JUAN MENDEZ-MERINO, Employee, v. FARMSTEAD FOODS and ITT SPECIALTY RISK SERVS., INC., Employer-Insurer/Appellants, and MN DEP=T OF HUMAN SERVS., OWATONNA PHYSICAL THERAPY, ABBOTT NORTHWESTERN HOSP., OWATONNA HOSP., MN DEP=T OF LABOR & INDUS./VRU, TWIN CITIES SPINE CTR., and CONSULTING RADIOLOGISTS, Intervenors.

 

WORKERS= COMPENSATION COURT OF APPEALS

JUNE 11, 2002

 

HEADNOTES

 

CAUSATION - SUBSTANTIAL EVIDENCE; EVIDENCE - EXPERT MEDICAL OPINION.  The expert medical opinions of Dr. Pinto were adequately founded, and the com­pensation judge did not err in relying upon them in determining the employee=s work injury of October 15, 1992 was a substantial contributing cause of the employee=s subsequent wage loss and need for medical treatment.

 

Affirmed.

 

Determined by Johnson, C.J., Wilson, J., and Pederson, J.

Compensation Judge:  Harold W. Schultz II.

 

OPINION

 

THOMAS L. JOHNSON, Judge

 

The employer and insurer appeal the compensation judge=s finding that the em­ployee=s 1992 injury was a substantial contributing cause of his claimed wage loss and need for medical treatment.  We affirm.

 

BACKGROUND

 

Juan Mendez-Merino, the employee, worked as a laborer for Farmstead Foods, the em­ployer, insured by ITT Specialty Risk Services, Inc.  The employee worked in the hog cut department weighing and cutting meat.  Hog carcasses were moved to the assembly line on a hook and dropped onto a conveyer belt.  The employee aligned the carcass on the belt for cutting.  On October 15, 1992, a hog carcass fell off a hook onto the floor.  As the employee lifted the carcass to put it on the conveyor belt, he felt something crack in his lower back.  He testified he was in a lot of pain and he couldn=t turn.  The employee completed his shift that day.

 

The following day, an English-speaking friend of the employee called the employer and reported the injury.^[1]  The employee continued to work, but was assigned a light-duty job that did not require lifting.  Approximately a week after the injury, the employee went to Mexico because his father was ill.  When he returned to Minnesota, after a week or so, the employee was informed he no longer had a job with the employer­.

 

 On November 9, 1992, the employee sought treatment from Gary Mumaugh, D.C., com­plaining of constant low back pain since lifting a hog at Farmstead Foods appro­xi­mately 25 days before.  ­The employee also reported some right sacroiliac (SI) and sciatic pain.   Dr. Mumaugh noted restricted lumbar range of motion and tenderness in the lumbar spine area.  X-rays showed a marked decrease of the L5-S1 disc space.  The employee received eight chiropractic treatments to the low back and sacroiliac joints, through December 16, 1992, with some improve­ment.

 

The employee was seen by Dr. Joanne B. Rogin, on December 21, 1992 for a neuro­logical con­sultation on referral from Dr. Mumaugh.  The employee reported a worsening of his pain, but denied any lower extremity symptoms.  Mild lumbar spasm with decreased range of motion was noted on examination.  An EMG conducted by Dr. Rogin on December 28, 1992 was normal.  The employee was seen in follow-up at the Owatonna Clinic on December 30, 1992.  The doctor noted persistent back pain for two months with no significant radicular symptoms.  The doctor=s impres­sion was mechanical low back pain, and the employee was advised to use heat or ice and given an anti-inflammatory medi­cation.

 

The employee began treating with Frederick R. Smith, D.O., at the Albert Lea Regional Medical Group on January 4, 1993.  The employee reported a lot of low back pain without radiation into the hips or lower extremities.  Dr. Smith recorded tenderness and pain on palpation in the sacro­iliac area and diagnosed a lumbar strain/sprain.  The doctor prescribed Flexeril and an anti-inflam­matory and referred the employee for physical therapy.  The employee completed six therapy ses­sions during which he continued to ex­perience exacerbations of low back and sacroiliac pain.  The employee returned to see Dr. Smith on January 18, 1993.  An x-ray taken on that date revealed bilateral spondylolysis at L5.   Dr. Smith diagnosed a lumbar strain/sprain occurring on October 15, 1992 and pre-existing spondylolysis which he felt had little to do with the employee=s current back pain.

 

The employee returned to see Dr. Smith on April 1, 1993.  The employee had been in Mexico due to the death of his father, but was back in Owatonna and working at the turkey proces­sing plant in Faribault.  He reported continuing pain over the lower lumbar and upper sacral area, especially with bending or prolonged standing.  Dr. Smith prescribed medications and a back brace and referred the em­ployee for ad­ditional physical therapy.  He advised the employee he would likely have back pain off and on for the rest of his life.  By report dated April 26, 1993, Dr. Smith diag­nosed a lumbar strain/sprain oc­curring on October 15, 1992, with bilateral spondylolysis at L5 which was likely pre-existing but could have been aggravated by the work injury.  The doctor provided a perma­nent partial disa­bility rating of 3.5 percent, prescribed Amitriptyline and Darvocet, and im­posed moderate-duty work restrictions.   The employee continued to receive physical therapy through May 17, 1993.  On July 1, 1993, following a recheck examination, Dr. Smith stated the employee had reached maximum medical improve­ment (MMI), and reaffirmed the 3.5 percent permanency rating for a healed sprain/strain with rigidity and loss of motion.

 

The employee was examined on September 1, 1993 by Dr. Paul Cederberg at the request of the employer and insurer.  The doctor noted the employee was taking Darvocet or Motrin and had a lumbar support.  On examination, the employee reported localized tenderness over L5-S1 and was able to bring his fingertips to within one foot of the floor.  The doctor diagnosed a musculo­liga­mentous sprain of the lumbar spine, resolved.  Dr. Cederberg opined the employee had reached MMI, had a 0 percent permanency, and was capable of working without formal work restrictions.

 

The employee was next seen at the Owatonna Hospital emergency room on February 20, 1994 complaining of back pain and swelling of his feet and ankles at the end of the day.  He fol­lowed-up with Dr. Smith on February 22, 1994 reporting a major increase in his low back symptoms and swelling in his lower extremities.  The employee stated he was working at a hotel in the Twin Cities which required pushing a cart with cleaning and maintenance supplies.  On examination, the doctor noted restricted lumbar mo­tion and pain over the sacroiliac area.  Dr. Smith diagnosed an exacer­bation of the employee=s lumbar sprain/strain.  The doctor felt the swelling in the employee=s ankles was probably due to being on his feet for long periods of time and the leg symptoms likely did not have anything to do with his back injury.  The doctor saw the employee twice more, prescribing anti-inflammatories and physical therapy.

 

On April 11, 1994, Dr. Smith requested an MRI scan due to the employee=s con­tinuing low back pain.  The April 13, 1994 scan revealed dehydration, degeneration and rupture of the disc annulus at L5-S1 with a small, confined central/posterior herniation.  Bilateral spondy­lo­lysis at L5 with minimal subluxation was also reported.   Dr. Smith discussed the MRI scan and treat­ment options with the employee on May 3, 1994, including referral to the Institute for Low Back Care or to an orthopedic surgeon at the Orthopaedic and Fracture Clinic.  Physical therapy was discontinued as the employee did not seem to be getting long-term relief.  By report dated May 5, 1994, Dr. Smith revised his permanency rating based on the MRI scan findings, assessing seven percent for a healed strain/sprain with pain and rigidity associated with demonstrable degenerative changes, single verte­bral level, plus nine percent for a single vertebral level herniated disc, not surgically treated, for a total of 16 percent.

 

The employee began treating with Dr. Sunny S. Kim at the Institute for Low Back Care on May 23, 1994.  His chief complaint was chronic low back pain with a history of a work-related injury on October 15, 1992.  Based on the MRI scan, Dr. Kim diagnosed isthmic spondylo­listhesis, spondylolysis.  The doctor found restricted lumbar range of motion and localized ten­derness at L5-S1.  Dr. Kim noted the employee had received conservative care for about two years and raised the option of a spinal fusion.  On June 24, 1994, the employee advised Dr. Kim he did not want to have a fusion.  The employee returned to Dr. Smith on July 6, 1994, who concurred with this decision stating he believed surgery should not be considered until all else failed and the employee=s pain was signifi­cantly interfering with his life.

 

The employee had filed a claim petition on May 24, 1993, alleging a low back injury on October 15, 1992, and seeking wage loss benefits, permanent partial disability and rehabilitation assistance.  The parties entered into a Stipulation for Settlement in early July 1994, in which the employer admitted liability for a personal injury to the low back on October 15, 1992.   The em­ployee accepted a lump sum payment of $22,000.00 which included a closeout of wage loss benefits through January 1, 1999 and permanent partial disability to 15.37 percent, along with payment of various medical expenses.  Reasonable and necessary non-chiropractic medical expenses remained open.  An Award on Stipulation was served and filed on July 18, 1994.

 

On July 20, 1994, the employee was seen by Dr. Gordon Welke at the Orthopaedic and Fracture Clinic in Owatonna.  Dr. Welke examined the employee Abriefly,@ but deferred giving an opinion, stating he was generally biased against fusions.  The employee then saw Dr. Gene Swanson at the Orthopaedic and Fracture Clinic in Mankato on August 31, 1994.  The employee reported low back discomfort and occasional discomfort in his feet.  On exami­nation, the doctor noted limited forward flexion and localized discomfort over the L5 spinous process.  His impression was a pre-existing spondylolysis at L5 aggravated, but not initiated, by a work incident.  Dr. Swanson con­cluded the employee=s symp­toms were Acertainly real,@ but did not favor surgery given the rel­atively minimal nature of the symp­toms, and opined it would be more reasonable to control the employee=s symptoms by a change in occupational activities, avoiding heavy labor.

 

The employee was not seen by a doctor for eleven months, then saw Patrick Corrigan, RPA-C, at Dr. Kim=s office on July 31, 1995.  The employee stated he continued to work as a laborer and reported an increase in his low back pain over the last several weeks for which he was taking Flexeril.  Mr. Corrigan diagnosed an exacerbation of the employee=s low back strain and referred the employee for physical therapy.  The employee received nine physical therapy treatments reporting a 50 percent improvement.  On August 23, 1995 he returned to Mr. Corrigan who continued the physical ther­apy.  The employee completed six additional physical therapy treatments and was discharged from the program with a 70 percent improvement and instructions to continue his home exercise program.  The employee reported continuing low back pain when seen in follow-up by Dr. Kim on December 11, 1995.  Dr. Kim prescribed anti-inflammatory medication and again discussed the option of fusion surgery.

 

The employee did not see a doctor again until November 11, 1997 when he returned to Dr. Kim reporting lumbosacral pain with intermittent pain into both calves over the past year.  On examination, the doctor found restricted range of motion and tenderness in the lumbosacral area.  His neurological examination remained normal.  The employee was fitted with a new lumbar corset and given a prescription for pain medication.  Dr. Kim opined the employee=s pain was most likely due to the spondylolisthesis.  The employee was seen by Jay Ferguson, PA-C, in Dr. Kim=s office on January 5, 1998, again noting bilateral leg pain that had gradually worsened.  The employee was given anti-inflammatory medication, advised to wear his corset when working, and provided with home exercises.  On October 20, 1998, the employee was seen by Patrick Corrigan complaining of severe back pain.  On examination, range of motion was quite restricted with tenderness at the L5 facet joint radiating into the right flank.  The employee was neurologically intact. Anti-inflamma­tories and Flexeril were prescribed and the employee was referred for physical therapy.

 

The employee returned to see Dr. Kim on February 22 and March 25, 1999, with increas­ing low back and bilateral leg pain.  He told Dr. Kim he wanted to have surgery as he was tired of putting up with his pain and symptoms.  Dr. Kim requested a repeat MRI scan.  The March 25, 1999 scan showed degenerative disc desiccation and an annular tear with a small, central pos­terior pro­trusion at L5-S1 and spondylolysis at L5 with associated mini­mal anterolisthesis of L5 on S1.  On May 13, 1999, Dr. Kim recommended a posterolateral fusion with pedicle fixation based on a per­sistent painful spon­dylolisthesis complicated by an an­nular tear at L5-S1.

 

The insurer refused approval for the surgery and requested a second opinion.  The parties agreed upon Dr. Manuel Pinto.  The employee was examined by Dr. Pinto on July 14, 1999.  The doctor=s neurological examination was essentially normal and he found no evidence of stenosis on the MRI scan.  Dr. Pinto concluded the employee=s symptoms were likely discogenic with re­ferred pain to the legs and recommended a three level discogram.  The doctor indicated that if the disco­gram reproduced the employee=s symptoms, an anterior posterior fusion would be ap­propriate.  The discogram, performed on September 2, 1999 showed abnormal morphology with a posterior annular tear at L5-S1 and 10/10 concordant low back pain.

 

The employee was re-examined by Dr. Cederberg on September 30, 1999, at the request of the employer and insurer.  The doctor noted limited flexion and extension and a normal neuro­logical examination.  Dr. Cederberg diagnosed a resolved lumbar sprain/strain secon­dary to the em­ployee=s October 15, 1992 work injury, pre-existing spondylolysis at L5-S1, and degenerative disc disease at L5-S1.  Dr. Cederberg concluded the employee=s current condition was due to con­geni­tal spondylolysis and noted age-related degenerative changes at L5-S1 as well as pre-existing spondylo­listhesis.  He opined there was no evidence the work injury of October 15, 1992 caused any perma­nent aggravation of the employee=s condition and stated the work injury was not a substantial con­tributing factor to the spondylolysis/spondylolisthesis condition for which surgery was being proposed.

 

Although the insurer denied approval for the surgery, the employee decided to pro­ceed because he couldn=t stand the pain in his low back and legs any more.  The surgery, consisting of a discectomy at L5-S1, an anterior and posterolateral fusion at L5-S1 with instrumentation, and a laminectomy at L5, was performed by Dr. Pinto on June 28, 2000.  The employee testified his condition improved following the surgery.

 

Dr. Cederberg re-examined the employee following the surgery,­ on November 16, 2000.  The doctor reiterated his opinion that the employee=s complaints prior to the surgery were due to a pre-existing congenital spondylolysis at L5-S1.  In Dr. Cederberg=s opinion, the October 15, 1992 work-related lumbar strain was a temporary aggravation of the spondylolysis, and did not contribute to the need for the June 28, 2000 surgery.

 

By report dated December 14, 2000, Dr. Pinto agreed the employee had spondylolis­thesis/spondylolysis likely present for many years preceding the work injury, but noted the condition is most often asymptomatic.  Dr. Pinto stated the lumbar discography showed an extremely painful L5-S1 disc, indicating the majority of the employee=s symptoms resulted from a symptomatic lumbar disc and not the spondylolisthesis/spondylolysis.  Thus, the surgery was performed primarily to relieve the painful disc derangement at L5-S1, and treatment of the spondylolisthesis/spondylo­lysis was incidental.  In Dr. Pinto=s opinion, the work injury of Oc­tober 15, 1992 was a substantial contributing factor to the employee=s disability and need for surgical treatment.  He noted, first, that the employee was doing well prior to the injury.  He hypothesized that if the employee=s symptoms had resolved within a few weeks or months of the injury and only recurred many years later, he would feel the surgery was not causally related.  But, based on the employee=s treatment records, Dr. Pinto felt it was apparent the employee continued to have symptoms all along, requiring periodic medical care for persistent low back and leg symptoms.  He, therefore, opined the employee=s diag­nosis was, from the date of the injury, a symptomatic lumbar disc derangement and the source of his lumbar strain/sprain symptoms was the under­lying disc derangement.

 

The employee filed a claim petition on June 1, 2000, seeking temporary partial dis­ability benefits from March 8, 1999 to February 27, 2000, temporary total disability benefits from February 28, 2000 and continuing, payment of medical expenses, and rehabilitation assistance.  The employer and insurer admitted the employee sustained a personal injury to the low back on October 15, 1992, but denied any additional benefits were due.  The case was heard by a compensation judge at the Office of Administrative Hearings on January 4, 2001.  In a Findings and Order, served and filed on March 5, 2001, the judge found the October 15, 1992 personal injury was not a substantial contributing factor to the employee=s wage loss beginning in March 1999, and the need for medical treatment.  The employee appealed the compensation judge=s denial of benefits to the Workers= Com­pensation Court of Appeals.  In a decision filed August 7, 2001, this court vacated the compen­sation judge=s decision and remanded the case for redetermination based on the existing record.  In a Findings and Order on Remand, the compensation judge concluded the employee=s personal injury of October 15, 1992 was Aan aggravation of his pre-existing spondylolysis and a permanent injury to his L5-S1 disc diagnosed as a disc derangement.@  (Finding 48.)  The compensation judge further found the claimed wage loss and medical treatment were substantially caused by the admitted injury.  The employer and insurer appeal.

 

DECISION

 

In a medical report dated December 14, 2000, Dr. Pinto stated the employee had spon­dylolisthesis/spondylolysis which was present for many years before the October 15, 1992 personal injury.  However, the doctor opined the personal injury resulted in a lumbar disc derangement at L5-S1 which necessitated the fusion surgery.  The compensation judge adopted the opinions of Dr. Pinto and awarded benefits.  On appeal, the employer and insurer contend the employee=s 1992 injury was only a temporary aggravation of the employee=s pre-existing spondylolysis and was not a substantial contributing cause for the fusion surgery or the wage loss.  The appellants argue the opinions of Dr. Pinto to the contrary lack foundation and the compensation judge erred in adopting the testimony of Dr. Pinto.  We disagree.

 

The appellants first argue Dr. Pinto=s opinion lacks foundation because he erroneously assumed the October 15, 1992 injury resulted in continuing low back symptoms and flare-ups and erroneously assumed the work injury resulted in the development of back and leg pain.  They argue the employee=s treatment with Dr. Smith in February 1994 was caused by the employee=s work with a different employer and, following resolution of that flare-up, the employee went ap­proximately 13 months without any treatment.  Further, appellants assert the employee did not report symptoms of leg pain until 1994.  The appellants contend the evidence fails to support Dr. Pinto=s underlying assumptions, rendering his opinion without foundation and mandates a reversal of the compensation judge=s award of benefits.  We are not persuaded.

 

The employee first sought treatment on November 9, 1992 with Dr. Mumaugh and complained of constant low back pain since his October 15, 1992 injury.  In January 1993, the employee began treatment with Dr. Smith, with whom he continued to treat until May 1994.  During that time, the employee was prescribed physical therapy but testified his low back pain never went away.  In May 1994, the employee saw Dr. Kim complaining of chronic low back pain since his work injury.  Dr. Kim noted restricted range of motion and localized tenderness at L5-S1 and then presented to the employee the option of a spinal fusion, which he declined for fear of the risks of surgery.  Thereafter, the employee testified his low back pain gradually worsened Alittle by little.@  (T. 35.)  Ultimately, the employee testified his pain increased to the point where he could no longer stand it and returned to Dr. Kim to have surgery.  Prior to the surgery, the employee complained of pain in his back, legs, feet and heels.  (T. 37.)  Following the June 2000 surgery, the employee testified his back, leg and foot pain was gone.  Prior thereto, however, the employee testified he had no significant or lasting improvement in his pain since the injury.  He testified the first real relief he had from his back pain was as a result of the surgery.

 

The doctors agree the employee had spondylolisthesis/spondylolysis prior to his work injury.  The employee testified, however, he had no back complaints or problems prior to October 15, 1992.  The record supports a conclusion that the employee=s low back complaints originated on October 15, 1992 and continued thereafter.  Based, in part, on the employee=s history, Dr. Pinto concluded the employee sustained a disc injury on October 15, 1992, which necessitated the fusion surgery.  The employee=s trial testimony adequately supports Dr. Pinto=s opinions and the com­pensation judge could reasonably rely upon them.  While Dr. Cederberg opined the employee=s per­sonal injury was a temporary aggravation of his pre-existing condition, resolution of the causation issue is ultimately the compensation judge=s choice between conflicting medical opinions.  See Nord v. City of Cook, 360 N.W.2d 337, 37 W.C.D. 364 (Minn. 1985).   Dr. Pinto=s opinions were adequately found­ed and the compensation judge reasonably relied upon them.

 

The appellants next argue Dr. Pinto=s opinions were inadequately founded because he failed to review all of the employee=s medical records.  They contend Dr. Pinto considered only  the employee=s history, discograms, an MRI scan and Dr. Cederberg=s report.  In contrast, the appellants contend, Dr. Cederberg reviewed all of the relevant medical records which he enumerated in his medical report.  Accordingly, the appellants argue the opinions of Dr. Cederberg are better founded than those of Dr. Pinto and should have been adopted by the compensation judge.  Again, we disagree.

 

As a general rule, the competency of a witness to provide expert medical testimony depends upon the degree of the witness=s scientific knowledge and the extent of the witness=s prac­tical experience with the matter which is a subject of the offered testimony.  Reinhardt v. Colton, 337 N.W.2d 88, 93 (Minn. 1983).  In this case, Dr. Pinto obtained a history from the employee, con­ducted numerous examinations and reviewed the diagnostic studies.  Typically, this level of knowledge establishes a doctor=s competence to render an expert opinion.  See Grunst v. Immanuel-St. Joseph Hosp., 424 N.W.2d 66, 40 W.C.D. 1130 (Minn. 1988).  While Dr. Pinto may not have reviewed all of the employee=s medical records, we have repeatedly stated such failure does not necessarily render a doctor=s opinion without foundation.  Drews v. Kohl=s, 55 W.C.D. 33 (W.C.C.A. 1996).  In any event, the appellants do not state which medical records Dr. Pinto failed to review and why they were of such significance that review of these records was vital to the doctor=s opinion on causation.  Under these facts, we cannot conclude Dr. Pinto=s opinions lack foundation and the compensation judge=s reliance upon those opinions is affirmed.