Dry Needling is an intervention that uses fine filiform needles to penetrate skin and stimulate trigger points to manage neuromuscular pain and movement impairments. This technique is utilized by physiotherapists who obtained postgraduate education and training in dry needling. Dry needling is also know as intramuscular therapy, or intramuscular stimulation (IMS).
What is trigger point and why use Dry Needling/IMS?
A trigger point is a muscle “knot” that is sore and painful to the touch. The pain can also be felt on the other parts of the body. According to a pain science article, trigger points are constant source of painful stimuli that can make our body sensitive to pain. “Dry needling cannot only reverse some aspects of central sensitization, it reduces local and referred pain, improves range of motion and muscle activation pattern, and alters the chemical environment of trigger points.” 
Dry needling is just one of the intervention options that is provided a physiotherapist skilled in this technique as part of your treatment plan to reduce your pain and get back on your feet.
APTA. Description of dry needling in clinical practice: An educational resource paper. (2013). Retrieved from http://www.apta.org/StateIssues/DryNeedling/ClinicalPracticeResourcePaper/
 Ther, J. Mann. Dry Needling- Peripheral and central considerations. Journal of Manual and Manipulative Therapy. 2011 Nov; 19(4): 223–227.doi: 10.1179/106698111X13129729552065