Levator Avulsion: Simply Explained
In 2007, quite a few years ago now, I had an ‘Oh My God’ moment in a lecture at one of our National Conferences. Professor Peter Dietz, a Sydney Urogynaecologist, was revealing to the attentive audience of doctors, physiotherapists and nurses that, what had been always attributed to nerve damage in the pelvic floor muscles, was in fact sometimes due to a concept called Levator Avulsion– where part or all of the pelvic floor muscles were pulled off the pubic bone on one or both sides. Peter used 3D/4 D ultrasound to confirm his findings and similarly Professor John DeLancey, a world-renowned anatomist and urogynaecologist from the USA, discovered the same concept through MRI technology.
In fact, this had first been mentioned in 1907 by Halban and Tandler and again in 1943 by Howard Gainey, a general obstetrician from Kansas City, but was seemingly ignored by the medical fraternity until 2005. (Prof Hans Peter Dietz)
The levator ani muscles (particularly pubo-rectalis) forms the levator hiatus and is of central importance in pelvic organ support and the maintenance of urinary and faecal continence. Avulsion injuries– are a disconnection of the muscle from its insertion on the inferior pubic ramus and the pelvic side wall associated with vaginal delivery.(1) Avulsion of the levator ani muscle from the pubic bone is known to occur in up to 36% of parous women.
The levator hiatus represents the largest hernial portal in the human body- what this means is if the muscles have pulled off the pubic bones, the gap is wider and there is a clear opportunity for the internal organs to relax or prolapse down with increases in intra-abdominal pressure such as with coughing, lifting, bending, squatting etc.
An analogy to make it easier to understand is if half of your deltoid muscle (shoulder) was cut through then it would be pretty hard to lift your arm if that muscle is not attached across the joint. But whilst that helps you understand why the muscles don’t work, the process of damage is much more like a rope that is gradually fraying, as the mountain climber gets closer to the top of the mountain because it is slung over a sharp rock- one fibre pings, then a few more and for some birth injuries, the rope completely gives way (the fibres completely avulse).
Now women are pretty shocked when they hear that they have avulsed their muscles off the pubic bone because it sounds pretty final- but often there is a moment of clarity as well-because the good devoted exercisers have been furiously working away at their pelvic floor exercises and are frustrated when there is no improvement in strength. So understanding about the process is very useful.
What to do about this?
I find if there is a partial avulsion it helps for patients to visualize the deficient right/left side on my model of the pelvis and I get them to take a photo of this model with their phone and view the muscles they are trying to recruit as they do the exercises. That allows them to use the brain to help recruit every fibre.
Then once they know there has been significant, and for now, permanent damage of their pelvic floor muscles what is paramount is early prevention of prolapse. This involves the things we have talked about continually on this blog:
- pelvic floor muscle training (for those muscles still attached),
- bracing with increased intra-abdominal pressure (especially bending),
- correct positioning and coordination for defaecation and particularly pelvic floor-friendlyexercising– avoiding those manoeuvres which will push pelvic organs down that hernia portal!
- early use of a pessary- a silicone device to help support the internal structures to prevent future prolapse
So in summary from Peter’s website: All we can say right now is that pelvic floor muscle trauma (‘avulsion’)
weakens the muscle by about 1/3 on average
makes the muscle more stretchy by about 50%
enlarges the opening of the pelvic floor (the ‘hiatus’) by about 1/4
more than doubles the risk of bladder prolapse
triples the risk of prolapse of the uterus (the womb).
triples the risk of a prolapse returning after pelvic floor surgery
The next Oh Yes moment will be when stem cell research has perfected the implantation of stem cells which will help re-grow the muscles. Did I ever tell you that I scoffed loudly when the movie Face Off was released…….