Full-Quantitative Analysis of Cementless Stem Hammering Sound Changes During Total Hip Arthroplasty.

Full-quantitative characterization has not been performed to analyze changes in the hammering sound in cementless hip arthroplasty. We analyzed the frequency spectrum of the hammering sound during stem insertion for 20 cases of uncomplicated cementless total hip arthroplasty for osteoarthritis using a proximal-coated stem. The absolute sound pressure (Pa) and normalized sound pressure of each frequency bands in early and late stage of femoral stem insertion were determined by the Fast Fourier Transform analysis. The absolute sound pressures (Pa) of a majority of frequency bands was significantly higher in the late-stage stem insertion than in the early stage The 1.0–1.5-kHz frequency band showed a significant change in normalized sound pressure in all cases between the early and late stages of stem insertion (p=0.000). The femoral morphology and canal fill ratio were correlated with late stage normalized sound pressure in specific frequency bands. In the 5.0–5.5 kHz band, the Dorr A femoral morphology was significantly higher normalized sound pressure than those in the Dorr B (p=0.004). This study revealed the hammering sound frequency with full-quantitative value altered during cementless stem insertion. Frequency bands of 1.0–1.5 kHz, 5.0–5.5 kHz were the key bands for predicting stem fixation.

Influence of femoral morphology and canal fill ratio on early radiological and clinical outcomes of uncemented total hip arthroplasty using a fully coated stem

Aims The diversity of femoral morphology renders femoral component sizing in total hip arthroplasty (THA) challenging. We aimed to determine whether femoral morphology and femoral component filling influence early clinical and radiological outcomes following THA using fully hydroxyapatite (HA)-coated femoral components. Methods We retrospectively reviewed records of 183 primary uncemented THAs. Femoral morphology, including Dorr classification, canal bone ratio (CBR), canal flare index (CFI), and canal-calcar ratio (CCR), were calculated on preoperative radiographs. The canal fill ratio (CFR) was calculated at different levels relative to the lesser trochanter (LT) using immediate postoperative radiographs: P1, 2 cm above LT; P2, at LT; P3, 2 cm below LT; and D1, 7 cm below LT. At two years, radiological femoral component osseointegration was evaluated using the Engh score, and hip function using the Postel Merle d’Aubigné (PMA) and Oxford Hip Score (OHS). Results CFR was moderately correlated with CCR at P1 (r = 0.44; p < 0.001), P2 (r = 0.53; p < 0.001), and CFI at P1 (r = − 0.56; p < 0.001). Absence of spot welds (n = 3, 2%) was associated with lower CCR (p = 0.049), greater CFI (p = 0.017), and lower CFR at P3 (p = 0.015). Migration (n = 9, 7%) was associated with lower CFR at P2 (p = 0.028) and P3 (p = 0.007). Varus malalignment (n = 7, 5%), predominantly in Dorr A femurs (p = 0.028), was associated with lower CFR at all levels (p < 0.05). Absence of spot welds was associated with lower PMA gait (p = 0.012) and migration with worse OHS (p = 0.032). Conclusion This study revealed that femurs with insufficient proximal filling tend to have less favourable radiological outcomes following uncemented THA using a fully HA-coated double-tapered femoral component. Cite this article: Bone Joint Res. 2020;9(4):182–191.