The self-insured employer appeals from the compensation judge's finding of primary liability for a work injury, from the judge’s award of permanent partial disability benefits, and from the judge’s denial of apportionment for a preexisting condition.  We affirm.

In January of 2003, Shannon Tabbert [the employee] became employed as a resident aid with Hammer Residences, Inc. [the employer], a group home for physically and/or mentally disabled adults.  The employee was twenty-four years old at the time of his hiring and had a history of intermittent back and hip and leg complaints dating back to his childhood, the most recent being complaints of back and bilateral leg pain after weightlifting in October 2001 and January 2003.  Back x-rays on January 22, 2003, were read to reveal significant disc degeneration at L4-5 and particularly at L5-S1, but the employee was able to work without any specific back-related work restrictions, and he was not taking any related medications at the time he was hired.  The employee apparently underwent some related physical therapy in the spring of 2003, and in the summer of 2004 his low back symptoms reappeared, pursuant to which he was seen for treatment at the Twin Cities Spine Center, where an MRI scan was ordered.  The scan was conducted on June 16, 2004, and was read to reveal moderate to advanced disc degeneration at L4-5 and L5-S1, with some diffuse posterior bulging and mild to moderate stenosis at both levels, but no nerve impingement or herniation.  In follow-up two days later, on June 18, 2004, Dr. Ensor Transfeldt noted a history of low back symptoms “for about nine years,” with the pain particularly worse over the past year, predominantly in the back rather than in the leg at a ratio of 90% to 10%, and frequently more severe on the left than on the right.  On a diagnosis of “[a]dvanced disc degeneration L4-5 and L5-S1, associated with discogenic back pain,” Dr. Transfeldt recommended a regimen of anti-inflammatory medications, trunk strengthening and spine stabilization exercises, and good body mechanics.  He also “strongly” recommended continued conservative treatment, surgery being a possible option only “[i]f, down the road, he continues to have severe disabling pain, affecting the quality of life in even light activities.”  The employee had no further reported treatment for his low back after that for nearly fourteen months.

On the morning of Sunday August 7, 2005, the employee was seen at the Methodist Hospital emergency center, where the attending physician, Dr. Andrew Bachman, reported “a past medical history significant for chronic recurrent back pain,” concluding that the employee was presenting with “a typical back pain exacerbation.”  Dr. Bachman indicated that the employee reported that “he does lift weights including heavy weights that do strain his back, but his last weight lifting episode was one week ago” and he “denies any new trauma or injury.”    Dr. Bachman reported also that the employee did report “increased mid-low back pain . . . occurring throughout the day yesterday with associated ‘stiffening’ sensation,” which overnight had worsened.  The employee was reporting his pain to be at a level seven or eight on a scale of one to ten and on the right side, with occasional sensations to the lateral aspect of the right thigh, but no lower extremity numbness, weakness, or tingling, no constant lower extremity symptoms, and no left lower extremity symptoms.  Dr. Bachman administered morphine and two other medications, which reduced the employee’s pain down to a level two, he prescribed a Medrol Dosepak for radicular symptoms, ibuprofen for baseline pain, and Vicodin and Valium as needed for breakthrough pain and muscle relaxation, respectively, and he recommended follow-up with a primary care physician within a week.  On August 7, 2005, the employee was twenty-six years old, and the employer was self-insured against workers’ compensation liability.  The employee was seen again at the Methodist Hospital emergency center two weeks later, on August 21, 2005, with complaints that his back pain had at first subsided after August 7, 2005, but had now grown quite severe again.  He reported also that he was now experiencing radiculopathy symptoms, including numbness, down into his right foot, and the attending physician ordered an MRI scan through Dr. Transfeldt’s office.

Two days later, on August 23, 2005, the employer completed a First Report of Injury referencing a work injury to the employee on “8/13/05,” while the employee was earning a weekly wage of $337.50.  The report indicates that the employee first informed his supervisor of the injury on August 14, 2005, the day after it had reportedly occurred.  The injury is described on the report as having occurred as the employee “was working overnight & during the night was in extreme pain (back).  He attributed it to 2 clients hanging on his arms for support for several hrs during a family picnic earlier that day.”

The employee underwent his MRI scan on August 25, 2005, which was read to reveal, in addition to advanced chronic disc degeneration at L4-5 and L5-S1 and chronic mild foraminal stenosis at L5-S1, a large, extruded disc herniation and large disc fragment at L4-5 that was compressing the thecal sac and the L5 nerve sleeves.  The examining radiologist expressly noted the disc herniation to be “a new finding when compared to the June 16, 2004 study.”  Records of the employee’s follow-up examination by Dr. Transfeldt the following day, on August 26, 2005, indicate that the employee had begun experiencing right leg pain about three weeks earlier, had been tripping and catching his feet, had been to the emergency department twice, and was now under medication.  Those same records also reiterate the MRI findings of a disc herniation at L4-5 impinging on the L5 nerve root, and they report confirmation of that diagnosis by clinical findings.  The records continue, however, to reference no trauma or injury as the cause of the employee’s condition.  Finally, the records indicate that the employee had been prescribed an epidural steroid injection and was to remain on conservative treatment, with decompression surgery to be considered only if he did not show satisfactory improvement.  The employee received his injection on August 31, 2005, subsequent to which he reported 99% improvement within thirty minutes.

On September 6, 2005, Dr. Transfeldt reported - - the first such report by a doctor -  - that the employee’s current symptoms began at work on August 6, 2005, as the employee was supporting two mentally handicapped patients who were hanging onto him as he lifted one of them over the curb on a sidewalk in the course of his employment.  Because of what he described as “persistent weakness and pain,” Dr. Transfeldt recommended at that time that the employee proceed with decompression surgery, but by November 1, 2005, the employee’s pain symptoms had subsided to only “a few times a week” and were “not persistent,” and Dr. Transfeldt elected to continue with conservative treatment and perhaps another epidural steroid injection.

On November 18, 2005, the employee filed a claim petition, alleging entitlement to various medical and rehabilitation benefits, attorney fees, and out of pocket expenses, all consequent to a work injury on August 6, 2005.  The petition alleges a weekly wage of “at least $360.00 per week” and describes the nature of the injury as a “low back L3-4 [sic] herniated disc.”

On January 24, 2006, the employee saw Dr. Transfeldt again with complaints of recurrent right leg pain.  Upon finding no clear-cut signs of nerve root tension and no clear-cut objective motor weakness, Dr. Transfeldt recommended another epidural steroid injection at L4-5, with follow-up on an as-needed basis, and he released the employee to work within certain lifting and other spine-related restrictions.

On March 22, 2006, the employee was examined for the employer by orthopedic surgeon Dr. William Akins, who concluded in his report on that date, based in part on earlier reports in the employee’s medical records, that the employee did not sustain any work-related injury on August 6, 2005.  Dr. Akins noted that pain consequent to a disc herniation “is generally generated by chemical reactions that in some cases may take as long as two, three or four days to develop,” indicating that that fact was important in this case in that, at the emergency room on August 7, 2005, the employee mentioned his last weight lifting session one week earlier but denied any new trauma or injury until after August 26, 2005.  Dr. Akins found certain physical restrictions to be appropriate and most of the employee’s medical treatment to have been reasonable and necessary, but he found neither the restrictions nor the treatment to be causally related to any work injury.  Finally, noting that the employee’s leg pains had subsided, he concluded that the employee was subject to a permanent partial disability of 10% of his body as a whole, referable, however, only to his preexisting lumbar condition.

On September 29, 2006, the employee underwent another lumbar MRI scan, which was read to reveal some resorption of the extruded disc fragment that had been revealed in the right L4-5 nerve root canal on the employee’s August 25, 2005, scan.  About a month later, in a letter to the employee’s attorney dated October 24, 2006, Dr. Transfeldt acknowledged that the employee had had lumbar disc degeneration prior to his claimed work injury of August 6, 2005.  He opined, however, that the alleged injury of August 6, 2005, appeared to have been a significant aggravating factor in the employee’s low back condition, in that a subsequent MRI scan had revealed a large disc herniation and, whereas he had had no radicular leg pain prior to that injury, the employee had had persistent leg pain ever since that time.  The doctor went on to report that the employee had also had “quite significant foot drop weakness” since his alleged injury, although the severity of the leg pain had diminished and the right leg strength appeared to have improved, there having been, by MRI evidence, “considerable resorption, although not complete resorption, of the disc herniation.”

On November 2, 2006, Dr. Transfeldt completed a Health Care Provider Report, on which, under a diagnosis of lumbar disc degeneration and herniation, he rated the employee’s permanent partial disability at 13% of the whole body pursuant to Minnesota Rules 5223.0390, subparts 4E and 4E(1), consequent to a lumbar work injury on August 6, 2005.

The matter came on for hearing on December 8, 2006.  Issues at hearing were (1) whether the employee had sustained a work-related injury on August 6, 2005, in the nature of a disc herniation at L4-5, (2) the extent of any permanent partial disability sustained by the employee as a result of such a work injury, and (3) the reasonableness and necessity of certain medical treatments and their causal relationship to the employee’s work on August 6, 2005.  In his opening statement, the employer’s attorney contended that, even if the judge should find a work injury on the date alleged, and even if he should find the employee subject to a 13% whole-body permanent partial disability, “at most he would get 3 percent, the difference between [Dr.] Transfeldt’s [13%] rating and the [10%] rating from our physician” for the employee’s preexisting condition.  The employee  testified at hearing in part that, at the time of his alleged injury, he briefly experienced a hot, knife-like pain in his low back, which subsided a few minutes later, together with some difficulty breathing.  He testified further that he called a coworker about his injury in the wee hours of August 7, 2005, and then his supervisor about the injury later that morning, to advise him that he was going to the emergency room.  He noted also in his testimony that, whatever date of injury may have been written down by the employer on the First Report of Injury about two weeks later, the mechanism of injury identified in that report was clearly referencing events at the employer’s picnic for its clients, which as a matter of calendar record occurred on August 6, 2005.  He testified that he didn’t initially report the picnic incident or any immediately accompanying pain to his doctors because he had often experienced low back pain in the past and, as he had testified in his deposition, was still “generally trying to connect the dots” and “just wanted the [pain] to stop.”

By findings and order filed February 13, 2007, the compensation judge concluded in part (1) that the employee had sustained a work-related injury on August 6, 2005, as alleged, (2) that he had sustained a 13% whole-body permanent impairment as a result of that injury, and (3) that the medical expenses at issue were reasonable, necessary, and causally related to that injury.  The judge made no actual finding as to statutory apportionment for any preexisting condition, but he did address the subject in some detail in his memorandum.  The employer appeals from the finding of primary liability and from the award of permanent partial disability benefits.^[1]

In reviewing cases on appeal, the Workers’ Compensation Court of Appeals must determine whether “the findings of fact and order [are] clearly erroneous and unsupported by substantial evidence in view of the entire record as submitted.”  Minn. Stat. § 176.421, subd. 1 (1992).  Substantial evidence supports the findings if, in the context of the entire record, “they are supported by evidence that a reasonable mind might accept as adequate.”  Hengemuhle v. Long Prairie Jaycees, 358 N.W.2d 54, 59, 37 W.C.D. 235, 239 (Minn. 1984).  Where evidence conflicts or more than one inference may reasonably be drawn from the evidence, the findings are to be affirmed.  Id. at 60, 37 W.C.D. at 240.  Similarly, “[f]actfindings are clearly erroneous only if the reviewing court on the entire evidence is left with a definite and firm conviction that a mistake has been committed.”  Northern States Power Co. v. Lyon Food Prods., Inc., 304 Minn. 196, 201, 229 N.W.2d 521, 524 (1975).  Findings of fact should not be disturbed, even though the reviewing court might disagree with them, “unless they are clearly erroneous in the sense that they are manifestly contrary to the weight of the evidence or not reasonably supported by the evidence as a whole.”  Id.

At Finding 18, the compensation judge concluded that the employee sustained a work-related injury as claimed on August 6, 2005.  The employer contends that that conclusion is unsupported by substantial evidence in light of medical records contemporaneous with the time of the employee’s alleged injury, as referenced in the expert medical opinion of Dr. Akins.  It notes that records in the emergency department on the day following the alleged date of injury describe the employee’s low back condition as chronic and recurring and his current problem as only a “typical back pain exacerbation.”  Moreover, the employer argues, on that same date the employee himself denied any new trauma or injury, “even in the context of a discussion of his employment” (underscoring in original).  At two different examinations about two weeks later, the employer argues, the employee again gave no history of recent trauma or injury at work.  Moreover, it argues, the employee’s own testimony, credited by the judge, is internally inconsistent, in that at hearing he testified that he experienced sudden, burning, stabbing, knife-like back pain at the time of his alleged injury, whereas only a few hours later in the emergency room he did not connect his current symptoms with any such pain.  The employer argues further that the employee’s current version of the injurious event is that it occurred as a consequence of two clinging clients suddenly tripping over a curb, whereas the First Report of Injury indicates that the injury resulted from two clients hanging on his arms “for several hours.”  We are not persuaded.

That the employee has for much of his life experienced recurrent low-back-related problems arguably chronic is not at issue.  What is at issue is whether the employee’s current, post-August 6, 2005, problems are identical with or directly consequent to those preexisting problems.  The employee suggested in his testimony that he had grown accustomed to flare-ups in his back symptoms, and, given the fact that the particularly hot stabbing sensations at the picnic were evidently quite fleeting, it was not unreasonable for the employee himself, and so for the attending emergency room physician, to initially associate the August 7 symptoms with the preexisting condition.  Although even already at the emergency room on August 7, 2005, the employee’s symptoms were on the right rather than on the left, where they had mostly been in the past, it was not until two weeks later, on August 21, 2005, that the employee recognized and reported his symptoms to be more clearly radicular.  Two days thereafter, on August 23, 2005, the employer itself filled out a First Report of Injury on which it indicated that a new injury to the employee had occurred at the employer’s picnic, as ultimately concluded by the employee, and that the employee’s supervisor had been informed of that injury the day after it occurred.  That the report that the injury had happened at the work picnic did not become part of the medical record until September 6, 2005, is not at all critical in light of the employer’s First Report of Injury.  Nor does it seem to us of much consequence that that earlier report of the employer had the two clients clinging to the employee longer than the employee’s later testimony would suggest, given the reports’ basic agreement over the fact of the picnic as the place and the client support as the mechanism of injury.  We conclude that the compensation judge’s finding of causation by work activities was not unreasonable in light of the evidence, and so we affirm that finding.  See Hengemuhle, 358 N.W.2d at 59, 37 W.C.D. at 239.

At Finding 22, the compensation judge concluded that the employee sustained a 13% permanent partial disability to the body as a whole as a result of his work injury on August 6, 2005–10% for radicular pain or paresthesia pursuant to Minnesota Rules 5223.0390, subpart 4E, and an addition 3% for those symptoms’ being chronic and persistent despite treatment, pursuant to Minnesota Rules 5223.0390, subpart 4E(1) .  The employer contends that that rating of the employee’s low back condition is unsupported by substantial evidence in the first place and that, even if that overall rating were deemed to be correct, a 10% rating is assignable to the employee’s preexisting low back condition, rendering the employee’s compensable rating only 3% at most, after apportionment pursuant to Minnesota Statutes section 176.101, subdivision 4a.  We are not persuaded.

Minnesota Rules 5223.0390, subpart 4E, requires that, in order to qualify for any award under that subpart, an employee must demonstrate in part “objective radicular findings” there defined as “reflex changes or EMG abnormality or nerve root specific muscle weakness in the lower extremity,” together with correlating radiographic evidence of nerve root impingement.  Minn. R. 5223.0390, subp. 4E (underscoring added).  The employer contends that the employee is not entitled even to the initial 10% threshold rating provided for under that subpart, in that “there is no EMG/NC study, abnormal or otherwise” and Dr. Transfeldt, having earlier reported significant strength in the employee’s right leg, was now reporting even better strength.  We note, however, that Dr. Transfeldt, in his report on October 24, 2006, clearly indicated that the employee had “actually had quite significant foot drop weakness” (underscoring added) in his right leg, which he reported merely to have “improved” since the “not complete” resorption of the employee’s disc herniation.  Given the continuing very substantial radicular-like pain symptoms in the employee’s right leg, together with MRI evidence of evidently continuing disc herniation at L4-5, we conclude that the compensation judge’s rating of a 10% whole body impairment under Minnesota Rules 5223.0390, subpart 4E, was not unreasonable.

In his opening statement, counsel for the employer asserted that any permanent partial disability to which the employee was found to be subject relative to his low back was subject to apportionment under Minnesota Statutes section 176.101, subdivision 4a, in light of a preexisting low back condition rateable as a 10% whole-body impairment under the rules, in keeping with the expert medical opinion of Dr. Akins.  The compensation judge did not address any apportionment issue in his findings per se, but in his memorandum he explains that, under Minnesota Rules 5223.0390, subpart 3,^[2] under which Dr. Akins rated the employee’s preexisting lumbar pain syndrome as a 10% whole-body impairment,

Having concluded that the judge’s rating of a 10% whole-body impairment under Minnesota Rules 5223.0390, subpart 4E, was not unreasonable, noting that the employer does not apparently contest the added 3% rating for persistence of symptoms despite treatment under subpart 4E(1) of that rule, having concluded also that the judge’s denial of apportionment under Minnesota Statutes section 176.101, subdivision 4a, was also not unreasonable, and having affirmed the judge’s conclusion that the injury here at issue is work-related, we affirm the compensation judge’s award of compensation for permanent partial disability to 13% of the employee’s body as a whole.  See Hengemuhle, 358 N.W.2d at 59, 37 W.C.D. at 239.