ObjectiveTo evaluate the medium-term effectiveness of Waveflex system in the treatment of multiple lumbar degenerative diseases. MethodsBetween May 2010 and July 2012, 26 patients with multiple lumbar degenerative diseases underwent posterior decompression, transforaminal lumbar interbody fusion (TLIF), and internal fixation with Waveflex system. There were 15 males and 11 females, aged 23-65 years (mean, 34.2 years). The disease duration was 9 months to 8 years (median, 3 years and 3 months). The lesion located at L3-S1. The visual analogue scale (VAS), Oswestry disability index (ODI), and the short-form 36 health survey scale (SF-36) were used to evaluate the status of clinical recovery, meanwhile the Stauffer-Coventry evaluation standard was used to access the satisfaction at last followup; the disc space height (DSH), intervertebral angle (IVA), and range of motion (ROM) were measured on X-ray film or three-dimensional CT, and the adjacent segment degeneration was classified by Pfirrmann score based on MRI findings. ResultsAll patients obtained primary incision healing without nerve injury, cerebrospinal fluid leakage, or internal fixation failure. All patients were followed up 31-50 months (mean, 40.6 months). The VAS, ODI, and SF-36 scores were significantly improved at 6 months after operation and last follow-up when compared with preoperative ones (P<0.05), but no significant difference was found between at 6 months and last follow-up (P>0.05). According to the StaufferCoventry evaluation standard, the results were excellent in 21 cases, good in 2 cases, moderate in 2 cases, and poor in 1 case, with an excellent and good rate of 88.5% at last follow-up. X-ray films showed that there was no complication of screws pulling-out or fixed rod rupture and displacement. At 7 days, 6 months, and last follow-up, the DSH of adjacent segment was significantly increased (P<0.05), and the ROM of adjacent segment was significantly decreased (P<0.05) when compared with preoperative ones; there was no significant difference in IVA between at pre-and post-operation (P>0.05). According to Brantigan grade for fusion, 19 cases were rated as grade E, 6 cases as grade D, and 1 case as grade C, and the fusion rate was 96%. There was no significant difference in Pfirrmann score between at pre-operation and last follow–up (Z=0.000, P=1.000). ConclusionThe Waveflex system combined with TLIF is effective and safe to treat multiple lumbar degenerative diseases during medium-term follow-up.