PMC8328486_01
Preoperative radiographs and computed tomography scan of the left hind limb. (A,B) Craniocaudal (A) and mediolateral (B) radiographic views showing highly comminuted fractures at the proximal femur, including the neck, trochanteric, subtrochanteric, and the proximal half of the diaphysis. (C,D) Volume-rendered computed tomography scan of the cranial (C) and caudoventral (D) views showing the comminuted bones of the neck and trochanter and the comminuted spiral fracture of the proximal half of the femoral diaphysis. The hip joint is confirmed to be intact (white arrowheads).
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F1
A proximal segmental fracture of the left femur and multiple radiopaque objects of various sizes were identified on both plain radiographs and computed tomography scans (Figure 1).
Intraoperative fluoroscopic series showing closed reduction and implant insertion in a 2-year-old cat with a comminuted proximal femur fracture. (A,B) The intramedullary pin is inserted into the trochanteric region, normograde from proximal to distal (A), and it stabilizes the proximal and the distal femoral diaphyseal fragments (B). (C,D) For trans-articular external skeletal fixation of the hip, three of the five positive-profile end-threaded pins are inserted to the left pelvis, including two pins in the ileum (white arrows) and the third pin in the ischium (black arrow), while the other two pins are placed in the distal fragments of the fractured femur (white arrowheads).
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AO forceps and indirect reduction was achieved by applying traction to the distal femur. A small skin incision was made medial to the greater trochanter, and a 2.4-mm Steinmann pin was inserted into the medullary canal of the femur in a normograde fashion (Figure 2A). The intramedullary pin occupied 47% of the medullary cavity at the isthmus (5.1 mm) and stabilized the major diaphyseal segments but not the comminuted femoral neck or the greater trochanter (Figure 2B). Then, one 2.0 mm and one 1.8 mm positive-profile end-threaded pins were also placed perpendicular to the distal femur (Figures 2C,D).
(A,B) Triangular frame composed of connecting bars with epoxy-putty molded pins for trans-articular external skeletal fixation of the hip: the 3.0-mm Steinmann pin (#1, blue dashed line) links the fixation pins placed in the left pelvis (black arrows); the other 3.0-mm Steinmann pin (#2, red dashed line) links to the fixation pins placed in the distal segment of the fractured femur (white arrows); #1 and #2 connecting bars are linked to each other at the intersection; the 2.4-mm Steinmann pin (#3, yellow dashed line) links to the #1 and #2 connecting bars; the other 2.4-mm Steinmann pin (#4, black dashed line) is tied into the intramedullary pin (yellow arrow) and links to the #1 connecting bar. Epoxy-putty covers all the pins composed of connecting bars including column of the pins and those connections.
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The preplaced intramedullary pin was tied into the first connecting rod. The connecting rods were fashioned using 3.0 mm Steinmann pins and epoxy resin (Figures 3A,B).
Postoperative serial radiographic views of the left femur. (A) Lateromedial radiograph acquired immediately after surgery shows good alignment and normal length of the left femur with trans-articular external skeletal fixation of the hip and a tied-in intramedullary pin. (B) On postoperative day 64, periosteal callus bridges the femoral fracture gap with cortical remodeling. Heterogenous opacity of the femoral neck and greater trochanter are identified on the craniocaudal radiographic view (white arrows). Trans-articular external skeletal fixation of the hip is disassembled to the linear tie-in frame by removal of fixation pins in the left pelvis and the associated connecting bars. The connecting bars are cut at the linkage area (green arrows) to preserve the linear tie-in frame. The fixation pin in the ischium is broken and partially embedded in the ischium (black arrow). (C) On day 161, the whole frame of the external skeletal fixation is removed, leaving the intramedullary pin and embedded part of the broken pins (black arrows). Fracture union showing good progression in bone healing is identified as a heterogeneous opacity with a mottled appearance at the femoral head and neck (white arrows).
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PO for 24 h) for analgesia. Postoperative radiographs were taken to verify appropriate placement of the pins and alignment of the femur (Figure 4A). The femoral neck and greater trochanter were remodeling, exhibiting corticalization with heterogeneous opacity (Figure 4B). Additionally, the first and third connecting rods were cut near the area of linkage using a saw and pin cutter, while avoiding impairment of the remaining linear tie-in frame (Figure 4B). Bone resorptions were identified in the femoral head and neck, represented by a mottled appearance of the head and thinning, sclerotic changes of the neck, and the rotational malalignment of the femoral head was confirmed as the head was superimposed over the femoral shaft (Figure 4C). The remainder of the fixator was removed, leaving the intramedullary pin and broken segments of the fixation pins embedded in the bone (Figure 4C).