Applied basic research

Studying the anatomy of the sacroiliac joints (SI joints) is a worthwhile and pioneering research undertaking. This research is gradually revealing a range of “hotspots” in the lower back. When basic research leads to direct therapeutic benefits, as is the case with the SacroLoc, then success has been achieved in both a scientific and practical sense. 

Bruno Harald Lurtz thinks carefully as he runs his index finger along the iliac crest on his spine model. The question he’s been asked is: “What role do the SI joints play in the work of an orthopedic specialist and pain therapist?” Lurtz’s finger moves down to the lower spine where the sacral and iliac bones form the articular transitions that the question refers to. He pauses for a moment and then says: “The SI joints possess a type of memory. More than anything else, they remember falls, onto the buttocks, or the tailbone, the ‘chassis’, the ‘landing flaps’ – orthopedists passionate about their work use many colorful expressions to describe the area around the buttocks, the pelvis, and the iliac and sacral bones.” These terms are easier for patients to understand. “A fall in that area, even if it happened many years ago, can continue to have extremely painful consequences,” he adds.

SI joints beginning to take shape

Massive SI joint problems account for approximately 20 percent of all the cases Lurtz deals with in his practice. Research colleagues of the pain expert based in the Köpenick district of Berlin have been conducting biomechanical and clinical-functional studies to try to gain a better understanding of such problems. Not enough was known about SI joints, despite the fact that these small joints that move via small and tiny nutations are often the source of deep-seated back pain and blockages. Scientists at the universities in Leipzig and Chemnitz decided to conduct two studies to examine the complex interrelationships in the area around the SI joints, including those involving ligaments and muscles. The researchers wanted to find out what specific effect the SacroLoc pelvic orthosis has on the SI joints. The first study alone (ref. 1; see also Bauerfeind life 2/15) made scientists sit up and take notice: “The fact that the pelvic orthosis alters the range of movement (of the SI joints) in a complex way rather than restricting it in an isolated manner marks a new discovery for the scientific community,” said the head of the study, Professor Niels Hammer. “Our data clearly shows that we need to take other parameters besides isolated compression into consideration.”

Focus on SI joint treatment

While the first study focused on the bio­mechanical aspects of the effect of the SacroLoc on local SI joint ligaments, the second study (ref. 2) mainly addressed therapeutic questions of interest to the scientists. The goal here was to determine “the medical effect of SI joint back orthoses on the clinical and functional parameters of patients with SI joint pain” – which was also the title of the study. The non-randomized prospective experimental study, which was published in PLOS ONE in 2015, was conducted on patients with SI joint syndrome and a control group of healthy patients for a period of six weeks. The study examined the effect of the orthosis on individual pain perception and muscular structures.

Use of the orthosis improves quality of life

The knowledge gained from the two studies expanded the amount of data available on SI joints, which had previously been somewhat limited. The most important finding of the second, clinical SacroLoc study was that the use of the orthosis improves quality of life. The test subjects reported experiencing less back pain and greater mobility.
Parallel measurements of muscle activity showed that applying the pelvic orthosis caused the contractions of the rectus femoris muscle to decrease in strength. The rectus femoris is considered a potential cause of SI joint problems due to the long lever arm function it exercises on the SI joints. The authors of the study suspect that excessive contraction of this muscle probably leads to SI joint pain. While no immediate change in muscle activity was detected in SI joint patients and healthy test subjects standing on one leg while wearing the pelvic orthosis, rectus femoris muscle control improved significantly in both groups when walking – which means the excessive contraction of this muscle, with its negative impact on the SI joints, was reduced as well (data in the original work).

Neuromuscular influence of mechanical compression

Studying gait parameters also showed that the pelvic orthosis has more of an influence on dynamic variables than static ones. While no immediate changes in the ground reaction forces were detected in SI joint patients or healthy test subjects standing on one leg, both cadence (number of steps per minute) and walking speed increased straight away in both groups when they put on an orthosis and began walking. The scientists concluded that these findings point to an increase in postural stability, which may manifest itself as an improvement in the unsteady gait often described in SI joint patients. The authors of the study further concluded that , as well as having a mechanical compressive effect on the pelvis, the SacroLoc exerts a neuromuscular influence on the locomotor system. More specifically, the effect of the orthosis is based on the neuromuscular connections, in which the SI joint ligaments are sensory elements and the pelvic muscles are positioning elements. Computer simulations also showed that wearing a pelvic orthosis relieves pressure on the ligament structures in the SI joints in static situations as well (data in the original work).

The second SacroLoc study investigated the influence of the orthosis on pain perception and muscle structures in healthy patients and in those with SI joint syndrome over a period of six weeks. Among other findings, the measurements showed that the SacroLoc caused an increase in both the number of steps taken per minute (cadence) and the speed of those steps. Patients also reported greater mobility in this regard.

“Studies are good, but the SacroLoc is better”

The results of the two SacroLoc studies show just how complex the process of controlling the interaction of ligaments and muscles at the SI joints actually is. Lurtz can only confirm this complexity – and the fascination this process holds for him. He repeatedly looks over the “hotspots” on his spine model. He’s also completely familiar with them in situ, as he performs more than four hundred operations in the lower lumbar spine area every year. The results of the studies support Lurtz as a practitioner. “It’s good that those two studies were conducted,” he says. “I only know of 15 or 20 studies carried out in this field – that’s all the relevant studies there are on this topic.” Lurtz has been particularly confirmed in his views about the role played by muscles as positioning elements at the SI joints: “I have often noticed that incorrectly developed pelvic muscles can threaten the entire body structure and posture.” Theories generated by a study are one thing, but practical application is another. “I don’t need to quote the studies’ findings to my patients; it’s better to just use the SacroLoc,” Lurtz explains. “After all , reducing pain and regaining mobility are the most important things for both me and my patients.”

Neuromodulatory effects are also possible

According to Lurtz, it is extremely important to ensure that symptoms do not become chronic. With the SacroLoc, which consists of a combination of elastic and inelastic knitted fabric, Lurtz is able to provide targeted support and stabilization for patients suffering from SI joint pain. The orthosis relieves the strain on the pelvis and local ligaments, and it also stimulates the trigger points of the SI joints during movement via two pads – something Lurtz believes is extremely important. Its frictional nubs are particularly effective on the insertions of the stabilizing ligaments, tendons, and muscles. This promotes circulation and eases and releases tension. Lurtz can achieve similar analgesic effects when he treats patients suffering from pain using the TENS technique (transcutaneous electrical nerve stimulation). The theory behind this technique is that electrodes applied to the skin inhibit the activity of nociceptors, which are the pain receptors in the skin. “Influencing the pain pathways in this manner, which the frictional nubs in the SacroLoc possibly do as well – this type of neuromodulation is playing a more and more significant role in pain therapy,” Lurtz explains. Muscles, ligaments, nerves – there are many different elements at play in the SI joints. 

Ref. 1: Sichting F, Rossol J, Soisson O, Klima S, Milani T , Hammer N. Pain Physician. 2014 Jan-Feb; 17(1):43-51. Pelvic belt effects on sacroiliac joint ligaments: a computational approach to understand therapeutic effects of pelvic belts.
Ref. 2: Soisson O, Lube J, Germano A, Hammer K-H, Josten C, Sichting F, Winkler D, Milani T , Hammer N. PLOS ONE10.1371/journal.pone.0116739. Published March 17, 2015. Pelvic belt effects on pelvic morphometry, muscle activity and body balance in patients with sacroiliac joint dysfunction.
[www.plosone.org].

Pictures: Bauerfeind, privat, Anika Büssemeier