INTRODUCTION. Although surgical treatment for degenerative lumbar diseases is well established and many reports of favorable surgical outcomes have been published, the impact of posterior lumbar surgery on sarcopenia has not yet been fully reported. In this study, we investigated postoperative muscle mass changes measured by dual-energy X-ray absorptiometry (DXA) and clinical outcomes in sarcopenic patients who underwent posterior decompression or posterior intervertebral fusion for degenerative lumbar diseases.
METHODS. 159 patients (69 males and 90 females, mean age 73.5±6.42) who had undergone surgery for lumbar degenerative diseases aged 60 years or older at our hospital from April 2021 to March 2022 were included. Of these, 64 patients underwent lumbar decompression surgery (39 males and 25 females, mean age 74.3±5.84) and 95 patients (30 males and 65 females, mean age 73.3±6.94, 27 PLIF and 68 TLIF) underwent lumbar intervertebral fusion. Neurological disease, infection, and reoperated cases were excluded. We evaluated trunk muscle mass, fat mass, and skeletal muscle mass index (SMI) measured by DXA, and for clinical outcomes, visual analogue scale (VAS) for low back pain and Oswestry Disability Index (ODI) preoperatively and one year postoperatively. The Asian Working Group for Sarcopenia 2019 criteria were used to divide the patients into sarcopenia group (S group) and non-sarcopenia group (NS group), and further into decompression group and intervertebral fusion groups for comparison. The χ2 test and Mann-Whitney U test were used for statistical treatment, with a significance level of p<0.05.
RESULTS. The S group consisted of 25.2% (40 patients, mean age 78.0±6.5) and the NS group consisted of 74.8% (119 patients, mean age 72.3±5.9); the S group was significantly older than the NS group (P<0.001), but postoperative SMI was significantly higher (P=0.031). Furthermore, preoperative ODI and RDQ were significantly lower in the S group (P<0.001, P=0.0047, respectively), but postoperatively showed good improvement similar to the NS group. Although SMI was also significantly reduced when trunk muscle mass was reduced postoperatively (P<0.001), there was no difference in surgical outcomes. In addition, a comparison of the decompression and intervertebral fusion groups showed no difference in trunk muscle mass, fat mass, SMI changes, or clinical outcomes before and after surgery.
DISCUSSION. Sarcopenic patients with lumbar degenerative diseases had preoperative ADL decline, but there was an increase in limb skeletal muscle mass postoperatively, and surgical outcomes were comparable to those of non-sarcopenia patients. Posterior lumbar decompression or intervertebral fusion may be a useful treatment, especially for sarcopenic patients.