External iliac pseudoaneurysm secondary to medial wall penetration of an acetabular screw: a rare cause of total hip arthroplasty failure 15 years after implantation

Cement fragment induced external iliac artery pseudoaneurysm: a rare complication following total hip arthroplasty

Vascular injury is a rare but important complication following a total hip arthroplasty (THA). The occurrence of such an event can be difficult to detect and manage due to the time frame in which this can occur. We report a case of a female patient in her 70s who presented 19 months post right THA with right-sided acute limb ischaemia. Initial imaging revealed occlusion at the level of the right common and external iliac arteries. The patient was treated with a successful embolectomy, but muscle death in the leg, leading to acidosis resulted in the right leg being amputated. Postoperatively, a drop in the haemoglobin levels without any visible bleeding and the presence of a new suprainguinal pulsatile swelling warranted a CT angiogram. This demonstrated a false aneurysm originating from the distal right external iliac artery, precisely at the point where it encountered a cement spicule from the previous THA.

Intraoperative Radiographic Detection of Intrapelvic Acetabular Screw Penetration: Lessons Learned From Our Trauma Colleagues

BACKGROUND

Intraoperative vascular injury during total hip arthroplasty represents a catastrophic complication. Acetabular screw placement represents one possible mode of injury. The purpose of this study was to evaluate the utility of various fluoroscopic views in the detection of intrapelvic screw penetration.

METHODS

A radiopaque pelvis Sawbones model was instrumented with a hemispherical acetabular component. Four intrapelvic quadrants were defined. Screws were placed, 3 in each quadrant, and imaged sequentially at 3 depths: 0 mm, 5 mm, and 10 mm penetrated. Eight fluoroscopic images were used: anteroposterior, inlet, outlet, iliac oblique, obturator oblique, "down the wing," obturator outlet, and a "quad" view. Three blinded, independent surgeons evaluated the images for intrapelvic screw penetration. Images were analyzed in isolation and as a "triple-shot series" consisting of the "quad," obturator outlet, and iliac oblique views. Sensitivity and specificity values were then calculated.

RESULTS

In isolation, the "quad" view had the highest sensitivity for screw penetration (62%). The triple-shot series was found to be 100% sensitive in all 4 quadrants for detecting 10 mm of screw penetration. The specificity of the series was found to be 100% in all quadrants except for the posterior superior quadrant where it was 67%. Interobserver agreement approached perfection (Kappa ≥0.947) between all surgeons (P < .001) when using the 3-view series.

CONCLUSIONS

This study is the first to assess the use of fluoroscopy in the detection of intrapelvic penetration of transacetabular screws. We found that a 3-radiograph series provided a sensitive and specific metric for the detection of intrapelvic screw penetration.