Type of Implant and Risk of Fracture in Total Hip Arthroplasty

The Influence of Stem Type (Dorr) and Femoral Fixation on Outcomes Following Total Hip Arthroplasty for Acute Femoral Neck Fractures: A Multicenter Study

Summary

Background

The American Academy of Orthopedic Surgeons guidelines report moderate evidence for cementing femoral stems for hip fractures, primarily derived from the hemiarthroplasty literature . This is the first large unregistered study to examine the influence of femoral fixation, implant type, patient characteristics, and radiographic factors on outcomes after total hip arthroplasty (THA) for acute femoral neck fractures.

Methods

A multicenter retrospective study of 709 cases of THA (199 cemented, 510 uncemented) for femoral neck fractures was conducted between 2006 and 2020 at three large academic institutions. Demographic data, perioperative characteristics, and radiographs were reviewed. Kaplan-Meier survival curves were generated for multiple outcomes. Univariate and multivariate analyzes were performed with P ≤ 0.05 indicating significance.

Results

Uncemented stems had a higher rate of all-cause aseptic femoral revision (5.1 versus 0.5%, P = 0.002) and periprosthetic femoral fracture rate (4.3 versus 0%, P = 0.001) .

Each successive Dorr type had a higher fracture rate with cementless implants: 2.3%, 3.7%, and 15.9% in Dorr A, B, and C, respectively (p < 0.001). Logistic regression analyzes confirmed that cementless stems (P = 0.02) and Dorr C bone (P = 0.001) are associated with periprosthetic fractures; collared implants and prophylactic wires did not protect against fractures. There was no difference in rates of dislocation, septic revision, or mortality between the groups.

Comments

Increased risk of fracture after total hip replacement when a cementless implant is used to treat femoral neck fracture

A study by the Hospital for Special Surgery (HSS) and other centers found that total hip replacement performed with a cementless prosthesis for a femoral neck fracture led to a higher rate of a second fracture and subsequent revision surgery . The research was presented today at the annual meeting of the American Academy of Orthopedic Surgeons (AAOS) in Las Vegas. The results were also published online in The Journal of Arthroplasty .

Treatments for a femoral neck fracture range from non-surgical management to total hip replacement. When hip replacement is the best treatment option, it can be performed with or without bone cement to secure the prosthesis.

"Femoral neck fractures are very common in the elderly and are a major cause of morbidity and mortality in this population," explained Alexander McLawhorn, MD, orthopedic hip and knee surgeon at HSS and author of the study. “Several national registry studies have demonstrated a lower risk of general revision surgery, and specifically periprosthetic fracture revision, with cemented femoral fixation. Despite this overwhelming data, many patients in the United States receive cementless fixation, including patients who have suffered femoral neck fractures.”

"To our knowledge, this was the first unregistered study to compare the outcomes of cemented versus cementless total hip replacement for acute femoral neck fractures and examined the influence of several patient factors, including bone quality," Michael explained. Kheir, MD, who presented the study at the AAOS meeting and played a leading role in the research during his fellowship at HSS. “The primary objective was to compare complication rates between both groups, including periprosthetic fractures, aseptic revision, dislocation, and mortality rates.” Dr. Kheir is currently an orthopedic surgeon specializing in hip and knee replacement at the University of Michigan.

The retrospective study analyzed 709 total hip replacement cases (199 cemented, 510 uncemented) for femoral neck fractures between 2006 and 2020 at three large academic institutions: Hospital for Special Surgery, Indiana University Health, and University Hospitals Cleveland Medical Center. Patient demographics, perioperative characteristics, and radiographs were reviewed. The Dorr classification system, widely used to evaluate femoral bone quality, classified patients as having Dorr type A, B, or C, with type C indicating the weakest bone.

The average age of study participants was 71 years; 66.9% of the patients were women. The prevalence of Dorr type bone was 21.1% type A; 66.3% type B; and 12.6% type C. Patients who received cemented implants were older, had a lower BMI, were more often female, and were more likely to have a pre-existing diagnosis of osteoporosis and Dorr C bone type.

Uncemented implant stems had a higher all-cause aseptic femoral revision rate (5.1 vs. 0.5%) and periprosthetic femoral fracture rate (4.3 vs. 0%). Bone grading played an important role: each successive Dorr grade had a higher fracture rate with cementless implants (Dorr A = 2.3%; Dorr B = 3.7%; Dorr C = 15.9%). There was no difference in rates of dislocation, revision for infection, or mortality rate between the groups. The study found an equal distribution of male and female patients who suffered a fracture.

“While femoral fractures occurred in patients of all types of bone quality, the Dorr C stem was particularly prone, with an alarmingly high fracture rate when cementless stems were used,” Dr. Kheir noted. “All fractures requiring revision surgery occurred in uncemented cases , suggesting that cemented stems may minimize this complication, regardless of patient sex or Dorr classification.”

Authors : Alexander McLawhorn, MD, MBA; Emile-Victor Kuyl, BS, (HSS); George Ochenjele, MD, FAAOS, (UH Cleveland Medical Center); Jacob Speybroeck, MD; Julian Dilley, MD, (Indiana University Health); Michael M. Kheir, MD, (University of Michigan); R M. Meneghini, MD, FAAOS, (Indiana University Health Phys)