Ch 53 Total elbow replacement Flashcards
What are some recent technological advances for total elbow replacements in dogs in general?
- Resurfacing, rather than screwed or stemmed components
- Titanium, rahter than cobalt chrome alloy
- ELetron beam melthing rather than bead sintering for interface surface texture
first designs: cemented, fully constrained hinged (linked systems)
TER indications
severe, intractable osteoarthritis that is not responsive or is poorly responsive to medical management
- risk of potentially severe complications and with limited revision strategies, preferentially performed in dogs with unilateral elbow osteoarthritis
- limited long-term follow-up available for the currently available systems, recommended replacement be restricted to older dogs
- When extensive periarticular osteophytes are present, a computed tomography (CT) scan with three-dimensional reconstruction of the elbow is useful for surgical planning.
Iowa State Elbow in 2001
TATE Elbow in 2008
SIRIUS Elbow in 2011.
What implant in this?
Decribe some of the features of this implant
unlinked semiconstrained two-component
5th generation Iowa State TER
- Cemented system
- Cobalt chrome humeral component
- 120deg arc UHMW polyethylene r/u component
- Porpous coated condylar surface for bone ingrowth
- humeral and radioulnar components are implanted individually in sequence
- lateral collateral ligament desmotomy + elbow joint fully luxated
- complete wedge resection of the humeral condyle and radius/ulna
- humeral and radioulnar components are sequentially cemented in place
- cancellous bone graft is inserted between the two bones, and a distal ulnar ostectomy is performed proximal to the styloid process
What impant is this?
Describe some of the features of this implant
unlinked, semiconstrained, cementless resurfacing arthroplasty system
TATE 3rd generation
- Press-fit, cementless, resurfacing design
- Titanium 3D printed humeral component and r/u backing
- Titanium nitride coating of articular surface of humeral component
- Hydroxyapatite coating of metal-bone interfaces
- 175 degree arc UHMT polyethylele r/u component with titanium backing
- Less invasive approach medial osteotomy (During implantation, both components are linked by a set plate and are inserted simultaneously “cartridge implant”)
- Posts for primary fixation are hollow and porous surface for long term stability
- osteotomy of the medial epicondyle
- elbow joint is flexed to approximately 90 degrees and then is locked in place
- custom end mill, articular surfaces are simultaneously removed
What impant is this?
Describe some of the features of this implant
unlinked semi-constrained hybrid
SIRIUS 2.0
- unlinked semi-constrained
hybrid
- osteotomies are conservative, preserving sufficient bone stock + maintaining the stress field on the distal humerus
- humeral component bears a gap between
the humeral forks for passage of the
radio-ulnar implant (optimise ROM)
- a single distal component, fixed to
the ulna only, and combined with a radial
head excision
- The radioulnar bearing is snap-fitted to a stemless, screw-fixed titanium plate with porous titanium and hydroxyapatite dual coating
- radial difference exists between the articular surfaces of the two components to decrease constraint thereby allowing for a degree of rotational movement
- press-fit of the condylar part and cement fixation of the stem (hybrid)
SIRIUS
No clinical studies
- no clinical studies
- design enable some joint laxity.
- The pre-implantation ROM in the sagittal plane was 115°, which decreased to 90° post-arthroplasty
- proposed SIRIUS 3.0 system has changed to a linked, semiconstrained prosthesis to adress post-op instability linked systems now dominate the human TER market.
What implant is this?
Describe some of the features of this implant
kyon - no further development?
BANC (Biomechanically Anatomic, Nonconstrained and Compartmental)
- Non-cemented, resurfacig design
- UHMW polyethylene conican disc press fitted over titanium cylinder and screwed into capitulum
- Shape-matched polished titaniumhemicircular component
- Primary fixation with large transcondylar screw and 2 smaller ulnar screws
IOWA and TATE
current 2 component design
- stability of unlinked prostheses is provided by the matching geometry of the prosthetic articulating surfaces and the surrounding soft tissue envelope
- transarticular forces (e.g., the forces in varus-valgus) are almost exclusively counteracted by passive soft tissue constraints (i.e., collateral ligaments),
- internal/external rotation and mediolateral translation are also controlled by the geometry of the prosthetic .
- prosthetic constraint has been shown to influence stresses at the bone-implant interface.
- single radioulnar component that eliminates motion between the radius and the ulna.
- the surgical procedure includes a radioulnar synostosis
What modifications have been made to the TATE elbow?
Hollow primary fixation posts
Hydroxyapatite coating
Reduced prosthetic constraint in rotation and mediolateral translation
Titanium
What are potential contraindications of a TER?
Bilateral elbow OA (limited revision options)
Systemic or local infections
Chronic elbow luxation
Severe malunion (Iowa state may still be ok)
Neuro dysfunction
Skeletally immature
What are the main differences in the surgical procendures for the Iowa state, TATE and BANC elbow replacements?
post-op TER
rads: implant alignment and positioning and, when appropriate, cementing technique and bone-cement-implant interfaces, as well as osteotomy reduction and fixation. Subsequent radiographic evaluations are recommended at 6, 12, 24, and 52 weeks, then yearly thereafter, to assess bone ingrowth as well as implant stability
What are the main complications seen with the Iowa State system?
Intraoperative: instability of the lateral aspect of the elbow joint and iatrogenic fracture of the humerus
- Elbow joint luxation
- fractures of the ulna
- osteomyelitis
20% Severe complications leading to unsatisfactory results
Force plate evaluation of the remaining 16 dogs showed significant and continuous improvement in peak vertical force
What are the main complications seen with the TATE elbow?
Humeral fractures
Implant malpositioning or loosening
infection (30%)
luxations have not been reported possibly because not ligament desmotmy
STUDY: Retrospective study, the long-term subjectively evaluated - “full” (24%) or acceptable (52%) function, 24% of the cases had unacceptable clinical outcomes. high rate of major (15 cases [45%]) or catastrophic (5 cases [15%]) complications
Suboptimal implant positioning in 97%
Major/catastrophic complications range from 4-65%
MINOR 8% (migration, neuropraxia
Steep learning curve
By 6-12 months, peak vertical ground force reaction better than contralateral limb and by 2yr had reached a normal value
Evaluation of the milling technique on the component-bone
interface in the TATE elbow
Gosling 2019
In vitro study on Sawbone specimens.
Sample population: Thirty identical solid foam models
In this bone model study, application of convergent or divergent forces during milling frequently resulted in greater component-bone interface gaps
and poorer post fit than when a neutral position was maintained.
Surgeons may affect implant fit within the constraints of the current arthroplasty system if they do not maintain a neutral position during milling.
Greater component-bone interface gaps and poorer post fit may affect component
osseointegration and lead to aseptic implant loosening
In man, the accuracy of the “press fit” of cementless systems has been found to influence the success rates of replacements
Instability stimulates the formation of fibrous tissue at the implant-bone interface, thus impeding osseointegration, predisposing the construct to aseptic loosening and
implant failure.
A lateral approach allows accurate and stable total elbow replacement in dogs
Woody 2024
12 skeletally mature large-breed dog cadavers, approach (lateral or medial) were randomly selected for TER in each dog
patient-specific guides were used to align the
core post
In normal cadaveric elbows, a lateral approach for TER appears feasible,
producing equivalent limb alignment, joint laxity, and joint motion to normal elbows and to TER placed using
a medial approach.
- the medial approach requires transection of the caudal branch of the ulnar nerve and sacrifice of the origin of the humeral head of the flexor carpi ulnaris.
- There may be advantages to implanting a TATE TER prosthesis using a lateral approach, including avoiding the potential interference
of the chest or the opposite forelimb with the
drill and mill during surgery. - Because of their increased precision,
in dogs, patient-specific guides are rapidly
becoming the dominant procedures for total joint replacement other than total hip replacement
STUDY (de sousa): review of 33 TATE TER in dogs did not identify an association between implant alignment and clinical outcome. However, long-term data were limited in that study.
