Aims. Custom triflange acetabular components (CTACs) play an important role in reconstructive orthopaedic surgery, particularly in revision total hip arthroplasty (rTHA) and pelvic tumour resection procedures. Accurate CTAC positioning is essential to successful surgical outcomes. While prior studies have explored CTAC positioning in rTHA, research focusing on tumour cases and implant flange positioning precision remains limited. Additionally, the impact of intraoperative navigation on positioning accuracy warrants further investigation. This study assesses CTAC positioning accuracy in tumour resection and rTHA cases, focusing on the differences between preoperative planning and postoperative implant positions. Methods. A multicentre observational cohort study in Australia between February 2017 and March 2021 included consecutive patients undergoing acetabular reconstruction with CTACs in rTHA (Paprosky 3A/3B defects) or tumour resection (including Enneking P2 peri-acetabular area). Of 103 eligible patients (104 hips), 34 patients (35 hips) were analyzed. Results. CTAC positioning was generally accurate, with minor deviations in cup inclination (mean 2.7°; SD 2.84°), anteversion (mean 3.6°; SD 5.04°), and rotation (mean 2.1°; SD 2.47°). Deviation of the hip centre of rotation (COR) showed a mean vector length of 5.9 mm (SD 7.24). Flange positions showed small deviations, with the ischial flange exhibiting the largest deviation (mean vector length of 7.0 mm; SD 8.65). Overall, 83% of the implants were accurately positioned, with 17% exceeding malpositioning thresholds. CTACs used in tumour resections exhibited higher positioning accuracy than rTHA cases, with significant differences in inclination (1.5° for tumour vs 3.4° for rTHA) and rotation (1.3° for tumour vs 2.4° for rTHA). The use of intraoperative navigation appeared to enhance positioning accuracy, but this did not reach statistical significance. Conclusion. This study demonstrates favourable CTAC positioning accuracy, with potential for improved accuracy through intraoperative navigation. Further research is needed to understand the implications of positioning accuracy on implant performance and long-term survival. Cite this article: Bone Jt Open 2024;5(4):260–268

Aims

Custom-made partial pelvis replacements (PPRs) are increasingly used in the reconstruction of large acetabular defects and have mainly been designed using a triflange approach, requiring extensive soft-tissue dissection. The monoflange design, where primary intramedullary fixation within the ilium combined with a monoflange for rotational stability, was anticipated to overcome this obstacle. The aim of this study was to evaluate the design with regard to functional outcome, complications, and acetabular reconstruction.

Problems associated with soft tissues of the stump and attachment of prosthetic devices for amputees remains a considerable problem. These problems are associated with the transmission of load through the soft tissues of the stump and difficulty in attaching the prosthetic device. Several devices have an osteointegrated transcutaneous prosthesis attached to the residual bone onto which an exo-prostheses is secured thereby transmitting load directly through the skeleton. Infection of these devices is a key issue. A biomimetic intraosseous transcutaneous device for amputees known as ITAP has been developed which is based on deer antler morphology. We have shown that in deer antlers the dermal and epithelial tissues are tethered by collagen fibres which originate from pores in the bone. In a caprine model where the soft tissue interface of ITAP is porous, dermal and epithelial integration occurs creating a seal and preventing infection. In two clinical veterinary cases an ITAP implant has been successfully used in trans-radial canine amputees. A human trans-humeral amputee who previously could not wear their exo-prosthesis has been treated with ITAP. The surgery was single stage procedure and involved the insertion of an uncemented intramedullary stem into the residual humerus. A porous flange structure positioned adjacent to the dermal tissue which had most of the hypodermis removed was used to promote soft tissue ingrowth. At two years' post-operation the skin seal has been maintained, there has been no incidence of infection, the patient wears their exo-prostheses for over 8 hours a day and has an almost complete range of shoulder motion. The use of ITAP device in selected cases may revolutionise the way amputees are surgically treated, lead to increased activity levels and more normal life styles in these patients