Chapter 87 - Angular limb deformitites Flashcards
What is a conformation deviation of the limb in the FRONTAL plane?
is defined as angular limb deformity (ALD)
angular deformities can be classified in 2 types accodringly to the etiology
acquired
perinatal
A lateral deviation of the limb distal to the point of origin is referred to as
valgus deformity
Is each lateral or medial deviation associated with a certain degree of axial rotation?
yeas each deviaty is associated with axial rotation
In foals with valgus deformities, this is displayed as an
outward rotation called
splay foot
when a medial deviation occurs is named
varus deformity
In foals with cases of varus deformities,
as an inward rotation of the feet caleed
pigeon toed
Diagnosis of angluar deformity is made with (4 things)
static exam
dynamic exam
palpation
radiography
Foals with a toed-out posture, with
or without ALD, therefore are evaluated from a ____________________(1w) position
craniolateral position
It is very important that
the toe be aligned in the same direction as the _________________(1)
It is very important that
the toe be aligned in the same direction as the carpus/tarsus. Postpone surgery
if the carpus points outward but the toes point straight
forward, a __________(1w) deformity of the distal limb is present (see
Figure 87-1, B)
if the carpus points outward but the toes point straight
forward, a varus deformity of the distal limb is present (see
Figure 87-1, B). Surgery is indicated
Figure 87-1. (A) A valgus deformity of the carpal region is evaluated perpendicular to the frontal plane
of the outward-rotated carpus. If the toe points in the same direction, the entire limb is rotated out and
surgery can possibly be postponed. (B) If the carpus points outward and the toe points forward, surgical
intervention is indicated to prevent the development of a fetlock varus deformity.
Figure 87-2. Manual pressure to the medial aspect of the carpal region of a foal suffering from valgus deformity corrects the deformity temporarily, indicating that the ALD is caused either by incomplete ossification of the cuboidal carpal bones or periarticular laxity and conservative treatment is possible. Counterpressure is applied to the metacarpophalangeal region of the same limb.
pigeon-toed foals frequently rotate their ________________joints outward while advancing the limb
pigeon-toed foals frequently rotate their metacarpophalangeal/metatarsophalangeal (MCP/MTP) joints outward while advancing the limb
The only diagnostic aid that allows determination of the exact location and provides objective evaluation of the degree of the deformity is
radiography
In the hind limbs, dorsoplantar views are less helpful because the ______and the ___________ bone are not in alignment (an angle of 5–7 degrees is recognized as normal).
In the hind limbs, dorsoplantar views are less helpful because the tibia and the third metatarsal bone (MTIII) are not in alignment (an angle of 5–7 degrees is recognized as normal).
during radiography the foal should stand
foal should stand “square.”
____________ (1w) views are the most important in the forelimbs. Here lateromedial views should additionally be obtained.
Dorsopalmar views are the most important in the forelimbs. In the hind limbs, dorsoplantar views are less helpful because the tibia and the third metatarsal bone (MTIII) are not in alignment (an angle of 5–7 degrees is recognized as normal). Here lateromedial views should additionally be obtained.
The radiographs should be taken at a right angle relative to the ________plane of the carpus and the __________plane of the tarsus.
The radiographs should be taken at a right angle relative to the _frontal plane of the carpus and the _sagittal plane of the tarsus.
The third metacarpal/metatarsal (MCIII/MTIII) and phalangeal region should be aligned in ____plane for the radiographs, allowing interpretation of the articular orientation and differentiation of deformities.
The third metacarpal/metatarsal (MCIII/MTIII) and phalangeal region should be aligned in one plane for the radiographs, allowing interpretation of the articular orientation and differentiation of deformities.
Two lines are drawn through the axis of the long bones and the bisection of the lines (also known as the _________ represents the origin of the deformity
Two lines are drawn through the axis of the long bones and the bisection of the lines (also known as the pivot point) represents the origin of the deformity.
the pivot point helps determinate whether the deviation originates in the _____or at the ________
it can be determined whether the deviation originates in the joint or at the physis.
What are the main places that ALD occur?
- cuboidal bones of the carpus or tarsus,
- in the epiphyseal region of the long bones (epiphyses, physes, and metaphyses),
- diaphyses of the long bones
- +++ frequently disproportionate growth at the level of the metaphyseal growth plates.
At what time the bones of carpus and tarsus are visible in radiography?
at 300 days
what can be the cause of incomplete ossification at the time of birth (Figure 87-4)?
These include: prematurity related to shortened gestation (<320 days);
abnormal uterine positioning;
dysmaturity related to placentitis;
placental insufficiency;
severe prolonged metabolic diseases (maternal malnutrition);
heavy parasite infestation;
colic and shock, which can alter the blood supply to the uterus;
chemical insults (vaccinations and anthelmintics), which can influence fetal development;
and thyroid abnormalities, which can influence ossification
Figure 87-3. Normal ossification of the carpus and tarsus at the time of birth. (A) DP radiograph of the carpus. All the bones are ossified adequately, and the ulnar styloid process (a) is visible. The rough surface at the medial distal metaphysis of the radius (b) represents active endochondral ossification and is normal at that age. (B) LM radiograph of the tarsus showing adequate ossification of the central and third tarsal bones (arrows). It is important that the ossification process proceed to the level of the proximal aspect of MTIII. These two radiographic views are the most relevant to evaluate ossification at the time of birth.
Figure 87-4. (A) DP radiograph of a carpal region and LM radiograph of a tarsal region of a 2-day-old premature foal. The DP view of the carpus shows incomplete ossification of the carpal bones. (B) The LM view of the tarsus shows inadequate ossification especially of the third and the central tarsal bones. RF, Right front; RH, right hind.
Mention the 4 classifications of cuboidal ossification
Grade 1: Some cuboidal bones of the carpus and tarsus have no evidence of ossification.
Grade 2: All cuboidal bones (carpus and tarsus) have some evidence of ossification. The proximal physes of the MCIII/MTIII are open.
Grade 3: All cuboidal bones (carpus and tarsus) are ossified, but small and rounded edges are present. Joint spaces are wide and the lateral styloid process and malleoli are distinctly visible. Proximal physes of MCIII/MTIII are closed.
Grade 4: All criteria of grade 3 are met. Cuboidal bones are shaped like corresponding adult bones and joint spaces have the expected width.
Foals with incomplete ossification of the tarsal bones and greater than ___% collapse of the third and central tarsal bones have been shown to have a poorer outcome
Foals with incomplete ossification of the tarsal bones and greater than 30% collapse of the third and central tarsal bones have been shown to have a poorer outcome
Foals with straight limbs and incomplete ossification should be managed with
stall res and exercise restriction until complete ossification has occured
In case of incomplete ossification and stall rest the radiographs should be repeated every ___ weeks
2 weeks
If the foal has incomplete ossification and not straight limb the treatment should be
stall rest and restricted exercise along with external coaptation to ensure axial alignement of the joint
if you have to apply splint or casts it is important that they end at the
fetlock whenever possible to abvoid that flexor and extenor units are waken resulting in a dropped fetlock and osteopeni
when should be the splints and casts changed in foals?
splints every 3 to 4 days and casts every 10 to 14 dyas with radiographs obtained every 2 weeks to check the progress of the ossification
whcich two muscle when immobilized with casts or splint become flacid?
flexor carpi ulnaris
ulnaris lateralis muscle
“bakc-at-knee” may result from what?
While the limb is under a cast or splint, the flexor carpi ulnaris and the ulnaris lateralis muscles are immobilized and always become flaccid. This results in a temporary “back-at-the-knee” conformation immediately after splints or casts are removed
if radiographs demonstrate tha the deformity is lobated within the distal raidus or tibia and not cause by laxity of periarticular supporing sructures the splint or casts are indicated?
no, they are contra-indicated
what is the deifinition of windstep?
foals that suffer of one limb with varus deformity and other with valgus deformity (Fig 87-6)
periarticular laxity is treated how?
Such foals should be managed with controlled exercised daily for 10 to 20 minutes by walking the mare, to stimulate strengthening of the muscles and involved soft tissue structures.
Figure 87-6. (A) Image of a 1-week-old foal with a marked valgus deformity of the right tarsus (white arrow) and a varus deformity of the left tarsal region (black arrow). The degree of ossification was normal. (B) After 2 weeks of light hand-walking and no treatment, the deviations had corrected.
are periarticular laxity a very bad issue?
Cases with periarticular laxity are usually self-limiting and growth of the foal usually resolves the problem.
Figure 87-7. (A) DP radiograph of the distal limb in a 2-day-old Warmblood foal suffering from a marked varus deformity in the distal MTIII. Note the triangular shape of the epiphysis. (B) The same foal after 2 weeks of stall rest. The deformity is partially corrected because of the development of a compensatory deformity in the proximal phalanx. (C) DP radiographic view of severely deformed MTIII in a 1-week-old Thoroughbred foal. Note the rotational deformity of the distal half relative to the proximal half of the bone.
What is the rapid growth of proximal P1?
0-2 months
when does the physis closure in the proximal P1
12 months
when does the distal metacarpus metatarsus rapid growth period?
0-2 months
when does the metacarpus/metatarsus physis is closed?
6 months
when does the distal radius rapid growth period?
0-6 months
when does the distal radius is closed?
22-36 months
when does the distal tibia physis is closed?
17-24 months
when does the distal tibial rapid growth period?
0-4 months
whe does the ossificiation of foals starts and when does it stops?
it starts approximately 2 months before birth and stops 1 months after birth
5 to 7 degree deformity can be normal until ____ months of age in carpus
4 months
The vast majority of longitudinal growth in the long bones occurs in the ____________(bone) region of the physis
The vast majority of longitudinal growth in the long bones occurs in the metaphyseal region of the physis
Developmental factors, which are strongly associated with ALDs include
genetic predisposition,
dietary imbalances,
trauma,
exercise,
physeal dysplasia,
physeal overload,
and heavy birth weight
Fracture of the physes that can cause local retardation of growth at the medial or lateral aspect of the bone are classified as Salter-Harris type ____
This type of injury has been classified as a Salter-Harris type V fracture
Carpal deviations up to ___degrees are considered normal
Carpal deviations up to 4 degrees are considered normal
Long pasterns increased the odds of a fracture in the forelimb and a certain degree of carpal ________ deformity exhibited a protective mechanism
and a certain degree of carpal valgus deformity exhibited a protective mechanism
The more heavily loaded side of a bone (concave side) will grow ____ and the less heavily loaded side will grow slower (convex side).
the more heavily loaded side of a bone (concave side) will grow faster and the less heavily loaded side will grow slower (convex side).
Foals with ALDs because of disproportionate growth at the level of the physis (greater than 10 degrees) treatment
should be stall rested and exercised in a controlled fashion. Stall rest may be continued for 4 to 6 weeks. If correction does not occur during that time, a more aggressive approach should be implemented.
The solar surface should be enlarged by carefully rasping the ____
The solar surface should be enlarged by carefully rasping the heel
In valgus deformities, the ________hoof wall is lowered and in varus deformities and pigeon-toe conformation, the _______ hoof wall is lowered.
In valgus deformities, the outside hoof wall is lowered and in varus deformities and pigeon-toe conformation, the inside hoof wall is lowered.
For valgus deformities, extensions are placed on the _______ side and for varus deformities, on the_______side.
For valgus deformities, extensions are placed on the medial side and for varus deformities, on the lateral side.
Growth acceleration surgery should be performed when the foal has not corrected spontaneously by itself by
4week os age - unless >10 degrees
periosteal transection has its effect for approximately ____ months
2 monhts
A prolonged effect is achieved through surgical excision of ____________ triangular flaps
Does overcorrection of the deformity occur with hemicircumeferential periosteal transection and elevation (HCPTE)?
Overcorrection of the deformity does not occur.
What is the prognosis for HCPTE?
Good
HCPTE is performed on the concave aspect of the limb which is _________ side in a valgus deformity and ________ side in a varus deformity).
HCPTE is performed on the concave aspect of the limb (lateral side in a valgus deformity and medial side in a varus deformity).
what is the principle behind HCPTE?
The initial principle behind the procedure was reducing the static compression in the area of the physis allowing cells to accelerate their growth.
Mention in detail the surgical proceedure for correction of valgus deformity in the distal radius
a 3-cm vertical skin incision, continued through the periosteum between the common and lateral digital extensor tendons, is made 4 to 5 cm proximal to the distal radial physis and continued proximally (Figure 87-9, A). (Note: for correction of a varus deformity, the procedure is performed at the medial aspect of the bone.) The subcutaneous tissues and tendons are separated from the periosteum at the distal aspect of the incision parallel to the physis using curved hemostatic forceps. Using a curved scalpel blade (No. 12), an inverted T-shaped incision is made into the periosteum, whereby the horizontal bar of the inverted T is made 2 to 4 cm proximal to and parallel to the physis. The rudimentary ulna is transected. Once the inverted T is made The periosteal elevator is advanced at a 45-degree angle to the periosteal incisions underneath the periosteum to elevate two triangular flaps. Subxtu simple continuous USP 2-. absorbable followed by simple continuous
Figure 87-8. Foal with a varus deformity of the MMTP region with a lateral extension (Dallmer Shoe) view from the lateral (A) and from the plantar (B) aspect.
Figure 87-9. Locations at which growth acceleration may be carried out. In each location, the T incision together with the elevated triangular flaps is shown. (A) Anatomical landmarks for the surgical approach at the distal carpus. a, common digital extensor tendon; b, lateral digital extensor tendon; c, abductor pollicis longus; d, distal radial physis; e, transected rudimentary ulna.
Figure 87-9. Locations at which growth acceleration may be carried out. In each location, the T incision together with the elevated triangular flaps is shown. (B) Anatomical landmarks for the surgical approach at the distal MCIII/MTIII (A), and proximal phalanx (P1) (B). a, common digital extensor tendon and lateral to it the lateral digital extensor tendon; b, distal end of MCII/MTII; c, distal physis of MCIII/MTIII; d, extensor branch of suspensory ligament; e, proximal epiphysis of the P1; f, oblique distal sesamoidean ligaments. (
Figure 87-9. Locations at which growth acceleration may be carried out. In each location, the T incision together with the elevated triangular flaps is shown. (C) Anatomical landmarks for the surgical approach at the distal tibia. a, distal physis of the tibia; b, long digital extensor tendon; c, lateral digital extensor tendon; d, vertical periosteal incision caudal to the lateral digital extensor tendon is an alternate site (dotted line).
Figure 87-9. Locations at which growth acceleration may be carried out. In each location, the T incision together with the elevated triangular flaps is shown. (D) Location of the procedure carried out over the total length of the MCIII/MTIII. a, common/long digital extensor tendon; b, proximal aspect of the MCII/MTII. The procedure was performed and the two periosteal (barn-door) flaps were elevated.
Why bleeding can occur while transecting the periosteum in distal radius?
connected. Because this transection severs the rete carpi volaris, bleeding can occur
In about 20% of foals, the rudimentary ulna is ossified and has to be removed with
rongeurs
Why is important to transect the rudimentary ulna?
It is important to transect the rudimentary ulna, because it can act as a tethering mechanism and slow down growth at the concave aspect of the radius
What is the postop care of distal radius valgus deformity surgical correction?
Change bandages postop 3 days after and new bandage is keep for another week. At 2 weeks postop minimal exercise is done during this time
Figure 87-10. Dorsoplantar radiograph of the MTP region of a foal with a relatively straight limb. The proximal phalanx and distal MTIII have opposing deformities, resulting in an oblique orientation of the joint surface relative to the ground.
Figure 87-11. (A) Craniocaudal/dorsopalmar radiographic view of a 2-month-old Warmblood foal with bench-knee conformation. The bisecting lines drawn along the bone axes show the composition of the different deformities, distal radial valgus and MCIII varus deformity. (B) Composite radiographic view 2 months following HCPTE at the lateral aspect of the distal radius and medial aspect of the distal MCIII. A slight compensatory deformity developed in the proximal phalanx.
Figure 87-12. Transcutaneous periosteal transection technique. The skin over the distal medial MCIII is rolled with the thumb palmarly. The pointed scalpel blade is inserted through the skin down onto the bone surface, and both the scalpel and skin are pulled in a dorsal direction. This technique allows a horizontal transection of the metaphyseal periosteum and afferent physeal vessels through a 1- to 2-mm skin incision that does not have to be sutured.
What are the distal MCIII/MTIII and proximal P landamarks for periosteal transection?
The landmarks for periosteal transection at the distal MCIII/MTIII are the concave, distal most aspect of the metaphysis of the MCIII/MTIII (see Figure 87-9, B)
What structure may be inadvertly entered during the procedure of MCIIII/MTIII
Care should be taken not to enter the palmar/plantar pouch of the MCP/MTP joint.
Distal MCIII/MTIII and proximal P must be performed before what age?
months of age because after there is only limited growth of the distal physis of MCIII/MTIII
Prolonged abnormal loading of the MCP joint leads to the development of compensatory deformities in
P
Describe surgical surgery at theP
Surgery at the P1 should be carried out at the level where the extensor branch of the suspensory ligament curves over the lateral or medial aspect of the bone (see Figure 87-9, B). On this bone, the periosteal incisions are T-shaped, with the horizontal incision about 1 cm distal to the physis and the vertical incision in a distal direction. At the palmar or plantar aspect of the horizontal incision, some attachments of the oblique distal sesamoidean ligaments will be transected.
How does a typical foal with deformitie of MCP walks?
limb may appear to be straight, but when the foal walks, an outward rotation is noted. This is caused by the orientation of the articular surfaces, which are not parallel to the ground (Figure 87-10).
Bench knees
These conformational defects are the result of two opposing ALDs which ones?
valgus deformity at distal radius and a varus deformity of the proximal third of MCIII (Figure 87-11, A)
Bench knees if diagnosed within the first __ months of life can be successfully treated with periosteal transection at the distal lateral aspect of the radius and the medial aspect of the distal MCIII metaphysis (see Figure 87-9, B).
If this conformational defect is diagnosed within the first 2 months of life, the deformities can be successfully treated with periosteal transection at the distal lateral aspect of the radius and the medial aspect of the distal MCIII metaphysis (see Figure 87-9, B)
Instead of distal radius periosteal transection and medial aspect of distal MCIII metaphysis what other procedure can be perfomed?
Periosteal stripping over the total length of MCIII/MTIII using an I-shaped incision (see Figure 87-9, D) is also effective in correcting diaphyseal or metaphyseal deformities of that bone in foals younger than 2 months.
What is the modification of technique over distal medial MCIII with skin rolled?
The skin proximal to the physis is rolled caudally and the tip of the No. 12 scalpel blade is pressed down to the bone (through the periosteum) approximately 2 to 3 cm proximal to the physis. Subsequently the scalpel blade is pulled horizontally, parallel to the physis in cranial direction while simultaneously unrolling the skin (Figure 87-12). This achieves a horizontal periosteal transection through a simple puncture wound in the skin. In most cases, no sutures are needed.
The distal tibial surgical approach is either cranial or caudal to the
lateral digital extensor tendon (Fig 87-9 C)
The periosteum in the tibia is the same or is more thicken than distal radius?
The periosteum is usually thicker than at the distal radius, distal MCII/MTIII and proximal P1.
Describe surgical procedure of periosteal stripping in the tibia
3 cm vertical skin incision continued through the periosteum cranial or caudal to the lateral digital extensor tendon - 4 to 5 cm proximal to the distal tibial physis and is continued proximally
Name the techniques of growth retardation
Implants in the convex aspect:
staples - not used anymores
screws and wires
single transphyseal screw
2.7 mm bone plate in older foals
What are the 2 types of candidates for growth retardation?
- Growth retardation is performed either in young foals (<3 months of age) with severe ALD
- or in foals with significant ALD in a bone after the rapid growth phase is over (MCIII/MTIII and P1 after 2 months, tibia after 4 months, radius after 6 months).
How do you perform insertion of screws and wires for growth retardation?
Implants are inserted through two stab incisions, one in the center of the epiphysis and the other proximal to the physis (Figure 87-13, A). The soft tissues between these incisions are elevated with a hemostat (see Figure 87-13, B). A 4.5-mm cortex screw is inserted through each incision but not completely seated (see Figure 87-13, C). A wire loop is inserted through the proximal ABECincision and hooked over the distal screw head (see Figure 87-13, D). The two wire ends are twisted together and tightened over the proximal screw head (see Figure 87-13, E). The stab incisions are then closed with two simple-interrupted skin sutures, and the area is protected with a light bandage for approximately
10 days.
Why twisting the wire around screws is preferable in the proximal screw?
Twisting the wire ends over the proximal screw rather than the distal screw results in less irritation of the surrounding soft tissues and produces a better cosmetic result.
Which situations the screw and wire technique is applied?
- valgus in distal radius
- distal valgus of MCIII/MTIII
- distal valgus in proximal P1
- distal valgus in proximal tibia
Figure 87-13. Growth retardation. (A) A stab incision to the bone is carried out at the convex aspect of the epiphysis and the distal metaphysis. (B) The soft tissue between the two incisions is elevated. (C) A 4.5-mm cortex screw is implanted through each incision but not tightened. (D) A cerclage wire loop is introduced through the proximal incision, hooked over the distal screw head, and tightened in figure-of-eight fashion over the proximal screw (E). The screws are subsequently completely inserted, which increases wire tension as the wires ride up on the shoulder of the screw heads.
The single transphyseal screw description of technique
The foal is placed in dorsal recumbency and the limb secured in an extended vertical position. A 10-mm stab incision is made 10 to 12 mm proximal to the physis through the skin, subcutaneous tissue, and periosteum. The periosteum is elevated for 5 mm on either side of the incision. A 4.5-mm cortex screw is inserted through a stab incision using a position screw technique from the metaphysis across the physis into the epiphysis under radiographic/fluoroscopic guidance. The screw should be placed to ensure as much perpendicular crossing of the physis as possible and care is taken not to cross the middle of the physis but to stay in its outer fourth. The 3.2-mm drill sleeve is angled at 70 degrees to the physis and a 3.2-mm drill bit is used to create a hole. Countersinking. Following countersinking, the hole is measured with the depth gauge and subsequently hand tapped and a 4.5-mm cortical bone screw is inserted.
Why in insertion of the single transphyseal screw is important countersink
Countersinking is important to maintain a normal contour of the limb and to prevent the screw head from bending when tightening the scre
Why in insertion of the single transphyseal screw countersink is not advised in THO?
Thoroughbreds, countersinking is discouraged because it will eventually leave a scar following screw removal, which can be detected later on prepurchase radiographs
In single transphyseal screw to prevent the 3.2-mm drill sleeve and bit from slipping off the bone when starting to drill, a shallow hole is created beforehand using a ____mm drill bit aiming parallel to the physis.
To prevent the 3.2-mm drill sleeve and bit from slipping off the bone when starting to drill, a shallow hole is created beforehand using a 5.5-mm drill bit aiming parallel to the physis.
The major application for single transphyseal screws is in which situations?
The major application for single transphyseal screws is the distal MCIII/MTIII, (Figure 87-15) a single transphyseal screw also may be used in the distal radial and tibial physis (Figure 87-16).
what are the advantages of single transphyseal screw technique?
are ease of insertion and improved cosmesis. The screws are removed when the desired correction is achieved.
Good results were achieved using a single transphyseal screw at the distal MCIII/MTIII physis implanted at an average age of _____days, leaving the implant in place for an average of ___ days
Good results were achieved using a single transphyseal screw at the distal MCIII/MTIII physis implanted at an average age of 112 days, leaving the implant in place for an average of 31 days
The single screw was found to be an effective technique in foals aged up to ____ months of age
The single screw was found to be an effective technique in foals aged up to 5 months of age
What is a common complication when screw is applied int eh distal radius and tibia?
Some caution is indicated when the screw is applied in the distal radius and tibia, because of the potential development of a physitis and metaphyseal collapse
Why the common complication in distal tiba and radius is not so common on MCIII and MTIII disal physes?
because MCIII and MTIII physes close earlied (approximatelly 4 months)
Figure 87-16. (A) Foal with a severe carpus valgus deformity of the right forelimb. (B) Preoperative DP radiograph of the right carpus showing the valgus deformity. (C) Immediate postoperative radiograph showing a single transphyseal screw inserted on the medial aspect of the distal radius in an oblique proximodistal direction across the distal radial physis. (
What is the primary advantage of the single transphyseal screw technique?
It offers faster correction due to static fixation.
What potential issue arises when using two screws and a wire for correction?
A lag phase in angular correction may occur, needing growth for compression.
What complication may be linked to wire usage in surgery?
Wire breakage can delay correction.
What size bone plate is suggested for correcting ALD in older foals?
A 2.7-mm four- to five-hole bone plate.
How many holes on each end of the bone plate need to be enlarged?
The last hole on each end.
What kind of incision is made for the surgical approach?
A slightly curved incision centered over the physis or a stab incision.
What is the purpose of drilling a hole into the physis during surgery?
To insert a screw that achieves compression during surgery.
What is the recommended diameter for the screws used with the bone plate?
3.5 mm screws
Why is it crucial to tighten the distal screw completely?
To prevent protrusion into the collateral ligament.
What is the benefit of using implants in growth procedures?
They can remain in place as long as needed, unlike periosteal transection.
What alternative approach uses a radial shock wave generator?
Local growth retardation to treat angular limb deformities.
What is the median time for straightening limbs treated with shock wave therapy?
25 days
Why is early recognition of ALD important in Miniature Horses?
They have less growth potential than regular horses.
What is a significant anatomical feature causing ALD in Miniature Horses?
The presence of complete ulnas and fibulas.
What surgical intervention might be necessary to correct fibular movement?
Transfixation of the distal fibular styloid process.
When should the implants ideally be removed post-surgery?
Before complete limb straightening (at 85%-95% correction).
How is implant removal typically performed?
Through stab incisions over the screw heads.
What challenges can arise during screw removal?
New bone formation may complicate access to the screw head.
Why must the screwdriver seat correctly in the screw head?
To prevent stripping the screw head, making removal difficult.
What percentage of foals achieved total limb straightening with HCPTE?
81.5%
What major complication followed HCPTE in a foal?
Sepsis of the common extensor tendon
What increases the risk of complications post-implants removal?
More tissue trauma during screw localization.
What was identified as a rare but possible surgical complication?
surgical site infection
Which technique was associated with a higher risk of physitis?
The single transphyseal screw technique.
What was the outcome associated with using the two-screw-tension band wire loop technique?
Fewer complications (7.5% physitis).
What correlation was highlighted regarding the location of the pivot point in carpal deformities?
More distal locations lead to poorer prognoses.
What does the text indicate about the long-term performance of treated foals?
Racing performance was lower in treated foals compared to untreated siblings.
What must be monitored post-surgery to prevent overcorrection?
Frequent examinations and radiographic evaluations.
Why is it crucial not to wait for both limbs to straighten before removing implants?
It can lead to overcorrection in one limb or undercorrection in another.
What should be done if septic physitis occurs post-surgery?
Close monitoring and possibly quick implant removal if necessary.
What types of ostectomy/osteotomy are described?
1) Step ostectomy in the sagittal plane,
2) step osteotomy in the frontal plane,
3) closing wedge ostectomy.
When are closing wedge ostectomies typically used
For correction of diaphyseal and metaphyseal/epiphyseal ALDs in foals with closed growth plates.
What are the main advantages of a step ostectomy/osteotomy over a closing wedge ostectomy?
Maintenance of bone length and the ability to achieve good interfragmentary compression.
What structure is split longitudinally during the procedure?
The lateral digital extensor tendon along with the periosteum.
What does the skin incision for a sagittal step ostectomy target?
It extends from the top of the MCIII/MTIII to the distal physis, then to the MCP joint.
What is done to the periosteum at the planned osteotomy site?
It is elevated circumferentially around the bone.
How is the pivot point for the osteotomy determined?
By drawing longitudinal bisecting lines through MCIII/MTIII and the phalanges on radiographs.
What is the significance of drilling holes through the cannon bone?
They guide the oscillating saw cut across the bone in a sagittal plane.
What shape is the osteotomy performed in a step ostectomy?
Z-shaped osteotomy.
What is the purpose of the aluminum template during the procedure?
To guide the angle of the wedge to be removed.
What should be ensured during final adjustments post-osteotomy?
Complete correction of the deformity and bone-on-bone contact at the palmar/plantar aspect.
How can additional rotational deformities be corrected?
By removing an additional bone wedge from the appropriate aspect of the bone.
How can additional rotational deformities be corrected?
By removing an additional bone wedge from the appropriate aspect of the bone.
What is applied across the vertical section of the cut to reunite the fragments?
Cortex screws in lag fashion.
What follows after the reapposition of bone fragments?
A bone plate is applied either medially or laterally, depending on the deformity.
What is done with the gap remaining after wedge removal?
It may be filled with some bone from the removed wedge as a cortical bone graft.
What postoperative support is suggested for the limb?
Bandaging and splinting or casting for a few weeks.
What is the typical difficulty in performing the step osteotomy in the frontal plane?
The saw cuts are more challenging compared to sagittal techniques.
What is the primary purpose of determining the angle of deviation from radiographs?
To establish the size of the wedge ostectomy needed for correction.
What kind of plates can be used for internal fixation in osteotomies?
One or two bone plates based on the size of the foal.
How is the ostectomy site marked for rotational orientation
A longitudinal periosteal incision is made.
What is essential to achieve after transecting the MCIII/MTIII?
Reapposition of the transected long bone segments at their cut surfaces.
What bones are most frequently targeted for step ostectomies/osteotomies?
MCIII and MTIII.
In which other bones can these procedures be performed if necessary?
In selected cases, they can be performed on P1 or the radius.
What is the overall prognosis for athletic activity post-procedure?
The prognosis is considered guarded to fair.
What should be taken into account regarding complications?
All complications associated with open reduction and internal fixation in horses.
What is the post-surgical recommendation if the procedure is carried out near the physis?
Special bone plates may be needed due to limited room for engaging screws.
What are the primary goals of corrective osteotomy/ostectomy?
To correct angular limb deformities and restore alignment.
How is the rotational alignment restored after bone transection?
Using the longitudinal cut in the periosteum.
What happens to the lateral and medial cortices during wedge ostectomy?
They are marked and then transected based on the determined wedge size.
Why is careful planning essential before performing an ostectomy?
To ensure proper correction of angular deformities and prevent complications.
Figure 87-17. (A) Foal with a bilateral valgus deformity of the tarsus. (B) Preoperative DP radiograph of the right tarsus showing the valgus deformity. (C) Postoperative radiograph of the right tarsus showing a four-hole 3.5-mm plate applied to the medial aspect of the distal tibia with two 3.5-mm cortex screws to retard growth. When using the bone plate technique at the distal radius, the distal screw does not cross the physis but only at the distal tibia to prevent intraarticular screw insertion secondary to the undulating shape of the distal tibial epiphysis.
Figure 87-19. (A) A 5-month-old Miniature Horse with severe tarsal valgus deformities in both hind limbs. A DP radiograph of the left carpus shows a completely developed ulna (B), and a DP view of the left tibia shows a completely developed fibula (C). Note the acute angle of the lateral trochlear ridge of talus, representing early degenerative changes (arrow).
Figure 87-20. (A) Closing wedge ostectomy. The bone wedge is removed from the horizontal plane near the physeal region. (B) Step ostectomy. The wedge is removed from the center of MCIII in the sagittal plane. (C) Derotational step ostectomy. By removing a vertical wedge with its wide aspect located either dorsally or palmarly, a rotational deformity can be corrected. (D) Step osteotomy. The Z-plasty is performed in the frontal plane, and the fragments are rotated into alignment.
Schweinsberg et al 2021 What are the primary etiological factors involved in bone deformities, and which specific factors contribute to long-bone misalignment?
Bone deformities are caused by genetic, perinatal, and developmental factors, including aberrant ossification, periarticular laxity, dietary imbalances, overload, trauma, infection, and fracture malunion.
Schweinsberg et al 2021 How does the single-cut osteotomy differ from a wedge ostectomy in terms of procedural technique and outcomes?
A single-cut osteotomy requires only one cut, preserving more bone contact for stable fixation and faster healing, while wedge ostectomies involve multiple cuts, increasing the risk of inaccuracies and bone weakening.
Schweinsberg et al 2021 Why was computed tomography (CT) preferred over radiographic imaging for deformity assessment and presurgical planning in this case?
CT provides a more accurate three-dimensional view, essential for measuring complex deformities like combined angular and torsional deviations, which can be challenging to assess with radiographs alone.
Schweinsberg et al 2021 What is the purpose of using a 3D model in planning a single-cut osteotomy for complex deformities, and what role did the undeformed contralateral bone play in this case?
The 3D model aids in simulating the osteotomy and verifying corrections before surgery, while the undeformed contralateral bone serves as a template for accurate deformity replication and comparison.
Schweinsberg et al 2021 What limitations were identified in this case regarding the use of single-cut osteotomies in equine patients, and what future improvements were suggested?
Limitations include potential inaccuracies in angle measurement, lack of validated techniques, and challenges in larger animals. Future improvements include creating 3D cutting guides tailored to the deformity for increased precision.
