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. 2020 May 16;9(4):182-191.
doi: 10.1302/2046-3758.94.BJR-2019-0149.R2. eCollection 2020 Apr.

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

Adrien D'Ambrosio  1 , Lisa Peduzzi  2 , Olivier Roche  1 , Hugo Bothorel  3 , Mo Saffarini  3 , François Bonnomet  1
Affiliations

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

Adrien D'Ambrosio et al. Bone Joint Res. .

Abstract

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.

Keywords: Canal fill ratio; Femoral morphology; Filling; Fully coated stem; Osteointegration; Total hip arthroplasty.

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Conflict of interest statement

Conflict of interest statement: O. Roche and F. Bonnomet report personal fees from SERF related to this study. H. Bothorel and M. Saffarini report fees from SERF related to the statistical analysis and manuscript preparation for this study.

Figures

Fig. 1
Fig. 1
Study flowchart detailing initial cohort, exclusions, losses to follow-up, deaths, and final cohorts evaluated clinically and radiographically. AVN, avascular necrosis; FNF, femoral neck fracture.
Fig. 2
Fig. 2
Frontal radiological measurements (taken from a 63-year-old male) of: femoral anatomical parameters, including canal bone ratio (CBR = e/f), canal flare index (CFI = a/e), and canal-calcar ratio (CCR = e/b); and canal fill ratios (CFR) at 2 cm above the lesser trochanter (P1 = a’/a), at the lesser trochanter (P2 = b’/b), 2 cm below the lesser trochanter (P3 = c’/c), and 7 cm below the lesser trochanter (D1 = d’/d).
Fig. 3
Fig. 3
Associations between femoral morphology, femoral component filling, postoperative osseointegration, and postoperative clinical outcomes.
See this image and copyright information in PMC

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