Comparison of Long‐Term Outcomes between the n‐HA/PA66 Cage and the PEEK Cage Used in Transforaminal Lumbar Interbody Fusion for Lumbar Degenerative Disease: A Matched‐Pair Case Control Study

Objective The nanohydroxyapatite/polyamide‐66 (n‐HA/PA66) cage is a novel bioactive nonmetal cage that is now used in some medical centers, while the polyetheretherketone (PEEK) cage is a typical device that has been widely used for decades with excellent clinical outcomes. This study was performed to compare the long‐term radiographic and clinical outcomes of these two different cages used in transforaminal lumbar interbody fusion (TLIF). Methods In this retrospective and matched‐pair case control study, we included 200 patients who underwent TLIF from January 2010 to December 2014 with a minimum 7‐year follow‐up. One hundred patients who used n‐HA/PA66 cages were matched with 100 patients who used PEEK cages for age, sex, diagnosis, and fusion level. The independent student's t ‐test and Pearson's chi‐square test were used to compare the two groups regarding radiographic (fusion status, cage subsidence rate, segmental angle [SA], and interbody space height [IH]) and clinical (Oswestry Disability Index [ODI], and Visual Analog Scale [VAS] for back and leg) parameters preoperatively, postoperatively, and at the final follow‐up. Results The n‐HA/PA66 and PEEK groups had similar fusion rates of bone inside and outside the cage at the final follow‐up (95.3% vs 91.8%, p = 0.181, 92.4% vs 90.1%, p = 0.435). The cage union ratios exposed to the upper and lower endplates of the n‐HA/PA66 group were significantly larger than those of the PEEK group ( p < 0.05). The respective cage subsidence rates in the n‐HA/PA66 and PEEK groups were 10.5% and 17.5% ( p = 0.059). There were no significant differences between the two groups in the SA, IH, ODI scores, or VAS scores at any time point. The n‐HA/PA66 group showed high fusion and low subsidence rates during long‐term follow‐up. Conclusion Both n‐HA/PA66 and PEEK cages can achieve satisfactory long‐term clinical and radiographic outcomes in TLIF. However, the n‐HA/PA66 group showed significantly larger cage union ratios than the PEEK group. Therefore, the results indicated that the n‐HA/PA66 cage is an ideal alternative material comparable to the PEEK cage in TLIF.