Customised bi-compartmental knee arthroplasty shows encouraging 3-year results: findings of a prospective, multicenter study



The purpose of this study was to assess the clinical and patient-reported outcomes of a customised, individually made (CIM) bi-compartmental knee arthroplasty (BKA).


A prospectively recruited cohort of 79 patients was implanted with a CIM-BKA (patello-femoral plus either medial or lateral tibio-femoral, iDuo G2 system, Conformis, Billerica MA) at eight centres in the US and Germany. Patients were assessed for the 2011 KSS, KOOS, and ROM pre-operatively and at 2 weeks, 6 weeks, 12 weeks, 1 year, and 2 years post-operatively.


The objective KSS score significantly improved from 69 at the pre-operative visit, to 94 at the 2-year post-operative time-point. Similar improvements were observed for the KSS function and satisfaction domains. Significant improvements from pre-operative levels were observed across all five domains of the KOOS. Two patients have undergone surgery to revise their CIM-BKA implant to total knees, resulting in a survivorship rate of 97.5% at an average follow-up of 2.6 years.


CIM-BKA compares favourably to published scores as well as revision rates for previously available monolithic OTS-BKA implants. CIM-BKA implants provide surgeons with a viable and patient-specific monolithic implant solution as an option for patients presenting with bi-compartmental disease, who might, otherwise, be treated by performing uni-condylar + patello-femoral joint or bicruciate sparing TKA surgeries. Longer follow-up and higher numbers have to be awaited for further validation of these encouraging early results.

Level of evidence

3b (individual case-controlled study).

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This study was externally funded by Conformis.

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Correspondence to J. Beckmann.

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Conflicts of interest

All authors of the multicenter study received honoraria for patient enrollment and honoraria as consultants of Conformis which might influence this work.

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IRB/Ethics Committee approval was obtained from all participating sites.

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All patients signed an informed consent prior to participating in the study.

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Beckmann, J., Steinert, A.F., Huber, B. et al. Customised bi-compartmental knee arthroplasty shows encouraging 3-year results: findings of a prospective, multicenter study. Knee Surg Sports Traumatol Arthrosc 28, 1742–1749 (2020).

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  • Bi-compartment
  • BKR
  • Customised
  • Individualised
  • Bicruciate retaining
  • Total knee replacement