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Beitragstitel Influence of bone mineral density on mechanical properties of the cancellous bone within humeral head affected from glenohumeral osteoarthritis.
Beitragscode P118
Autoren
  1. Vilijam Zdravkovic Kantonsspital St. Gallen Vortragender
  2. Antonia Neels
  3. Jürgen Hofmann
  4. Bernhard Jost Kantonsspital St. Gallen
Präsentationsform Poster
Themengebiete
  • A08 - Grundlagenforschung
Abstract Introduction
Mechanical properties of cancellous bone within humeral head are increasingly interesting due to popularity of locking plates for proximal humeral fractures and stemless shoulder prosthetic design. Age or pathology related systematic osteoporosis influences the density of bone in humeral head. However, inactivity or pathology of the shoulder joint may also change the local bone quality and lead to reduced primary stability of bone/prosthesis interface. It was the aim of our study to find if bone mineral density correlates with load/displacement response of cancellous bone within the humeral head.
Methods

We assessed the bone mineral density using micro-CT (0.04 mm voxel size) and correlated the results with indentation load/displacement response. Resected parts of humeral heads (patients undergoing total shoulder replacement, n= 18) were used as probes. The region of interest was defined 0.5 mm to 6 mm medial from resection plane, presuming that it should be representative for the correspondent bone lateral from the resection plane (i.e. the region where anchors of stemless prostheses are placed). As the first step, micro-CT scans and assessment of the bone mineral density within the region of interest was performed. Afterwards, indentation tests were performed using a large probe (1 cm2) in a single destructive loading procedure. The load/displacement responses and bone mineral density values were correlated using linear and exponential models.
Results
The average bone mineral density was 120.4 mg HA/cm3 (range 13.3 to 362). Our results showed high correlation between the bone mineral density and the slope of load/displacement curve: r = 0.90 for linear model, and r = 0.91 for exponential model (p1x2 +p2x+p3).
Conclusions

Predominant factor determining bone quality and mechanical resistance to pressure appears to be the bone mineral density. In our model, the high coefficients of determination leave little unexplained variance that could potentially be attributed to trabecular structure. Further investigations about 3D trabecular orientation and anisotropy are necessary.