The employee petitioned to vacate an award on stipulation filed March 25, 1991, based upon mutual mistake of fact or a substantial change in medical condition.  Finding the petitioner has established good cause to vacate the award, we grant the petition.

On November 20, 1989, Julie Bourgoin, the petitioner, sustained a Gillette^[1] injury to her low back while working as a laborer for Gillette Company, the self-insured employer.  The employee was diagnosed with grade I spondylolisthesis at L5-S1.  On May 11, 1990, the employee underwent surgery at L5-S1, performed by Dr. Francis Denis, which included anterior spinal fusion, posterior spinal fusion, foraminotomy, Steffee instrumentation, and bone grafting.  The employee had a good result from the procedure, but still experienced some symptoms in her low back and left leg.  In February 1991, the employee still had nuisance type pain in the left L5 nerve root distribution and her neurological examination was intact for all reflexes.

In 1991, the parties agreed to a full, final, and complete settlement with the exception of future medical expenses related to the work injury for a lump sum payment of $46,500.00.  An award on stipulation was served and filed March 25, 1991.  The employee worked full time for another employer from October 1991 through February 1996.

The employee was involved in motor vehicle accidents in October 1993 and March 1997.  In April 1997, she reported severe neck and low back pain.  There was no evidence of fractures in her lower spine or neck and no evidence of defects in the fusion.  The employee was able to work full time for a different employer from May 1996 through October 18, 1999, when she sustained an aggravation of her low back condition while lifting a heavy box at work.  An October 26, 1999, x-ray indicated that the employee had grade II spondylolisthesis of L5 on S1.

In April 2000, Dr. Denis opined that a fair amount of the employee’s radicular symptoms were coming from the L5-S1 foramen, under the fusion.  On July 25, 2000, the employee underwent a L5-S1 foraminotomy and removal of surgical hardware from the 1990 fusion surgery.  A January 27, 2001, x-ray indicated that the employee had grade I/II spondylolisthesis at the L5-S1 level.  The employee continued to experience severe pain in her low back and left leg.  An MRI indicated two small herniations on the right at T7-8 and T8-9.  After conservative therapy failed, the employee underwent an anterior spinal fusion, anterior decompression, and posterior spinal reconstruction of T2 to T12 on February 14, 2006.

On August 8, 2006, the employee was evaluated by Dr. Mark Engasser.  Dr. Engasser opined in his report that

In May 2007, the employee reported ongoing symptoms of thoracic and low back pain.  Further surgery was suggested, but the employee preferred to continue with pain management.  In a September 28, 2007, report, Dr. Denis noted that the employee was not going to undergo any further surgeries, and opined that the employee was not likely to improve and had reached maximum medical improvement.  He also opined that the employee’s 1989 and 1999 work injuries were substantial and permanent contributing factors to her back condition.

On April 26, 2011, the employee filed a petition to vacate the 1991 stipulation for settlement based upon a mutual mistake of fact or a substantial change in medical condition.  The employer filed an objection.

This court has jurisdiction to set aside an award on stipulation upon a showing of good cause.^[2]  “Cause” is limited to fraud, a mutual mistake of fact, newly discovered evidence, or a substantial change in medical condition since the time of the award.  We note that for petitions to vacate awards on stipulation entered into before July 1, 1992, it is not required to show that the substantial change in condition was clearly not anticipated and could not reasonably have been anticipated.^[3]  Vacation of awards on stipulation is allowed to assure compensation proportionate to the degree and duration of disability.^[4]  The employee seeks to vacate the 1991 award on stipulation on grounds that the parties made a mutual mistake of fact or that she has experienced a substantial change in medical condition.

To establish cause sufficient to justify vacating an award on the grounds of a change in medical condition, a petitioner must provide evidence of a substantial deterioration in the petitioner’s condition or significant additional disability since the time of the settlement and a showing of a causal relationship between the injury covered by the award and the petitioner’s present condition.^[5]  The petitioner’s change in condition is generally considered in the context of a change in diagnosis, a change in the employee’s ability to work, additional permanent partial disability, the necessity for more costly and extensive medical care than previously anticipated, a causal relationship between the injury covered by the settlement and the covered condition, and the contemplation of the parties at the time of the settlement.^[6]

The employee’s low back diagnosis has changed from grade I spondylolisthesis at L5-S1 at the time of the 1991 settlement to grade II spondylolisthesis at L5-S1 in 1999.  The employer argues that any change after the successful fusion surgery is not significant since there is no evidence that the fusion failed or was no longer solid, there is nothing indicating that the employee will require additional surgery, and that the change in grade of spondylolisthesis was not characterized as significant in any medical opinion.  We disagree.  The employee’s low back condition has deteriorated since the settlement.  Further, Dr. Engasser found that part of the need for the employee’s additional surgery to remove the fusion hardware in 2000 was due to the 1989 injury.  Dr. Denis opined that the employee’s 1989 work injury was a substantial and permanent contributing factor to her back condition.  We conclude that the change from grade I spondylolisthesis to grade II spondylolisthesis represented a significant change in the employee’s diagnosis.

The employer has admitted that there has been a change in the employee’s ability to work, therefore we view this factor as supportive of her petition.

The employee claims that she is entitled to additional permanent partial disability for the change in diagnosis from grade I spondylolisthesis to grade II spondylolisthesis at L5-S1.  The employer points out that there is no doctor’s opinion to support this additional permanent partial disability rating and argues that if an additional rating is warranted, it is not substantial.  At the time of the settlement, the employee was claiming 17.5% permanent partial disability for her single level fusion under Minn. R. 5223.0070, subp. 1.D.  The employee claims that she is now probably entitled to an additional 7% permanent partial disability rating for the grade II spondylolisthesis under Minn. R. 5223.0070, subp. 1.A.4(a).  That rule, however, applies to grade I spondylolisthesis without surgery.  Minn. R. 5223.0070, subp. 1.A.4(b) applies to grade II spondylolisthesis, but also without surgery.  The employee may be entitled to additional permanent partial disability for the additional surgery she underwent, but without a doctor’s opinion to support any additional rating, we conclude that this factor does not support the petition in this case.

The employee claims that her additional low back treatment and the 2000 surgery for fusion hardware removal at the L5-S1 level demonstrate the need for more costly and expensive medical care since the date of the stipulation.  The employer asserts that because future medical expenses were left open by the stipulation for settlement, this factor is of less weight.  We have previously noted that, even where medical benefits are left open, the need for more expensive medical care than anticipated remains useful evidence bearing on whether there has been a substantial change in an employee’s condition.^[7]

The employer also argues that the surgery to remove the fusion hardware in 2000 and other low back treatment were related to efforts to diagnose pain complaints which were found to be attributable to the employee’s thoracic spine condition.  The medical evidence on this issue is conflicting.  While Dr. Engasser opined that the employee’s thoracic condition was not related to her work injury, he also opined that a significant part of the need for the 2000 surgery was due to the original injury in 1989.  Dr. Denis opined that the employee’s 1989 work injury was a substantial and permanent contributing factor to her back condition.  We conclude that the additional treatment was significant and at least in part related to her work injury, and constitutes evidence of a substantial change in the employee’s medical condition.

The employer’s main argument is that the employee’s current condition and the need for most of the medical treatment since the stipulation are causally related to her thoracic condition and are not related to her 1989 work injury.   The employer argues that the additional treatment for the employee’s low back was not necessary since her symptoms were ultimately treated with a thoracic fusion.   Dr. Engasser, however, opined that a significant part of the need for the 2000 surgery was due to the original injury in 1989.  Dr. Denis also opined that the employee’s 1989 work injury was a substantial and permanent contributing factor to her back condition.  We conclude that the additional treatment was done to rule out possible causes of the employee’s pain, which was necessitated by the employee’s work-related low back injury, and therefore constitutes evidence of a substantial change in the employee’s medical condition.

At the time of the settlement, the parties expected the employee to return to work with restrictions.  The employee was able to return to work full time for another employer from October 1991 through February 1996.  The employee was able to work full time for a different employer from May 1996 through October 18, 1999, when she sustained an aggravation of her low back condition.  The stipulation does not contain any language that the employee understood the possibility of her injury worsening.  There is no evidence that the parties contemplated the consequences of the employee’s condition worsening, which supports the employee’s petition to vacate.

The employee’s change in diagnosis, change in ability to work, and need for more costly medical care that were causally related to the employee’s 1989 work injury and were not contemplated by the parties, all support the employee’s petition to vacate.  Concluding that the employee has shown good cause to vacate the award at issue, we grant the employee’s petition to vacate the 1991 award on stipulation on grounds that she has experienced a substantial change in her medical condition.  Because we are granting the employee’s petition to vacate the award on those grounds, we need not address her argument that she is entitled to vacation of the award on grounds that the stipulation at issue was based upon a mutual mistake.