Aims. The aim of this retrospective study was to assess the incidence of early periprosthetic femoral fracture (PFF) associated with Charnley-Kerboull (CK) femoral components cemented according to the ‘French paradox’ principles through the Hueter anterior approach (HAA) in patients older than 70 years. Methods. From a prospectively collected database, all short CK femoral components implanted consecutively from January 2018 to May 2022 through the HAA in patients older than 70 years were included. Exclusion criteria were age below 70 years, use of cementless femoral component, and approaches other than the HAA. A total of 416 short CK prostheses used by 25 surgeons with various levels of experience were included. All patients had a minimum of one-year follow-up, with a mean of 2.6 years (SD 1.1). The mean age was 77.4 years (70 to 95) and the mean BMI was 25.3 kg/m. 2. (18.4 to 43). Femoral anatomy was classified according to Dorr. The measured parameters included canal flare index, morphological cortical index, canal-calcar ratio, ilium-ischial ratio, and anterior superior iliac spine to greater trochanter (GT) distance. Results. Among the 416 THAs, two PFFs (0.48% (95% confidence interval 0.13 to 1.74)) were observed, including one Vancouver type B2 fracture 24 days postoperatively and one intraoperative Vancouver type B1 fracture. Valgus malalignment and higher canal bone ratio were found to be associated with PFF. Conclusion. This study demonstrated that short CK femoral components cemented according to the French paradox were associated with a low rate of early PFF (0.48%) in patients aged over 70 years. Longer follow-up is warranted to further evaluate the rate of fracture that may occur during the bone remodelling process and with time. Cite this article: Bone Joint J 2024;106-B(3 Supple A):67–73

Background. There have been multiple techniques described to determine hindfoot alignment radiographically. The 2-dimensional nature of radiographs fails to take into account the contribution of the remainder of the foot to overall alignment. A new radiographic technique has been published in which the hindfoot alignment is calculated using the Ground Reaction Force Calcanea Offset. This technique accounts for the individual forefoot contribution to alignment, but is still limited by it´s 2-dimensional nature. The purpose of this study was to compare the hindfoot moment arm (HMA) described by Saltzman and the hindfoot alignment angle (HAA) described by Williamson, with a technique determining the ground reaction force calcaneal offset (GRF-CT) using 3-dimensional weight bearing CT Scans. Methods. The HMA, HAA, and GRF-CT 3-D weight bearing CT scans were measured by three different investigators. Each of these measurements were calculated twice on separate occasions by each investigator to determine the intra- and inter-observer reliability. Results. 104 patients underwent weight bearing hindfoot alignment radiographs and 3-dimensional weight bearing CT scans including 33 patients with varus and 71 patients with valgus hindfoot deformities. There was excellent intra- and inter-observer reliability with all three measurement techniques (P< 0.01), however the GRF-CT showed the best intra- and inter-observer reliability with the lowest standard deviation (P< 001). Conclusions. The GRF-CT technique is more reliable than traditional radiographic techniques for measuring the hindfoot alignment. While the intra- and inter-observer reliability is good for all three techniques, the GRF-CT technique resulted in the best intra- and inter-observer reliability with the lowest standard deviation. This technique provides the most accurate hindfoot alignment as it takes into account the effect of forefoot on overall alignment, preventing inaccuracies of projection and foot orientation in contrast to traditional radiographic techniques, which may be valuable in surgical decision making