Ch 52 - Surgical Diseases of the Elbow Flashcards
List the extensor muscles of the elbow joint
What innervated these muscles?
Extensors are innervated by the radial nerve and include:
- Triceps brachii
- Tensor fascia antibrachii
- anconeus muscle
List the main flexors of the elbow joint and the associated nerve
- Biceps brachii - musculocutaneous n
- brachialis m - musculocutaneous n
- Extensor carpi radialis - radial n
What is the normal range of motion of the elbow?
At what point of extension does the anconeal process articulate with the olecranon fossa?
Normal range of motion 130 deg
- 36 flexion
- 165 extension
- At 135deg, anconeal process articulates with olecranon fossa
What is the Campbells test?
Testing rotation stability via the collateral ligaments with the elbow and carpus held at 90deg
What are the three regions of conctact in the elbow?
- Craniolateral aspect of anconeal process
- Radius
- Medial coronoid process
How much of the weight through the elbow goes through the radial head?
51%
Which direction is most common for traumatic elbow luxation? Why?
What position does the elbow need to be in to allow for luxation?
Lateral (92 - 100%)
- Relatively large humeral trochlea
- MCL is inherently weaker
Elbow must be flexed beyond 45 degrees to unlock the anconeal process from the olecranon fossa
What percentage of dogs with traumatic elbow luxation will have concurrent collateral ligament damage?
18 - 50%
What approach is recommended for open reduction of elbow luxation?
Caudolateral
What are the options for post-op immobilisations after elbow reduction?
- Spica splint
- ESF (connecting bars can be replaced by tight elastic bands to allow some early motion)
- Potentially also the transarticular fixation (screw or pin)
What are the three types of congenital elbow luxation?
- Type I: Humeroradial
- Type II: Humeroulnar
- Type III: Combined
How do you treat Type I humeroradial luxation?
- Oblique osteotomy or wedge ostectomy of radius with bone plate or ESF
- Reduction maintained with temporary transarticular pin or intraosseous screws between radius and ulna
- Spica spint or carpal flexion bandage
What breed of dogs have the highest odds ration of UAP?
What percentage of dogs with UAP will also have FMCP?
How often is UAP bilateral?
- Bernese Mt Dogs and Mastiffs
- 13 - 30% have concurrenct FMCP
- Bilateral in 20 - 35%
Define positive and negative radioulnar incongruence
- Positive: Ulna longer than the radius
- Negeative: Radius longer than ulna
At what age does the anconeal process growth plate fuse?
- 14-15wk in Greyhounds
- 16-20wk GSD
What are the Tx options for UAP?
- Anconeal process removal (owners satisfied but only 50% free of lameness)
- Reattachment (dogs under 24 weeks with normal trochlear notch, 60% fusion 2-6m)
- Ulnar osteotomy/ostectomy
- Reattachment and ulnar osteotomy/ostectomy (best outcome: fusion 93%)
What are some guidelines for an ulnar osteotomy for the Tx of UAP?
- Most successful in dogs under 7m with firmly attached, non-displaced anconeal process
- Osteotomy located 30-60mm distal to articular surface
- Bi-oblique: proximocaudolateral to distocraniomedial at 40-50 degrees to long axis
- +/- IM pin
What breeds are predisposed to flexor entheseopathy?
Labradors, GSD, English Setter
What percentage of flexor entheseopathy is primary?
15 - 35%
What test can be performed to test for pain associated with flexor entheseopathy?
Extending the carpus while holding the elbow at 90 degrees
What are the treatment options for primary flexor entheseopathy?
- Conservative
- Intra-articular methylpred
- Tenotomy
- Partial excision
- Resection of osseous bodies
What breeds are predisposed to FMCP?
What % also have elbow incongruity?
What % is bilateral?
- Labs, GSD, Rottweilers
- 60% concurrent incongruity
- Bilateral 25 - 80%
Regarding FMCP, at what age can subchondral defects been seen?
At what age are articular cartilgate lesion reported to become visible?
- Subchondral defects 15 weeks
- Articular cartilage defects 18 weeks
Glycosaminoglycan content depletion of the articular cartilage parallels the subchondrl bone defects.
What is thought be the cause of FMCP?
Delay of endochondral ossification and biomechanical forces acting on the coronoid
- Overloading may occur due to inconguence, humeroulnar conflict, or joint instability
How can negative radioulnar incongruence (short ulna) increase pressure within the medial joint compartment?
(Angular-vector-model)
Force from relatively long radius applied to the lateral aspect of humeral condyle resulting in rotatory moment (anconeal process is pivot point), rotating medial aspect of humeral condyle distally , thereby increasing pressure at the medial coronoid process
What is the percentage of positive and negative incongruence in elbows with FMCP?
- Positive (short radius) - 45%
- Negative (short ulna) - 14%
Describe the Modified Outerbridge Scoring System
- MOS 1: Cartilage softening anf swelling
- MOS 2: Partial thickness surface defects, fibrillation
- MOS 3: Deep fibrillation to subchondral bone
- MOS 4: Full thickeness cartilage erosion
- MOS 5: Subchondral bone eburnation
What is the synovial fossa?
A normal cartilage-free area of the lateral aspect of the trochlear notch, approx half way between tip and radial incisure
What is the synovial fossa?
A normal cartilage-free area of the lateral aspect of the trochlear notch, approx half way between tip and radial incisure
What is the internation elbow working group (IEWG) grading system for developmental elbow disease base on radiographs?
- 0 = Normal elbows
- 1 = Mild: osteophytes less than 2mm high, subtrochlear sclerosis but trabecular pattern still visible
- 2 = Moderate: Osteophytes 2-5mm high, obvious subtrochlear sclerosis (no trabecular pattern). RU step 3-5mm, indirect signs of primary lesion
- 3 =Severe: Osteophytes over 5mm high, RU step over 5mm, obvious primary lesion
What radiographic view may increased the sensitivity of FMCP?
DMPLO-35 degrees
What radiographic view if best used to assess for elbow incongruity?
90 degree flexed lateral
- Sensitivity 100% and specificity 70-90% for incongruity over 2mm
What is the incidence of false negatives on CT scan for assessment of Elbow Dysplasia?
29% - Cannot assess the articular cartilage (MRI can)
What is the most common technique for assessing incongruence?
The duplicated circle technique
What are the 4 types of medial coronoid process shape?
Which is most common in normal elbows?
- Type 1: Round
- Type 2: Pointed
- Type 3: Flattened
- Type 4: Irregular
Type 1 most common in normal elbows
Type 4 indicative of FMCP
What limb positioning is more helpful for viewing the medial coronoid process during elbow arthroscopy?
What fluid pump setting are typically used for elbow arthroscopy?
- Abduction and pronation
- Fluid pump set to 70mmHg (50-100) with rate of 1-1.4L/min
During arthroscopy, what positioning is used to assess congruity?
Elbow joint in a neutral position at a standing angle of approx 135 degrees
During elbow arthrotomy, what procedures can be performed if exposure is suboptimal?
- Osteotomy of medial epicondyle
- tenotomy of pronator teres
What are the reported complication rates of elbow arthroscopy?
- Infection 0.2%
- Major complication needing additional surgery 4.8%
- Conversion to open arthrotomy 5%
- Iatrogenic superficial cartilage injury 15%
What materials are used for the SynACart synthetic osteochondral transplant?
- Titanium mesh base
- Thermoplastic polycarbonate urethane surface
What are some recommendations/guidelines for a dynamic distal ulnar ostectomy? (DDUO)
- Only effective in young puppies (4-6m)
- Performed subperiosteally, removing 4-5mm, approx 2-3cm proximal to distal physis
- Preserve periosteal envelope to prevent synostosis
What are the recommendations for performing a bi-oblique proximal ulnar osteotomy?
- Mean angle of 45° caudal to cranial
- Mean angle of 48° lateral to medial
- Interosseous membrane and most proximal portion of interosseous ligament should be elevated to allow translation
What movement does a PAUL produce?
Mild abduction, mild caudal tipping and mild axial rotation of the proximal segment
What is a PURO?
Proximal Ulnar Rotating Osteotomy
- 30 deg external rotation of proximal segment
- Decreased mean and peak contact pressure by 10% in medial compartment
- Increased by 25% in lateral compartment
What procedure is depicted in this radiograph?
Sliding Humeral Osteotomy (SHO)
What are the three approach options for a Canine Unicompartmental Elbow (CUE) Arthroplasty?
- Medial arthrotomy with tenotomy of flexor tendons and desmotomy of MCL
- Osteotomy of medial epicondyle
- Caudomedial approach with osteotomy of olecranon ridge
What are the Canine Unicompartmental Elbow (CUE) implants made of?
- 4-6mm diameter polyethylene plug into denuded medial coronoid process
- “figure 8” shaped cobalt chromium prosthesis into apposing humeral trochlea
Humeral element is implanted slightly proud
What is the incidence of false negatives on CT scan for assessment of Elbow Dysplasia?
29% - Cannot assess the articular cartilage (MRI can)
