Research Review Corner: September 2012

Neck Muscle Strength and Mobility of the Cervical Spine as Predictors of Neck Pain – A Prospective Six-year Study

BACKGROUND INFORMATION
It is well known that neck pain is common and costly, resulting in considerable medical service consumption, disability and work absenteeism. When dealing with cervical spine pain in clinical practice, we often use simple measures such as spinal range of motion (ROM) and muscle strength for both assessment/diagnostic and outcome purposes. Some even use them as screening procedures on healthy patients in an attempt to identify those at risk for developing neck pain. Is this an evidence-informed approach?

Although the clinical importance of ROM is still controversial, there is evidence that those with neck pain tend to have weaker neck muscles than subjects without neck pain,1 suggesting that reduced neck strength could be a contributing factor in neck pain. To further support the relationship between neck pain and neck strength, the use of simple neck strengthening exercises has been shown to relieve neck pain in numerous clinical trials. As a result, neck exercise is now a front-line treatment recommended for neck pain patients.2

Overall, we are still unsure of the predictive value of reduced neck strength and mobility (ROM). The question is, do those with weaker necks and reduced cervical ROM stand a higher chance of experiencing future neck pain? The aim of this study was to determine whether neck muscle strength and/or passive mobility among pain-free, working-aged women could predict future episodes of neck pain.

CONCLUSIONS AND PRACTICAL APPLICATIONS
A recent literature review concluded that physical capacity and measures such as ROM and muscle strength or endurance were poor predictors of both future low back pain and neck pain.3 More specifically, the authors of that particular review found strong evidence that there is no relationship between the endurance of trunk musculature and the risk of low back pain. However, they did report inconclusive evidence for a relationship between trunk muscle strength, or lumbar spine mobility, and the risk of low back pain – more work is needed in this area. Due to a limited number of studies, inconclusive evidence for a relationship between physical capacity measures and a risk for neck or shoulder pain was reported. The authors of the literature review appropriately mentioned the heterogeneity of the literature overall, mandating caution when interpreting their conclusions.3

This study adds information regarding a relationship between physical capacity measures and future neck pain, suggesting that neck pain cannot be predicted by isometric neck muscle strength or passive ROM measurements in healthy female subjects. This should remind us that neck pain is a multifactorial condition, and that we should always consider not only the physical capacity of the individual as a potential risk factor, but also work-related physical and psychosocial risk factors, which have been shown to be potential predictors for future neck pain. At this time, it is not advisable to utilize cervical ROM and strength as screening tools to predict future neck pain. As always, further research is required on larger samples as well as on men.

Lastly, the “chicken and egg” argument regarding the relationship between neck pain and reduced cervical muscle strength remains unsolved.

In addition to practising full time in Toronto, Dr. Shawn Thistle is founder and president of Research Review Service Inc., an online, subscription-based service designed to help busy practitioners integrate current, relevant scientific evidence into their practice (www.researchreviewservice.com ). Shawn also recently launched The Epicurean Scholar, which offers continuing education seminars combined with gourmet food and wine events (www.epicureanscholar.com ).  Dr. Thistle graduated from CMCC (where he lectures in the Orthopedics Department) and holds an Honours Degree in Kinesiology from McMaster University. He also holds a certificate in Contemporary Medical Acupuncture from McMaster University, and is a Certified Active Release Techniques (ART®) Provider and Functional Range Release®/Functional Anatomical Palpation® instructor and provider.