Table 5 Detailed list of categorised definitions for bone/fracture and implant/surgery complications located at the proximal humerus

(Secondary) Loss of reduction

= secondary fragment displacement

= redisplacement

Significant change of head position against shaft or fragment dislocation compared to the immediate postoperative position

= secondary dislocation of greater tuberosity

Relative change of greater tuberosity compared to the immediate postoperative position

Malunion

Fracture healed with deformity and bone unites in abnormal position and/or alignment (e.g. varus/valgus, rotational malunion)

1. as a consequence of loss of reduction

2. as a consequence of inadequate/insufficient anatomical reduction as observed on postoperative X-rays.

Delayed healing

Insufficient signs of bridging/continuous fracture line still visible up to 6 months

Nonunion

Indiscernible signs of bridging/continuous fracture line still visible after 6 months

Head impaction

= secondary fracture impaction

Secondary impaction/sintering of the head fragment with consecutive intraarticular screw penetration due to mechanical failure (not due to avascular collapse of the head fragment) compared to immediate postoperative position

Head necrosis

In situ death of bone within the humeral head due to disruption of blood supply, leading to partial or complete collapse of the head

Refracture

= secondary fracture at the same site

After fracture is healed: refracture occurs at the same humeral site with a load level otherwise tolerated by normal bone after the bone has solidly bridged

Functional deficit

As assessed with the functional scores of DASH, SPADI, ROM and Constant-Murley

Implant/surgery

Primary malpositioning of plate

Failure to fix each fragment and/or failure to implant plate according to technical guide [18] (including anatomical reduction and plate positioning i.e. at least 8 mm distal to the upper end of the greater tubercle) during operation

Primary malpositioning of screw

Screw perforation into glenohumeral joint during operation

Secondary screw loosening: back-out

Relative change outwards of screw position in relation to postoperative position

Secondary screw loosening: perforation

Perforation of one screw through the cortex of the head (no initial perforation)

Implant loosening

= Proximal screw and plate pull out

= Distal screw and plate pull out

Multiple proximal or distal screw loosening leading to firstly, relative movement between one main fragment and the plate and secondly, pull-out of the implant

Implant failure/breakage

Plate/screw breakage