Static Proximal Fixation of Intramedullary Nails Used to Treat Intertrochanteric Femur Fractures Does Not Increase the Risk of Failure. Radiographic Outcomes From a Randomized Controlled Trial.

OBJECTIVES

To compare the outcomes of intramedullary fixation of intertrochanteric femur fractures treated with a single lag screw (Gamma3) and a dual integrated screw design (Intertan), including outcomes depending on the mode of proximal lag screw fixation (static or dynamic).

DESIGN

A pragmatic, single-blinded RCT with a three-arm parallel group design.

SETTING

A multicenter PRCT, with a Level 1 academic trauma center and a second linked smaller level 2 hospital.

PATIENT SELECTION CRITERIA: Patients older than 60 years undergoing intramedullary screw fixation of a standard obliquity intertrochanteric femur fracture (AO/OTA 31A1 or A2) were randomized into 3 groups: single lag screw (dynamically locked), dual integrated lag screw (dynamically locked), and dual integrated lag screw (statically locked).

OUTCOME MEASURES AND COMPARISONS: The primary outcome measure was radiographic failure of the device by 6 months, judged by any one of cut-out requiring reoperation, a change in tip-apex distance of more than 10 mm, or breakage of the metal. Pairwise comparisons were performed between the 3 study groups. Secondary outcomes included all cause reoperation rates and degree of secondary collapse.

RESULTS

A total of 477 patients were randomized. 27 patients were excluded after randomization and 95 died before 6 months. 226 had full follow-up to the primary outcome point of 6 months: (80 Gamma, mean age 83 (range 60-101), 60% female; 72 Intertan dynamic, mean age 80 (range 60-101), 63% female; 74 Intertan static, mean age 82 (range 61-97), 72% female). A further 129 had clinical follow-up but no radiographs. No difference was seen in radiographic failure by 6 months between the Gamma nail (single lag screw) and the Intertan Dynamic (dual lag screw) groups (11.3% vs. 9.7%, P = 0.74); Initial tip-apex distance remained statistically the most significant independent predictor of failure (mean TAD of 15.7 mm in the nonfailure group, 23 mm in the failure group, P < 0.001). The Intertan group with a statically locked proximal lag screw had a lower (nonstatistically significant) radiological failure rate (1.4%) than either dynamically locked group (Gamma 11.3%, Intertan dynamic 9.7%, P = 0.05). Reoperation rates were similar for all groups (Intertan static 2%, Gamma 3.3%, Intertan dynamic 5.3%, P = 0.42).

CONCLUSIONS

In patients older than 60 years undergoing intramedullary fixation of standard obliquity intertrochanteric fractures, the failure rate was not higher when using the Intertan nail in the proximally locked mode, when compared with either the Intertan nail or Gamma nail used in the dynamic proximal locking mode.

LEVEL OF EVIDENCE: Therapeutic Level II. See Instructions for Authors for a complete description of levels of evidence.