Recently, the Tennessee Workers’ Compensation Panel addressed when an intervening incident may break the chain of causation for an underlying injury and eliminate further exposure.  United Parcel Service, Inc. v. Sabrina Brown, Tenn. Special WC App. Panel, No. M2014-01332-SC-R3-WC (Tenn. WC App. Panel, 2015).  In this case, the claimant injured her right knee on July 8, 2010.  She received initial medical care and temporary benefits.  Initial diagnostic testing suggested the claimant had a torn anterior cruciate ligament.  Surgery took place on September 9, 2010.  Immediately following surgery the treating physician found the claimant had normal post-surgical findings and instructed the employee to use crutches, place no weight on her right leg and wear a brace.

In or around October of 2010 (approximately one month following surgery) the claimant was in her backyard.  She noticed a sharp object laying on the ground and placed both crutches to her left side and attempted to reach down to pick up the object.  In doing this she lost her balance and felt an immediate twinge in the knee.

Subsequent to this event the treating physician had concerns the claimant had a possible failure of the ACL repair.  By December of that year the treating physician concluded the graft or surgery had failed and recommended an additional surgery.  The employer argued there had been a break in causation and the employer should not be held responsible for additional care.

The Appeals Panel determined there was not a break in the chain of causation and relied heavily upon Anderson v. Westfield Grp., 259 S.W.3d 690 (Tenn. 2008).  Generally, the Court held the aggravation of an original injury is compensable if it is direct and natural result of the compensable injury.  In addition, the Panel relied upon the treatise created by Larson who determined every natural consequence that flows from the injury likewise arises out of the employment injury.  The Appeals Panel referenced this as the “natural consequences rule.”  The Panel, however, recognized this rule has a limit.  The limit hinges on whether the subsequent injury is the result of independent intervening causes such as the employee’s own conduct.  In essence, every natural consequence that flows from the initial injury is compensable or related, “unless it is result of an independent intervening cause attributable to the claimant’s own intentional conduct.”  In addition, the chain of causation can be broken if it is found that, “the injured employee, knowing of his weakness, rationally undertakes to do things likely to result in harm to himself, the chain of causation is broken by his own negligence.”

In this matter the authorized treating physician testified he did not believe the claimant had done anything wrong in attempting to lift the item out of her backyard.  With respect to this he testified, “it was my opinion that Ms. Brown’s activities during her initial post-operative period were not inappropriate.  So I didn’t think that she was at fault for doing anything wrong that was out of the ordinary for post-operative ACL reconstruction.”

The Court found there was no negligence nor any intentional act.  As a result, the Court found the chain of causation was not broken.

In essence, unless the subsequent injury or event is work-related for a separate employer and one can invoke the “last injurious rule” the intervening incident or activity must be fairly significant.  It must rise to the level of intentional conduct or negligence.  This is a much tougher threshold.