The employee appeals the compensation judge’s findings that he is not entitled to additional permanent partial disability benefits and that the employee’s work-related injuries are not substantial contributing factors to his need for medical treatment from February 27, 2009, through May 3, 2011.  We affirm.

On March 6, 2002, and March 17, 2005, Michael G. Ricke, the employee, sustained admitted work-related carpal tunnel injuries to his right wrist while working as a butcher for Plantenberg Market, the employer.  The employer was insured for workers’ compensation liability by RAM Mutual Insurance Company.  The employee underwent carpal tunnel release surgery on his right wrist in May 2002, in March 2003, and in March 2005.  After the first two surgeries, the employee was able to return to work at his regular job.  He was assigned a .5 percent permanent partial disability rating after the second surgery.  The third surgery included a hypothenar fat pad surgery, which was performed by Dr. Christopher Widstrom.  After this surgery, the employee indicated that his hand did not feel right.  He returned to work at a light duty position and reported experiencing shoulder pain.  In September 2005, the employee underwent a functional capacities evaluation.  Based on that evaluation, Dr. Widstrom assigned the employee permanent restrictions including no lifting over 45 pounds and no repetitive grasping or manipulation with the right hand.  The employee stopped working for the employer when the company could not accommodate his restrictions.

In January 2006, the employee was evaluated by Dr. Scott McPherson at Tria Orthopedics.  Dr. McPherson diagnosed right median neuropathy with neuritis-type symptoms and indicated that the employee’s symptoms were reasonably tolerated.  He recommended that they observe the employee, that he avoid further surgery, and that he not return to his previous job.  The employee also saw Dr. T. L. Satterberg at Midsota Plastic Surgeons in March 2007.  Dr. Satterberg ordered an EMG, which did not show any changes from a prior EMG.  Dr. Satterberg recommended that they follow the employee and re-evaluate if his symptoms changed.

In 2007, the parties litigated issues regarding the employee’s weekly wage calculation.  A hearing before a compensation judge was held in June 2007 on the issues of 1) whether the employee was entitled to include wages from another employer and from a volunteer emergency services position in his weekly wage calculation, and 2) whether the employee was entitled to temporary partial disability benefits from and after September 1, 2006.  The compensation judge included earnings from both positions and calculated the other employment wage using the statutory method under Minn. Stat. § 176.011, subds. 3 and 18, and awarded temporary partial disability benefits.  The employer and insurer appealed the wage issues, and this court affirmed the inclusion and the calculation of the other employment wage, but reversed the inclusion of the volunteer position wage.^[1]  No other issues were addressed.

In February 2007, the employee began working at Schmitz Pallet Service, which was renamed KB Pallet, as a truck driver.  Later, the employee worked on a pallet machine in a position within his restrictions.  The employee sought treatment for his right wrist with Dr. Mark Halstrom at Williams Integracare Clinic in February 2009.  Dr. Halstrom diagnosed carpal tunnel syndrome and suggested an MRI.  He indicated that the employee had not sustained a new injury, but that he had experienced a progression of symptoms.  The employee reported wrist pain and paresthesia as well as some neck symptoms.  The employee underwent physical therapy and returned to work for KB Pallet in different positions.  While working, the employee wore a wrist brace.

In an April 16, 2010, report, Dr. Halstrom indicated that the November 2009 MRI showed degenerative changes in a ligament and diagnosed progressive laxity and weakness related to the disruption of the wrist ligaments.  He opined that the employee’s work for the employer was a substantial contributing factor to his condition and assigned 11 percent permanent partial disability under Minn. R. 5223.0470, subp. 3.B.(3).  Dr. Halstrom recommended right hand restrictions as well as prolotherapy treatment, and if that failed, possible surgery.  In September 2010, Dr. Halstrom again recommended prolotherapy and additional physical therapy.  According to Dr. Halstrom’s records, the insurer would not approve this treatment.

On March 9, 2011, the employee was examined by Dr. William Call at the employer and insurer’s request.  Dr. Call opined that the employee’s carpal tunnel syndrome was the only condition he sustained while working for the employer.  He indicated that the only issue with the employee’s right wrist was mild degenerative changes and that there was no evidence of wrist instability.  He concluded that the medical treatment after January 3, 2006, was not reasonable and necessary for the employee’s work injuries.  He also stated that there was no need for prolotherapy or physical therapy for the employee’s right wrist.  He would rate the employee at zero percent permanent partial disability and assign a work restriction of no lifting over 45 pounds on the right, but related that restriction to the employee’s degenerative changes.

On May 4, 2011, the employee injured his wrist while working at the pallet company when he pulled pieces of lumber from a stack of lumber above shoulder level.  The employee was treated by Dr. Halstrom, who recommended an MRI and a surgical consultation.  The employee began physical therapy in July 2011.  On August 11, 2011, the employee underwent an independent medical examination with Dr. David Fey.  Dr. Fey read the latest MRI as indicating that the employee’s wrist was essentially stable when compared to the 2009 MRI.  Dr. Fey concluded that the May 2011 incident was a temporary recurrence of symptoms that had resolved in one month and also that there was no evidence that the employee had sustained a new acute injury at that time.  The employee experienced increased pain and left the pallet company in February 2012 since there was no work available within his restrictions.  The employee testified that his wrist condition worsened while he was working at the pallet company.  The employee sought benefits from both the employer and the pallet company.  In March 2012, the employee settled his workers’ compensation claim against the pallet company on a full, final, and complete basis, including medical expenses.  The employee’s claim against the employer was not part of that settlement.  A partial award on stipulation was served and filed on March 29, 2012.

The employee continued to treat with Dr. Halstrom, who noted that the employee’s May 2011 injury was “the substantial contributing factor” for the employee’s symptoms at that time and that the previous injury was “a contributing factor.”  He concluded that the May injury “worsened things to the point that he really is not functional to the degree he was prior to May.”^[2]  Later, Dr. Halstrom opined that the May 2011 injury exacerbated the employee’s condition at that time, but that it was not a substantial contributing factor to all of his problems.  He concluded that most of the employee’s dysfunction was related to his work injuries for the employer, reasoning that repetitive use causes wear and tear, which loosens ligaments and wears out joints.

Dr. Call disagreed with Dr. Halstrom’s diagnosis of repetitive use injury and opined that there was no evidence that the employee had progressive laxity in his wrist or wrist instability and that he had no need for prolotherapy or surgery.  He also opined that any symptoms the employee was experiencing were the result of his injury when he was with the pallet company, not with the employer.  He emphasized that carpal tunnel release surgeries are not related to age-related degenerative changes or wrist instability, and that any lack of grip strength was not related to carpal tunnel syndrome.  In response, Dr. Halstrom repeated his conclusion that the employee’s “ongoing wrist dysfunction and carpal instability to me is a result of repetitive use and progressive damage of the ligaments that support the carpal bones.”^[3]

In January 2012, the employee underwent an independent medical evaluation with Dr. Robert Wengler.  Dr. Wengler diagnosed chronic median neuropathy of the right arm and opined that the employee sustained a Gillette^[4] injury while working for the employer, which was aggravated by the injury at the pallet company.  In a June 11, 2011, deposition, Dr. Wengler reiterated that the employee had a median nerve problem associated with his meat-cutting work.  He had no treatment recommendations for the employee and assigned 18 percent permanent partial disability under a Weber^[5] rating, asserting that the permanent partial disability schedules did not cover his loss of grip strength.  When asked about wrist instability, Dr. Wengler responded that he was not aware that the employee had an unstable wrist.  Dr. Call reviewed Dr. Wengler’s report and indicated that his opinions had not changed.  He disagreed with Dr. Wengler’s permanent partial disability rating, his testing technique for loss of grip strength, and his analysis of the employee’s condition.

In different pleadings, the employee claimed 18 percent permanent partial disability based on Dr. Wengler’s opinion, rehabilitation benefits, and payment of medical expenses.  The pleadings were consolidated and a hearing was held on two separate days:  June 19, 2012, and July 23, 2012.  The compensation judge found that the employee was entitled to rehabilitation benefits, that he was not entitled to additional permanent partial disability benefits, and that the employee’s work injuries in 2002 and 2005 were not substantial contributing factors to his need for medical treatment from February 27, 2009, through May 3, 2011.  The employee appeals.^[6]

The Workers’ Compensation Court of Appeals must determine whether the findings of fact and order are clearly erroneous and unsupported by substantial evidence in view of the entire record as submitted.^[7]  Substantial evidence supports the findings if, in the context of the entire record, they are supported by evidence that a reasonable mind might accept as adequate.^[8]  Fact findings are clearly erroneous if the reviewing court, looking at the entire evidence, is left with a definite and firm conviction that a mistake has been committed.^[9]  Findings of fact should not be disturbed, even though the reviewing court might disagree with them, “unless they are clearly erroneous in the sense that they are manifestly contrary to the weight of the evidence or not reasonably supported by the evidence as a whole.”^[10]

The employee asserts on appeal that the employer and insurer’s voluntary payment for medical treatment after 2006 and their failure to raise the issue of causation during previous litigation bar them from arguing that the employee’s medical treatment after 2006 was not causally related to his work injuries under the doctrine of res judicata.^[11]  The employee did not raise this issue at the 2012 hearing.  As a general rule, issues raised for the first time on appeal are not properly before this court and for that reason we do not consider the employee’s arguments regarding the doctrine of res judicata.^[12]

The employee also contends that substantial evidence does not support the compensation judge’s finding that employee’s need for ongoing medical treatment is not causally related to his work injuries for the employer.  The employee argues that the compensation judge’s finding that his ongoing condition is not related to his work injuries for the employer is inconsistent with the judge’s finding that the employee has permanent restrictions as a result those work injuries.

The employee bears the burden of proving, by a fair preponderance of the evidence, the compensability of his or her claim.^[13]  In this case, the compensation judge concluded the employee failed to prove the requisite medical causation.  “Medical causation is a distinct legal concept that concerns the connection between the primary injury and a later condition - - ‘how far the range of compensable consequences is carried, once the primary injury is causally connected with the employment.’”^[14]  While an injury need not be the sole cause of a subsequent disability or condition in order for liability to attach, the injury must be a substantial contributing factor.^[15]  Questions of medical causation fall within the province of the compensation judge.^[16]

The compensation judge found Dr. Call’s opinion more persuasive than those of Dr. Halstrom and Dr. Wengler.  A compensation judge’s choice between expert opinions is generally upheld unless the expert’s opinion is based on facts not supported by the evidence.^[17]  The employee claims that Dr. Call’s opinion is unsupported by facts in the record based on Dr. Call’s conclusion that the employee’s carpal tunnel syndrome had resolved.  Since the judge found that the employee had permanent restrictions as a result of his 2005 work injury, the employee argues that the judge’s reliance on Dr. Call’s opinion is incorrect and inconsistent.

Dr. Call opined that he saw no evidence of ongoing carpal tunnel syndrome and no evidence of ligament laxity or wrist instability, but did see evidence of mild age-related degenerative changes.  Based on his observations, Dr. Call was of the opinion that any work restrictions were related to those degenerative changes.  The compensation judge is free to accept all or part of an expert opinion.^[18]  The judge’s finding that the employee had permanent restrictions related to his carpal tunnel syndrome in 2005 does not compel the judge to find that the employee’s right wrist condition and need for treatment from February 27, 2009, through May 3, 2011, was also related to the employee’s 2005 work injury.  The compensation judge did not err by relying on part of Dr. Call’s opinion.

The compensation judge reviewed the medical records and the expert medical opinions regarding causation in this case.  In making decisions regarding causation, it is the compensation judge’s function to resolve conflicts in expert medical testimony.  Dr. Halstrom opined that most of the employee’s dysfunction was related to his work injuries with the employer, reasoning that the employee’s ongoing wrist dysfunction and carpal instability was a result of repetitive use and progressive damage of the ligaments that support the carpal bones.  He also recommended treatment with prolotherapy and additional physical therapy.  Dr. Call disagreed with Dr. Halstrom’s diagnosis of repetitive use injury and opined that there was no evidence that the employee had progressive laxity in his wrist or wrist instability.  He also opined that the employee had no need for prolotherapy or surgery and that any symptoms the employee was experiencing were the result of his injury when he was with the pallet company, not with the employer.  Considering all the testimony and the medical evidence, we find substantial evidence supports the compensation judge’s finding that the employee’s work-related injuries for the employer are not substantial contributing factors to the employee’s need for medical treatment for his wrist from February 27, 2009, through May 3, 2011.^[19]  Accordingly, we affirm.

The employee also argues that the compensation judge’s finding that the employee was not entitled to additional permanent partial disability is not supported by substantial evidence.  Dr. Wengler assigned the employee an 18 percent permanent partial disability rating as a Weber rating.  Dr. Halstrom assigned 11 percent permanent partial disability for carpal instability under Minn. R. 5223.0470, subp. 3.B.(3).  Dr. Call opined that he would assign a zero percent rating under Minn. 5223.0470, subp. 2.B.(1) for nerve entrapment that resolved with treatment, but stated in his deposition that the .5 percent permanent partial disability paid after the second carpal tunnel surgery was appropriate.  Given Dr. Call’s opinion that there was no evidence that employee had wrist instability, substantial evidence supports the compensation judge’s finding that the employee was not entitled to additional permanent partial disability.  We affirm.