Paper of the month May 2023

Sacroiliac joint pain increases repositioning error during active straight leg‑raising
Eur Spine J. 2023 Apr 12. doi: 10.1007/s00586-023-07556-0. Epub ahead of print. PMID: 37043054.
Morito T. and Kaneoka K.

Dr. Morito and Prof. Kaneoka aimed to evaluate the repositioning error of patients with unilateral SIJ pain using an active straight leg-raising repositioning test (ASLR-Rt). I respect them because they attempted to evaluate the SIJ function itself.

Pain intensity is mainly used to evaluate sacroiliac joint (SIJ) dysfunction, and SIJ injection efficacy for diagnosis is determined by the pain relief rate, with various cutoff values ranging from 50% to 90%. However, pain is a subjective evaluation. In SIJ care, objective indices are required as much as possible. We ask how long a patient can remain seated on a chair to assess the severity of SIJ dysfunction in a simplified manner. We consider a patient to be quite severe if the sitting tolerance is less than 15 minutes. An increase in the sitting tolerance time indicates that the treatment has been effective. At a recent webinar, Dr. Jan-Paul Wingerden mentioned in his lecture about one-legged standing and active straight leg raising test (ASLRT) to examine part of the SIJ function. During the meeting, Dr. Bengt Sturesson commented that he uses the ability to apply load after an SIJ injection as a criterion. We thought that was a good method and immediately adopted it in our clinical practice. We would like to recover the function of the SIJ. So we would like to have a lot of objective indicators to judge the severity and the effectiveness of the treatment.

In this paper, participants were passively raised their lower extremity at 45° by an examiner. The participants held the lower limb in a raised position and memorized the position of the lower limb. The ASLR was performed three times, targeting the base angle. Repositioning error was calculated as the difference between the base angle and the participant’s attempt to adjust the target angle. In this paper, authors hypothesize that in patients with SIJ pain, proprioception is also impaired and that the ASLR angles do not go to the same angle. The authors investigated whether the repositioning error is significantly greater in patients with SIJ pain than in in patients with low back pain and in healthy control. The results showed that patients with SIJ pain demonstrated an increased reposition error during ASLR-Rt compared to patients in the low back pain and healthy control groups. Furthermore, patients with SIJ pain demonstrated an increased reposition error on the symptomatic side compared to the asymptomatic side.

ASLRT angle 45 degree is so nice. Authors stated the reason why they set the angle to evaluate SIJ function as below. Instability and pain were evaluated when the lower extremity was raised 20 cm above the floor. In the initial stage of leg-raising, the moment to the lower limb is large, and the muscle activity of the rectus femoris and other muscles is also large. However, high muscle activity is not required for assessing proprioception. In many cases, ASLR cannot be performed when the ASLR angle exceeds 60°, owing to the influence of muscle flexibility. From the viewpoint of muscle activity and flexibility, 45° is considered appropriate for evaluating proprioception.

I felt it was very interesting that authors stated that improvement in repositioning error might be used to determine treatment efficacy. And, one possible treatment would be to practice ASLR with the goal of a set angle and provide feedback if the repositioning error is large, which would be one effective exercise to improve motor control in patients with SIJP.

Would the ASLRT-Rt results be different if the pelvis was manually compressed, if a pelvic belt was tightened, or if an SIJ injection was used to relieve pain? Such an evaluation might have provided more insight into sacroiliac joint function. If the ASLRT-Rt error is reduced when both the pelvic belt is tightened and the transversus abdominis is contracted under ultrasound, it may be possible to say from a functional standpoint that transversus abdominis training could replace pelvic belt training. The degree of ASLRT-Rt repositioning error may also vary with age and gender. Potential hip disease (acetabular dysplasia) may also be a factor.

Nevertheless, this is an ambitious and excellent study. I would like to ask the authors what their intentions were in designing this study. Also, does this apply to SIJ in athletes that the authors see frequently? Or do athletes with SIJ pain have as few repositioning errors as the healthy control?

  • I would like to hear what Dr. Jan-Paul Wingerden and other physical therapists think about this paper.
  • What is Dr Sturesson's opinion?
  • Dr. Kools used the ASLRT angle to determine the severity of SIJ dysfunction. I would like to hear his opinion as well.

Daisuke Kurosawa


Leave a Comment

Comment by Tsuyoshi Morito |

Thank you very much, Dr. Kurosawa.
I am the author, Tsuyoshi Morito. I am glad you are interested in this paper.

The ASLR-Rt is a true serendipity in clinical practice.
One day, I was in clinical practice with the author, Dr. Kanaoka.
An athlete with sacroiliac joint disorder said, "I don't know where my lower limbs are."
Dr. Kaneoka thought it was unlikely and asked him to lift, memorize, and reposition his lower extremity.
The lower limb was in a completely different position. We then tried it in various cases and decided to try it in this study.

Although 30° and 60° were candidates as the setting angle of the lower limb for this method, we chose 45° for the following reasons.
The current method of ASLR test evaluates pain induction and instability by raising the lower limb to a height of approximately 20 cm above the bed. For a person of 170 cm height, the angle is calculated to be approximately 15-20°. Setting a smaller angle was considered to induce higher muscle activity and pain.

In addition, many studies have used 70° as a positive evaluation criterion for tight hamstrings, and 60° may not be achievable due to the tightness of the hamstrings.
In addition, if an element of muscle stretch is included, it will provide a hint to the muscle spindles and make repositioning easier.
For these reasons, we set the angle at 45°.
However, I now think that it would have been better to measure the SLR angle of each subject and use the middle value as the reference angle.

In clinical practice, we sometimes set the reference angle at various angles, not limited to 45°, and ask the subject to reposition. I would like to develop this method in the future. Thank you.

Comment by Daisuke Kurosawa |

It is a great luxury to have the author directly explain his own paper.
I felt the motivation for the research was very clinical and fine!

Please add 6 and 2.