Macaque Model of Carpal Tunnel Syndrome: Effects of Force and Posture Exposures

Details

• Personal Author:
  Buford J ; Lavender S ; Pease W ; Sommerich CM
• Description:
  "The role of overuse of the hand...in causation of carpal tunnel syndrome (CTS) remains controversial..." (Bland, 2005). Many epidemiological studies have been conducted to determine if CTS is a work-related disorder, and if so, what risk factors contribute to its development. Evidence exists for and against CTS as a work-related disorder, in particular, because there are several non-occupational risk factors associated with CTS. Animal models offer several advantages in the study of CTS, including ability to directly explore physical exposure and health outcomes as they develop over time. Another is elimination or control of many personal factors associated with CTS, Our preliminary research, employing our unique animal model of CTS, demonstrated a causal connection between exposure to moderately forceful, repetitive manual work and development of median mononeuropathy at the wrist (analogous to CTS in humans) (Sommerich et al., 2007). Our results further substantiated the pattern of evidence provided through prior epidemiological and laboratory-based studies. In the current study we proposed to investigate outcomes from exposure to different levels of two risk factors (posture and force) identified in epidemiological or laboratory research as important or biomechanically-relevant to development of CTS in humans (Phase 1: aims 1 and 2), and to expand our database of maximum voluntary pinch force of macaques (Phase 2: aim 3), the latter is relevant to setting experimental force levels (as % of maximum). In Phase 1, twenty-four macaques performed a repetitive, slightly or moderately forceful pinch task for food rewards for 18 weeks. They performed the task in one of three work postures: wrist flexion, neutral, or extension. Nerve conduction velocity (NCV) was the primary dependent measure. Key findings: 1) a declining trend in NCV was observed in two-thirds of the animals, 2) only animals who worked in flexion developed a pronounced and protracted decline in NCV, 3) only a small percentage (3 of 17) animals who worked at a force level near or above 20% of their predicted maximum showed no evidence of decline in NCV, 4) a moderate association (correlation) was found across subjects between decline in NCV and repetition, 5) moderate to strong associations were found between NCV and pinch force, repetition, and work measure variables for animals that showed extended declines in NCV. In Phase 2, strength data were obtained from 17 subjects, using a custom-designed apparatus built to assess maximal pinch force in neutral, flexed, and extended wrist postures. Key findings: 1) pinch strength declined from neutral to flexed to extended postures, 2) correlations were strongest between wrist circumference and peak pinch strength for neutral and extended postures, 3) in flexed posture, body mass showed a stronger correlation with pinch strength than did wrist circumference. Overall, study results are consistent with findings from our previous study and other animal models that demonstrate that moderately forceful, repetitive use of the end effector of the upper extremity can have detrimental effects on elements of the musculoskeletal system, including the median nerve, which supports the concept of CTS as a work-related disorder in some workers. [Description provided by NIOSH]
• Subjects:
  Animals Musculoskeletal Diseases Musculoskeletal System Occupational Health Risk Assessment Risk Factors Safety
• Keywords:
  Animal Studies Carpal Tunnel Syndrome CTS MSD Musculoskeletal Disorders Posture Repetitive Work Risk Factors Upper Extremities
• Series:
  Grant Final Reports
• Publisher:
  National Institute for Occupational Safety and Health
• Document Type:
  Text
• Funding:
  Grant
• Genre:
  Final Grant Report
• Place as Subject:
  Ohio ; OSHA Region 5
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Division:
  OEP - Office of Extramural Programs
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Pages in Document:
  1-28
• NIOSHTIC Number:
  nn:20059185
• NTIS Accession Number:
  PB2022-100315
• Citation:
  Atlanta, GA: U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, R01-OH-009131, 2012 Dec; :1-28
• Contact Point Address:
  Carolyn M. Sommerich, PhD, The Ohio State University, Department of Integrated Systems Engineering, 1971 Neil Ave., Columbus, OH 43210
• Email:
  sommerich.1@osu.edu
• Federal Fiscal Year:
  2013
• NORA Priority Area:
  Services
• Performing Organization:
  Ohio State University
• Peer Reviewed:
  False
• Start Date:
  20080801
• Source Full Name:
  National Institute for Occupational Safety and Health
• End Date:
  20120731
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:be278ae7f9fa1583404e8969f56104616d722544e04698bd62b1ee735fb42eb1cb80019aa60f9f137a8bef720247a74db26471856e8110068a53c5fbc06979e8
• Download URL:
  https://stacks.cdc.gov/view/cdc/218970/cdc_218970_DS1.pdf
• File Type:
  [PDF - 1.32 MB ]