The employer and insurer appeal from the compensation judge’s finding that the employee’s personal injury was a substantial contributing cause of her current disability.  We affirm.

Lois Wegner [the employee] sustained an injury to her right knee on May 18, 2008, arising out of and in the course of her employment with American Legion Post 50 [the employer], then insured by Auto-Owners Insurance Company.  The employer and its insurer admit that the employee sustained a personal injury on that date but contend that the injury was only temporary.

The employee has worked as a bartender for American Legion Post 50 in Wabasha, Minnesota since 1986.  On May 18, 2008, the employee was working alone when one of the beer kegs ran dry.  She testified that, after going to the basement to tap a new keg, she was running up the stairs when her knee buckled outward and she fell.  The employee testified that she sat for a few minutes, got up, hobbled up the steps, and finished her shift.  She testified that, as the shift went on, her knee kept became more swollen, and she experienced pain around the knee cap running up into the middle of her thigh.

The employee received treatment for her right knee prior to her personal injury.  In September 2004, she was seen at the Wabasha Clinic complaining of right knee pain for the past month.  An x-ray was normal, and Dr. Angstman diagnosed degenerative joint disease.  In September 2004, the employee gave a history of right knee pain when walking, and she stated that she felt it wanting to buckle or give out when going up and down stairs.  Physical therapy was ordered, which did not improve the employee’s condition.  An MRI scan of the right knee in September 2004 showed mild chondromalacia and degenerative signal changes in the posterior horns of both the medial and lateral menisci.  In October 2004, the employee was examined by Dr. Harry Robinson, at which time she was using crutches and was off work.  The doctor injected the employee’s right knee with lidocaine and ordered a bone scan, which proved normal.  Dr. Robinson stated he found no specific muscloskeletal orthopedic pathology to explain the employee’s pain.  In November 2004, Dr. Angstman’s assessment remained neuropathic knee pain, and the doctor kept the employee off work.  By December 2004, the doctor noted the employee was improved and was not using crutches or a brace and had no buckling of the knee.  The employee returned to see Dr. Angstman on March 1, 2005, complaining of some recurrence of pain, but the employee was not wearing a knee brace or using crutches.  The doctor’s examination was unchanged, and his assessment remained persistent neuropathic right knee pain.  Thereafter, the employee received no further treatment for her right knee until her May 18, 2008, personal injury.

On June 11, 2008, the employee saw Dr. Matthew Eich at the Lake City Medical Center.  The employee gave Dr. Eich a history of the incident at work and her current symptoms.  The doctor’s initial assessment was an internal derangement of the right knee consistent with a tear of the medial meniscus or a possible tear of the quadriceps tendon.  Dr. Eich ordered an MRI scan of the right knee, which showed no meniscal or ligamental tear.  Dr. Eich reviewed the MRI scan and found it to show a defect in the quadriceps tendon just above the patella, which correlated with his findings on examination.  His diagnosis was right knee strain with minimal quadriceps tendon strain.  In September 2008, the doctor ordered physical therapy.  In November 2008, the doctor performed arthroscopic surgery on the employee’s right knee.  His post-operative diagnosis was internal derangement of the right knee with a large pedunculate fibrous flap anterior medial corner, minimal chondromalacia of the tibial plateau, and a mildly attenuated anterior cruciate ligament.  The employee returned to see Dr. Eich for a follow- up evaluation in December 2008.  The doctor noted the employee was found to have “a pedunculated fibrous fat-pad that was impinging in the medial anterior compartment with kissing lesion.  Otherwise, the knee was quite normal inside.”  (Pet. Ex. D.)  By report dated July 20, 2009, Dr. Eich opined the employee had reached maximum medical improvement [MMI] in February of 2009, having sustained no permanent partial disability as a result of her work-related injury.

The employee returned to see Dr. Eich in January 2010 complaining of persistent pain in her right knee.  The doctor referred the employee to Dr. Suzanne Hecht at the University of Minnesota Medical Center, whom the employee saw on March 9, 2010.  On examination, Dr. Hecht noted tenderness over the quadtendon and the medial femoral condyle and recommended an injection of Synvisc One.  Dr. Hecht further stated an ultrasound might be needed to further assess the quadtendon, since that was the worst area of the employee’s pain.  Dr. Hecht stated she would keep the employee off work until October to further clarify the situation.  Finally, the doctor recommended a repeat MRI scan.

Dr. Randall Norgard, an orthopedic surgeon, examined the employee on July 15, 2010, at the request of the employer and insurer.  The doctor obtained a history from the employee, reviewed her medical records, and conducted an examination.  The doctor diagnosed right distal lateral quadriceps tendon pain and status post right knee arthroscopy with debridement.  He opined the employee had sustained a right knee strain and sprain as a result of her work activities on May 18, 2008.  The doctor noted the employee was experiencing problems which might be related to her injury, but the diagnosis was still unclear.  Dr. Norgard recommended another MRI scan with emphasis on evaluation of the quadriceps tendon.

In July 2010, the employee’s counsel wrote a letter to Dr. Eich and Dr. Hecht, summarizing the employee’s medical treatment from August 18, 2004, through April 28, 2010, and soliciting opinions from the doctors.  By letter dated August 12, 2010, Dr. Hecht stated that the employee’s diagnosis was probable quadriceps tendonopathy versus chronic knee pain of unclear etiology.  The doctor opined the employee’s work injury was a substantial contributing factor in the cause, acceleration, or aggravation of the employee’s knee condition.  Dr. Hecht stated the employee was not able to work at her current job due to her chronic knee pain.  The doctor recommended a new right knee MRI scan because she felt the quadriceps tendon had not been adequately evaluated.  Dr. Eich did not respond to the letter.

An MRI scan of the employee’s right knee was obtained on August 23, 2010.  The scan showed the menisci and ligaments were intact and demonstrated mild chondromalacia of the medial femoral condyle with adjacent reactive subchondral change and a trace of TCL bursitis.  The employee returned to see Dr. Hecht on August 25, 2010.  The doctor reviewed the MRI scan and detected some signal changes in the quadriceps tendon that were not referenced in the radiologist’s report.  The doctor asked a musculoskeletal radiologist at the University of Minnesota to review the employee’s MRI for a second opinion, concluding that an ultrasound might also be required to further assess the quadriceps tendon.  Dr. Hecht continued to restrict the employee from working.

In an office note dated September 2, 2010, Dr. Hecht asked her staff to help her to “get an approval for a diagnostic and possible therapeutic injection by musculoskeletal ultrasound of Ms. Wegner’s knee by her Workmans’ Comp. insurance?  It is to further assess her quadriceps tendon which the increased signal intensity and slight thickening on interpretation of her outside MRI by the UM MSK radiologists and this fits which [sic] some of her symptoms.”  (Pet. Ex. E.)

Dr. Norgard reviewed the August 2010 MRI scan and the office notes from Dr. Hecht and issued a supplemental report on September 27, 2010.  The doctor noted evidence of chondromalacia on the MRI scan but opined this condition pre-existed the employee’s personal injury.  His diagnosis was right knee medial compartment chondromalacia.  The doctor opined the employee had sustained a right quadriceps tendon strain on May 18, 2008, which had resolved, and he concluded that the employee had reached MMI from her personal injury as of August 25, 2010.  Dr. Norgard opined the employee needed no further medical treatment, imposed no restrictions, and rated no permanent disability due to the personal injury.

The employee filed a claim petition seeking temporary total disability benefits from September 29, 2010, and continuing, rehabilitation services, and payment of medical treatment recommended by Dr. Hecht.  Following a hearing, the compensation judge found no anatomical explanation for the employee’s current right knee pain, found the employee was unable to work as a bartender by reason of her personal injury, and found the employee was entitled to the medical treatment recommended by Dr. Hecht, together with rehabilitation assistance.  The employer and insurer appeal.

The compensation judge found the anatomical explanation for the employee’s current right knee pain was undetermined.  The employee had a history of significant right knee problems prior to her personal injury, and the appellants assert the employee’s current complaints are very similar to her past complaints.  The employee’s pre-existing history, together with the medical uncertainty as to the cause of her condition, the appellants argue, compel a conclusion that the employee failed to establish a causal link between the May 18, 2008, work incident and her current unexplained condition.  Dr. Eich, Dr. Hecht, and Dr. Norgard all agree the employee has right knee chondromalacia.  The appellants assert this condition pre-existed the personal injury.  Both Dr. Eich and Dr. Hecht have suggested the possibility of some sort of quadriceps tendon injury as the source of the employee’s ongoing pain complaints.  The appellants argue this theory is unsupported by the evidence.  Dr. Eich made no mention of any structural problems with the quadriceps tendon following his exploratory surgery in November 2008, and the August 2010 MRI scan of the right knee showed no evidence of any structural damage to the quadriceps tendon.  Accordingly, the appellants contend the compensation judge’s decision is unsupported by substantial evidence and must be reversed.  We disagree.

The fact that the anatomical explanation for the employee’s current right knee pain is undetermined is not a bar to compensability.  Compensability has been found for disability resulting from various diseases of unknown cause, such as Goodpasture syndrome, see Boldt v. Jostens’ Inc., 261 N.W.2d 92, 30 W.C.D. 178 (Minn. 1977), primary biliary cirrhosis, see Pommeranz v. State, Dep’t of Public Welfare, 261 N.W.2d 90, 30 W.C.D. 174 (Minn. 1977), and cancer, see Pittman v. Pillsbury Flour Mills, 237 Minn. 517, 48 N.W.2d, 35, 17 W.C.D. 15 (1951).  The issue in such cases is not the diagnosis of the employee’s condition but whether that condition was caused, aggravated or accelerated by the employee’s work.  Id. al.  Questions of medical causation fall within the province of the compensation judge.  Felton v. Anton Chevrolet, 513 N.W.2d 457, 50 W.C.D. 181 (Minn. 1994).

Dr. Eich reviewed the June 2008 MRI scan and found that it showed a defect in the quadriceps tendon just above the patella which correlated with his findings on examination.  The doctor diagnosed a quadriceps tendon tear or strain.  Nearly two years later, Dr. Hecht noted the employee continued to have tenderness over the quadriceps tendon.  In her August 12, 2010, letter, Dr. Hecht stated her diagnosis was probable quadriceps tendonopathy vs. chronic knee pain of unclear etiology, and she concluded that the employee’s work injury was a substantial contributing factor in the cause, acceleration, or aggravation of the employee’s knee condition.  There is substantial evidence of record supporting the compensation judge’s finding of a causal connection between the employee’ knee condition and her work injury.

Dr. Hecht’s causation opinion was rendered prior to reviewing the results of the August 23, 2010, MRI scan of the employee’s knee.  The appellants contend the doctor was therefore disqualified from rendering a credible opinion because she lacked complete information.  The appellants argue only Dr. Norgard had the benefit of the most recent MRI prior to rendering an opinion on causation.  Accordingly, the appellants contend the compensation judge erred in adopting the causation opinion of Dr. Hecht.  We are not persuaded.

Dr. Hecht consistently noted on examination tenderness in the area of the quadriceps tendon, which she concluded was consistent with quadriceps tendonopathy.  This remained Dr. Hecht’s diagnosis on August 12, 2010, when she recommended a repeat MRI scan.  Dr. Hecht reviewed the August 23, 2010, MRI scan and concluded it showed signal changes in the quadriceps tendon.  The doctor requested the follow-up MRI scan be reviewed by radiologists at the University of Minnesota, and they interpreted the scan as showing increased signal intensity and a slight thickening of the quadriceps tendon.  This reading of the MRI scan is consistent with Dr. Hecht’s diagnosis.  We find no lack of foundation for the doctor’s opinion based upon the August 23, 2010 MRI scan.

Finally, the appellants contend Dr. Hecht lacked adequate foundation to render a causation opinion because the employee failed to advise the doctor of her pre-existing knee problems.  The appellants point to Dr. Hecht’s March 9, 2010, chart note, which states the employee’s past medical history is unremarkable.  Accordingly, the appellants contend the compensation judge erred in relying on the opinion of Dr. Hecht.  We disagree.

In July 2010, the employee’s counsel wrote Dr. Hecht summarizing the employee’s medical treatment from August 18, 2004, through April 28, 2010.  See Pet. Ex. F.  Information contained in this letter provided Dr. Hecht with sufficient medical background to provide a causation opinion.  The competency of a witness to provide expert medical testimony depends upon the witness’ scientific knowledge and practical experience with the issue that is the subject of the offered testimony.  Reinhardt v. Colton, 337 N.W.2d 88, 93 (Minn. 1983).  Dr. Hecht was aware of the employee’s pre-existing medical history, obtained a history of symptoms and complaints from the employee, and performed medical examinations.  We have stated on many occasions that this level of knowledge about the subject matter affords adequate foundation for a doctor to enter an expert medical opinion.  See Drews v. Kohl’s, 55 W.C.D. 33, 38-39 (W.C.C.A. 1996).  The decision of the compensation judge is, therefore, affirmed.