J Manipulative Physiol Ther 2014 (May); 37 (4): 211–218 ~ FULL TEXT
Anneli Peolsson, PhD, Maria Landén Ludvigsson, MSc, PT, Johanna Wibault, MSc, PT, Åsa Dedering, PhD, PT, Gunnel Peterson, MSc, PT
Anneli Peolsson, Associate Professor, PhD, PT,
Department of Medical and Health Sciences,
Physiotherapy, Hälsans hus plan 12, Campus US,
Linköping University, SE-58183 Linköping, Sweden
Objective The purposes of this study were to examine whether any differences in function and health exist between patients with cervical radiculopathy (CR) due to disk disease scheduled for surgery and patients with chronic whiplash-associated disorders (WADs) and to compare measures of patients' physical function with those obtained from healthy volunteers.
Methods This is a cross-sectional study of patients with CR (n = 198) and patients with chronic WAD (n = 215). Patient data were compared with raw data previously obtained from healthy people. Physical measures included cervical active range of motion, neck muscle endurance, and hand grip strength. Self-rated measures included pain intensity (visual analog scale), neck disability (Neck Disability Index), self-efficacy (Self-Efficacy Scale), and health-related quality of life (EuroQol 5-dimensional self-classifier).
Results Patient groups exhibited significantly lower performance than the healthy group in all physical measures (P < .0005) except for neck muscle endurance in flexion for women (P > .09). There was a general trend toward worse results in the CR group than the WAD group, with significant differences in neck active range of motion, left hand strength for women, pain intensity, Neck Disability Index, EuroQol 5-dimensional self-classifier, and Self-Efficacy Scale (P < .0001).
Conclusions Patients had worse values than healthy individuals in almost all physical measures. There was a trend toward worse results for CR than WAD patients.
From the FULL TEXT Article:
Comparisons Between Patients and Healthy Participants and CR and WAD Patients
Both patient groups exhibited results that were approximately 20% to 80% of healthy volunteers' results in nearly all physical measures, suggesting the importance of physical rehabilitation aimed at gaining function. This finding was particularly pronounced for neck muscle endurance (NME) extension. The nonsignificant difference between female patients and healthy women regarding NME flexion may indicate that even healthy women have relatively low muscle endurance compared with men (P < .0001)28; this may be an important factor regarding the higher prevalence of neck pain among women than among men.  To compare the 3 groups properly, it was necessary to standardize the assessments performed in all three groups as well as the ability to use raw data.
The physical disability results confirm results from earlier small studies involving CR patients [5, 8–10] as well as earlier small studies of AROM in patients with chronic WAD. [18, 19] Mean values of neck AROM data for the CR group are comparable with earlier studies of CR patients with relatively few participants [5, 9] and were lower for both patient groups than those obtained in young adults being treated for radiating neck pain.  Regarding hand strength, CR patients in the present study fared worse than in earlier studies, and WAD patients exhibited results similar to those of CR patients in previous studies. [5, 9] The lower hand strength among CR patients in the present study may be explained by more generous inclusion criteria for surgery in studies that were initiated more than a decade ago but may also be a reflection of the small study samples in the older studies. [5, 9] Neck muscle endurance flexion values in the present WAD patients were comparable with those of previous nonspecific neck pain patients ; however, the NME extension values among the present female WAD patients were worse.  The NME values for CR patients in the present study were both slightly better and worse than reported in earlier studies of CR patients. [5, 8, 9]
All measurements were worse for the CR group; to our knowledge, no such comparison between the groups has been presented before.
Whiplash-Associated Disorder Grade
Whiplash-associated disorder grade was important regarding both physical measures and self-reported data; although this finding was not unexpected, it was debatable. [24, 25] To our knowledge, only 1 previous randomized controlled trial  of patients with chronic WAD included Grade III patients. The results of the present study show that there is an urgent need for increased knowledge of the best way to treat this subgroup of WAD patients, suggesting that future randomized controlled trials should also include patients with Grade III WAD.
Correlation Between Measures
Although significant, the correlations between the physical measures and the self-reported pain, function, and health data were relatively low, indicating that physical rehabilitation must be combined with treatments that aim to improve other important factors, such as psychosocial factors. Psychosocial factors have shown to be important predictors of treatment outcome in both CR and WAD patients. [16, 36, 37] Apart from neck-specific exercises, [38, 39] cognitive behavioral intervention has been suggested to be effective in neck pain patients. [18, 40] Health-related quality of life measurements with EQ-5D were worse in both groups of patients in the present study than among previous patients with, for example, low back pain and asthma,  demonstrating the frailty that can follow neck pain problems and the interference of such problems with patients' daily lives. The low EQ-5D value for CR patients of only 0.39 is noteworthy. The SES results in the present study are in agreement with the previous results of patients with subacute WAD ; however, to our knowledge, such results in patients with MRI-verified CR scheduled for surgery have never been presented before. Although the CR patients were scheduled for surgery, surgery cannot be expected to solve more than the segmental dysfunction and factors related to nerve encroachment in the particular segmental area. Additional studies about the role of physiotherapy in preoperative and postoperative neck surgery are, therefore, needed in light of the results of the present study and owing to the lack of NDI improvement reported in a long-term follow-up study of the effects of surgery. 
One limitation of the present study is the difference in sex distribution between the 2 patient groups: the CR patient group was 47% women and the WAD patient group was 64% women. This variation was expected from other studies [1, 44] and can be considered representative for each group. Especially when measuring hand strength and NME, biological sex has been shown to be important to consider when interpreting the results. [27, 28] Women with chronic pain also tend to give up physical activity to a greater extent than men,  which can further influence the physical measures. To be able to compare these patient groups with healthy volunteers and to limit the effect of different levels of representation, hand strength and NME were stratified by biological sex in the analysis. Alternative analysis was also performed for the other variables, leading to a nonsignificant difference between CR and WAD for men in the transverse plane, but no other changes in the results (Table 1). Nevertheless, sex distribution may influence the results of the present study. Despite this possibility, the present study demonstrated worse results for CR patients than WAD patients. If the sex distribution had been equal, there may had been an even greater difference between the groups, as female sex has been shown correlate with worse outcome. [36, 37, 46] We, therefore, argue that a more equal sex distribution would not alter the conclusions of the study.
For security reasons and owing to the risk of confounding factors, CR patients with myelopathy and WAD patients with head injuries were excluded. Therefore, the results may underestimate the severity of problems in these patient groups overall. Nevertheless, our findings undoubtedly demonstrate the existence of disability in these patient groups compared with a healthy population as well as the potential for treatment to be improved.
In the present study, ventral and dorsal NME was investigated as a result of united neck muscle performance. However, for a deeper understanding of muscle function, the coordination between different muscle layers needs to be examined in future studies. 
The present study reported patients to have low physical function and high disability in the investigated measures that also were related to self-evaluated function and health, showing the potential of training these functions in rehabilitation and especially for those patients with neurologic deficits.
Both WAD and CR patients generally exhibited worse results than healthy volunteers. Patients with CR appeared to be worse than the WAD group. Patients with Grade III WAD exhibited worse results than those with Grade II WAD. Further studies are needed to investigate whether training of neck function aiming to improve AROM and NME may improve outcome in these patients.