Custom-Made Metaphyseal Sleeves in "Beyond" AORI III Defects for Revision Knee Arthroplasty-Proof of Concept and Short-Term Results of a New Technique

Abstract

Background: While off-the-shelf cones and sleeves yield good results in AORI type 2 and 3 defects in revision knee surgery, massive longitudinal defects may require a proximal tibia replacement. To achieve the best anatomical as well as biomechanical reconstruction and preserve the tibial tuberosity, we developed custom-made metaphyseal sleeves (CMSs) to reconstruct massive defects with a hinge knee replacement.

Methods: Between 2019 and 2022, 10 patients were treated in a single-center study. The indication for revision was aseptic loosening in five cases and periprosthetic joint infection in five cases. The mean number of previous revisions after the index operations was 7 (SD: 2; 4-12). A postoperative analysis was conducted to evaluate the functional outcome as well as the osteointegrative potential.

Results: Implantation of the CMS in rTKA was carried out in all cases, with a mean operation time of 155 ± 48 (108-256) min. During the follow-up of 23 ± 7 (7-31) months, no CMS was revised and revisions due to other causes were conducted in five cases. Early radiographic evidence of osseointegration was recorded using a validated method. The postoperative OKS showed a significant increase (p < 0.001), with a mean score of 24 (SD: 4; range: 14-31).

Conclusion: Custom-made metaphyseal sleeves show acceptable results in extreme cases. As custom-made components become more and more common, this treatment algorithm presents a viable alternative in complex rTKA.

Keywords: AORI; cone; custom-made; periprosthetic joint infection; proximal tibial replacement; revision knee arthroplasty; sleeve; tibial bone defect.

Figure 1

Exemplary surface analysis in a patient not included due to follow-up <6 months. In total, 41.70 cm² of 56.47 cm² (73%) in the CMS achieved osseus contact, compared to 19.48 cm² of 36.24 cm² (53%) in an optimally positioned cortical cone. The patient was allowed full weight bearing postoperatively and achieved a flexion of 0–10–75° 2 months postoperatively after simultaneous quadriceps augmentation.

Figure 2

Custom-made rasps (−5 mm and size-to-size) as well as the definitive implant.

Figure 3

Aseptic loosening in a 77-year-old female patient (case 2). The CT scans show the combined meta-/diaphyseal AORI III defect, the planned individual component, and the final postoperative implant positioning (purple implant). The yellow lines represent the planned off-set.

Figure 4

Case number 9, an 80-year-old male patient with a multi-pathogen PJI treated in a two-stage exchange, showing the extensive defect, the contact analysis, and the postoperative results.

Figure 5

Case number 10, a 71-year-old male patient with a Staphylococcus epidermidis PJI treated in a two-stage exchange. Image 1: perioperative defect. Image 2: tibial assembly with a small modular tibial platform fixed with 2 screws. The interface between the CMS and the tibial platform was augmented with PMMA, and additional screw fixation (e.g., 4 instead of 2) was considered. Image 3: final prosthesis assembly. Image 4: preoperative rotational measurement in a 3D model. Image 5: −5 mm and size-to-size rasps with a trial assembly. Image 6: digital planning of the prosthesis. The rotation was not yet corrected. Image 7: AP and lateral views with axis measurement. Extensor mechanism pilot holes are shown in the proximal CMS.