Frozen shoulder is a condition characterized by progressive pain and stiffness in the glenohumeral joint. This stiffness occurs when the connective tissue capsule surrounding the shoulder joint thickens, contracts, and restricts motion. Transcutaneous Electrical Nerve Stimulation (TENS) is a non-invasive, drug-free method that uses mild electrical currents to provide temporary relief from this persistent pain. Applying a TENS unit helps manage discomfort and supports the physical therapy needed to regain mobility.
How TENS Addresses Frozen Shoulder Pain
TENS modulates the body’s perception of pain through two primary mechanisms. The most immediate effect is explained by the Gate Control Theory, where non-painful electrical input overrides or “closes the gate” on painful signals traveling to the brain. High-frequency electrical pulses stimulate large nerve fibers, effectively blocking the transmission of pain signals carried by smaller fibers at the spinal cord level.
A second, more sustained mechanism involves the body’s own pain-relieving chemistry. When TENS is applied at a lower frequency, it stimulates the release of endogenous opioids, such as endorphins and enkephalins. These natural neurochemicals act within the central nervous system, providing a longer-lasting, systemic analgesic effect beneficial for chronic conditions like frozen shoulder.
Step-by-Step Pad Placement
Proper placement of the electrode pads is crucial for maximizing pain relief, as the current must effectively cover the affected joint capsule. For generalized frozen shoulder pain, a common and effective configuration involves cross-joint placement using two pads. One pad should be positioned anteriorly (on the front) over the deltoid muscle, and the second pad should be placed posteriorly (on the back) over the shoulder blade or posterior capsule.
This front-to-back arrangement ensures the electrical current flows directly through the shoulder joint, stimulating the nerves within the tight connective tissues. For pain localized to the top of the shoulder or the upper trapezius muscle, use a vertical placement. Place one pad superiorly near the neck and the other pad inferiorly toward the bulk of the deltoid muscle.
To address stiffness and improve range of motion, position the pads to target surrounding muscle groups, such as the rotator cuff. Place the pads to bracket the muscle belly of the supraspinatus or infraspinatus, focusing on muscle bulk rather than directly on the bone. Pads must always be placed on soft, muscular tissue and kept at least one to two inches apart to ensure correct current flow.
The specific source of pain can shift as frozen shoulder progresses, requiring users to experiment by moving the pads slightly until they find the position that provides the most noticeable reduction in discomfort. Ensure the electrode pads maintain full contact with clean, dry skin to ensure optimal conductivity and prevent irritation.
Optimal Settings and Usage Protocols
The most effective TENS settings for frozen shoulder depend on whether the goal is immediate, short-term relief or longer-lasting, chronic pain modulation. For sudden or acute pain flares, a high-frequency setting of 80 to 120 Hertz (Hz) is generally recommended. This high-frequency stimulation is designed to activate the Gate Control mechanism, providing rapid pain blocking while the unit is operating.
To achieve a deeper, more sustained pain relief associated with the release of endorphins, a low-frequency setting below 10 Hz, often between 2 and 10 Hz, is preferred. This setting is typically used for managing the pervasive, chronic ache characteristic of the frozen shoulder’s later stages. Many modern TENS devices also offer a Burst mode, which delivers low-frequency bursts of high-frequency pulses, proving highly effective for persistent chronic pain.
Regardless of the frequency chosen, the intensity, or amplitude, should be adjusted to a level that produces a strong but non-painful tingling sensation beneath the electrodes. The user should feel a comfortable sensation that is noticeable but does not cause a muscle contraction or any jolting feeling. A typical TENS session for frozen shoulder pain relief lasts between 20 and 40 minutes and can be repeated two to three times per day as needed for pain management.
Safety Guidelines and Contraindications
While TENS is a safe, non-invasive method, there are specific conditions and locations where its use is advised against.
Contraindications
- Individuals with an implanted electronic device, such as a pacemaker or an internal defibrillator, must not use a TENS unit, as the electrical impulses could interfere with the device’s function.
- TENS should be avoided if there is active malignancy in the treatment area or if the user has a history of epilepsy, as the electrical stimulation may potentially trigger a seizure.
- Pads must never be placed over broken, infected, or damaged skin, including areas with rashes or open wounds, because this can increase the risk of irritation or infection.
- The electrodes should also never be placed over the front of the neck, eyes, or transcranially, which means across the head.
- Use over the abdomen during pregnancy is also prohibited.
Before beginning TENS therapy, especially for a chronic condition like frozen shoulder, consult with a healthcare professional or a physical therapist. They can confirm the diagnosis, demonstrate the correct pad placement, and help determine the optimal frequency and intensity settings. Consulting with a professional ensures the device is used safely and as part of a comprehensive recovery plan.