PMC7276565_01
The first image demonstrates the skin ulceration due to chronic sinus formation and drainage. The white arrow shows the sinus tract.
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F1
On admission, the patient had no fever, and the sinus showed a rather mild secretion (Fig. 1), the erythrocyte sedimentation rate (ESR) was elevated to 68 mm/h (normal limits: 0-20 mm/h), the C-reactive protein (CRP) was 3.2 mg/dL (normal limits: 0-0,5 mg/dL), and the white blood cell count was 8.14 K/muL (normal limits: 4-10 K/muL), while the neutrophils were 4.63K/muL (normal limits: 2-7,5 K/muL).
Initial radiograph of hips and pelvis, demonstrating the complete horizontal migration of the Zweymuller total hip arthroplasty (THA) components without disassembly. Findings of sclerotic femoral bone are evident indicating possibly chronic osteomyelitis. The black arrow shows the bone remodeling, the green arrow the osteolytic lesions and the yellow the sclerotic bone. The mild intrapelvic migration of the contralateral THA is also obvious.
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F2
On admission, the initial plainroentgenograms of the hip disclosed sclerotic and osteolytic lesionsin both femur and acetabulum, with perforations through the lateral and medial cortices of the proximal femur, and migration of the Zweymuller stem together with the screw socket and ball head to a 90  horizontal position in relation to the longitudinal femoral axis on the frontal plane of the whole prosthesis (Fig. 2).
Axial computed tomography on admission demonstrates the location of the cup on the left image (the white arrow shows the adductors muscles and the black arrow shows the cup underneath the subcutaneous tissue), while the right image demonstrates the location of the stem (the green arrow shows the perforating lateral femoral cortex and the yellow arrow the medial side).
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F3
The proximal one-third of the femur was perforated by the stem in both medial and lateral cortices (Fig. 3). CT angiography revealed the proximity of the screw socket to the superficial branch of the common femoral artery (Fig. 4). Through a short longitudinal incision above the dislocated THA, the cup and the femoral ball head were found without disassembly (Fig. 5).
Coronal computed tomography angiography demonstrates that the cup of the hip arthroplasty locates medially close to the superficial branch of the common femoral artery (the green arrow shows the artery, while the yellow arrow shows the horizontally migrated hip prosthesis).
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F4
The proximal one-third of the femur was perforated by the stem in both medial and lateral cortices (Fig. 3). CT angiography revealed the proximity of the screw socket to the superficial branch of the common femoral artery (Fig. 4). Through a short longitudinal incision above the dislocated THA, the cup and the femoral ball head were found without disassembly (Fig. 5).
Intraoperative image demonstrates the removal of the cup (right image) and the stem with the ball head (left image) from the medial side.
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F5
The proximal one-third of the femur was perforated by the stem in both medial and lateral cortices (Fig. 3). CT angiography revealed the proximity of the screw socket to the superficial branch of the common femoral artery (Fig. 4). Through a short longitudinal incision above the dislocated THA, the cup and the femoral ball head were found without disassembly (Fig. 5).
Intraoperative image demonstrates the infected soft tissue after blue methylene administration on the lateral side. The black arrow shows the perforation of the lateral femoral cortex. Excessive debridement was performed on the lateral side based on the blue methylene diffusion, while excision of the scar and the fistula was also held.
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F6
Traces of tissue metallosis but no pseudotumor were found intraoperatively (Fig.6).
Post-operative anterior-posterior hip radiogram shows the resection arthroplasty with satisfactory imaging.
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F7
The final radiographic result was a resection arthroplasty (Fig. 7). Our patient had followed up, at 3 and 12 months postoperatively, with negative inflammation markers, no sinus formation, and satisfactory clinical and radiographic evaluation (Fig. 7).