Abstract
Acute Liner dissociation is a well-documented, but uncommon complication of total hip arthroplasty, yet the journey to diagnosis remains undefined. This clinical case report outlines the use of plain film arthrogram for diagnosis in a 53-year-old female who presented to the ED following a fall, describing symptoms of increasing groin pain, reduced range of movement, difficulty weight-bearing and a grinding sensation in her left hip, all on a background of total hip replacement two years ago. Examination revealed impaired flexion, rotation and abduction while AP pelvic X-ray confirmed mild eccentric placement of the femoral head, and lateral X-ray proved joint enlocation. An arthrogram of the left hip was performed the following day with injection of 4mls of iodinated contrast injected into the joint. Inferior dissociation of the liner from the shell was evident. The femoral head and liner were replaced two days later, and the liner was found to have shearing and gross plastic deformation at the rim. The patient reported immediate relief from the groin pain and was discharged on the fourth day postoperatively. This shows how plain film imaging fails in diagnosing acute liner dissociation dynamic fluoroscopic tests, post-arthrography CT and metal artifact reduction sequence magnetic resonance imaging (MARS MRI) have previously been proposed despite their associated wait-time, radiation exposure and financial costs. This case report highlights the role of plain film arthrography as a low risk and low-cost diagnostic tool. The report also suggests the incorporation of radio-dense markers in liners to facilitate the use of arthrography when diagnosing dissociation, also raising awareness of prevention and recognition in what may be an under-reported complication of hip arthroplasty.
Highlights
Total hip arthroplasty liner dissociation is a diagnosis requiring incisive clinical expertise to differentiate prosthetic hip dislocation from catastrophic implant wear or failure
Liner dissociation has been documented in the literature with various methods of diagnosis being proposed from dynamic fluoroscopy, arthrography and post-arthrography computed tomography (CT), double-contrast CT and metal artifact reduction sequence magnetic resonance imaging (MARS MRI) [1,2]
The apparent infrequency of this complication can result in missed or delayed diagnosis with resultant loosening or destruction of the acetabular cup and or a metallosis reaction necessitating a larger revision procedure than that of early liner dissociation recognition and revision. This case report serves to stress the importance of retaining clinical suspicion of liner dissociation in a patient complaining of audible hip ‘grinding’ combined with plain film radiographs that may be misinterpreted as a hip dislocation
Summary
Total hip arthroplasty liner dissociation is a diagnosis requiring incisive clinical expertise to differentiate prosthetic hip dislocation from catastrophic implant wear or failure. The apparent infrequency of this complication can result in missed or delayed diagnosis with resultant loosening or destruction of the acetabular cup and or a metallosis reaction necessitating a larger revision procedure than that of early liner dissociation recognition and revision This case report serves to stress the importance of retaining clinical suspicion of liner dissociation in a patient complaining of audible hip ‘grinding’ combined with plain film radiographs that may be misinterpreted as a hip dislocation. Differential diagnosis was that of a fracture of the ceramic head, catastrophic liner wear, deep infection or liner dissociation An arthrogram of her left hip was performed the following day in theatre under local anaesthesia. This confirmed needle placement within the joint and femoral head enlocation within the acetabular cup It delineated integrity but inferior dissociation of the polyethylene liner from the Pinnacle acetabular cup component (Figures 3, 4). Her post-operative radiograph is seen in Figure 7 and Figure 8
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