The employer and Western National Mutual Insurance Company appeal from the compensation judge’s determination that she was precluded by the doctrine of res judicata from determining whether the employee’s injuries prior to December 2003 were permanent or temporary and therefore was precluded from apportioning any liability to those injuries.  We affirm in part, vacate in part, and remand in part.

This case is before the court following the issuance of a findings and order on  remand, and concerns multiple injuries to his neck and low back that Randall Manthei, the employee, sustained while in the employ of Layne Minnesota Company between 1996 and 2007.

The employee began working for Layne Construction, the employer, in October 1975, at age 19, and has been employed there since 1975 except for approximately two years between 1979 and 1981, when he farmed with his brother.  Between 1975 and until some point before December 2005, the employer was insured for workers’ compensation liability in the state of Minnesota by CNA Commercial Insurance (CNA).  As of at least December 18, 2005, the employer was insured for workers’ compensation liability by Western National Mutual Insurance Company (Western National).

The disputes on appeal arise from admitted and alleged injuries the employee sustained between 1996 and 2007 while working for the employer, including specific injuries sustained between 1996 and 2005, a minute trauma injury to his neck and low back that the employee claimed culminated on January 24, 2003, a minute trauma injury to his neck that culminated in disablement on May 4, 2004, and a minute trauma injury to his low back that culminated in disablement on April 10, 2007.^[1]  CNA insured the employer at the time of the employee’s injuries before December 2005; Western National insured the employer at the time of the employee’s December 18, 2005, and April 10, 2007, injuries.

During his years of working for the employer, the employee has worked as a crane operator, a groundsman, and a foreman crane operator, working at job sites in a five-state area, and performing jobs that involved significant physical activity.  The employee has continuously worked for the employer since 1981; he is one of the top two persons on the employer’s seniority list.  At some point between March 2000 and August 2002, the employee began working as a foreman or working supervisor.  That position included more supervisory and management work and less crane operation than he had performed in the past, although the employee spent at least 10 to 20% of his time performing physically demanding job duties, and, to the extent he was physically able to do so, he also performed the job duties of co-workers who missed work due to illness.

In addition to his work for the employer, the employee has also performed farming work on his family farm where he and his family reside.  In the past, he typically worked approximately 20 hours per weekend on his farm, but by August 2002, he eased up on both his farming activities and the heavy work for his employer due to his ongoing symptoms.

Between 1988 and 2005, the employee sustained multiple injuries to his low back and neck.  The employer admitted liability for those injuries, but contended that they were temporary in nature.  The medical records show that the employee also sustained an injury in the nature of a pelvic crush injury at some point before 1995.  In addition, the employee claims that he later sustained Gillette injuries to his neck and low back as a result of his work activities; the employer denied primary liability for any Gillette injuries.

The employee has received periodic chiropractic and medical treatment for his neck and low back since his first work injury in 1988 and following each of his work injuries.  He was ultimately diagnosed with degenerative facet disease at the L4-5 and L5-S1 levels and foraminal stenosis on the left disc at the L5 level causing left L5 radiculitis.  An MRI scan showed  disc herniations at two vertebral levels.  By December 2001, Dr. Robert Wengler diagnosed degenerative disc disease and small contained disc herniations at the C4-5 and C5-6 levels of the cervical spine, and grade 1 spondylolisthesis at the L5-S1 level with a central left-sided disc herniation.  Dr. Wengler determined that the employee had sustained 10% permanent partial disability to the whole body as a result of his neck injuries and 12% permanent partial disability as a result of his low back injuries, and concluded that the employee’s cervical and lumbar disc conditions resulted from “multiple episodes of subacute trauma sustained during the course of his activities as a heavy equipment operator.”

On June 6, 2002, the employee filed a claim petition, listing six injury dates between 1995 and 1999, and claiming entitlement to permanent partial disability benefits relative to his neck and low back, in addition to payment of medical and chiropractic expenses.  He continued operating a crane until he sustained an additional injury on November 5, 2002, when he fell off the track of a crane, landed on his low back, and either hit or jarred his neck.  He ceased operating the crane after that injury, but continued to work for the employer, on a lighter-duty basis.  The employee testified that his symptoms in his neck and low back were permanently worsened by this injury, and that he has experienced headaches, pain in his left arm and pain in his legs.  The employee also testified that he continued to work because of his financial obligations and because he enjoys his work, but that he eventually will need to quit or perform other work due to his medical condition and persistent symptoms.

Based on additional testing, including a cervical spine discogram conducted on February 28, 2003, Dr. Wengler advised that the employee was a candidate for anterior discectomy and interbody fusion at two levels of the cervical spine.  In April 2003, the employee obtained a second opinion from Dr. Jeffrey Dick, who recommended that the employee quit smoking and undertake a six-month walking exercise program, and that if his symptoms did not significantly improve after six months, then the employee would be a candidate for surgical treatment.  The employee followed that advice, but his neck and low back symptoms persisted.

On September 24, 2003, Dr. Wengler was deposed for purposes of presenting his testimony at a hearing scheduled for December 2003.  Dr. Wengler testified that the employee’s day-to-day activities as a heavy crane operator over the years, such as “bouncing around, the manipulating of the friction devices in the crane, [and] looking up and looking down,” contributed to the aggravation of his underlying disc disease.  Dr. Wengler opined that the employee sustained an ongoing Gillette injury due to his work as a heavy equipment operator.  Dr. Wengler recognized that the employee continued to work and therefore, as described by Dr. Wengler, was “continually subjected to Gillette phenomenon.”

By contrast, Dr. Stephen Barron, who examined the employee at the request of the employer and CNA, concluded that the employee’s injuries had all been  temporary in nature, and that the employee was not a candidate for cervical spine surgery, based on the results of his discogram and lack of objective findings on examination.

The employee’s claims were addressed at a hearing on December 30, 2003.  In dispute were claims related to injuries that occurred between 1995 and November 2002, as well as a claimed Gillette injury of September 24, 2003.^[2]  As part of his claims, the employee sought approval for cervical fusion surgery, based upon the medical opinions of Drs. Wengler and Dick.

On March 15, 2004, the compensation issued her findings and order, in which she denied the employee’s claims in their entirety, except for a portion of his claimed chiropractic expenses.  She found that the employee’s work injuries of April 5, 1996, January 13, 1999, and November 5, 2002, were temporary in nature.  The compensation judge also found that the employee had not sustained a minute trauma injury to his neck or low back on September 24, 2003.  The employee appealed from the original findings and order.  On April 4, 2004, while his appeal was pending, the employee underwent a two-level anterior cervical fusion at C4-5 and C5-6, performed by Dr. Wengler.

Following the employee’s appeal, this court issued a decision in which it vacated the original findings and order and remanded the matter to the compensation judge for reconsideration, including whether the employee sustained a Gillette injury as a result of his work activities, in view of all the medical evidence of record, including post-hearing medical reports submitted by the parties.  Manthei v. Layne Minn. Co., slip op. (W.C.C.A. Jan. 20, 2005).

On December 18, 2005, while the case was being considered on remand, the employee sustained an additional injury to his low back.  As he worked as a foreman, he fell about ten feet off a crane, landing on his right foot and then hitting the ground with his right side and low back.  Since that time, he has experienced back pain and right-sided radicular pain.  On January 11, 2007, the employee underwent a two-level discography, and underwent fusion surgery at the L5-S1 level on April 10, 2007.

During the litigation on remand, it became apparent that Western National, the insurer at the time of the employee’s December 2005 injury, should be joined to the case.  The employee filed an amended claim petition on August 28, 2006, to bring in Western National as a party and to claim that he sustained a permanent low back injury on December 18, 2005, work injury.  The employee later pled, in the alternative, that he also had sustained a number of specific injuries to his low back and, in addition, a Gillette injury culminating in disablement on either January 24, 2003, or April 10, 2007.  With respect to his neck, the employee claimed that one or more specific injuries were permanent and that he also had sustained a Gillette injury to his neck culminating in disablement on either January 24, 2003 or May 4, 2004.

On August 2, 2007, a hearing was held before the compensation judge.  Issues heard at that hearing included not only the issues remanded by this court, but also issues arising out of the employee’s work after 2003 including, but not limited to, the employee’s claimed minute trauma injuries  to his neck and low back that led to surgeries performed in 2004 and 2007.  Medical records and reports placed in evidence and considered at the hearing on remand included the records introduced into evidence at the December 2003 hearing, medical opinions issued since December 2003, and treatment records for care provided to the employee between January 2004 and August 2007.  Those records included  Dr. Barron’s December 2006 report following a re-examination in which he concluded that all of the employee’s specific injuries were temporary in nature and that the employee had not sustained Gillette injuries to his cervical or lumbar spine.  The evidence also included Dr. John Dowdle’s December 2006 report, issued following an independent examination request by the employer and CNA, in which he concluded that the proposed lumbar spine surgery  was reasonable and necessary.

Following the 2007 hearing and her review of the matter on remand, the compensation judge found that the employee sustained a minute trauma injury to his neck, as a result of his work, which culminated on May 4, 2004.  She also found that the employee sustained a minute trauma injury to his lower back, as a result of his work, which culminated on April 10, 2007.  The compensation judge concluded that CNA was 100% responsible for benefits, including medical expenses, arising out of the injury to the employee’s neck on May 4, 2004, and that Western National was 100% responsible for benefits arising out of the employee’s injury to his low back on April 10, 2007.  The compensation judge also denied the employee’s claim for payment for chiropractic treatment.

The compensation judge also determined that various specific injuries that the employee had sustained in the course of his employment with the employer were only temporary in nature and did not permanently contribute to his current neck and back condition.  She specifically found that the employee did not sustain a permanent injury to his low back on December 19, 1997, nor December 27, 1999. The compensation judge also concluded that she was precluded by the doctrine of res judicata from addressing the issue of whether one or more of the employee’s specific injuries predating the December 2003 hearing, including the employee’s injuries on April 5, 1996, January 13, 1999, or November 5, 2002, were temporary or permanent.

The compensation judge ordered that the following benefits be paid to the employee:

The employer and Western National, the insurer at the time of the employee’s December 2005 and April 10, 2007, injuries, appeal from the compensation judge’s findings that the employee’s injuries before December 2003 were temporary in nature; that the employee sustained a minute trauma injury to his lumbar spine that culminated on April 10, 2007; that the employee is entitled to payment for post-surgery temporary total disability benefits, permanency benefits and  medical expenses related to treatment for his low back, ordered to be paid by Western National; and that it was inappropriate to apportion liability for the employee’s low back condition between his earlier injuries and his April 10, 2007, injury.

The employer and Western National also appeal from the compensation judge’s determination that the doctrine of res judicata precluded her from assigning any liability to injuries occurring before December 2003.  They argue that it was legal error for the compensation judge to not consider, on remand, whether the employee’s injuries before December 2003 were temporary or permanent.  They contend that the evidence showed that all of the employee’s pre-2003 injuries to the employee’s low back were permanent and played a substantial contributing role in the employee’s need for surgery in 2007, and that equitable apportionment should be assigned among the pre-2003 injuries and the adjudicated April 10, 2007, injury.

At the outset of the hearing on August 2, 2007, the compensation judge listed multiple issues to be addressed, including whether the employee sustained temporary or permanent injuries to his low back on April 5, 1996, December 29, 1997, January 13, 1999, December 27, 1999, and November 5, 2002, when the employer was insured by CNA.  She also listed the issues of whether one or more of the employee’s specific and minute trauma injuries represented substantial contributing factors to the employee’s need for low back surgery on April 10, 2007, and, therefore, whether this was an appropriate case for apportionment of liability between the two insurers for medical treatment and loss of time from work on and after December 18, 2005.  Counsel for the parties concurred that those issues were to be addressed at the hearing.

The compensation judge’s findings contradicted the above listing of issues.  At Finding No. 9 of her October 12, 2007, findings and order, the compensation judge referred to her 2004 decision, stating that

The compensation judge was not precluded, by the doctrine of res judicata, from determining whether the employee’s pre-December 2003 injuries were temporary or permanent.  The doctrine of res judicata precludes litigation of issues and claims that were litigated and decided in an earlier decision.  See, e.g., Fischer v. Saga Corp., 498 N.W.2d 449, 450, 48 W.C.D. 368, 369 (Minn. 1993), citing 3 Larson, The Law of Workman’s Compensation § 79.72(f) (1992) (“Res judicata does not apply if the issue at stake was not specifically decided in the prior proceedings.”).  See also Westendorf v. Campbell Soup Co., 243 N.W.2d 157, 158, 28 W.C.D. 460, 460 (Minn. 1976).  Collateral estoppel is a form of res judicata whereby an initial judgment is conclusive in a subsequent suit, between the same parties, as to issues finally decided in the initial action.  Travelers Ins. Co. v. Thompson, 163 N.W.2d 289 (Minn. 1969).  Principles of res judicata are applicable in workers’ compensation proceedings.  See, e.g., Alexander v. Kenneth R. LaLonde Enters., 288 N.W.2d 18, 31 W.C.D. 407 (Minn. 1980); Abrahams v. University of Minn., Duluth, 61 W.C.D. 103 (W.C.C.A. 2001).

In our decision of January 20, 2005, we vacated the compensation judge’s entire March 15, 2004, findings and order, so all issues were open and were to be decided anew at the time of the 2007 hearing.  Although we earlier addressed and focused on three areas and issues for the compensation judge to reconsider, we vacated the entire 2004 findings and order, and remanded the matter to the compensation judge for reconsideration.^[3]  Because of our focus on specific areas of concern, it is understandable that the compensation judge believed that certain other issues and factual findings not specifically listed by our decision were final, and that she was precluded - - by the res judicata effect of her earlier findings - - from determining whether the employee’s injuries predating December 2003 were temporary or permanent.  However, because all issues remained open on remand, none of the compensation judge’s original 2004 findings and order had a res judicata effect.  At the time of the 2007 hearing, therefore, the compensation judge was not precluded from determining whether the employee’s pre-December 2003 injuries were temporary or permanent.

For that reason, we vacate those portions of the compensation judge’s findings and order that are related specifically to the issue of whether the employee’s pre-December 2003 injuries were temporary or permanent, and ask that the judge again address that issue.  We vacate Findings Nos. 8, 9 and 24, and Order Nos. 4, 5, and 6 of the Findings and Order issued October 12, 2007.  We vacate the following findings and orders included in the Amended Findings and Order issued on October 24, 2007:

The employer and Western National also appealed but did not address in their brief other findings and orders, including the findings that the employee sustained a minute trauma injury to his cervical spine which culminated in disability on May 4, 2004, that he sustained a minute trauma injury to his lumber spine which culminated in disability on April 10, 2007, and that the employee is entitled to payment of benefits related to those injuries.  Those findings and related orders are affirmed, and will not be considered on appeal.^[4]  The issues to be considered on remand is whether the employee’s pre-December 2003 injuries were temporary or permanent and therefore whether any apportionment of liability for the employee’s low back condition should be made as between those injuries and the employee’s April 10, 2007, injury.

The compensation judge shall issue her decision based on the existing record, but may, at her discretion, allow additional witness testimony or additional arguments by the parties.