We evaluated patients with LDD using the FRAIL scale and discovered that the Frail patients had considerably poor lumbar paraspinal muscle morphology and more significant fatty infiltration than the non-Frail patients. There doesn’t appear to be any past research similar to this study.
Paraspinal muscles play an essential role in maintaining the normal shape of the spine [18], and its composition is closely related to spinal diseases, including LBP, lumbar disc herniation (LDH), LSS, spondylolisthesis and spinal imbalance, and the prognosis of spinal surgery [19]. Fortin et al. found that multifidus muscle FI and psoas relative CSA are associated with functional status in patients with LSS [10]. A systematic review conducted by Jermy et al. confirmed an association between low multifidus fat infiltration on MRI at baseline and greater reductions in measures of LBP and disability following surgical treatment [20]. Tang et al. indicated that patients with degenerative lumbar scoliosis had asymmetric degeneration of the paraspinal muscles and psoas major. The CSA and FI of the multifidus are closely correlated with the quality of life [21]. Some LSS and coexisted with sagittal imbalanced patients were reported to restore their normal sagittal morphology only through simple decompression or limited decompression and fusion surgery [9, 22, 23]. However, these studies have shown that patients with relatively stronger paraspinal muscle mass could restore normal spine alignment after surgery.
Through the regression analysis, we found that besides sex, frailty has the greatest influence on fCSA among these factors, and it is a risk factor for fCSA of the paraspinal muscles. Frailty also has the most significant impact on FI% of the paraspinal muscles among these factors. In other words, frail patients would have smaller fCSA, and a greater fatty infiltration rate in paraspinal muscles, which means a worse paraspinal muscle morphology. From the regression analysis, it can be found that only the FI% of MF has a significant effect on frailty, which means that the patients with greater MF FI% would be more likely to suffer from frailty. Therefore, frailty and morphology of paraspinal muscle would affect each other, frailty will worsen the paraspinal muscle’s morphology, and poor paraspinal muscle morphology is a risk factor for frailty. This suggests that strengthening paraspinal muscle exercise would be helpful to improve the frail status of patients. Moreover, considering the critical role of paraspinal muscles in maintaining the curve of the spine and its close relationship with lumbar degenerative diseases, it is also vital to remedy the frail status in LDD therapy. Therefore, assessment of the muscle mass presents important clinical implications before developing a treatment plan. In this study, only asked a few simple questions and could make a preliminary judgment on the condition of a patient's paraspinal muscles. It is self-evident that it brings convenience to surgeons and low cost to patients in clinical work.
Frailty is a condition characterized by the progressive deterioration of physiological functioning, which is closely related to adverse events such as falls, decreasing mobility, hindrances in the activities of daily life, hospitalization, and deaths [24]. Frailty leads to physical deterioration and reduced mobility. Therefore, lacking exercise and motion, the process of muscle degeneration in frail patients would be more severe than in those not [25]. Martino et al. found that intramuscular lipid concentration increased in localized regions of the lumbar muscles following 60-day bed rest [26]. Previous studies have shown nutritional risk factors were independently associated with physical pre-frail/frail condition [27]. However, poorer nutritional status is significantly associated with sarcopenia [28]. As a result, it also explains why the paraspinal muscles of Frail patients are worse than non-Frail patients.
The FRAIL scale was published by Morley et al. and used to assess frailty, which has been demonstrated as an excellent screening test for clinicians to identify frail persons at risk of developing disability as well as a decline in health functioning and mortality [14, 24]. Although MRI is more accurate in assessing paraspinal muscle mass, it has the disadvantage of being time-consuming, labor-intensive, and expensive. Additional extensive, multi-dimensional frailty screening scales and prospective study protocols could be utilized in future investigations to determine the validity and reliability of this conclusion.
There are still some limitations that should be considered. First, the characteristics of the research cohort cannot be typical of the general population because we only included relatively small Chinese senior patients. Second, this is only a retrospective study, and other prospective results are needed to support the clinical relevance and implications. Finally, the current study used a basic frailty screening tool to evaluate the influence of the frailty state on the paraspinal muscle’s morphology. Compared with other complex or multidimensional scales, the FRAIL scale lacks a certain amount of relative accuracy. However, its convenience could save a lot of time and boost the efficiency of clinicians.