JAAOS - 2026-06-22 - Journal Article
Z-type Clavicle Fractures in Adults: A Retrospective Comparative Study of Outcomes.
Muhammad M, Borgida JS, Wagner RK, Griffin JT, Sierra-Arce CR, Musick AN, Gregg AT, Policicchio TJ, van Duuren D, Lehle CH, Ly TV, Aneja A
Topics
Key Takeaway
Nonoperatively managed Z-type clavicle fractures had a 17% rate of surgery to promote healing—identical to non-Z-type fractures—but surgical fixation reduced that rate to 1.1%, while excluding implant removal revealed a significantly higher unplanned reoperation burden in the nonsurgical group (20% vs. 4.2%, P=0.009).
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Summary
This study asked whether Z-type midshaft clavicle fractures—defined by complete displacement with a vertically oriented butterfly fragment ≥1 cm—carry higher failure rates with nonoperative management than standard displaced midshaft fractures, and whether operative fixation reduces unplanned reoperations. Among nonoperatively managed fractures, Z-type and non-Z-type patterns had statistically equivalent rates of surgery to promote healing (17% vs. 22%, P=0.552; OR 0.84). Surgical management of Z-type fractures reduced surgery-to-promote-healing to 1.1% vs. 17% nonoperative (P=0.002), and when implant removal was excluded, nonoperative Z-type fractures had a significantly higher unplanned reoperation rate (20% vs. 4.2%, P=0.009).
Key Limitation
Retrospective design with no standardized protocol for operative vs. nonoperative selection introduces significant treatment-allocation bias, as surgeons likely preferentially operated on higher-energy or more symptomatic Z-type fractures.
Original Abstract
INTRODUCTION
Midshaft clavicle fractures with a "Z" deformity have historically been considered a surgical indication, although evidence is limited. This study compared rates of surgery to promote fracture healing between Z-type and non-Z-type clavicle fractures managed nonoperatively (nonsurgical cohort) and all-cause unplanned (re)operation rates among operatively and nonoperatively managed Z-type fractures (Z-type cohort).
METHODS
This retrospective cohort study included adult patients with midshaft clavicle fractures treated at two level 1 trauma centers between 2010 and 2023. Z-type fractures were defined as comminuted fractures with complete displacement and a vertically oriented butterfly fragment of ≥1 cm. The primary outcome was the rate of surgery to promote fracture healing in the nonsurgical cohort and the all-cause unplanned surgery rate in the Z-type cohort.
RESULTS
In total, 35 nonsurgical Z-type fractures, 157 nonsurgical non-Z-type fractures, and 95 surgical Z-type fractures were included. Rates of surgery to promote healing were similar between nonoperatively managed Z-type and non-Z-type fractures (17% vs. 22%, P = 0.552). Multivariable analysis showed no association between Z-type fractures and surgery to promote fracture healing (odds ratio, 0.84; 95% confidence interval, 0.29 to 2.17; P = 0.737). Among Z-type fractures, all-cause unplanned surgery rates were comparable between nonsurgical and surgical management (20% vs. 28%, P = 0.333). However, when excluding implant removal, nonoperatively managed Z-type fractures had a significantly higher all-cause unplanned surgery rate (20% vs. 4.2%, P = 0.009). Surgical management of Z-type fractures had a lower rate of surgery to promote fracture healing compared with nonsurgical management (1.1% vs. 17%, P = 0.002).
CONCLUSIONS
Among fractures initially treated nonoperatively, Z-type and non-Z-type midshaft clavicle fractures had similar rates of surgery to promote fracture healing. Surgical management of Z-type fractures demonstrated a lower rate of surgery to promote fracture healing compared with nonsurgical management. Regardless of initial treatment, all-cause unplanned surgery rates were comparable for Z-type fractures.
LEVEL OF EVIDENCE
Therapeutic Level III.