case_images: PMC8164530_01
case_images: Plain radiograph obtained at the initial visit of a 78-year-old man, showing severe heterotopic ossification around the left hip joint.
case_images: CRIOR2021-8849929.001.jpg
case_images: PMC8164530_01_CRIOR2021-8849929.001.jpg
case_images: fig1
case_images: On initial examination at our hospital, plain radiographs revealed hip joint ankylosis, with evidence of severe HO (Brooker IV) around the hip joint and loosening of the acetabular cup (Figures 1 and 2).
case_images: Three-dimensional computed tomography images showing severe heterotopic ossification around the hip joint and loosening of the acetabular cup in a 78-year-old man.
case_images: CRIOR2021-8849929.002.jpg
case_images: PMC8164530_01_CRIOR2021-8849929.002.jpg
case_images: fig2
case_images: On initial examination at our hospital, plain radiographs revealed hip joint ankylosis, with evidence of severe HO (Brooker IV) around the hip joint and loosening of the acetabular cup (Figures 1 and 2).
case_images: (a) Plain radiograph obtained immediately after the revision THA (second THA) in a 78-year-old man. Abbreviations: THA: total hip arthroplasty. (b) Owing to limited surgical field for a joint revision procedure in a 78-year-old man, using the standard approach because of hip ankylosis, the cement and polyethylene liner were placed onto the acetabulum after impaction of the new head.
case_images: CRIOR2021-8849929.003.jpg
case_images: PMC8164530_01_CRIOR2021-8849929.003.jpg
case_images: fig3
case_images: With no evidence of loosening of the femoral stem and considering the difficulty of performing THA in the presence of hip ankylosis, we did not replace the femoral stem (Figure 3(a)). Specifically, we implanted a new metal femoral head, applied vancomycin-mixed cement to the acetabulum, and inserted and fixed a polyethylene liner into the narrow space between the metal head and the acetabulum on the unhardened cement (Figure 3(b)).
case_images: (a) Plain radiograph of a 78-year-old man obtained prior to the third THA, showing a clear zone around the cemented cup. Abbreviations: THA: total hip arthroplasty. (b) Plain radiograph of a 78-year-old man obtained immediately after the third THA, showing the initial gap between the host bone and the allograft in zones 2 and 3. We used vancomycin-mixed cement and replaced the cup and cemented stem simultaneously via a single-stage exchange. (c) Plain radiograph of a 78-year-old man obtained at the final follow-up (3 years postoperatively) examination with the gap between the host bone and allograft persisting in zone 3, with no evidence of prosthesis loosening.
case_images: CRIOR2021-8849929.004.jpg
case_images: PMC8164530_01_CRIOR2021-8849929.004.jpg
case_images: fig4
case_images: We planned a second revision surgery (third THA), via a posterior approach, to remove the remaining HO from the posterior hip joint (Figure 4(a)) and replace the femoral stem to control the infection. We used vancomycin-mixed cement and replaced the acetabular cup and femoral stem simultaneously via a single-stage exchange, considering the mild nature of the infection and the patient's preferences (Figure 4(b)). Further, plain radiographs did not reveal evidence of worsening HO (Figure 4(c)) compared with that on the radiograph obtained immediately after the third THA (Figure 4(b)).