Design and biomechanical study of slide-poking external fixator for hip fracture

Biomechanical study of extramedullary and intramedullary fixation in the treatment of unstable intertrochanteric reversed-tilt fractures of the femur

Background

To investigate the efficacy of the 135° hip screw, 95° intramedullary hip screw (IMHS) and 95° hip screw in the treatment of intertrochanteric reverse dip fracture of the femur.

Methods

We retrospectively analyzed 125 matched pairs of human femurs (median age 64 years) which were osteotomized at a 33° angle in the left femur and extended downward from the minor trochanter to simulate a reverse oblique intertrochanteric fracture. The right femur served as a control. The left femur (n=4) was implanted with a 135° hip screw, 95° hip screw, or IMHS. A strain detector was placed distal to the fracture site to monitor fragment strain. The lateral displacement of the proximal femur was measured by a linear variable differential transformer. An Instron tester measured stiffness, strain, and lateral displacement at 25° adduction, and 90° adduction with vertical loads on the femoral head. A 2 cm gap was then formed at the fracture site to simulate comminution and the mechanical test was repeated.

Results

Before the formation of the gap, there was no significant difference in stiffness among different bone structures (P>0.05), but after the formation of the gap, the stiffness of all the adduction structures decreased (P=0.03), and the difference in adduction was statistically significant (135° hip screw: 46.6%±3%; 95° hip screw: 22.9%±2%; IMHS: 53.7%±7.8%; P<0.05). Similar results were found for the abduction and buckling positions. There was no significant difference in the lateral displacement of the gap before (P=0.92) and after (P=0.26), but a significant difference in the failure load was found (135° hip screw: 1,222±560 N; 95° hip screw: 2,566±283 N; IMHS: 4,644±518 N; P=0.02).

Conclusions

There was no statistically significant difference in stiffness among different structures (P>0.05). However, in the presence of gaps, IMHS bone implant structures are much stiffer than 135° and 95° structures and have a greater destructive load.

Effect of Anti-Infective Reconstituted Bone Xenograft Combined with External Fixator on Serum CRP and PCT Levels and Prognosis of Patients with Bone Infection after Lower Extremity Long Bone Trauma

Bone infection is one of the common complications of orthopedic surgery. After bone trauma occurs in the human body, the infection of Staphylococcus aureus and Gram-negative bacteria into the fracture area can lead to double infection of the soft tissue and bone tissue at the fracture site, leading to a variety of complications, mostly in the lower extremities. Bone infection easily causes bone destruction, bone nonunion, and bone defect, seriously affecting the quality of life of patients. The traditional treatment method of bone infection is to control the infection first and then repair the bone graft, but this method has a long course, poor efficacy, and high disability rate. In this study, anti-infective reconstituted bone xenograft (ARBX) combined with external fixation was used to treat patients with posttraumatic bone infections of the long bones of the lower extremities, to explore its efficacy, and to analyze its effects on serum CRP, PCT levels, and prognosis. Our results showed that ARBX combined with the external fixator had a good effect on the treatment of patients with bone infection after lower extremity long bone trauma, which could effectively enhance the repair and functional recovery of the limb bone, significantly alleviate the infection degree of patients, reduce the inflammatory response of the body, and have a good prognosis.