The employee appeals from the compensation judge’s determination that the employee failed to prove that she sustained a work-related injury as the result of a fall at work on January 13, 2012.  Concluding the compensation judge applied an inappropriate legal standard for establishing a personal injury, we vacate and remand for reconsideration.

The employee, Ramiza Colic, was born in Bosnia and immigrated to the United States in 2000.  She began working for the employer, TCF Financial Corporation, in October 2007.  The employee worked in various positions in a number of different locations, and in June 2011, was promoted to assistant manager of sales in the Anoka, Minnesota office.

On Friday, January 13, 2012, as the employee was walking from the employer’s parking lot to the entrance of the building, she slipped on snow-covered grass and fell, landing on her right side.  She reported the incident to her supervisor, then went to the Anoka RiverWay Clinic.  A history was taken of low back pain with pain radiating down the right thigh beginning about 10 days previously, and a slip and fall on grass in front of the office building on her way to work that morning.  The employee reported pain in the right buttock, right knee, and right wrist along with right-sided low back pain.  On examination, there was pain on palpation of the L4-L5 spinous process and on the right laterally, as well as tenderness on palpation of the posterior superior iliac spine on the right side.  The diagnosis was work-related acute low back pain, and the employee was prescribed pain medication and referred to physical therapy.  She was to return for follow-up in two weeks.  A report of work ability was provided releasing the employee to return to work the next day with restrictions.

The employee’s supervisor, Tamara Christopher, testified she did not hear from the employee after she left that morning, so she telephoned the employee around 3:00 p.m.  Ms. Christopher stated the employee told her the doctor had given her restrictions and medication and that she would not be able to work for two weeks.  Ms. Christopher testified further that she never received a copy of the January 13, 2012, work ability report, nor did the employee report for work as scheduled on Saturday.

The employee agreed her back had been bothering her in early January 2012 and she had an appointment to see Wayne Pratt, a chiropractor, before the slip and fall occurred.  Dr. Pratt had treated the employee previously, in 2006, for a work-related injury to her neck and upper extremity, for which she was off work for about two weeks and received chiropractic treatment for about two months.  The employee also received treatment from Dr. Pratt in the fall of 2010.  At that time, she had pulled a coin bin at work and suffered an acute lumbosacral sprain/strain.  She was off work for two weeks, and continued chiropractic treatment for another month.

The employee received treatment from Dr. Pratt beginning on Monday, January 16, 2012.  Dr. Pratt recorded acute low back pain with radiating pain into the right leg posteriorly to below the knee.  He suspected a disc herniation and requested an MRI scan.  He diagnosed a lumbosacral sprain/strain with radiculitis and took the employee off work.  The February 16, 2012, MRI scan showed mild degenerative disc disease and disc bulging at L5-S1 with no evidence of neurological impingement.

On February 25, 2012, the employee was seen by Dr. David Dorn, at the Noran Neurological Clinic.  The employee reported she first noted some low back pain radiating into the buttocks and thighs the previous summer.  Then in January 2012, she slipped on some snow and landed on her right side.  Following that, she stated, she had a marked increase in her low back and leg pain, mostly on the right.  On examination, Dr. Dorn noted tenderness over the lumbar spine but no spasm.  Extension was limited to 50% of normal but the remainder of her lumbar range of motion was full.  Dr. Dorn’s impression was a history of a work-related injury in January 2012 with low back pain and limb pain.  He expected the employee would improve over time, and prescribed a trial of dexamethasone, an antiflammatory corticosteroid medication.

In a statement of continued disability completed on March 12, 2012, Dr. Pratt stated the employee had right-sided low back pain and right leg and gluteal pain.  Straight leg raising reproduced right leg pain, there was moderate spasm and palpatory tenderness at L4-5, right S1, and in the right gluteal/piriformis area.  He again diagnosed a lumbosacral strain/sprain with radiculitis, and referred the employee to Physicians’ Diagnostics & Rehabilitation (PDR).  The employee was seen by Lindsay Haugen, PA-C, for an initial evaluation on March 30, 2012.  Ms. Haugen noted some soft tissue irritation as well as spasm and strain in the low back and over the sacroiliac area, and diagnosed a sacroiliac strain/sprain, lumbosacral strain/sprain, and low back pain.  She felt the majority of the employee’s pain was related to her fall.  Participation in the MedX physical rehabilitation program was recommended, and the employee was taken off work.

The employee returned to the Noran Clinic on April 2, 2012.  Deborah Osgood, PA-C, conducted an examination noting tenderness in the lower lumbar spine, the right sciatic notch, and in the right sacroiliac joint.  She was without spasm and was nontender in the paraspinous lumbar muscles.  Lumbar range of motion showed very marked limitation of extension and a 50% decrease in right and left lateral flexion, but near normal forward flexion.  The neurological examination was normal.  The employee was advised to continue the PDR therapy program and to see Dr. Pratt as needed.

The employee returned to see Dr. Dorn on June 7, 2012.  She reported persistent back and buttock area pain, but stated she was perhaps 60% improved.  On examination, there was tenderness over the lumbar spine and upper buttocks with a mild amount of spasm.  Flexion was full but extension was limited to about 25% of normal.  The remainder of the examination was normal.  Dr. Dorn wondered whether, given the areas of tenderness, there might be some component of sacroiliac irritation playing a role.

The employee was discharged from the PDR program on June 25, 2012, after completing 24 visits.  She continued to report pain in her right buttock and low back pain with extension of her back.  On examination, she had full lumbar flexion but was mildly restricted with extension reproducing right low back pain.  She had point tenderness over her right L5-S1 facet area with palpable spasm in that area.  She was released to return to work with no formal restrictions other than using good body mechanics, change positions as needed, and a graduated return to work from a part-time to a full-time schedule.

The employee was seen in follow-up by Ms. Osgood, PA-C, on July 11, 2012, accompanied by her qualified rehabilitation counselor (QRC).  She continued to have pain in the low back going into the right buttock and down the right posterior thigh.  She had gone back to work, four hours a day as a teller, and was doing a pool exercise program.  On examination, the employee was tender in the the right sacroiliac joint, the right sciatic notch, and in the lower lumbar spine.  Range of motion was mildly limited in all directions.  The employee stated she wanted to try an injection, so a right sacroiliac joint injection was ordered for her sacroiliitis.  The injection was performed on July 25, 2012.

The employee was seen on August 1, 2012, by Dr. William Simonet, at the request of the employer and insurer.  By report dated August 7, 2012, Dr. Simonet noted the employee’s current symptoms were pain in her low back and right leg.  On examination, Dr. Simonet noted the employee was overweight and had nonspecific complaints of tenderness with no point tenderness and no muscle spasm over the lumbar spine area.  Lumbar range of motion was normal and her neurologic examination was normal.  Dr. Simonet’s diagnosis was nonspecific, nonradicular low back pain with minimal evidence of objective findings to explain her subjective complaints.  Dr. Simonet maintained the employee’s treatment records, including those of Dr. Pratt, PDR, the MRI scan, and the Noran Clinic, documented no objective evidence of an injury, and he concluded there was no evidence the employee had sustained any specific injury on January 13, 2012.

On August 13, 2012, the employee reported to Dr. Dorn that all of her right leg pain resolved for a couple of hours after the injection.  Then, she reported, it returned, and over the next few days got much worse with with more pain and numbness in the right leg.  On examination, there was tenderness over the lumbar spine and right sacroiliac area with a mild amount of spasm.  Extension was extremely limited due to pain, but the remainder of her lumbar range of motion was full.  Dr. Dorn was not certain why the employee had so much increased pain after the injection, and stated the intensity of the pain seemed more pronounced than he would have expected.  He further indicated that since her leg symptoms completely resolved for a period of time after the injection, it raised the question of whether the sacroiliac joint was indeed contributing to a lot of her pain.

The employee was last seen by Dr. Dorn on September 18, 2012.  She continued to report quite a bit of pain in the lower back radiating into the right buttock and thigh.  On examination, there was tenderness over the right sacroiliac area with a mild amount of spasm.  Internal rotation of the right thigh reproduced the pain in her right buttock.  Lumbar range of motion was full and straight leg raising was negative.

At his deposition on October 16, 2012, Dr. Dorn stated that his preliminary diagnosis, on February 25, 2012, was low back and leg pain.  By June 2012, he began wondering if there was some irritation of the sacroiliac joint.  He explained that people with sacroiliac irritation can have pain in the back, buttock, and tingling into the thigh or leg.  Another possibility, Dr. Dorn testified, was inflammation of the various muscles around the pelvic joint, including the piriformis muscle.  The doctor stated that rotation of the thigh stretches some of the tissues around the back and pelvic area, suggesting the pain is probably coming from that area around the hip or sacroiliac area or the muscles in the buttocks and pelvic area.  Dr. Dorn testified he believed the employee was injured when she fell at work on January 13, 2012, and sustained injuries to the low back and structures of the pelvic muscles and probably also the sacroiliac joint, based on the symptoms the employee reported which were consistent with that type of injury; her response to the sacroiliac injection with relief of pain for two hours; and her findings on examination.  Dr. Dorn agreed that pain is a subjective complaint, but stated his diagnosis was based on the employee’s history and the symptoms she reported, as is often the case in neurology, rather than anything he could see or measure, such as MRI or CT scan findings.

Dr. Simonet, at his deposition on October 17, 2012, again stated that in his review of the employee’s medical records he found no evidence of any objective clinical findings that would document any injury related to the January 13, 2012, incident.  He stated the employee had complaints of pain but no physical evidence of abnormalities.  Dr. Simonet further stated the employee was diagnosed with low back pain, “which frankly, is not really a diagnosis, but a description of symptoms.”  (Ex. 17 at 14.)  The doctor further testified that he did not consider limited range of motion or muscle spasm objective findings since they are based on pain complaints and are under the voluntary control of the patient.  Dr. Simonet reiterated that it was his belief, based on the lack of objective findings, “that the employee did not suffer any injury at all on January 13, 2012.  No temporary aggravation, no momentary injury, anything.”  (Ex. 17 at 35.)

The matter was heard by a compensation judge at the Office of Administrative Hearings on October 31, 2012.  The judge determined the employee had failed to prove that she suffered a personal injury arising out of her employment with TCF Financial Corporation as a result of the fall on January 13, 2012.  The employee appeals.

The compensation judge found that the employee failed to prove she sustained a personal injury within the meaning of Minn. Stat. § 176.011, subd. 16.  In the memorandum accompanying his findings and order, the compensation judge explained his reasoning as follows:

The employee argues the compensation judge applied an inappropriate evidentiary standard for proving the existence of a personal injury.  The memorandum does suggest the compensation judge felt that a specific diagnosis or diagnoses with objective findings was necessary to establish the existence of a personal injury.  While objective findings are necessary for a permanent partial disability rating, no such requirement is contained within the definition of a person injury found in Minn. Stat. § 176.011, subd. 16.  It is well established that the existence of a personal injury may be established based on an employee’s subjective complaints coupled with the opinion of a medical expert that the employee sustained a work-related injury or aggravation.  Moreover, a lack of a specific diagnosis or anatomical explanation for the employee’s symptoms is not a bar to compensability.  The issue is not the diagnosis of the employee’s condition, but whether it was caused, aggravated, or accelerated by the work incident.  House v. Heartland Homecare, No. WC12-5474 (W.C.C.A. January 28, 2013); Bogdanowicz v. Target Corp., No. WC12-5483 (Feb. 12, 2013); Brown v. State, Dep’t of Transp., 54 W.C.D. 60 (W.C.C.A. 1996).

In his memorandum, the compensation judge further commented that while Dr. Dorn believed there was a possibility of some sacroiliac irritation or possible inflammation of muscles around the pelvic joint, possibilities are not diagnoses.  The judge also stated that “Dr. Dorn[] . . . gives no real explanation as to how or why that pain exists.”  It is not necessary that a medical expert pinpoint the exact etiology of a disease or condition for the resulting disability to be compensable, nor is it necessary to provide an explanation for the mechanism of the injury or condition.  “It is well established that the truth of the opinion need not be capable of demonstration, that an expert is not required to express absolute certainty in the matter which is its subject, and it is sufficient if it is probably true.”  Bold v. Josten’s Inc., 261 N.W.2d 92, 94, 30 W.C.D. 178, 182.

While the choice between the conflicting opinions of medical experts is generally left to the discretion of the compensation judge, see Nord v. City of Cook, 360 N.W.2d 337, 37 W.C.D. 364 (Minn. 1985), in this particular case, where it appears the compensation judge may have applied an inappropriate legal standard for establishing the existence of a personal injury, we believe a remand is necessary.  The compensation judge’s findings and order is, accordingly, vacated and remanded for reconsideration.