Harrington Rod Revision After Failed Total Hip Arthroplasty Due to Missed Acetabular Metastasis
We report the case of a 61-year-old woman who was referred to our service after she received a total hip implant at another institution and was found to have a large acetabular defect from pulmonary metastasis. The patient elected to undergo palliative surgical curettage and fixation. We describe a technique to create a cement construct reinforced with Steinmann pins that reduces pain and offers improved mobility.
In addition, a few cases have been reported of metastases to endoprostheses, which were implanted long before the diagnosis of cancer.10 To an unsuspecting surgeon, the lytic periprosthetic metastases may look like osteolysis or pseudotumor. Fabbri and colleagues11 presented 4 cases showing how sarcoma around a joint endoprosthesis can easily be mistaken for pseudotumor. A patient considering primary or revision THA for bone loss caused by osteolysis would be given different options than if the bone loss were secondary to metastases. Revision techniques in the setting of acetabular osteolysis include acetabular liner exchanges, cementless hemispherical components and jumbo cups, structural allografts, metal augments, impaction grafting, and acetabular cages and cup-cage constructs. Rarely are “Harrington” reconstructions performed for this reason.12
This case is unusual because the diagnosis of metastatic disease was missed and THA was performed under the presumptive diagnosis of osteoarthritis. While a malignant process was recognized intraoperatively, the joint replacement was completed nonetheless, with revision surgery inevitably occurring within a few weeks. Our patient’s history of lung cancer reinforces the importance of preoperative history taking, and the missed diagnosis highlights the need for clinicians to maintain a broad differential, even in seemingly simple arthritis cases. Proper preoperative imaging, biopsies, and cultures are also paramount. Lesions that are painful, involve the whole cortex, appear soon after implementation, and are rapidly progressing should raise concern for malignancy.10 If there is concern for osteolysis, quantitative CT with 3-dimensional reconstructions can help visualize the lesions and help in planning surgery.13 Had a timely diagnosis been made, the proper reconstruction could have been planned before the index procedure, and our patient could have been spared the pain, risk, and morbidity of a second operation.
The second lesson of this case is that, as long as the cup was stable, the etiology of the hip pain was lack of mechanical support. Once corrected, the total hip functioned as planned. A minimally invasive approach that allowed for observation of the cup without exposing the entire hip saved a patient a significant amount of morbidity and led to an acceptable outcome.
