The use of fluoroscopically-guided diagnostic injections is currently regarded as the most reliable means of identifying symptomatic lumbar discs, lumbar facet joints and sacroiliac joints. Each of these structures can be hydraulically distended to provoke a concordant (familiar) pain response when symptomatic. Subsequent introduction of an anesthetic with substantial pain relief fulfills the criteria for identifying a symptomatic structure by diagnostic injection.

Identifying symptomatic structures by physical examination is not so clear cut. The centralization phenomenon has been shown to be predictive of discogenic pain¹. The source of pain which only peripheralizes during dynamic mechanical testing can be discogenic¹, but cannot always be readily determined. Some examples of pathologies present in patients whose pain only peripheralized during testing includes a gas filled disc, a swollen dorsal root ganglion and an avulsion ridge of the vertebral end plate¹¹.

It has been found that use of the McKenzie lumbar examination augmented by specific sacroiliac joint (SIJ) pain provocation tests⁴ can reliably predict painful sacroiliac joints¹². It was also noted in this study that it can be difficult to discern between pain stemming from facet joints and sacroiliac joints as positive SIJ pain provocation tests can be elicited in the presence of symptomatic lumbar pathology.

The use of pain patterns and lumbar pain provocation tests have not been found to be helpful in identifying painful lumbar facet joints^2,3,5,6,8,9. Only one study has found common characteristics to be noted during the physical examination of patients who had positive single diagnostic injections of lumbar facet joints⁷. These characteristics include:

1. Age over 65 years

2. Pain well relieved by recumbent position

3. Absence of pain exacerbation by coughing

4. Pain not worsened by forward flexion

5. Pain not worsened when rising from flexion

6. Pain not worsened by hyperextension

7. Pain not worsened by extension-rotation

Presence of five or more of these characteristics (including pain relief by lying) identified most of those patients who had positive responses to single diagnostic facet blocks, with a positive predictive value of 92% and a negative predictive value of 80%. However, there are limitations to this study. Single diagnostic blocks of lumbar facet joints have a false positive rate of 32%¹⁰, so the actual sensitivity of these characteristics may be lower. Another limiting factor to this study is that it is unclear what is meant by Anot worsened.@ The phrases Anot worsened@ and not Aexacerbated@ are used interchangeably in the paper. It is not clear if they mean that any increase in pain during the activity does not persist afterward, or if they mean that the pain is Anot provoked@ or Anot increased@ by the movements listed. This uncertainty makes it difficult to apply these criteria in the physical examination. In their paper, Revel and colleagues concluded that these characteristics may be helpful in selecting which patients should receive facet blocks, but they cautioned against their use as diagnostic criteria for individual patients with symptomatic facet joints due to the high false positive rate of single facet injections.

However, the characteristics identified by Revel, et al may be incorporated into the McKenzie dynamic mechanical assessment if it is assumed that Anot worsened@ means that any increase in pain does not persist. Would their inclusion help identify facet joints as pain generators? The following cases give examples of the mechanical assessments for patients with painful facet joints for each level of the lumbar spine. These patients all had chronic low back pain and underwent a blinded physical examination prior to undergoing diagnostic blocks. The results of Revel=s study were not known at the time of the examination; therefore, the results of rising from flexion and extension-rotation were not specifically noted in each case.

Movement loss: major loss of extension, minimal loss of right side gliding.

Test movements: Prior to testing: right lumbogluteal pain.

This case, in which the pain originated from the upper lumbar spine, clearly demonstrates the difficulty in identifying the pain generator by physical examination. The patient had no symptoms in the upper lumbar spine, had pain provocation from the lower lumbar spine and had five positive sacroiliac provocation tests. Revel=s characteristics are not met as the patient was under 65 years of age, had worsening of her pain with both flexion and extension, and was not better in lying. There was no centralization of pain or obstruction to movement following repeated movement testing, so only discogenic pain is ruled out with certainty.

Posture: right lateral shift, not relevant

Test movements: Prior to testing: Pain across L4/5, left lateral thigh and leg paresthesias

Extension-rotation increased back pain, not worsened

SIJ tests: all negative

Other: positive spring test at L4 only

Revel=s criteria would be met in this case. The pain is better in lying, not exacerbated by coughing, and not worsened by flexion, extension or extension-rotation. There is no peripheralization of pain with repeated sagittal plane movements. There is no centralization of pain with repeated movement testing, ruling out the disc as the pain generator. The lateral shift is not relevant as the patient was able to reverse the curve by sidegliding across midline. There is no suggestion of sacroiliac joint involvement.

SIJ tests: positive for left Gaenslen=s, compression and sacral thrust

Hip exam: painful resisted left hip flexion and passive hip abduction

This case does not meet Revel=s criteria as the patient is under age 65 years, has worsening of pain with extension and exacerbation of pain with coughing. The SIJ pain provocation tests are all false positives. Presence of symptoms above the level of L5 helps to identify that the sacroiliac joint is not involved. There is no evidence of disc involvement based on pain behavior or movement loss with mechanical testing. The two positive tests in the hip examination are not helpful in explaining why the patient has constant low back pain. The presence of illness behavior helps to confound the situation, but it is important to note that there is an underlying pathology as determined by diagnostic injection. The mechanical assessment in this case can only be that the patient has a mechanically indeterminate source of lumbar pain.

Test movements: Prior to testing: right lumbogluteal pain

RFIS no effect

EIS no change in movement loss following RFIS

REIL increased pain at end range, not worsened

SIJ tests: positive for compression, (R) Gaenslen=s, Patrick=s test was also positive.

Other: positive Spring test at L5 only

Revel=s criteria are met in this case. The patient was better lying, had no pain exacerbation by coughing, and was not worsened by flexion, rising from flexion or extension. The sacroiliac joint can be ruled out as a pain generator as there are only two positive provocation tests. Patrick’s (FABERE’s) test is not a sensitive test for sacroiliac joint pathology.¹¹ The lack of centralization of pain and lack of obstruction to movement with mechanical testing excludes the disc as a pain generator.

Movement loss: major loss of extension

Test movements: Prior to testing: right PSIS area pain

RFIL not tested

Extension with left rotation NE

SIJ tests: positive for compression only

Hip exam: negative

Diagnostic studies: Previous lumbar MRI and myelogram/CT. Negative right SIJ injection, negative discogram at L5/S1. Double diagnostic injections confirmed the right L5/S1 facet as the pain generator.

Case #5 meets Revel=s criteria. This patient is the easiest to sort out of the five cases given. There is no peripheralization of symptoms and no evidence of pain stemming from lumbar discs, the sacroiliac joint or the hip.

Three of the five cases presented had double (confirmatory) blocks, which rules out false positive responses for the diagnostic facet injections. The remaining two have had negative diagnostic injections of adjacent structures, minimizing the likelihood of false positive facet injections. At least five out of seven of Revel=s characteristics are present in three of the cases presented, which would have correctly predicted the positive response to facet joint injection. The two cases in which less than five of the characteristics were noted were at the levels of L1/2,2/3 and L3/4. Revel=s study included only the lower lumbar levels, so it is possible that the characteristics which were identified may not apply to the upper lumbar spine. This would limit their diagnostic utility. It appears that Revel and colleagues may be justified in cautioning against using their facet joint characteristics for diagnostic purposes.

There are a number of factors which confound the mechanical assessment of patients who have painful facet joints. Employing data collected from a larger group of patients who had positive diagnostic injections to establish the pain generator, the following factors were noted which can confuse the examiner:

2. The upper lumbar facet joints can refer to the leg.

1. Positive Spring tests to the spinous processes may be present, which suggests discogenic pain rather than painful facets. When present in patients with painful facet joints, they are not necessarily indicative of the level of involvement.

What, then, are common characteristics of the dynamic mechanical lumbar assessment that may suggest symptomatic facet joints? The following list has been developed:

1. The pain is usually worse with static positions (flexion or extension).

While this list is not definitive, it is a start toward identifying when the facet joint is the pain

generator. Additional research is needed to assess the ability of a dynamic mechanical evaluation to predict the presence of symptomatic facet joints. Until then, these patients remain mechanically indeterminate.

1. Donelson R, Aprill C, Medcalf R, Grant W. A prospective study of centralization of lumbar and referred pain. Spine 1997; 22: 1115-1122.

2. Helbig T, Lee CK. The lumbar facet syndrome. Spine 1988; 13: 61-64.

5. McCall IW, Park, WM, O=Brien, JP. Induced pain referral from posterior lumbar elements in normal subjects. Spine 1979; 4: 441-446.

6. Revel M, Listrat VM, Chevalier X, et al. Facet joint block for low back pain: identifying predictors of a good response. Arch Phys Med Rehab 1992; 73: 824-828.

7. Revel M, Poiraudeau MD, Auleley GR, et al. Capacity of the clinical picture to characterize low back pain relieved by facet joint anesthesia. Spine 1998; 18:1972-1977.

8. Schwarzer AC, Aprill CN, Derby R, et al. The relative contributions of the disc and zygapophyseal joint in chronic low back pain. Spine 1994; 19:801-806.

9. Schwarzer AC, Aprill CN, Derby R, et al. Clinical features of patients with pain stemming from the lumbar zygapophyseal joints. Is the lumbar facet syndrome a clinical entity? Spine 1994b; 19: 1132-1137.

10. Schwarzer AC, Aprill CN, Derby R, et al. The false-positive rate of uncontrolled diagnostic blocks of the lumbar zygapophyseal joints. Pain 1994c; 58: 195-200.

11. Young, S. Unpublished data.

12. Young S, Laslett M, Aprill C, Kelly C. The sacroiliac joint: a study comparing diagnosis by physical examination and contrast enhanced diagnostic block arthrography. Presented at the North American McKenzie Conference, New Orleans, 1998.