Abstract
Background
Dry needling (DN) has emerged as a popular therapeutic intervention for managing musculoskeletal pain. While major adverse events are generally rare, those that have been reported in vulnerable areas such as the spine and thorax can be serious and warrant further investigation regarding safe techniques in and around these areas.
Purpose
The purpose of this study was to reproduce the methods employed by Williams et al. but with an inferior-medial multifidus DN technique to determine if a dry needle can penetrate the ligamentum flavum (LF) and breach the spinal canal at the thoracolumbar junction.
Study Design
Descriptive Cadaveric study.
Methods
The procedure was performed on a cadaver in the prone position. The needle was advanced under ultrasound guidance to determine if a 0.30 x 40 mm dry needle inserted lateral to the spinous process of T12 and directed inferior-medially could penetrate the LF and enter the spinal canal.
Results
A 0.30 x 40 mm dry needle inserted 1.9 cm lateral to the spinous process of T12 was able to traverse the space between the vertebral laminae of T12 and L1, penetrate the LF, and enter the spinal canal with an inferior-medial needle angulation of 33-degrees medial and 18-degrees inferior.
Conclusion
The results of this study demonstrate the feasibility of a dry needle entering the spinal canal at the thoracolumbar junction using an inferior-medial technique. These findings support the potential role of ultrasound guidance in the training and clinical practice of DN, especially in regions where safety issues have been documented.
Level of Evidence
Level IV.
Keywords: cadaver, dry needling, multifidus, safety considerations, ultrasound
INTRODUCTION
Dry needling (DN) has emerged as a popular therapeutic intervention for managing musculoskeletal pain, with more than half of physical therapists surveyed using DN in the treatment of their patients.1 Numerous authors have reported DN as an effective tool when used in conjunction with other interventions to manage back pain.2–6 While major adverse events due to DN are reported to be rare,7 those that have been reported to occur from DN around the spine and thorax can be serious, and include pneumothorax, quadriparesis related to acute cervical epidural damage, and hemiplegia related to subdural or epidural hematomas.8–12 In addition, the lack of a standardized method for reporting adverse events likely leads to underreporting, which suggests there may be more adverse events occurring than those currently documented in the literature.1,13
Dry needling of the multifidi is a common intervention for the treatment of back pain and is one that has generally been regarded as a safe technique given that the bony backdrop of the lamina is considered to be protective. While using a bony backdrop, such as the lamina, is thought to decrease the risk of inadvertently entering other unintended structures, this DN strategy for the multifidi presumes the needle tip will not land between adjacent vertebral lamina, where it could potentially pierce through the ligamentum flavum (LF) and enter the spinal canal. Despite this presumption, there is no specific DN technique that has been universally accepted as being the safest approach to ensure the needle successfully reaches the protective bony backdrop of the lamina.
Reported techniques for DN the multifidi suggest that needles should be placed 1-2 cm lateral to the lumbar spinous process and directed medially or inferior-medially until the needle reaches the lamina.14–20 Both the inferior and the medial needle orientation documented among the inferior-medial techniques vary considerably, ranging between 15° and 45°.14,15,17–21 Williams et al. demonstrated that a 0.30 x 50 mm needle can penetrate the LF and enter the spinal canal at the thoracolumbar junction with a needle inserted approximately 1.0 cm lateral to the spinous process, directed in a posterior-anterior orientation, and inclined medially at a 22-degree angle from vertical.22 The purpose of this study was to reproduce the methods employed by Williams et al. but with an inferior-medial multifidus DN technique to determine if a dry needle can penetrate the LF and breach the spinal canal at the thoracolumbar junction.
METHODS
The study was performed on a 77-year-old female, fresh-frozen, lightly-fixed cadaver at Middle Tennessee School of Anesthesia. Ultrasound scans were performed by a certified registered nurse anesthetist with over 20 years of diagnostic ultrasound imaging experience and 15 years of experience performing and teaching regional anesthesia, including ultrasound-guided spinal anesthesia procedures. The fresh/lightly embalmed cadaver was received through the Willed Body Program at The University of North Texas Health Science Center. Exemption from Institutional Review Board approval was granted by Advarra IRB (Pro00070509).
The cadaver was placed in the prone position with the lumbar spine in a relatively neutral position. A Sonosite Edge II ultrasound system with an rC60xi 5-2 MHz curvilinear array transducer (Bothell, WA) was placed in a parasagittal orientation with the orientation indicator facing cephalad. The sacrum, L5-S1 interspace, and L5 spinous process were identified. The transducer was moved cephalad until the interspace between T12 and L1 was identified. A DBCTM ProMaxx 0.30 x 40 mm dry needle was inserted approximately one finger-breadth lateral to the spinous process of T12 and directed in an inferior-medial angulation toward midline while being visualized by ultrasound. If the needle reached the lamina, it was left in place, and another needle was placed in very close proximity. The process was repeated until a needle breached the LF and entered the spinal canal. After the final attempt, measurements were taken to determine the distance along the skin between the needle and the spinous processes and the medial and inferior needle angulations for the needle which entered the spinal canal.
A range of needle lengths between 40 mm and 100 mm have been described when studying DN techniques in the thoracic and lumbar regions, with 50 mm and 60 mm being the most commonly utilized in clinical practice, depending on the spinal location.14,16–21,23 Dry needle length is selected based on the size of the patient’s soft tissue and musculature.14,24 In the previous study by Williams et al., a 50mm needle was used,22 whereas this study utilized a shorter needle (40 mm).
RESULTS
A 0.30 x 40 mm dry needle was able to traverse the space between the vertebral laminae of T12 and L1, penetrate the LF, and enter the spinal canal on the fourth attempt. The needle that entered the spinal canal was located 1.9 cm lateral to the spinous process of T12. More specifically, the insertion point was approximately 4.3 mm inferior to the center of the spinous process of T12, the medial angulation of the needle was 33-degrees from vertical (Figure 1), and the inferior angulation of the needle was 18-degrees (Figure 2).
Figure 1. Medial needle inclination of 33 degrees.
Figure 2. Inferior needle inclination of 18 degrees.
DISCUSSION
The purpose of this study was to reproduce the methods employed by Williams et al. but with an inferior-medial multifidus DN technique to determine if a dry needle could penetrate the LF and breach the spinal canal at the thoracolumbar junction. The results of this study corroborate a previous finding that a dry needle can enter the spinal canal at the thoracolumbar junction using a medial technique, and also when using an inferior-medial technique.22 The thoracolumbar junction is an area of complex anatomy and an area of presumed increased risk and therefore, it may be important for physical therapists to consider the overall safety of DN techniques when treating this area of the spine.
This study is the second to use ultrasound guidance to document dry needles entering the spinal canal at the thoracolumbar junction when using techniques outlined in the literature for targeting the multifidi. While other healthcare professions utilize ultrasound guidance as a standard tool for training and practicing needle techniques, ultrasound guided DN during training courses for physical therapists is not common practice, nor is ultrasound guided DN routinely used in clinical physical therapist practice in the United States.25 Using ultrasound guidance during DN training may prove valuable, especially in light of the poor reliability and validity of palpation-based methods seen as cornerstone in DN training.26,27 Ultrasound guidance offers a potential solution by providing enhanced visualization and accuracy. Additionally, using ultrasound during DN training may promote trainee’s tactile sensation and spatial awareness by allowing trainees to visualize anatomical structures in real-time to correlate tactile sensations as different tissue layers and structures are engaged. Given the fact that some physical therapists are now being trained in ultrasound imaging techniques in entry-level physical therapy programs,28 as well as dry needling,29 it stands to reason that ultrasound guided DN, especially in areas of increased risk, may be an important consideration in future training and clinical use to improve patient safety.
There are a number of procedural considerations and limitations in this study. First, it is important to recognize that this study did not attempt to determine the likelihood of penetrating the spinal canal during the clinical use of DN, but merely explored the possibility of a dry needle entering the spinal canal when using a technique commonly described in the literature for the multifidi. Therefore, specific needle locations relative to the spinous process and needle angulations are intended to help with replication in future studies, not to be extrapolated as safe/unsafe zones for DN to be performed. Given that the determination of the center of the spinous process was based on palpation and neither imaging nor dissection were used to confirm a true center of the spinous process, generalization of unsafe zones relative to the spinous process would be speculative and inappropriate.
Second, this study was a feasibility study using a 77-year-old, fresh-frozen, lightly-fixed, female cadaver. It is plausible that differences in tissue turgor in cadavers versus living subjects, as well as the age of the donor may have impacted the outcomes. Several authors have documented that the thickness and stiffness of the LF increase linearly with the degree of disc degeneration30 and age31 and can also differ between various lumbar segments.32 The donor in this study was 77-years-old and thus, similar to 90% of individuals 65 years and older, very likely had disc degeneration.33 The age-related changes in the donor used in this study may have actually been protective; however, the dry needle was still able breach the spinal canal. Studies using a larger sample size may have resulted in different outcomes if performed in vivo and with more variability in subjects.
CONCLUSION
The results of this study demonstrate the feasibility of a dry needle entering the spinal canal at the thoracolumbar junction using an inferior-medial technique for the multifidi. These findings support the potential role of ultrasound guidance in the training and clinical practice of DN, especially in regions where safety issues have been documented. Evaluating the safety profiles of DN techniques currently being used, exploring the feasibility and potential impact of ultrasound guidance during training and clinical practice, and examining the clinical outcomes associated with ultrasound-guided dry needling are important next steps.
References
- A survey of American physical therapists’ current practice of dry needling: Practice patterns and adverse events. Gattie E., Cleland J. A., Snodgrass S. 2020Musculoskelet Sci Pract. 50:102255. doi: 10.1016/j.msksp.2020.102255. [DOI] [PubMed] [Google Scholar]
- Evidence for dry needling in the management of myofascial trigger points associated with low back pain: A systematic review and meta-analysis. Liu L., Huang Q. M., Liu Q. G.., et al. 2018Arch Phys Med Rehabil. 99(1):144–152.e2. doi: 10.1016/j.apmr.2017.06.008. [DOI] [PubMed] [Google Scholar]
- The effectiveness of dry needling in patients with chronic low back pain: a prospective, randomized, single-blinded study. Rajfur J., Rajfur K., Kosowski Ł.., et al. 2022Sci Rep. 12(1):15803. doi: 10.1038/s41598-022-19980-1. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Is dry needling effective for low back pain?: A systematic review and PRISMA-compliant meta-analysis. Hu H. T., Gao H., Ma R. J., Zhao X. F., Tian H. F., Li L. 2018Medicine. 97(26):e11225. doi: 10.1097/MD.0000000000011225. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Efficacy of dry needling for chronic low back pain: A systematic review and meta-analysis of randomized controlled trials. Lara-Palomo C., Gil-Martínez I., Lopez-Fernandez D., Gonzalez G., De Los Ángeles Querol-Zaldívar L. M., Castro-Sanchez M. 2023Altern Ther Health Med. 29(8) [PubMed] [Google Scholar]
- Is dry needling applied by physical therapists effective for pain in musculoskeletal conditions? A systematic review and meta-analysis. Sánchez-Infante J., Navarro-Santana M. J., Bravo-Sánchez A., Jiménez-Diaz F., Abián-Vicén J. 2021Phys Ther. 101(3) doi: 10.1093/ptj/pzab070. doi: 10.1093/ptj/pzab070. [DOI] [PubMed] [Google Scholar]
- Adverse events associated with therapeutic dry needling. Boyce D., Wempe H., Campbell C.., et al. 2020Int J Sports Phys Ther. 15(1):103–113. doi: 10.26603/ijspt20200103. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Dry needling-induced pneumothorax. Patel N., Patel M., Poustinchian B. 2019J Am Osteopath Assoc. 119(1):59–62. doi: 10.7556/jaoa.2019.009. [DOI] [PubMed] [Google Scholar]
- An acute cervical epidural hematoma as a complication of dry needling. Lee J. H., Lee H., Jo D. J. 2011Spine. 36(13):E891–E893. doi: 10.1097/BRS.0b013e3181fc1e38. [DOI] [PubMed] [Google Scholar]
- Acute spinal epidural hematoma as a complication of dry needling: A case report. Berrigan W. A., Whitehair C. L., Zorowitz R. D. 2019PM R. 11(3):313–316. doi: 10.1016/j.pmrj.2018.07.009. [DOI] [PubMed] [Google Scholar]
- A case with iatrogenic pneumothorax due to deep dry needling. Uzar T., Turkmen I., Menekse E. B., Dirican A., Ekaterina P., Ozkaya S. 2018Radiol Case Rep. 13(6):1246–1248. doi: 10.1016/j.radcr.2018.08.019. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Three cases of hemiplegia after cervical paraspinal muscle needling. Ji G. Y., Oh C. H., Choi W. S., Lee J. B. 2015Spine J. 15(3):e9–13. doi: 10.1016/j.spinee.2014.11.007. [DOI] [PubMed] [Google Scholar]
- Lack of standardization in dry needling dosage and adverse event documentation limits outcome and safety reports: a scoping review of randomized clinical trials. Kearns G. A., Brismée J. M., Riley S. P., Wang-Price S., Denninger T., Vugrin M. 2023J Man Manip Ther. 31(2):72–83. doi: 10.1080/10669817.2022.2077516. [DOI] [PMC free article] [PubMed] [Google Scholar]
- The effects of dry needling on pain relief and functional balance in patients with sub-chronic low back pain. Loizidis T., Nikodelis T., Bakas E., Kollias I. 2020J Back Musculoskelet Rehabil. 33(6):953–959. doi: 10.3233/BMR-181265. [DOI] [PubMed] [Google Scholar]
- Comparison of two angles of approach for trigger point dry needling of the lumbar multifidus in human donors (cadavers) Hannah M. C., Cope J., Palermo A., Smith W., Wacker V. 2016Man Ther. 26:160–164. doi: 10.1016/j.math.2016.08.008. [DOI] [PubMed] [Google Scholar]
- The effects of dry needling to the thoracolumbar junction multifidi on measures of regional and remote flexibility and pain sensitivity: A randomized controlled trial. Clark N. G., Hill C. J., Koppenhaver S. L., Massie T., Cleland J. A. 2021Musculoskel Sci Pract. 53:102366. doi: 10.1016/j.msksp.2021.102366. [DOI] [PubMed] [Google Scholar]
- Changes in lumbar multifidus muscle function and nociceptive sensitivity in low back pain patient responders versus non-responders after dry needling treatment. Koppenhaver S. L., Walker M. J., Su J.., et al. 2015Man Ther. 20(6):769–776. doi: 10.1016/j.math.2015.03.003. [DOI] [PubMed] [Google Scholar]
- Immediate changes in resting and contracted thickness of transversus abdominis after dry needling of lumbar multifidus in healthy participants: A randomized controlled crossover trial. Puentedura E. J., Buckingham S. J., Morton D., Montoya C., Fernandez de Las Penas C. 2017J Manip Physiol Ther. 40(8):615–623. doi: 10.1016/j.jmpt.2017.06.013. [DOI] [PubMed] [Google Scholar]
- Validity and reliability of dry needle placement in the deep lumbar multifidus muscle using ultrasound imaging: an in-vivo study. Wang-Price S. S., Etibo K. N., Short A. P., Brizzolara K. J., Zafereo J. A. 2022J Man Manip Ther. 30(5):284–291. doi: 10.1080/10669817.2022.2051239. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Baseline examination factors associated with clinical improvement after dry needling in individuals with low back pain. Koppenhaver S. L., Walker M. J., Smith R. W.., et al. 2015J Orthop Sports Phys Ther. 45(8):604–612. doi: 10.2519/jospt.2015.5801. [DOI] [PubMed] [Google Scholar]
- Short-term effects of two deep dry needling techniques on pressure pain thresholds and electromyographic amplitude of the lumbosacral multifidus in patients with low back pain - a randomized clinical trial. Wang-Price S., Zafereo J., Couch Z., Brizzolara K., Heins T., Smith L. 2020J Man Manip Ther. 28(5):254–265. doi: 10.1080/10669817.2020.1714165. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Safety considerations when dry needling the multifidi in the thoracolumbar region: A cadaveric study. Williams C. L., Falyar C. R., McConnell R. C., Lindsley S. 2023Int J Sports Phys Ther. 18(6) doi: 10.26603/001c.89663. doi: 10.26603/001c.89663. [DOI] [PMC free article] [PubMed] [Google Scholar]
- The use of trigger point dry needling and intramuscular electrical stimulation for a subject with chronic low back pain: A case report. Rainey C. E. 2013Int J Sports Phys Ther. 8(2):145–161. [PMC free article] [PubMed] [Google Scholar]
- Dry needling for the management of thoracic spine pain. Fernanfernández-De-Las-Peñas C., Layton M., Dommerholt J. 2015J Man Manip Ther. 23(3):147–153. doi: 10.1179/2042618615Y.0000000001. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Obtaining local twitch response with ultrasound-guided dry needling. Yildizgoren M. T., Bagcier F. 2023Med Ultrason. 25(3):362–363. doi: 10.11152/mu-4199. [DOI] [PubMed] [Google Scholar]
- Reliability and validity of manual palpation for the assessment of patients with low back pain: a systematic and critical review. Nolet P. S., Yu H., Côté P.., et al. 2021Chiropr Man Ther. 29(1):33. doi: 10.1186/s12998-021-00384-3. [DOI] [PMC free article] [PubMed] [Google Scholar]
- The validity of lumbo-pelvic landmark palpation by manual practitioners: A systematic review. Alexander N., Rastelli A., Webb T., Rajendran D. 2021Int J Osteopath Med. 39:10–20. doi: 10.1016/j.ijosm.2020.10.008. [DOI] [Google Scholar]
- Imaging with ultrasound in physical therapy: What is the PT’s scope of practice? A competency-based educational model and training recommendations. Whittaker J. L., Ellis R., Hodges P. W.., et al. 2019Br J Sports Med. 53(23):1447–1453. doi: 10.1136/bjsports-2018-100193. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Dry needling curricula in entry-level education programs in the United States for physical therapists. Matthews L., Ford G., Schenk R., Ross M., Donnelly J. 2021J Man Manip Ther. 29(2):83–91. doi: 10.1080/10669817.2020.1813471. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Factors associated with thickening of the ligamentum flavum on magnetic resonance imaging in patients with lumbar spinal canal stenosis. Yabe Y., Hagiwara Y., Tsuchiya M.., et al. 2022Spine. 47(14):1036–1041. doi: 10.1097/BRS.0000000000004341. [DOI] [PubMed] [Google Scholar]
- Tensile test of human lumbar ligamentum flavum: Age-related changes of stiffness. Mihara A., Nishida N., Jiang F.., et al. 2021Appl Sci. 11(8):3337. doi: 10.3390/app11083337. [DOI] [Google Scholar]
- The thickness of the ligamentum flavum in relation to age and gender. Safak A. A., Is M., Sevinc O.., et al. 2010Clin Anat. 23(1):79–83. doi: 10.1002/ca.20883. [DOI] [PubMed] [Google Scholar]
- Degenerative lumbar disc and facet disease in older adults: prevalence and clinical correlates. Hicks G. E., Morone N., Weiner D. K. 2009Spine. 34(12):1301–1306. doi: 10.1097/BRS.0b013e3181a18263. [DOI] [PMC free article] [PubMed] [Google Scholar]