We are truly grateful for the opportunity to respond to this Letter to the Editor concerning our recently published study entitled “Is older age a contraindication for singlelevel transforaminal lumbar interbody fusion? [1].”

Firstly, as you understand, any surgery when performed in the elderly population is not only subjected to local complications but also to systemic complications. This becomes significant in the elderly who often have multiple comorbidities which pose a higher risk to operative intervention [2]. In this study authors have mentioned comorbidities in quantitative terms (single versus more than two comorbidities), however, no qualitative analysis in terms of type and severity of comorbidities has been performed. The authors believe that this has been one of the limitations of the study. However, all the patients (with single and multiple comorbidities) were considered for the surgery only after thorough clinical, laboratory, and radiological evaluation, proper evaluation of their clinical conditions, and preoperative fitness for surgery. So to better explain this, all the patients (young and elderly—with or without comorbidities) included in the study were preoperatively fit for surgery despite the presence of their clinical condition. The study was basically done to compare the age factor in both the similar groups with the same kind of characteristics and comorbidities.

Secondly, authors have not taken other coexisting causes of low backache into consideration including osteoporosis [3], which might affect the long-term outcome, especially when comparing to a younger population. The authors have included 218 consecutive patients undergoing conventional open transforaminal lumbar interbody fusion (TLIF) for degenerative pathology at L4–L5/L5–S1 levels (degenerative lumbar canal stenosis, prolapsed intervertebral disc, and lytic/degenerative spondylolisthesis). Patients with TLIF other than L4–L5/L5–S1 level, tandem stenosis, revision surgery, trauma, tumor, infection, and multilevel surgeries were excluded. This has been the methodology (to increase the statistical power) of the study to compare the two similar kind groups with similar characteristics except for age. Of course, the authors believe that osteoporosis affects the long-term outcome in the elderly populations; however, the authors have mentioned in the discussion that it was limited with a mid-term follow-up of 2 years.