The data were collected from 2006 to 2018. A total of 59 acetabular revisions in 58 patients were performed using a TM acetabular component (Trabecular Metal™ Zimmer Biomet, Warsaw, IN, USA) by a single surgeon at our institution. Data were collected retrospectively and prospectively. The retrospective data were collected by using the patients' records, PACS systems for Images and outpatient clinic letters. The prospective data were collected when patients were investigated, diagnosed and treated. No differences in the data were noted.
A total of 245 acetabular revisions were done in our institution during this period by using cemented and uncemented cups available at our institution. The tantalum porous coated shell was used on the basis of the patients' background, the preoperative radiographic findings, the bone loss and the indications for revision surgery.
In our study group, we had 23 males and 35 females. The mean age was 70.11 years (range, 30 to 87 years). Four patients were lost to follow-up and 13 died during the period without having further surgeries attributed to hip arthroplasty. The remaining 41 patients (42 joints) who underwent revision hip arthroplasty had complete data available. All patients were postoperatively clinically and radiologically evaluated, 6 weeks, 6 months and then annually after the operation.
Both porous coated titanium and tantalum shells were available. The tantalum shell was chosen due to its superior properties over tantalum in revision settings [5, 13].
The patients underwent revision surgery by using uncemented trabecular TM acetabular component (Fig. 1). The size of cups used varied from 48 to 56. The screws and augments were used as per the indications. The preoperative planning was done in all the cases for (1) tantalum cup with bone graft and screws and (2) tantalum cup with augments. We used augments in 2 cases.
Thorough intraoperative bone loss assessment was carried out by the surgeon and the autograft/allograft was used to address the defects. The morselised bone allograft was used in 5 patients for autograft was not sufficient. The unconstrained acetabular liners were used in all cases. The head size was matched to fit the acetabular cup to provide the most appropriate stability whilst not compromising the range of motion.
All revisions were performed by the senior author using Southern Moore approach. Most revisions used an incision through the previous scars but if the anterolateral approach was used for the index procedure, a new incision was made to keep with the author’s approach. After achieving adequate exposure and removing the previous component, the periprosthetic membranes and bone tissue were taken and sent for histological and microbiological examinations. The defect and the remaining acetabulum were reviewed and decision was made to use a suitable porous tantalum shell. Then, a graft was used and impacted to fill the defects. After implantation and fixation of the augment, the augment was impacted and secured with additional screws. Postoperatively, full-weight bearing was advised and patients were reviewed in outpatient department at 6 weeks and at regular interval as indicated. The Oxford hip scores were used to measure pre- and postoperative results for all 42 hips (41 patients).
Patients attending clinic were reviewed for LLD discrepancy, complications such as wound infection, deep vein thromboembolism or pulmonary embolism, bleeding, nerve injury and, dislocation. Those who were not able to attend were contacted via phone or correspondence. Patient records were used to ascertain date of index surgery, date of revision surgery, age at revision, perioperative complications such as neurovascular injuries, number of dislocations and further re-revision surgeries. Standard pelvic anteroposterior (AP) radiographs were used to assess and preoperatively classify acetabular defects as per Paprosky classification. Latest radiographs were reviewed by two authors (BC, RB) for osseous integration, subsidence and lucencies (Table 2).
Primary end point was re-revision surgery for any reason. The data were collected for indications, the preoperative Paprosky grades, pre- and postoperative OHS and the postoperative complications. Kaplan-Meier analysis was used to assess tantalum cup implant survival. The revision surgery was used as an endpoint and deaths, loss of follow-up were censored. All P-values ≤0.05 were set as the level of statistical significance and two tailed t-test was used to assess the statistical difference. The data analysis was performed using MedCalc (MedCalc Software Ltd. Belgium) and Windows SPSS software.