According to the National Institute of Health’s, National Institute of Arthritis and Musculoskeletal and Skin Disorders:
A sprain is an injury to a ligament (tissue that connects two or more bones at a joint). In a sprain, one or more ligaments is stretched or torn. A strain is an injury to a muscle or a tendon (tissue that connects muscle to bone). In a strain, a muscle or tendon is stretched or torn.
Historically, doctors of all disciplines in the clinical setting and lawyers in the medical-legal arena have erroneously attempted to separate them into 2 distinct injuries allowing a false conclusion to be derived in either prognosis or legal arguments when considering connective tissue pathology as sequella to trauma.
Anatomy of Sprains and Strains
Solomonow (2009) wrote:
There are several ligaments in every joint in the human skeleton and they are considered as the primary restraints of the bones constituting the joint. Ligaments are also sensory organs and have significant input to sensation and reflexive/synergistic activation of muscles. The muscles associated with any given joint, therefore, also have a significant role as restraints. In some joints, such as the intervertebral joints of the spine, the role of the muscles as restraints is amplified. The role of ligaments as joint restraints is rather complex when considering the multitude of physical activities performed by individuals in routine daily functions, work and sports, the complexity of the anatomy of the different joints and the wide range of magnitude and velocity of the external loads. As joints go through their range of motion, with or without external load, the ligaments ensure that the bones associated with the joint travel in their prescribed anatomical tracks, keep full and even contact pressure of the articular surfaces, prevent separation of the bones from each other by increasing their tension, as may be necessary, and ensuring stable motion. Joint stability, therefore, is the general role of ligaments without which the joint may subluxate, cause damage to the capsule, cartilage, tendons, nearby nerves and blood vessels, discs (if considering spinal joints) and to the ligaments themselves. Such injury may debilitate the individual by preventing or limiting his/her use of the joint and the loss of function. Pgs. 136-137
While ligaments are primarily known as mechanical or supportive structures responsible for joint stability, they have equally important neurological functions. Anatomical studies have shown that ligaments in the extremities and the spine are endowed with nerves called mechanoreceptors. The presence of such that sense and send neurological information to the spine and brain in the ligaments confirms that they contribute to proprioception (feeling and analyzes one’s physical positon in space and time) and kinesthesia (similar to proprioception but can maintain feeling in these nerves even with aberrant neurological imput elsewhere) and also has a distinct role in reflex activation or inhibition of muscular activities.
Simply put, the nerves in ligaments attempts to alter muscle activity to prevent further biomechanical failure and pathology (bodily injury), which effects one’s ability to move in a balanced homeostatic manner leading to further functional loss in a short amount of time. The presence of such nerves in the ligaments confirms that they contribute to proprioception and kinesthesia and have a distinct role in reflex activation or inhibition of muscular activities. Therefore, the muscles and tendons (which are inherent in muscular activity), are responsive and dependent upon ligament activity in function with both normal and pathological (inclusive of trauma) activities.
Solomonow (2009) also reported that as far back as the turn of the last century, that a reflex may exist from sensory receptors in the ligaments to muscles that may directly or indirectly modify the load imposed on the ligament. A clear demonstration of a reflex activation of muscles finally provided in 1987 and reconfirmed several times since then. It was further shown that such a ligamento-muscular reflex exists in most extremity joints and in the spine.
Mechanism of Injury
A Single trauma according to Panjabi (2006) can cause either a tear in the ligament called laxity or a subfailure injury of the spinal ligaments and injury to the mechanoreceptors embedded in the ligaments and the following cascade of events occur: pgs. 669-670
NOTE: The subfailure injury of the spinal ligament is defined as an injury caused by stretching of the tissue beyond its physiological limit, but less than its failure point.
- When the injured spine performs a task or it is challenged by an external load, the transducer signals generated by the mechanoreceptors are corrupted.
- Neuromuscular control unit has difficulty in interpreting the corrupted transducer signals because there is spatial and temporal mismatch between the normally expected and the corrupted signals received.
- The muscle response pattern generated by the neuromuscular control unit is corrupted, affecting the spatial and temporal coordination and activation of each spinal muscle.
- The corrupted muscle response pattern leads to corrupted feedback to the control unit via tendon organs of muscles and injured mechanoreceptors, further corrupting the muscle response pattern.
- The corrupted muscle response pattern produces high stresses and strains in spinal components leading to further subfailure injury of the spinal ligaments, mechanoreceptors and muscles, and overload of facet joints.
- The abnormal stresses and strains produce inflammation of spinal tissues, which have abundant supply of nociceptive sensors and neural structures.
- Consequently, over time, chronic biomechanical failure develops leading to premature degeneration and long-term pain.
Simply explained, when there is a ligament injury or sprain, the nerves in the ligament fire signals that go to the central nervous system and causes the muscles to react as compensation to bodily injury to stabilize the structure. That in turn sets up another cascade of problems if not compensated for or repaired as the muscle spasticity cannot maintain itself for long periods of time and goes into a posture of tetanus, or perpetual spasm until the lactic acid builds. This is followed by the muscle failing and putting the entire structure in a chronic biomechanically unstable position and causing the bone to remodel or become arthritic.
According to Hauser ET. Al (2013) ligament instability in either subfailures or laxity are a clear cause of osteoarthritis. This is not speculative as the inured will develop arthritis in 100% of the time and is consistent with Wolff’s Law that has been, and continues to be accepted since the late 18th century.
Therefore, as per the above scenario, strain-sprain is an intertwined syndrome that cannot either mechanically or neurologically be separated and will cause arthritis in 100% of the post-trauma instance. How much arthritis and how quickly it will develop is dependent upon how much ligamentous damage there is.
The scope of our information is limited to chiropractic and spinal injuries and conditions. To discuss options on the subject matter, please feel free to ask Dr. Jimenez or contact us at 915-850-0900 .
References:
- What Are Sprains and Strains? National Institute of Health, National Institute of Arthritis and Musculoskeletal and Skin Disorders (2016) Retrieved from:(https://www.niams.nih.gov/health_info/sprains_strains/sprains_and_strains_ff.asp)
- Solomonow, M. (2009). Ligaments: a source of musculoskeletal disorders.Journal of Bodywork and Movement Therapies,13(2), 136-154.
- Panjabi, M. M. (2006). A hypothesis of chronic back pain: ligament subfailure injuries lead to muscle control dysfunction.European Spine Journal,15(5), 668-676.
- Hauser R., Dolan E., Phillips H., Newlin A., Moore R., Woldin B., Ligament & Healing Injuries: A Review of Current Clinical Diagnostics and Therapeutics, The Open Rehabilitation Journal, 2013, 6, 1-20
Additional Topics: Preventing Spinal Degeneration
Spinal degeneration can occur naturally over time as a result of age and the constant wear-and-tear of the vertebrae and other complex structures of the spine, generally developing in people over the ages of 40. On occasion, spinal degeneration can also occur due to spinal damage or injury, which may result in further complications if left untreated. Chiropractic care can help strengthen the structures of the spine, helping to prevent spinal degeneration.
