Detaillierte Beitrags-Information
| Beitragstitel | “Coverage index and integrity of medial hinge”: two new radiological risk factors for secondary dislocation of humeral head fractures |
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| Beitragscode | P011 |
| Autoren | |
| Präsentationsform | Poster |
| Themengebiete |
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| Abstract |
Introduction Most of proximal humeral head fractures can be treated conservatively. However, further fragment dislocation may change initial decision-making. We describe two new simple radiological parameters representing risk factors for secondary fracture dislocation: “coverage index” and integrity of the medial hinge. Methods Radiological measurements were performed on AP and Neer’s view. “Coverage index” was defined as the ratio between the radius of the humeral head and the distance between the rotational center of the head and the axis of the shaft. The ratio was estimated on AP and Neer views. “Medial hinge” was considered intact, if the medial cortices were in line on AP-view. “Cranial migration of the shaft into the head was termed “telescoping” and medial migration of the metaphysis relative to the humeral head was termed ”medialization”. For demographics descriptive ANOVA Statistics were used. Further statistic evaluation was performed using t-test, Firth logistic regression and Tobit models. Results Radiographs of 198 patients (199 fractures) were evaluated. Average patient age was 69 years (range 26-99). According to Neer’s classification, there were 24 one-part fractures (12%) and 175 cases with more complex fractures (2, 3 and 4-part: 132;42;1). 66 fractures (33%) showed significant secondary dislocation of more than 5mm. Disruption of the medial hinge presented with an odds ratio for secondary dislocation 38.5 (p < 0.01). There was a strong inverse relationship the “fracture coverage” and dislocation rate on the AP (r= -0.733) as well on the Neer’s view(r= -0.481). In addition, two distinctively different patterns of fracture dislocation were observed: Medialization of the shaft with valgus displacement of the head in 22 out of 66 cases (33%) and telescoping of the diaphysis with Varus displacement of the head in 44 cases (66%). Conclusion: In our patients group, 33% of patients showed a secondary dislocation of > 5mm. A low “fracture coverage index” on either AP- or Neer´s view as well as a disrupted medial hinge are negative prognostic factors for secondary fracture dislocation. Two distinct dislocation pattern are seen, leading either to medial migration of the shaft with valgus displacement of the head or to cranial migration of the shaft and Varus displacement of the head. |