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88 Cards in this Set
- Front
- Back
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Sacroiliac luxation |
Disruption of the articulation between the wing of the sacrum and the iliac wing
Sacral fracture may accompany sacroiliac luxation |
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Displacement of the pelvic girdle |
Requires bilateral separation of the sacroiliac joints, fracture of the pelvic bones at 3 sites, or a combo of these injuries |
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What nerves may be affected by damage to the sacroiliac joint? |
- Femoral nerve
- Sciatic nerve
- Neurological deficits are common when sacral fractures transverse the spinal canal or the sacral foramina |
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Physical exam findings for pelvic fractures/displacements |
- When the patient is sedated, dorsoventral movement of the ilium may be detected |
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What are you trying to determine with pelvic radiographs after trauma? |
- Ventrodorsal and lateral radiographs to assess degree of injury to the hemipelvis and to delineate fracture line - Sacroiliac luxation (visible step at the sacroiliac joint on V/D view) - Width of the pelvic canal (<50% normal will require surgery) |
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Types of pelvic fractures |
- Ilium (body or wing) - Acetabulum - Sacral - Ischium (body and floor) - Pubis |
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Conservative medical management for sacroiliac luxation |
- Enforced rest for 3 weeks - Supervised activity after 3 weeks for 3 weeks, with exercise amount gradually increasing - NSAIDs - Well padded bedding, changed often, checking animal for decubital ulcersand urine scalding - Stool softeners - Physio of joint |
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When is surgery suggested for pelvic fractures? |
- If there is narrowing of the pelvic canal (<50% normal) because it can cause constipation/obstipation
- Always check patients urinary function before surgery because the nerve may be damaged |
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Surgical anatomy of the sacroiliac joint |
- Two main components: Semilunar, crescent shaped synovial joint & a fibrocartilaginous synchondrosis
- Dorsal and ventral ligaments |
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Complications with pelvic fractures |
Pelvic canal narrowing, which can lead to pelvic canal stenosis, causing:
- Obstipation
- Dystocia |
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How does the shape of the pelvis affect how it is fractured? |
Box-like shape so usually the ischium, ilium and pubis are fractures simultaneously, resulting in loss of weight transfer from the affected limb to the spine. |
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Iliac fractures |
- Usually long oblique fractures of the body
- The caudal fragment displaces medially and cranially, compromising the pelvic canal |
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What soft tissue structures can be injured with a pelvic fracture? |
- Bladder and urethral rupture (esp. if bladder is full during trauma) - Muscle separation or avulsion of the bony insertion of the rectus abdominis muscle - Herniation of abdominal viscera, possibly causing strangulation + necrosis of tissue - Impaired sensory and motor functions of the lumbosacral plexus or sciatic nerve |
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What is the most common reason for surgical intervention of a pubic/ischial fracture? |
Associated soft tissue herniation:
- Herniation of abdominal viscera can result from separation of the pubic symphysis or from cranial pubic ligament avulsion
- Herniation may occur caudal to the acetabulum, but rarely (perineal) |
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DDx of pelvic fractures |
- Fracture and/or separation of the sacroiliac joint
- Acetabular fracture
- Coxofemoral luxation |
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When can medical management be used for pelvic fractures? |
- Iliac fractures that are minimally displaced and relatively stable
- Owner unable to afford surgery
- Isolated ischial and pubic fractures |
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When should conservative treatment not be done for pelvic fractures? |
- If multiple fractures occur, reduction and stabilisation of the primary WB segment (ilium and acetabulum) should be done - If not, the pelvic girdle will be unstable and excessive WB w/o stabilisation may cause further medial displacement of the hemipelvis, resulting in continued pain, further compromise of the pelvic canal, and ilial malalignment w/ CoxF joint |
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When should surgery be performed on pelvic fractures? |
- Bilateral pelvic limb injury (enables walking sooner and have less intensive post-op care) - Notably displaced ischial fractures - Fractures associated with ST herniation - Reestablishment of integrity in the pelvic girdle of intact female D/C that will be bred
- Surgery can often shorten rehabilitation time |
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Why are bone plates and screws the best implant to use for ilial fractures? |
- Bone plates are the only implants that can be curved to mimic the shape of the lateral ilium.
- Once applied they will maintain reduction of the ilium in that shape.
- Prevents collapse of pelvic canal. |
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What are the key things for owners to watch for before and after pelvic surgery? |
- Urination and bowel movements
- Soft tissue herniation |
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Ilium anatomy |
- Iliac wing (cranial) and iliac body (btwn wing and acetabulum) - Curves medially to allow for the middle and deep gluteal muscles (thin bone here) - Medial sacroiliac joint - Sciatic nerve is medial-dorsal to the body - Required for weight transfer from the limb to the axial skeleton |
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Ischium anatomy |
- Lesser ischiatic notch (cranial), ischial floor (medial), ischial tuberosity (caudal)
- Sciatic nerve runs over the ischial notch |
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Obturator foramen |
Located caudal to the cranial pubic brim
Obturator nerve (adducting limb) |
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How can pubic fractures be stabilised? |
With orthopaedic wire aligning the two hemipelvises |
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How are long oblique pelvic bone fractures treated? |
Lag screws |
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Complications of pelvic fractures |
Screw loosening, possibly resulting in loss of fracture alignement and compromise to the pelvic canal is most common |
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Acetabular fractures |
Occur through the articular surface and medial fossa of the acetabulum.
Usually occur with other pelvic fractures |
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Types of acetabular fracture |
- Cranial (WB: surgery)
- Central (WB: surgery)
- Caudal (conservative)
(area of articular surface affected) |
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DDx of acetabular fractures |
- Capital physeal fractures
- Coxofemoral luxations
- Proximal femoral fractures
- Ipsilateral iliac or ischial fractures |
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When can acetabular fractures be treated conservatively? |
- Very young animals with stable fractures not involving the WB zone of the acetabulum or with nondisplaced physeal fractures
- Using a non-WB sling (velpeau sling) |
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Surgical treatment of acetabular fractures |
- Anatomic reconstruction of the articular surface and rigid stabilisation needed to restore acetabular joint function and decrease DJD - Plates and screws normally - If irreperable, can do femoral head and neck ostectomy, with acetabular briding and stabilisation |
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Hip joint (Coxofemoral) structure |
- Femoral head and acetabulum (ball-and-socket) - Dorso-lateral acetabulum is articulating - Medial acetabulum originates the ligament of the femoral head - Fibrous joint capsule originates from the lateral acetabular rim, inserting on the femoral neck |
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Hip Joint stability |
- Normal conformation
- Surrounding musculature (gluteal mm., internal and external rotators, and iliopsoas m. medially)
- Suction-like effect of synovial fluid
- Ligament of the femoral head |
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Sciatic nerve location |
Courses dorsomedial over the ischial body to the dorsolateral caudal acetabulum |
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Surgical exposure of the hip joint |
- Osteotomy of the greater trochanter w/ attached gluteal muscles
- Incision into joint capsule |
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Complications of acetabular fractures |
- Reuslt in DJD (minimised with careful reduction and stabilisation) - Sciatic nerve injury - Delayed union and nonunion - OSteomyelitis Fixation failure - Poor decision making for implant type |
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Femoral diaphyseal fractures |
Result in disruption of the continuity of the diaphyseal cortical bone |
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Supracondylar fractures |
Fractures of the distal diaphysis |
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DDx of femoral fracture |
- Muscle contusion
- Coxofemoral luxation
- Fractures of the pelvic girdle
- Ligamentous injuries of the stifle |
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Why is conservative management not recommended for femoral fractures? |
Casts or splints do not provide adequate stabilisation of the femur and are awkward |
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Implant use for fractures of the femoral diaphysis with a FAS of 0-3 |
- Bone plate and IM pin
- Bone plate and screws
- Interlocking nail |
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Implant use for fractures of the femoral diaphysis with a FAS of 4-7 |
- ESF with IM pin tie in
- Bone plate and screws with or without IM pin
- Interlocking nail |
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Implant use for fractures of the femoral diaphysis with a FAS of 8-10 |
- IM pin with cerclage wire or ESF
- Flexible bone plate and screws |
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Isthmus |
The narrowest part of the femoral marrow cavity located in the proximal 1/3 of the bone, just distal to the third trochanter |
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Femur shape |
- Diameter thinner proximally than caudally
- Curved in a cranial to caudal direction (most accentuated in the distal 1/3)
- Cat femurs are straighter, with little curve |
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How is rotational alignment achieved in nonreducible comminuted femoral fractures? |
1. Aligning the roughened caudal surface of the femur of the attachment of the adductor magnus m.
OR
2. Achieving the normal spatial relationship (90 degrees) btwn the greater trochanter and patella |
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Muscles over the femoral diaphysis |
- Cranial: Fascia lata
- Lateral: Biceps femoris (superficial), vastus lateralis (deep over surface of femur) |
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What is the main concern with IM pin placement in the femur? |
- Isthmus determines diameter of IM pin - The more curvature and the more distal the fracture, the smaller the pin must be - Controlling the pin exit site at the trochanteric fossa because it may cause tissue irritation, sciatic nerve damage, and interfere with femoral head development in immature animals |
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Complications of femoral diaphyseal fractures |
- Delayed union. nonunion and malunion - Osteolmyelitis and pin tract infection - Fixation failure - Sciatic nerve injury (improper IM pin placement) - Poor implant choice and implant migration |
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Common failures in femoral diaphyseal fracture fixation |
- Failure to provide adequate rotational stability leading to delayed union and nonunion - Use of just IM pin stabilising femoral diaphyseal # results in # instability/implant migration - Attempting to reconstruct nonreducible fractures destroys the biological environment and delays healing, contributing to implant failure |
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Femoral neck fractures |
Occur at the base of the neck where it joins the metaphysis of the proximal femur |
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Why are femoral neck fractures mechanically unstable? |
- The length of the moment arm acting at the fracture is extensive (entire femoral neck)
- The plane of the fracture is along the lines of maximal shear stress so compression of the fracture surface is necessary to resist high shear stress |
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Articular femoral fractures |
Occur through the femoral head (proximal) or the femoral trochlea (caudal) |
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DDx for trochlear fractures |
- Deranged stifle
- Tumour |
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Surgical treatment of femoral head and neck fractures |
- Single fracture plane: Lag screw and K-wires
- Irreperable comminution: Total hip replacement or femoral head and neck ostectomy |
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Surgical repair of trochlear fractures |
- Lag screws
- Buttress plate for comminuted fractures |
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Angle of inclination |
- The femoral neck-femoral shaft junction in the frontal plane
- 135 degrees
- Take into account for surgical reconstruction |
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Tibial tuberosity osteotomy |
May be indicated for additional exposure of comminuted trochlear fractures |
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Intertrochanteric fractures |
- Involve the femoral neck, greater trochanter, and proximal femoral metaphysis
- If adult use plates and lag screw stabilisation of the femoral neck fixed to the proximal femur
- If immature, mulitple small pins can be used in the femoral neck and metaphysis |
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Complications of femoral neck fracture |
- Poor implant choice - Inappropriate reduction - Significant bending and shearing stress across the fracture plane place extreme bending load on implants - Use of K-wires or small pins when prolonged healing is expected - If fail to heal: femoral head and neck osteotomy |
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DDx for femoral physeal fractures: |
Proximal: Hip joint luxation, femoral neck fracture, acetabular fracture
Distal: Diaphyseal fractures and ligamentous injuries of the stifle |
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Proximal capital physis |
Btwn the femoral epiphysis and the femoral neck and acts as a barrier for passage of blood vessels from the femoral neck to the femoral epiphysis. |
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Distal femoral growth plate |
- W-shaped
- Lies at the joint capsule reflection of the stifle
- Its configuration and the cancellous bone surface provides a degree of inherent stability for fractures |
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Patellar fractures |
- Result from loss of bony and articular continuity between the superior and inferior poles of the patella. - Transverse #, fragmentation or comminution - Direct trauma (RTA) or Indirect trauma (forceful contraction of the quads, causing excessive tensile forces to be applied across the body of the patella) |
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Quadriceps muscles and fragmented patellar fractures |
- Fragmentation of the patella is a disabling injury because it causes loss of quad function and therefore inability to support weight. - W/o treatment that two fragments will separate due to the quads m. and patellar tendon pulling - A fibrous union develops btwn the fragments affording some stability, but not enough |
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DDx of patellar fractures |
- Lacerations or rupture of the patellar tendon, resulting quads insufficiency
- Made based on radiographs |
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When should conservative treatment be used for patellar fragments? |
- Cats with minimal displacement of the patellar segments
- Small fragments near the proximal or distal pole if they do not interfere with motion of the stifle joint
- Soft padded bandage and lateral splint |
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Function of the patella |
1. To maintain straight-line stability during contraction of the quads muscle group
2. To provide mechanical efficiency for the quads |
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Stabilisation of patellar fracture surgically |
Tension band wire for transverse fracture |
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Complications of patellar fractures |
- Felines treated with tension band wires very frequently result in additional fractures and fragment displacement
- Transvere proximal tibial fractures in cats with chronic nonunion of transverse patellar fractures |
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Types of tibial fractures |
- Avulsion - Transverse - Oblique - Spiral - Comminuted/severely comminuted - Pathological fracture - Open fractures since ST coverage is minimal |
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DDx of tibial fractures |
Traumatic or pathologic |
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Medical management of tibial/fibular fractures |
- Splints and casts for closed, nondisplaced, or greenstick fractures in immature animals. Stifle and hock can be immobilised with a cast |
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Tibial diaphyseal fractures corrected with open reduction |
Displaced reducible fractures with internal fixation |
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Tibial diaphyseal fractures corrected with limited open reduction |
- Displaced reducible fractures with ESF
- Comminuted fractures necessitating cancellous bone graft |
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Tibial diaphyseal fractures corrected with closed reduction |
- Nondisplaced fractures with external coaptation or ESF
- Comminuted nonreducible fractures with ESF |
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Fixation systems applicable to the tibial diaphysis: |
- Casts - IM pins with cerclage wire or ESF support - INterlocking nails - Linear, circular or hybrid ESF - Bone plates |
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Implant use for tibial diaphyseal fracture with FAS of 0-3 |
- Bone plates and screws
- Bone plate and IM pins combo
- Type II ESF
- Interlocking nail |
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Implant use for tibial diaphyseal fracture with FAS of 4-7 |
- Type Ib or Type II ESF
- Bone plate and screws
- Interlocking nail |
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Implant use for tibial diaphyseal fracture with FAS of 8-10 |
- Type Ia ESF
- IM pin and cerclage wire or ESF
- Cast |
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Tibial diaphysis anatomy |
- Craniomedial surface is not covered by muscle
- Extensor muscles on the lateral surface
- Flexor muscles caudal to the tibia
- Medial saphenous artery and vein cross the medial portion of the distal tibia |
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Tibial IM pins |
Must always be placed in a normograde manner, starting at the proximal tibia
Always manipulate the hock to ensure that the pin does not interfere with the joint |
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Tibial bone plates |
Careful contouring of the plate to match the normal configuration of the tibia is essential.
Failure to reproduce the normal curve of the tibia will result in valgus angulation of the limb (lateral). |
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Complications of tibial diaphyseal fractures |
- Osteomyelitis - Implant migration resulting in soft tissue irritation - Malunion, delayed union and nonunion - Cats with rigid ESF may be at risk for delayed healing or nonunion - Pin loosening and pin tract drainage |
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Distal tibia fractures |
- Metaphyseal or epiphyseal fractures
- Fractures/erosions of the malleoi (results in loss of collateral ligament function and talocrural instability)
- Shearing injury of the tarsus may be associated with distal tibial fracture |
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Medical management of proximal/distal tibial fractures |
- Antibiotics for open fractures
- Nondisplaced proximal tibial fractures can be casted
- Analgesics |
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Surgical treatment of proximal/distal tibia |
- IM pins and Steinmann pins or K-wires (crossed) - Buttress plate - Cancellous bone autograft (little ST coverage) - Tension band wire for malleolar fractures to resist the pull of the collateral ligaments - Shearing of hock treated with ESF or synthetic ligament and bivalve cast |
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Tibia and fibula anatomy |
- Lateral aspect covered by the cranial tibial muscle and tendon of the long digital extensor m - Lateral collateral ligament originates from lateral femoral condyle to the fibular head - Peroneal n. and popliteal a. caud. to fibula head - Long and short parts of collateral ligaments from medial and lateral malleolus (hock stability) - Cranial, distal tibia: Cranial tibial T and LDET |
