Design and clinical application of new type two-head automatic pressure external fixation (TAPEF) / 中国骨伤

<p><b>OBJECTIVE</b>To design a new type two-head automatic pressure external fixator and explore its clinical effects in treating intertrochanteric fracture of the femur.</p><p><b>METHODS</b>Base on unilateral angulated external fixator and Ilizarov techiques, a new type two-head automatic pressure external fixator were designed and made. From October 2006 to December 2010, 120 patients with intertrochanteric fracture of the femur were treated with the new type two-head automatic pressure external fixator. There were 67 males and 53 females with an average age of 76.7 years (ranged, 60 to 93 years). According to Evans classification, type I was in 65 cases, type II in 41, type III a in 10, type III b in 2 and type IV in 2. Operative time was from 0 to 11 days after injury with an average 5 days. Postoperative functional recovery was evaluated according to criteria of Sanders.</p><p><b>RESULTS</b>Among 120 patients, 116 cases were followed up with an average of 12 months (ranged, 2 to 24 months). All fractures obtained healing with average healing time of 12 weeks (ranged, 10 to 13 weeks). Five cases occurred with superficial infection of pin site and no deep infection,non-union, coxa adducta were found. Joint function of hip recovered well. According to Sanders scoring, pain, walking, function, muscle strength, daily activities and X-ray estimate were respectively (9.07 +/- 0.41), (9.23 +/- 1.00), (9.42 +/- 1.10), (9.31 +/- 1.06), (9.22 +/- 1.03), (10.00 +/- 0.00) with total amount of (56.27 +/- 4.16). A hundred and six cases got an excellent results, 6 good, 4 poor.</p><p><b>CONCLUSION</b>The new type two-head automatic pressure external fixator is easy and convenient to apply in operation. It has duplicate functions of load and minimal invasive. It is an ideal method for treatment of the intertrochanteric fracture of the femur in high-risk and senile patients.</p>

Biomechanical study of new type two-head automatic pressure external fixator (TAPEF) for the treatment of intertrochanteric fracture / 中国骨伤

<p><b>OBJECTIVE</b>To investigate the mechanical characteristics of new type two-head automatic pressure external fixator in the view of biomechanics.</p><p><b>METHODS</b>Fifteen fresh and humid specimens were selected and divided into experimental group (5 cases) and control group (10 cases). The control group were respectively applied with DHS (5 cases) and traditional external fixator (5 cases). In order to compare the different apparatus, the strength, stiffness and twist mechanical function of femoral intertrochanteric fracture with different device were measured respectively when the specimens were under the pressure of 0-1800 N and loading speed 1.4 mn/min.</p><p><b>RESULTS</b>The strength, stiffness, twist mechanical function and maximum endurance of femora in the experimental group were obviously superior than that of DHS and traditional external fixator (P < 0.05).</p><p><b>CONCLUSION</b>Two head automatic new type pressure external fixator can embed more tightly without sliding, also can prevent the occurrence of coxa vara effectively.</p>