The Appeal CommissionThe Workers Compensation Act of Manitoba

Background

As stated in the preamble, the worker lost flexion in her right index finger after her right lateral elbow release on January 10, 2005. Since that time, there have been several investigations, examinations and opinions as to whether the surgery caused the right finger condition.

In February 2005, a WCB medical advisor reviewed the file. He did not think that the worker’s right finger condition was caused by surgery, though no rationale was provided for this opinion.

The worker’s family physician and physiotherapist thought that the worker’s right finger condition was consistent with tendon damage and that this damage was likely caused by the surgery.

The worker was then examined by a second WCB medical advisor on April 28, 2005. It was this WCB medical advisor’s opinion that the worker’s right finger condition could have been caused by one of two things: nerve damage or tendon damage. She thought that the worker’s symptoms were more consistent with an anterior interosseous nerve palsy that might have been brought on by ischemia due to the inflation of the tourniquet used during the surgery. She was not sure however, and commented that the operation did not appear prolonged from the operative report, and it was difficult to explain how only that particular nerve branch was affected. She nonetheless noted the temporal relationship between the worker’s symptoms and the surgery. Given the complexity of this issue, she recommended that a neurologist be consulted.

The neurologist was equally perplexed by the worker’s condition. He agreed that it was consistent with either an anterior interosseous nerve syndrome or a tendon injury, though subsequent testing appeared to rule out an anterior interosseous nerve syndrome.

In the meanwhile, the worker returned to the orthopaedic surgeon who performed the surgery for reassessment. He stated that he was puzzled about the worker’s symptoms. Though he thought that the right finger condition was likely a tendon problem, he did not see how that tendon could have been affected by surgery given that the surgical incision was at least 15 cm away from the tendon.

The worker was then referred to a plastic surgeon in July 2005 who sent her to another plastic surgeon for a second opinion. This second plastic surgeon was also confused about the cause of the worker’s symptoms. He questioned a reverse triggering of the index finger caused by the flexor tendon and recommended exploratory surgery to determine the exact cause of the condition.

The worker was then examined by a WCB sports medicine advisor on December 28, 2005. He also concurred that the worker’s condition was caused by either nerve or tendon damage. While he thought it biologically plausible that the tourniquet used during surgery could have caused some ischemia and possible resultant neural inflammation to the proximal nerves, he thought it more likely that the worker’s condition was caused by tendon pathology or tear. He thought however that any tendon pathology was a local phenomenon and not as a result of surgery.

Exploratory surgery performed on February 3, 2006 cleared up the cause of the worker’s symptoms. The February 3, 2006 operative report by the plastic surgeon indicates that the tendons in the worker’s right finger were clear and glided well. Further, there was no obvious obstruction along the right index finger including the A1 pulley. Conversely, the plastic surgeon found a leash of blood vessels running across the median nerve higher up on the forearm. The blood vessels were cut and tied and the anterior interosseous nerve was freed. The surgery was a success. The worker regained flexion of the right index finger and returned to work.

Despite this discovery, the second WCB medical advisor was not convinced that the worker’s right finger condition was related to the surgery. Her reason for this was the lack of a definite diagnosis or pathology and in particular, the fact that the anterior interosseous nerve had not actually been damaged.

The treating plastic surgeon has not provided much comment on whether he thought the surgery caused the worker’s right finger condition. A May 8, 2006 report states that he was not able to say if there was any relationship between her condition and the January 10, 2005 surgery. When further questioned by the worker’s union representative in September 2006, he clarified:

“As mentioned in my operative report, the anterior interosseous nerve was crossed by blood vessels that may have been causing pressure on the nerve. This seems to be a temporary impairment of the nerve. Your letter indicates something about nerve root damage but this is not possible at this level. Also, you mention partial or incomplete nerve palsy and I think this is what she had on the anterior interosseous nerve. This would explain why it affected only one finger. The role of the tourniquet on her arm is not very certain but it may have caused the problem to show up as this would have brought on a second injury to the nerve in addition to the blood vessels crossing the anterior interosseous nerve. This is only a possibility as far as I can see.

I do not have any other explanations as to the reason why the anterior interosseous nerve was not functioning. At this point, I cannot really say what is the cause of her problem with the anterior interosseous except for releasing the blood vessels seemed to have caused recovery…”

The family physician thought that the only explanation for the onset of the worker’s right finger condition was the January 10, 2005 surgery. In a May 16, 2006 report he stated:

“Specific to the function of the right hand, as stated in the above dictation, there were no problems with the index finger prior to the surgery. Subsequent to the surgery, there was definite loss of function. This has improved as a result of an exploratory surgery and removing some entrapment. There was no evidence of entrapment problem prior to the surgery. It is felt therefore that the entrapment of the radial nerve may have been present prior to the surgery without being symptomatic, but following surgery as a result of the procedure, either by positioning or swelling post-operatively in the elbow area, there was expression of this impingement syndrome causing a dysfunction in the hand. This has been improved now by the surgical procedure. It is recommended that therefore [the worker] is now able to return to her previous work environment with the restrictions that have been in place prior to the elbow surgery.”

Analysis

As stated above, the issue before the panel is whether the worker’s right finger condition and the time loss related to this condition should be accepted as a consequence of the January 10, 2005 surgery. Essentially, this issue means that the panel must find on a balance of probabilities that the worker’s right finger condition is causally related to the January 10, 2005 surgery. We are able to make that finding.

As stated, the legal standard of proof before this tribunal is balance of probabilities. Though this standard can and has been expressed in many ways, it is generally described as ‘more likely than not’. In other words, and in this particular case, we must find it more likely than not that the surgery caused the worker’s right finger condition. To be clear, it is not necessary for there to be a ‘clear diagnosis’ or medical certainty. It is sufficient that the worker suffer an injury that more likely than not is a consequence of an accepted surgery.