To Modify or Not to Modify: The Latest Update on Distal Clavicle Excision Ratings

Impairment ratings related to a common surgical shoulder procedure in workers’ compensation claims, the distal clavicle excision, have come under increased scrutiny in recent years. Controversy has been related to two issues: when a rating is warranted and how the rating is properly calculated. The Iowa Court of Appeals recently ruled on the proper calculation of distal clavicle excision impairments in Koeller v. Cardinal Logistics Mgmt. Corp. and ACE American Ins. Co., No. 25-0172, 2025 WL 3471237 (Iowa Ct. App., Dec. 3, 2025). In a workplace injury, Koeller tore his supraspinatus tendon.  After conservative treatment failed, Koeller underwent surgery with Dr. Matthew Bollier: a left shoulder arthroscopy with SLAP repair, biceps tenotomy, debridement, subacromial decompression, and distal clavicle excision. Dr. Bollier assigned an impairment rating of 6% to the upper extremity, based on loss of range of motion. He did not assign any impairment related to the distal clavicle excision, finding that part of the surgery was not caused by Koeller’s work injury.

Koeller later underwent an independent medical evaluation with Dr. Mark C. Taylor, who assigned a 19% impairment rating to the left upper extremity based on loss of range of motion (9%), distal clavicle excision (10%) and slight weakness of supination (1%). Dr. Taylor found Koeller’s distal clavicle excision to be a result of his work injury because, “but for the work injury, Mr. Koeller would not have required a distal clavicle excision at the time that he did.”  Id. at 2.  Dr. Taylor did not apply the 25% modifier from Table 16-18 of the AMA Guides to the 10% distal clavicle rating from Table 16-27. Dr. Taylor opined that Table 16-27 is a stand-alone table for which no modifier is appropriately used, and that it was inadvertently listed in the Guides as one of the tables to which the modifier should be applied.

Dr. Brian Crites provided a third medical opinion wherein he agreed with Dr. Taylor’s 10% rating for the distal clavicle excision with no modifier application.

At the arbitration hearing, the deputy commissioner accepted Dr. Taylor’s 9% rating for loss of range of motion and agreed that a rating for the distal clavicle resection was appropriate because it was a “documented part” of the surgery. Id. At 6. However, the deputy rejected the 10% impairment ascribed to the distal clavicle excision (without the modifier) along with Dr. Taylor’s arguments against applying the 25% modifier. The deputy cited the appeal decision, Jay v. Archer Skid Loader Service, LLC, 2022 WL 17078713 (Iowa Workers’ Comp. Comm’r), in which the Commissioner ruled that the AMA Guides require the application of the 25% multiplier from Table 16-18 to distal clavicle excision ratings. Therefore, the deputy applied the multiplier, making the rating for the distal clavicle excision 3%, rather than the 10% Dr. Taylor assigned. Both parties appealed the decision and the Commissioner affirmed. Both parties then filed for judicial review. 

At the district court level, Koeller argued that in accepting Dr. Taylor’s rating, but making adjustments to it, the agency violated Iowa Code section 85.34(2)(x), which prohibits the agency from using lay testimony or agency expertise when determining permanent impairment. The district court disagreed, finding the agency had not relied on agency expertise, but had instead rejected Dr. Taylor’s distal clavicle excision rating, because he failed to follow the AMA Guides, which specifically direct that a 25% modifier be applied to resections in the upper extremities. The court found that not making the small correction “would contradict precedent and the plain meaning of the statute.” Id. Therefore, the district court affirmed the Commissioner’s decision.

On appeal, the Iowa Court of Appeals agreed the agency’s decision did not violate Iowa Code section 85.34. It also addressed Cardinal’s argument that Dr. Bollier’s rating should have been accepted rather than Dr. Taylor’s, due to its superior credibility. Ultimately, the Court of Appeals found the deputy commissioner’s reasoning was supported by substantial evidence. Based on these two factors, the district court’s decision was upheld.

The lengthy partial dissent in the ruling was also informative, discussing in depth the technical provisions of the AMA Guides and the rationale behind the argument against applying the 25% modifier to distal clavicle excision ratings. 

In addition to the technical issue of how to calculate distal clavicle excision ratings, this case also suggests broader questions such as whether the Commissioner or medical experts are the authority on the correct interpretation of the AMA Guides, what deference should be given on appeal, and whether the result may eliminate the distal clavicle modifier altogether, if a deeper causation analysis were applied as raised by Dr. Bollier in his report. Given the increasing frequency of distal clavicle excision procedures, we expect this is not the last we will hear on this issue. Application for further review of Koeller is pending. Stay tuned for more updates.