Quantifying bone compaction and implant-bone contact in uncemented total hip arthroplasty through μCT and digital volume correlation: A cadaveric study.

Background: The stability of uncemented implants during total hip arthroplasty (THA) depends on bone compaction and the bone-implant contact area achieved during the surgical process, particularly during broaching and implantation. However, the evaluation of these factors in actual hip is limited through experimental studies. Therefore, the aim of this study was to quantify bone compaction, and the bone-implant contact area achieved during uncemented THA through a μCT-based cadaveric study of three femur samples.

Methods: Three cadaveric femur samples underwent uncemented THA, with μCT scans conducted at intermediate surgical steps. The bone compaction resulting from the surgical process was quantified using two parameters: (a) displacement and strain induced using Digital Volume Correlation (DVC), (b) changes in bone volume fraction (BV/TV) around the bone-implant interface. Furthermore, the bone-implant contact, and its location were evaluated, including an assessment of the robustness and sensitivity of the measurements.

Results: The DVC showed that the trabecular bone deformed plastically, with a displacement of 0.09 ± 0.13 mm, a Von-Mises strain of 7082.28 ± 9162.73 με due to the surgical process. Broken trabecular bone accumulated around the bone-implant interface, increasing BV/TV from 3.31 % to 20.69 %. Bone-implant contact (BIC) was limited, ranging from 3.05 % to 5.22 %, but 75.26 %-82.27 % of the maximum potential contact area (PBICA) was achieved. All samples established a three-point contact, and sensitivity analysis revealed a robust BIC calculation with minimal variability of ±0.87 %.

Conclusion: The findings offer important insights into bone-implant behaviour during the uncemented THA process. These insights could be useful for physics-based pre-surgical planning to evaluate the stability of uncemented implants and help surgeons choose the most appropriate implants for their patients.