Do ligaments control muscles?

Today’s article will go along with the first 2 podcasts and discusses ligaments.  The first podcast talked about the makeup of ligaments, how they get injured, what the inadequate healing process for damaged ligament is like and how to manage ligament damage.  The second podcast was on the history of Alteration of Motion Segment Integrity or AOMSI and impairment ratings.  Today’s article is Ligaments: A Source of Musculoskeletal disorders.  This was published in the Journal of Bodywork and Movement Therapies in 2009.  This article was written by Moshe Solomonow PhD MD.  We have already touched briefly on the information in this article in the other 2 podcasts, but will go into the details of what ligament damage is like for patients today.

This article starts by saying there are several ligaments in each joint and they have been considered the primary restraints of bones.  This article discusses that ligaments are sensory Organs and have significant reflexive input on activation of muscles.  The reflexive part of that statement is VERY IMPORTANT.  This shows us that ligaments are the significant controller of muscles surrounding joints and this is done without us thinking and is subconscious control of muscles.  Some joints have more muscle control for stabilization than other joints and this article shows that the intervertebral joints of the spine have an more muscular control than other joints.  So, to sum up the first paragraph of the study, ligament and muscles give stability to joints, but ligaments are sensory organs that reflexively activate or inactive muscle stability allowing muscles to participate in joint stability.    

This study shows what joints with ligament damage will be like.  The ligaments once damage will alter the muscular activity patter around a joint resulting in early onset of osteoarthritis, pain, disability and eventually the need for joint replacement surgery. 

This article showed the type of stretch or load placed on ligaments is significant.  A slow rate of stretch on a ligament will cause little tension of the ligament, but a fast stretch or load on ligaments will create a high load often leading to ligament damage or rupture.  They showed that a fast stretch on a ligament even if within the normal range of motion for the ligament, will lead to rupture.  This correlates well with most personal injury patients. 

Most personal injury patients have fast stretching of ligaments in MVC or slip and falls.  Not that the ligaments couldn’t withstand the length of stretching, but can not do it at the fast speed of most injuries.   I have heard this type of ligament damage compared to silly putty.  If you have some silly putty and stretch it out nice and slow you can stretch the silly putty a long way without breaking it.  If you take the same silly putty and pull it apart really fast it will tear almost instantly not allowing for any stretch. 

This article talked about cyclic loading of ligaments, or moving ligaments below the threshold to tear them, but doing it repetitively.  This constant repetitive loading of ligaments showed the body needed a 24-48 hour period for recovery.  This has been helpful with work place injuries where repetitive loading of joints takes place with long hours and not enough time between shifts to allow the ligaments to recover.  In contrast, this study showed that moderate exercise or repetitive occupational activities with sufficient rest and recovery allows ligaments to have an increase in overall strength over time.  This study also showed that immobilization or decreased physical activity results in weaker and thinner ligaments with an increased potential for injury.  This information is helpful with patient’s that are very active vs. patient that are not active.  Ligament damage is more likely in less active patients.  I see this a lot in the elderly population.  In general, the elderly population is less active and this will lead to weaker and thinner ligaments and will increase the potential for injury in this population. 

Now for my favorite part of this article:  This section of the article is titled ligaments as sensory organs.  This part of the article talks about the ligament-muscular reflex.  This section discusses how ligaments are reflexively (or subconsciously) involved in muscle control.  The conclusion of the article says “It is evident that ligaments evolved to become the optimal biological passive tissue to provide the function of joint stability.  Ligaments when stretched reflexively communicate with muscles to active the muscles to support the joint.  When ligaments are no longer being stretched in a low load situation, they will reflexively inhibit muscle activation around the joint allowing for muscle relaxation.  This article refers to ligament damage as a neuromuscular disorder.  Neuromuscular disorder means a disorder of nerves controlling muscles.  The neuro in this case is the reflexive neurological control of ligaments.  This reflexive control ligaments have over muscles will be decreased or lost with ligament damage or rupture and will not be restored.    

To help illustrate what this type of ligament control I want to use an example from the 2021 NFL season Superbowl.  The Los Angeles Rams played the Cincinnati Bengals.   Odell Beckham Jr. was brought in to help the Rams win the playoffs and Superbowl.  Lets talk about Odell Beckham jr.’s knee.  He grew up learning to walk and run with healthy knees.  As he learned to run his ligaments surrounding the knee would be stretched and would reflexively signal the muscles surrounding his knee to help with stabilization and the ability to run safely.  He didn’t have to think about how to run and what muscles needed to be involved in running it was reflexive thanks to the ligaments.  As fate would have it Odell Beckham Jr. was playing the Cincinnati Bengals Oct 25^th 2020 and had a grade 3 ACL tear.  A grade 3 tear is complete tearing of the ligament.  This ligament was surgically reconstructed.  Now back to the Superbowl Winter 2022.  Odell Beckham jr. was having a reasonably good game.  He went out for a short pass and was wide open.  No one even touched him, but down he went in a lot of pain.  Once again, he had a complete or grade 3 ACL tear.  What happened?  For Odell Beckham jr’s entire life when he ran, he did this with subconscious reflexive ligament control of the muscles. 

Once the ACL was torn in 2020 he lost the subconscious reflexive ligament control of muscles.  Now when he runs his body has to learn how to protect the joint without ligament reflexive control.  The body is amazing and can adapt, and he was able to run, but never the same.  Without the normal joint function, he lost the ability to stabilize the joint and without even being touched tore the ligament again.     

After ligaments are damage the ligament loses its ability to reflexively control muscles.  This in 2 sided.  Like Odell beckam Jr.’s example the body will not be able to activate muscles to help stabilize a joint with activity, and when the body is in a low activation the ligaments will no longer be able to reflexively signal the muscles to relax.  This study showed that this often leads to muscle spasms.

In conclusion the study showed there are 2 classes of disorders with ligament damage the mechanical and neuromuscular.  The mechanical problems seen with ligament damage includes joint laxity, instability, osteoarthritis and rupture of ligaments.  The reflexive control of ligaments once lost leads to complex motor disorders with changes in proprioception (or the bodies ability to perceive the location and movement), kinesthetic perception (or the bodies ability to correctly move), muscle activation loss, loss of joint stability and decrease in overall function. 

Real world experience

I have seen this example a few times and think it fits in well with this article.  A patient is in a MVC and comes in for the initial examination.  Among other tests an AROM testing is done with dual inclinometers.  The patient has a significant decrease in cervical spine AROM.  During the course of care x-rays are done and a diagnosis of alteration of motion segment integrity or AOMSI is made.  Following care, a re-evaluation is done, prior to my final report and impairment rating.  During the final exam cervical AROM is done again.  This patient again has a significant decrease in cervical AROM.  Months later I am brought in to a deposition for this patient.  The defense attorney always asks the following questions.  Dr. Clayton you have diagnosed the patient with catastrophic ligament damage or what you have called AOMSI is that correct?  Of course, I answer this is correct.  Then they ask did you perform AROM testing of the patient’s cervical spine on your last evaluation?  Again, I answer yes.  Then they ask the next question convinced they have me in their trap.  Dr. Clayton how can the patient have ligament damage and a decrease in range of motion?  They are under the impression that ligament damage would cause joint laxity.  This is why I hate the term ligament laxity when associated with AOMSI.  As seen in this podcast and the last podcast AOMSI is not ligament laxity.  It is complete tearing of ligaments at a motion segment.  As seen in today’s article once ligaments are torn, they lose the ability to reflexively control muscles for joint stability.  The ligaments will no longer be able to recruit muscles when needed and will no longer be able to tell muscles when to relax.  As seen in this article ligament damage often leads to muscles spasms.    The patient comes into my office and we do an AROM test of the cervical spine, but the ligaments are unable to reflexively relax the muscles surrounding the cervical spine allowing for full AROM.  Similarly, when the patient lays down at night the ligaments can no longer recognize a low load situation and send a signal to the muscles to relax.  The patient can lay in bed all night with muscles spasms.  This has thrown a couple attorneys off in deposition and helps with the understanding of what ligament damage really means to patients.