treatment options for OCD of the humeral trochlea?
1) Removal of the cartilage flap followed by;
a) abrasion arthroplasty
b) forage
c) microfracture
d) curettage
2) Osteochondral autogenous transfer system (OATS) (performed from the lateral aspect of the femoral trochlea). Can also perform on cadaveric dogs which allows collection from the same location as the defect (orthotopic transplantation).
3) Synthetic osteochondral transplants (thermoplastic plugs with a titanium base; SynACart).
What are surgical treatment options for medial compartment disease?
- Fragment removal +/- subtotal coronoid ostectomy (starting just caudal to the medial collateral and extending to the caudal extent of the coronoid fissure/fracture). Does not address the underlying cause of the disease and is considered palliative.
- Biceps ulnar release procedure (BURP). Minimal evidence to support use. Proposed to eliminate rotational forces (supination) on the ulnar.
- Osteotomy of the radius to correct for positive radioulnar incongruence. Inconsistent clinical results and difficult to determine degree of radial lengthening required. Newer CERO technique using a specifically designed SOP may alleviate some of these issues but has not been clinically evaluated.
- Static osteotomy of the ulna.
- Dynamic osteotomy of the ulna:
a. Dynamic proximal ulnar osteotomy or ostectomy (DPUO).
b. Segmental osteotomy (in juvenile dogs with positive radioulnar incongruence)
c. Distal dynamic ulnar ostectomy (DDUO). Advocated for 4-6 month old puppies.
d. Bi-oblique dynamic proximal ulnar osteotomy or ostectomy. - Proximal abducting ulnar osteotomy (PAUL).
- Proximal ulnar rotational osteotomy (PURO) (30 degrees external rotation). Not reported clinically.
- Sliding humeral osteotomy (external rotational humeral osteotomy [ERHO] also described but not clinically reported).
- Canine unicompartmental elbow (requires subluxation of the joint).
- Arthodesis.
At what age is osteotomy of the distal part of the ulna considered to still allow adequate axial translation in cases of elbow incongruity?
4-6 months, older than this age reduction in the elasticity of the interosseous ligament is thought to prevent movement.
Why is DDUO performed subperiosteally?
To prevent synostosis between the radius and ulna (performed in dogs 4-6 months of age).
What surgical technique is depicted?
Subtotal coronoidectomy
What surgical technique is depicted?
What surgical technique for the treatment of medial compartment disease is depicted?
Distal dynamic ulnar ostectomy.
What surgical technique for the treatment of medial compartment disease of the elbow is depicted?
Bi-oblique dynamic proximal ulnar osteotomy.
55 degrees caudal to cranial and 48 degrees lateral to medial recommended for correction. Should be performed at the junction of the proximal and middle thirds of the radius.
When performing a dynamic proximal ulna osteotomy, what is the effect on the angle of the proximal ulna?
Caudal tipping and varus deformity generally occurs. This may be more responsible for unloading of the medial compartment than correction of incongruity.
Excessive tipping can be eliminated by use of an IM pin, or dynamic oblique osteotomy.
What is the effect of PAUL on the angle of the ulna?
Leads to abduction, caudal tipping and mild axial rotation, theoretically unloading the medial compartment of the elbow joint.
What reduced the complications associated with a sliding humeral osteotomy?
Use of a stepped plate.
What material is the canine unicompartmental elbow system made of?
Polyethylene plug in the medial coronoid process, and figure-eight cobalt chrome prosthesis in the opposing humeral trochlea.
What are some complications associated with use of the canine unicompartmental elbow?
Avulsion/nonunion of the medial epicondyle, implant malpositioning, incisional/extraarticular infection.
What are the major disadvantages associated with subtotal coronoidectomy of the medial coronoid?
May introduce joint instability and load concentration.
What are some alternative treatment modalities that might be useful in the treatment of medial compartment disease in dogs?
- Stem cells
- Electrostimulated acupuncture
- Joint denervation (technically challenging; non-selective denervation can be achieved using botulinum, capsaicin, or saporin)
- Denervation of the subchondral bone plate has been described using PMMA injected under the subchondral bone but was associated with a high risk of infection.
- Low dose radiation.
What is the outcome associated with treatment of medial compartment disease?
Functional improvement in 85% of cases.
Complications are least frequent with dynamic proximal ulnar osteotomy, followed in increasing order of complication frequency by proximal abducting ulnar osteotomy, canine unicompartmental elbow, and sliding humeral osteotomy.
According to Amadio 2020 in Vet surg what was the effect of PAUL on the mechanical axis of the thoracic limb?
Shifting of the mechanical axis from medial to lateral.
According to Danielski 2021 in Vet Surg, what were the three most common complications associated with PAUL for elbow dyplasia?
Non union, implant failure, infection. Body weight was a risk factor for increased complications.
In a study by Jones 2024 in Vet Surg, what CT finding was positively correlated with the presence of osteoarthritis in labrador retrievers?
Subchondral bone cysts
What treatment is described by von Pfeil 2024 in Vet Surg for correction of too short radius resulting in elbow incongruity?
Arthroscopically assisted ulnar shortening
In a study by Danielski 2023 in JAVMA, what were the most common major and minor complications in dogs following proximal bioblique ulnar osteotomy? What 2 factors were associated with an increased risk of complications?
Most common major complication was non-union, delayed union was the most common minor complication.
Increased risk of complications was observed with increasing age or decreased weight of the patient (mainly chondrodystrophic dogs that had issues).
In a study by Baud 2020 in JSAP, what were the two types of medial coronoid fragmentation described?
Radial incisure or apex fragmentation
In a study by Baud 2020 in JSAP what was the theoretical effect of decreased radioulnar joint space?
Increased risk of radial incisure fragmentation
In a study by Williams 2020 in JSAP what percentage of cats with elbow luxation in which closed reduction was performed suffered reluxation? What was the most common surgical technique performed? What was the outcome?
61% of cats with closed reduction suffered reluxation (risk increased with duration from injury).
Transondylar bone tunnels and circumferential suture were most commonly performed (see image).
The outcome (for both closed and open reduction) was considered excellent.
In a study by McCarthy 2020 in JSAP, what technique was successfully used for elbow arthrodesis? What was a benefit of this technique in terms of approach?
Medial arthrodesis (rather than caudal) was performed using a 2.7/3.5mm pre-contoured elbow arthrodesis plate or SOP. The mean angle of arthrodesis was 118 degrees.
The main benefit in terms of the approach was no requirement for ulnar osteotomy for debridement of the articular surface. There is also a mechanical advantage as the plate is edge-loaded, and the plate can be precontoured to ensure an accurate standing angle.
In a study by Zweifel 2020 in VCOT, what CT slice size was recommended for accurate detection of fragmented MCP?
1mm
In a study by Coghill 2021 in VCOT, was there a difference in outcome between dogs with medial compartment disease of the elbow treated with arthroscopy with fragment removal alone as compared to arthroscopy and PAUL?
No - there was no difference in canine brief pain inventory scores or use of NSAIDs.
Dogs greater than 3 years of age at the time of initial surgery had greater NSAID use and higher pain scores regardless of surgery.
In a study by Jacqmin 2023 in VCOT, what imaging modality was useful in diagnosing MCP disease in unclear cases based on radiography and CT?
Ultrasound - was able to identify joint effusion and abnormal shape to the medial coronoid process.
In a study by Scharpf 2024 in VCOT, did injection of autologous conditioned plasma improve post-operative limb function in patients undergoing subtotal coronoidectomy for MCP disease?
No - there was no change in force plate analysis parameters with the addition of ACP.
While vertical and propulsive parameters gradually improved post-operative, braking parameters remained reduced at 26-weeks, suggesting continued loss of elbow function following subtotal coronoidectomy.
In a study by McLarty 2021 in VRU, what imaging technique was used to improve the detection of lesions in dogs with elbow pain?
PET-CT using 18F-Sodium Fluoride. This improved detection rate of lesions over CT alone, and was more correlated to clinical grade.
