The employee appeals from the discontinuance of benefits based on the finding that his work injuries are not a substantial contributing cause of his current disability.  We affirm.

The employee, Stanley Cox, started working for the employer, the Minneapolis Public Schools, as a bus driver in 1995.  A civil service medical examination was performed on April 6, 1995, which revealed the employee to be in generally good health with good back flexion and good abdominal muscle strength.  Back extension, back strength, and hamstring flexibility were rated only as “marginal.”  The employee was noted to be 5'7" in height and his weight was given as 344 pounds.  The employee’s job typically involved up to 50 hours per week driving school bus routes during the school year, with a somewhat reduced schedule of work during summer school periods.

On February 11, 1998, the employee sustained an admitted injury to his low and mid back and neck when a school bus he was driving was rear-ended by an automobile.  He was seen at the Abbott Northwestern Hospital emergency room that same day with lower back pain, left neck pain and shoulder pain.  The diagnosis was low back strain and cervical strain^[1].  The employee was given a prescription for Flexeril and Tylenol and placed on work restrictions for light duty work with no bus driving for the next two days.

On the following day, February 12, 1998, the employee was evaluated by Dr. Jeffrey Larson, M.D., at the Allina Occupational Health Services.  His low back function was not tested due to stiffness and pain.  There were no radicular symptoms and his lower extremities had normal strength, reflexes and sensation.  Straight leg raising was questionably positive at 15 degrees with some hip pain.  Dr. Larson diagnosed a lumbosacral strain with spasm.  The employee was continued on restrictions from driving.

The employee returned to Allina Occupational Health Services on February 15, 1998, where he was seen by Dr. Norman Westhoff, M.D.  He continued to have pain in the lower back without radiation to the legs and no motor, sensory or reflex deficits.  He was not seen to be in acute distress and was able to stand and walk comfortably.  No spasm was noted.  Lumbar flexion was limited to about 30 degrees, and extension to about 5 degrees.  The employee was advised to avoid driving at work and to limit lifting to 10 pounds and limit bending and twisting.  He was referred for two weeks of physical therapy, three times per week.

On February 16, 1998, the employee sought chiropractic treatment from Dr. James P. Seim, D.C., at the Snelling Chiropractic Clinic.  Dr. Seim noted some spasm in the employee’s lumbar spine bilaterally, right greater than left, most notably at L4-5.  The employee thereafter began regular chiropractic treatment with Dr. Seim.

X-rays of the employee’s lumbar spine were done on February 18, 1998.  They showed normal alignment of the discs, with slight disc space narrowing at the L3-4 level.  There was also evidence of degenerative disc disease and secondary osteoarthritis affecting the L3-4 level, but no evidence of recent bone or joint injury.

On March 5, 1998, the employee was seen by Dr. Mary Jane Chiasson, D.O., at the Noran Neurological Clinic for a second opinion at the request of Dr. Seim.  The employee was noted to weigh about 320 pounds on that date.  He reported some increased pain in his left buttocks when the leg was straightened, but no radiation of pain down the leg.  Dr. Chiasson noted shortening of the left psoas muscles, which she thought might be secondary to the employee’s motor vehicle accident.  She recommended a progressive exercise program to lengthen the psoas muscles and improve flexibility at the pelvis.

The employee returned to Dr. Westhoff at Allina on March 16, 1998.  He reported that he was now treating with a chiropractor.  He was still having back pain and had continued to remain off work, but thought he could resume work if he could get an “air ride” seat in his school bus.  Dr. Westhoff noted that his examination showed the employee to be quite deconditioned and obese, with a limited range of motion in the spine.  The employee stated that his personal physician had told him he had a degenerative disc problem, and Dr. Westhoff noted that this would be consistent with his history and examination.  He diagnosed a low back syndrome, placed the employee on unrestricted work status, and did not schedule further follow up.

On March 25, 1998, the employee returned to Dr. Westhoff because he wanted restrictions due to continued low back pain.  He told the doctor that his chiropractor had placed him on significant restrictions for bending, lifting, sitting, stooping, and wanted to know if Dr. Westhoff agreed with this.  Dr. Westhoff wrote that, in his opinion, the employee needed no restrictions.  The employee continued chiropractic treatment with Dr. Seim through May 1, 1998.

On July 28, 1998, the employee returned to Dr. Chiasson at the Noran Clinic complaining of low back pain on awakening.  Dr. Chiasson noted that the employee continued to show a forward flexed posture.  She diagnosed a lumbar sprain/strain with bilateral psoas shortening, and recommended that the employee resume treatment with Dr. Seim and participate in pool therapy and an exercise program.

On September 28, 1998, the employee returned to Dr. Seim for evaluation, and on October 5, 1998, Dr. Seim wrote a narrative report discussing the employee’s condition and treatment.  Dr. Seim stated there was radiographic evidence of pre-existing degenerative changes in the lumbar spine, but concluded these had not been sufficient to precipitate a symptomatic condition.  He diagnosed the employee as suffering from the residual effects of a chronic traumatic lumbosacral spinal strain/sprain in the form of a regional myofascial pain syndrome, complicated by degenerative disc disease at L3-4.  He opined that the employee had permanent residual impairment and that his condition would progressively worsen with time.  Dr. Seim recommended permanent restrictions against bending from the waist, repetitive turning or twisting, or lifting more than 55 pounds.  For bus driving, Dr. Seim recommended that the employee have an air ride seat and an air-powered door.  On May 21, 1999, Dr. Seim rated the employee with a permanent partial disability of 7 percent of the lumbar spine, with maximum medical improvement having been reached by March 3, 1999.^[2]

The employee was evaluated by Dr. Mark Thomas, M.D., an orthopedic surgeon, on behalf of the self-insured employer, on September 16, 1999.   The employee was then no longer treating for his injury but reported symptoms of throbbing pain in his low back. Dr. Thomas noted that the employee was grossly obese, but seated himself comfortably, had normal balance, and walked on his heels and toes without difficulty.  Lumbar motion was mildly restricted, with flexion at 60 degrees and extension at 20 degrees.  There was normal muscle tone and motor strength and the neurological examination was entirely normal.  Straight leg raising was negative.  Dr. Thomas opined that, considering the difference in size and mass of the vehicles in the accident, little force would have been transmitted to the employee.  He concluded that the work injury had caused only a low back strain which had since resolved without permanent partial disability or any need for restrictions.  He diagnosed the employee with chronic backache and underlying degenerative disc disease which, in his opinion, related entirely to his obesity and deconditioning.  He noted that the employee had been working in his normal capacity since March 1998 and concluded that MMI was reached on or about March 16, 1998.  He saw no indication for further treatment, though he thought the employee could benefit from a self-directed program of walking and exercise and should pursue weight loss.

In February 2000, the employee and the self-insured employer entered into a stipulation for settlement of the employee’s disputed claim for permanent partial disability, the employer having already paid medical expenses and temporary total disability compensation from the date of injury through March 16, 1998, when the employee had returned to work.  The stipulation closed out all claims for permanent partial disability to 17 percent of the whole body, of which seven percent represented the employee’s alleged low back permanency and 10 percent permanency from his cervical condition.  An Award on Stipulation was served and filed on February 15, 2000.

The employee thereafter continued working at his regular job for the employer, without further medical or chiropractic treatment, until December 5, 2001, when the employee slipped and fell on the steps of his school bus.  He returned to Dr. Seim and resumed chiropractic treatment that same day.  Dr. Seim took the employee off work and referred the employee to his primary care physician for x-rays.

On December 11, 2001, the employee saw Dr. Amir Bhalwany, MD at his primary care clinic, the Aspen Medical Group.  Lumbar spine x-rays were performed which showed five lumbar vertebrae in adequate alignment and no evidence for acute compression fractures.  There was degenerative disc disease at L3-4 with narrowing of that disc as well as spurring.

On January 30, 2002, the employee was seen again at the Aspen Group by Dr. Bhalwany for low back pain.  His pain had been improving, but had now worsened again.  Dr. Bhalwany told the employee his symptoms sounded like muscle strain.  He advised the use of Percocet and rest.  Dr. Bhalwany also recommended an MRI to rule out any nerve root impingement.

Because of the employee’s size and weight, stated to be 360 pounds, an MRI could not be performed.  Instead, he underwent a CT scan of the lumbar spine on February 4, 2002.  The CT showed no nerve root compromise or stenosis.  There was anterior end plate spurring and early degenerative disc change at L3-4.

The employee treated with his chiropractor through February 26, 2002.  On February 27, he was seen at the Aspen Clinic by Dr. Daniel Rischall, M.D.  The employee reported that his back pain had improved although he still had some discomfort.  Dr. Rischall recommended that the employee return to work part time, and then proceed to full time if that went well.

The employee then went to the Noran Clinic on March 5, 2002, to see Dr. Chiasson.  He had not been there since July 1998.  He reported that he had recovered fairly well from his 1998 work injury but had low back pain, pain in the buttocks, and pain down both legs after slipping on the steps of his bus in December 2001.  Dr. Chiasson diagnosed a low back injury with a persisting lumbosacral sprain/strain.  She thought it likely that he would get back to full work quickly, but recommended that his hours be increased slowly to allow him to adjust.

The employee returned to Dr. Chiasson on March 14.  She noted his condition was unchanged.  The employee reported that he had been tolerating his work activities poorly, so she reduced his work hours.  She noted that the employee had a chronic problem with short psoas muscles bilaterally, and that he had poor pelvic control, was obese, and had limited lumbo-pelvic flexion.  She recommended eight to twelve sessions of physical therapy and pool therapy.

On April 25, 2002, the employee was evaluated by Dr. David W. Boxall, M.D., on behalf of the self-insured employer.  The employee weighed 385 pounds.  He showed touch-me-not tenderness in the low back and complained of tenderness in the left flank, but without any associated spasm or guarding.  His neurological examination was essentially normal.  Dr. Boxall found no evidence of an ongoing injury from the December 5, 2001, incident, and opined that maximum medical improvement had been reached as of February 25, 2002, with no permanent partial disability.  He had no suggestions for further treatment and did not think the employee needed any work restrictions.

The employee was seen by Dr. David Berman, M.D., at the Aspen Clinic on January 31, 2003.  The employee was back to work.  He had no pain radiating into his legs.  Straight leg raising was negative.  There was some mild tenderness over the lower spine.  Dr. Berman noted that x-rays had shown degenerative disk disease at L3 with spurring of the lower thoracic and lumbar spine.  The employee admitted that he had experienced back pain for most of his life.  Dr. Berman diagnosed degenerative osteoarthritis of the lumbar spine with chronic low back pain.  The employee’s weight was 389 pounds.  Dr. Berman concluded that the employee’s main problem was his morbid obesity.  He suggested that the employee consider gastric bypass surgery.

The employee returned to Dr. Berman on July 19, 2004, seeking a refill of his Percocet.  He reported that he was getting along reasonably well.  Dr. Berman noted that the employee weighed about 400 pounds and again recommended consideration of a gastric bypass.

On September 20, 2004, the employee returned to the Aspen Clinic with back discomfort which had worsened over the last 10 days or so.  He reported sharp discomfort radiating to his legs.  He was referred for physical therapy.  On October 13, 2004, the employee returned to the Aspen Clinic with ongoing back pain.  He was working 48 hours per week driving a school bus.  Straight leg raising was now positive into the left leg.  Physical therapy was continued.

On October 27, 2004, the employee returned to Dr. John Raines at the Aspen Clinic reporting that his pain had gotten worse and that he had been unable to work for the last few days.  He had only gone to physical therapy once, and had decided not to return until after he consulted with Dr. Chiasson in November.  Dr. Raines stated he was frustrated that the employee had deferred physical therapy for six weeks, and did not know how best to proceed.  He decided to simply continue the employee off work until he was seen by Dr. Chiasson.

Dr. Chiasson saw the employee on November 4, 2004.  She noted that he had last been seen in 2002, when he had been doing well.  The employee reported that he recently developed pain which would not go away with exercise and had been taken off work.  Dr. Chiasson recommended an MRI scan due to concern over a possible lumbar radiculopathy.  The MRI, performed on November 9, 2004, showed a small midline disc herniation at L5-S1 without significant encroachment on the central canal.  There was minimal bulging and osteophyte formation at L4-5, L3-4, and L1-2, without significant central or lateral canal stenosis, and without nerve root or ganglionic impingement.  Dr. Chiasson noted on that date that she thought that the employee’s current low back pain was a combination of the effects of his previous injury and of a seated work position.

On November 15, 2004, the employee returned to Dr. Berman at the Aspen Clinic. Dr. Berman diagnosed chronic low back pain with mild lumbar disc disease.  He noted that the employee weighed more than 350 pounds, and referred him to a dietician.  He thought the employee would require a gastric bypass.

The employee was seen for an initial physical therapy evaluation at Therapy Partners on November 22, 2004.  He gave a history of noting the onset of pain on October 4, 2004, while sitting at home on a work break during a split shift.  He was at first unable to get out of his chair, but finally did manage to get up and to finish his work day.  Since then, he had experienced increasing pain with some missed work days.  Since October 25, he had been off work completely.  Short term treatment goals were established as increasing lower extremity strength and range of trunk motion, to return to work at least half time, and to develop a home exercise program.  Long term goals were a full time return to work, resumption of independence with home exercise, and weight loss.

On December 14, 2004, a registered nurse at the Noran Clinic noted that neither the patient nor his therapist thought there had been any progress.  The employee had not found any treatment helpful to reduce pain except medication.  Physical therapy was placed on hold, Celebrex was prescribed, and pool therapy was recommended.  An epidural injection was recommended at L5-S1 to reduce inflammation.  The employee was continued off work.

On January 1, 2005, the employee returned to Dr. Chiasson, who noted that treatment to date had not controlled the employee’s low back pain.  No steroid injection had been done because the employee was allergic to steroids.  Pool therapy did give the employee pain relief, but only while he was in the pool and the weight was taken off his back.  Based on this, Dr. Chiasson opined that the employee needed significant weight loss assistance. She recommended a consultation for possible bariatric surgery, with the goal being to reduce the compressive forces on the employee’s lumbar spine and thus reduce pain.  She further noted that, with the employee’s weight, he would be a poor candidate for lumbar spine surgery.  She ordered that the employee remain off work.

The employee was seen for a nutritional consultation at the Aspen Clinic on April 20, 2005.  It was impossible to weigh him on the scale, but the dietician estimated his weight at about 380 pounds.  She recommended a diet with reduced caloric intake.

On April 21, 2005, the employee was seen by Dr. Mark Thomas, M.D., for an evaluation on behalf of the self-insured employer.  He told Dr. Thomas that he had sustained injury to his back in October 2004 while driving the school bus, when he noticed pain from the seat moving up and down, and developed such excruciating pain that he could not get out of the bus at the end of the day.  He stated that Dr. Chiasson had recommended lumbar fusion but that he had to get some weight off first.  His current treatment was pool therapy and it did not provide any improvement.  Pain was localized in the lower lumbar region.  The employee rated his pain at 10+ on a scale of 10.  On examination, Dr. Thomas noted limited motion in the employee’s low back.  There was numbness in the left posterior thigh, but no radicular pain in the lower extremities.  The employee’s lower extremities were neurologically intact and straight leg raising was negative.  Dr. Thomas diagnosed chronic backache.  He opined that the employee’s low back condition was the result of his morbid obesity, and not of work activities.  He recommended that the employee follow a regular exercise program.  He agreed that the employee could not perform his school bus driver job, due to his severe subjective pain and use of strong narcotics on a frequent daily basis.  He considered the employee’s work abilities less than sedentary, but attributed his work restrictions solely to his morbid obesity.  Dr. Thomas agreed with the recommendation for a gastric bypass.

On April 26, 2005, the employer filed a notice of intent to discontinue temporary total disability compensation based on Dr. Thomas’ opinion that the employee’s low back condition was not due to a work injury, but only to the employee’s obesity.

The employee was seen by Dr. Chiasson on May 5, 2005.  She continued the employee off work, continued pool therapy, and again recommended a gastric bypass, noting that his weight was making it difficult for him to recover from his injury.  She concluded that he would be unable to return to bus driving in the future regardless of the outcome of future therapy or surgery.  In her opinion, as further elaborated in a letter opinion dated June 21, 2005, the employee’s 1998 injury was a strain and a mechanical injury to the low back, but the sustaining feature of the injury was shortening of the psoas muscles that prevented him from gaining lumbosacral extension and kept him in a forward bent position.  This, she opined, predisposed the employee to significant back problems.  She considered the 1998 injury a significant contributing factor to the employee’s chronic and ongoing pain and disability.  She further considered the December 2001 injury a significant factor.  Finally, she opined that his flare up of pain in October 2004 was also due to continuing to work as a school bus driver in a seated position, with an already injured back.

Dr. Chiasson stated that a CT myelogram would be needed to determine if any disc material was in the foraminal space.  However, as no CT scanner available would accommodate the employee’s size, it would be necessary to wait for this until he had weight loss.  She noted that he would need to wait about a year for gastric bypass surgery.  In her view, he should remain off work until his weight was lowered sufficiently for CT studies, so that she noted he would be off work for at least a year.

An administrative conference on the discontinuance was held on May 24, 2005.  Following the conference, the judge issued an order on discontinuance on May 26, 2005, permitting the employer to discontinue temporary total disability benefits.  The employee filed an objection to discontinuance on July 13, 2005, resulting in a hearing before a compensation judge on August 25, 2005.  The compensation judge found that the employee’s work injuries were not a substantial contributing cause of his inability to work after May 24, 2005, and allowed discontinuance.  The employee appeals.

The employee argues in his appeal that the compensation judge erred in rejecting the opinion of Dr. Chiasson and in adopting instead the opinion of Dr. Thomas. The employee claims Dr. Thomas’ report provides no “foundation, rationale, medical analysis, or explanation” for his opinion and should not have been accepted as the basis for the compensation judge’s decision. We disagree.

Dr. Thomas saw the employee in 1999 and again in 2005. He examined the employee, took a medical and vocational history from the employee, and reviewed the employee’s medical records, which Dr. Thomas identified as consisting of more than 350 pages. We conclude Dr. Thomas had adequate foundation to render an opinion.  Scott v. Southview Chevrolet, 267 N.W.2d 185, 188, 30 W.C.D. 426, 430 (Minn. 1978); Smith v. Quebecor, 63 W.C.D. 566 (W.C.C.A. 2003).
The question of the doctor’s rationale or analysis goes to the weight to be given the opinion rather than admissibility. Here, Dr. Thomas referred to the employee’s lack of radiculopathy, absence of objective findings, his failure to respond to therapy and medication, and the fact that there was no specific injury in October 2004 associated with the increase in symptoms as being factors in his conclusion.

The compensation judge in this matter was faced with two conflicting, well-founded medical opinions on the question of whether the employee’s work injuries were a substantial contributing factor in the employee’s ongoing disability. Determining which of those opinions to accept is uniquely within the province of the compensation judge. Nord v. City of Cook, 360 N.W. 2d 337, 37 W.C.D. 364 (Minn. 1985).

In addition to Dr. Thomas’ opinion, the medical records generally, as well as the prior opinion of Dr. Thomas in 1999, and the opinion of Dr. Boxall in 2002, support the conclusion that the employee’s 1998 and 2001 work injuries were in the nature of low back strains, from each of which he subsequently recovered.  These records are consistent with the view of Dr. Thomas that the employee’s pre-existing degenerative disc disease and obesity thereafter continued to be the sole source of his low back difficulties.

Finally, the employee argues that the compensation judge’s findings contravene the principle that a work-related aggravation of a pre-existing condition is compensable.  He contends that the compensation judge unfairly created an exception for obesity by denying compensation where the employee’s obesity in combination with work-related factors resulted in disability.  We disagree.  This contention simply misstates the compensation judge’s findings.  The judge did not find that the employee’s work activities combined with pre-existing obesity to cause the employee’s current symptoms.  Instead, the judge adopted the opinion of Dr, Thomas and determined that the employee’s work injuries were not related to his current symptoms and that the employee’s disability was due solely to his obesity.

We affirm.