Sonoanatomic indices of lumbar facet joints in patients with facetogenic back pain in comparison to healthy subjects

Highlights

• There are anatomical changes in patients with FJD.

• Local inflammation increases distance of these joints from the skin.

• Interfacet distance decreases on either side in patients with FJD.

• Ultrasonography provides significant information in facet disease.

Abstract

Background

Nowadays, ultrasound is increasingly used with a great accuracy in performing nerve blocks for facet joint disease.

Objectives

To measure sonoanatomic characteristics for the facet joints of lumbar vertebras in patients with facetogenic pain and healthy volunteers.

Study design

Cross-sectional, observational study.

Setting

University-affiliated Specialty Clinic for Pain Management.

Patients

Twenty patients with facet joint disease (FJD) and 40 healthy volunteers (HVGs) were matched for age and sex, height, and weight. Patients with FJD were referred with complaints of pain in the left lumbar facet joints that twice responded favorably to ultrasound guided medial branch blocks.

Intervention

Medial branch blocks.

Measurement

The interfacet joint distance (IFJD) between the third, the fourth, and the fifth lumbar vertebras and their depth from the level of skin (DFS) were measured bilaterally, using a high-resolution ultrasound in both groups.

Results

Thirty-one men and 29 women with average age of 41.5 ± 9.5 years were enrolled. The IFJD for L3-L4 was 31.5 ± 4.0 mm on the left side and 31.8 ± 4.0 mm on the right side. The IFJD for L4-L5 was 31.3 ± 4.4 mm on the left side and 31.5 ± 4.0 mm on the right side. The IFJD was uniformly 2.2 mm shorter in the FJD group than those in the HVG group (P = .021). The measurements of DFS increased in lower vertebras (L3 < L4 < L5), bilaterally. With an exception of the left facet joints of L4 (P = .016), DFS measurements were similar in FJD and HVG groups.

Limitations

The diagnosis of facet joint disease was merely clinical and the total number of the patients was relatively small.

Conclusion

Interfacet distances of the lumbar vertebras are smaller in patients suffering from degenerative FJD compared with HVGs. Degenerative changes of intervertebral discs and partial reduction of space between 2 adjacent vertebras may contribute to this observation.

Introduction

Low back pain (LBP) is the most common complaints of the patients referred to a pain clinic. The LBP has multiple etiologies and according to the International Organization Pain, pain caused by lumbar facet joint is responsible for 15%-45% of all reported cases. The terminology of facet syndrome was first used in 1933 by Ghormley, which has separated this condition from the other causes of LBP [1], [2]. Among other major etiologies of lumbar pain, intervertebral disc herniation and inflammation of the sacroiliac (SI) joint can be noted [3]. Pain associated with lumbar facet joint is generally localized over the involved joint; however, it may be referred to back and thigh. Due to this latter pattern of spread, it is not uncommon for the facet joint pain to be falsely perceived as radicular pain (pseudoradiculopathy).

Diagnosis of facet joint disease (FJD) is generally made using 4 physical examination components of Revel criteria (standing flexion, returning from standing flexion, standing extension, and the extension rotation test), which describe the pain relief with rest [4]. Dependence on the lack of pain exacerbation by coughing or bending forward has yielded conflicting results [5]. Although both the computerized tomographic (CT) scanning and the magnetic resonance imaging (MRI) provide valuable information on the presence of degenerative joint disease, they lack the ability to make a final diagnosis of FJD. In another study, positron emission tomography scanning was used for diagnosis with a high sensitivity. However, low specificity (lower true-positive rates) and excessive cost of the unit have been limiting factor for its widespread use [6].

Injections of corticosteroids and local anesthetics into the joint or around the medial branch nerves have been used both for treatment and diagnosis of FJD. The use of these blocks to diagnose FJD carries significant rates of false negative due to variation in the anatomical path of the medial branch nerves and false positive due to the block of the other branches of the intervertebral nerves [7]. Performing multiple blocks while increasing its sensitivity and specificity in diagnosis of FJD is both money and time consuming. The use of ultrasound technology has lately become popular among the physicians practicing interventional pain management worldwide. In addition, the ultrasound technology has enabled us to define new sonoanatomic landmarks, which not only can be used in the success of the guided blocks as they may also be applied in diagnosis FJD in patients with LBP.

The main objective of this study was to identify sonoanatomic characteristics that are associated with FJD of the 3 lower lumbar vertebras (L3-L5). By the use of ultrasound, we measured interfacet joint distance (IFJD) as the primary end point and the distance of the facet joints from the skin (DFS) as the secondary end point in patients with established diagnosis of FJD and compared with healthy population. We hypothesized that both IFJD and DFS are decreased in patients with FJD.