The employee appeals from the compensation judge’s calculation of the employee’s weekly wage.  The employer and insurer cross-appeal from the compensation judge’s findings that there is a causal connection between the employee’s work duties for the employer and his cervical spine condition and the award of cervical fusion surgery.  We affirm.

Ted N. Flaskamp, the employee, was hired by Northwest Airlines (NWA), the employer, in April 1990 as an aircraft cleaner.  Initially, the employee worked cleaning the interior of airplanes.  In early 1991, the employee moved to a crew that cleaned the exterior of airplanes.  To perform this job, the employee used a stick brush in an overhead position and performed pressurized washing, application of chemical sprays, hand cleaning and vacuuming.  In the winters, the crew deiced the airplanes.  In approximately 1993, the employee worked in the C hanger where he washed and cleaned both the interior and exterior of airplanes that came in for periodic checks.  The employee used a pressure hose to clean the plane and waxed and buffed the exterior of the plane and the engine.  Inside the aircraft, the employee stripped the plane down to a skeleton and cleaned the plane with a power washer or by hand.  In approximately 2002, the employee worked as an aircraft line cleaner/picker where he was responsible for cleaning the inside of airplanes between flights.  The employee cleaned the bathrooms and floors inside the aircraft, picked up trash, and placed pillows and blankets in the overhead bins.  The employee performed this job until he left the employ of NWA on April 20, 2005.

On September 28, 2004, the employee saw Dr. Terry Kopp for a physical examination.  The employee complained of headaches over the past few weeks and tendinitis in his right elbow.  On examination, the doctor noted no tenderness over the employee’s cervical spine.  On March 30, 2005, the employee saw Dr. Steven Johnson at the Quello Clinic complaining of left-sided neck pain, dizziness, and tingling in his fingers over the past six months.  The doctor ordered a cervical MRI scan that showed disc herniations at C3-4, C4-5 and C5-6, with mild cord deformity and central canal stenosis.  On April 4, 2005, the employee saw Dr. Kevin O’Connell complaining of headaches and neck pain with numbness in his hands.  The doctor diagnosed degenerative disc disease and stated there was “nothing specific about his symptoms to point to work-related causation.  I am not convinced that his headaches and hand numbness are attributable to his cervical disc condition.”  (Pet. Ex. A-5.)

Dr. Johnson referred the employee to Dr. Glenn Buttermann, an orthopedic surgeon, who he saw on May 2, 2005.  Dr. Buttermann diagnosed multilevel cervical spinal stenosis from C3 to C6.  A CT myelogram of the cervical spine demonstrated moderately advanced multilevel disc degeneration with disc herniations at C4-5 and C5-6 with spinal stenosis.  On May 16, 2005, Dr. Buttermann recommended epidural steroid injections, but opined surgery was probably inevitable.

On December 27, 2005, Dr. Buttermann performed an anterior cervical discectomy and fusion.  In the hospital discharge summary, Dr. Buttermann stated his post operative diagnosis was spinal stenosis from C3 to C6 with a C5-6 disc herniation.  The doctor stated his work up revealed “congenital stenosis as well as spondylosis, but most significantly a disc herniation at C5-6.”  (Rep. Ex. 3.)

By report dated April 26, 2006, Dr. Johnson stated:

Dr. Terry Hood, a neurosurgeon, reviewed the employee’s medical records at the request of the employer and insurer and his deposition was taken in June 2006.  The doctor diagnosed multilevel degenerative disc disease with multilevel small disc protrusions, and mild to moderate bilateral foraminal stenosis at C3-4.  Dr. Hood stated the activities the employee performed at work did not seem out-of-the ordinary or to the level which would contribute to his degenerative disc disease.  Dr. Hood opined the employee’s work activities with NWA were not a substantial or contributing cause to the employee’s cervical condition.  Dr. Hood stated he would have obtained additional testing, including discography and an EMG, prior to recommending surgery.  The doctor opined more testing was necessary to determine whether the employee needed fusion surgery due to his spinal condition.

The deposition of Dr. Buttermann was obtained in July 2006.  The doctor’s diagnosis was spinal stenosis from C3 to C6 with a disc herniation at C4-5.  The surgery, Dr. Buttermann testified, confirmed his diagnosis plus he found a C5-6 disc herniation with an extruded disc fragment.  Dr. Buttermann was presented with a hypothetical question outlining the employee’s work activities at NWA and opined those activities were a probable cause for the employee’s neck symptoms and the need for surgery.  The doctor stated neither a discogram nor an EMG were necessary prior to surgery.

The employee’s claim for benefits was heard before a compensation judge.  In a findings and order, the compensation judge found the employee sustained a Gillette-type^[1] personal injury on April 2, 2005, causally related to his work with the employer.  The judge further found the employee’s personal injury was a substantial and contributing cause of the need for surgery.  The judge found the employee’s wage during the 26 weeks prior to his personal injury was irregular, and concluded the employee’s weekly wage was $757.97.  The employee appeals the compensation judge’s weekly wage finding and the employer and insurer cross-appeal the compensation judge’s findings on causation.

The employee testified his regular schedule at NWA was an eight-hour shift, five days a week.  He stated that on occasion, if things were slow, NWA gave employees a company convenience day which allowed him to leave early and he was not paid.  During the 26-week period prior to April 2, 2005, the employee testified he did not take any personal days off.  The employee was paid every other week and during two of the thirteen bi-weekly pay periods, the employee was paid overtime.

The compensation judge concluded the employee’s overtime prior to April 2, 2005, was neither regular nor frequent.  The compensation judge apparently also concluded the evidence was insufficient to compute a daily wage under Minn. Stat. § 176.011, subd. 3, or a weekly wage under subd. 18.  Therefore, the compensation judge averaged the employee’s earnings, excluding overtime, over a 26-week period and arrived at a weekly wage of $757.97.^[2]  The employee argues the compensation judge erred in this decision and misapplied the case of Valentine v. Anderson Trucking Serv., 276 N.W.2d 649, 31 W.C.D. 379 (Minn. 1979).  The employee contends he was hired for a 40-hour week at $20.40 an hour and is entitled to a weekly wage of $816.00.

In the Valentine case, the employee testified he was hired to work nine hours a day at $4.05 an hour.  During the 26 weeks preceding the injury, however, wage payments to the employee varied.  Accordingly, the employer argued the employee’s wages were “irregular or difficult to determine” as provided in Minn. Stat. § 176.011, subd. 3, which would then require the use of the 26-week formula.  In rejecting this argument, the Minnesota Supreme Court stated:

Similarly, in Brunkow v. Red Wing Shoe Co., 43 W.C.D. 232 (W.C.C.A. 1990), the employee’s wage rate varied depending on productivity.  The compensation judge calculated an hourly rate and multiplied that rate by 40 hours to determine the employee’s weekly wage.  On appeal, the employer and insurer contended the judge erred in using a 40-hour week because the employee typically worked less than 40 hours a week due to the employer’s liberal policy which allowed employees to take ample time off without pay.  The Workers’ Compensation Court of Appeals noted that the employee seldom worked a full 80 hours in any of the thirteen bi-weekly pay periods prior to the injury because of sick leave or vacation.  The court stated that time off for sick leave, holidays or vacation is not a basis for determining whether the number of days per week that an employee works is irregular or substantially varied from a normal work week requiring a 26-week computation under Minn. Stat. § 176.011, subd. 18.

In this case, the employee worked 46.5 hours in the pay period ending October 9, 2004, 62.5 hours in the week ending November 20, 2004, 69.32 hours in the week ending January 1, 2005, and 76.5 hours during the period ending February 12, 2005.  In each of the other nine bi-weekly payroll periods, the employee worked at least 79 hours.  The employee testified he had a regular schedule of eight hours a day, five days a week.  When asked why his time records reflected less than 40 hour weeks, the employee testified:

In Valentine and Brunkow, time cards demonstrated the varied wage payments were due to legal holidays, vacation days, sick leave and time off for personal reasons.  The evidence in this case lacks that specificity.  The employee did not specifically testify he received vacation pay, holiday pay, or sick leave pay during any of the thirteen bi-weekly payroll periods prior to his injury.  Although the employee explained that he occasionally left early under the company convenience policy, he did not testify that was the reason he worked only 62.5 hours in November 2004 or 69.32 hours in January 2005.  Based upon the evidence at the hearing, the compensation judge could reasonably conclude the employee failed to establish that the Valentine holding was applicable, and, could conclude the employee’s earnings were irregular requiring the use of an averaging formula to determine the weekly wage.  Accordingly, the decision of the compensation judge is affirmed.

The cross-appellants contend the compensation judge’s finding of a causal relationship between the employee’s work activities and his neck condition lacks substantial evidentiary support.  They assert the employee’s first complaint of neck pain did not occur until April 2005.  The fact that the employee had no problems while performing his work duties prior to then is not, the employer and insurer contend, consistent with a Gillette-type personal injury.  Rather, they argue the employee’s problems are more consistent with age-related degeneration.  The employer and insurer also point out that Dr. Buttermann’s December 2005 discharge note states the employee had congenital stenosis.  This opinion, the employer and insurer assert, is consistent with that of Dr. O’Connell and Dr. Hood that the condition is not work related.  Accordingly, the cross-appellants argue there is no substantial evidence supporting the compensation judge’s decision.  We are not persuaded.

We acknowledge there are no medical records evidencing the employee sought medical care for neck symptoms, specifically, prior to March 24, 2005.  That fact alone does not, however, require reversal of the compensation judge’s decision.  While evidence of specific work activities causing specific symptoms may be helpful as a practical matter, ultimately, the question of whether the employee sustained a Gillette injury depends primarily on medical opinion.  Steffen v. Target Stores, 517 N.W.2d 579, 50 W.C.D. 464 (Minn. 1994).

Dr. Johnson and Dr. Buttermann opined the employee’s work activities were a substantial contributing cause of the employee’s neck condition and his need for surgery.  Dr. Buttermann explained, in detail, how flexion and extension of the employee’s neck during his work activities would cause his underlying condition and his symptoms.  The opinions of Dr. Johnson and Dr. Buttermann are adequately founded.  We do not find the testimony and opinions of Dr. Buttermann inconsistent as asserted by the employer and insurer.  Although the doctor stated the employee’s stenosis may have been congenital, he unequivocally opined the employee’s work activities substantially aggravated his underlying condition.  While there is medical testimony to the contrary, it is the compensation judge’s responsibility, as the trier of fact, to resolve conflicts in expert testimony.  See Nord v. City of Cook, 360 N.W.2d 337, 37 W.C.D. 364 (Minn. 1985).  Because substantial evidence supports the compensation judge’s causation decision, that decision must be affirmed.  Hengemuhle v. Long Prairie Jaycees, 358 N.W.2d 54, 59, 37 W.C.D. 235, 239 (Minn. 1984).