Abstract Background and purpose: To evaluate the clinical efficacy of Dynaloc^®, a new implant for fixation of femoral neck fractures, which comprises 3 cancellous screws fixed in a small side plate. Patients and methods: Patients older than 50 years with fresh femoral neck fractures were randomly allocated to osteosynthesis with Dynaloc^® or cancellous screws. The primary endpoint was leg length discrepancy due to femoral neck shortening. The secondary endpoints were WOMAC, EQ-5D, and Harris hip scores after 12 months as well as the fracture healing properties, all reoperations, and adverse events after 24 months. Results: Mean patient age was 71.9 (SD 11.8) years; 60% were women. Fracture types were mainly Garden I and II. No significant differences in the primary or secondary endpoints between the Dynaloc^® and cancellous screw groups were observed. Seventeen patients experienced at least one reoperation: in the Dynaloc group 2 patients had THA and 5 had the implant removed additionally one patient developed infection requiring operation, in the screw group 4 had an arthroplasty (1 HA and 3 THA) and the implants were removed in 5. Avascular necrosis of the femoral head was verified in three patients in the Dynaloc^® group. Conclusion: A firm conclusion cannot be drawn from this study because of small numbers, but we found no differences in terms of limb length and other outcome measures between the groups at one year, which cannot justify the use of Dynaloc^® due to the frequent complications related to the implant.
Keywords: hip fracture; cancellous screws; Dynaloc^®; implant removal