Evaluating polyethylene, polyether-ether-ketone, and metal-on-metal locking mechanism survival in Modular Universal Tumour and Revision System knee reconstructions for oncological indications

The Bone & Joint Journal, vol. 107-B, pp. 239–245

Abstract

Aims: Over time, the locking mechanism of Modular Universal Tumour and Revision System (MUTARS) knee arthroplasties changed from polyethylene (PE) to polyether-ether-ketone Optima (PEEK) and metal-on-metal (MoM) in an attempt to reduce the risk of mechanical failure. In this study, we aimed to assess the cumulative incidence of locking mechanism revision for symptomatic instability by type of material, and assess potential associated risk factors. Methods: The MUTARS Orthopaedic Registry Europe was used for a retrospective review of 316 patients (54% male (n = 170), median age 44 years (IQR 23 to 61)) who underwent a MUTARS knee arthroplasty for oncological indications between December 1995 and January 2023. The minimum follow-up was 12 months, and the median follow-up was 7.9 years (IQR 3.3 to 13.0). A competing risk model was used to estimate the cumulative incidence of first locking mechanism revision with death and revision for any other reason as competing events. Possible risk factors were assessed employing a univariate cause-specific hazards regression model. Results: Symptomatic instability of the hinge or locking mechanism due to wear (n = 20) or breakage (n = 14) occurred in 34 patients (11%): 9% of PE (n = 4/45), 20% of PEEK (n = 9/44), and 9% of MoM locking mechanisms (n = 21/227). The cumulative incidences of revision for instability due to wear or locking mechanism breakage at two, five, and ten years were 0%, 5% (95% CI 1 to 15), and 5% (95% CI 1 to 15) for PE, 5% (95% CI 1 to 14), 14% (95% CI 5 to 26), and 16% (95% CI 7 to 29) for PEEK, and 0%, 3% (95% CI 1 to 6), and 10% (95% CI 5 to 16) for MoM. With PE as the reference category, the cause-specific hazard ratio for PEEK and MoM were 3.6 (95% CI 1.1 to 11.9; p = 0.036) and 3.2 (95% CI 1.1 to 9.5; p = 0.043), respectively. Age, BMI, resection length, and extra-articular resections were not associated with the time to locking mechanism revision. Conclusion: Alterations in prosthetic materials have not decreased the revision risk for locking mechanism failure. Besides locking mechanism material, no other patient- or prosthesis-related risk factors for locking mechanism failure were identified. Improvement of the locking mechanism is warranted since revision exposes patients to the risk of serious secondary complications.

Authors 10

1. Richard E. Evenhuis Aachen Department of Orthopaedic Surgery

   Leiden University Medical Center

   Affiliation as printed

   Department of Orthopaedic Surgery, Leiden University Medical Center, Leiden, Netherlands

2. Michaël P. A. Bus Aachen Department of Orthopaedic Surgery

   Leiden University Medical Center

   Affiliation as printed

   Department of Orthopaedic Surgery, Leiden University Medical Center, Leiden, Netherlands

3. J. van Nes Aachen Department of Orthopaedic Surgery

   Leiden University Medical Center

   Affiliation as printed

   Department of Orthopaedic Surgery, Leiden University Medical Center, Leiden, Netherlands

4. Sebastian Gottfried Walter

   University Hospital Cologne

   Affiliation as printed

   Department of Orthopedic Surgery, Traumatology, and Plastic Surgery, University Hospital Cologne, Cologne, Germany

5. Jorge Cabrolier

   Instituto Traumatológico Dr. Teodoro Gebauer Weisser

   Affiliation as printed

   Department of Orthopaedic Surgery, Traumatological Institute Teodore Gebauer, Santiago, Chile

6. Marta F. Fiocco Aachen Department of Biomedical Science Section Medical Statistics

   Leiden University · Leiden University Medical Center · Princess Máxima Center

   Affiliation as printed

   Center for Pediatric Oncology, Princess Maxima Center, Utrecht, Netherlands

   Department of Biomedical Science, Section Medical Statistics, Leiden Universitair Medisch Center, Leiden, Netherlands

   Mathematical Institute Leiden University, Leiden, Netherlands

7. Robert J. P. van der Wal Aachen Department of Orthopaedic Surgery

   Leiden University Medical Center

   Affiliation as printed

   Department of Orthopaedic Surgery, Leiden University Medical Center, Leiden, Netherlands

8. Demiën Broekhuis Aachen Department of Orthopaedic Surgery

   Leiden University Medical Center

   Affiliation as printed

   Department of Orthopaedic Surgery, Leiden University Medical Center, Leiden, Netherlands

9. Simen Sellevold

   Oslo University Hospital

   Affiliation as printed

   Department of Orthopaedic Surgery, Oslo University Hospital, Oslo, Norway

10. Michiel A. J. van de Sande Aachen Department of Orthopaedic Surgery

    Leiden University Medical Center · Princess Máxima Center

    Affiliation as printed

    Center for Pediatric Oncology, Princess Maxima Center, Utrecht, Netherlands

    Department of Orthopaedic Surgery, Leiden University Medical Center, Leiden, Netherlands