eO
RIGINAL
ARTICLE
The Association Between Cervical Spine Pathology and Rotator Cuff Dysfunction Alan L. Zhang, MD, Alexander A. Theologis, MD, Bobby Tay, MD, and Brian T. Feeley, MD
Study Design: Retrospective cohort study. Objective: To investigate the relationship between cervical spine (C-spine) and rotator cuff (RTC) pathology. Summary of Background Data: Cervical spine and RTC pathology cause significant shoulder pain in isolation and in tandem, but there is limited information about the relationship between these 2 entities. Methods: Patients with a diagnosis of C-spine and/or RTC pathology between 2005 and 2011 were identified using a large national database composed of private payer as well as Medicare patient records. Patients with concomitant C-spine and RTC diagnoses were then stratified by age group and sex. Patients with lumbar spine (L-spine) and RTC pathology were used as a comparative group, and multivariate logistic regression was used for statistical analysis. Results: Concomitant C-spine and RTC diagnoses were identified in 86,928 patients representing 13% of 679,112 patients with a RTC diagnosis and 16% of 531,177 patients with a C-spine diagnosis. The association between C-spine and RTC pathology increased significantly with age as RTC diagnoses were present in 13% of patients with C-spine pathology younger than 60 years old but increased to 25% in C-spine patients older than 60 years (P < 0.0001). For patients over 60 years old who developed a new C-spine diagnosis, 11% would develop a new RTC diagnosis or undergo an operation for a RTC disorder within 5 years. Lumbar diagnosis codes (2,297,480 patients) were over 4 times more common than C-spine codes but RTC pathology had a significantly higher correlation with C-spine pathology than L-spine pathology (odds ratio, 2.32) and patients with C-spine pathology were more likely to develop new rotator cuff pathology (odds ratio, 1.53). Conclusions: The association between cervical spine and RTC pathology is significantly greater than that between L-spine and RTC pathology and increases substantially with patient age. Further studies are needed to elucidate the cause of this relationship.
R
otator cuff (RTC) integrity is critical for optimal shoulder girdle function. As RTC pathology is one of the most common causes of shoulder pain and affects a significant portion of the population,1–4 elucidating the fundamental pathophysiology of RTC disease has been a major scientific and clinical undertaking. Although the cause of RTC pathology is multifactorial, it is evident that the integrity of the muscles’ peripheral innervation is essential for maintenance of each muscle’s quality and function.5–13 This is exemplified by the suprascapular nerve, which if damaged results in deterioration of the supraspinatus muscle (ie, muscle atrophy, fatty infiltration).6–12 More proximal compromise or injury of the nerve at the level of the cervical nerve roots could be expected to result in a similar phenomenon; however, this association is not well defined.1,7,12–14 Anatomically, the RTC is innervated by the suprascapular, axillary, and upper and lower subscapular nerves, all of which derive from the fifth (C5) and sixth (C6) cervical nerve roots. Clinically, a C5 radiculopathy may be difficult to distinguish from RTC disease, as both can manifest as shoulder pain and weakness, particularly abduction and external rotation. Similarly, a C6 radiculopathy (the second most common cervical radiculopathy) presents with shoulder pain and weakness, although it may also manifest with distal extremity symptoms. As both the prevalence of cervical spine and RTC disease increase with age,4,15–22 accurate distinction between the 2 pathologic states is often challenging for shoulder and spine surgeons. To our knowledge, there has not been any evaluation of the association between cervical spine (C-spine) pathology and RTC dysfunction in a cohort sufficiently powered to elucidate this relationship. The purpose of this study was to evaluate the correlation between RTC disease and cervical spine pathology using a large national insurance claims database. We hypothesize that there is a significant correlation between rotator RTC pathology and cervical spine pathology.
Key Words: cervical spine, rotator cuff, shoulder and spine, association (J Spinal Disord Tech 2015;28:E206–E211) Received for publication October 6, 2014; accepted October 30, 2014. From the Department of Orthopaedic Surgery, University of California— San Francisco, San Francisco, CA. The authors declare no conflict of interest. Reprints: Alan L. Zhang, MD, Department of Orthopaedic Surgery, University of California—San Francisco, 1500 Owens St. Box 3004, San Francisco, CA 94158 (e-mail: [email protected]). Copyright r 2014 Wolters Kluwer Health, Inc. All rights reserved.
E206 | www.jspinaldisorders.com
METHODS Study Sample The Pearldiver Patient Record Database (http:// www.pearldiverinc.com; Pearldiver Inc., Fort Wayne, IN) was analyzed for this study. This is a publicly available, Health Insurance Portability and Accountability Act (HIPAA), compliant national database compiled through record collections from multiple private payer insurance agencies, the largest contribution of which is from the J Spinal Disord Tech
Volume 28, Number 4, May 2015
J Spinal Disord Tech
Volume 28, Number 4, May 2015
Shoulder and Spine Association
UnitedHealth Group (http://www.unitedhealthgroup. com; UnitedHealth Group Inc., Minnetonka, MN), as well as Medicare claims data.23,24 It currently contains over 92 million patient records with an orthopaedic International Classification of Diseases, Ninth Revision (ICD-9) or Current Procedural Terminology (CPT) code. As it is a deidentified source, this study was exempt from review by the institutional review board. The database was used to separately query for patients between 2005 and 2011 with an International Classification of Diseases, Ninth Revision (ICD-9) diagnosis for RTC pathology (Appendix Table A1) and cervical spine pathology (Appendix Table A2) before querying for patients with concomitant RTC and cervical spine pathology. Patients with a new ICD-9 code for a C-spine disorder were then queried to determine the number of patients who developed a new RTC diagnosis or underwent a new procedure for RTC treatment within the next 5 years. For a comparison group, patients with lumbar spine (L-spine) ICD-9 diagnoses (Appendix Table A3) were also analyzed and compared with the cervical spine group with respect to association with RTC pathology. Patients were then stratified by 10-year age groups and sex.
Statistical Analysis Multivariate logistic regression analysis and w2 analysis were used to determine statistical significance. Multivariate logistic regression was used to model for risks of concomitant cervical and RTC pathology, whereas w2 analysis was used to determine significance of distributions in each category such as age or sex. Significance was set for all analyses to a P-value
RIGINAL
ARTICLE
The Association Between Cervical Spine Pathology and Rotator Cuff Dysfunction Alan L. Zhang, MD, Alexander A. Theologis, MD, Bobby Tay, MD, and Brian T. Feeley, MD
Study Design: Retrospective cohort study. Objective: To investigate the relationship between cervical spine (C-spine) and rotator cuff (RTC) pathology. Summary of Background Data: Cervical spine and RTC pathology cause significant shoulder pain in isolation and in tandem, but there is limited information about the relationship between these 2 entities. Methods: Patients with a diagnosis of C-spine and/or RTC pathology between 2005 and 2011 were identified using a large national database composed of private payer as well as Medicare patient records. Patients with concomitant C-spine and RTC diagnoses were then stratified by age group and sex. Patients with lumbar spine (L-spine) and RTC pathology were used as a comparative group, and multivariate logistic regression was used for statistical analysis. Results: Concomitant C-spine and RTC diagnoses were identified in 86,928 patients representing 13% of 679,112 patients with a RTC diagnosis and 16% of 531,177 patients with a C-spine diagnosis. The association between C-spine and RTC pathology increased significantly with age as RTC diagnoses were present in 13% of patients with C-spine pathology younger than 60 years old but increased to 25% in C-spine patients older than 60 years (P < 0.0001). For patients over 60 years old who developed a new C-spine diagnosis, 11% would develop a new RTC diagnosis or undergo an operation for a RTC disorder within 5 years. Lumbar diagnosis codes (2,297,480 patients) were over 4 times more common than C-spine codes but RTC pathology had a significantly higher correlation with C-spine pathology than L-spine pathology (odds ratio, 2.32) and patients with C-spine pathology were more likely to develop new rotator cuff pathology (odds ratio, 1.53). Conclusions: The association between cervical spine and RTC pathology is significantly greater than that between L-spine and RTC pathology and increases substantially with patient age. Further studies are needed to elucidate the cause of this relationship.
R
otator cuff (RTC) integrity is critical for optimal shoulder girdle function. As RTC pathology is one of the most common causes of shoulder pain and affects a significant portion of the population,1–4 elucidating the fundamental pathophysiology of RTC disease has been a major scientific and clinical undertaking. Although the cause of RTC pathology is multifactorial, it is evident that the integrity of the muscles’ peripheral innervation is essential for maintenance of each muscle’s quality and function.5–13 This is exemplified by the suprascapular nerve, which if damaged results in deterioration of the supraspinatus muscle (ie, muscle atrophy, fatty infiltration).6–12 More proximal compromise or injury of the nerve at the level of the cervical nerve roots could be expected to result in a similar phenomenon; however, this association is not well defined.1,7,12–14 Anatomically, the RTC is innervated by the suprascapular, axillary, and upper and lower subscapular nerves, all of which derive from the fifth (C5) and sixth (C6) cervical nerve roots. Clinically, a C5 radiculopathy may be difficult to distinguish from RTC disease, as both can manifest as shoulder pain and weakness, particularly abduction and external rotation. Similarly, a C6 radiculopathy (the second most common cervical radiculopathy) presents with shoulder pain and weakness, although it may also manifest with distal extremity symptoms. As both the prevalence of cervical spine and RTC disease increase with age,4,15–22 accurate distinction between the 2 pathologic states is often challenging for shoulder and spine surgeons. To our knowledge, there has not been any evaluation of the association between cervical spine (C-spine) pathology and RTC dysfunction in a cohort sufficiently powered to elucidate this relationship. The purpose of this study was to evaluate the correlation between RTC disease and cervical spine pathology using a large national insurance claims database. We hypothesize that there is a significant correlation between rotator RTC pathology and cervical spine pathology.
Key Words: cervical spine, rotator cuff, shoulder and spine, association (J Spinal Disord Tech 2015;28:E206–E211) Received for publication October 6, 2014; accepted October 30, 2014. From the Department of Orthopaedic Surgery, University of California— San Francisco, San Francisco, CA. The authors declare no conflict of interest. Reprints: Alan L. Zhang, MD, Department of Orthopaedic Surgery, University of California—San Francisco, 1500 Owens St. Box 3004, San Francisco, CA 94158 (e-mail: [email protected]). Copyright r 2014 Wolters Kluwer Health, Inc. All rights reserved.
E206 | www.jspinaldisorders.com
METHODS Study Sample The Pearldiver Patient Record Database (http:// www.pearldiverinc.com; Pearldiver Inc., Fort Wayne, IN) was analyzed for this study. This is a publicly available, Health Insurance Portability and Accountability Act (HIPAA), compliant national database compiled through record collections from multiple private payer insurance agencies, the largest contribution of which is from the J Spinal Disord Tech
Volume 28, Number 4, May 2015
J Spinal Disord Tech
Volume 28, Number 4, May 2015
Shoulder and Spine Association
UnitedHealth Group (http://www.unitedhealthgroup. com; UnitedHealth Group Inc., Minnetonka, MN), as well as Medicare claims data.23,24 It currently contains over 92 million patient records with an orthopaedic International Classification of Diseases, Ninth Revision (ICD-9) or Current Procedural Terminology (CPT) code. As it is a deidentified source, this study was exempt from review by the institutional review board. The database was used to separately query for patients between 2005 and 2011 with an International Classification of Diseases, Ninth Revision (ICD-9) diagnosis for RTC pathology (Appendix Table A1) and cervical spine pathology (Appendix Table A2) before querying for patients with concomitant RTC and cervical spine pathology. Patients with a new ICD-9 code for a C-spine disorder were then queried to determine the number of patients who developed a new RTC diagnosis or underwent a new procedure for RTC treatment within the next 5 years. For a comparison group, patients with lumbar spine (L-spine) ICD-9 diagnoses (Appendix Table A3) were also analyzed and compared with the cervical spine group with respect to association with RTC pathology. Patients were then stratified by 10-year age groups and sex.
Statistical Analysis Multivariate logistic regression analysis and w2 analysis were used to determine statistical significance. Multivariate logistic regression was used to model for risks of concomitant cervical and RTC pathology, whereas w2 analysis was used to determine significance of distributions in each category such as age or sex. Significance was set for all analyses to a P-value
