Lumbar Posterior Muscle and Local Kyphosis in Patients with Degenerative Thoracolumbar Kyphosis: A Case-Control Study

Abstract

Purpose: To explore the relationship between thoracolumbar kyphosis (TLK), body mass index (BMI) and the content of lumbar posterior muscles in patients with degenerative thoracolumbar kyphosis (DTLK) combined with lumbar stenosis syndrome (LSS).Methods: 126 patients with DTLK and LSS (DTLK group) and 87 patients with simple LSS (control group) were retrospectively included with well-matched demographics. TLK and lumbar lordosis (LL) were obtained on the X-ray of the whole spine. Lumbar crossing indentation value (LCIV) was introduced to evaluate the content of the lumbar muscles, with was measured from T12-L1 to L4-L5 at T2-MRI axial imaging. Three subgroups of normal weight, overweight and obesity were respectively divided into in both groups according to BMI. Three subgroups of increased LL, normal LL normal and decreased LL were also divided into in DTLK group.Results: The mean LCIV (mLCIV) of the DTLK group was less than control group and LCIV showed an increasing trend in DTLK group from T12-L1 to L4-L5. Different from control group, there were no significances in gender and BMI distribution of mLCIV in DTLK group (P>0.05). LCIV in increased LL subgroup was larger than that of normal LL and less LL subgroup (P<0.01). There were no relationship between TLK and BMI in both groups. BMI was positively correlated with mLCIV in control group(P=0.004). TLK and LCIV were negatively correlated (P<0.001) in DTLK group with LCIV=13.75-0.48×TLK.Conclusion: LCIV in DTLK group was less than control group with no gender- and BMI-difference. LCIV and TLK were mutually predictable in DTLK with LCIV=13.75-0.48×TLK.