The periprosthetic femur fracture. A study from the Swedish National Hip Arthroplasty Register

Abstract: Post-operative periprosthetic femur fracture is a severe complication after total hip arthroplasty (THA).The incidence of periprosthetic femur fractures seems to be increasing because of several factors,including a growing population with THAs and an increasing life expectancy. Furthermore, after fourdecades of THA surgery, the number of patients with revised THAs has also risen. Periprosthetic femurfracture is more common after revision surgery.The overall aim was to study the postoperative/late periprosthetic femur fracture in a nationwideprospective study and to estimate the national incidence. Other aims of this study were: 1. To identifypatient related risk factors associated with sustaining a late periprosthetic femur fracture. 2. To identifyimplant related risk factors associated with sustaining a periprosthetic femur fracture. 3. To evaluatepatient related outcome after treatment of a periprosthetic fracture by the use of generic and diseasespecificinstruments. 4. To describe the treatment and analyze failure rate using the need of further surgeryas failure endpoint definition. 5. To identify implant and patient related risk factors associated with failureof treatment for a periprosthetic fracture.The Swedish National Hip Arthroplasty Register is a unique instrument concerning studies ofuncommon complications after THA surgery. The current study is, to our knowledge, the largest reportedmaterial (1,049) of postoperative/late periprosthetic femur fractures. The annual incidence ofperiprosthetic femur fracture varied between 0.045% and 0.13%, and increased towards the end of the studyperiod.Between 1979 and 2000, 1,049 periprosthetic femur fractures were reported to The Swedish NationalHip Arthroplasty Register. We analyzed the correlation to diagnosis, gender, implant type, stem fixation,and time interval from index operation to fracture. Patients operated from 1999 to 2000 (321) werefollowed prospectively. A clinical follow-up was done (mean 2.5 years) at each local hospital and a Registryfollow-up (mean 5 years) with re-operation as an endpoint was performed. By use of the Poissonregression model we identified risk factors associated with periprosthetic fracture and risk factorsassociated to failure.A majority of the patients had a loose stem at the time of fracture. These findings stress theimportance of longitudinal clinical and radiographic follow-up of patients operated on with a THA.Female gender and osteoarthritis were associated with a decreased risk while age, rheumatoid arthritis andhip fracture had an increased risk for sustaining a periprosthetic fracture. In the revised group thestrongest predictor was the number of revisions performed before the fracture. The anatomically shapedLubinus SP II prosthesis had a significantly decreased risk, and patients with the Charnley or the Exeterprostheses had significantly increased risk for periprosthetic fracture.Patients operated for a periprosthetic femur fracture had on average a poor clinical outcome at 2.5years follow-up both concerning the health related quality of life and the hip specific assessment. Highfrequencies of major complications and re-operations were found. Approximately every fifth patient wasin need of further surgery during the study period and 50% of them were re-operated on within 12months post-operatively. The 5-year survivorship with re-operation as failure endpoint was 74.8 ±5%.The general poor results after surgical treatment of periprosthetic femur fractures indicate the need offurther studies in this field.