Our addiction to gadgets is putting undue stresses on the cervical spine, writes Kenneth K Hansraj, New York, USA. He wrote for Spinal News International following the publication of his study, “Assessment of stresses in the cervical spine caused by posture and position of the head”, which made waves worldwide.
When our study was released, almost every news outlet globally picked it up. According to a Cision report, the study was viewed worldwide by 3.3 billion people (from 16–27 November 2014) with coverage from news services including CBS, NBC, ABC, FOX, CNN and the Today Show. My team believes that the final view count will be circa 4 billion, with an additional great deal of interest in the study in the Middle East and China since the Cision survey was conducted.
Evidently, the study is of significant interest to the billions of people using mobile phone devices worldwide, many of whom are doing so with poor posture. The purpose of our study was to assess the forces incrementally seen by the cervical spine as the head is tilted forward into a worsening posture. We also wanted to help cervical spine surgeons understand the consequences of this kind of damage in regards to the reconstruction of the neck.
Spine care physicians are reporting more and more observations of poor posture-mediated neck and back pain suffering in their patients. I believe that, given the vast use of smart devices in poor posture, posture-induced neck and back pain will become increasingly prevalent in spine care offices all over the world.
People spend an average of two to four hours a day with their heads tilted, reading and texting on their smart phones and mobile devices. Cumulatively this is 700–1,400 hours a year of excess stresses on the cervical spine. Take, for example, a teenager with their head down at 60 degrees with 60 pounds of force. They could spend 5,000 hours in this position in high school alone, resulting in 300,000 pounds of force in four years. This is a worst-case scenario, but even one half of this assessment is still too much and could cause lasting damage.
To gather our data, a model of the cervical spine was created with realistic values in COSOMOSWorks (SolidWorks), a finite element assessment package. Calculations were made and forces were extracted in newtons and converted into pounds. We made the calculations using neck + head, which gave an average weight of 60 newtons (6kg or 13.2 pounds). The centre of mass was located 16cm above C7, or 15cm from the top of the skull.
The weight taken by the spine dramatically increases when flexing the head forward at varying degrees. An adult head weighs 10–12 pounds in the neutral position. As the head tilts forward, the load on the neck surges to 27 pounds at 15 degrees, 40 pounds at 30 degrees, 49 pounds at 45 degrees and 60 pounds at 60 degrees. At 90 degrees the model prediction was not reliable.
Loss of the natural curve of the cervical spine leads to incrementally increased stresses on the cervical spine. The first to be affected are the ligaments. For example, when the posterior atlanto-axial ligament is stressed with flexion it becomes inflamed. With inflammation at C1 and C2 there is loss of side-by-side range of motion resulting in stiffness as the muscles become stressed and inflamed. Stressing a muscle makes it stronger, but persistent eccentric loading leads to intractable pain. The disc spaces are also eccentrically loaded and suffer undue stresses. With persistent eccentric loading, the process of wear, tear, and degeneration proceeds.
Physicians, patients and industry are becoming aware of this problem, and developments to help users maintain healthy posture are fast becoming more common. For example, Dean Fishman of the Text Neck Institute has created a mobile app to help users avoid incorrect head posture. When your phone is held at a safe viewing angle, a green light shines in the top left corner. When you are at risk for “text neck”, a red light appears. Additional vibrations or beeps can be added as further warnings.
Such problems with the cervical spine are avoidable. While it is nearly impossible to avoid the technologies that cause these issues, individuals should make an effort to look at their phones with a neutral spine and avoid spending many hours each day hunched over their gadgets.
How to avoid cervical spine damage when using mobile technology:
- Utilise good posture.
- Bring your ears above your shoulders.
- Open up your chest by retracting the scapulae.
- Keep your head up.
- Raise the device up and look down with your eyes.
- Maintain your natural spinal alignment.
Kenneth K Hansraj is chief of spine surgery at New York Spine Surgery and Rehabilitation Medicine, New York, USA