Chapter 93 - part 1 condylar fx Flashcards
What is the function of the MCII and MTII bones in horses?
They serve major weight-bearing functions
How does the cross-section of MCIII change in horses?
It dramatically changes in response to increased loading as the horse ages and trains
What makes the great metatarsal (dorsal MTIII) artery particularly vulnerable in horses?
Its location between MTIII and MTIV
Where is the most common site of major fracture in MCIII/MTIII bones in athletic horses?
In the distal articulation
In the forelimb the major neurovascular structures course along the length of MCIII both medially and laterally dorsal to the flexor tendons but in the hindlimb the artery courses
laterally between MTIII and MTIV
Repetitive loading during intensive exercise
leads to focal accumulated injury in the
parasagittal groove region that can eventually result in complete fracture
Vertical fractures in the sagittal plane occur in the
distal condyle of MCIII/MTIII
In which group of horses are lateral condylar fractures most common?
Young racehorses
Which limb is more likely to be affected by** lateral condylar fractures in Thoroughbred**s?
Forelimb
What is a typical clinical sign of a lateral condylar fracture in horses?
Acute onset of severe lameness after intense exercise
What percentage of condylar fractures involve the lateral condyle?
Around 85%
In complete displaced fractures of the third MC/MT are displaced by the MCP/MTP joint flexion and reduced extension what is contraindicated in the immobilization?
All immobilization
techniques should therefore include extension; any
that involve flexion are contraindicated.
How do lateral condylar fractures typically propagate?
In a sagittal plane then spiral to oblique/frontal planes
What advanced imaging techniques are increasingly diagnosing unicortical condylar fractures?
CT and MRI
Figure 7.7 Digital pressure applied dorsoproximally frequently
elicits a painful response in horses with non-or
minimally
displaced sagittal/parasagittal fractures of the proximal phalanx.
Complete fractures disarm the_____________ _______________
ligament of the MCP/MTP joint leading to instability and
potential creation of an open fracture or disruption of the
proximal scutum
Complete fractures disarm the** lateral collateral
ligament of the MCP/MTP joint** leading to instability and
potential creation of an open fracture or disruption of the
proximal scutum
What are the immobilization that should be considered for MC/MT condylar fractures?
Compression boot in the FORELIMBS
Robert Jones bandage for incomplete, with medially and laterally splinted up to the level of thirc carpal or third/fourth tarsal bones
Robert Jones bandages, or a bandage cast for complete fractures.
In the absence of a compression boot, these techniques are also appropriate for forelimbs
What is the main difference of the medial condylar fracture in the immobilization comparing to LAT?
First aid and coaptation for medial condylar fractures does not differ much from lateral fractures with one major exception: horses with medial condylar fractures in the hindlimb should be crosstied until surgery is performed.
Figure 7.18 Construction of a splinted Robert Jones bandage for the distal hindlimb. (a) Splints should be positioned medially and
laterally in contact with the widest point of the hoof from the bearing surface to the level of the third (medially) and fourth (laterally) tarsal bones. The lateral splint is often longer in consequence. Sufficient cotton wool is added to fill the space between limb and splints. Minimal bandage material is applied at the level of the hoof to maintain the hoof/splint interaction. (b) Splint alignment is maintained by application of inelastic tape to prevent twisting or rotation while enclosing elasticated tape is applied. (c and d) The completed splinted bandage.
what is this?
Figure 7.20 Newmarket Compression Boot. Readily applied, radiolucent and rigid construct. The design enables the horse to load the limb in a normal position.
What if it is a diaphyseal fracture of the third metacarpal/metatarsal bone?
marked bending forces, and complete fractures are inherently
unstable even if not displaced. Casts provide the only
contributory support.
The medial condyle is ______in both mediolateral and dorsopalmar/plantar (DP) planes.
The medial condyle is larger in both mediolateral and dorsopalmar/plantar
(DP) planes.
Growth plate closure in MCIII and MTIII is…
Complete closure of the growth plate occurs between 10 and 18 months with radiographic, which is generally thought to
represent functional, closure between six and eight
months
Fractures are generally classified from radiographic features
(Figure 21.1). They may be unicortical (although
this usually involves pa/pl subchondral compacta rather
than cortical bone) or** bicortical. Fractures are classified
as complete if the fractures in dorsal and pa/pl cortices conjoin to exit through the periosteal surface of the metaphysis
or diaphysis of the bone and incomplete if this has
not occurred. Displacement has been variously and
inconsistently defined. The author’s favoured definition
is that displacement involves a change in the anatomic
axis of one fragment with respect to another. In distraction,
orientation is maintained and fragments simply
separate. Displacement can involve abaxial, proximodistal,
DP or rotational movement; frequently, there is a
combination of these. In some fractures, this can only be
determined arthroscopical. Incomplete fractures can distract at the articular surface but cannot displace. Fractures that extend into the diaphysis are described as propagating. These are of
two types. The first remain in a sagittal or parasagittal**
plane, and the second begin in this plane and then change
orientation to oblique or frontal planes; the latter are
generally referred to as** spiral**
Propagating fractures are much more common____________ (medially /laterally)
Propagating
fractures are much more common medially than laterally, almost invariably commence immediately adjacent to the sagittal ridge
Fractures that commence axially
whether medial or lateral are usually __________(longer/shorter) than those
which arise abaxially
Fractures that commence axially
whether medial or lateral are usually longer than those
which arise abaxially
Fractures of the lateral condyle are usually easier or more complex?
Fractures of the** lateral condyle also feature in complex
usually catastrophic fractures **centred on the MCP/MTP
joint.
These generally manifest as racing injuries and commonly
include a displaced fracture of the lateral condyle,
proximal sesamoid fractures and markedly comminuted
fracture of the proximal phalanx.
Figure 21.1 Fractures of Mc3/Mt3 condyles imaged by transverse (a) and reconstructed 3D (b)–(g) CT. (a) Short palmar ‘unicortical’
fracture of the lateral condyle. (b) Bicortical incomplete fracture of the lateral condyle. (c) Complete non-displaced
fracture of the
lateral condyle. (d) Displaced fracture of the lateral condyle. (e) Parasagittal propagating fracture of the medial condyle. (f) ‘Spiral’ propagating fracture of the lateral condyle. (g) ‘Spiral’ propagating fracture of the medial condyle.
When using combined data from comparable UK and USA studies, 220 of 298 (74%) fractures in the UK and 391 of 455 (86%) fractures in the USA were
____________(lat or med).
When
using combined data from comparable UK [18, 21] and
USA [25, 26, 55–57] studies, 220 of 298 **(74%) fractures in
the UK and 391 of 455 (86%) **fractures in the USA were
lateral.
What imaging technique is commonly used to diagnose unicortical condylar fractures?
MRI
Studies revealed that propagation is more common in medial or lateral condylar fractures?
Propagation was identified in 28 of
35** (80%) medial** and 12 of 139 (9%) lateral fractures
Name the types of features and presentation of condylar MC/MTIII fractures
- Palmar/Plantar subchondral bone (unicortical incomplete)
- Bicortical incomplete
- Bicortical Complete non displaced
- Bicortical Complete displaced
- Propagating/spiral
- Complex/comminuted
Fracture of the condyle usually has as symptoms
Lameness preeceding the onset of a more severe lameness
short choppy gait if bilateral
MCP/MTP effusion
Pain over manipulation
LAMENESS NOT CORRELATED with amount of fracture displacement
What are the radiographic views ideal for visualization of the fracture in unicortical palm/plantar subchondral bonel?
horizontal beam Dorsal 35º distal pal/pl proximal oblique
Flexed horizontal beam DP view
Fractures of the MC or MT condyles may be unicortical if they involve
palmar/plantar subchondral
bone
Palm/Plantar subchondral fractures are many times silent in radiograph for how long?
frequently radiographically silent for
7–10 days and sometimes for 2–4 weeks
Non displaced condylar fractures are treated how?
can be arthroscopically assisted or standing without arthro with placement of cortex screws through stab incisions
1st screw in the epicondylar fossa
What is the common location for the propagation of lateral condylar fractures?
Proximolaterally toward the lateral cortex
From the mid- to midaxial portion of the lateral condyle, sagittally, then proximolaterally
What does fracture classification indicate about prognosis?
Nondisplaced fractures have a better prognosis than displaced fractures
Lateral condylar fractures are oriented vertically, occur in the sagittal plane, and range from faint, short linear cracks to complete displaced fractures with extensive comminution.
Figure 93-2. For preoperative evaluation of the distal palmar/plantar surface of MCIII/MTIII, a dorsal 120-degree proximal–palmar/plantar distal oblique (A and B) or a flexed horizontal beam DP view (C and D) should be taken. Arrows indicate typical appearance of comminution along that margin that may be very difficult to see on a standard DP projection.
Figure 93-3. (A) A robotic cone beam computed tomography (CBCT) unit being used to obtain computed tomographic images of a metatarsophalangeal joint in a standing horse. Transverse (B), frontal (C), and sagittal (D) CT images of a horse with a left front medial condylar fracture obtained using the robotic CBCT.
Name the type of condylar fractures
What is an incomplete fracture?
An incomplete fracture is defined as one that originates in one cortex or subchondral bone plate, but has no apparent fracture line perforating the opposite cortex or distant subchondral bone plate so SAME AS UNICORTICAL (NIXON)
What is a complete fracture?
Complete fractures represent full cis‐ and transcortical discontinuity, but may be further subdivided into stable
or unstable fractures, since this state affects the repair methods and prognosi (NIXON)
Unstable fractures meaning and when should they be repaired?
Unstable fractures have little or no remaining cortical continuity to prevent axial, rotational, and bending motion. Unstable fractures not only carry a poorer prognosis for repair due to their inherent instability, but also need to be repaired without delay to prevent continued damage (NIXON)
Palm/Plantar suchondral fractures are usually lateral or medial?
71% lateral with no difference to FL or HL
which imaging tx is the best to diagnose palm/plantar subchondral plate fractures?
MRI
Figure 21.2 Fracture of the medial palmar subchondral bone and adjacent dense epiphyseal spongiosa. (a) Transverse CT image at the level of the base of the proximal sesamoid bones (with the MCP at a neutral angle). Fracture (arrow) identified in flexed (b) and standard (c) DP radiographs.
MC
Figure 21.4 Short bicortical fracture of the lateral condyle of Mc3. (a) DP radiograph demonstrating an abaxial fracture course. (b) Fracture
location in a transverse CT image at the level of the epicondylar fossa.
Figure 21.5 Long incomplete fracture of the lateral condyle of Mc3 imaged on a DP radiograph and in transverse CT images at the depicted levels (hashed lines).
Incomplete fractures can be difficult to dx on radiographs (because sometimes they are complete) what do certain authors say about size estimation to know if is complete or incomplete?
Some authors consider that fractures
that extended ≥75% of the distance from the distal
articular surface to their projected metaphyseal or
diaphyseal exit point should be considered complete
even if radiographic evidence of such is lacking
Non displaced fracuters with minimal soft tissue dissection are surgically managed with
cortex scrw fixation in lag technique using radiographs and CT and radiopaque markers
In nondisplaced fractures what is the reference for the most distal screw?
by taking the midpoint of an imaginaryline drawn between the proximal palmar/plantar prominence of P1 and the most dorsal aspect of the lateral condyle, both readily palpable landmarks.
What is the primary goal of surgical management for lateral condylar fractures?
To prevent proximal propagation and enhance articular healing
What factor often influences the decision between conservative and surgical treatment in non-displaced fractures?
B) Owner/trainer preference
How much time is the conservative box rest?
4-8wk box rest, progressive rehabprogram, training not resumed <120d
What is the most common technical error in lag screw fixation of nondisplaced condylar fractures?
Inadequate compression
Compression of the fracture is optimized if the screw is midway between the dorsal and palmar/plantar articular surfaces, and perpendicular to the bone in both proximodistal and lateromedial planes. (wright)
Which screw is most critical? What additional procedure is recommended at the time of surgery to assess fracture reduction?
The distal screw is most critical and is always placed
first. This should be positioned in the** center of the bone,
at the junction of the proximal and middle thirds of the
epicondylar fossa** and do arthroscopic examination
The lateral condylar non-displaced fractures can be surgically corrected standing under LA, what is the number of screws required?
the majority of lateral condylar fractures can be treated with two screws. A few propagate proximad enough to justify more screws but usually the more proximal portion of the fragment is quite narrow in its dorsopalmar/-plantar thickness, and accurate positioning of the screw in the center of that part of the fragment is difficult.
Placing 3 or 4th screw would have better outcome?
There is little evidence to suggest that placing a third or fourth screw in the longer fractures results in a better outcome, particularly in nondisplaced fractures.
What can prevent inadequate compression during lag screw fixation of nondisplaced condylar fractures?
Drilling the thread hole fully through the far cortex
How can incorrect aiming of the drill be minimized during surgery?
By placing the fractured bone parallel to the ground
Describe the surgical procedure step by step
Figure 9.2 Lag screw technique demonstrated on a lateral condylar fracture of the third metacarpal bone. The distal screw is already inserted. (A) the** glide hole** is drilled with the large drill bit and the double drill guide; (B) the insert portion of the double drill guide is inserted into the glide hole and the **concentric thread hole cut with the small drill bit; (C) the countersink depression **is prepared on the
surface of the near cortex; (D) the length of the screw needed is determined with the depth gauge; (E) the threads are cut in the far cortex
with the** tap through the double drill guide; and (F) a screw of the predetermined length is inserted and tightened with the hexagonal t** ipped screwdriver.
FIGURE 3 Transverse (A-C) and dorsal (D-F) plane computed tomography images of horses with linear subchondral bone injury (A,D), crescentic subchondral bone injury (B,E), and ovoid subchondral bone injury (C,F) lesions in the lateral condyle of horses with lateral condylar fractures
Figure 93-6. Arthroscopically assisted repair of a displaced lateral condylar fracture can be performed by drilling the glide hole and placing the insert drill sleeve before placing the scope. Fracture reduction is checked with the scope as the fragment is manipulated by flexion/extension/rotation of the hoof and manipulation of the fragment using the insert sleeve. Pointed reduction clamps are used to hold the fragment after reduction is achieved.
Nearly all lateral condylar fractures can be repaired with two cortex screws placed in lag fashion, one in the epicondylar fossa and the other near the physeal scar.
Figure 93-9. Axial sesamoid fractures associated with displaced lateral condylar fractures are a strong indication of major damage to the MCP joint. They can be seen on standard DP (A) and flexed DP
(B) projections. (C) If the fragment is completely separated (arrows), the best option is probably MCP arthrodesis.
Figure 93-8. Badly damaged and displaced lateral fractures are inherently less stable, and the screws are subjected to more bending loads. Both 5.5-mm screws and extra screws in the distal condyle should be considered to enhance stability. No effort is made to reconstruct the comminuted fragments at the proximal end of lateral condylar fractures.
name projection
Fig 4: a) DP and b) 20-degree DMPLO views of a 3-year-old
Thoroughbred filly with a right forelimb complete and displaced
lateral condylar fracture. This dorsopalmar projection results in the
condylar fracture line being superimposed over the axial aspect
of the lateral proximal sesamoid bone in a), preventing complete
evaluation of the axial border. The 20-degree DMPLO view
revealed a complete and displaced sagittal axial fracture of the
lateral proximal sesamoid bone (arrows). Lateral is located to the
left side of radiograph a) and b). Labbe EVE 2021
MC2
diagnosis and description
Fig 3: Axial computed tomography images of a 3-year-old Thoroughbred filly with a right forelimb complete and displaced lateral
condylar fracture and complete, comminuted, sagittal axial fracture of the lateral proximal sesamoid bone. Dorsal is to the top of the
images and lateral is to the right of the images. The approximate 20 degree medial oblique radiographic angle measurement is
demonstrated in b).
Figure 93-11. Medial condylar fractures of MTIII that have an oblique diaphyseal component (arrow) are extremely dangerous fractures, prone to catastrophic dehiscence.
Figure 93-12. Open exposure of a spiraling MTIII fracture with the fracture line (arrows) “disappearing” in the middiaphysis. The simplest method of defining the configuration of a medial condylar fracture in the diaphyseal region is to make an open approach with periosteal elevation. Implants can subsequently be placed accurately more easily.
after 2 cm incision in minimally invasive approach what do you do next?
After the subcutaneous (not subperiosteal) tunnel is made, a roughly contoured 10- or 12-hole broad 4.5/5.0-mm LC P is slid down along the bone (Figure 93-14).
The screw placement is based on what?
fracture configuration
*openlateral approach generally allows the surgeon to seethe spiral fracture as it propagates in the dorsalcortex and as the palmar component exits from the palmar/plantar cortex intothe lateral cortex *Directfracture observation enables the surgeon to insertscrews in a biomechanically optimal position along the entire length of thefracture
Figure 21.27 Intra-operative dorsal (a) and lateral (b) views of
percutaneous needles at sites of proposed screw placement for
repair of a spiral fracture of Mt3. Note distal lateromedial
orientation progressing through increasing dorsolateral to
plantaromedial oblique to dorsoplantar trajectories proximally
in line with CT determination of the fracture plane.
Figure 21.27 Intra-operative dorsal (a) and lateral (b) views of
percutaneous needles at sites of proposed screw placement for
repair of a spiral fracture of Mt3. Note distal lateromedial
orientation progressing through increasing dorsolateral to
plantaromedial oblique to dorsoplantar trajectories proximally
in line with CT determination of the fracture plane.
Figure 93-17. Plate removal is performed with the horse standing, using local anesthesia. (A) A matching plate facilitates accurate stabs over the screw heads. (B) All of the screws are partially removed. After all are loosened and counted, they are removed. (C) A nail set and a mallet can be used to loosen the plate. If necessary, the proximal end is grasped with vise grips for removal.
