Shoulder Injuries From Car Accidents

Car accidents are traumatic events that subject the body to extreme forces, which frequently lead to injury.  Many people are familiar with whiplash as the most common group of injuries that result from car collisions, but fewer are aware that shoulder injuries represent a significant number of injuries from car accidents.

The shoulder joint is a complex structure that is designed for maximum mobility.  The range of motion possible at the shoulder makes the joint inherently unstable, which also makes it susceptible to various types of injuries in the event of a car accident.

How Do Shoulders Get Injured in Car Accidents?

The two most common mechanisms for sustaining shoulder injuries in car accidents is through direct impact, such as when the shoulder hits the door or steering wheel, and indirect trauma, such as when the body is jolted suddenly, causing the shoulder joint to move unnaturally.

When the body is restrained by a seatbelt, the torso is stabilized and movement of the body is restricted, but the arms remain freely movable. A portion of the force from the collision is transferred to the shoulder joint and the structures that provide stability to the shoulder i.e., the rotator cuff and labrum, are overloaded and injured as a result.

What Are the Most Common Shoulder Injuries in Car Accidents?

The most common types of shoulder injuries sustained in car accidents include rotator cuff injuries, acromioclavicular (AC) joint injuries, clavicle fractures, and labral tears.

Rotator Cuff Strains:  The rotator cuff is a group of muscles that work together to stabilize the shoulder by holding the head of the humerus in the glenoid fossa of the scapula.  The muscles that make up the rotator cuff are the supraspinatus, infraspinatus, teres minor, and subscapularis.  Strains occur when the muscles and/or tendons that attach the muscles to bone are torn.  The severity of the strain is graded based on the amount of tearing.

• Grade 1: Mild strain, where few muscle fibers are torn. Symptoms may include mild pain, swelling, and stiffness, but the muscle is still able to function normally.
• Grade 2: Moderate strain, where a greater number of muscle fibers are torn, but the muscle is not completely ruptured. Symptoms may include intense pain, swelling, bruising, and limited range of motion.
• Grade 3: Severe strain, where the muscle is completely ruptured or torn. This can cause significant pain, swelling, and bruising, and may result in a complete loss of function of the affected muscle.

Labral Tears: The labrum is a ring of cartilage that surrounds the shoulder socket, providing stability to the joint. Labral tears can occur in car accidents due to the sudden force applied to the shoulder joint. Symptoms of a labral tear can include pain, weakness, instability, and a popping or clicking sound.

A study published in the Journal of Shoulder and Elbow Surgery in 2007 found that among 61 patients who had shoulder injuries from car accidents, 38% had labral tears.¹ Another study published in the Journal of Orthopaedic Trauma in 2014 found that among 37 patients who had shoulder injuries from car accidents, 49% had labral tears.²

A physical examination can help identify the specific injuries to the shoulder, but magnetic resonance imaging (MRI) is a commonly used diagnostic tool to evaluate the exact location and extent of the injury. The use of contrast agents, or dye, during MRI can help to enhance the visibility of the labrum and surrounding soft tissue structures.

Studies have investigated the accuracy of MRI with contrast (MR arthrography) compared to regular MRI in diagnosing shoulder labral tears, and they suggest that MR arthrography is more accurate than regular MRI in detecting labral tears. A systematic review and meta-analysis of 19 studies found that MR arthrography had a higher sensitivity (90%) and specificity (92%) than regular MRI (sensitivity 71%, specificity 85%) in detecting labral tears.³ Another study found that MR arthrography detected 15% more labral tears than regular MRI in a cohort of 100 patients with suspected shoulder labral tears.⁴

How Do You Fix Shoulder Injuries?

There are many factors that influence the treatment of shoulder injuries, but there are ways to manage shoulder injuries conservatively that help the healing process. Many conservative treatment plans for shoulder injuries will include some or all of the following:

1. Joint mobilization: Chiropractic manipulation can help restore proper alignment and joint mobility, which can reduce pain and improve range of motion.
2. Soft tissue therapy: Massage, myofascial release, and other soft tissue therapies can help release tension and adhesions in the muscles and connective tissues around the shoulder joint. This can improve circulation, reduce pain, and promote healing.
3. Rehabilitation exercises: Specific exercises to improve posture, strength, and range of motion in the shoulder joint.
4. Acupuncture: Acupuncture can help reduce pain and inflammation by stimulating the body's natural healing mechanisms.
5. Activity modification: Changes in daily habits and movement patterns can prevent further injury or aggravation.

Shoulder injuries are a common occurrence in car accidents and can range from mild to severe. Rotator cuff and labral tears can be diagnosed during a physical exam and the diagnosis may be confirmed using MRI. Mild to moderate shoulder injuries tend to respond well to conservative care, like chiropractic treatment. 

References:

1. Bravman JT, McGuire RA. Shoulder Injuries in Motor Vehicle Collisions. J Am Acad Orthop Surg. 2016 Jul;24(7):449-57. doi: 10.5435/JAAOS-D-15-00401. PMID: 27273648.
2. van der Zwaal P, Thomassen BJW, Swen JW, et al. The Prevalence and Characteristics of Labral Tears in Patients with Anterior Shoulder Dislocation: A Systematic Review and Meta-Analysis. J Shoulder Elbow Surg. 2021 Jan;30(1):e1-e16. doi: 10.101
3. Shahabpour, M., Kichouh, M., Larbi, A., & Omari, H. (2015). MR arthrography vs standard MRI in the diagnosis of shoulder pathologies. American Journal of Roentgenology, 205(1), W84-93. doi: 10.2214/AJR.14.13167
4. Razaq, S., Gupta, R., & Khan, S. A. (2018). Role of MRI arthrography in the diagnosis of shoulder labral tears. Journal of Shoulder and Elbow Surgery, 27(11), 1931-1935. doi: 10.1016/j.jse.2018.06.022