Analysis on morphology and stability of femoral hip prosthesis based on the revision operation / 中国骨伤

<p><b>OBJECTIVE</b>According to the information obtained from the revision of total hip arthroplasty, the situations of the artificial femoral stem under physiological stress were analyzed preliminarily. In order to accumulate clinical experience, the discussions about how to enlongate the life of artifical joints were performed.</p><p><b>METHODS</b>Fifty-three patients required revision operations were selected, including 28 males and 25 females,with an average age of 74.66 years old (61 to 84 years old). The average life of artificial joints was 18.24 years (3 to 27 years). The initial weightbearing was started 11 days (5 to 16 days) after the first operation. The main reasons for the revision were the spontaneous loosening and trauma. Based on imaging and surgical findings, as well as the histological pathology, the situations of the stems in human bodies were determined.</p><p><b>RESULTS</b>Femoral prosthesis would sink under physiological stress. The design of femoral stems, motion of patients', and bone growth determined the secondary stability. Straight stems were helpful for physiological subsidence of prosthesis, achieving the stability with close bone-implant contact by bone growth,which allowed the patient to do early landing exercise. The collared prosthesis and prosthesis combined with internal fixation limited the subsidence of femoral stems. Their stability depends on the time of initial placement and the bone growth for supporting. Delaying the inital weightbearing was suggested for patients with these protheses.</p><p><b>CONCLUSION</b>According to the actual situation of the patients, the appropriate chosen of femoral stems and time to perform the weightbearing can extend the life of the femoral prosthesis.</p>

Biomechanical research on upper femur with vertical and bending stress / 中国骨伤

<p><b>OBJECTIVE</b>To study the bone state with ultimate stress by examining biomechanical distribution of upper femur in Chinese, in order to accumulate more experiences for clinical work.</p><p><b>METHODS</b>Totally 60 Chinese femurs from fresh cadavers were randomly divided into two groups. All the femurs were cleaned, and the body age ranged from 36 to 72 years old, averaged 56.4 years, including 41 from males, and 19 from females. These two groups underwent mechanical stress and bending stress tests. Special mechanical laboratory and machines were used to get the information. Results about the loading value at each testing point under stress were collected.</p><p><b>RESULTS</b>The four faces of the upper femur suffered different stress under external forces. The bone on upper femur can tolerate more mechanical stress than bending stress. Medial and lateral region of the femur neck and the rear side of the small tuberosity section were themain position enduring the vertical stress. The rear position of the base femur neck and the small tuberosity section were the main regions enduring the bending stress. Those main positions had strong cancellous bones. The intertrochanteric fracture fixation and artificial femoral stems were designed depending on this biomechanical basis.</p><p><b>CONCLUSION</b>According to our experiment result, doctors need to chose more effective fixations for upper femur fracture, and femoral stems for the patients. More information should be collected by further researches.</p>