A jammed truck door, a torn rotator cuff, and a single medical table have changed how Iowa workers' comp claims add up.
On May 15, the Iowa Supreme Court ruled for Kevin Koeller, a semitruck driver for Cardinal Logistics Management Corporation, in a fight over how much permanent impairment he suffered after a 2022 shoulder injury. The decision reverses how Iowa's workers' compensation commissioner has been reading the AMA Guides to the Evaluation of Permanent Impairment – the medical reference book that, since 2017, has carried the force of law in Iowa workers' comp cases.
For Ace American Insurance Company, Cardinal's carrier and a named appellee, the ruling means higher impairment ratings on shoulder claims involving a distal clavicle excision.
The injury happened on October 5, 2022. Koeller went to unload his truck and grabbed the roll-up door with his left hand. A pallet had fallen inside and jammed it shut. When he yanked, his shoulder popped. The door eventually had to be opened with a floor jack.
MRIs showed partial tendon tearing and some preexisting AC joint wear. After injections and physical therapy failed, orthopedic surgeon Matthew Bollier diagnosed a traumatic left rotator cuff tear and operated in February 2023. The surgery included a distal clavicle excision – removing part of the collarbone.
Then three doctors gave three different impairment ratings.
Bollier, the treating surgeon, came in at 6%. He refused to include the clavicle excision, saying it was not caused by the work injury.
Mark Taylor, who handled the independent medical exam for Koeller, rated him at 19%. He tied the clavicle work to the injury, reasoning that Koeller would not have needed the excision when he did had the work injury not happened, and that Koeller had no left shoulder or AC joint pain before October 2022.
A third doctor, Brian Crites, backed Taylor on causation.
The deputy commissioner believed Taylor on the medicine but disagreed on the math. Taylor pulled a 10% impairment figure straight from Table 16-27 of the AMA Guides, which covers distal clavicle excisions. The deputy said that 10% had to be multiplied by 25%, the relative value of the AC joint given in Table 16-18. The math dropped the excision contribution from 10% to 3%. Total impairment fell from 19% to 13%.
The commissioner upheld the deputy. The district court agreed. So did a split Iowa Court of Appeals.
The Supreme Court reversed. Justice Mansfield, writing for a unanimous bench, walked through the AMA Guides and found a genuine contradiction. The opening paragraph of section 16.7 says all the relevant tables – including Table 16-27 – get multiplied by Table 16-18. But the specifics tell a different story. Other joint tables carry footnotes telling readers to multiply by Table 16-18. Table 16-27 does not. Other tables give a joint impairment figure that needs conversion. Table 16-27 already provides a percentage of upper extremity impairment. And the Guides' own worked examples apply the multiplier everywhere except to Table 16-27.
Applying Iowa Code section 4.7, which says the specific beats the general when two provisions clash, the court came down for the specifics. The commissioner, Mansfield concluded, was wrong to apply the Table 16-18 multiplier to a distal clavicle excision under Table 16-27.
The court also drew a clearer line around what the commissioner can and cannot do. Iowa Code section 85.34(2)(x) makes the AMA Guides the law for scheduled-member ratings. The commissioner can pick between expert opinions, but cannot rewrite how the Guides themselves work. The Guides carry the force of law, Mansfield wrote, and what the law requires is for the agency and the courts to settle.
The case goes back to the commissioner for fresh proceedings.
For insurers, the practical message is short. Iowa carriers and TPAs handling shoulder claims with a distal clavicle excision should not apply the Table 16-18 multiplier to Table 16-27 values. That single change can push a single claim's rating from the low teens into the high teens. Across a book of business, that is real reserve exposure.
