The Appeal CommissionThe Workers Compensation Act of Manitoba

Background:

In his application for compensation benefits, the worker contended that the condition in his left wrist, finger and elbow was related to his work duties that consisted mainly of typing. The worker explained that he worked with two computer systems and that each had its own keyboard. At both desks, the mouse is on the right side. On one computer, the mouse sits above the keyboard and on the other computer, the mouse sits at the keyboard. Neither work stations had been ergonomically assessed. He used the same chair as the computers were side by side in an L shape. When he moved from computer to computer, he rotated 90 degrees left and moves two feet in his chair. The keyboards are near the edge of the roll out shelf. He is on the computer 80% of the day. The worker described the symptoms he experienced in his left elbow and the loss of sensation in his left middle/ring finger. Over the last year, the tingling sensation migrated to the palm of his left hand. The worker stated he has been doing his current job for about 3 years and has been in management for 32 years. The worker noted that when he underwent nerve conduction studies he was told that he had deterioration in his right wrist as well.

In speaking with an adjudicator on July 26, 2006, the worker said his symptoms started two to three years earlier. He has high blood pressure which was diagnosed about four years ago. The worker said he spent 3 hours per 8 hour day on the computers. The longest duration of constant use would be approximately an hour at a time on one of the computers but this did not happen every day. The rest of the use is intermittent throughout the day and would involve use of either computer. The worker used his right hand to operate the mouse and numeric keypad. He used the “DCS” computer system 3 times a day to monitor the plant. There were 106 screens to review. He changes screens using the F keys (1-12). He uses his left hand to push the F keys. His wrists are at a 45 degree angles when typing. The keyboard tray has approximately 23 degrees tilt and the keyboard which has its legs up is at an approximate 22 degree tilt.

The results of nerve conduction studies dated May 19, 2006 showed severe left and moderately severe right CTS.

On October 20, 2006, the worker provided the WCB with additional information to support that his left CTS condition was a work related injury. This information pertained to the usage of a Bailey QNX Operating System with mylar keyboards from 1992 up until year 2001 which he thought had contributed to his “white hand condition”. He stated, “The Bailey Distributed Control System (DCS) Mylar Keyboards used in zinc Pressure Leach 1992 – 2001 were the OIS MKM keyboard. The MKM keyboard is a flat, membrane sealed keyboard. In my letter to you dated 2006.10.10, I used the word “mylar” to describe the covering – membrane sealed is a better description, as stated by the enclosed Bailey literature, from their Manual Bailey infi 90 E97-801-2 Manual…To activate any key on this robust industrial OIS MKM keyboard, the operator is required to exercise considerable downward fingertip pressure for key activation. The keypad contacts were tiny and dimpled, and needed to be struck firmly, basically in a downward orientation, to activate them. My left hand operated the keyboard, while writing down data numbers for hardcopy shift entry reports. My left hand fingers became strained at the conclusion of the 12 hour shifts…After year 2001, [employer’s] IT Department purchased “Wonderware Software” and mylar keyboards become obsolete, as the Wonderware interface allowed standard PC Compaq Computers with QWERTY keyboards. (the key here is “Interface”). Functionality, control options to “Mouse Control” was included with the Wonderware Software purchase, but mouse control came on-line later in the year. In conclusion, I have been working with computer keyboards since my transfer in 1982. Despite many computer work stations orientations I have had since 1982, up to and including the pictures the Board recently requested of my [office] in 2006, I felt that the most serious damage had occurred when working with the Bailey OIS MKM keyboards from 1992 to 2001. This is a progressive white hand style injury, with the loss of sensation in my left fingers.”

On March 9, 2007, a WCB adjudicator contacted an employer representative regarding the worker’s letter of October 20, 2006. The representative did not agree with the worker that to activate the OIS MKM keyboard, the operator is required to exercise considerable downward fingertip pressure for key activation. The keyboard was just a normal keyboard, his hands are held straight to use it, no extra fingertip pressure is used for key activation, even with the plastic cover on it. There was no repetition of force, no extension of wrists/hands to use the keyboard. The representative also did not agree that the worker would use the keyboard 12 hours a day with his left hand but he would use it for approximately a half day. The worker’s role was not to sit at the keyboard all day. He said in 2001, the worker started to use a normal keyboard (without the plastic covering) which was keyboard driven and then in the late fall they started to use the mouse.

A WCB rehabilitation specialist attended the work site and performed a job analysis in May 2007. In her report of May 7, 2007, she stated the employer provided a newer model of the previously used keyboard. The worker stated the keys were easier to push and it was on an angled stand, where the keyboard he used was flat. The specialist stated the worker was right handed. His symptoms were greater in his left than the right wrist. He reported when using the mylar keyboard he would make notes with his right, and enter more commands with his left. He reported this is the only activity he has completed on a regular basis where there would have been more activity with his non dominant hand.

Worker’s position:

The worker contended in his Appeal of Claims form received June 18, 2007 that his left CTS condition was caused from using the Bailey Computer mylar covered keyboard, that was in service between 1992 and 2001.

Employer’s position:

The employer contended that the worker’s employment was not the cause of his bilateral CTS condition as his use of a keyboard was approximately 2 to 3 hours per shift, the keyboarding he did was not performed in a conventional manner, there was no force involved, and there would be breaks in between use.

Analysis:

As the background notes indicate, this is a case where the worker considers that his bilateral CTS is causally related to the computer work he is required to perform on a daily basis. The panel carefully reviewed the submissions on file from the worker and his employer regarding his job duties along with the worksite and job analysis conducted by the WCB rehabilitation specialist on May 7, 2007.

To accept the worker’s appeal, we must find on a balance of probabilities that he suffered a workplace accident within the meaning of subsections 4(1) and 1(1) of The Workers Compensation Act (the Act). In particular, we must find that his bilateral CTS is causally related to his work duties. Based on the evidence before us, the panel is unable to make that finding.

CTS is defined as the impairment of the motor and/or sensory function of the median nerve as it traverses through the carpel tunnel. It is caused either by internal swelling of the median nerve or by external compression of the median nerve by one of the many surrounding structures of the wrist. CTS has a variety of causes. It can be caused by underlying systemic conditions such as rheumatoid arthritis, osteoarthritis, hypothyroidism, and diabetes. It can also be caused by some types of work activities. Its cause may also be unknown. Occupational factors most commonly accepted to be associated with CTS include a wrist injury, frequent use of vibrating hand tools, or any repetitive forceful motion with the wrist bent, especially when done for prolonged periods without rest. It is generally considered that the greatest frequency of occupationally related CTS is found where job duties involve high force and high repetition. As well, where an individual has bilateral CTS, there is a stronger inference that the cause is systematic in nature rather than occupationally caused. Bilateral CTS can, however, arise from work duties where the CTS occupational risk factors are present for both wrists/hands.

The worker’s job duties required careful examination to determine whether or not they caused his bilateral CTS.

In reviewing the evidence before us, we are unable to find a link between his job duties on the two computers and his CTS. The Mylar keyboard is not used for data entry but instead for commands. This would assume a longer time gap between commands, as compared to continuous key strokes entering data. Both the worker and the employer agree the time he spends on the computer to be around 3 hours of his 8 hour shift. The time spent is not constant although the computer time may be more or less depending on the day. The worker is also responsible for attending meetings, dealing with other employment matters and conducting tours or inspections of the operation.