Paper of the month November 2023

Posterior intra-articular fixation stabilizes both primary and secondary sacroiliac joints: a cadaveric study and comparison to lateral trans-articular fixation literature.

Sayed D, Amirdelfan K, Hunter C, Raji OR. J Orthop Surg Res. 2023 Jun 3;18(1):406.

Correspondence of this paper is Mr. Oluwatodimu Richard Raji. I met him at 11th Interdisciplinary World Congress on Low Back & Pelvic Girdle Pain in Melbourne this November. He is principal engineer of Medical Device Development company. I knew that he had already various biomechanics research on the SIJ. I am interested in his researches on the difference of SIJ motion between man and woman by using many cadavers.

In this paper, he reported that posterior SIJ fixation technique using LinQ SI joint Stabilizaion System; PainREQ was equivalent to the lateral approach e.g. iFUSE implant system, while producing superior stabilization during lateral bend and axial rotation.

The methodology of the study follows the paper below.

Lindsey DP, Parrish R, Gundanna M, Leasure J, Yerby SA, Kondrashov D. Biomechanics of unilateral and bilateral sacroiliac joint stabilization: laboratory investigation. J Neurosurg Spine. 2018 Mar;28(3):326-332.

A comparison is made with the lateral approach. The subjects of this paper were six fresh-frozen cadaveric sacroiliac joints (four females and two males), 34 to 37 years of age, which is a relatively young age group of cadavers. On the other hand, the study by Lindsey et al. included eight cadaveric specimens (age range 28-57 years, 6 females and 2 males), 4 of which were in their 50s, indicating a relatively older age range.

Dr. Volker Fuchs noted in Figure 9 that the posterior has a smaller standard deviation of sacroiliac joint control than the lateral. In other words, the effect is stable. This may be due to the fact that in the lateral approach, the tip of the implant is embedded in the sacrum, so fixation depends on the quality of the sacrum.

I do not agree with the idea of distracting one sacroiliac joint for fixation and applying compression to the other side as shown in Figure 10. I do not feel that this posterior approach is superior to the DIANA approach as the approach was almost the same and a smaller implant was placed in the same location.

However, in Melbourne I was able to hear directly from him that it is important to place the implant at the S2 level, which is more distal than DIANA. Page 7 of 12, in the discussion section, a comparison with DIANA is mentioned.

I would like to hear the opinion of expert SIJ surgeons. I would appreciate any comments from a scientific point of view.

I have had discussions with Mr. Richard Raji via email also regarding sacroiliac joints. I have given my best and he has responded with sincerity. I believe in his pride as an engineer. I am sure he will continue to inspire SIMEG in many ways.

Daisuke Kurosawa

• Comments from Dr. Volker Fuchs on 19 November, 2023

I think the paper is quite straight forward and good to understand.

But in my opinion the conclusions drawn by the author regarding the DIANA/NADIA method are not correct. The DIANA/NADIA implant is exactly at the same place as the LinQ implant, namely at the second sacral vertebra a little below the disc space of S1/S2. I also do not share the author's opinion that the distraction of one joint leads to stabilization of the contralateral joint through compression. In my opinion, increasing the pretension of the entire pelvic ring via the strong anterior iliosacral ligaments and the very tight dorsal fascia at the level of the lumbosacral junction plays the decisive role of stabilizing also the contralateral SIJ using the dorsal approach.