Friday, May 9, 2014

Topics in Orthopedic Medicine Series: Part 2 -- How Dry Needling Works

In my last blog post, I introduced the concepts of acupuncture and dry needling, comparing & contrasting the two modalities and their roles in treating pain & injury.

In this article, I'll go into the orthopedic uses and scientific rationale of dry needling. Briefly, dry needling can be used in all sorts of interesting ways to influence soft tissue (ligaments, tendons, muscle and fascia) at a micro-level. It is these micro-level effects (i.e. on soft tissue structure and tension, on inter-cellular communications, etc.) that make dry needling an effective treatment for pain and injury either on its own, or in conjunction with other modalities of hands-on musculoskeletal therapy such as massage, osteopathic manipulation, neuro-muscular reprogramming, physical therapy, etc.

(Because the topic of dry-needling can sound intimidating, even invasive, let me take a moment here to talk about how I use needles in an orthopedic context. I love to do a lot of gentle, supportive hands-on therapeutic work with patients dealing with injuries and chronic pain. I use massage to calm a patient's nervous system, relax muscle tension and refine my diagnosis of root causes of pain or injury. I treat these root causes using a combination of manual techniques and acupuncture or dry needling. My work with needles is quite gentle. I appreciate the needles for their ability to create micro-level changes in very specific tissues. My priority is for a patient to feel nourished and supported in the course of their treatment session and for a re-balancing to occur which helps a patient continue to experience a sense of well-being in the days and weeks post treatment.)

Now... let's move on to a summary of the orthopedic uses and scientific rationale of dry needling.

First, let's review the general pattern of injury from repetitive strain or acute trauma.
1. Damaged tissues become inflamed, and contracted into a protective, guarded state.
2. Inflammation and contracture inhibit microcirculation in the affected tissue --- meaning that oxygen can't be delivered and waste can't be removed.
3. Inhibited circulation gives rise to the development of scar tissue.
4. Fibrotic scarring limits the pliancy of soft tissue, so that it can't lengthen and shorten effectively, giving rise to biomechanical disturbances of gait and function, exacerbating pain-causing dysfunction.
5. Fibrotic scar tissue can compress and irritate nerves, exacerbating pain syndromes.

So, what are some of the ways dry needling interrupts this cycle of pain and injury?

1.  Dry Needling Relaxes Tense Muscles, Tones Underactive Muscles

Tight, shortened, hypertonic muscles are a regular aspect of chronic pain, whether it's related to arthritis, nerve irritation, herniated discs or ligament strains. Shortened muscles tug relentlessly on ligaments, tendons and joints perpetuating pain and dysfunction. The muscles that work antagonistically to chronically tight muscles tend, in turn, to be weak, exacerbating structural imbalance.

Dry needling creates a stretch of tiny muscle tissues, which in turn promotes muscle relaxation. It can also stimulate nerve activity, in order to "waken" and tone weak, underactive muscle tissue. Some mechanisms whereby dry needling has been shown to affect muscle tissue include:
  • Stretching muscle tissues stimulates of sensory nerve cells: The gentle rotation of an acupuncture needle in tight muscle tissue tugs and creates a micro-stretch of the muscle fibers. This action seems to stimulate two types of proprioceptive sensory nerve cells -- golgi tendon organs and muscle spindle cells -- resulting in a relaxation of muscle fibers.
  • Dry needling of muscle motor points/motor end-plate zones causes a micro-twitches of muscle fibers:  Motor points, or the point where the motor nerve enters a skeletal muscle, are the most electrically excitable area of the muscle and contain the greatest concentration of nerve endings. Insertion of a needle at a muscle motor point is likely to result in micro-twitches of the muscle (resulting form the depolarization of innervated muscle fiber.) These micro-twitches produce micro-stretch effects on shortened muscle fibers. The micro-stretch induces a relaxation of the muscle.
  • Dry needling increases blood flow and promotes healing of muscle tissue: Chronic muscle tension and spasm can reduce oxygen and nutrient supply, further decreasing muscle function. As was discussed in the section on tendons and ligaments above, dry needling causes microscopic trauma to soft tissue, setting in motion a cascade of processes that help heal and desensitize the tissue. Micro-bleeding nourishes cells and washes away sensitizing substances. Platelet-derived growth factors facilitate DNA synthesis and stimulate collagen and protein formation. Needling can break up fibrotic scar tissue that has entrapped nerve endings and can replace hyperactive pain receptors with non-painful ones.
As a chronically tight muscle relaxes and heals, it produces less mechanical traction on pain sensitive structures like intramuscular nerves, blood vessels and tendons. It also pulls less on bony joints, decreasing wear and tear of joints and allowing the body to balance itself more efficiently in space. In supporting the rebalancing of antagonistic muscle groups, dry needling be an effective adjunct to manual neuromuscular reprogramming therapies.

2. Dry Needling Strengthens Ligaments & Tendons

Ligament weakness (referred to as laxity) or partial ligament tears are common sources of chronic pain. Joints commonly affected by ligamentous laxity are sternoclavicular, acromioclavicular, sacroiliac, pubic symphysis, knees, ankles & sometimes shoulders.

Tendinosis, chronic degeneration of tendons, and partial ruptures of tendons can also cause chronic pain and dysfunction -- common in shoulder, wrist, elbow and heel. Chronic tendinopathy can be marked by repeated cycles of re-injury, aborted healing processes, scar tissue and inflammation.

Ligaments and tendons are relatively poorly vascularized, slow to heal from injury and, thus, commonly involved in chronic pain syndromes and persistent slow-to-heal injury patterns.

Dry needling can be used to strengthen tendons and ligaments by creating micro-injuries to the tissue, thereby inducing a local inflammatory reaction. Researchers believe dry needling can promote beneficial bleeding, opening up new channels through degenerated soft tissue. The mechanical disruption brought about by the introduction of a needle can transform a failed/aborted healing process into a therapeutic healing process. Basically, the mechanical micro-trauma caused by needling sets off a cascade of inflammatory processes:
  • Immune factors enter the area to break down and clear away scar tissue.
  • Blood cells, plasma, platelets and growth factors permeate poorly-vascularized tissue.
  • Fibroblasts generate collagen and elastic fibers, adding strength to the connective tissue.

3.  Dry Needling Can Influence the Nervous System to Relieve Pain

Dry needling may affect neurotransmitter activity and spinal reflexes, alleviating pain perception locally or segmentally (anatomical regions innervated by spinal nerve segments.) Periosteal needling techniques (needling soft tissue attachments to bone) can regulate sympathetic nerve fibers around the periosteum, increasing blood circulation to the area.

4. Dry Needling Can Regulate Fascia

Research has shown a correspondence between major acupuncture points and sites of convergence of plains in the network of fascia, the soft connective tissue that permeates the entire body. Fascia is currently being studied with increasing interest for its role in providing stability, tensegrity, communication and integration of the whole body. Acupuncture and dry-needling have mechanical and electrical affects on fascia, regulating tensegrity throughout the body.

Dry needling produces an affect on fascia similar to its affect on muscles and tendons. An inserted needle grasps and twists the soft tissue in a gentle manner creating a whorl of tissue around the needle. It thereby alters tension at critical junctions of the connective tissue network that supports the body. Research also shows that needling promotes particular electrical affects between nerves and surrounding ground substances and between inner and outer epidermal layers of the tissue, affecting inter-cellular communication and ultimately levels of tension at connective tissue trusses.

In conclusion, dry needling -- when it's performed with a clear diagnosis of injury and understanding of involved anatomical structures -- can promote micro-, cellular or tissue-level, changes in soft tissue (ligaments, tendons, muscle, fascia, nerves.) These micro-changes can have profound effects on the structure of soft tissue, promoting changes in tension level, alleviating pain, supporting tissue healing and altering the way the body balances itself in space. By virtue of its micro-level affects, dry needling may produce longer lasting affects on soft tissue than massage and manual orthopedic therapies alone. It is an excellent adjunct to other forms of musculoskeletal therapy.