Report On Midterm Results With Kyphosis Correctionand And Height Restoration Effects Of Percutaneous Vertebroplasty: Over Five Years Follow-up

Objective: To evaluate the effects and the risk factors of kyphosis correction and height restoration after percutaneous vertebroplasty.Methods: PVP was performed in 106 consecutive patients of OVCF with 211 vertebrae involved(T6-L4). The cases that follow-up over five years were analyzed retrospectively. The cement distribution in the vertebra, cement volume injected were recorded. The anterior, middle, posterior vertebral heights and the kyphosis angle were measured preoperative , post operative and at follow-up. Vertebrae were assigned to groupV1 (cement volumes equal or more than 15% of the vertebral body volume) and groupV2(cement volumes less than 15% of the vertebral body volume ), Vertebrae were assigned to group D1(the cement distribution in the vertebrae is good: cement spread across median line in anterior-posterior view and from anterior to posterior part in lateral view), the others were assigned to group D2(the cement distribution in the vertebrae is bad). The anterior body height, middle height, posterior height and the Cobb angle at preoperative compared with those after the operation and at the follow-up.Result: 69 cases(117vertebrae)of them were followed up for 5.0–8.5 years (mean 5.9 years), Case follow-up rate 65%, Vertebral follow-up rate 55.5%. groupV1: 107 vertebrae, groupV2: 10 vertebrae , group D1: 97vertebrae , group D2: 20 vertebrae . The average anterior body height of groupV1 was 18.326±6.291mm before procedure , 21.588±5.515mm after procedure, and 20.999±5.621mm at follow-up. GroupV2 was 18.208±4.871mm , 21.400±3.782mm , and 17.133±3.81mm respectively. GroupD1 was 18.248±6.283mm before vertebroplasty and 21.498±5.525mm after vertebroplasty and 21.113±5.591mm at follow-up. GroupD2 was 18.562±5.682mm before vertebroplasty and 21.837±4.713mm after vertebroplasty and 18.629±5.157mm at follow-up. There were significant difference of anterior height at preoperative compared to the postoperative in four groups . It is significantly different between postoperatively and at follow-up in group V2 and group D2. There is no significant difference in group V1 and group D1 between postoperatively and at follow-up(P>0.05). For middle body height of groupV1 was 16.028±5.68mm before procedure , 20.395±4.927mm after procedure, and 19.611±5.13mm at follow-up. GroupV2 was 16.028±5.68mm , 19.100±2.487mm, and 17.175±2.68mm respectively. GroupD1 was 16.063±5.65mm before vertebroplasty and 20.470±4.937mm after vertebroplasty and 19.802±5.03mm at follow-up. GroupD2 was 15.350±4.905mm before vertebroplasty and 19.458±3.896mm after vertebroplasty and 17.662±4.492mm at follow-up. There were significant difference of anterior height at preoperative compared to the postoperative in four groups . It is significantly different between postoperatively and at follow-up in group V2 and group D2. There is no significant difference in group V1 and group D1 between postoperatively and at follow-up(P>0.05). The average posterior body height of groupV1 was 26.685±4.878mm before procedure, 27.387±4.5mm after procedure, and 27.090±4.654mm at follow-up. GroupV2 was 26.125±2.85mm, 26.741±2.845mm, and 26.183±3.131mm respectively. GroupD1 was 26.797±4.811mm before vertebroplasty and 27.445±4.477mm after vertebroplasty and 27.173±4.61mm at follow-up. GroupD2 was 25.975±4.298mm before vertebroplasty and 26.841±3.892mm after vertebroplasty and 26.316±4.172mm at follow-up. There is no significant difference in four groups between preoperatively and postoperatively, postoperatively and at follow-up(P>0.05). The kyphotic deformity of groupV1 was 27.126±14.67 degree before the operation, 15.543±11.574 degree after the operation, and 15.923±12.681 degree at follow-up. GroupV2 was 26.833±13.279 degree, 11.166±6.589 degree, and 18.750±8.214 degree respectively. GroupD1 was 26.868±14.928 degree before vertebroplasty and 15.197±11.853 degree after vertebroplasty and 15.652±13.051 degree at follow-up. GroupD2 was 27.958±12.875 degree before vertebroplasty and 12.750±6.961 degree after vertebroplasty and 19.000±8.521 degree at follow-up. There were significant difference of kyphosis angle at preoperative compared to the postoperative in four groups . It is significantly different between postoperatively and at follow-up in group V2 and group D2. There is no significant difference in group V1 and group D1 between postoperatively and at follow-up (P>0.05).Conclusions: 1. Percutaneous vertebroplasty is effective for restoring vertebral body height and kyphotic angle to the ovcf. 2. It can decrease the risk of vertebral body height loss secondarily after vertebroplasty if the bone cement injected is more than 15% of the vertebral body volume. 3. The unsatisfied distribution of bone cement in vertebral body can increase the risk of vertebral body height loss after vertebroplasty.