HA-coated pins improve external fixation of pertrochanteric fractures

Issue: Issue 2 2004

Italian flag Using an external fixator with hydroxyapatite-coated pins was an effective technique for treating femoral pertrochanteric fractures in patients with osteoporotic bone at the Rizzoli Ortopedico Instituto in Bologna, Italy.

In a study comparing the Orthofix Pertrochanteric Fixator (OPF) with dynamic hip screws (DHS), the OPF was associated with stable fixation, less blood loss and no pin track infections. At the six-month follow-up, however, there were no significant differences in functional results for patients treated with either technique.

“OPF with hydroxyapatite-coated (HA) pins is an effective and safe treatment option for osteoporotic pertrochanteric fractures,” said Antonio Moroni, MD, who presented results of the randomized comparative study at the Orthopaedic Trauma Association 19th Annual Meeting in Salt Lake City, U.S.A.

External fixation was once a viable treatment option for pertrochanteric fractures, but it became less popular when users reported cases of insufficient mechanical resistance of the fixator and significant rates of pin track infection. Moroni and his co-investigators speculated that using HA-coated pins with a fixator that allowed the femoral head pins to converge or be parallel might help maintain fracture reduction and result in fewer complications.

The condition of the pin tracks can be seen in this photograph taken at the time one patient’s fixator was removed. Investigators said pin care is typically not problematic.

COURTESY OF ANTONIO MORONI

The 40 patients studied were women at least 65 years old with low bone mineral density (ie, contralateral hip T score less than -2.5). Fractures were AO type A1 or A2. Patients were randomized for treatment with DHS or OPF. The DHS, which had four holes and a 135° angle, was fixed with standard AO/ASIF screws. Investigators used four 5-mm to 6-mm HA-coated pins with the OPF, two each in the femoral head and proximal shaft.

Patients were permitted to bear weight as tolerated. At three months, postop, investigators removed the fixators.

The researchers evaluated several factors, including femoral shaft neck angle, pin track infections in the OPF group, length of hospital stay and reduction quality. They found blood loss was greater in the DHS group, with patients receiving two postoperative transfusions, on average. No patient in the OPF group required a transfusion (P<.0001). Operative time was twice as long in the DHS group.

OPF-treated patients had less pain at five days’ postop. “At six months, a significantly higher fracture varization was seen in the DHS group,” Moroni said. DHS varization was 668; it was 261 in the OPF group (P=.002).

Investigators theorized that no pin track infections occurred due to the use of HA-coated pins and their superior purchase in the osteoporotic bone, which helped minimize loosening.

“Pin extraction torque was higher than pin insertion torque. This is an important result because it shows that HA-coated pins were well-fixed even in osteoporotic bone, and this fixation improves over time,” Moroni said.

For more information:

Moroni A, Faldini C, Pegreffi F, Giannini S. External fixation revisited: a new treatment option for elderly patients with trochanteric fractures. #20. Presented at the Orthopaedic Trauma Association 19th Annual Meeting. Oct. 9-11, 2003. Salt Lake City, U.S.A.