Clavicle fractures do not increase the occurrence of later subacromial pain syndrome. A registry-based case-control study with 15-25 years of follow-up of 131.838 persons from the Danish National Patient Register

BACKGROUND: A clavicle fracture often changes the mechanical axes of the shoulder girdle due to displacement and shortening, potentially leading to scapular protraction and decreased subacromial space. If protraction of the scapula is a major risk factor for developing subacromial pain syndrome (SAPS), a previous clavicle fracture could increase the risk of later SAPS. The purpose of this study was to investigate if a previous clavicle fracture correlates with a higher occurrence or earlier diagnosis of SAPS.

METHODS: In this retrospective case-control study with data from the Danish National Patient Register, all persons aged 18-60 years, with any hospital contact due to a clavicle fracture (DS420) between January 1, 1996, and December 31, 2005, were identified as cases. For each case, five controls, matched on age and sex, were identified. Primary outcome was the first hospital contact with a SAPS diagnosis (DM751-755) registered more than 180 days following the fracture. Follow-up was until November 01, 2021.

RESULTS: 21.973 cases and 109.865 controls were included. The incidence of clavicle fractures was 76 fractures per 100.000 persons per year. Twenty-three percent were female. 1.640 (7.46%) cases and 8.072 (7.35%) controls received a SAPS diagnosis within the following 15-25 years, demonstrating no significant difference in the occurrence of SAPS (P = .56). The mean time from fracture to SAPS diagnosis was shorter for cases compared to controls (4040 vs. 4442 days, P < .001), and cases were slightly younger when receiving the diagnosis (51.3 vs. 53.6 years, P < .001). 1614 cases underwent surgical fixation. This subgroup had a statistically significant higher occurrence of later SAPS diagnosis (205 cases, 13%, P < .001).

CONCLUSIONS: Persons with a previous clavicle fracture did not have an increased occurrence of receiving a SAPS diagnosis compared to matched controls. However, the diagnosis was given 1-2 years earlier for people with a previous fracture. Based on these findings, no strong argument for protraction of the scapula as a major risk factor for the development of SAPS was found.