Fractured patients undergoing treatment with drugs that interfere with bone metabolism, with local or systemic severe diseases, with previous same limb segment fractures, or with previous nonunion fractures were excluded.
The pressure and pressure derivative behavior show that the multi-segment fracture model exists new flow regimes which are termed first interference formation linear flow and second interference formation linear flow and can be characterized by straight line with slope m1 and m2 on the pseudo bottom-hole pressure derivative curve.
The investigation included a metallographic analysis of the cracked cover segments and bent blades, Finite Element Method (FEM) stress and natural frequency analysis (of blades/cover segments), fracture mechanics and crack propagation analysis.
Within the first postoperative year, 6 cases of partial (grade II) and 9 cases of complete (grade III) humeral head necrosis were found (8 times after 3-segment fracture, 5 times after 4-segment fracture, and twice after 2-segment fracture), but no joint replacement was necessary in any patient.
These included two 2-segment fractures, seven 3-segment fractures, and two 4-segment fractures.
There were 34 2-segment fractures, 42 3-segment fractures, and 11 4-segment fractures, including 7 dislocation fractures.
In the Neer classification, there were 34 2-segment fractures, 42 3-segment fractures, and 11 4-segment fractures and 7 dislocation fractures (four 4-segment fractures and three 3-segment fractures; median age of patients: 39 (33 75) years).
The restoration of the anatomy was better for 2-segment fractures than for complex fractures (p = 0.01).
There is no consensus about the management of displaced 3- and 4-segment fractures (Zyto 1998, Doursounian et al. 2000, Hintermann et al. 2000, Resch et al. 2001, Hente et al. 2004, Meier et al. 2006).
