Table 3 Key findings from studies evaluating the role of acoustic analysis in detecting intraoperative fractures

Goossens et al. (2020)

Acoustic

3 (11.5%)

BPF quantifies the relative spectral power distribution of the measured sound signal. PCCs were calculated as a distance metric between the vibroacoustic response spectra of successive insertion hammer blows

A sharp decline in BPF and PCC, by up to approximately 75% during a consistent hammering sequence, suggests implant instability and is a warning for periprosthetic microfracture

Morohashi et al. (2017) [3]

Acoustic

2 (2.8%)

Pattern A = frequencies near 7 kHz became more accentuated as implantation progressed (n = 42)

Pattern B = no accentuation of frequencies near 7 kHz (n = 29)

Intraoperative fracture and postoperative subsidence were less common in patients with Pattern A (n = 6) versus Pattern B (n = 13) with Pattern B (P = 0.004). Both patients with intraoperative fractures displayed Pattern A before fracture and switched to Pattern B immediately after fracture

Sakai et al. (2022) [15]

Acoustic

0 (0%)

When the maximum peak frequency stays within the range of ± 0.5 kHz three times in a row, the stem was deemed fixed and the miniaturized analysis system provided a warning that further hammering would cause a fracture

No fractures were detected. Also, no implants had evidence of aseptic loosening or instability at the five-year follow-up

Sakai et al. (2021) [16]

Acoustic

0 (0%)

Stability and cup fixation were defined when the maximum peak frequency changed within ± 0.5 kHz or less in three consecutive blows

The mean stable maximum peak frequency was 4.42 ± 4.02 kHz. A constant maximum peak frequency continued 3.27 ± 0.47 times. Peak frequency repeats when appropriate fixation is acquired during surgery, suggesting that intraoperative fracture can be prevented by stopping hammering at the time the peak frequency converges within ± 0.5 kHz

Mulier et al

(2008) [4]

Vibration

1 (3.3%)

The amount of FRF change between insertion steps was evaluated by calculating PCCs between successive FRFs. A correlation between the FRFs of consecutive stages of R = (0.99 ± 0.01) was considered as the endpoint

Initially, as the stem was partially inserted, the peak of the FRF graph shifted towards frequencies associated with decreased fixation. Further hammering in one case led to an abnormal shape in the FRF graph, in which a small fracture was observed. The FRF's progression can be used to assess implant stability and detect the insertion endpoint. Any variation from the normal evolution of FRF graphs could serve as a warning for impending fracture

McConnell et al. (2018) [17]

Acoustic

1 (1%)

Impaction sounds of the first and last broaches were analyzed to identify prominent frequency bands. In all hips, the frequencies from the initial broach were still present during the impaction of subsequent broaches but at a lower amplitude. Cases were categorized according to the addition of a low-frequency band during subsequent broaching spectrographs contrasted with initial broaching

A low-frequency band was present from the first broach. Subsequent broaching with larger sizes generated a band of gradually increasing frequency and amplitude until the fracture occurred. The one femoral fracture observed brought a distinct sound alteration: immediately before bone fracture, the standing wave progressively gradually increased in frequency and then diminished