Purpose: To determine whether body mass index (BMI) is associated with mis-seating of ceramic acetabular components, and whether any associations are independent of differences in case mix.

Method: All primary total hip arthroplasty (THA) cases using ceramic components, identified from a prospective database of total joint arthroplasties performed at one center among six surgeons between 1998–2006 were radiographically reviewed. The risk of mis-seating by BMI was calculated using logistic regression models.

Results: Of the 411 THAs, 77 (20.3%) were performed in patients with BMIs that were defined as underweight to normal BMI (29.9 BMI). THA mis-seating occurred in 80 cases (19.5%). Intra-operative characteristics differed significantly according to THA mis-seating status. Univariate analysis revealed that THA mis-seating was more likely to occur in procedures performed by certain surgeons (2 trend, p = 0.01) and procedures performed in more recent years (2 trend, p = 0.02). In comparison with patients who did not incur a mis-seated THA, those patients who did incur a mis-seated THA did not have a significantly different trend in BMI (c2 trend, p = 0.09). However, adjustment for case mix, THA type, surgeon and year of procedure revealed a significant association between BMI and risk of THA mis-seating. Those patients who were overweight at the time of THA (BMI of 25.0–29.9) were at increased risk of THA mis-seating (adjusted odds ratio (OR) 2.52, 95% confidence interval (CI) 1.24–5.12, p = 0.01).

Conclusion: THA mis-seating of ceramic acetabular systems was a frequent occurrence. Although incidence of mis-seated THAs did not differ significantly by patient sex, hip side, indication, or THA component type, mis-seating did differ significantly by surgeon and year of replacement. Furthermore, patients who were overweight were more than two times more likely to suffer THA mis-seating than those who were underweight, of normal weight or obese.

Bone metastases from renal cell carcinoma are aggressive, osteolytic lesions that often require operative intervention for fracture prophylaxis, fracture fixation or palliation. The lesions are hypervascular and intraoperative bleeding is a serious challenge for the orthopaedic surgeon. The purpose of this study was to determine the efficacy of preoperative tumour embolization in reducing blood loss during operative management of renal cell carcinoma metastases to bone.

Patients were identified from a prospectively accumulated database (1996–2006). Inclusion criteria included operative management for renal cell metastasis to the pelvis or appendicular skeleton. Patients that were not embolised preoperatively due to renal insufficiency or obesity were excluded. Embolizations were performed the day of surgery by an interventional radiologist. Post-embolization runs were used to determine the percentage of blood flow reduction to the tumour. Variables analyzed included patient age, gender, location of tumour, surgical procedure, surgical time, number of units of packed red blood cells (PRBC) transfused, estimated intraoperative blood loss (EBL) and percentage embolised according to the post-embolization run. Student’s t-test was used to determine the effects of percentage embolization on EBL and number of units of transfused PRBCs.

Thirty-five cases (twenty-eight patients) met the inclusion criteria. There were twenty males and eight females with an average age of sixty-five years (range, forty-three to eighty-nine years). The most common metastatic sites were the femur (nineteen cases), humerus (seven cases) and pelvis (six cases). There were ten cases of intramedullary nailing and twenty-five cases of tumor resection and reconstruction. Average surgical time was 4.5 hours (range, 0.75–10 hours) and average EBL was 1.5 litres (range, 0.25–12 litres). Embolization that successfully blocked at least 75% of the blood flow to the tumour significantly decreased surgical EBL (3.2 vs 0.6 litres, P< 0.05) and units of PRBCs transfused (5.6 vs 1.9, P=0.05) compared to those that did not. Two embolization-associated complications occurred including one case of toe gangrene and one case of muscle ischemia.

Preoperative embolization significantly reduces blood loss and red blood cell transfusions resulting from surgical stabilization of renal cell metastases to bone. Close communication between the orthopaedic surgeon and interventional radiologist is imperative to maximise these benefits.