Modalities and Manual Techniques in Sports Medicine Rehabilitation

Modalities

Modalities such as cryotherapy (ice), electrical stimulation, heat, ultrasound, and laser are commonly applied to the body to affect the inflammatory cascade and to reduce pain. Ice is probably the most commonly applied treatment and is part of the standard of care. For most acute injuries the acronym POLICE ( P rotect, O ptimal loading, I ce, C ompression, E levation) should be followed ( Fig. 32.1 ). Electrical stimulation has been used in rehabilitation for thousands of years and dates back to the ancient Olympic Games in Greece when clinicians used electrical eels to treat athletes’ injuries. Today electrical currents are applied as either transcutaneous electrical nerve stimulation (TENS) or as neuromuscular electrical nerve stimulation (NMES) to reduce pain or stimulate a muscle contraction. Newer forms of electrotherapy, such as patterned electrical nerve stimulation (PENS), have additional application in muscle activation and recruitment. Ultrasound and laser are often termed biostimulators since they use mechanical (acoustical energy) or light energy to stimulate cellular processes within the tissues. Thus the types of energies and equipment available for clinical use are continually expanding.

Literature that supports the use of therapeutic modalities varies and researchers often try to identify physiologic mechanisms or responses when these agents are applied. Studies on healthy individuals, as is often the case with cryotherapy studies, confound the literature since the neuromuscular changes induced with ice application would be different without pathology. Garnering evidence to support the use of modalities is difficult combined with the fact that clinical trials are difficult to control. For example, to study whether TENS enhances pain modulation in a specific injury, the researcher would need to control all other therapies including ice, oral analgesics, and activity. Typically, once a patient feels improvement, he or she increases their activity level, which can, in turn, result in more discomfort. The use of patient-reported outcome scales, physical measures of edema, range of motion (ROM), strength, and data from activity monitors can help provide evidence for specific treatments. Furthermore, modalities all have parameters that affect the dosage, which should be consistently applied and modified when appropriate. For example, electrical currents have a variety of waveforms, phase durations, pulse frequencies, and recommended intensities to elicit the desired response. Ultrasound can vary in frequency, duty cycle, and intensity; and lasers vary in wavelength, intensity, and possibly duty cycle. The area treated, the amount of tissues exposed, and how often the treatment is delivered can also affect the outcome. Thus the clinician is expected to understand the parameters and adjust them properly according to the desired outcome. Since modalities often apply thermal, electrical, acoustical, or light energy to the body, precautions include cardiac pacemakers (or implanted electromagnetic devices), sensory loss (especially to temperature changes), and peripheral artery disease that affects normal physiology in the extremities. Specific precautions should always be applied regarding the specific technique.

Manual Therapy

Similar to modalities, MT is a passive, nonsurgical type of conservative management that involves skilled movements applied by clinicians to the patient's body that directly or indirectly targets a variety of anatomical structures or systems. MT is used to assess, diagnose, and treat a variety of symptoms and conditions that are intended to modulate pain; improve tissue extensibility; increase ROM; induce relaxation; mobilize or manipulate soft tissue and joints; and reduce soft tissue swelling, inflammation, or restriction. Health care practitioners implement MT when the examination findings, diagnosis, and prognosis indicate the use of these techniques to decrease edema, pain, spasm, or swelling; enhance health, wellness, and fitness; improve or maintain physical performance; increase the ability to move; or prevent or remediate impairment in body functions and structures, activity limitations, or participation restrictions to improve physical function. Precautions, and contraindications for MT include joint pain with the technique, joint effusion, unknown pathology, auto-immune diseases, fracture, tumor, infection and osteoporosis. MT should be avoided with nerve and vascular pathologies where movement and pressure can exacerbate the condition. Although these techniques can be helpful and useful, there is no evidence that any one of them is the only way or even the best way to treat a particular condition.

There are many MT techniques with different names and uses. There are even types that offer practitioners certifications in a particular technique. You may see these listed as trigger point release (TPR), proprioceptive neuromuscular facilitation (PNF), muscle energy technique (MET), strain-counterstrain, active release technique (ART), cranio-sacral therapy, myofascial release, positional release therapy, and others. Most of these MT techniques may be categorized into four major groups: (1) manipulation (high velocity low amplitude—HVLA), (2) mobilization (nonthrust manipulation), (3) stretching, and (4) muscle-modifying techniques.

Collectively, the process of interventions with either modalities or MT is grounded on clinical reasoning to enhance patient management for musculoskeletal pain by influencing factors from a multidimensional perspective that have potential to positively impact clinical outcomes. The influence of biomechanical, neurophysiologic, psychological, and nonspecific patient factors as treatment mediators and/or moderators provides additional information related to the process and potential mechanisms by which the treatment may be effective. Additionally, the definition and purpose of MT varies across health care professionals. As health care delivery advances toward personalized approaches, there is a crucial need to advance our understanding of the underlying mechanisms associated with MT and modality effectiveness.

Modalities have been shown to be effective when applied in a variety of ways to various pathologies. MT has been shown to be effective for increasing function and pain reduction in the treatment of musculoskeletal disorders including low back pain, carpal tunnel syndrome, knee osteoarthritis, and hip osteoarthritis. Moreover, recent studies have provided even stronger evidence when participants are classified into sub-groups. Refer to Table 32.1 for a summary. Despite the literature supporting its effectiveness, the mechanisms of these treatments are not well established.

Pain Modulation

Pain is perhaps the most common factor in any sports injury or orthopaedic condition and is involved with the inflammatory process. Pain is useful since it alerts the patient that there is a problem, but it can begin a cascade of factors that can change motor function that is designed to protect the injured body part. For example, friction in the glenohumeral joint of a swimmer may begin with some pain. Unknown to the swimmer, the supraspinatus muscle becomes inhibited. Although there is discomfort, the swimmer continues his workout and the poor motor function prevents adequate stabilization and depression of the humeral head. Minor adjustments in the scapular position permit another 20,000 to 30,000 strokes with no real change in the ability to perform. However, the change in mechanics may result in bursitis, tendinopathy, and impingement. Resolving the pain in this case is imperative to restoring the mechanical function of the supraspinatus.

Pain is a complex neurophysiologic phenomenon and methods to treat pain include medications as well as physical agents and MT. Medications typically act on the chemical cascade of the inflammatory process, and include non-steroidal antiinflammatory drugs (NSAIDs) and steroids. Various other analgesics, both narcotic and nonnarcotic, act on the chemical neurotransmitters throughout the nervous system. Physical agents and manual therapies act by stimulating various sensory systems to elicit endogenous neurotransmitters or by creating alternative sensory input that reduces the painful input. Regardless of the method used for analgesia, it is important to restore normal stimulus to the muscle system. Returning to the swimmer, when pain is reduced, the supraspinatus needs to be retrained to stabilize and depress the humeral head during the overhead motion. Just relieving pain without proper attention to the inhibited muscle group would only provide a temporary solution.

To simplify pain modulation for the purposes of this chapter, three manners of pain modulation will be presented. Sensory, rhythmical, and noxious mechanisms can explain the majority of pain modulation from common therapies ( Table 32.2 ). Then, various treatments within each theory can be presented.

Manual Therapy

The pain-modulating effects of most MT techniques has been suggested to be mainly neurophysiologic in origin, and may be mediated by the descending modulatory mechanisms (rhythmical and noxious). Current research suggests that this neurophysiologic response to MT is responsible for clinically significant decreases in pain. It appears that different types of MT may work through different mechanisms ( Table 32.3 ). Understanding the mechanisms may help clinicians choose which therapy is most appropriate for each patient, and may lead to more effective therapies in the future.

In a recent study investigating the effect of four MT techniques (manipulation/mobilization, muscle energy, massage, strain-counterstrain) performed on subjects with sites of muscle hypertonicity, tenderness, and joint restriction revealed that blood levels of β-endorphin and N-palmitoylethanolamide were elevated after treatment when compared to baseline. The greatest biomarker alteration was experienced in subjects with chronic low back pain.

Cryotherapy

Ice is the mantra for clinicians as the first line of defense for pain. Ice application is an effective analgesic and can control pain for several hours after an activity. Cooling the temperature of an inflamed area will also diminish the metabolic activity in the area, slow the production of inflammatory cells and potentially decrease the need for oxygen in the tissues. Following an acute injury, ice is combined with compression and elevation to help control swelling, and as mentioned previously, it should be combined with protection of the structure and controlled or optimal loading. This treatment can be used conveniently at home and can be administered several times per day.

Ice has been shown to be an effective modulator of pain in the treatment of soft tissue injuries. Many clinicians believe that the cold application results in the spinal gate mechanism to diminish pain response from the focal area. However, the application of cryotherapy is typically noxious, with the patient perceiving cold, burning, aching, and then numbness. The mechanism for pain reduction is likely to be associated with a more complex neurologic pathway that stimulates smaller diameter nerve fibers, as described in the noxious pain modulation theory. Ice has been shown to slow nerve conduction velocity and increase pain threshold. Research evaluating pain relief is often confounded by increases in physical activity. Any positive change in activity should be interpreted as a reduction in discomfort that often limits function.

With the recent attention to elite athletes receiving treatment with cold baths or cold-water immersion following exercise, ice has been examined as a postrecovery modality. Again, few data support the use of cold therapy as a mechanism to prevent the inflammatory effects of exhaustive exercise or to minimize the effects on subsequent performance. However, cold water immersion has been shown to help regulate core temperature when exercising in the heat. Similar to other studies, methods to examine appropriate temperature, and the time and timing of the treatment are inconsistent, particularly when used as a recovery modality. Guidelines for temperature should be followed, since extreme cold temperatures have been associated with increasing the inflammatory process. Temperatures below 50°F should not be used, despite the habituation to cold therapy, particularly with cold water immersion.

There are numerous methods to apply ice or cryotherapy. An plastic bag filled with crushed ice is a convenient and inexpensive ice pack. Air insulates as an interface, so crushed ice is optimal, especially since cubes may be uncomfortable since they may increase pressure. Ice penetrates up to 4 cm, so it can be used to decrease the temperature of many superficial joints. However, adipose insulates against cooling, and longer treatment times are required depending on the treatment area. Icing a large muscle group, such as the quads, hamstrings, or hip, may require 40 minutes or more of treatment time, while the ankles and knees may require only 10 to 15 minutes of cooling for a therapeutic effect. Generally, the more adipose present over the treatment site the longer the treatment required for adequate cooling.

Compression is often used in conjunction with ice and may be a confounder when investigating the therapeutic effects of cooling, since both may affect the development of edema. Plastic wraps are often used to secure ice bags to the body so that sitting during the treatment is not necessary. Caution should be used with compressive wraps since a tourniquet effect can occur. Additionally, pressure with the cold can result in damage to superficial nerves, such as the ulnar nerve when treating the elbow, or the fibular nerve when treating the knee.

Electrical Stimulation

Electrical stimulation is characteristically applied for pain relief. There are numerous waveforms with specific parameters that permit a clinician to adjust intensity (amplitude), phase duration, and pulse frequency, or there are clinical units that select combinations of parameters with the push of a button. Most units for therapeutic electrical stimulation can be classified as TENS units since they are applied superficially, passing a current through the skin to affect an intact nervous system. Subclassifications of stimulators are used to distinguish the goal of the treatment (either for pain relief or for facilitation of motor function) or the waveform of the stimulator (high voltage, biphasic, interferential, etc.). For the purposes of this chapter, sensory TENS units will be distinguished from neuromuscular stimulators (NMES) since the goal of the treatments are different. The sensory stimulators are primarily used for pain relief and are capable of eliciting a motor response, but the purpose is not to facilitate the muscle function. NMES units, conversely, are designed to stimulate a motor nerve to elicit a muscular response that may be used during rehabilitation to improve the ability to contract a specific muscle.

Transcutaneous Electrical Nerve Stimulation

TENS operates by stimulating afferent nerves (sensory) to promote pain modulation. There are several proposed mechanisms for pain modulation, and the stimulation parameters associated with each mechanism are designed to enhance the effectiveness of that neuromodulation mechanism. For example, in the gate theory, large diameter sensory nerves are targeted to result in an inhibitory effect of the smaller pain fibers in the spinal cord. “Sensory” TENS is applied to target those large diameter nerve fibers to close the “gate” to modulate pain. Thus the parameters associated with “sensory” TENS are designed to maximize the stimulation of those large diameter nerves. Since the neuromodulation techniques are complicated, many modality companies have simplified the design of stimulators so the clinician can select the type of stimulation they want and the parameters will be packaged appropriately. However, in order for clinical trials to evaluate the usefulness of TENS, the parameter selection should be specified so that appropriate comparisons can be made, particularly with systematic reviews.

For the purposes of this chapter, the pain modulation mechanisms are categorized as (1) sensory TENS, (2) motor TENS, and (3) noxious TENS. These are common methods of applying electrical stimulation for pain relief and have application for injury management. The sensory TENS mechanism, as previously mentioned, is based on the gate theory and inhibits pain in the spinal cord. It is often used with acute injuries since the stimulation is comfortable, but the analgesic effect is short lived. This treatment is appropriate for use prior to therapeutic exercise or after activity for pain management. The motor TENS mechanism is sometimes a misnomer, since an electrically produced muscle contraction is not required for this mechanism. Many times, there is a rhythmical muscle contraction and therefore it is not used as frequently for acute injuries. The neural mechanism is associated with a descending analgesic pathway, meaning that the pain is first perceived by the cortex. Then, specific brain centers, such as the pituitary gland, are signaled to produce precursors to the endogenous opioid, endorphin. Similarly, precursors are released that signal the adrenal glands to produce the hormone cortisol. This neural mechanism is elicited by rhythmical stimulation of A delta fibers, which are the larger of the pain fibers (but smaller than A beta fibers). Finally, noxious TENS, as its name implies, produces a strong, uncomfortable stimulation, similar to a bee sting. Theoretically, that type of stimulation targets the smallest pain fibers to alert specific brain centers to release enkephalin (another endogenous opiate), and serotonin, which both have powerful analgesic qualities. The parameter selection in the stimulator is based on the attempt to preferentially stimulate the target nerve in each of these pain modulation schemes.