To study the correlation between sagittal angle of femoral prosthesis implantation and the wear and rear of femoral prosthesis in senile total knee arthroplasty.

Eighty elderly patients who underwent total knee replacement in Beijing Geriatric Hospital from January 2015 to January 2016 were selected for a retrospective study. All the patients received total knee replacement. According to whether the patients had abnormal wear and fracture of the tibial plateau polyethylene gasket column in the medium and long term, the patients were divided into the observation group requiring revision (14 cases) and the control group (66 cases). Standard lateral radiographs of the knee were taken within three days, six months and three years after the surgery, and the beta(β) angle between the cortical line of the anterior femur and the anterior malleolus line of the femoral prosthesis was measured. The β angle and the degree of knee flexion at each time point after the surgery were compared between the two groups by t test. Pearson correlation analysis was used to observe the correlation between the β angle and the duration of knee prosthesis.

The β angle of the observation group was higher than that of control group at three days, six months and three years after the operation (t=10.085, 31.037, 57.945, all P<0.05). Three years after surgery, knee flexion in the observation group was significantly lower than that in the control group, and the difference was statistically significant (t =4.699, P<0.05). The β angle was negatively correlated with the duration of knee prosthesis use (r=-0.765, P<0.05), but not correlated with the degree of long-term knee flexion (r=-0.397, P>0.05).

The placement angle of femoral prosthesis in sagittal plane is an important factor affecting the long-term wear of prosthesis in the elderly patients undergoing total knee replacement.