The employer, Gridor Construction, Inc., and its insurer, Westfield Insurance Company, appeal from the compensation judge’s determination that the employee sustained a Gillette^[1] injury to his low back as the result of his employment with Gridor. We affirm.

Michael S. Dillon, the employee, worked as a union carpenter for many years and began working for Pennco in the late 1980s. On January 15, 2002, he was carrying some wooden support beams when he stepped into an unexpected dip in the ground. The employee stated that he felt his lower back snap and he indicated the belt area as being where he noted the snap.

The employee’s initial treatment was at Health Enhancement, a chiropractic clinic in Bird Island, Minnesota, on January 24, 2002. He received 17 adjustments to his lumbar spine after that date, with the last treatment on March 27, 2002. The employee testified he had to leave the job site early to get to his chiropractic appointments but that otherwise he missed no time from work. Pennco and its insurer, St. Paul Travelers, admitted primary liability for the January 15, 2002, injury.

The employee saw his family doctor, Dr. Paul Thompson, at Prairie Family Practice, for back complaints on March 29, 2002. The history taken by Dr. Thompson was of the employee injuring his low back at work in January but that the back pain was now in the mid to upper back on the left side. Dr. Thompson recommended the use of Aleve for two weeks then suggested the employee stretch and limber up his muscles when he got up in the morning or after his commute. No work restrictions were provided. In his testimony at the hearing, the employee recalled his appointment with Dr. Thompson but did not recall having mid or upper back pain. It was his testimony that his pain was always at the belt level.

The employee was laid off from Pennco at the end of 2002. After that, he worked as a carpenter for a number of other employers. The employee stated that his back was never the same after his 2002 injury, but that he did not treat for his back, at least in part because “for me to come back and ask for time off was just something you don’t do. You just don’t create waves at work, you just work.” Nevertheless, the employee stated that heavy work would increase his low back pain.

On September 13, 2005, the employee returned to Prairie Family Practice and saw Dr. Paul Buhr. His history was

The employee started working at Gridor on September 26, 2005.^[2] The employee testified that he worked on a waste water treatment plant being built in Otsego. His job was to build and handle forms used for concrete work in footings and walls. The employee described his initial work as being “pan work.” By this, he meant using what he referred to as Simon pans as forms in concrete work. The Simon pans were generally eight feet by two feet and would have to be carried and put in place by hand. The pans weighed 80 pounds, and the employee testified he did this work fairly constantly during the first few weeks that he worked at Gridor. The employee recalled one particular instance when he was picking up a pan and he felt a “tweak” in his back. He told his foreman, Steve, on at least three occasions that his back was bothering him. Sometime after his comments to Steve, the employee was transferred from pan work to lighter work where he did not have to lift more than 20 pounds. The employee was never told why this transfer was done.

The employee was laid off from Gridor on November 20, 2005. The employee was given no reason for his lay off at the time. At the hearing, the owner of the company said that the employee was laid off for lack of work but the employee disputed that rationale, stating that people were still being added to the crew at the job site when he was let go. The employee testified his back condition worsened during his employment with Gridor. Before he began working there, his pain was generally at a level of four on a 10-point scale and when he left it was at an eight.

The employee first saw Dr. Heeter for his low back pain on October 11, 2005. He gave a history to Dr. Heeter that his back pain began about four years before when he stepped into a hole while carrying a beam. Dr. Heeter recommended an epidural steroid injection, blood tests to rule out rheumatoid arthritis, and the use of Clinoril. The employee reported about 80% improvement in his back pain after the steroid injection. Dr. Heeter released the employee to work without restrictions and continued the employee without restrictions when he saw him again on January 3, 2006.

The employee was laid off and received unemployment benefits until March 2006, when he went to work for Madsen-Johnson in his usual position as a carpenter. He worked there until August 2006, when he went to work for Knutson Corporation. He worked for Knutson as a carpenter through December 2006.

The employee filed a claim petition in February 2006, alleging he sustained a Gillette injury to his low back from his employment at Gridor on November 20, 2005.

The employee was evaluated by Dr. Mark Friedland on May 16, 2006, on behalf of Gridor. At the time of the evaluation, the employee was working for Madsen-Johnson. Dr. Friedland diagnosed the employee as having “L4-5 and L5-S1 degenerative disc disease and facet arthrosis with minimal grade 1 degenerative L4 and L5 spondylolisthesis.” It was his opinion that the employee did not have a Gillette injury at Gridor and that the January 2002 injury at Pennco was a substantial contributing factor in the employee’s ongoing low back condition. Dr. Friedland also concluded that the employee needed no work restrictions for his low back and no ongoing medical care.

The employee was also evaluated by Dr. Mark Gregerson for Pennco on October 11, 2006. Based essentially on the same information that had been provided to Dr. Friedland, Dr. Gregerson concluded that the employee had sustained a Gillette injury at Gridor which culminated on or about November 20, 2005. Dr. Gregerson further stated that the employee had no restrictions and needed no further medical treatment.

The employee testified that he had a hard time working eight hours a day when he was working at Knutson. He said that his back really hurt but that he kept working because he was making more money than he ever had before. He saw Dr. Heeter again on January 2, 2007, and expressed his concern about his ability to continue working as a carpenter. Dr. Heeter placed him on Indocin but did not impose any work restrictions. When he returned on February 27, the employee told Dr. Heeter that, “his pain is the same today if not worse as compared to his initial visit in 2005.” Dr. Heeter referred the employee to the Institute for Low Back and Neck Care and placed work restrictions on the employee of no lifting over 20 pounds.

The employee was seen by Dr. Richard Salib on March 15, 2007, and a recommendation was made for a medial branch block at L4-5. That procedure was done on April 9, but the employee reported no relief from his pain. On May 3, 2007, Dr. Salib recommended anterior fusion at L4-5 and L5-S1. As of the date of hearing, the employee had not had surgery because of the dispute over which insurer was liable for medical expenses.

Dr. Salib issued a report of August 7, 2007, in which he addressed the question of causation. He agreed with Dr. Gregerson that the employee’s low back condition was due both to the 2002 work injury and to a Gillette at Gridor. He apportioned 50% liability to each injury, placed work restrictions on the employee of sedentary activity only on a part-time basis. He also indicated the employee had 10% permanent partial disability but had not reached maximum medical improvement.

Dr. Heeter provided his opinion on the medical issues in this case in a report dated October 10, 2007. He indicated that in preparing his report, he had reviewed his records from treating the employee and had reviewed outside records, including the IME opinions of Dr. Gregerson and Dr. Friedland. Dr. Heeter’s final diagnosis was “L5-S1 disc degeneration with ring osteophytes and recess stenosis with annular ligament tearing.” The employee’s diagnosis also included degenerative disc disease at L4-5 with anterolisthesis and facet arthritis.

It was Dr. Heeter’s opinion that the January 2, 2002, injury was a substantial contributing factor in the employee’s low back condition. He also concluded the employee had sustained a Gillette injury to the low back at Gridor from his work there between September 26, 2005 to November 20, 2005. He apportioned liability 75% to Pennco and 25% to Gridor. Dr. Heeter indicated the employee was restricted to lifting and carrying no more than 20 pounds, and that the employee should avoid forward bending and twisting. The employee was also given a rating of 10% permanent partial disability under Minn. R. 5223.0390, subp. 3.C.(2).

Dr. Friedland testified by deposition on October 24, 2007. In large part, his opinion was substantially unchanged from that set forth in his 2006 report. He stated his conclusion, based on his review of additional records, that the employee did not sustain a Gillette injury at Gridor and that the employee’s ongoing symptoms were the result of his 2002 work injury.

This matter was heard by Compensation Judge Harold Schultz, II on November 8, 2007. In his findings and order issued January 22, 2008, the compensation judge determined that the January 2002, work injury was a permanent injury and that the employee had also sustained a Gillette injury at Gridor as of November 20, 2005. The compensation judge awarded wage loss benefits and medical expenses to the employee and apportioned liability 75% to Pennco and 25% to Gridor. In his memorandum, the compensation judge found the employee had provided credible testimony and he specifically adopted the opinion of Dr. Heeter. Gridor appeals.

Gridor appeals the compensation judge’s determination that the employee sustained a Gillette injury at Gridor as of November 20, 2005. Gridor contends that there is insufficient evidence to establish causation and that there is no ascertainable event for such an injury.

We find substantial evidence in the record to support the compensation judge’s finding that the employee sustained a Gillette injury at Gridor.

The compensation judge relied on Dr. Heeter’s opinion in making his determination. The question of whether a Gillette injury has been established is in substantial part one of medical evidence. Steffen v. Target Stores, 517 N.W.2d 579, 50 W.C.D. 464 (Minn. 1994). We have previously held that a well-founded medical opinion can serve as the basis for a compensation judge’s finding of a Gillette injury. Stevens v. AAA Cooper Transp., 65 W.C.D. 431 (W.C.C.A. 2005); Walsh v. Dassel Lakeside Cmty. Home, No. WC04-335 (W.C.C.A. June 21, 2005). Gridor argues however that Dr. Heeter’s opinion lacked foundation and could not be the basis for the compensation judge’s decision. We disagree.

Gridor’s initial argument on foundation is that Dr. Heeter was not aware of the employee’s employment after Gridor. The argument is based on a single sentence from a letter the employee’s attorney sent to Dr. Heeter in which the attorney stated, “we originally filed a claim petition naming an 11/20/05 repetitive Gillette-type injury against the employee’s last employer, Gridor.” Gridor’s conclusion is that Dr. Heeter relied on this statement and was not aware that the employee had any employment after Gridor.

We do not believe the inference Gridor wishes us to draw follows from the evidence. First, the letter says only that when the claim petition was filed in February 2006, Gridor was the last employer. The statement in the letter is correct and the letter does not suggest that the employee never worked again. More importantly, Dr. Heeter’s report states that he reviewed Dr. Friedland’s IME report from May 2006, a report that discussed the employee’s work history after Gridor. There is no basis for concluding that Dr. Heeter found a Gillette injury at Gridor only because he thought Gridor was the last employer.

Gridor also argues that Dr. Heeter was not aware of the employee’s work duties at Gridor. In his January 2, 2007, office chart, Dr. Heeter noted that the employee discussed with him his employability as a carpenter. Further, Dr. Friedland’s reports detailed the duties of the employee at Gridor. Dr. Friedland’s report also referred to the employee’s statement, later affirmed by the employee in his testimony at the hearing, that his back discomfort increased during his employment at Gridor. We believe this evidence provided sufficient information for Dr. Heeter to identify the employee’s work activities and established foundation for Dr. Heeter’s opinion.

Gridor also argues that the employee never told any of his treating doctors that he had sustained a Gillette injury at Gridor. There is no requirement that establishing a Gillette injury is dependent on an employee being able to make a medical diagnosis. The employee’s testimony was consistent with the information provided to Dr. Heeter and Dr. Friedland. As we noted previously, Dr. Heeter’s opinion is well founded and serves as a basis for the compensation judge’s determination on this issue.

Gridor argues in its brief that Dr. Friedland had the best foundation for a medical opinion and that his opinion should have been adopted by the compensation judge. But Dr. Heeter, having reviewed Dr. Friedland’s report, had the same foundation as Dr. Friedland and, in addition, had the benefit of treating the employee. This matter is one in which the compensation judge chose between competing medical opinions. Nord v. City of Cook, 360 N.W.2d 337, 37 W.C.D. 364 (Minn. 1985); Priglmeier v. Stellar Concrete, 65 W.C.D. 384 (W.C.C.A. 2005). As we have said in other cases as well, this court will generally affirm a compensation judge’s decision which is based on a choice between competing medical opinions. Johnson v. Sico, Inc., No. WC05-226 (W.C.C.A. Jan. 20, 2006); King v. Woodsmen Midwest, Inc., 65 W.C.D. 175 (W.C.C.A. 2004). We do so here.

Gridor argues that it was error for the compensation judge to find a Gillette injury at Gridor because the employee was not disabled during his employment there. He was not taken off work because of his work injury and he was laid off from his employment for economic reasons. Gridor contends that, as a result, there was no ascertainable event to establish a Gillette injury. We are not convinced.

A Gillette injury is generally found to have occurred where cumulative subclinical trauma results in disability. Disability in the sense of inability to work is not an absolute requirement for a Gillette injury, however. The Minnesota Supreme Court has held that there may be more than one type of ascertainable event which is evidence of a compensable injury. Schnurrer v. Hoerner-Waldorf, 345 N.W.2d 230, 360 W.C.D. 504 (Minn. 1984). The court specifically found in that case that when the foreman removed the employee from his regular job because of his physical condition, an ascertainable event occurred.

In the present case, the employee testified that after handling Simon pans for some weeks and after his back pain was worse, he had told his foreman of his back pain and was placed in a lighter job shortly thereafter. It is true, as Gridor points out, that this reassignment was not made at the direction of a medical doctor, but we find nothing in the case law which requires a medical imprimatur before an ascertainable event can be found to exist.

Further, this court has previously held that the date when the employee was laid off for economic reasons was an ascertainable event for a Gillette injury when the employee did not seek medical attention until after his employment had ended. Yates v. Muller Logging, Inc., No. WC06-210 (W.C.C.A. Jan. 3, 2007). Finally, while Gridor argues that the employee was laid off for economic reasons, the compensation judge did not make that finding. The compensation judge found only that the employee was “let go.”

We find substantial evidence to support the compensation judge’s determination that November 20, 2005, was an appropriate date for the employee’s Gillette injury.

Gridor questions the award of medical and wage loss benefits to the employee after June 1, 2007. Gridor’s claims that even if there was a Gillette injury at Gridor, it was a temporary injury which had resolved before that date. The compensation judge, however, adopted the opinion of Dr. Heeter who concluded the employee’s ongoing condition was the combined result of the 2002 and 2005 work injuries. Gridor also challenges the award of wage loss benefits because of the lack of job search by the employee. Dr. Salib’s records, however, serve as support for the determination that the employee was not able to be employed until after surgery.

The decision of the compensation judge is affirmed.