title: Acoustic pattern evaluation during cementless hip arthroplasty surgery may be a new method for predicting complications.
abstract: BACKGROUND
  Although surgeons must perform implantation of the cementless stem during total hip arthroplasty (THA) without complications, assessment is left to the surgeon's intuitive judgement, which could contain inter/intra-observer bias variety. We therefore asked (1) whether the sound created during the stem implantation could be evaluated objectively and (2) whether those sounds are correlate to the complication specific to the cementless stems. Our hypothesis is that the sounds produced during stem insertion could be quantified and related to the complications.
  
  
  METHODS
  In 71 THAs, we quantified the sound produced during stem insertion and investigated the relationship between these sounds and the occurrence of intraoperative fracture and subsidence.
  
  
  RESULTS
  The sound data were divided into two patterns: Patterns A and B. The difference between the peak value (dB) at the most common frequency (near 7 kHz) and the second most common frequency (near 4 kHz) of strikes during the final phase of implantation in Patterns A and B showed a significant difference. Adverse events on intraoperative fracture and subsidence were significantly less common in patients with Pattern A than in those with Pattern B (six of 42 hips with Pattern A and 13 of 29 hips with Pattern B, p = 0.004). Pattern A in predicting a clinical course without those adverse events was 69.2% and the specificity was 68.4%. Positive and negative predictive values were 85.7% and 44.8%, respectively.
  
  
  CONCLUSIONS
  The sound generated during stem insertion was quantified. Those sound patterns were associated with complications.
authors.affiliation: Department of Orthopaedic Surgery, Juntendo University Shizuoka Hospital, 1129 Nagaoka, Izunokuni, Shizuoka 410-2295, Japan.
authors.forename: Itaru
authors.initials: I
authors.lastname: Morohashi
authors.affiliation: Department of Bio-Engineering, Juntendo University Institute of Casualty Center, 1129 Nagaoka, Izunokuni, Shizuoka 410-2295, Japan.
authors.forename: Hideaki
authors.initials: H
authors.lastname: Iwase
authors.affiliation: Department of Orthopaedic Surgery, Juntendo University Shizuoka Hospital, 1129 Nagaoka, Izunokuni, Shizuoka 410-2295, Japan.
authors.forename: Akio
authors.initials: A
authors.lastname: Kanda
authors.affiliation: Department of Host Defense and Biochemical Research, Tokyo Denki University, 5 Senju Asahi-cho, Adachi-ku, Tokyo 120-8551, Japan.
authors.forename: Taichi
authors.initials: T
authors.lastname: Sato
authors.affiliation: Department of Orthopaedics, Juntendo University, 2-1-1 Hongo, Bunkyo-ku, Tokyo 113-8421, Japan.
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Homma
authors.affiliation: Department of Orthopaedic Surgery, Juntendo University Shizuoka Hospital, 1129 Nagaoka, Izunokuni, Shizuoka 410-2295, Japan.
authors.forename: Atsuhiko
authors.initials: A
authors.lastname: Mogami
authors.affiliation: Department of Orthopaedic Surgery, Juntendo University Shizuoka Hospital, 1129 Nagaoka, Izunokuni, Shizuoka 410-2295, Japan.
authors.forename: Osamu
authors.initials: O
authors.lastname: Obayashi
authors.affiliation: Department of Orthopaedics, Juntendo University, 2-1-1 Hongo, Bunkyo-ku, Tokyo 113-8421, Japan.
authors.forename: Kazuo
authors.initials: K
authors.lastname: Kaneko