Early radiological outcomes of a fully porous bridging collar in lower-limb endoprosthetic reconstructions: a case-matched retrospective series to assess osseointegration

Jonathan Stevenson; M Ather Siddiqi; Vicky Sheehy; Ben Kendrick; Duncan Whitwell; Adrian Taylor; Gordon Blunn; Hasan R Mohammad; Atul F Kamath; Sofia Thoma

doi:10.1186/s42836-023-00230-2

Early radiological outcomes of a fully porous bridging collar in lower-limb endoprosthetic reconstructions: a case-matched retrospective series to assess osseointegration

Arthroplasty. 2024 Mar 2;6(1):17. doi: 10.1186/s42836-023-00230-2.

Authors

Affiliations

¹ Royal Orthopaedic Hospital NHS Foundation Trust, Bristol Road South, Northfield, Birmingham, B31 2AP, UK. Jonathan.stevenson@nhs.net.
² Aston University Medical School, Aston University, Birmingham, B4 7ET, UK. Jonathan.stevenson@nhs.net.
³ Nuffield Orthopaedic Centre, Oxford University Hospitals Trust, Windmill Road, Oxford, OX3 7LD, UK.
⁴ School of Pharmacy and Biomedical Sciences, University of Portsmouth, St. Michaels Building, White Swan Road, Portsmouth, PO1 2DT, UK.
⁵ Bart's Bone Joint Health, Bart's and the London School of Medicine and Dentistry, Blizard Institute, 4 Newark St., London, E1 2AT, UK.
⁶ Cleveland Clinic Foundation, Orthopaedic and Rheumatologic Institute, 9500 Euclid Avenue A40, Cleveland, OH, 44195, USA.
⁷ Royal Orthopaedic Hospital NHS Foundation Trust, Bristol Road South, Northfield, Birmingham, B31 2AP, UK.

Abstract

Background: Limb-salvage surgery involving the utilization of endoprosthetic replacements is commonly employed following segmental bone resection for primary and secondary bone tumors. This study aimed to evaluate whether a fully porous bridging collar promotes early osseous integration in endoprosthetic replacements.

Methods: We undertook a retrospective review of all lower-limb endoprostheses utilizing a fully porous endosteal bridging collar design. We matched this cohort with a conventional extra-osteal non-porous fully hydroxyapatite-coated grooved collar cohort according to surgical indication, implant type, resection length, age, and follow-up time. At 6, 12, and 24 months post-implantation, radiographs were assessed for the number of cortices with or without osseointegration on orthogonal radiographs. Each radiograph was scored on a scale of -4 to + 4 for the number of cortices bridging the ongrowth between the bone and the collar of the prosthesis. Implant survival was estimated using the Kaplan-Meier method, and the mean number of osseointegrated cortices at each time point between the collar designs was compared using a paired t-test.

Results: Ninety patients were retrospectively identified and analyzed. After exclusion, 40 patients with porous bridging collars matched with 40 patients with conventional extra-osteal non-porous collars were included in the study (n = 80). The mean age was 63.4 years (range 16-91 years); there were 37 males and 43 females. The groups showed no difference in implant survival (P = 0.54). The mean number of cortices with radiographic ongrowth for the porous bridging collar and non-porous collar groups was 2.1 and 0.3, respectively, at 6-month (P < 0.0001), 2.4 and 0.5, respectively, at 12-month (P = 0.044), and 3.2 and -0.2, respectively, at 24-month (P = 0.18) radiological follow-up.

Conclusion: These findings indicate that fully porous bridging collars increased the number of cortices, with evidence of bone ongrowth between 6 and 24 months post-implantation. By contrast, extra-osteal collars exhibited reduced evidence of ongrowth between 6 and 24 months post-implantation. In the medium term, the use of a fully porous bridging collar may translate to a reduced incidence of aseptic loosening.

Keywords: Aseptic loosening; Bone ongrowth; Endoprosthetic replacement; Porous collar.