Mid-term follow-up and analysis of the failure cases of interspinous implants for degenerative lumbar diseases

Objective:To assess the indications,efficacy and safety of application of interspinous implants for degenerative lumbar diseases by mid-term follow-up and analysis of the failure cases.Methods: In our study,52 cases of degenerative lumbar diseases treated with interspinous implants From September 2007 to September 2008 were divided into Wallis group(25 cases) and Coflex group(27 cases).The clinical results were assessed by lumbar pain visual analog score(VAS) and lower limber pain VAS,lumbar Japanese Orthopedic Association(JOA) score and Prolo functional score;the radiological results including implant positon,segmental lodosis and segment movement degree were assessed by lumbar X ray post-operation compared with pre-operation.For cases of discogenic low back pain,lumbar disc changes were assessed by lumbar MRI 12 months post operation.Results: Fifty-two cases had complete follow-up and the average time was 30.4 months.In the final follow up,lumbar pain VAS,lower limber pain VAS,lumbar JOA score and Prolo functional score of Wallis group were(2.5±1.7),(2.7±1.4),(23.4±3.1)and(8.9±1.4),which were better than pre-operation(5.3±3.0),(7.4±2.6),(13.5±4.6)and(4.5±2.6),lumbar pain VAS P=0.027,all others P0.001;lumbar pain VAS,lower limber pain VAS,lumbar JOA score and Prolo functional score of Coflex group were(2.6±2.9),(3.8±1.9),(21.2±3.5)and(8.5±1.8),which were better than pre-operation(5.5±3.2),(7.1±2.8),(13.1±4.8)and(4.2±2.5),lumbar pain VAS P=0.036,all others P0.001;in the final follow up,lower limber pain VAS of Wallis group was(2.7±1.4),which was better than(3.8±1.9) of Coflex group(P=0.039);in the final follow up,Segment lodosis angles of Wallis group was 14.3°±3.9°,which was larger than 13.2°±3.5°of Coflex group(P=0.028);Segment movement degree of Wallis group was 9.6°±2.8°,which was smaller than 12.8°±3.0°of Coflex group(P=0.019).In Coflex group,four cases of lumbar disc herniation relapsed and three cases received second operation.One case with lumbar stenosis suffered from lumbar disc herniation of the same segments and received second revision operation.Conclusion: Treatments with interspinous implants for the degenerative lumbar diseases are effective,but we should pay attention to the indication and apply them for lumbar disc herniation with caution.