Short summary

Femoral neck fractures (FNF) represent a substantial challenge to the health care system, and equally important are the personal costs for the patient. By reducing the reoperation proportion and improve the function both the health care system and the patient benefit. Undisplaced FNF are usually treated by internal fixation. Studies show lower complication percentage for hemiarthroplasty compared to internal fixation and suggest a better functional outcome. With this project we intend to conduct a national pragmatical RCT comparing internal fixation with arthroplasties in patients above 65 years with an undisplaced displaced FNF.

Rationale

Arthroplasty for a displaced femoral neck fracture in the elderly is recommend by most guidelines . For the undisplaced, internal fixation (IF) is the only recommendation, however,could there be another choice? 

Recently, a randomized trial (RCT) comparing IF with hemiarthroplasty has been published. The RCT demonstrated a reoperation frequency of 21% in the IF group and 5% in the hemiarthroplasty group but also a better hip function after 6 and 12 months in favour of hemiarthroplasty. The study is severely underpowered lacking a clear primary outcome. Furthermore, a mortality less than 10% after 1 year suggests a highly selective group. An ongoing RCT comparing IF with hemiarthroplasty for the undisplaced FNF demonstrated similar results with 24% reoperations in the IF group and 7% in the hemiarthroplasty group. The primary outcome was Harris Hip Score (HHS) which did not show any difference after 1 year but the there was a better Timed Up and Go test in favour of hemiarthroplasty. HHS may not be the best primary outcome due to the ceiling effect and lack of validation for hip fracture patients. Both RCTs do seem to find better mobilisation in favour of hemiarthroplasty and a register study have also demonstrated lower pain and more satisfaction with hemiarthroplasty for displaced FNF compared to undisplaced FNF with internal fixation. This is probably due to shortening of the femoral neck which is not seen when surgery is performed using an arthroplasty. However, the external validity problems of traditional RCTs and bias/confounding problems from cohort studies make the provided evidence limited for everyday clinical use.

Mobilization after hip fracture is perhaps the most important factor for mortality after surgery and the surgery should therefore aim for fast mobilization. An arthroplasty may therefore be the best choice but a cohort studie has demonstrated a higher mortality percentage when using hemiarthroplasty compared to internal fixation (9). The study has severe bias issues and the groups may not be comparable. One of the best ways to investigate the mobility seems to be the de Morton Mobility Index (DEMMI), and it has been validated in hip fracture patients (10, 11). DEMMI provides a valid method for measuring and monitoring the mobility for patients making the transition from hospital to home (12). If we are to investigate a difference in functional outcome and secondary in mortality for undisplaced FNF when comparing internal fixation with arthroplasty, then we need a large scale pragmatic RCT in order to have sufficient external validity.

The purpose is to compare arthroplasty with internal fixation for functional outcome in patients above 65 years with a low energy undisplaced displaced femoral neck fracture.

Description of the cohort

 Age 65 years or above, undisplaced femoral neck fracture (Garden type 1 and 2), posterior tilt (14) less than 20 degrees, low energy, NMS (15) = 5 and above, indicating an ability to walk, cognitive intact in order to achieve informed consent. 

Data and biological material

Demographics: Age, sex, residency.

Comorbidity: ASA classification by anaesthesiologist on call, Charlson Comorbidity Score and medication.

Admission: Time from admission to surgery, duration of hospital stay, concurrent infection, fracture time

Operation: duration of surgery, quality of implant insertion, type of implant, surgical experience.

Blood: Blood count at admission and discharge, blood loss during surgery, blood transfusions.

Reoperations, postoperative complications (infections, thromboembolic events, implant related complications), readmissions, infections (pneumonia and urinary tract infection) and mortality.

The primary outcome measure is DEMMI. Secondary outcome measure evaluated at the same time points is the Oxford Hip Score (OHS), Euro-Qol 5 domain (EQ-5D-5L), reoperation and mortality. Explorative outcome measures are NMS, age, x-ray measurements, and activity tracking.

Collaborating researchers and departments

Deparment of Orthopedics, Aalborg University Hospital

• Professor Søren Kold

Department of Orthopedics, Aarhus University Hospital

• Consultant Ole Brink, PhD

Department of Orthopedics, Odense University Hospital

• Professor Hagen Schmal

Department of Orthopedics, Slagelse Hospital

• Kristoffer Hare, MD, PhD

Department of Orthopedics, Bispebjerg Hospital

• Associate Professor Henrik Palm MD, PhD