Correlation Between Coronal Position Sequence of Lumbar and WOMAC Score in Knee Osteoarthritis (KOA) in Standard Standing Position

Abstract

Introduction

Sagittal sequences of the spine have been shown to correlate with knee osteoarthritis (KOA), but coronal sequences and KOA have never been studied before. The study required patients to use a standard standing posture and aimed to explore the relationship between coronal position of lumbar spine and WOMAC score in KOA.

Methods

This is a cross-sectional observational study. Data on a total of 268 patients with KOA were collected. Patients were photographed in a standard standing position and lumbar–sacrum offset distance (L-SOD) and lumbar–knee offset distance (ΔL-KOD) were calculated. Patients were then divided into different groups according to different critical values and differences were compared.

Results

In the L-SOD of L1–3, WOMAC function (P = 0.021, P = 0.032, P = 0.001) and total score (P = 0.039, P = 0.034, P < 0.001) were different. In the L-SOD of L3–4, WOMAC pain score were different (P = 0.001, P = 0.032). At a cutoff of 13 mm, ΔL-KOD of L1–2 showed significant differences in pain part (P = 0.025, P = 0.039) and total score (P = 0.036, P = 0.050). There were significant differences in pain (P = 0.023, P = 0.027, P = 0.022), function (P = 0.048, P = 0.038, P = 0.047), and total score (P = 0.030, P = 0.027, P = 0.029) of L3–5. In the 18-mm cutoff group, only L1 and L2 have differences in the pain part (P = 0.050, P = 0.038).

Conclusion

Coronal balance of the lumbar spine is associated with knee pain and function. The pelvis plays an important role in maintaining the coronal balance. Both the lumbar spine and the knee joint should be considered when develo** the surgical strategy.

Plain Language Summary

As a result of population aging, the number of patients suffering from both knee osteoarthritis (KOA) and degenerative diseases of the lumbar spine is increasing. It has been reported that patients with KOA have less symptomatic recovery after lumbar surgery, and that patients with lumbar degenerative disease have less symptomatic improvement after knee surgery than those without lumbar disease. So the knee and lumbar must be interacting in some way. Previous studies have confirmed the correlation between lumbar sagittal position sequence and KOA. However, no studies have been conducted on coronal sequences and KOA of the lumbar spine. We believe that it is because patients are required to stand naturally when taking coronal x-rays, and natural standing will lead to individual differences in the distance between the feet of patients, thereby preventing analysis. In our study, for the first time, we used a uniform stance to avoid this effect. The advantage of uniform stance is that individual differences can be excluded, and the same patient can be compared before and after treatment (because the natural stance of the patient’s feet will be different before and after treatment), which is greatly conducive to the study. Our research found that the offset of the lumbar spine in the coronal position and the distance between the central vertical line of the lumbar spine and the bilateral knee joint are significantly correlated with knee pain and function. This may have some guiding significance for lumbar and knee surgery. For lumbar surgery (such as degenerative scoliosis), previous studies have suggested that short segment fixation is sufficient for patients with small Cobb angle. However, according to our conclusion, this may cause accelerated knee joint degeneration in the patient’s later stages, which requires the surgeon to comprehensively evaluate the condition of the patient’s knee and lumbar spine, and then formulate surgical strategies. The same is true for knee surgery: previous studies have shown no significant correlation between knee deformity and pain. Therefore, for patients with knee deformity and accompanying pain, knee surgery may not be the best choice, and it is more important to correct the deviation of the spine.