Posterior lumbar interbody fusion using nonresorbable poly-ether-ether- ketone versus resorbable poly-l-lactide-co-d,l-lactide fusion devices: A prospective, randomized study to assess fusion and clinical outcome

STUDY DESIGN.: A prospective randomized clinical study. OBJECTIVE.: To assess fusion, clinical outcome, and complications. SUMMARY OF BACKGROUND DATA.: Resorbable poly-l- lactide-co-d,l-lactide (PLDLLA) cages intended to aid spinal interbody fusion have been introduced into clinical practice within the last decade. Although early case series show promising results with respect to fusion rate, worries persist with regards to efficacy and potential risks of early failure of these implants. Despite widespread clinical application this is the first randomized prospective study to assess clinical and radiologic outcomes of PLDLLA cage compared with a traditionally applicable counterpart. METHODS.: Twenty-six patients were randomly assigned to undergo instrumented posterior lumbar interbody fusion whereby either a nonresorbable poly-ether-ether-ketone (PEEK) cage or a resorbable PLDLLA cage was implanted to aid fusion. Fusion rate, subsidence, and clinical outcome based on visual analog scale scores for leg pain and back pain, as well as Oswestry Disability Index and SF-36 questionnaires were documented and analyzed. Complications and adverse events were recorded. RESULTS.: Fusion rate was significantly higher with the PEEK cage compared with PLDLLA cage (Fisher exact test, P = 0.0302). Rate of subsidence was significantly higher with the PLDLLA cage compared to PEEK cage (Fisher exact test, P = 0.0414). The PEEK group demonstrated greater improvement in the Oswestry Disability Index compared with the PLDLLA group (Fisher exact test, P = 0.1414). Two cases of mild to moderate osteolysis were seen in the PLDLLA group. CONCLUSION.: Our results strongly suggest that PLDLLA cage proffers a lower rate of fusion compared with PEEK cage, and also confirms that the efficacy of PLDLLA cage in enhancing interbody spinal fusion is yet to be established. The higher rate of subsidence and occurrence of osteolysis seen in association with PLDLLA cages in this study remain worrisome.