Effect Of Technique With And Without Screw On Stability Of Cup In Total Hip Arthroplasty

Objective Compare the resultions in stability of total hip arthroplasty with and without acetabular screws. Observed the changes of the position of the acetabulum in the two groups after operation weight-bearing.Method From 2008 to 2011, follow-up 60 patients who operated total hip replacement with cementless acetabular cup, a total of 62 hip. The average follow-up time was 24 months. According to whether implanting intraoperative acetabular screws or not, they are divided into two groups. "A" group with 32 hips was implanted intraoperative acetabular screws. "B"with 30 hips was not implanted intraoperative acetabular screws. Assessing the changes in imaging and the Harris scores between the tow groups to compare the stability of the acetabulum and clinical effects.Results Observed the image changes of the bone around the acetabular component during the 24 months. In total 62 hips, 32 cases were implanted 1-2 screws above the Cl area of acetabular. On the contrary,30 patients were with no screws. By assessing the time periprosthetic appearred obvious gaps,bone sclerosis and radiolucent lines to assess the effects of surgery. In B group, we can often find spaces in C2 zone on the X-ray photographs after 6 days operatively(7 hips,23.33%). Gaps disappeared after 24 months later. In A group C2 zone had less space after surgery (1 hip, 3.12%). In B group,15 hips (46.88%) had bone sclerosis in C1 zone within 5 months after the operation. With the emergence of bone sclerosis from 5 to 24 months, radiolucent line were found in the C3 zone in 10 hips (31.25%).8 (25.00%) hips were fuond radiolucent line in C1 zone within 16 months after operation. The B group were rarely found radiolucent line and bone sclerosis in the C1 and C3 zone after operation. Comparing the changes of acetabular abduction angle and median acetabular center of rotation between the two groups to assess the effects of surgery. Two groups of patients after operation the abduction angle and rotation center position changes in the value of the difference was not statistically significant (P> 0.05). The late follow-up, the average Harris score of A group was (93.7±2.0) points, the average Harris score of B group was (95.3±1.5) points, the difference was not statistically significant.B group, the average operation time was 58.50±5.22minutes;A group, the average operation time was75.56±8.89 minutes, the difference was statistically significant (P <0.05). B group, the average blood loss was 162.5ml (range 100-300ml), A group, the average blood loss was 387.5ml (range 300-500 is), the difference was statistically significant (P<0.05). To the end of follow-up, no patient had prosthesis dislocation.Conclusion There was no significant difference in clinical effect and acetabulum position between no screw group and postoperative acetabular screw group, but the image changes of without screws group is less occurring Around the acetabular cup, so it is not necessary to implant screws in total hip arthroplasty. Also concluded that weight-bearing walking after 1 week will not lead to fixation of cup without screw displace, the role of stress is more conducive to bone ingrowth. We can applicate the press-fit technology to obtain the internal stability of acetabular cups without screws, making less blood loss, shorter operative time.