PMC9148226_01
The pelvic radiographs demonstrate dislocation of left total hip replacement, protrusio acetabuli, formation of pseudoarthrosis, and gross loosening of the screw cup. No signs of loosening or fracture of the Zweymuller type femoral stem. Incidental femoral stent on the left.
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fig1
This demonstrated left hip dislocation, migration of acetabular component, and formation of pseudoarthrosis within the left ilium (Figure 1).
(a) Intraoperative photo of the acetabulum with the trial cup in situ in the original hip center. Large secondary spherical bone defect evident overlying the previous pseudoarthrosis. (b) Intraoperative photo using three tantalum augments and cementing them together in a "football configuration." (c) Intraoperative photo showing the tantalum augments in situ filling the cranial acetabular defect. Underneath, we see the cemented Mark III cup with the ceramic head.
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Type IIIb defect (Figure 2(a)). There were spherical acetabular defects over the true acetabulum and another spherical acetabular defect overlying the debrided pseudoarthrosis. A novel method of acetabular reconstruction involves using three tantalum augments and cementing them together in a "football configuration" using regular bone cement (polymethylmethacrylate, PMMA) (Figure 2(b)). A compatible Delta ceramic head size 28 x 3, 0 mm (Biolox , CeramTec, Plochingen, Germany) was placed on the original stem and achieved stable range of motion of the hip (Figures 2(c) and 4).
Preoperative planning using cemented Mark III cup.
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Reconstruction of the acetabulum to achieve a physiological center of rotation was achieved using a cemented Mark III acetabular cup (Waldemar Link Company, Hamburg, Germany) according to preoperative planning (Figure 3).
Follow-up X-ray demonstrating left hip dislocation at 4 weeks postop.
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Last X-ray of the patient in clinic after the cemented cup revision. No further episodes of left hip dislocation.
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Thus, the cemented cup was revised 4 weeks after the initial reconstruction with an elevated liner and installed an antidislocation ring (Figure 6).