The employee appeals from the compensation judge’s findings that the proposed anterior spinal fusion is not reasonable and necessary medical treatment and that the proposed surgery is not causally related to the employee’s personal injury.  We affirm in part and vacate in part.

Daniel R. Hill, the employee, sustained a personal injury on May 12, 2009, arising out of his employment with Beckeralla Investments, L.L.C., the employer, then insured by American Family Insurance Group.  The employer and its insurer admitted liability for a personal injury.

The employee first sought medical treatment for his injury on May 26, 2009, from Dr. John Kipp at the Stillwater Medical Group.  The employee gave a history of a sudden onset of central and right-sided back pain after lifting a stove at work on May 12, 2009.  The employee complained of persistent low back pain with occasional radiation to the right gluteal region with no other radicular symptoms.  The doctor ordered an MRI scan which showed a disc protrusion at L4-5 and a disc bulge at L5-S1 both of which appeared to be having a mass effect on the right L5 nerve root.  Dr. Kipp diagnosed a lumbar disc herniation with L5 radiculitis.

Dr. Bruce Bartie, an orthopedic surgeon, examined the employee in August 2011 on referral from Dr. Kipp.  The doctor recommended a right L4-5 microdiscectomy decompression surgery which he performed in September 2009.  The employee followed up with Dr. Bartie.  By December 2009, the doctor examined the employee and found he had full strength in his legs, full range of motion and no evidence of ongoing weakness or sensory change.  In January 2010, Dr. Bartie released the employee to work subject to restrictions on lifting and carrying.

The employee returned to see Dr. Kipp in February 2010 complaining of persistent low back pain with right and left leg numbness.  The doctor diagnosed a lumbar disc syndrome with bilateral leg pain and ordered an EMG to clarify the employee’s leg symptoms.  The EMG was indeterminate and the examiner stated the results might represent the earliest stages in development of a generalized peripheral neuropathy.  Dr. Kipp reviewed the EMG and noted the employee’s bilateral leg numbness did not follow a radicular pattern.  The doctor recommended a neurological examination and ordered another MRI scan which showed no evidence of a recurrent disc herniation but reflected annular fissures at L4-5 and L5-S1.

Dr. Donna Konig, a neurologist, examined the employee in March 2010 on referral from Dr. Kipp.  The doctor reviewed the March 2010 MRI scan and stated the employee’s neural foramen appeared open without evidence of impingement.  The EMG, Dr. Konig reported, showed no evidence of lumbosacral radiculopathy.  The doctor concluded the employee’s pain seemed more consistent with sciatic nerve irritation since it did not follow a radicular pattern.  Dr. Konig opined the employee would not benefit from a second surgery and referred him to Dr. Louis Saeger, an interventional pain specialist.  Dr. Saeger saw the employee in May 2010 and afterwards administered a series of lumbar epidural steroid injections that provided no subjective relief.

Dr. Wanda Blaylark, an occupational medicine specialist, examined the employee in June 2010 at the request of the employer and insurer.  The doctor opined the employee sustained a lumbar spine injury in May 2009 resulting in a disc protrusion which was successfully repaired with surgery.  The doctor opined the employee now had persistent low back pain due to degenerative disc disease and a chronic pain syndrome, both unrelated to his personal injury.  Dr. Blaylark stated that further physical therapy, injections or surgery were not reasonable or necessary and the employee should engage in a home exercise program.

During a four-day period from July 6 through July 9, 2010, the insurer obtained video surveillance of the employee for approximately five hours.  The video was condensed into twenty-five and one-half minutes and submitted without objection as an exhibit at the hearing.  The compensation judge found the video surveillance revealed the employee engaging in several activities involving bending, twisting, stooping, kneeling and squatting with no apparent distress.  The judge found the surveillance also showed the employee engaged in prolonged bending over while sitting on the porch of his house, walking briskly, bending over at the waist to pick up objects, and engaging in frequent bending, stooping, and squatting while detailing his motorcycle.  The judge found the employee engaged in all of these activities with what the judge characterized as a full range of motion with no observable back stiffness or recognizable pain behaviors.

On July 6, 2010, the employee saw Dr. Stefano Sinicropi at the Midwest Spine Institute with complaints of significant low back pain and bilateral leg pain.  On examination, the doctor noted the employee had only a fifty percent range of motion in all directions.  Dr. Sinicropi diagnosed spondylolisthesis at L4 on L5 with a two-level disc disruption at L4-5 and L5-S1.  The doctor ordered a lumbar discogram which he concluded was concordant at L4-5 and L5-S1 and demonstrated degeneration and annular disruptions at both levels.  The employee returned to see Dr. Sinicropi in November 2010.  Dr. Sinicropi then recommended an anterior spinal fusion at L4-5 and L5-S1 with possible instrumentation at L5-S1 and a minimally invasive posterior facet fusion with instrumentation at L4-S1.

In December 2010, the parties settled the employee’s workers’ compensation claim on a full, final and complete basis, leaving open claims for medical benefits.  An Award on Stipulation was served and filed January 5, 2011.

Dr. Mark Friedland examined the employee in December 2010 at the request of the employer and insurer.  By report dated January 17, 2011, the doctor concluded the employee’s May 2009 personal injury caused a right-sided L4-5 disc herniation injury which had been successfully surgically treated.  Dr. Friedland reviewed the surveillance video, opined the employee was able to move extremely well, and concluded the employee was voluntarily limiting movement when examined by his treating doctors.  He noted the March 2010 MRI scan showed no evidence of any significant segmental instability or spondylolisthesis.  Dr. Friedland stated the recent EMG demonstrated no evidence of residual lumbar radiculopathy but did show early peripheral neuropathy of both legs.  The doctor stated the employee was a habitual tobacco abuser which would be a contraindication for a fusion.  Dr. Friedland concluded the proposed anterior and posterior fusions at L4-5 and L5-S1 were not reasonable or necessary medical care.

Dr. Sinicropi reviewed the surveillance video of the employee and Dr. Friedland’s January 17, 2011, report.  By report dated May 11, 2011, the doctor again opined the employee’s back pain and his leg symptoms were due to a two-level disc disruption and spondylolisthesis of L4 and L5 along with foraminal narrowing at L4-5 and foraminal stenosis at L5-S1.  The doctor stated the surveillance tape showed the employee cleaning his motorcycle and car as well as opening and closing his garage door and noted the video was limited to about twenty-five minutes.  Dr. Sinicropi stated it was extremely common for patients with the employee’s condition to have good and bad days.  The doctor did not feel the surveillance video provided an overall view of the employee’s continuing abilities but only showed a very limited time period and did not obviate the need for the surgery he previously recommended.

Dr. Friedland reviewed the May 11, 2011, report of Dr. Sinicropi and disagreed with his observations about the surveillance video.  Dr. Friedland stated that if the employee was capable of the fluid movements of the spine without evidence of discomfort as shown on the surveillance video, he did not have sufficient symptomatology associated with his mild degenerative disc disease to warrant a two-level surgical lumbar fusion as recommended by Dr. Sinicropi.  Further, Dr. Friedland again opined the EMG study showed no evidence of lumbosacral radiculopathy.  In the absence of clinical symptoms consistent with a true lumbar radiculopathy and without EMG documentation of radiculopathy, Dr. Friedland opined an L4-S1 fusion was not appropriate.

Thereafter, the employee filed a Medical Request seeking approval for the fusion surgery recommended by Dr. Sinicropi.  Following a hearing, the compensation judge found that the proposed medical treatment was not reasonable and necessary and not causally related to the employee’s May 12, 2009, personal injury.  The employee appeals.

The compensation judge found the fluidity and range of the employee’s motion revealed on the surveillance video was inconsistent with a person experiencing significant back pain or a person needing a two-level fusion.  The judge further found the employee’s ability to move reflected on the surveillance video on July 6, 2010, was inconsistent with Dr. Sinicropi’s findings that same day that the employee only had fifty percent range of motion of the lumbar spine.  Based, in part, on the surveillance video, the compensation judge found the proposed surgery was not reasonable and necessary.  The employee contends the findings, observations, and conclusions drawn from the compensation judge’s review of the surveillance video are clearly erroneous and unsupported by substantial evidence.  He contends the video surveillance on July 6, 2010, was only three minutes in length, an insufficient time to be able to fully judge the employee’s physical abilities.  Further, the employee testified that he does the best he can to function within his limitations despite his pain and argues the surveillance video does not convey the severity of the symptoms he experiences every day.  For these reasons, the employee contends the conclusions drawn by the judge’s review of the surveillance video are erroneous and unsupported by substantial evidence.

The insurer obtained approximately five hours of employee activity in a surveillance video which was condensed into a twenty-five minute video synopsis.  The video synopsis was received into evidence without objection.  We acknowledge the compensation judge inaccurately stated the video showed the employee bending over for an hour detailing his motorcycle and inaccurately reported the dates of certain activities.  Nonetheless, the compensation judge did review the entire video and noted the employee engaged in several activities involving bending, twisting, kneeling and squatting with no apparent distress.  The compensation judge concluded the employee’s movements shown on the video were inconsistent with a person with incapacitating low back pain.  “Where more than one inference may reasonably be drawn from the evidence, the compensation judge's findings shall be upheld.”  Nord v. City of Cook, 360 N.W.2d 337, 342, 37 W.C.D. 364, 371 (Minn. 1985).  A finding based on the credibility of a witness will not be disturbed on appeal unless there is clear evidence to the contrary.  Even v. Kraft, Inc., 445 N.W.2d 831, 42 W.C.D. 220 (Minn. 1989).

If the surveillance video was the only evidence supporting the compensation judge’s decision, the employee’s arguments might well be more persuasive.  That is not, however, the case.  Dr. Mark Friedland examined the employee in December 2010.  In conjunction with his physical examination, the doctor obtained a history from the employee and reviewed his medical records, including the EMG study and the two MRI scans.  There is no dispute that Dr. Friedland had sufficient scientific knowledge and practical experience with the matter to afford him adequate foundation for his opinions.  Drews v. Kohl’s, 55 W.C.D. 33 (W.C.C.A. 1996).  The doctor found no objective radiographic evidence of any segmental spinal instability at either the L4-5 or L5-S1 levels.  Dr. Friedland concluded the proposed two-level lumbrosacral fusion was not reasonable or necessary medical treatment.  The compensation judge adopted Dr. Friedland’s opinion.  Although Dr. Sinicropi disagreed, it is the responsibility of the compensation judge as the trier of fact to resolve conflicts in expert testimony.  Nord, 360 N.W.2d at 342-43, 37 W.C.D. at 372-73.  Substantial evidence supports the compensation judge’s conclusion that the proposed surgery is not reasonable or necessary and that finding is affirmed.

The employee also appeals the compensation judge’s order that the proposed fusion surgery is not causally related to the employee’s May 12, 2009, personal injury.  In his opening statement, counsel for the employer and insurer stated, “the issue is whether or not the employee can prove that the proposed surgery recommended by Dr. Sinicropi is reasonable and necessary.”  (T. 9.)  Because causation was not raised as a defense, the issue was not properly before the compensation judge.  That portion of the judge’s order number 1, dealing with causal relationship is vacated.