The employee appeals from the compensation judge’s denial of payment for medical and chiropractic expenses incurred between August 20, 2007, and March 24, 2008.  We reverse.

Renee Hodge was an employee of Pro Staff, the employer, and was assigned to production work at Boston Scientific.  On August 14, 2007, the employee was working on the overnight shift moving stents to and from ovens and a rotating carousel.  While working, the employee was seated on a rolling chair with wheels.  She was required to wear a scrub gown, hat, and booties that covered her shoes.  At some point, a bootie got caught on a wheel while the employee was getting up from the chair.  The employee fell forward onto a concrete floor, landing on her knees and jolting her low back.  The employee reported the injury to her supervisor and went home in the early morning.

On August 16, 2007, the employee went to the Hennepin County Medical Center (HCMC) emergency room at approximately 10:30 p.m.  A nurse noted acute chronic back pain exacerbated by a fall at work.  When advised there would be a wait, the employee left and went to the emergency room at North Memorial Robbinsdale, arriving about 11:00 p.m.  The employee was seen by Dr. Thomas Rossini who noted tenderness to palpation in the mid-lower back and in the paraspinous muscles bilaterally.  Dr. Rossini diagnosed a low back strain and provided percocet for pain, a muscle relaxant, and ibuprofen.  The doctor stated the employee could return to work on Monday and advised her to follow up at the NorthWorks clinic.

The employee, instead, sought care on August 22, 2007, from Carson Benjamin, a chiropractor, who treated the employee for a thoracic and lumbar strain/sprain.  Dr. Benjamin referred the employee to the Noran Neurological Clinic where she was initially seen by Dr. Susan Evans on September 17, 2007.  On examination, the doctor noted low back muscle spasm and reduced flexion.  Dr. Evans diagnosed a lumbar strain, prescribed pain medications, a muscle relaxant, and an epidural steroid injection, and recommended continued chiropractic care.  An MRI scan on September 21, 2007, showed multilevel disc degeneration.  The employee was eventually referred to the Institute for Low Back and Neck Care where she was seen by Dr. Bryan Lynn on December 17, 2007.  Dr. Lynn recommended physical therapy for the next four weeks and prescribed a trial of Ultram for pain.

On March 24, 2008, the employee was examined by Dr. Mark Friedland at the request of the employer and insurer.  Dr. Friedland noted the employee had a pre-existing history of low back problems and stated the MRI scan findings were consistent with chronic and longstanding multilevel lumbar degenerative disc disease.  In his report, Dr. Friedland stated, “assuming that Ms. Hodge in fact did injure her low back as a result of the incident on 8/14/07, it would be my opinion that she sustained a lumbosacral strain/sprain.  It is further my opinion that this lumbosacral strain/sprain was temporary in nature.”  The doctor opined the employee reached maximum medical improvement (MMI) as of March 24, 2008, with respect to the low back injury, and the to-date medical care and treatment received by the employee was reasonable and necessary, except that chiropractic care should have been limited to twelve weeks.  (Resp. Ex. 3.)

In a letter report dated September 4, 2008, Dr. Evans provided a diagnosis of a lumbar strain with a disc herniation at the L5-S1 level, and opined the employee’s injuries were permanent and causally related to the personal injury.  It was Dr. Evans’ opinion that the employee would require further care, including continued chiropractic care and physical therapy, as well as future doctor visits for treatment of her low back injury.

The employee filed a claim petition seeking wage loss benefits and payment of medical and chiropractic expenses.  The employer and insurer denied primary liability, disputing the employee’s claim that she injured her low back at work on August 14, 2007.  The case was heard by a compensation judge at the Office of Administrative Hearings on December 4, 2008.  At the hearing, counsel for the parties stipulated that if primary liability was found, medical care and treatment up to March 24, 2008, and twelve weeks of chiropractic care prior to that date were reasonable and necessary.  (T. at 8.)  In a Findings and Order issued on March 2, 2009, the compensation judge found the employee did sustain a personal injury to the low back on August 14, 2007,^[1] but the injury was a temporary aggravation from which the employee had recovered by the following Monday.  The judge further found that the employee reached maximum medical improvement as of April 23, 2008, when served with Dr. Friedland’s report; that the medical care at HCMC and North Memorial on August 16 and 17, 2007, was reasonable, necessary, and causally related to the work injury; and that the work injury was not a substantial contributing cause of the employee’s need for care after August 20, 2007.  The employee appeals.

The employee argues that once the compensation judge found primary liability, that is, that the employee did, in fact, sustain an injury to her low back at work on August 14, 2007, the parties’ stipulation automatically removed from the judge’s purview the compensability of medical and chiropractic treatment up to March 24, 2008.  We disagree.

Primary liability in a workers’ compensation case refers to the employer’s liability for the original injury itself.  In primary liability disputes, the question is whether the injury arose out of and in the course of the employment.  Medical causation is a concept distinct from primary liability that addresses the connection between the personal injury and a subsequent condition, that is, whether the condition treated was medically related to the original injury.  Jackson v. Red Owl Stores, Inc., 375 N.W.2d 13, 17-18, 38 W.C.D. 170, 177-78 (Minn. 1985).

To be compensable, medical treatment must be both reasonable and necessary and causally related to the injury.  While the parties stipulated to the reasonableness and necessity of the treatment provided to the employee up to March 24, 2008, there was no agreement that the treatment rendered was causally related to the personal injury.  The judge, therefore, properly addressed the issue of whether the employee’s work injury was a contributing cause to the employee’s need for the treatment claimed.  Under these circumstances, we find no basis to vacate the compensation judge’s findings.

The compensation judge found that the employee sustained a temporary aggravation of her low back on August 17, 2007;^[2] that the employee had recovered from the temporary aggravation by the following Monday; that the employee reached maximum medical improvement effective April 23, 2008; and that the work injury was not a substantial contributing cause of the employee’s need for care after August 20, 2007.  (Finding 15.)  The employee argues the judge’s findings are not supported by substantial evidence and are clearly erroneous.  We agree.

In making her determination, the judge cited Dr. Rossini’s release to return to work the Monday following the employee’s emergency room visit on August 16-17.^[3]  A release to return to work is not necessarily the equivalent of “recovery” from a personal injury.  To state the obvious, ongoing symptoms and continuing medical care or treatment and a release to return to work are not mutually exclusive circumstances.  At the time of the visit, Dr. Rossini noted findings of tenderness to palpation on examination, diagnosed a low back strain, provided pain medication, muscle relaxants, and ibufrofen, and advised the employee to follow up at Northworks clinic.  We cannot read this record as evidencing “recovery” from the personal injury.

The compensation judge found Dr. Friedland’s opinions persuasive, and relied upon the doctor’s opinions in finding the employee sustained a temporary aggravation to the low back on August 14, 2007.  (Finding 13.)  The employer and insurer cite Nord v. City of Cook, 360 N.W.2d 337, 37 W.C.D. 364 (Minn. 1985) for the proposition that it is the compensation judge’s responsibility, and not this court’s, to resolve conflicts in medical expert testimony.  We agree the compensation judge could properly rely upon the opinions of Dr. Friedland in this case.  There is, however, nothing in Dr. Friedland’s report from which one could conclude the employee had fully recovered by August 20, 2007.^[4]  Instead, Dr. Friedland opined that the employee reached MMI with respect to her low back strain/sprain as of March 24, 2008, based on her objectively normal examination on that date.  “Maximum medical improvement” means the “date after which no further significant recovery from . . . a personal injury can reasonably be anticipated.”  Minn. Stat. § 176.011, subd. 25.  While not expressly stated, Dr. Friedland’s MMI opinion is consistent with the conclusion that the employee recovered from her temporary aggravation by March 24, 2008.  Compare Kautz v. Setterlin Co., 410 N.W.2d 843, 40 W.C.D. 206 (Minn. 1987)(where an employee has completely recovered from a personal injury, MMI is irrelevant.)

Both Dr. Evans and Dr. Friedland opined the employee’s medical care and treatment for the low back was reasonable and necessary, at least up to March 24, 2008, as reflected in the parties’ stipulation.  At the hearing, the employer and insurer focused on primary liability issues, contending the employee had long-term, pre-existing low back problems, that no injury occurred on August 14, 2007, and that the employee was not credible.  The respondents did argue, in the alternative, that if there was an injury, it was a temporary aggravation.  They made, however, no claim, contention, or argument that the temporary aggravation had resolved by August 20, 2007.  In fact, the respondents made no argument in particular with respect to the date by which the employee had recovered if primary liability was found, relying instead on Dr. Friedland’s reports.

While cognizant of this court’s standard of review on appeal, viewing the entire record as submitted, we can conclude only that the compensation judge’s finding that the employee’s work injury was not a substantial contributing cause of the employee’s need for medical treatment and care between August 20, 2007, and March 24, 2008, is unsupported by substantial evidence and clearly erroneous.  We, accordingly, reverse, and award payment of medical expenses in accordance with the stipulation of the parties.