Answer to the Letter to the Editor of Kalidindi KKV, et al. concerning “Handgrip strength correlates with walking in lumbar spinal stenosis” by Inoue H. et al. [Eur Spine J (2020): DOI 10.1007/s00586-020-06525-1]

[摘要] We appreciate the thoughtful Letter to the Editor regarding our recently published article entitled, “Handgrip strength correlates with walking in lumbar spinal stenosis” [1]. The authors of the letter query why the common causes such as carpal tunnel syndrome (CTS), peripheral neuropathy or joint arthritis were not considered when assessing weak handgrip strength. Most patients with CTS are afected uni‑ laterally; the incidence of unilateral CTS being 74% [2]. Since our study used the best performance, either right or left handgrip strength, any infuence of CTS would likely be negligible. Moreover, the prevalence of CTS is 4.7% (female: 7.2%, male: 1.8%) in the Japanese population aged 50 to 89 years, further depreciating its possible efect [3]. In our study, we had no patients with rheumatoid arthritis or peripheral neuropathy except diabetes. As the authors of the letter point out, other comorbidities including diabetes could afect handgrip strength; so to elucidate this possibil‑ ity we supplemented our results adding Table 3 showing the analysis of non-diabetic patients. Mean and P values of all parameters in the results without diabetes were similar with the results including diabetes, but the correlation coefcients were a little greater. Such conditions as carpal tunnel syn‑ drome, peripheral neuropathy and joint arthritis, had little infuence on the results of our study.