Ch 61b Patella Flashcards
(88 cards)
1
Q
Medial Patellar Luxation in Small-Breed Dogs
Etiology and Pathogenesis
A
- MPL not present at birth in most cases, the skeletal abnormalities that predispose to this condition are
- Therefore, it is a developmental disorder
- underlying cause not entirely understood
underlying skeletal abnormalities
1.coxa vara (a decreased angle of inclination of the femoral neck)
2.diminished anteversion angle (relative retroversion)
- lead to complex sequence of skeletal changes
- presence of the patella exerts pressure on the trochlear groove during growth > adequate depth and width.
- absence of the patella leads to trochlear hypoplasia.
- Intermittent luxation and reduction may cause progressive wearing of the medial trochlear ridge
- considered inherited, affected individuals should not be bred
2
Q
what are typical deformities of MPL? (9)
A
- malalignment of the quadriceps mechanism (medial)
- coxa vara (decreased angle of inclination)
- femoral varus and genu varum
- shallow trochlear groove with poorly developed ridges
- hypoplasia of the medial femoral condyle
- medial displacement of the tibial tuberosity,
- internal rotation of the tibia relative to the femur,
- proximal tibial varus,
- internal rotation of the foot
theory has been questioned because coxa valga was identified as a significant risk factor
tibial valgus, though considered to be a compensatory change
3
Q
version of the femoral neck, also known as femoral neck anteversion (FNA) or femoral torsion, is the angle between the femoral neck and the femoral condyles:
A
4
Q
Epidemiology and Pathophysiology of MPL
medial %? bilateral %?
concurrent CCLR%?
A
- medial, lateral, or bidirectional
- some luxation is traumatic > tearing/stretching of the lateral parapatellar joint capsule and/or fascia can lead to instabiliy
- 82% developmental
- medial in 95-98%
- 2%- 5% lateral
- female-to-male ratio was 1.5 : 1
- Bilateral in 50% to 65%
- complication secondary to CCLR Sx
-> rate of 0.018%, mostly in larger (≥20 kg) dogs - thesis by Putnam: primary changes in the hip joint (coxa vara and diminished anteversion angle) are proposed to influence development and eventual malformation in the remainder of the pelvic limb.
- mild, moderate, or severe lameness, associated with grade
- Skeletal deformities more severe as grades increase
- Lameness likely related to the degree of cartilage erosion from patella and the medial trochlear ridge
- bilateral cases > crouched gait with stifle joint hyperflexion and internal tibial rotation
- Concurrent CCLR 15% to 20% (older + chronic MPL), unclear whether this truly occurs secondary or simply a manifestation of CCL disease
CCLR may occur secondary > cruciate ligament is placed under increased stress because the quadriceps mechanism is ineffective in stabilizing the joint
5
Q
Q-angle
A
- Deviation of the direction of force of the quadriceps femoris muscle
- MRI: origin of the rectus femoris muscle, the deepest point of the trochlear groove, and the attachment of the patellar ligament on tibial tuberosity
- normal = 10.5 degrees
- grade 3 = 36.6 degrees
6
Q
Grading System for Medial Patellar Luxation
A
- Grade 1 luxation is commonly an incidental finding
- Grade 2 luxation typically causes intermittent lameness, internal tibial rotation with flexion causes the patella to luxate, mild femoral varus, tibial valgus, and internal tibial rotation
- Grade 3 luxation may be mild, moderate, or severe lameness, patella is continuously luxated during ambulation
- grade 4 luxation, marked varus and internal tibial rotation, debilitating; crablike posture and must be carried
- acute worsening of chronic lameness may be assocaited with CCLR
7
Q
MPL diagnosis
A
- grading of individual cases is based primarily on physical examination
- rule out concomitant cranial cruciate ligament disease (effusion, thrust, draw)
- walk and a trot is performed to evaluate overall conformation and to screen for overt skeletal deformity
- patellar ligament can be followed proximally from its attachment on the tibial tuberosity until the patella is located
- deterimine reducibility and direction
- patella alta or baja
- depth of the trochlear groove can be estimated by palpation
- alignment of the quadriceps mechanism assessed
RADS
- document luxation and assess the degree of degenerative changes
- identify and quantify skeletal abnormalities in severe cases
- skeletal deformity is present, orthogonal views of the femur and of the tibia, in addition to orthogonal views of the stifle
- Skyline views of the femur trochlear
- consider CT for derformities
8
Q
decision making for MPL
- grade 1
- grade 2
- grade 3&4
- immature
A
- all the abnormalities are identified so that individualized treatment is provided for each patient
- medialization of the tibial tuberosity and/or a shallow trochlear groove should be corrected
- potential for OA to progress/develop
grade 1
- with no associated clinical signs, treatment is conservative.
- If lameness develops, it should be reevaluated
grade 2
- significant clinical signs, surgery is indicated, criteria includes:
- (1) significant episodes of lameness lasting 2 to 3 weeks or longer
- (2) three or more significant episodes of lameness that occur in a short time frame (1 month)
- occasional, mild lameness is not as straightforward (monitor for lameness, pain, OA progression)
grade 3 or grade 4
- surgical correction is warranted early
- to mitigate progressive skeletal deformity and osteoarthritis
very young patient with significant growth potential
- challenging
- Bony reconstructive techniques could result in damage to physes (avoid if significant growth potential)
- two-stage repair should be considered
- soft tissue reconstruction techniques +/- trochlear chondroplasty
- trochlear recession, TTT, and osteotomy of the femur once skeletal maturity
9
Q
OA develops in MPL
A
10
Q
MPL surgery (3)
A
- based on realignment of the quadriceps mechanism and stabilization of the patella within the trochlear groove
1. Extensor realignment by transposition of the tibial tuberosity, derotation of the tibia and/or correction of femoral varus.
2. patella stabilized in the trochlear groove by deepening and widening the groove
3. soft tissue balance by release of contracted tissues and by imbrication
11
Q
Trochleoplasty
A
- goal: approximately 50% (or slightly less) of the patella protrudes above the trochlear ridges
- Histologic examination: cell loss and minor fibrillation confined to upper layers + no change in glycosaminoglycan content
- findings support the use of surgical techniques that preserve the hyaline cartilage
12
Q
Trochlear Sulcoplasty
A
- abrasion trochleoplasty
- articular cartilage and several millimeters of subchondral bone are removed
- initially filled with well-vascularized, highly cellular, loose connective tissue > reorganized into fibrocartilage
- results in complete loss of the hyaline cartilage
- study: muscle atrophy, palpable crepitus, and severe erosion of the articular cartilage of the patella as early as 4 weeks following trochlear sulcoplasty
13
Q
Trochlear Chondroplasty
dogs younger than 6 months
A
- articular cartilage can be gently separated from the underlying subchondral bone
- elevated with a periosteal elevator, and several millimeters of subchondral bone is removed with a curette, rongeur, or rasp
- can be difficult to achieve
14
Q
Trochlear Wedge Recession
A
- geometric theory of similar triangles
- osteochondral autograft is developed from the trochlear sulcus
- cut is made slightly axial to the peak of each trochlear ridge to just proximal to the intercondylar notch.
- defect is deepened
- wedge fits exactly, achieving immediate stability, recession of articular surface, and a relative increase in height of ridges.
- Retropatellar pressure and congruence between the cut surfaces create suitable friction to stabilize the wedge without the need for internal fixation
- defect can be deepened in various ways: two additional osteotomies to remove a V-shaped piece of bone or only one on one side
- saw blade kerf may be sufficient to achieve adequate recession
fine-tooth, thin-kerf hobby saw blade, sagittal saw
15
Q
principles of recession technique
A
- must be wide enough to accommodate the patella, or the patella will ride along the trochlear ridges
- wedge must have the same apex angle to achieve stability of the wedge via press-fit (subsequent osteotomies are performed parallel to the firs)
- depth of the trochlear groove should accommodate approximately 50% of the depth of the patella
- articulates with the patella throughout its normal range of motion
- minor discrepancies in angulation, the apex of the osteochondral wedge can be removed
- dislodging the wedge because it may fall from the surgical field
16
Q
what to do with droppped osteochrondral graftd
A
- Five minutes of cleansing with a 10% povidone-iodine solution followed by a normal saline solution rinse appears to provide the optimal balance between effective decontamination and cellular toxicity for dropped autologous bone in the operative setting.
- provided decontamination in 10.4% of the incidents.
- up to 70% contamination rate in human surgery
17
Q
Trochlear Block Recession
A
- to maximize preservation of hyaline articular cartilage
- abaxial margins of the rectangular osteochondral autograft are defined
- angled approximately 10 degrees axially, results in a press-fit
- from the proximal transtrochlear margin in the suprapatellar region to the distal transtrochlear margin near, but not entering, the intercondylar fossa
- osteotomy is initially directed perpendicular to the bone surface
- straight basilar osteotomy is performed to connect the proximal and distal transtrochlear margins
- alternately advancing from the proximal and distal margins > may help prevent fracture
- to deepen it: section from graft or from bed
- firmly pressed in place with a smooth-handled instrument to achieve a press fit
- proximal step defect is present and interferes with patellar tracking, it can be removed with a rongeur.
- The joint is copiously lavaged.
18
Q
pro’s of block over wedge (4)
A
- increased proximal patellar depth,
- increased patellar articular contact with the recessed proximal trochlea,
- recession of a larger percentage of the trochlear surface area,
- greater resistance to patellar luxation in an extended position
experimental study
19
Q
craniolateralization of TT (CrLT) may be advantageous in terms of the contact mechanics of the PFJ in canine MPL
A
20
Q
Tibial Tuberosity Transposition
what k-wire mm?
A
- Medial displacement of the tibial tuberosity can be corrected
- assess patellar tracking: If the line of action of the patellar ligament is not centered on, and parallel to, the trochlear groove, then a tibial tuberosity transposition is warranted (typically obliquely directed)
- osteotomy should start at least 3 to 4 mm proximal to the attachment of the patellar ligament and should extend to the distal extent of the tibial crest
- approximately one-half of the depth of the tibial crest measured from the patellar ligament attachment to the cranial articular margin of the tibial plateau
- of sufficient size to be reattached with implants
- preferably leaving the distal periosteal attachment intact
- Flexion of the stifle joint will increase tension on the patellar ligament and will stabilize the tuberosity in the new position
- 2 x 0.035 (0.9 mm) to 0.062 (1.6 mm) Kirschner wire placed parallel in the widest portion of the tuberosity
- very small patients, one proximal to the other
- slightly distally and in a caudomedial direction (aiming distal to the fibular head)
- bone tunnel is drilled in the tibial crest 3 to 10 mm caudal and slightly distal to the distal extent of the osteotomy
- figure of eight pattern to create a tension-band wire; it is tightened with one or two twist knots
- alternative to FO8 wire: Kirschner wires within the tibial crest, or notch in the recipient bed of the tibia and fixation with a single Kirschner wire
21
Q
pin and tension band
A
- FO8 effectively counteracts the distractive force of the quadriceps mechanism and is associated with a very low rate of implant loosening and/or Kirschner wire migration.
-
Zide 2020 – pin and tension band wire significantly stronger than pins alone for TTT
- pin orientation (level horizontal vs vertical) did not affect construct strength
- Hawbecker 2023 - 0° K-wire insertion of TTT → stronger than 30° when applied without TBW
- Cashmore 2014 - more caudodistal direction of K-wire → higher risk of TT avulsion
22
Q
k-wires
A
23
Q
soft tissue recon for MPL
A
- Retinacular release is the release of contracted retinacular tissues (fascia and other tissues) medially
- Capsulotomy is release of the contracted joint capsule
- release to proximal extent of the joint or beyond if necessary
- left open to prevent tension redeveloping; the synovial defect will quickly seal to prevent undue synovial fluid leakage
- For grade II/IV: the quadriceps femoris muscle can be released by making an incision: between the vastus medialis and the sartorius muscle, laterally between the vastus lateralis and the biceps femoris
- entire quadriceps mechanism can be freed of restrictive tissue connections
- ## Imbrication of soft tissues, joint capsue and or fascia, vest-over-pants (modified Mayo mattress) pattern; monofilament absorbable sutures
24
Q
Antirotational Techniques
A
- mature animals, antirotational techniques are likely insufficient unless the underlying bony abnormalities are addressed concurrently
- consider doing for stage 1 immature repair: fabellotibial suture placed from the lateral fabella to the tibial crest results in external rotation of the tibia, thus moving the tibial tuberosity into a more lateral position
25
oucome small breed
complication rate: 13-48%
- increased with: grade – Gr4 → 12.8-21% revision (Hans 2016, Dunlap 2016)
+/- bodyweight, bilateral single-session, age
- reluxation: 8-48%
- increased with: larger breed
- decreased with: trochleoplasty (Arthurs 2006, Cashmore 2014, Perry 2017)
TTT (Arturs 2006,
release of cranial belly of sartorius (Cashmore 2014)
lower grade (Wangdee 2013)
- TT avulsion: 3.8-4.6%
- K-wire placement (Cashmore 2014)
26
MPL in Large-Breed Dogs
- Etiology and Pathogenesis
- not entirely understood
- believed that coxa vara and a diminished anteversion angle are the underlying skeletal abnormalities
- coxa valga has been identified > bringing this theory into question
malalignment proposed to lead to:
- genu varum (bowlegged)
- distal femoral varus (bows toward midline)
- hypoplasia of the medial condyle
- external torsion of the distal femur
- a shallow trochlear sulcus with poorly developed ridges;
- proximal tibial varus or valgus
- internal tibial torsion
- medial displacement of the tibial tubercle
27
concurrent CCL in large-breed?
41%
28
The main difference between pathogenesis and pathophysiology is that pathogenesis is the process of how a disease develops, while pathophysiology is the study of the physiological changes that occur in the body as a result of a disease
29
Epidemiology and Pathophysiology
| prevelence, incidence, L:P
- **prevelence** of medial vs lateral: small 98%, medium-size 81%, large breeds 83%, giant-breed 67%
- medial patellar luxation is still more common
- **incidence** in large-breed dogs appears to be increasing (40% in recent study)
- Evidence is insufficient to establish the exact sequence of events
- Abnormal medial tension of the extensor mechanism exerts uneven pressure on the distal femoral physis > femoral varus deformity
- **distal femoral varus **plays a significant role in medial patellar luxation in the large-breed dog
- compensatory proximal tibial valgus occurs > radiographic examination reveals a sigmoid skeletal structure
- patellar ligament length (L) to patellar length (P): significantly more proximal (patella alta) compared with normal dogs
- large-breed dogs with an L:P ratio greater than **1.97** were considered to have patella alta
- **larger aLDFA** was identified in the patellar luxation group
30
Rate of MPL complication secondary to the treatment of CCLD?
0.018%
31
diagnosis - common concurrent conditions to MPL (4)
1. hip dysplasia
2. CCLD
3. angular or torsional malformation of the femur
4. torsional or angular malformation of the tibia
32
Diagnostic Imaging
craniocaudal
- (femoral varus +/- tibial varus/valgus)
- horizontal beam for true CC
mediolateral
- (double condyle sign i.e., not superimposed > one cranial to the other = torsional deformity, distal to the other = angular deformity)
- extensor fossa (present on the lateral femoral condyle)
- magnitude of femoral varus determine by aLDFA and CORA for osteotomy position (either rads or CT)
axial view of the femur
- (torsion)
CT
- 3D volume more accurate for deterimine corrections for deformaties
-
33
well-positioned craniocaudal view of the femur: (4)
1. fabellae bisected by the femoral cortices,
2. parallel walls of the intercondylar notch,
3. partially visible lesser trochanter,
4. nutrient foramen roughly centered between the femoral cortices
34
normal aLDFA
- center of the femur at 33% and 50% > line connecting these two = anatomic axis of the femur
- aLDFA is measured at the intersection of the anatomic axis and the distal joint reference line
- **94 to 98 degrees**
- if varus deformity is present CORA is determined
35
Femoral anteversion angle (torsion)
- **range 12 to 40 degrees**
- dorsal recumbency and the hip joint flexed such that the x-ray beam is directed down the center of the femoral diaphysis, with the cassette under the hip joint.
- femoral torsion angle (anteversion angle) = intersection of the transcondylar axis and an axis through the center of the femoral head and neck
- breed specific not really available
- medium -large breed average: 31 degrees
- small average: 25 degrees
- STUDY: correct if less that 27
36
Corrective Osteotomy of the Distal Part of the Femur
- techniques (4)
- associated with a very low rate of recurrent patellar luxation
1. lateral closing wedge ostectomy,
2. medial opening wedge osteotomy,
3. detorsional osteotomy
4. radial osteotomy
closing wedge is biomechanically more stable than an opening wedge
37
Corrective Osteotomy of the Distal Part of the Femur
determine:
- **CCLD** present > 14 of 30 stifle joints, common for two conditions in many large-breed dogs.
- distal femoral varus appears to be innocuous until cruciate ligament disease begins to occur.
- **CORA** location and magnitude and the femoral torsion angle
- severity of medial displacement of the tibial tuberosity or **tibial** torsional abnormalities
-
38
Corrective Osteotomy of the Distal Part of the Femur
- surgery
| post-op
- jig pins are placed parallel to the sagittal plane of the femur.
- If a femoral torsion, pins parallel to the sagittal plane of the proximal femur
- osteotomy is planned to ensure that the distal femoral segment is large enough to accommodate at least three plate screws
- locking plate, LC-DCP or distal femoral osteotomy plate
- ostectomy completed adn reduced/compressed (redction forceps, wire arouond jig pins)
- Torsional correction is performed by bending the distal jig pin (angle of pin measured with a goniometer)
- CT san > 3D printed cutting guide?
- leaving the last screw hole open/monocortical until after the trochlear wedge or block recession is performed
- Cancellous bone from the closing wedge osteotomy can be morselized
post-op
- leash walks only for 4 to 6 weeks
39
CCLD and large dog MPL
- CCL rupture, stifle joint instability (internal rotation) appears to initiate patellar luxation or exacerbate quiescent grade 1
- Tx: TPLO procedure with internal tibial torsional correction can be used
- modified TPLO
- TPLO with CCWO
- TPLO with TTT (TTT osteotomy starts within the radial osteotomy at the location of the cranial extent of the tibial plateau segment)
- vs TTTA, modifed TTO, CCWO + TTT
40
Complications large breed MPL
- rate?
overall rate 18% (high if weigh >20kg)
- delayed union 3%
- fixation failure at the osteotomy sites,
- reluxation of the patella (8%, older reports up to 50%)
- infection 7%
- osteoarthritis (progression in many joints)
Cases treated with TTT and trochleoplasty associated with lower risk of patellar reluxation and major complications (5.1-fold reduction)
41
Prognosis large breed MPL
Grade II-III
- good
- overall coplications 18%
Grade IV
- fair to good
- poor (deformity, osteoarthritis, cartilage loss, muscle atrophy)
- overall complications 25%
- Full to acceptable function was reported in 82% to 93%
- deformity correction is an important component
42
cats MPL
Beer 2023 – high-grade MPL → lower aLDFA, AA, tibial torsion, TT displacement and trochlear
depth:patella thickness ratio (T:P)
- small sample sizes
Brioschi 2020 – CT assessment of block recession sulcoplasty vs partial parasagittal patellectomy
- femoropatellar contact significantly reduced after block recession and significantly
increased after patellectomy
- PPP → mean 20% reduction in bone volume, ~50% reduction in bone width
Rutherford 2015 – complications after MPL correction in cats, n=85
- complications: overall 26%
- 20% major: 5% reluxation
- higher risk of major complication with TTT, Gr4, previous femoral # and
previous stifle surgery
- outcome: 74% successful
43
Lateral Patellar Luxation in Dogs
Etiology and Pathogenesis
- coxa valga, increased angle of anteversion (femoral torsion angle
- genu valgum
- large breed
- exact cause remains unproven
44
Epidemiology and Pathophysiology
- 2% small-breed dogs,
- 19% in medium breeds,
- 17% in large breeds
- 33% in giant breeds
- lateral patellar luxation lead to altered loading of the femoral condyles during development.
- Increased forces through the lateral distal femoral physis > retard growth of the lateral aspect of condyle (normal on the medial aspect) resulting in distal femoral valgus and lateral condylar hypoplasia
- results in genu valgum (knock-knee deformity)
- associated with a relatively long proximal tibia and patella baja.
- If patellar luxation occurs early in life during the development of the femoral trochlea, a shallow or absent trochlear groove may result as well as wearing and shortened lateral ridge.
45
Dx of lateral patella luxation
- Bilateral involvement is very common in these cases
- begin to show clinical signs by 5 to 6 months of age
- palpable thickening of the medial retinacular tissue > secondary to chronic irritation as it glides over the trochlear ridges
- excessive laxity of the medial collateral ligament may be noted secondary (also check for CCLD)
- radiographs or CT of the femur and tibia are necessary to quantify the deformities present (distal femoral valgus and/or torsion)
- measure aLDFA and the femoral torsion angle
- 94 to 98 degrees (4 to 8 degrees of femoral varus) in the absence of a breed-specific value.
46
Tx of lateral patella luxation
- corrective osteotomy to correct femoral alignment in the frontal plane and/or femoral torsional alignment based on CORA location and magnitude and on the magnitude of the femoral torsion angle
- femoral torsion angle is greater than 27 degrees, the authors consider correction
- femoral trochleoplasty, tibial tuberosity transposition, lateral release, medial imbrication +/- tibial corrective osteotomy
osteotomy
- medially based closing wedge ostectomy,
- lateral opening wedge osteotomy,
- detorsional osteotomy
- radial osteotomy
closing wedge is biomechanically more stable than an opening wedge
47
Complications and Prognosis lateral patella luxation
- similar to MPL
complications following lateral closing wedge distal femoral ostectomy:
- infection (2/51; 3.9%),
- fixation failure (1/51; 1.9%),
- delayed healing (2/51; 3.9%),
- persistent lameness (1/51; 1.9%)
- reluxation 0% in one retrospective study
48
While some
studies have reported that neither the presence of pre- or postoperative patella alta had any relation to the incidence of patellar
reluxation (Cashmore et al. 2014), other studies have reported
a 0% patellar reluxation rate when patella alta was specifically
corrected (Segal et al. 2012).
49
Factors which have variably been associated with a reduced
reluxation rate: (4)
1. trochleoplasty (Arthurs & Langley-Hobbs 2006, Cashmore et al. 2014,
Perry et al. 2017),
2. performing a TTT (Arthurs & LangleyHobbs 2006),
3. performing release of the cranial belly of the Sartorius muscle (Cashmore et al. 2014)
4. lower grade of luxation (Wangdee et al. 2013).
50
Review: Canine medial patella luxation
Perry 2021
**complication rate: 13-48%**
- increased with: grade – Gr4 → 12.8-21% revision
+/- bodyweight, bilateral single-session, age
**reluxation: 8-48%**
- increased with: larger breed
- decreased with: trochleoplasty
TTT, release of cranial belly of sartorius, lower grade
**TT avulsion: 3.8-4.6%**
- K-wire placement (Cashmore 2014)
51
Etiology:
Yasukawa 2016 – GrIV MPL in toy poodles
significantly increased: aLDFA, mLDFA, FVA and TTA
- significantly decreased: AA, medial distance of TT to proximal tibial width (MDTT/PTW)
[internal tibial torsion], patellar size (hypoplasia)
52
Computed tomographic measurements of the femoral
trochlea in dogs with and without medial patellar luxation
Longo 2023
femoral trochlear groove angle (FTGA) on CT for assessment of trochlear groove
depth
- proposed cut-off: small breed: <134°; medium-large breed: <128°
- for not requiring trochleoplasty (larger angle = shallower groove)
53
Cashmore 2014
major complication rate 18.5%
- recession trochleoplasty + TTT → 5.1x reduction in rate of reluxation
- TT avulsion 11.1 higher risk with single K-wire vs 2 K-wires
- more caudodistal direction of K-wire → higher risk of TT avulsion
54
- patella alta
patella ligament length:patellar length (L:P) >2.06
distance from prox ptella to femoral condyle:patella length (A:P) >2.03
55
- patella baja
A:P <1.92
56
Medial patellar luxation induces cartilage erosion
in dogs: a retrospective study of prevalence and
risk factors
Kim 2024
retrospective review was conducted on 90 dogs
**prevalence of cartilage erosion: 47.6% - 54.4%**
increasing with a higher grade of patellar luxation.
extent significantly associated with age, patellar luxation grade, duration, body weight
Early surgical treatment is recommended, especially for dogs with higher body weight and higher grade of MPL, to prevent cartilage erosion and secondary osteoarthritis.
57
Short-term outcomes for surgical
correction of feline medial patellar
luxations via semi-cylindrical
recession trochleoplasty
Deom 2023
3 cats
The rate of patellar reluxation at the time of final
recheck in this case series was 0/5 stifles (0%).
58
Early Surgical Management of Medial Patellar
Luxation in Juvenile Dogs
Carrera 2024
age: 7.2 months average
Four of the five patients were treated surgically with closing wedge
osteotomy of the distal femur, and three of them underwent tibial tuberosity
transposition simultaneously. Only two animals required trochleoplasty.
followed up to 1 year
postoperatively, with maintenance of extensor alignment and no late complications.
little evidence to support surgical treatment modalities for growing patients affected by medial patellar luxation
59
Trochlear Ridge Prostheses for Reshaping Femoral
Trochlear Ridges in Dogs with Patellar Luxation
Tommaso Nicetto 2024
Retrospective. Trochlear Ridge Prostheses. Dogs. follow-up short-term
A specific canine bone anatomical replica, a cutting guide, and a titaniumTRP were designed implanted in 60 femoral trochleae
- 3 complications: two minor and one major (patellar luxation recurrence). Neither implant loosening nor infection was observed.
- 45/48 of dogs returning to normal function.
perforated plate > optimal press-fit impaction and promotes osteointegration.
benefit of nominal damage to the femoral trochlear cartilage
cons > cost and time
60
PGR
Retrospective case series
Thirty-five cases, grades II to IV
Complications occurred
in six patients, of which three required revision (2x medial tilting of the patella, 1x implant failure, 1 x reluxation). Complete resolution of subjectively- assessed lameness was evident in 31/35
in combination with patellar
groove replacement including tibial tuberosity transposition, distal femoral osteotomy, proximal tibial osteotomy, tibial plateau levelling osteotomy or tibial tuberosity
advancement
decrease the lameness associated
with severe femoro-patellar arthritis, to improve patellar stability, and to correct the
alignment of the extensor mechanism.
61
Complications and Long-Term Outcomes after
Combined Tibial Plateau Leveling Osteotomy and
Tibial Tuberosity Transposition for Treatment of
Concurrent Cranial Cruciate Ligament Rupture and
Grade III or IV Medial Patellar Luxation
Redolfi 2024
retrospective study.
Twenty-four stifles (22 dogs
Four major complications: SSI (n=3) and recurrent grade II MPL (n=1)
Minor complications in five cases
long term >1yr
23/24 stifles had a complete resolution of MPL
21/22 dogs were clinically
sound
compared favorably
with some previous studies reporting up to 10% major
complication rate (patellar re-luxation, implant failure)
Patellar ligament thickening was the most frequently
encountered complication in 8/15 stifles
patellar thickening was due:
- surgical trauma by the
saw blade,
- placement the pins through the distal patellar ligament),
- early excessive activity,
- a change in stifle biomechanics,
- a combination of these remains unknown
62
list methods to correct MPL and CCLD (6)
1. extracapsular stabilization and tibial tuberosity transposition (TTT),
2. tibial plateau leveling osteotomy
(TPLO) and TTT (TPLO-TTT),
3. TPLO with lateral translation of the distal tibial segment,
4. TPLO and additional transverse
osteotomy,
5. TTTA
6. modified TTO
63
Ideal Anchor Points for Patellar Anti-rotational
Sutures for Management of Medial Patellar
Luxation in Dogs: A Radiographic Survey
Mazdarani + Miles 2023
Retrospective radiographic survey was performed on 110 stifles
The fabella is unlikely to be the best choice for anchoring a patellar antirotational
suture. Use of the best-fit circle centre to place a suture anchor should be
preferred to maximise suture isometry during joint flexion and extension in large and small breed dogs.
64
Measurement of Femoral Trochlear Morphology
in Dogs Using Ultrasonography
Akari Sasaki 2023
The ultrasonographic measurement method is reliable for the evaluation
of femoral trochlear morphology in normal dogs. The contour of the articular cartilage surface
of the femoral trochlea is already determined early in life, and ossification of the
articular cartilage of the femoral trochlea proceeds until 6months of age
65
Partial Parasagittal Patellectomy in Dogs: A Retrospective Case Series of 19 Dogs
Dumitru 2023
Vezzoni
| technique previously described by
retrospective. Partial Parasagittal Patellectomy in Dogs. 24 stifles
minor complications (4 block fracture, 1 TTT avulsion)
no major complications. No relaxation.
Increased thickness patellar ligament were noted in 14 stifles
report 20% of cases required patellectomy
+ block recession trochleoplasty and TTT resolution of in grade 2 or 3 luxation
patella–trochlear groove mismatch > similar to cats. prevents the
patella from being effectively recessed
long-term > effect on stifle mechanics and progression of OA
66
Evaluation of Surgical Technique and Clinical Results
of a Procedure-Specific Fixation Method for Tibial
Tuberosity Transposition in Dogs: 37 Cases
David Onis 2023
Surgery was successfully performed in dogs weighing 2.5 to 36.2 kg.
Postoperativeminor complications occurred in 13 cases (35%) and major complications
occurred in 3 cases (8%). No implant-related complications or tibial tuberosity avulsions
or fractures were seen. Outcome related to surgery was good or excellent in all cases.
Conclusion The RLPS for TTT provides a feasible technique in a large range of patients
with MPL and lowers the occurrence of implant-related complications and tibial
tuberosity avulsion or fracture.
67
Dome trochleoplasty for correction of patella alta
and patella luxation in dogs > 20 kg
Ericksen 2023
13 dogs (16 stifle joints)
Eight of 16 stifle joints (50%) had reported complications, which were diagnosed 42 to 224 days postoperatively (mean, 101.7 days). Major complications occurred in 7 stifle joints (43.8%) due to pin migration with subsequent removal (n = 4) and reluxation (3) > relux rate 19%.
1catastrophic (significant, progressive bone resorption.)
Uncomplicated osteotomy healing was present in 94% of dogs
Concurrently performed procedures were tibial tuberosity transposition in 5 stifle joints
dome trochleoplasty technique can correct the issues with trochlear depth and malalignment of the quadriceps mechanism
need for a biradial saw blade and specialized training to use this equipment
due to its higher complication and reluxation rates, it should be used cautiously
68
The value of routine radiographic follow up
in the postoperative management of canine
medial patellar luxation
Brincin 2023
Retrospective multi-institutional case series.
Animals: Client-owned dogs (N = 825)
Isolated radiographic abnormalities were identified in 3.3%
(27/825) of dogs following MPL surgery and led to a change in recommendations
in 3% (13/432) of dogs that were presented without owner or clinician concerns
Dogs that were presented for routine follow up after
unilateral MPL surgery without owner concerns, lameness, analgesic treatment
or a history of unplanned visits, and for which examination by a surgical
specialist was unremarkable, were unlikely to benefit from radiographs
69
small breed dogs affected by grade IV
MPL had shorter QML relative to FL compared to those
with MPL grades I–III. This study supports our hypothesis
that the QML/FL is lower in dogs with higher MPL
grades
Further research
is warranted to determine the validity of QML/FL as a
predictor of the need for femoral shortening at the time
of femoropatellar joint reconstruction in dogs with
severe MPL.
70
Outcomes and complications of a modified tibial tuberosity
transposition technique in the treatment of medial patellar
luxation in dogs
Cortina 2023
Retrospective case series.
Sample population: Dogs (n = 235
lateral displacement pin and a modified tension band construct with a single Kirschner wire
low-grade reluxation(11 stifles, 3.6%)
tibial tuberosity displacement and patella alta (one stifle, 0.3%)
tibial tuberosity
fracture (two stifles, 0.6%), and high grade reluxation (two stifles, 0.6%).
All long-term complications were due to pin migration. The overall major complication
rate was 4.3%
weight ranged from 1.3 kg to 72.3 kg,
study did not provide direct evidence that this technique
is superior to other techniques within our setting
one surgeon
71
Tibial Tuberosity Transposition Fixation with a
Locking Plate during Medial Patellar Luxation
Surgery: An Ex Vivo Mechanical Study
Esa V. Eskelinen 2022
Procedure-specific locking plates for fixation of the transposed
tibial tuberosity. The plates have holes for locking screws: Plate A: 1.5
and 1.5 mm, Plate B: 2.0 and 1.5 mm, and Plate C: 2.4 and 2.0mm
screws. Plates also have three small holes (two proximal and one midplate)
for a pin or tension band wire
lower construct strength of
the Pin-TBW construct compared with the Plate-Pin construct in the raccoon dog cadaver model.
dont need tension wire with late
72
Morphological Analysis of Bone Deformities of
the Distal Femur in Toy Poodles with Medial
Patellar Luxation
Shinji Yasukawa 2021
Hypoplasia of the cranial and middle rather than caudal compartment of
the distal femur was the primary morphological abnormality in Toy Poodles with grade
4 MPL.
In
contrast, no significant bone deformities, with the exception
of a poorly developed proximal medial trochlear ridge, were
observed in the grade 2MPL group. T
73
Short-term outcomes for surgical
correction of feline medial patellar
luxations via semi-cylindrical
recession trochleoplasty
Kristen Deom 2023
3 cats, good outcome
For cats with low-grade patellar luxation (Putnam grades I and II), non-surgical management has
been reported to provide an excellent outcome in 47% and good 29%
higher-grade patellar luxations (Putnamgrades III and IV), the outcomes were not as favorable,
suggesting surgical intervention may be indicated
proposed benefits of the SCRT
over TBR include its subjectively easier application, particularly
in small patients, and the resulting rounded
osteotomy reducing the chance of fracturing of the trochlear
ridges
performed in canine MPLs, yielding
similar functional outcomes as TBR, as reported in a
recent pilot study.19
74
Comparison of semi-cylindrical recession trochleoplasty
and trochlear block recession for the treatment of canine medial patellar luxation: a pilot study
Blackford-Winders 2021
prospective, pilot study
Ten dogs with bilateral grade II-III medial patellar luxations - one stifle each undergoing TBR and SCRT
Short-term follow-up shows similar functional outcomes
machined hole saw attached to a high-speed drill, with a diameter of 4 to 18mm, in combination with a customized aiming guide
There was no difference in preoperative or 8-week postoperative
PVF or VI between techniques
In the TBR group, 3 of 10 blocks
fractured intraoperatively
There were no
patellar reluxations or other complications during the study
period.
more procise press-fit than TBR
75
Trochleoplasty in
addition to realignment of the quadriceps mechanism via
tibial tuberosity transposition results in a 5.1-fold reduction
in the rate of patellar reluxation
76
ComputedTomographicMeasurement of Trochlear
Depth in Three Breeds of Brachycephalic Dog (without MPL)
Matchwick 2021
| mielke
Retrospective. CT Trochlear Depth in Three Breeds of Brachycephalic Dog (without MPL)
validated ratio (T/P) of maximal trochlear sulcus depth (T) and maximal patellar craniocaudal thickness (P) on CT
Mean T/P was significantly reduced in the brachycephalic dog breeds
a shallow sulcus may be a breed-driven characteristic, the contribution of sulcus depth to the aetiopathogenesis of patellar luxation remains unclear.
Trochlear recession to achieve patellar coverage of 50% may be excessive considering maximal breed normal depth
need to compare to brachy’s with MPL
77
Use of Frozen Tendon Allograft in Two Clinical
Cases: Common Calcaneal Tendon and Patellar
Ligament Rupture
the case of chronic ruptures
or ruptures that do not allow edge apposition, the use of fascia lata
grafts and biological and artificial implants has also been reported
78
Treatment of feline patellar luxation
with polyethylene sulcal ridge
prostheses
Mills and Hargittai 2020
four cats. In all cases, the lameness resolved within weeks of a single
surgery. No important complications were encountered
2 years > radiographic progression of degenerative joint disease and one
showed evidence of screw loosening
UHMWPE mechanical properties degrade with time (Kurtz
et al. 2003). UHMWPE wear particles have detrimental effects
on cartilage, synovium and menisci
> not expected to be a proem in use as a ridge stop compared to THR
79
Segmental Femoral Ostectomy for the Reconstruction
of Femoropatellar Joint in Dogs with Grade IV Medial
Patellar Luxation
Yukari Nagahiro 2020
six dogs
The mean resected femoral length was 11.7mm
increased range of motion in
all dogs compared with their preoperative status.
Conclusion Segmental femoral ostectomy was a useful treatment method for MPL
grade IV with shortened quadriceps muscle length relative to the femoral length.
Reconstruction of the FPJ is important for recovery of limb function.
tibial tuberosity was reflecte
dorsally, the stifle extensor mechanism was separated from
the cranial side of the femur
80
Distal femoral osteotomy is indicated when the FVA is
above 10 to 12 degrees
81
The natural history of canine occult Grade II medial patellar luxation:
an observational study
L. Hamilton 2020
determine the risk of lameness and the rate of subsequent medial patellar luxation surgery
Retrospective owner survey and review of clinical records
Thirty-eight dogs
Fifty percent of adult dogs presenting with occult Grade II medial patellar luxation subsequently developed chronic lameness or required surgery
(i.e. the NNT was two)
for every dog in which surgery would
have prevented an adverse outcome, another dog would have received an unnecessary surgical procedure.
adult dogs, studies assessing the impact of PL surgery on radiographic progression of stifle osteoarthritis have not demonstrated a significant difference compared with non-surgically managed cases
In a study assessing the risk of untreated medial patellar luxation (MPL) on subsequent CCL insufficiency, the risk was only higher in dogs with Grade IV MPL
82
Computed tomographic localization of the deepest portion
of the femoral trochlear groove in healthy dogs
Nicetto 2020
validate a computed tomographic (CT) method to measure the
femoral trochlear groove depth (FTGD).
Computed tomography allowed precise measurements of trochlear
groove depth except for the most proximal point
The deepest portion of the trochlea groove may be
located between P25 and P50
a prospective clinical study is recommended to validate
this methodology in dogs affected by patellar luxation.
83
Computed Tomographic Assessment of Block
Recession Trochleoplasty and Partial
Parasagittal Patellectomy in Cats
Brioschi 2020
cadavers (12 stifles). CT Block Recession Trochleoplasty vs Partial
Parasagittal Patellectomy in Cats
The area of contact between the patella and femoral trochlea was significantly reduced after BRT and significantly increased after PPP.
Block recession trochleoplasty did not improve patellar recession and
decreased patellofemoral contact area. Following BRT, the patella rides the trochlear ridges
patella tipping seen
normal feline stifles the patella is up to 1mm wider than the trochlea
PPP resulted in 40 to 50% patellar recession and increased PFCA > biomechanical study would be needed to prove whether this improves patellar stability
a partial patellectomy > small reduction in PV (average 20%) while achieving a larger reduction in PW (aver age 40%)
In our experience, cats rarely have medial or lateral deviation of
the tibia tuberosity; therefore, TTT is rarely indicated.
84
A Cadaveric Evaluation of Pin and Tension Band
Configuration Strength for Tibial Tuberosity
Osteotomy Fixation
Zide 2020
- pin and tension band wire significantly stronger than pins alone for TTT
- pin orientation (level horizontal vs vertical) did not affect construct strength
the addition of a TB adds significant strength to the construct.
perpendicular to the osteotomy. In theory, this is the optimal pin orientation, to allow compression of the osteotomy when a tension band is applied
85
Heritability of patellar luxation in the Chihuahua and Bichon Frise
breeds of dogs and effectiveness of a Swedish screening programme
prevalence of patellar luxation was 23% in the Chihuahua and 12% in the Bichon Frise. Using
threshold analysis, estimated heritabilities were 0.25 for the Chihuahua and 0.21 for the Bichon Frise
slight genetic improvement over the study
period in the Chihuahua. Further genetic progress would be facilitated by selection using estimated
breeding values
86
Treatment of patellar luxation
with polyethylene sulcal ridge
prostheses in 44 feline stifles:
a retrospective study
Mills 2024
Retrospective. polyethylene sulcal ridge prostheses in 44 cats stifles
long-term 2 years . grade 2 (n = 19), 3 (n = 22) or 4 (n = 3)
minor complications in 20%
major complications in 7% (implant removal for lameness (n = 3).
DJD, with mineralisation, in 26/35 (74%) > reaction to UHMWPE wear?
good or very good long-term functional outcomes 93%
Delaying until growth is completed is advised and cats weighing <3 kg not candidates.
compared very favourably to other sx techniaques.
TRA without TTT gave good ooutcomes
authors advocate bicortical placement of TRA screws to optimise stability and reduce the risk of aseptic screw loosening
87
It has been demonstrated that the majority of physes in
cats are closed by 9 months of age
88
Factors Contributing to the Need for Non-
Elective Explant following Surgical Repair of
Tibial Tuberosity Avulsion Fracture
Aparna Arun 2022
Retrospective multicentre case–control study. Over a 5-year period,
dogs (n¼63)
Non-elective explant was performed in 20/64 fractures and elective explant
was performed in 2/64 fractures
Every 0.25mm increase in average pin size was found to make it 2.5 times more likely to require explant
use of a
tension band construct in tibial tuberosity avulsion fracture
repair is a useful technique to considerminimizing the risk of
requiring an additional surgery for non-elective explant
