Take Home Points
- IAF is an uncommon, but serious complication of primary THA.
- Small (<50 mm) cups are at higher risk for causing IAF.
- Prompt recognition is critical to prevent component migration and need for revision.
- Posterior column integrity is cirtical to a successful outcome when IAF occurs.
- Initial stable fixation, with or without intraoperative acetabular revision, is critical for successful outcome when IAF is identified.
Intraoperative acetabular fracture (IAF) is a rare complication of primary total hip arthroplasty (THA). 1-3 IAFs commonly occur with impaction of the acetabular component. Studies have found that underreaming of the acetabulum and impaction of relatively large, elliptic, or monoblock components may increase the risk of IAFs. 2-5 There is a paucity of literature on risk factors, treatment strategies, and outcomes of this potentially devastating complication.
In this article, we report on the incidence of IAF in primary THA at our high-volume institution and present strategies for managing and preventing this rare fracture.
Materials and Methods
Between 1997 and 2015, more than 20 fellowship-trained arthroplasty surgeons performed 21,519 primary THAs at our institution. After obtaining Institutional Review Board approval for this study, we retrospectively searched the hospital database and identified 16 patients (16 hips) who sustained an IAF in primary THA. Mean age of the cohort (13 women, 3 men) at time of surgery was 70 years (range, 42-89 years). Of the 16 patients, 13 had a preoperative diagnosis of osteoarthritis, 2 had posttraumatic arthritis, and 1 had rheumatoid arthritis. A posterolateral approach was used with 14 patients and a modified anterolateral approach with the other 2. Surgical technique and implant selection varied among surgeons. Thirteen THAs were performed with an all-press-fit technique and 3 with a hybrid technique (uncemented acetabular component, cemented femoral component). In 9 cases, the acetabular component underwent supplemental screw fixation. Whether to use acetabular component screws or cemented femoral components was decided intraoperatively by the surgeon.
The cohort’s acetabular components were either elliptic modular or hemispheric modular. The elliptic modular component used was the Peripheral Self-Locking (PSL) implant (Stryker Howmedica Osteonics), and the hemispheric modular components used were either the Trident implant (Stryker Howmedica Osteonics) or the ZTT-II implant (DePuy Synthes). Elliptic acetabular components have a peripheral flare, in contrast to true hemispheric acetabular components. Ten elliptic modular and 6 hemispheric modular components were implanted. In all cases, the difference between the final reamer used to prepare the acetabular bed and the true largest external diameter of the impacted shell was 2 mm or less.
The cohort’s 16 femoral components consisted of 8 Secur-Fit uncemented components (Stryker Howmedica Osteonics), 3 Accolade uncemented components (Stryker Howmedica Osteonics), 3 Omnifit EON cemented components (Stryker Howmedica Osteonics), and 2 S-ROM uncemented components (DePuy Synthes).
After surgery, all patients were followed up according to individual surgeon protocol for radiographic and physical examination.
Data on IAF incidence were obtained from a hospital database and were confirmed with electronic medical record (EMR) documentation. Also obtained were IAF causes and locations recorded in operative notes. For fractures identified after surgery, location was obtained from the immediate postoperative radiograph. Fracture management (eg, supplemental screw fixation, fracture reduction and fixation, bone grafting, acetabular component revision, protected weight-bearing) was determined from EMR documentation.
Sixteen patients sustained an IAF in primary THA. All IAFs occurred in cases involving cementless acetabular components. The institution’s incidence of IAF with use of cementless components was 0.0007%.
Of the 5 IAFs (31%) identified during surgery, 4 were noted during impaction of the acetabular component, and 1 was noted during reaming. Eighty percent of these IAFs occurred directly posterior, and 60% were addressed at time of index procedure secondary to acetabular component instability. The other 11 fractures (69%) were identified on standard postoperative anteroposterior pelvis radiographs obtained in the postanesthesia care unit (PACU). Details of component characteristics, fracture location, immediate treatment, and weight-bearing precautions for all 16 patients are listed in the Table.The radiographs of patients 4 and 9, who were initially treated with observation, are presented in Figures 1A-1C and 2A-2C .
There were additional complications. One patient sustained an intraoperative proximal femur fracture, which was addressed at the index THA with application of a cerclage wire and reinsertion of the femoral component; no further surgical intervention was required, and the femur fracture healed uneventfully. Another patient had a postoperative ileus that required nasogastric tube decompression and monitoring in the intensive care unit; the ileus resolved spontaneously. A third patient, initially treated with bone grafting and