Chapter 92 - part 1 middle phalanx Flashcards
Bones and joints: 1- Medial proximal sesamoid bone (palmar margin); 2- Proximal phalanx, 2a- body, 2b- medial palmar eminence; 3- Middle phalanx, 3a- body, 3b- flexor tuberosity; 4- Distal phalanx, 4a- parietal surface, 4b- solar margin, 4c- medial palmar process, 4d- lateral palmar process; 5- Distal sesamoid bone; 6- Straight sesamoidean ligament; 7- Medial oblique sesamoidean ligament; 8- Lateral oblique sesamoidean ligament; 9- Collateral ligament of the PIPJ; 10- Middle scutum; 11- Abaxial palmar ligament of the PIPJ; 12- Axial palmar ligament of the PIPJ; 13- Collateral ligament of the distal interphalangeal joint; 14- Medial collateral sesamoidean ligament; 15- Lateral collateral sesamoidean ligament; 16- Proximal sesamoidean ligament; 17- Distal sesamoidean ligament;
Tendons and associated structures: 18- Third interosseous muscle (suspensory ligament),
medial extensor branch; 19- Superficial digital flexor tendon, 19a- medial branch (cut), 19b- lateral branch (cut); 20- Deep digital flexor tendon (infrasesamoidean part); 21- Proximal attachment of the distal digital annular ligament;
Ungular cartilages: 22- Proximal attachment of the chondrocompedal ligament; 23- Medial ungular cartilage (cut); 24- Lateral ungular cartilage (cut).
MP
Removal of flexor tendons and straight sesamoidean
3- Middle phalanx, 3a- body, 3b- flexor tuberosity, 3c- condyle (palmar
margin); 4- Distal phalanx, 4a- parietal surface, 4b- solar margin, 4c- lateral palmar process,
4d- medial palmar process; 5- Distal sesamoid bone (flexor surface), 5a- sagittal crest; 6- Lateral
collateral ligament of the metacarpophalangeal joint (superficial layer); 7- Palmar (intersesamoidean)
ligament, 7a- sesamoidean part, 7b- suprasesamoidean part; 8- Lateral oblique sesamoidean
ligament; 9- Medial oblique sesamoidean ligament; 10- Intermediate sesamoidean ligament;
11- Cruciate sesamoidean ligament; 12- Collateral ligament of the PIPJ; 13- Middle scutum;
14- Abaxial palmar ligament of the PIPJ; 15- Axial palmar ligament of the PIPJ; 16- Lateral collateral
ligament of the distal interphalangeal joint; 17- Lateral collateral sesamoidean ligament;
18- Medial collateral sesamoidean ligament; 19- Proximal sesamoidean ligament;
Tendons and associated structures: 20- Lateral digital extensor tendon; 21- Third interosseous
muscle (suspensory ligament), 21a- lateral branch, 21b- lateral extensor branch; 22- Superficial
digital flexor tendon, 22a- lateral branch (cut), 22b- medial branch (cut);
Ungular cartilages: 23- Lateral ungular cartilage (cut); 24- Medial ungular cartilage (cut).
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The forelimb has four functional segments (Figure 6.1):
(i) distal to the distal portion of the metacarpus; (ii) from the distal radius to the distal metacarpus; (iii) from the elbow joint to the distal radius; and (iv) from the distal scapula to the elbow joint. In the hindlimb the functional divisions include these segments: (i) distal to the distal portion of the metatarsus; (ii) from the proximal metatarsus to the distal metatarsus; (iii) from the stifle joint to the
proximal metatarsus; and (iv) proximal to the stifle joint.
Fractures of the proximal scapula, femur, pelvis, and axial skeleton cannot be protected by e
How do you classify the fractures?
Complete or incomplete
2) Stable or unstable (nondisplaced or displaced)
3) Open or closed
4) Configuration
a) Greenstick or fissure
b) Transverse
c) Oblique
d) Spiral
e) Comminuted
f) Multiple
g) Impacted
h) Avulsion
5) Diaphyseal, metaphyseal, physeal, or epiphyseal (including
Salter–Harris physeal fractures, types I to VI)
6) Other (pathological fracture; multiple bone
involvemen
How do you immobilize a stable or unstable fracture of P2?
Bandage with dorsal splint (wedge in heels) and incorporate that in a cast and send to a hospital (Watkins video).
Nixon book a forelimb is affected, the limb
is supported off the ground by an assistant, while a lightly
padded bandage is applied extending from just distal to the coronary band to the proximal aspect of the metacarpus.
A rigid splint such as polyvinylchloride (PVC) is
taped to the dorsum of the bandage to maintain alignment of the dorsal cortices of the phalanges with the third metacarpus.
The splint and bandage, including the hoof, are then encased with fiberglass cast material. The same procedure is applied to hindlimb fractures, except the limb is
best positioned with the toe resting on a platform to achieve alignment of the dorsal cortices of the phalanges
and third metatarsus.
how do you immobilize a middle biaxial phalanx fracture with plantar disruption?
*Biaxial palmar eminence fractures: The limb should receive acute temporary immobilization of the metacarpophalangeal
or metatarsophalangeal and interphalangeal
joints in a flexed position A palmar (plantar) board splint is ideal**,(disruption of suspensory apparatus) but good reduction also can be obtained
with a Kimzey Leg Saver Splint.
In the absence of these
and in situations of reduced diagnostic confidence, a
The middle phalanx the blood supply is rich or poor in this region? What are the challenges?
Poor
Challenges –poor blood supply, continual tension, high motion, covered in ligaments
How is the middle phalanx primarily loaded during athletic activity?
Axial and torsional planes
With which bone does the middle phalanx articulate through a high-motion joint?
Distal phalanx
Where is the middle phalanx more exposed?
Proximally palmar plantar eminences
Which tendons contribute to the motion of the PIP and DIP joints?
Digital extensor and flexor tendons
common (or long) digital extensor tendons dorsally and the digital flexor tendons palmarly (or plantarly) contribute
to motion of the proximal and distal interphalangeal (PIP and DIP) joints and provide resistance to overextension of the distal limb
What stabilizes the middle phalanx laterally and medially?
Collateral ligaments of the proximal and distal interphalangeal joints
suspensory ligament of the distal sesamoid bone
palmar/plantar scutum (combo of straight sesamoidean ligament and SDFT
surrounding hoof capsule)
In what horse breeds are fractures of the middle phalanx most common?
Quarter Horses and Arabians
What type of fractures occur primarily in the hindlimbs of cutting and reining horses?
Comminuted fractures
Which type of fractures result from a mixture of axial compression and torsion?
Comminuted fractures
reining sudden stops and turns primarily in the hindlimbs
Where do palmar or plantar eminence fractures typically occur?
In the hindlimbs because distraction fractures of the plantar eminences occur due to avulsion of bony insertion of SDFT
What diagnostic tool is often used to better define fracture planes in comminuted fractures?
Computed tomography (CT)
How are middle phalangeal fractures classified?
Simple or comminuted
Classification of middle phalangeal fractures in simple or comminuted and they can be 4 types
1) dorsal or palmar/plantar osteochondral chip fractures
2) palmar or plantar eminence fractures (uniaxial or biaxial)
3) axial fractures from PIJ to DIJ
4) comminuted fractures
Which type of middle phalanx fracture is intraarticular?
Osteochondral chip fractures
Uniaxial and biaxial fractures disrupt the palmar aspect?
Uniaxial does not, but biaxial does disrupt the palmar aspect because as you see the image there is supsensory and SDFT attachement . Different immobilization for each and different tx can be considered
diagnosis
Figure 92-1. Dorsopalmar and lateromedial radiographs of an axial bony fragment in the palmar pouch of the PIP joint (arrows). Some are identified as incidental on prepurchase radiographs, but grow in dimension and later may result in lameness. The fragment has a fracture bed on the proximal border of the middle phalanx and is arthroscopically accessible.
diagnosis
Figure 18.2 (a) Lateromedial radiograph revealing an axially located fragment from the dorsoproximal articular surface of the
middle phalanx. (b) Arthroscopic view of the fragment protruding from the proximal articular margin of the middle phalanx (P2)
between the medial (M) and lateral (L) condyles of the proximal phalanx.
Figure 18.3 Fragmentation of the proximal dorsal and palmar articular margins of the middle phalanx. (a) Lateromedial radiograph.
(b) Palmar arthroscopic image demonstrating associated disruption of the scutum (arrows): P1: palmar condyles of the proximal
phalanx.
Figure 18.4 Palmarolateral–dorsomedial oblique radiograph
demonstrating a complete spiraling, biarticular, axial fracture
of the middle phalanx.
what happened?
Figure 18.6 (a) Dorsoplantar, (b) lateromedial, (c) DLPMO and (d) DMPLO radiographs of a complex fracture of a hindlimb middle
phalanx. This includes a biaxial plantar eminence fracture with additional fractures dorsally and extending into the DIJ.
Figure 18.9 Repair of a uniaxial fracture of a medial plantar eminence and concurrent PIJ arthrodesis. (a) Pre-operative
DMPLO
radiograph. (b) Intra-operative
photograph with reduction maintained by pointed forceps during dorsal to plantar lag screw fixation of
the fracture. (c) Intra-operative
fluoroscopic image following lag screw fixation of the eminence fracture.
treatment?
Repair of a uniaxial fracture of a medial plantar eminence (d) Intra-operative
photograph following lag screw fixation showing reduction of the eminence fracture (arrows). Note osteostixis of the articular
surfaces. (e) Post-operative
DMPLO radiograph illustrating completed lag screw fixation and PIJ arthrodesis.
What is a common cause of distraction fractures of the plantar eminences?
Sudden stops and turns
What type of forces are involved in fractures of the middle phalanx in Warmbloods?
Axial compression and bending forces (eventing)
What percentage of middle phalanx fractures involve the hindlimb?
About 70%
What type of fractures are most common in the middle phalanx?
Comminuted fractures
How soon the horse is back limb supporting after fractures like palmar/plantar process or axial fractures improve?
Within 24 hours
Which ligament contributes to the stabilization of the middle phalanx?
Strong collateral ligaments of PIP and DIP
Suspensory ligament of the distal sesamoid bone
What is the role of the palmar/plantar scutum in the middle phalanx?
Stabilizes the palmaro-/plantaroproximal aspect
How common are dorsal or palmar/plantar osteochondral fractures?
Rare
On which aspect of the middle phalanx do most osteochondral fractures occur?
Palmar or plantar
In which horse breeds are palmar/plantar fractures more prevalent?
Quarter Horses and Thoroughbreds
What is a characteristic feature of palmar/plantar osteochondral fractures?
They do not distract
What increases the likelihood of lameness in palmar/plantar osteochondral fractures?
Growth in situ of the fragments
What is the recommended treatment for lameness due to midphalangeal osteochondral fragments?
Surgical removal
In which case of uniaxial or biaxial fracture do you decide if is one plate or 2 plates dorsally
The decision to perform a PIJ arthrodesis using a single dorsal plate positioned axially in conjunction with abaxial transarticular
lag screws or using two dorsal plates positioned abaxially is determined by the pa/pl stability of the joint - disruption pal/pl two plates id mandatory
Where is the arthroscopic portal typically made for palmar/plantar fragment removal?
Voluminous palmar pouch of the PIP joint
Surgical removal of palmar or plantar fragments using arhtro is recommended with portal made proximal to the voluminous palmar pouch of PIP
What surgical approach is recommended for removing palmar or plantar fragments?
A) Arthroscopy
B) Open surgery through the DFTS
Where are located the dorsal osteochondral fragments?
dorsal rim of middle phalanx acess through arthroscopy by dorsal joint pouch
describe the entry of the arthroscope in the dorsal approach
Arthroscope entry is usually abaxial to the extensor tendon. Instrument access is adjacent to the fragment, and careful dissection is required in the tight dorsal recess of the PIP joint (
prongosis for removal of osteochondral fragments dorsal or palmar
favorable
Diagnosis
A) Oblique radiographic projection of a unilateral palmar eminence fracture of the middle phalanx. The limb is supported in a fiberglass cast for the transport to the clinic.
what happened?
Figure 18.5 Lateromedial radiograph demonstrating a biaxial,
plantar eminence fracture with displacement of the proximal
phalanx into the fracture plane and unstable subluxation of
the PIJ
Treatment?
(B) Postoperative oblique radiographic projection following insertion of a 4.5-mm cortex screw across the fracture, providing interfragmentary compression. The limb is supported in a fiberglass cast.
Figure 92-4. Palmar luxation associated with disruption of the palmar insertion of the middle scutum and SDF tendon. (A) Preoperative lateral radiograph. (B) Postoperative lateromedial projection showing reduction and application of two narrow 4.5-mm DCPs with four screws in the middle phalanx.
(C) Dorsoplantar projection showing plate position and distal screws angled to engage the middle phalanx. VetBooks
Figure 92-6. Biaxial fracture of the right hind middle phalanx. (A) Preoperative lateral radiograph shows plantar eminence distraction and pastern subluxation. (B) Dorsoplantar projection shows multiple fragments in the middle phalanx eminence fracture.
C and D) Postoperative radiographs showing application of two DCPs and independent lag screws to secure the plantar eminences to the middle phalanx.
Figure 92-7. (A) Dorsopalmar projection of a rarely occurring axial middle phalanx fracture. (B) Dorsopalmar postoperative radiographic projection after implantation of two 5.5-mm cortex screws using lag technique.
(A) Dorsopalmar projection of a rarely occurring axial middle phalanx fracture.
How do you approach the incision to place the plates in middle phalanx?
A. Inverted T
B. Inverted V
C. I shaped skin followed by Y tendon
D. V shape
AUER (Nixon) but other 2 fracture books (Watkins) advises inverted T
C. I shaped skin followed by Y tendon
is used to expose the proximal and middle phalanx
The collateral ligaments are severed to expose better the palmar/plant portions of the fx
Figure 92-8. Comminuted middle phalanx fracture of the right forelimb. (A and B) Preoperative radiographs show multiple fracture planes in the sagittal and frontal orientation. (C) Computed tomography shows additional fracture fragments and a more complex configuration for repair.
Figure 92-8. Comminuted middle phalanx fracture of the right forelimb. (A and B) Preoperative radiographs show multiple fracture planes in the sagittal and frontal orientation. (C) Computed tomography shows additional fracture fragments and a more complex configuration for repair.(D and E) Repair using two DCPs and multiple additional lag screws to capture palmar eminence fragments and sagittal fracture planes of the distal portion of the middle phalanx.
what is wrong?
Figure 18.8 Dorsoplantar radiograph of a failed attempt at lag
screw fixation of a uniaxial plantar eminence fracture. Note loss
of reduction and secondary fracture of the fragment that
followed repair.
Figure 18.9 Three‐hole 4.5 mm locking compression plate
designed specifically for proximal interphalangeal arthrodesis.
The distal stacked combi hole provides minimal intrusion to soft
tissues over the middle phalanx and distal interphalangeal joint.
Figure 82-9. Graphic illustration of an arthrodesis of the PIP joint, using a three-hole narrow** dynamic compression plate** and one 5.5-mm cortex screw applied in lag fashion across the joint on either side of the plate. The plate is applied axially over the dorsal aspect of the joint with the most distal screw inserted into the proximal aspect of the middle phalanx
