Predicting life expectancy is not an exact science. But estimating the remaining years of life in elderly patients with a femoral neck fracture may help orthopaedists determine whether to use unipolar or bipolar hemiarthroplasty components when surgically managing that population. So suggest Farey et al. in the February 3, 2021 issue of The Journal of Bone & Joint Surgery.
The relevant “magic number” for life expectancy after femoral neck fracture is 2.5 years. The authors arrived at that number by performing statistical analyses on nearly 63,000 cases of femoral neck fractures treated with either modular unipolar or bipolar hemiarthroplasty. Patients were in their early 80s on average at the time of surgery. The researchers focused on revision rates because reoperations in this vulnerable group of patients typically yield poor results.
There was no between-group difference in overall revision rate within 0 and 2.5 years after the procedure. However, unipolar hemiarthroplasty was associated with a higher overall revision rate than bipolar hemiarthroplasty beyond 2.5 years after surgery (hazard ratio [HR], 1.86).
Farey et al. also drilled down into reasons for revision and found that unipolar prostheses had a greater risk of revision for acetabular erosion, particularly in later postoperative time periods. Conversely, bipolar hemiarthroplasty was associated with a higher risk of revision for periprosthetic fracture, which the authors surmise might have arisen from the greater range of motion (and therefore activity levels) permitted by bipolar implants.
Although the authors did not perform a formal cost-benefit analysis related to this dilemma, they observed a nearly $1,000 USD price difference between the most commonly used bipolar and unipolar prostheses. Farey et al. therefore propose that the more expensive bipolar prosthesis may be justified for patients with a life expectancy beyond 2.5 years, but that the unipolar design is justified for patients with a postoperative life expectancy of ≤2.5 years.
Click here to listen to a 15-minute OrthoJOE podcast about this topic, featuring JBJS Editor-in-Chief Dr. Marc Swiontkowski and OrthoEvidence Editor-in-Chief Dr. Mo Bhandari.
Click here to see a 3-minute Video Summary of this study.
Click here to read a JBJS Clinical Summary comparing total hip arthroplasty with hemiarthroplasty for displaced femoral neck fractures.
Total hip arthroplasty (THA) is a tried-and-true treatment for debilitating hip osteoarthritis. But as the number of patients undergoing THA continues to rise, so does the incidence of periprosthetic femoral fractures and the need for revision surgery. The increasing burden of periprosthetic fractures has led to the development of shorter-stemmed femoral components that theoretically preserve bone, decrease fracture risk, and make revision surgery easier if it is required. In the January 6, 2021 issue of The Journal, Slullitel et al. report on a randomized controlled trial that determined whether bone loss differed between patients who received a conventional stem and those who received a short, bone-preserving stem over 2 years following THA.
Forty-six patients received the short, proximally porous-coated stem (Depuy Synthes Tri-Lock bone-preservation stem), and 40 received the conventional stem (Depuy Synthes collarless Corail stem). The primary outcome–bone mineral density (BMD)–was analyzed at 12, 26, 52, and 104 weeks after surgery with dual x-ray absorptiometry region-free analysis (DXA-RFA), which revealed pixel-level resolution of BMD at the bone-implant interface.
Immediately after surgery, researchers found a similar amount of bone loss in both groups in the calcar region and the cancellous portion of the distal greater trochanter. But at all other subsequent time points, bone loss was significantly greater in patients with the bone-preserving stem (analysis of variance [ANOVA] p < 0.0001). In addition, over the full study period the small areas of bone gain that the researchers found were statistically greater in the conventional-stem group than in the Tri-Lock group. Notably, patient-reported outcomes and adverse events did not differ between the 2 groups at the 2-year follow-up.
These early results cast a shadow of doubt over whether a stem that is marketed to preserve bone actually accomplishes that objective. However, 2 years is a very short follow-up when looking at the lifetime of a hip arthroplasty, and the clinical implications of these findings will become clearer with longer-duration analysis.
Click here to read a JBJS Clinical Summary titled “Short-Stem Femoral Components in THA” by Tad Mabry, MD.
Matthew R. Schmitz, MD
JBJS Deputy Editor for Social Media
In 1922, Kellogg Speed, MD said in his American College of Surgeons address, “We enter the world under the brim of the pelvis and exit through the neck of the femur.” Since then, it has been repeatedly shown that femoral-neck and intertrochanteric hip fractures are associated with a high mortality rate during the first year following fracture. Now, in the era of widespread hip arthroplasty—and with the consequently increasing rates of periprosthetic fractures near the hip joint—it is relevant to ask whether periprosthetic fractures are associated with an increased risk of mortality similar to that seen after native hip fractures. In the April 4, 2018 issue of The Journal, Boylan et al. use the New York Statewide Planning and Research Cooperative System database to address that question.
The authors reviewed 8 years of native and periprosthetic hip fracture data to determine whether the 1-month, 6-month, and 12-month mortality risk between the two patient cohorts was similar. They found that the 1-month mortality risk in the two groups was similar (3.2% for periprosthetic fractures and 4.6% for native fractures). However, there were significant between-group differences in mortality risk at the 6-month (3.8% for periprosthetic vs 6.5% for native) and 12-month (9.7% vs 15.9%) time points.
This makes clinical sense because, in general, patients experiencing a native hip fracture have lower activity levels and general fitness and higher levels of comorbidity than patients who have received a total hip arthroplasty. Extensive research has resulted in protocols for lowering the risk of mortality associated with native hip fractures, such as surgery within 24 to 48 hours, optimizing medical management through geriatric consultation, and safer and more effective rehabilitation strategies. We need similar research to develop effective perioperative protocols for patients experiencing a periprosthetic fracture, as this study showed that 1 out of 10 of these patients does not survive the first year after sustaining such an injury. I also agree with the authors’ call for more research to identify patients with periprosthetic fractures who are “at risk of worse outcomes at the time of initial presentation to the hospital.”
Marc Swiontkowski, MD