Spinopelvic Alignment and Low Back Pain before and after Total Knee Arthroplasty

Abstract

Study design: Prospective cohort study.

Purpose: This study aims to examine changes in spinopelvic alignment, sagittal global balance, and low back pain (LBP) following the removal of knee flexion contracture by total knee arthroplasty (TKA).

Overview of literature: The limitation of the knee extension was correlated with the decrease in lumbar lordosis (LL). Currently, there are no studies evaluating the spinopelvic alignment and LBP before and after TKAs.

Methods: Sagittal spinopelvic alignment was evaluated in 110 subjects using radiographs of the whole spine. Parameters measured in this study included sagittal vertical axis (SVA), LL, sacral slope (SS), pelvic tilt (PT), and pelvic incidence (PI). The distribution of sagittal plane modifier grade was evaluated according to the Scoliosis Research Society-Schwab classification of adult spinal deformity (ASD). Consequently, personal history related to LBP was obtained, and the association of pre- and postoperative LBP and spinopelvic alignment was investigated.

Results: Preoperatively, 66% of all subjects showed LBP and mostly exhibited anteriorly shifted global imbalance associated with a decrease in LL and knee flexion contractures, and the subject who had severe flexion contracture of the knee joint showed more forwardly shifted global balance with backward PT and decrease in LL. After TKAs, the knee flexion contractures were eliminated in most cases, and one-third of subjects experienced decrease in LBP. However, SVA increased more and associated with slight decrease of PT and increase of SS. No significant differences were confirmed between pre- and postoperative values of LL and PI. In addition, there were no significant differences in postoperative values of spinopelvic parameters between subjects with and without relieved LBP.

Conclusions: Although one-third of subjects experienced decrease of LBP after TKAs, the sagittal global imbalance was not restored through the removal of knee flexion contracture.

Keywords: Arthroplasty; Contracture; Knee; Low back pain; Spine.

Fig. 1.

Distribution of patients according to the severity of the sagittal plane modifier grades between pre- and post-TKAs. TKA, total knee arthroplasty; PT, pelvic tilt; SVA, sagittal vertical axis; PI, pelvic incidence; LL, lumber lordosis.

Fig. 2.

Distribution of patients according to the severity of the sagittal plane modifier grades between patients with and without LBP before total knee arthroplasties. LBP, low back pain; PT, pelvic tilt; SVA, sagittal vertical axis; PI, pelvic incidence; LL, lumber lordosis.

Fig. 3.

Case example of a 60-year-old woman. (A) A preoperative radiography showing the whole spine standing lateral which exhibited the following findings: SVA, 35 mm; LL, 27°, SS, 28°, PT, 22°, PI, 50°. (B) A preoperative lateral knee radiography which indicated 32° of flexion contracture. (C) A postoperative whole spine standing lateral radiography showing more anterior-shifted global balance with the following findings: SVA, 85 mm; LL, 24°, SS, 35°; PT, 15°; PI, 50°. (D) A postoperative lateral knee radiography indicating 24° of decreased flexion contracture. SVA, sagittal vertical axis; LL, lumber lordosis; SS, sacral slope; PT, pelvic tilt; PI, pelvic incidence.