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75 Cards in this Set
- Front
- Back
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Keys For successful arthrodesis:
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as much cartilage should be removed as possible because persistence of cartilage minimizes bone contact, prevents vascular invasion, and decreases ossification
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What affect does improving the stability of the arthrodesis have?
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improves post-operative comfort and minimizes patient morbidity
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Arthrodesis of the DIP indications:
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severe DIP arthritis, collateral ligament rupture that results in joint instability, rupture of the DDFT at the level of the navicular bone, chronic intra-articular fractures or septic arthritis
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Surgical approaches for DIP arthrodesis:
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dorsal approach, palmar-plantar approach
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Which surgical approach to DIP arthrodesis is preferred?
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Dorsal, because there is less soft tissue disruption and there is better purchase of the screws
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Disadvantage of the dorsal approach to DIP arthrodesis:
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penetrates the hoof capsule leading to increased risk of infection
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What pre-operative preparations are performed For the dorsal approach to DIP arthrodesis?
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foot is prepared the day before surgery by removing the superficial horn layer and scrubbing or soaking the foot in antiseptic solution before application of a sterile bandage
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Describe dorsal DIP arthrodesis:
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joint is approached arthroscopically first, both dorsal and palmar-plantar, and as much articular cartilage as possible is debrided through the arthroscopic approaches, 10mm drill bit is used to create 3 parallel holes in the dorsal aspect of the hoof wall. Once P3 is exposed, a glide hole is drilled with a 5.5 drill bit through P3 in a dorsodistal to palmaro- plantaroproximal direction. The glide holes are centered 1/3 the distance between the extensor process and the tip of P3. The thread holes are created with a 4.0 drill bit to enter the center of the articular surface of distal P2. 5.5 screws are placed and hand tightened. Hoof wall defects are filled with antibiotic impregnanted PMMA and sealed with cyanoacrylate
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How much cartilage can be removed with the dorsal DIP arthrodesis:
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up to 80% of the cartilage
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Post-op care for DIP arthrodesis:
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half limb cast is places and maintained for 2 months
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Describe palmar-plantar approach DIP arthrodesis:
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first incision is made dorsally 1 cm proximal and parallel to the coronary band, through the skin, tendon, and joint capsule and extending laterally and medially to transect the collateral ligaments. With the joint disarticulated, as much of the articular surface is debrided with curettes. A second incision is made on the palmar-plantar aspect of the limb, aligned longitudinally over the pastern joint. The DFTS is entered and the DDFT is transected. Stab incisions are made through the distal sesamoidan ligaments for access to the palmar-plantar aspect of the distal P2. 3 transarticular screws are placed in a proximopalmar (-plantar) to dorsodistal direction. The glide hole is made with the joint disarticulated to guide placement. The thread hole is created in P3 and 5.5 cortex screws are inserted and hand tightened. The dorsal incision is closed first, in 3 layers including the extensor tendon and joint capsule, the SQ and the skin. The DDFT should be apposed if possible before closing the final 2 layers of the palmar-plantar incision, a combined SQ and tendon sheath and then the skin
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How much cartilage can be removed with the palmar-plantar DIP arthrodesis?
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70%
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Post-op care for palmar-plantar DIP arthrodesis:
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half limb cast or transfixation cast are placed, with 1 change, for 3 months
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Indications for Pastern joint arthrodesis:
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severe OA, luxation or subluxation, or during repair of a P2 or P1 fracture
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Approaches to PIP arthrodesis for non-fracture diagnoses:
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lag technique or by a combination of a plate and the lag technique
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When is PIP Lag technique used?
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for young foals or can be considered in older horses with severe OA, using a minimally invasive approach
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Disadvantages of PIP lag technique?
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need for supplemental cast coaptation because the arrangement of the screws provides no stability, especially dorsally
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Long term success of PIP lag technique:
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fore limb 50-85 hind limb 80-89%
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What does instability of PIP lag technique result in?
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Instability is painful and leads to excessive bone formation which can impinge on the DIP joint
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Success rate of PIP Combination of transarticular lag screws and a plate:
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81% for fore limb and 95% for hind limbs
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advantage of the screw and plate PIP arthrodesis:
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compresses the entire surface of the joint, because tensile forces on the palmar-plantar aspect of the joint are neutralized by the screws and the plate provides stability to the dorsal aspect of the joint
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describe plate PIP arthrodesis:
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inverted midline T incision is made from the fetlock joint to 2 cm dorsal to the coronary band and extended 4 cm medial and lateral. The common digital extensor tendon is transected in a V shaped incision. The skin, SQ and tendon are retracted. The joint capsule and collateral ligaments are transected to disarticulate the joint. Cartilage is removed from the joint surfaces and distal P1 is rasped to improve contact between P1 and P2. Osteostixis is performed at 5mm intervals using a 2.5 drill bit. Using a LCP, the stacked combi-hole is placed distally and a 5.5 locking head screw is inserted but not completely tightened. 5.5 guide holes are made from the distal aspect of P2 to enter the middle of the joint surface. A countersink is used to prepare the cortex of P2. The joint is closed and a 4.0 perpendicular thread hole is place through the proximal or middle DCU in load position. A 5.5 screw is inserted but not fully tightened. The thread holes for the transarticular screws are prepared and 5.5 cortical screws are placed and all 4 placed screws are tightened to compress the joint surface. The final 5.0 locking head screw is placed in remaining hole of the plate. The CDE is apposed with PDS and skin is closed with staples and prolene.
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Post-op care for plate PIP arthrodesis:
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distal limb cast is applied for recovery and maintained for 2 weeks. Half of the staples and skin sutures are removed at 2 weeks with removal of the cast, and the remaining skin closure is removed at the following bandage change. bandaged for another 3 weeks. stall rested for 6 weeks and then a gradual hand walking exercise program can be instituted for 6 weeks. allowed paddock rest for an additional 3 months
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Approach to PIP arthrodesis for P2 or P1 fractures:
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Instead of 2 transarticular screws and an axial plate, the fracture is reduced with 3.5 cortical screws in lag fashion and application of either 2- 7 hole 3.5 broad DCP or a 5 hole 4.5 narrow DCP plate on the dorsomedial and dorsolateral aspect of the joint
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Why are 3.5 cortex screws used with P2, P1 fixation and PIP arthrodesis?
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screw head can be buried in the bone, minimizing interference with the plates
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Disadvantages of minimally invasive approach to plate PIP arthrodesis:
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more technically challenging, required intra-operative imaging for implant placement, fusion is slower, and more cast support is required
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Describe minimally invasive PIP arthrodesis:
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articular cartilage is removed through by drilling with small incisions made laterally and dorsally. Stab incisions are used for placement of the LCP, placement of the trasacrticular screws, and placement of the distal LCP locking head screw
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Complications of PIP arthrodesis:
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cast sores, incisional infection, implant infection, and construct failure in the early post-operative period and persistent lameness, cast morbidity, excessive bone formation, and arthritis of the DIP in the long term
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Indications for fetlock arthrodesis:
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suspensory apparatus failure, comminuted P1 fractures, severe OA, and with or without ostectomy for the management of severe flexural deformities
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What occur with suspensory apparatus failure?
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hyperextension of the fetlock because of either fracture of both proximal sesamoid bones, rupture of the distal sesamoidean ligament, or rupture of both suspensory branches
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What is the most common failure with suspensory apparatus failure?
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Fracture of the proximal sesamoid bones
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Describe fetlock arthrodesis:
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skin incision is made on the dorsolateral aspect of the MC from proximal MC to the level of the PIP joint, over and through the lateral digital extension tendon. The joint capsule is incised parallel to the surface of the joint and incision is continued laterally to cut the lateral collateral ligament and the lateral metacarposesamoidean ligament. The joint is disarticulated and the articular cartilage is removed from all surfaces, followed by contouring of the distal end of MC/MT3 to allow better contact with proximal P1. Osteostixis is performed. A 10-14 hole LCP (or 4.5B or 5.5B LCDCP or DCP) is applied dorsally after a 10 degree bend is placed between the 4th and 5th hole from the distal end of the plate, and centering the bend over the fetlock joint. A cortex screw is applied to the 2nd hole from the distal end of the plate, and the 1st and 3rd holes are filled with locking head screws to apply the plate to P1. A tension band is placed on the palmar-plantar aspect of the joint. an angled tension device is placed through the most proximal hole and attached to MC/MT3 with a unicortical cortex screw. Using a socket wrench, the angled tension device pulls the plate proximally, which tightens the tension band on the palmar-plantar surface. The second hole from the top and the 6th hole are filled with cortex screws. 2 locking head screws are placed in MC/MT3 before the angled tension device is removed. The 2 plate holes on either side of the joint are filled with cortex screws that cross the articular surface in lag technique. Additional transarticular screws can be placed on either side of the plate to increase stability
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Why is a tension band required for fetlock arthrodesis:
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dorsally applied plate will fail due to cyclic failure
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How is a tension band created for fetlock arthrodesis?
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placing a 5.5 cortex screw in lag from distal MC/MT3 through each sesamoid bone or using 1.25mm cerclage wire or 1mm diameter cable in a figure 8
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When are the sesamoid bones lagged to MC/MT3 for tension band placement?
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if the sesamoid bones are not fractured or the suspensory branches are not ruptured
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When is figure 8 wire or cable used for tension band?
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If the suspensory branches are not ruptures and the sesamoid bones are not fractured (i.e. the distal sesamoidean ligament is rupture)
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How is cerclage wire/ cable figure 8 tension band created?
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3.2mm drill is used to make dorsal to palmar-plantar holes through the distal aspect of MC/MT3 and the proximal aspect of P1, approximately 4-6cm from the joint surface. Wire is placed dorsal to palmar-plantar with 1 wire tightened laterally and 1 wire tightened medially
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What position is the fetlock in during placement of tension band?
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neutral or slightly flexed (5 degrees)
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Complications of fetlock arthrodesis:
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infection, instability of the construct, contra-lateral limb laminitis, and PIP joint luxation
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Survival for fetlock arthrodesis using an open technique and a DCP?
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25%
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Survival for fetlock arthrodesis using a minimally invasive technique and a DCP?
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33%
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Survival for fetlock arthrodesis using a open approach and a LCP?
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67-75%
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Survival for fetlock arthrodesis Using an minimally invasive technique and a LCP?
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75%
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What improves success of fetlock arthrodesis?
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arthrodesis is the primary treatment and better for non-traumatic diseases such as OA
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Examples of Carpal arthrodesis:
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fusion of the CMC joint due to severe CMC OA, partial arthrodesis, and pancarpal arthrodesis
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How is CMC OA treated?
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drilling technique
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Success rate of CMC drilling?
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86% of horses were considered sound, with 67% returned to previous activity
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How much cartilage is removed with CMC, drilling techniques?
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16-33% of cartilage with a 4.5 drill and 14-23% with a 5.5 drill
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Examples of Partial arthrodesis:
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fixing either the proximal row of carpal bone to the distal row and MC3, fixing the distal row of carpal bones to MC3, or fixing the proximal row to the distal radius
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Describe partial carpal arthrodesis:
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2 6-8 hole DCP or LCP plates are applied dorsolateral and dorsomedial through 2 vertical skin incisions on either side of the extensor carpi radialis. Articular cartilage should be removed, interfragmentary compression obtained with lag screws in cases of fracture, and osteostixis performed prior to fixing the plates with screws
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Intra-operative complications of partial and pancarpal arthrodesis:
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lack of skin to cover the 2 dorsally applied plates
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Methods to mobilize skin for closure over partial or pancarpal arthrodesis:
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Placement of tension sutures in the skin the day prior to surgical fixation, towel clamps prior to closure, relief incisions distant from the surgical site may facilitate closure
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Indications for Pancarpal arthrodesis:
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comminuted fractures of both proximal and distal carpal rows and for severe OA
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Describe pancarpal arthrodesis:
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5.5 LCP or DHS/DCS plates are used, with 2 plates applied, dorsomedial and dorsolateral, through 1 skin incision
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Complications of carpal arthrodesis:
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support limb laminitis, incisional infection, and implant infections
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Indication for Scapulohumeral arthrodeses:
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mini horses or small horses, treatment of shoulder luxation or OA
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Options for scapulohumeral arthrodesis:
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Either a 10-11 hole 4.5N DCP/LCP using 4.5 cortex screws is applied to the cranial surface of the scapula and humerus after osetctomy of the intermediate tubercle or a 16 hole broad LCP or reinforced 3.5 DCP is applied to the cranial aspect of the scapula and humerus after transection of the biceps tendon at the level of the joint
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What advantages for the 3.5B have over the 4.5N in scapulohumeral arthrodesis?
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has the same cross-sectional, but 3.5B has more screw holes and the screw holes are smaller so there is more metal surrounding the holes
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How can Distal hock arthrodesis be performed?
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chemical induced ankylosis, laser facilitated ankylosis, transarticular drilling, and plate fixation techniques
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Material for Chemical ankylosis:
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monoiodoacetate or ethyl alcohol
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Disadvantages of MIA:
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severe discomfort, soft tissue swelling and necrosis, and progression of OA to the PIT joint, Convalescence time is variable as is outcome of ankylosis
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Describe MIA use:
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100-250mg is injected IA to cause cartilage death
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MOA of ethyl alcohol:
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cartilage necrosis by nonselective protein denaturation, cell propoplasm precipitate and dehydration
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Benefits of Ethyl alcohol:
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neurolytic agent blocking sensory innervation to the articular cartilage
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When was ethyl alcohol ankylosis evident radiographically?
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4-6 months
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Laser for laser facilitated ankylosis:
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Nd:YAG or diode laser
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MOA of laser ankylosis:
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destroy the cartilage with heat and vaporization of the synovial fluid
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Describe Transarticular distal tarsal drilling:
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3 cm vertical skin incision dorsomedial aspect of the limb centered over the DIT and TMT. A single drill site entry is created for each joint midway between a line extending from the MT2/MT3 groove and the dorsal aspect of the tarsus at the level of the DIT and TMT. A 4.5 drill bit creates 3 fan like patterns in each joint. The tracts are drilled in pairs starting with a 20mm tract directed from dorsomedial to the most lateral palpable extremity of MT4. The second tract is a 20mm tract directed from dorsomedial to plantar 30 degrees from the first drill tract. The final tract is 35mm angled dorsally 30 degrees from the first tract.
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Cartilage removal with tarsal drilling?
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18% of the cartilage is removed from the proximal MT3 and 22% from the proximal T3
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Disadvantages of tarsal drilling:
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intra-opertaive hemorrhage from trauma to the perforating branch of the cranial tibial artery, penetration of the tarsal canal resulting in excessive periosteal reaction, and excessive side to side drilling resulting in instability, pain, and excessive periosteal reaction
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Tarsal drilling success rate:
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47-85%
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Options for plate distal tarsal arthrodesis:
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narrow DCP or LCP applied over the dorsomedial aspect of the joints after removal of fibrous and exostosis from the region, application of a 5 hole 4.5 N DCP dorsomedially after drilling the articular surfaces with a 4.0 drill bit and filling the drill tracts with cancellous bone graft, specifically designed LCP tarsal arthrodesis plate which is applied dorsomedially, implantation of stainless steel cylindars that contain cancellous bone graft
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describe placement of 5 hole 4.5N DCP for distal tarsal arthrodesis:
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proximal plate hole is filled with a 5.5 cortex screw into the central tarsal bone. A tension device is applied to proximal MT3 and tightened and 2 additional screws are placed in MT3. The tension device is removed and the remaining screw holes are filled, preferentially into the central tarsal bone and third tarsal bone. Transarticular screws through the plate and adjacent to the plate counteracts rotational instability inherent in applying just the plate
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Treatment of DIT or TMT luxation:
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application of a 12-14 hole broad DCP or 5.5 LCP to the plantarolateral aspect of the hock from the calcaneous to the proximal MT3, with or without removal of MT4
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Options For talocalcaneal arthrodesis:
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3 transarticular screws are placed in lag fashion with or without a plate contoured to the calcaneal surface or 3 screws can be placed from the dorsomedial aspect of the talsus, across the medial facet, into the calcaneous
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