The self-insured employer appeals from the compensation judge’s denial of apportionment of permanent partial disability benefits under Minn. Stat. § 176.101, subd. 4a.  We affirm.

Joel S. Rabideaux, the employee, began working for the self-insured employer, Minnesota Power, Inc., also known as ALLETE, Inc., in October 1990.  The employee had a significant preexisting low back condition that dated back to the mid-1980s and resulted in three surgical procedures.  The employee had his first low back surgery in September 1998, consisting of a laminotomy and disc excision at L3-4 with foraminotomy of the left L3 nerve root.  In February 1999, the employee experienced a recurrence of low back pain with bilateral leg pain and underwent a second surgery consisting of laminectomies at L3 and L4, an L3-4 discectomy, and foraminotomies of the L4 and L5 nerve roots.  In 2001, the employee underwent a third surgery consisting of bilateral laminectomies, facetectomies, and foraminotomies at L3 and L4, a left-sided discectomy at L3-4, and a posterolateral bilateral fusion at L3-4 with segmental bilateral instrumentation and placement of a bone stimulator.

On April 4, 2003, the employee sustained a personal injury to his low back arising out of his employment with the employer.  Following a hearing, a compensation judge found the April 4, 2003, injury substantially and permanently aggravated the employee’s preexisting low back condition.  The compensation judge further found the employee’s personal injury caused the need for a fourth low back surgery in the nature of a foraminotomy that resulted in no appreciable improvement in the employee’s condition, and the employee subsequently underwent the implantation of a morphine pain pump in February 2005.  In a decision served and filed October 31, 2006, this court affirmed the findings of the compensation judge (Rabideaux v. ALLETE, Inc., No. WC06-157 (W.C.C.A. Oct. 31, 2006)).

The employee subsequently filed a claim petition seeking payment of permanent partial disability benefits.  Following a hearing, the compensation judge found the employee was not entitled to any additional permanent partial disability as a result of the fourth low back surgery in 2004 or the implantation of the morphine pump.  The compensation judge found the employee has a 19% permanent partial disability of the lumbar spine but found the entire 19% preexisted the personal injury.  The compensation judge additionally found the April 4, 2003, personal injury was a substantial contributing cause of the development of bowel, bladder, and sexual dysfunction, motor and sensory loss in the lower extremities, and ataxia.  The judge further found the employee developed thoracic spine problems from the implantation of the morphine pump that aggravated a preexisting thoracic spine condition.  The compensation judge rated a 7% permanent partial disability of the thoracic spine, a 10% permanent disability related to the central nervous system and the spinal cord injury resulting in ataxia, a 12.5% permanent disability for motor loss in the lower extremities, a 20% permanent disability for bladder disorder, a 12% permanent disability for an anal disorder, and a 10% permanent disability for sexual dysfunction.  After application of the statutory formula,^[1] the compensation judge awarded the employee a 62.41% total permanent partial disability.  None of these findings are appealed.  The compensation judge found that except for the 19% permanent disability of the lumbar spine, no apportionment of permanent disability under Minn. Stat. § 176.101, subd. 4a, was appropriate.  The self-insured employer appeals this finding.

The self-insured employer contends the employee‘s current 62.41% permanent partial disability is due, in substantial part, to his preexisting low back condition and asserts this preexisting disability is clearly evidenced in a medical report or record made prior to the 2003 personal injury.  The appellant argues the compensation judge erred in failing to apportion some percentage of the awarded permanent partial disability to the employee’s preexisting disability and seeks reversal of the compensation judge’s denial of the requested apportionment.

For injuries occurring prior to January 1, 1984, there was no apportionment when the work injury aggravated or accelerated a non-work preexisting condition to produce a disability.  In Vanda v. Minnesota Mining & Mfg. Co., 218 N.W.2d 458, 27 W.C.D. 397 (Minn. 1974) the Supreme Court stated:

The law was changed by Minn. Stat. § 176.101, subd. 4a, effective January 1, 1984, which provides, in part:

Minn. Stat. § 176.101, subd. 4a, allows apportionment of permanent partial disability “only if the preexisting disability is clearly evidenced in a medical report or record made prior to the current personal injury.”  In unappealed findings, the compensation judge found the employee developed thoracic spine problems, bowel, bladder, and sexual dysfunction, motor loss, and a spinal cord injury as a result of the April 4, 2003, personal injury.  The employee had none of these conditions prior to his personal injury.  Thus, none of the 62.41% permanent disability awarded by the compensation judge for these conditions preexisted the employee’s personal injury.  Since none of the permanent disability which the appellant seeks to apportion preexisted the employee’s personal injury, it could not have been clearly evidenced in a medical report or record made prior to the personal injury.  Apportionment under Minn. Stat. § 176.101, subd. 4a, is not, therefore, available.

The appellant argues, however, that the words “preexisting disability” in the statute refer to any disability that preexists the personal injury and is a substantial and contributing cause of permanent disability which arises subsequent to the personal injury.  The employee had a low back condition rated at 30% permanent disability prior to his April 2003 personal injury.  This preexisting low back condition was, the appellant asserts, a substantial and contributing cause to the development of the conditions resulting in the 62.41% permanent disability.  Accordingly, the appellant contends apportionment of a portion of the permanency to the preexisting condition is appropriate.^[3]  We disagree.

By this argument, the appellant, in essence, seeks equitable apportionment of the 62.41% permanent disability awarded by the compensation judge.  In Minnesota, common law principles of equitable apportionment have long been applied to require successive employers and insurers each to contribute their proportionate share of the total responsibility for wage loss and permanent partial disability benefits.  DeNardo v. Divine Redeemer Memorial Hosp., 450 N.W.2d 290, 42 W.C.D. 626 (Minn. 1990); Stone v. Lakehead Constructors, 533 N.W.2d 36, 52 W.C.D. 637 (Minn. 1995).  This is not such a case.  Apportionment of permanent partial disability under Minn. Stat. § 176.101, subd. 4a, has nothing to do with the principles of equitable apportionment.  Equitable apportionment is not available to apportion to a non-work, preexisting disability an employer’s or insurer’s liability for permanent partial disability resulting from a personal injury.

The primary aim of apportionment under Minn. Stat. § 176.101, subd. 4a, is to “alleviate the burden on employers for that part of the permanent partial disability which is not related to a work injury.”  Fleener v. CBM Indus./Alexsis, Inc., 564 N.W.2d 215, 217, 56 W.C.D. 495, 499 (Minn. 1997).  The employee’s personal injury was a substantial and contributing cause of the development of the conditions for the 62.41% permanent disability awarded by the compensation judge.  Thus, all of the 62.41% permanent disability is related to the work injury.  Since statutory apportionment is not available in this case, the appellant is liable for the 62.41% permanent partial disability benefits awarded by the compensation judge.  The compensation judge’s decision is affirmed.