Monday 10 July 2017

When do biomechanics matter?

Anyone who has followed the evidence in health & fitness over the last 3-5 years has likely seen a rise in the popularity of pain science. The rise in popularity of pain science has also created a decline in the popularity of biomechanics as well as a bit of backlash against the biomechanics industry. While biomechanics aren’t as relevant to pain (particularly chronic pain) as some may think there still are certain situations where biomechanics matter.

Before I get this article rolling there are a couple things I have to mention first

1) I would be remised if I didn’t mention my fellow Canuck Greg Lehman for the great work that he’s done discussing when biomechanics do and don’t matter in pain & injury. Look at his website, his appearances on The Physio Matters Podcast and his presentation from the San Diego Pain Summit.  

2) For the sake of keeping this article short and not bogged down in references I don’t have every single article on biomechanics and pain/injury cited in this blog.

With that out of the way here is when biomechanics do and don’t matter…

We know from the scientific literature that certain biomechanical movement variables can be risk factors and/or mechanisms of certain injuries such as

-          Loaded spine flexion and disc injury1
-          Dynamic knee valgus & ACL tears2, PFPS3, patellar dislocations4 and MCL tears5
-          Various FOOSH (fall on outstretched hand) injuries such as scaphoid fractures6 and AC joint separations7
-          Ankle inversion & eversion sprains8,9
-          Shoulder (and hip) abduction & external rotation and dislocations10,11
-          Prolonged postures and musculoskeletal pain12,13

The things you have to keep in mind when looking at biomechanics are ...

1) A lot of biomechanical variables that people cite in their assessments & clinical reasoning models either can’t be reliably assessed and/or don’t correlate well with pain including

-          Resting scapular position14–17
-          Resting lumbar lordosis, cervical lordosis, thoracic kyphosis, and sacral angle18–25

2) Injury doesn’t always equal pain. We have lots of examples in the literature of people who have degenerated/bulging discs26, arthritis27, and partial rotator cuff tears28 yet they don’t have pain. Conversely many people can also have pain without injury.

3) We know in the literature that psychosocial factors can play a huge role in pain, particularly in chronic pain29,30.

4) The body can adapt to load and stress assuming that the stress is applied and progressed appropriately based on the status & demands of the individual31.

5) The amount of load/speed during a specific movement pattern is important. Many of the examples of biomechanical injury mechanisms above apply to high speed and/or high load activities. Obviously you don't have as much "movement leniency" deadlifting 700 lbs as you would bending over to pick up change. Ask any top level powerlifter where top level athletes squat 1000+ lbs and bench press 500-800+ lbs (depending on equipped or not) and they will tell you that there isn’t much margin for error with technique.

6) Our words can be more powerful than we think and when used incorrectly can create a nocebo effect (the opposite of placebo effect)32. When coaching movements & exercises it’s essential to use positive coaching & cueing for exercise & movement techniques to prevent kinesiophobia and fear avoidance. It's also important to instill positive beliefs in clients about their bodies.

So as you can see, biomechanical variables are still relevant to health & fitness professionals but they need to be looked at in light of both true biomechanical evidence (not just speculation) and the biopsychosocial model of pain.

To summarize the points in this article
1) Some biomechanical movement patterns can be mechanisms of (and risk factors for) injury
2) Many “biomechanical” variables can’t be reliably assessed and/or don’t correlate with pain
3) Injury doesn’t always equal pain. Psychosocial factors can play a huge role in pain.
4) Tissues can adapt to appropriately applied load.
5) Biomechanics and movement patterns apply more during high load & high speed situations than during low load situations.
6) When coaching & cueing movements & exercises use positive coaching to prevent nocebo effects and maximize your clients’ confidence in their bodies.

1.           McGill SM. Low Back Disorders: The Scientific Foundation for Prevention and Rehabilitation. Champaign, IL: Human Kinetics; 2002.
2.           Hewett TE, Bates NA. Preventive Biomechanics. Am J Sports Med. February 2017:36354651668608. doi:10.1177/0363546516686080.
3.           Weiss K, Whatman C. Biomechanics Associated with Patellofemoral Pain and ACL Injuries in Sports. Sport Med. 2015;45(9):1325-1337. doi:10.1007/s40279-015-0353-4.
4.           Duthon VB. Acute traumatic patellar dislocation. Orthop Traumatol Surg Res. 2015;101(1 Suppl):S59-67. doi:10.1016/j.otsr.2014.12.001.
5.           Indelicato. Isolated Medial Collateral Ligament Injuries in the Knee. J Am Acad Orthop Surg. 1995;3(1):9-14. Accessed July 7, 2017.
6.           Haisman JM, Rohde RS, Weiland AJ, American Academy of Orthopaedic Surgeons. Acute fractures of the scaphoid. J Bone Joint Surg Am. 2006;88(12):2750-2758. Accessed July 7, 2017.
7.           Bontempo NA, Mazzocca AD. Biomechanics and treatment of acromioclavicular and sternoclavicular joint injuries. Br J Sports Med. 2010;44(5):361-369. doi:10.1136/bjsm.2009.059295.
8.           Bennett WF. Lateral ankle sprains. Part I: Anatomy, biomechanics, diagnosis, and natural history. Orthop Rev. 1994;23(5):381-387. Accessed July 7, 2017.
9.           Hintermann B, Knupp M, Pagenstert GI. Deltoid Ligament Injuries: Diagnosis and Management. Foot Ankle Clin. 2006;11(3):625-637. doi:10.1016/j.fcl.2006.08.001.
10.         Bankart ASB. The pathology and treatment of recurrent dislocation of the shoulder-joint. Br J Surg. 1938;26(101):23-29. doi:10.1002/bjs.18002610104.
11.         Sanders S, Tejwani N, Egol KA. Traumatic hip dislocation--a review. Bull NYU Hosp Jt Dis. 2010;68(2):91-96. Accessed July 7, 2017.
12.         Briggs AM, Smith AJ, Straker LM, Bragge P. Thoracic spine pain in the general population: Prevalence, incidence and associated factors in children, adolescents and adults. A systematic review. BMC Musculoskelet Disord. 2009;10(1):77. doi:10.1186/1471-2474-10-77.
13.         Meziat Filho N, Coutinho ES, Azevedo e Silva G. Association between home posture habits and low back pain in high school adolescents. Eur Spine J. 2015;24(3):425-433. doi:10.1007/s00586-014-3571-9.
14.         Odom CJ, Taylor AB, Hurd CE, Denegar CR. Measurement of scapular asymetry and assessment of shoulder dysfunction using the Lateral Scapular Slide Test: a reliability and validity study. Phys Ther. 2001;81(2):799-809. Accessed July 8, 2017.
15.         Struyf F, Nijs J, Meeus M, et al. Does Scapular Positioning Predict Shoulder Pain in Recreational Overhead Athletes? Int J Sports Med. 2013;35(1):75-82. doi:10.1055/s-0033-1343409.
16.         Struyf F, Nijs J, De Graeve J, Mottram S, Meeusen R. Scapular positioning in overhead athletes with and without shoulder pain: a case-control study. Scand J Med Sci Sports. 2011;21(6):809-818. doi:10.1111/j.1600-0838.2010.01115.x.
17.         Lewis JS, Green A, Wright C, Kennedy J, Kennedy R. Subacromial impingement syndrome: the role of posture and muscle imbalance. J Shoulder Elb Surg. 1990;14(4):385-392. doi:10.1016/j.jse.2004.08.007.
18.         Grob D, Frauenfelder H, Mannion AF. The association between cervical spine curvature and neck pain. Eur Spine J. 2007;16(5):669-678. doi:10.1007/s00586-006-0254-1.
19.         Tüzün C, Yorulmaz I, Cindaş A, Vatan S. Low back pain and posture. Clin Rheumatol. 1999;18(4):308-312. Accessed July 8, 2017.
20.         Nourbakhsh MR, Arab AM. Relationship Between Mechanical Factors and Incidence of Low Back Pain. J Orthop Sport Phys Ther. 2002;32(9):447-460. doi:10.2519/jospt.2002.32.9.447.
21.         Schroeder J, Schaar H, Mattes K. Spinal alignment in low back pain patients and age-related side effects: a multivariate cross-sectional analysis of video rasterstereography back shape reconstruction data. Eur Spine J. 2013;22(9):1979-1985. doi:10.1007/s00586-013-2787-4.
22.         Laird RA, Gilbert J, Kent P, Keating JL. Comparing lumbo-pelvic kinematics in people with and without back pain: a systematic review and meta-analysis. BMC Musculoskelet Disord. 2014;15(1):229. doi:10.1186/1471-2474-15-229.
23.         Christensen ST, Hartvigsen J. Spinal Curves and Health: A Systematic Critical Review of the Epidemiological Literature Dealing With Associations Between Sagittal Spinal Curves and Health. J Manipulative Physiol Ther. 2008;31(9):690-714. doi:10.1016/j.jmpt.2008.10.004.
24.         Nakipoğlu GF, Karagöz A, Ozgirgin N. The biomechanics of the lumbosacral region in acute and chronic low back pain patients. Pain Physician. 11(4):505-511. Accessed July 8, 2017.
25.         Mitchell T, O’Sullivan PB, Burnett AF, Straker L, Smith A. Regional differences in lumbar spinal posture and the influence of low back pain. BMC Musculoskelet Disord. 2008;9(1):152. doi:10.1186/1471-2474-9-152.
26.         Brinjikji W, Luetmer PH, Comstock B, et al. Systematic literature review of imaging features of spinal degeneration in asymptomatic populations. AJNR Am J Neuroradiol. 2015;36(4):811-816. doi:10.3174/ajnr.A4173.
27.         Bedson J, Croft PR. The discordance between clinical and radiographic knee osteoarthritis: A systematic search and summary of the literature. BMC Musculoskelet Disord. 2008;9(1):116. doi:10.1186/1471-2474-9-116.
28.         Sher JS, Uribe JW, Posada A, Murphy BJ, Zlatkin MB. Abnormal findings on magnetic resonance images of asymptomatic shoulders. J Bone Joint Surg Am. 1995;77(1):10-15. Accessed June 30, 2017.
29.         Innes SI. Psychosocial factors and their role in chronic pain: A brief review of development and current status. Chiropr Osteopat. 2005;13(1):6. doi:10.1186/1746-1340-13-6.
30.         Edwards RR, Dworkin RH, Sullivan MD, Turk DC, Wasan AD. The Role of Psychosocial Processes in the Development and Maintenance of Chronic Pain. J Pain. 2016;17(9):T70-T92. doi:10.1016/j.jpain.2016.01.001.
31.         Belavý DL, Quittner MJ, Ridgers N, Ling Y, Connell D, Rantalainen T. Running exercise strengthens the intervertebral disc. Sci Rep. 2017;7:45975. doi:10.1038/srep45975.

32.         Petersen GL, Finnerup NB, Colloca L, et al. The magnitude of nocebo effects in pain: A meta-analysis. Pain. 2014;155(8):1426-1434. doi:10.1016/j.pain.2014.04.016.

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