Setscrew distal locking for intramedullary nails: a biomechanical study.

Area of Science:

• Orthopedic biomechanics
• Trauma surgery
• Implant design

Background:

• Femoral shaft fractures require stable fixation for effective healing.
• Intramedullary (IM) nails are a common treatment, but distal fixation methods vary.
• Evaluating novel fixation techniques is crucial for improving patient outcomes.

Purpose of the Study:

• To biomechanically assess the effectiveness of setscrew distal locking in static IM femoral nails.
• To compare the stability of setscrew fixation against conventional interlocking and non-locked IM nails.
• To determine the torsional and axial mechanical properties of different distal locking methods.

Main Methods:

• Fifteen cadaveric femora were divided into three groups: conventional interlocking, setscrew, and no distal locking.
• Nails were inserted, and femora were subjected to torsional and axial compression tests using a servohydraulic machine.
• Data on torque, stiffness, energy capacity, and displacement were collected and analyzed.

Main Results:

• The conventional interlocking group demonstrated significantly higher maximum torque at 20 degrees of rotation compared to the setscrew and non-locked groups (p < 0.05).
• Torsional stiffness was comparable between the setscrew (87% of interlocking) and interlocking groups (p > 0.05).
• Axial compression tests showed similar maximum shortening and stiffness between the interlocking and setscrew groups (p > 0.05).

Conclusions:

• Distal setscrew fixation provides adequate biomechanical stability for IM femoral nails in treating femoral shaft fractures.
• This fixation method offers comparable torsional and axial rigidity to conventional interlocking screws.
• Setscrew distal locking is a viable option for stabilizing femoral nails during the postoperative rehabilitation phase.