###### Abstract  
In cementless Total Hip Arthroplasty (THA), achieving high primary implant fixation is crucial for the long-term survivorship of the femoral stem. While orthopedic surgeons traditionally assess fixation based on their subjective judgement, novel vibration-analysis fixation-monitoring techniques show promising potential in providing the surgeon with objective and quantifiable fixation measurements. This study presents a dynamic response measurement protocol for implant endpoint insertion and evaluates this protocol in the presence of artificial soft tissue. After the artificial femur was prepared in accordance with the THA protocol, the implant was inserted and progressively hammered into the cavity. The Pearson Correlation Coefficient (PCC) and Frequency Response Assurance Criterion (FRAC) corresponding to each insertion hammer hit were derived from the Frequency Response Functions (FRF) corresponding to each insertion step. The protocol was repeated with the artificial femur submerged in artificial soft tissue to imitate the influence of anatomical soft tissue. The FRAC appeared overall more sensitive than the PCC. In the presence of the artificial soft tissue the technique yielded higher PCC and FRAC values earlier in the insertion process. The measurements with artificial soft tissue produced FRFs with fewer peaks, lower resonance frequencies, and overall higher damping factors. The soft tissue appears to limit the fixation-change detection capabilities of the system and a promising potential remedy to this limitation is suggested. T +
Footnote †: journal: _Sci._  
_Applied_  
_sciences_  
_Article_  
_Influence of Artificial Soft Tissue on Intra-Operative Vibration Analysis Method for Primary Fixation Monitoring in Cementless Total Hip Arthroplasty_  
_Academic Editor_  
_[PERSON]_  
Received: 15 March 2022  
Accepted: 14 April 2022  
Published: 15 April 2022  
**Published: 15 April 2022**  
orthopedic professionals. Consequently, during cementless THA, orthopedic surgeons strive to consistently achieve optimal primary implant stability. A multitude of studies have addressed the challenge of objectively assessing orthopedic implant fixation intraoperatively. A notable portion of these studies focus on assessing the fixation of acetabular and femoral implants intraoperatively, using methods based on vibration analysis (VA) [3; 4]. Techniques based on VA have produced promising results when it comes to intraoperative stability monitoring. These techniques aim to provide quantitative feedback that can be utilized by the surgeons intraoperatively to produce consistent and repeatable optimal implant stability. Other works employ vibro-acoustic methods to assess femoral stem fixation [5; 6]. As an additional function, these VA and vibro-acoustic techniques have displayed potential for micro-crack detection, prior to crack propagation and eventual bone fracture [4; 6]. Such a functionality would alert the surgeon in case of micro-crack formation to stop further hammering of the stem and avoid an imminent fracture. A different study employing vibro-acoustic methods by [PERSON] et al. shifts the focus on investigating the compaction broaching process instead of the implant insertion process, as a prerequisite for optimal primary stability [7]. An alternate approach includes assessing primary fixation by means of instrumented hammering [8; 9]. [PERSON] et al. [10] addressed the influence of bovine soft tissue on acetabular cup VA primary fixation assessment. In this study, the resonant frequencies were observed to reduce with increasing thickness of bovine soft tissue layers. The underlying principle of using VA to monitor the stability of an implant can be explained in the case of a femoral stem insertion. As the stem is progressively hammered into the femoral cavity, the resonant frequencies observed in the Frequency Response Function (FRF) of the combined femur-implant structure rise due to an increase in stiffness of the combined structure.