Ross Hauser, MD. 

This article details many clues that can be used to identify the exact location of joint instability  through symptom analysis and physical examination. Common signs and symptoms that occur with joint instability include cracking of the joint, pain that increases with activity and decreases with rest, pain on the side of the joint, and loss of muscular power.

Making the Joint Instability Diagnosis

Common signs and symptoms that occur with joint instability include:

• cracking of the joint,
• pain that increases with activity and decreases with rest,
• pain on the side of the joint,
• and loss of muscular power.

These signs and symptoms of joint instability reflect the loss of strength or stiffness in the ligaments. In joint instability, the amount of force to produce a given range of motion for the joint is markedly reduced compared with the nonpainful, unaffected side.

Matching signs and symptoms with a physical examination is an important part of helping a patient get on the right road to healing

Static MRIs and x-rays are often misleading in a patient’s chronic pain case, especially pain due to ligamentous joint instability. (A loose joint from loose ligaments). Ignoring joint instability can have detrimental long-term consequences for the original problem joint, as well as the surrounding joints. When the cause of joint instability is properly addressed, there is a higher likelihood of resolving the joint pain problem and seeing the person return to full activity.

The key to alleviating chronic pain is locating the joint instability. Healing from pain necessitates finding the source of the pain, while knowing and understanding the correct diagnosis. Too often, the correct diagnosis of joint instability is missing.

Patients who come to Caring Medical are generally well educated on their condition. Of these patients,
about one-half know the exact location of their joint instability and its cause; the other half do not.  Even my fellow doctors do not always recognize joint instability in approximately 10% of new patients.

An MRI cannot give you this type of diagnosis; it just shows density changes in tissue. A regular stationary MRI does not show joint instability. Even motion MRIs (functional MRIs), which are taken in flexion and extension, generally do not show joint instability since it is primarily manifested by rotational or sheer stresses, not compression or flexion/extension stressors. Typical scans, such as X-rays, CT scans and MRIs, are not sensitive enough to pick up injury to the more than 900 ligaments in the body. Instead, the diagnosis of joint instability is made when the symptoms correlate with a physical examination showing it, as indicated by joint laxity or a loose end-feel to the ligament, especially when compared with the nonpainful side. Unfortunately, most clinicians, including physical therapists, massage therapists, and primary doctors, generally do not look for joint instability and lack the palpatory skills to find it.

Strong ligaments hold joint bones in place during movement and at rest

Strong ligaments hold joint bones in place during movement and at rest, while the surrounding muscles and tendons support the joint primarily during movement. If ligaments, tendons or muscles around the joint become weak, loose, or torn, they may not be able to hold the joint bones in place. As a result, a bone may partially or fully dislocate. A partial dislocation is referred to as a subluxation by osteopathic and chiropractic physicians. Subluxations occur primarily because of laxity in a ligament that connects adjacent bones. A sign of joint instability is when a patient requires frequent manipulation to properly align the bones.

Ligaments can be stretched beyond their capacity to extend or become torn by any of these 3 mechanisms; once this occurs, they are unable to return to their original length when the stretching or injurious force is removed.

Sometimes the force can be from a manipulative thrust. The bone can then sublux, since the ligament has become permanently stretched out and can no longer hold it in place. In response, surrounding muscles go into spasm and the joint swells in an attempt to protect and stabilize the joint.

3 Primary Ways That Surrounding Joint Structures Become Loose or Torn

Trauma – Generally a one-time force, such as a whiplash injury or fall on an outstretched arm.

Overuse – Can be a repetitive motion, which puts intermittent force on a body part, or creep, which is a steady load that puts a constant stretch on a ligament. An example of the latter is forward-head posturing during reading, texting, or computer work.

Multidirectional instability – A point when the joint dislocates in different directions, either to the back, side or front. Although this occurs more commonly in people who are born with very loose joints and have joint hypermobility syndrome or Ehlers-Danlos syndrome, sometimes a one-time joint trauma can be severe enough to destroy the ligament, resulting in multidirectional instability.

Adapted from Figure 22.1 in Maigne R. Diagnosis and Treatment of Pain of Vertebral Origin, 2nd ed. Boca Raton, FL: Taylor & Francis Group

Subluxation and various motions of the neck explained.

• If the patient voluntarily turns his head all the way to the left, this is an active movement and is designated by line A.
• If the examiner turns the patient’s head in rotation to the left, this is considered a passive
  movement and is designated by line P.
• When the examiner and the patient both agree that further movement is not possible, that is referred to as the “taking-up-the-slack” point (T).
• Once the taking-up-the-slack phase is completed, the examiner uses a forceful but brief thrust and exaggerates the movement, after which resistance is noted to “melt away” and a cracking sound can be heard. This brief force and very limited movement, going beyond the point of tension, constitutes what is called the manipulation or manipulative thrust (M). If this thrust goes beyond the anatomic limit (AL), a subluxation could occur.
• A subluxation typically means that a ligament has been stretched beyond its normal physiological length.
• A skilled examiner would exercise perfect control of movement and would not go beyond the AL point. If a subluxation were to occur, however, the person would be left with cervical/neck instability. Prolotherapy could resolve the instability and its associated symptoms.

To get bones back into alignment, a person may seek out chiropractic or osteopathic care. If this does not work, many people turn to self-manipulation of their own joints, thinking they will find relief. Self-manipulation hurts, not helps, people with instability.

Self-manipulation or cracking of joints with normal motions are definitive signs that joint instability
is present. Unfortunately, self-manipulation of a joint is never a good idea and always leads to
worsening of the joint instability.

The excessive rotation and force ultimately causes more ligament tearing and damage. There is a direct relationship between the amount of ligament lengthening (and damage) and the amount
of joint play or laxity. (We demonstrated this in our previously published research.) (1,2)  That is why, once a person has had a ligament sprain or joint dislocation, it is much more likely to recur

For instance, individuals with a history of ankle sprains often say they have persistent nonpainful symptoms, such as the ankle giving way during jumping and cutting activities or a feeling that it
is going to do so.

When tested, people who had ankle sprains and no symptoms (no functional insufficiencies) were shown to have impaired proprioception, altered neuromuscular control, ligament strength deficiency, diminished postural control, and an instability of the ankle complex to resist rotational forces.9-11 The ligament never regains its original stiffness, which is a measure of its ability to resist stretch. The additional length of  a stretched-out ligament (or other stabilizing structures such as the menisci or labrum) causes a permanent mechanical weakening in the tissue, which means the ligament has lost its normal stiffness. The ligament and the joint now have extra and unneeded mobility, which means they have become lax. Laxity of a joint is measured as the motions of translation and rotation at a given force or torque.(3) Clinical instability is usually present once symptoms of pain and weakness develop.

It should be noted, however, that a person can have laxity in a ligament and instability in a joint and be unaware of it. Symptoms don’t always become evident until a given force or torque (rotation/stress) is placed on the joint.

While 2 people could have the exact same joint instability (ligament laxity) and one may have a relatively sedentary lifestyle (sitting behind a desk and little exercise) and have no symptoms, the other may have a job that requires a lot of lifting and twisting and is in chronic pain. In the latter case, work places higher force and torque on the body, so the ligaments and joints need to be much stronger and tighter to function in this environment without causing pain. Understanding these
aspects of ligaments and joint instability is important because they allow someone to make sense of symptoms he or she is experiencing, and figure out whether or not clinical joint instability is the true pain-causing culprit.

The ligament’s ability to reduce stretch is its stiffness capacity. In diagnosing joint instability, a health care provider or doctor  typically examines the joint’s end-feel. This refers to the end range of joint
movement; the clinician uses end-feel to identify the nature of the resistance and the pathologic limits to the joint’s end range of passive motion.(4)  The end-feel of the painful joint (or extremity) and its range of motion is compared with the nonpainful side to determine if there is a difference. End-feel acts as a subjective measure of the elasticity of tissue and can be quantified as the mechanical property of stiffness, calculated as the change in the applied force divided by the resulting change in position length. Taking into account the signs and symptoms of ligament laxity and joint instability, as well as the findings from the physical examination, one can make the diagnosis of joint instability. MRIs and other radiological tests are often misleading.

Hip Instability for example

Consider that many acetabular (hip) labral tears are discovered on autopsy, yet those people had had no symptoms when alive.(5,6)

The acetabular labrum is only a secondary hip stabilizer; the ligaments are the primary stabilizers.(7)
Therefore, when a person does have hip instability and a labral tear is found, both the ligaments around the hip and labrum need to be treated versus only treating the labral tear.

The Site of the Instability

The source of chronic pain is not always obvious. A study investigating the sources of sacroiliac pain illustrated this point well. One hundred and twenty patients with chronic low back pain and/or sciatica were enrolled to receive injections of anesthetic and corticosteroid, either to the sacroiliac joint alone or to the joint and the ligaments.(8)

When the ligaments were injected along with the joint, the response rate nearly tripled! Ligaments are almost always involved in the source of chronic pain. Most people suffer with pain, sports injuries, or
disabilities from degenerative arthritis because they have the wrong diagnosis. The missing diagnosis is joint instability. How does a person know where the underlying joint instability is located?

A good rule of thumb is the following:

One-half of the time, the joint instability is located in the joint closest to the site and start
of maximum pain perception. If a person’s pain begins in the front of the shoulder and this is also where the point of maximum pain perception and tenderness is, then most likely the shoulder joint is the structure that is unstable.

One-quarter of the time, the joint that is unstable is the second closest joint to the site and start of maximum pain perception. This means that it is the next joint up or down in the kinetic chain from the one where the pain is located. The kinetic chain refers to all the joints and joint structures in the spine or extremities that move or handle force with a certain motion
or exercise.

See above: For the shoulder joint, the closest joints in its kinetic chain would be the elbow joint and  the upper thoracic-rib junctions (costo-vertebral joints). For instance, if a person has elbow instability, there would be excessive movement of the humerus bone, which could then put strain on the rotator cuff tendons, causing a supraspinatus tear. How the thoracic-rib junctions affect the shoulder may not seem so obvious. The muscles that attach to the scapula are stabilized or held into position by muscles that attach to the ribs (serratus anterior) and thoracic spine (rhomboids). When someone has shoulder pain, the upper back (thoracicrib junctions) area should therefore also be
examined.

• Joint instability is a combination of the closest and the second closest joint to the site 12.5% of
  the time.
• The remaining 12.5% of the time, it is the joint second farthest away from the hub in the kinetic
  chain. For the shoulder joint, that would be the neck (cervical spine) and/or wrist.

Clues to help determine the unstable joints:

What joint is the body trying to stabilize?

If a joint is becoming swollen or muscles are tightening around a joint, then that is most likely where the joint instability is located.

What motion is causing the most pain?

Nerve endings (receptors) in and around the joint and ligaments usually indicate where the person has instability.(9)

These nerve receptors typically fire when the ligaments are stretched beyond normal or at a rate that is “uncomfortable.” If a certain hip motion, such as external rotation, were to cause pain, then the instability is most likely in the anterior hip because the motion would have stretched the nerve endings of the iliofemoral ligament that stabilizes the anterior hip joint. Most of the time, the motion
that causes pain is not a compressive force. Just as the Earth does, we humans have a gravitational force going from superior to inferior down through our bodies, so the body favors compressive forces. Our intervertebral discs and articular cartilage become nourished as joint fluids are pushed into and out of these areas by gravitational compressive forces.

In other words, compressive forces on the disc and articular cartilage have an anabolic or reparative effect. This is why runners who have not been injured have healthy, strong, and thick articular cartilage.(10)

Where does the pain travel to? 

Perhaps what isn’t appreciated enough is just how many structures are affected when one single joint
becomes unstable. Consider all the structures in the hip, including 16 muscles that cross the hip joint.
Hip instability pain can refer all the way down into the big toe because of ligament laxity, or it can refer to the buttock region, inner thigh, or outer thigh because of tightness and spasm in the muscles that cross or move the hip joint.

Where is the cracking or crepitation?

People with joint instability can often hear cracking sounds or feel as if bones are hitting together when certain movements are executed. These cracking sensations are called crepitation. Experiencing crepitation when 2 structures are rubbing against each other is completely abnormal as it relates to human movements. Tendons are not supposed to rub and make sounds when going over a bony prominence, just as two bones are not supposed to be hitting each other. Long-term pain will develop if a person continues to exercise after hearing a cracking sound with that exercise. One should always exercise in the “crack-free” range of motion. There should be no cracking sensations heard or felt during exercise, as they are signs of joint instability, especially if the crepitation is associated with pain in that location.

A person may complain of pain at the base of neck, however, but feel crepitation in the mid-thoracic
region. The actual source of the instability is most likely the upper back, not the neck.

What was the initial mechanism of injury?

A common mechanism of injury is falling on an outstretched arm, which breaks the wrist. After having it casted for 6 weeks, the person complains of severe forearm pain, despite x-rays showing that
the wrist looks fine. Knowing the mechanism of injury in this case should alert someone to look for
elbow instability, because the fall on the arm would have put tremendous stress on the elbow, just as
having the wrist casted for 6 weeks would. Casting is like having the wrist temporary fused; since the
wrist can’t move, the elbow takes over to carry the load. The additional strain on the elbow is likely to
have injured the ligaments there, which is a setup for persistent elbow instability.

The wrist should be examined for instability, since a force sufficient enough to fracture the bone would surely injure the ligaments in the wrist as well. Although necessary, casting the wrist would be detrimental to ligament healing, since these tissues do not heal well when immobilized. All things considered, it is easy to see how a fracture to the wrist would also make the elbow’s stabilizing structures more prone to injury.

Sometimes pain becomes evident after an event. If the event was surgery, then knowing the type of surgery that was performed can be a clue as to where the instability is located. For instance, if
someone has a foraminotomy with a laminectomy in the lower back to correct spinal stenosis, it is quite probable that the person will have spinal instability a common complication of this type of surgery since stabilizing bony structures are removed.(11,12)

Many orthopedic surgeries worsen the instability that already exists because the procedures remove bone spurs (chondroplasty), menisci (meniscectomy),labrum (labral resection), discs (microdiscectomy),and other stabilizing structures such as bone (laminectomy, osteotomy). This just puts more stress on the surrounding ligaments and stabilizing structures after the surgery.

During joint replacement surgery, orthopedic surgeons have to sacrifice certain ligaments and stretch others. Even surgeries intended to improve stability, such as fusion operations, lead to future instability because  they put additional forces on the segments above and below the fused segment. This is called adjacent segment instability. Consequently, if a person had an adjacent segment instability fusion, any instability would most likely develop in either the L3-L4 segment or the sacroiliac joints because they are both adjacent to the L4-S1 area, which is fused and cannot move.

Spinal fusion is why adjacent segment instability and subsequent disc disease and degeneration have become so prevalent. The more active a person is after a fusion operation, the more likely it is that the segments above and below the fusion will become unstable. To make sound medical decisions, it is crucial to have an accurate diagnosis.

When the diagnosis is wrong, the treatment is also likely to be wrong. This is especially true for people with chronic pain because most are missing the correct diagnosis of joint instability. Finding the correct location of instability is the first step in resolving it.

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