What’s the Diagnosis – Case 109
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What’s the Diagnosis – Case 109
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What’s the Diagnosis – Case 109
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What’s the Diagnosis – Case 109
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What’s the Diagnosis – Case 109
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Findings The preoperative study shows severe arthritis of both knees but with varus of the right (medial OA) and valgus of the left (lateral OA). On subsequent imaging there is asymmetry of the polyethylene tray on the radiographs with accompanied slight anterior positioning of the left femur relative to the left tibia. These findings are confirmed on the CT images.
What’s the Diagnosis – Case 109
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What’s the Diagnosis – Case 109
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What’s the Diagnosis – Case 109
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What’s the Diagnosis – Case 109
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Diagnosis: Tibial Tray Spinout Tibial tray spinout is an uncommon but known complication that can occur in the setting of a mobile bearing TKA with a rotating platform. As in this case it is seen much more common in the PCL sparing devices and often in those patients that have a preoperative valgus knee. The dislodging and rotation of the poly tray typically occurs early in the postoperative setting unless the underlying sot tissue envelope is poor in which case it may occur later. The etiology is not completely understood but may relate to necessary gap balancing in the valgus knee. The inciting event is often an adduction movement on a semiflexed knee. Clearly a big key to the diagnosis is the clinician/surgeon having insight that this is the underlying pathology so as to help focus one’s attention on the imaging. As seen here is the change from the normal prominence of the poly tray from anterior to posterior and malalignment of the femur relative to the tibia. Particularly the axial CT images make the rotation of the tray dramatic and conspicuous.
What’s the Diagnosis – Case 109
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References Rotating platform spinouts with cruciate-retaining mobile-bearing knees. Fisher DA, Bernasek TL, Puri RD, Burgess ML. J Arthroplasty. 2011 Sep;26(6):877-82. doi: 10.1016/j.arth.2011.03.007. Epub 2011 May 6.
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