Background

Proximal humeral fractures (PHF) are common fractures and account for 4–6% of all fractures [1,2,3]. They are associated with osteoporosis and 78% of the fractures are seen in patients above the age of 65 [4]. Since 1970 it has been widely believed that 85% of all PHF were minimally displaced and could be managed non-surgically while the remaining 15% were displaced and should be managed surgically [5]. However, more recent epidemiological studies have consistently reported much higher prevalences of displaced fractures ranging from 51 to 86% [3, 6,7,8]. The most commonly performed surgical procedures include internal fixation with locking plates or humeral nails or replacement of the humeral head with a hemiarthroplasty or a total reverse prosthesis. However, recent randomized clinical trials [9,10,11,12] and meta-analyses of randomized trials [13,14,15,16,17,18] or non-randomized trials [19, 20] have questioned the benefits of these procedures, even for displaced fractures. A call for more non-surgical treatments of PHF has emerged in the scientific literature [21,22,23,24].

Any evidence-based recommendation of a treatment modality, surgical or non-surgical, presupposes knowledge on benefits and harms. Guidelines for reporting of clinical effects with validated clinical outcome instruments are available and widely used. However, when it comes to reporting of complications and adverse events after management of PHF there is a paucity of standardized and validated terms and definitions. The majority of clinical studies on PHF deal with surgical management [25] and some complications like hardware failure and infection are obviously linked to surgery. However, complications following non-surgical management of PHF have not been systematically reviewed. Therefore, we aimed to systematically review the use of terms and definitions of complications after non-surgical management of PHF.

Methods

We conducted a systematic review of published peer-reviewed articles and book chapters according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines [26].

Search strategy

A search was conducted (June 2017) in PubMed, EMBASE, Cochrane Library and Scopus covering the years 2010–2017. The search strategy for journal articles is found in Additional file 1. For book chapters we searched WorldCat (2016–2017) using the search terms (humer* fra?tur* OR shoulder fra?tu*). We included references in English, German and French language.

Study selection and data-extraction

After exclusion of duplicates, two reviewers (A.S. and N.A.) screened the initial reference list by title and abstract. A third author (L.A.) reviewed any ambiguous abstracts to reach consensus on the article’s inclusion. Considering all included references we started full-text review and data extraction with the most recent references published in 2017 followed by consecutive series of 20 randomly selected references within previous years in reverse chronology. This process was terminated when all reviewers agreed that no additional relevant information was obtained. For all included references we documented bibliographical data and noted any general definition of ‘complication’ or ‘adverse event’ and any definition of individual complications or adverse events. We documented all individual complication terms reported and grouped them according to the relevant interventions. Terms related to non-surgical interventions were extracted for further analysis. The initial data-extraction was checked by a second reviewer and discrepancies were resolved by consensus. All data were managed and stored in a database using the data capture system REDCap [27] (Version 6.16.5,© 2018 Vanderbilt University).

Data synthesis

Extracted event terms were organized according to predefined event groups and specifications adapted from Audigé et al. [28]. Event term definitions were tabulated.

Results

The initial search yielded 1376 references (Flow chart, Fig. 1). Based on titles and abstracts we excluded 906 references that did not comply with the inclusion criteria. Thus, 470 references remained for full-text retrieval. Data extraction was terminated in consensus within the review group when 91 articles and 12 book chapters had been retrieved in full text and no new terms or definitions was identified in the last group of references.

Fig. 1
figure 1

Review flow diagram

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A total of 19 references (15 articles [13, 29,30,31,32,33,34,35,36,37,38,39,40,41,42] and 4 book chapters [24, 43,44,45]) reported terms and definitions of complications after non-operative management of PHF. The remaining references were excluded because they dealt with surgical management exclusively. From all the terms that were documented as being reported in the context of non-operative treatment, we identified the related papers, and then by checking back to these papers found out that only 19 papers were specifically focused on non-operative management.

After excluding spelling errors and clearly synonymous words 69 complication terms remained for further analysis (Table 1). They were grouped into 7 broad groups and 11 subgroups. Seven complication terms were defined.

Table 1 Adverse event terms
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Complication terms

All 69 complication terms were initially divided into local and non-local events. Local events were further grouped into ‘osteochondral’, ‘instability’, ‘shoulder pain’, ‘neurological’, ‘soft tissue (superficial)’, and ‘soft tissue (deep)’.

The largest group (39 terms) was the ‘osteochondral’ group covering the subgroups ‘arthritis’, ‘tuberosity migration/resorption’, ‘osteonecrosis’, ‘delayed union’, ‘malunion’ and ‘secondary fracture displacement’. All 39 event terms in this group were radiographically based.

The second largest group, ‘soft tissue (deep)’ (21 terms) covered ‘impingement’, ‘capsular’, ‘stiffness’ and ‘rotator cuff’. These event terms were defined clinically or by magnetic resonance imaging (MRI).

The remaining event terms were related to instability, pain, neurological injury, skin problems and the non-local events pneumonia and deep venous thrombosis.

Definitions

Among the full text searches we found 7 complication definitions. Six out of 7 definitions regarded radiographically defined events like malunion, nonunion, displacement and avascular necrosis (Table 2). Loss of power in arm was the only non-radiographically defined event term.

Table 2 Summary of definitions of adverse events
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Discussion

We found no consensus in the use of terms and definitions of complications after non-surgical management of PHF. Only very few definitions of complications and adverse events were identified. Relatively few references on non-surgical management were identified compared to surgical interventions. This confirms the findings of Slobogean et al. [25] who conducted a scoping review of the literature on PHF and reported that less than 5% of the body of literature dealt with non-surgical management compared to more than two thirds concerning surgical management. Despite this bias towards surgical literature we find it important to focus on complications after non-surgical management. A systematic reporting of complications and adverse events is needed for evidence-based suggestions and balanced decision-making [46].

‘Radiographical complications’

Most terms and definitions of adverse events are based on assessments of radiographs. Assessments based on radiographs may favor surgical management as osteosynthesis and arthroplasty aim to restore the anatomy of the proximal humerus or to replace the damaged joint. To designate a certain radiographic pattern as a complication or an adverse event does not necessarily mirror the functional outcome and expectations as reported by the patient. Displaced fractures in adults can be expected to heal with some degree of malunion when treated non-surgically. In that sense, a malunion is not necessarily an adverse event from the patient’s perspective. Even severe maluninon may be tolerated by patients with limited functional demands. More knowledge is needed to clarify the association between patient reported outcome and radiographically defined complications after non-surgical management.

Displacement, migration, malunion and nonunion are continuous variables brought into distinct categories often by poorly defined cut-off values. Three references proposed explicit definitions of ‘secondary varus displacement’ [13] ‘tuberosity displacement’ [39] and ‘varus malunion’ [41] based on measurements of degrees and millimeters on radiographs. The scientific and clinical validity of such definitions may be questioned and further studies may contribute to elucidate the clinical relevance of these commonly used complication terms.

The complication terms and definitions identified for non-surgical management can roughly be divided generically into three groups:

Pathoanatomical entities

‘Humeral head necrosis’ and ‘capsulitis’ are pathoanatomical diagnoses applied to radiological, clinical or intra-operative findings. Similarly, non-local terms like ‘pneumonia’ and ‘DVT’ are clinical and para-clinical (radiographs, ultrasound, blood tests) diagnoses rarely verified by pathologists.

Pathophysiological entities

‘Loss of perfusion’ leading to ‘humeral head ischemia’ and eventually ‘avascular necrosis of the humeral head’ are successive changes in a pathophysiological process. This process is quantified in the 3-stage definition of ‘avascular necrosis’ [13].

The process leading to ‘non-union’ or ‘pseudoarthrosis’ is captured in the 3-stage definition ‘delayed union’, non-union’, or ‘prolonged delayed union’ [41].

Biomechanical entities

The terms related to rotator cuff problems are based on a biomechanical understanding of successive changes caused by muscular imbalance. The term ‘rotator cuff’ is usually followed by specifications like ‘tear’ and ‘injury’ (based on imaging), ‘pain’ (based on history), or ‘dysfunction’ and ‘deficiency’ (based on a functional understanding).

The terms related to ‘impingement’ are based on a biomechanical understanding of the process leading to pain and impairment. ‘Internal rotation impingement’ is clinically defined while ‘impingement of the greater tuberosity on the acromion’ illustrates a biomechanical understanding.

Future aspects

To obtain consensus on terms and definitions we plan to apply a Delphi consensus process based on the findings from the systematic review. An international group of shoulder surgeons will independently assess and comment on the proposed terms and definitions through a series of online surveys. A core event set will be developed and further validated. A similar approach has previously been applied to complications associated with arthroscopic rotator cuff tear repair [28].

Conclusions

Based on this systematic review we found no consensus on terms and definitions of complications and adverse events after non-surgical management of PHF. Most terms and definitions are based on radiographical assessments and the clinical relevance of terms and definitions from the patients’ perspective remains to be demonstrated. We recommend steps towards the development of a core event set of complication terms based on consensus among shoulder and trauma specialists and with involvement of patient representatives in the validation process.