Carpus 95 - Carpus ACB fx and other pathologies Flashcards

Question

Conservative tx has been associated with good outcome but why Furst 2022 describes that has unfavourable healing?

Answer 1

- ACB has no periosteum or bone marrow and has a poor blood supply. Conservative management - fails to provide compression of the fracture ends in conservative management, which is exacerbated by the constant pull of the various tendons and ligaments on the bone, creating an unfavourable environment for healing.

Answer 2

Fig 3: Illustration of the lateral aspect of the accessory carpal bone with the two tendons of the ulnaris lateralis muscle. Ca, accessory carpal bone; S, insertion of one of the tendon of the **ulnaris lateralis muscle**; L, second tendon of the ulnaris lateralis muscle. Note the 2 branches of the ulnaris lateralis muscle and the presence of the groove where the fracture occurs

Answer 3

The typical hyperextension observed in race horses or eventing with opposing forces of the tendons leads to the fracture. ACB compression between the third metacarpal bone and the radius when the horse falls with the carpus in flexion

Answer 4

Number 7 - ulnaris lateralis muscle Number 8 - flexor carpi ulnaris muscle

Answer 5

Fig 2: Photographs of the preoperatively placed fibreglass cast utilised to facilitate the computer-assisted surgical repair of the accessory carpal bone (ACB) fracture. (a) The cast was placed prior to induction and with the horse standing to ensure immobilisation of the carpus in a fully extended position. Note: a piece of hardwood has been incorporated to allow the placement of the patient tracker. (b) Fenestration of the cast over the palmar aspect of the carpus to allow for surgical access to the ACB. (c) Intraoperative photograph showing the patient tracker anchored to the cast with two 3.2mm pins. The operating surgeon utilises the navigated pointer to determine the appropriate site for placing the skin incisions. The patient tracker and the pointer are both equipped with lightreflecting spheres, which are detected by an infrared optical digitiser and camera array (not shown).

Answer 6

Fig 1: Lateromedial radiograph (a) of the right carpus showing a zigzag shaped, complete and mildly comminuted fracture (arrowheads) in the dorsal third of the accessory carpal bone (ACB), with minimal palmar displacement. An additional thin radiolucent line (arrow), originating from the main fracture, is present in the proximal fourth of the dorsal fragment, suspected to represent an incomplete fracture. Given the lack of displacement and the interdigitation of the fragments, the surgeons hoped to stabilise these fragments in situ with the planned lag screw repair. With the aid of the navigated pointer For each cortex screw, a 1.5 cm longitudinal incision was made through the skin reaching the palmar surface of the ACB, followed by drilling a 2.5mm pilot hole. they were enlarged for the placement of a 4.5mm cortex screw (48mm in length) proximally and a 3.5mm cortex screw (50mm in length) distally. The proximal pilot hole was over-drilled with a navigated 4.5mm drill bit to create the glide hole and then a navigated 3.2mm drill bit to create the thread hole of appropriate width and depth After countersinking, screw length measurement and tapping, the two cortex screws were placed in lag fashion and tightened with the maximal strength achieved by holding the screwdriver with thumb, index and middle finger

Answer 7

6 weeks after srugery the surgical incisions were healed without complications and the horse was sound at walk. Since the fragment was deemed to be mainly extra-articular and difficult to reach by arthroscopy, its removal was performed through a navigated cut-down procedure guided by the navigated pointer

Answer 8

Because osteoarthritis of the antebrachiocarpal joint can happen due to continued synovial irritation because of the unstable articular fragment.

Answer 9

The 6-hole APTUS® 3.5 Talonavicular Fusion Plate with TriLock© self-tapping screws can be re-locked in the same plate hole at different angles up to three times, without loss of stability of the locking mechanism

Answer 10

pure titanium (ASTM F67, ISO 5832-2)

Answer 11

TriLock© screws from titanium alloys (ASTM F136, ISO 5832-3)

Answer 12

Titanium implants have unique biocompatibility properties that encourage soft tissue and bone adhesion to the implant surface and are beneficial in terms of reducing surgical site infection

Answer 13

closed, mildly displaced, mainly vertical comminuted fracture of the ACB with involvement of the antebrachiocarpal joint was diagnosed Lateromedial (a) and dorsopalmar (b) radiograph

Answer 14

local subcutaneous infiltration at the proposed incision was performed using 15 ml of mepivacaine. The optimal skin incision in a proximal to distal direction was determined with needles and radiographs. During the procedure, the primary surgeon and the assistant sat on height adjustable rolling stools. The primary surgeon was positioned directly in front of the operating field while the assistant sat to the right. A second assistant stood aside to hand out instruments during the entire surgery. A 10 cm vertical skin incision centred over the dorsolateral aspect of the ACB was made with a No. 10 scalpel. The antebrachial fascia was sharply dissected to expose the ACB. A 6-hole, left, APTUS® 3.5 Talonavicular Fusion Plate (A-4960.11) (Figure 2a) was contoured to the lateral surface of the ACB using two plate bending pliers. These pliers were placed exactly over the screw holes of the plate with the labelled side facing upwards to avoid damaging the screw holes. The plate should not be contoured to an angle >30°. Then the plate was temporarily fixed to the ACB with an olive pin (Figures 2b and 3). The correct position of the plate was confirmed by radiographs obtained in two planes (lateromedial and dorsopalmar projections). Five screw holes were drilled sequentially with a 3-mm drill bit and 3.5-mm self-tapping APTUS TriLock© screws (Medartis AG) (1 × 18 mm, 2 × 20 mm and 2 × 22 mm) (Figure 4) were firmly anchored in the bone (Figure 5). The appropriate screw length for each screw was determined with help of a depth gauge. At the end of the procedure (120 min surgical duration) radiographs were obtained to verify the correct placement and length of the screws at the end of the fixation. The dorsoproximal screw hole was left empty, due to the risk of engaging the fracture line. The small dorsoproximal fracture fragment was left in place.

Answer 15

APTUS® 3.5 talonavicular fusion plate (a) and the olive pin (b). Note the prefabricated hole in the plate for the application of the olive pin (*).

Answer 16

3.5-mm APTUS TriLock© screw

Answer 17

In contrast to the LCP technology, the TriLock© system has the advantage that screws can be angled up to 15° in the plate in all directions to achieve an optimal screw position. Also the curvature of the bone and its thin nature, it is very difficult to place two or more cortex screws

Answer 18

a push–pull device for the LCPs to fix the plate to the bone. In contrast to the push–pull device, the olive pin is smaller and is not attached in a screw hole, but in a hole prefabricated for this purpose in the plate centre (Figures 2c and 3).

Answer 19

all the complications or risks that are present during the recovery phase after general anaesthesia can be eliminated by performing the surgery standing and it also reduces the clients' costs

Answer 20

The small dorsoproximal avulsion fragment was not removed intraoperatively in a standing scenario for several reasons: The fragment was firmly attached to the accessorioulnar-, accessoriocarpoulnar ligaments and the surrounding fascia. As described in the literature and in the author's experience in some cases it is difficult or even impossible to remove avulsion fragments, because they can be buried within the soft tissue structures and under the synovial membrane (McIwraith 2020). disadvantage. The authors opted to leave the dorsoproximal fragment in place, which despite mild antebrachiocarpal osteoarthritis, did not negatively impact the outcome of the case. Aßmann et al 2023

Answer 21

Subcutaneous swelling over the dorsum of the carpus

Answer 22

History of trauma to the region

Answer 23

Surgical extirpation with S shape incision and dissect fluid filled sac and surrounding tissues and place penrose and suture. Cast and stall rest 8 weeks

Answer 24

Flexed lateral radiographic view of the carpus of a 7-year-old Thoroughbred with an exostosis of the caudal aspect of the distal radial physis (arrows). When these lesions extend more than 1 cm into the canal, they frequently are a cause of lameness.

Answer 25

Location and histologic examination

Answer 26

caudal aspect of the **distal radial physis**

Answer 27

audal aspect of the **distal metaphysis of radius** Osteochondromas are present on the caudal aspect of the distal radius metaphysis normally 2–4 cm proximal to the distal radial physis.

Answer 28

thought to result from separation of a portionof the metaphyseal growth plate margin creating an islandof chondrogenic tissue, capable of endochondral ossification,that is carried into the metaphysis with growth of the bone

Answer 29

Caudal radial physeal exostoses. A, A lateromedial radiograph of the distal radius of a horse with persistentcarpal sheath effusion and lameness. The exostoses appear as sharp bony (arrow) spikes that protrude a variabledistance toward the carpal sheath.

Answer 30

A radial osteochondroma. A, Lateromedial radiographdemonstrating a sharply pointed osteochondroma on the distalcaudal metaphysis of the radius.

Answer 31

Effusion of the carpal canal

Answer 32

Intrasynovial anesthesia of the carpal canal

Answer 33

Intrasynovial injection of hyaluronan and corticosteroids

Answer 34

Short-term response to intrasynovial injection

Answer 35

Carpal canal endoscopy

Answer 36

5-mm osteotome

Answer 37

Soft tissue structures and adhesion formation

Answer 38

Box stall confinement for 4 weeks and pasture turnout for 4 to 8 weeks

Answer 39

Valgus deformity

Answer 40

A) Physeal dysplasia B) Joint laxity C) Cuboidal bone hypoplasia

Answer 41

A) Splints B) Periosteal elevation C) Transphyseal bridging

Answer 42

Traumatic events

Answer 43

1) With an obvious deformity in the carpus 2) Bearing weight but showing marked lameness

Answer 44

Cast application for 3 months

Answer 45

Decreased carpal flexion

Answer 46

When the bone column collapses under weight - Pancarpal arthrodesis

Answer 47

Plate fixation

Answer 48

Loss of skin over the carpus

Answer 49

A fall and teh tendons are the extensor carpi radialis and the co,,on digital extensor tendons

Answer 50

Radiography reveals a mineralized density within the synovial structures. Ultrasonography is helpful in determining whether or not the mass is within or adjacent to the synovial structure

Answer 51

B) Effusion of the carpal structure positive to IQ block

Answer 52

Arthroscopic or tenoscopic removal

Answer 53

Wound management

Answer 54

Increased postinjury stumbling

Answer 55

Figure 95-24. Treatment of a coronation injury. (A) Appearance of the injury. (B) A 1- to 2-mm rim is sharply removed around the skin defect. (C) Careful débridement of the subcutaneous tissues aids in determining if the joint is involved as well. (D) Needles placed from the palmar aspect of the carpus into the joints for joint lavage allow verification of any potential joint involvement. (E) Alternatively, the needles may also be inserted from the dorsolateral or dorsomedial aspect of the carpus. (F) After placing one or two drains, the skin is closed in routine fashion.

Answer 56

Figure 95-25. Synovial osteochondromatosis. Flexed lateral (A) and dorsomedial-palmarolateral 45-degree (B) radiograph of a mineralized mass within the radial carpal joint in a 2-year-old Standardbred filly. Arthroscopic (C) view of the mass within the radial carpal joint.