Research Article| Volume 29, P134-141, March 2021

Focal articular surface replacement of knee lesions after failed cartilage repair using focal metallic implants: A series of 132 cases with 4-year follow-up

Published:February 18, 2021DOI:



      Focal articular lesions of the knee can be treated using several different techniques with generally good results, but failures are difficult to manage. Focal articular surface replacement (FASR) using metal implants could be a promising technique that allows defect geometry matching, congruency restoration and defect propagation prevention.


      132 patients were included who underwent FASR between January 2009 and December 2013. Three different implants were used: 1. HemiCAP®; 2. UniCAP® and 3. HemiCAP® PF Classic for trochlear lesions. Primary outcome parameter was knee function assessed by Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score with a 4-year follow-up, secondary outcomes included survivorship and complications. Statistical analyses were performed using GraphPad Prism.


      For all 132 surgeries combined (102 HemiCAP®, 11 UniCAP® and 19 HemiCAP® PF Classic implants), WOMAC scores significantly improved from 6 weeks onward until the end of the study (p < 0.001 for all time points). 4-year survival rate was 97.7%, and a re-operation rate of 12.1% was found. The HemiCAP® group revealed a slower WOMAC improvement in patients aged ≥40 years, combined with a trend towards lower final WOMAC scores and a higher re-operation rate in patients with a BMI ≥ 25.


      This report shows good to excellent clinical results of FASR as a salvage procedure after failed cartilage repair, with a low re-operation rate and a high survival of 97.7% at 4-year follow-up. Although longer follow-up is required, this could be a valuable treatment option in these challenging cases, without limiting future options for surgical interventions when deemed necessary.


      To read this article in full you will need to make a payment

      Purchase one-time access:

      Academic & Personal: 24 hour online accessCorporate R&D Professionals: 24 hour online access
      One-time access price info
      • For academic or personal research use, select 'Academic and Personal'
      • For corporate R&D use, select 'Corporate R&D Professionals'


      Subscribe to The Knee
      Already a print subscriber? Claim online access
      Already an online subscriber? Sign in
      Institutional Access: Sign in to ScienceDirect


        • Åroøen A.
        • Løken S.
        • Heir S.
        • Alvik E.
        • Ekeland A.
        • Granlund O.G.
        • et al.
        Articular Cartilage Lesions in 993 Consecutive Knee Arthroscopies.
        Am J Sports Med. 2004;
        • Widuchowski W.
        • Widuchowski J.
        • Trzaska T.
        Articular cartilage defects: Study of 25,124 knee arthroscopies.
        Knee. 2007;
        • Heir S.
        • Nerhus T.K.
        • Røtterud J.H.
        • Løken S.
        • Ekeland A.
        • Engebretsen L.
        • et al.
        Focal cartilage defects in the knee impair quality of life as much as severe osteoarthritis: A comparison of knee injury and osteoarthritis outcome score in 4 patient categories scheduled for knee surgery.
        Am J Sports Med. 2010;
        • Ding C.
        • Garnero P.
        • Cicuttini F.
        • Scott F.
        • Cooley H.
        • Jones G.
        Knee cartilage defects: Association with early radiographic osteoarthritis, decreased cartilage volume, increased joint surface area and type II collagen breakdown.
        Osteoarthr Cartil. 2005;
        • Bekkers J.E.J.
        • Inklaar M.
        • Saris D.B.F.
        Treatment Selection in Articular Cartilage Lesions of the Knee: A Systematic Review.
        Am J Sports Med. 2009;
        • Camp C.L.
        • Stuart M.J.
        • Krych A.J.
        Current Concepts of Articular Cartilage Restoration Techniques in the Knee.
        Sports Health. 2014;
        • de Windt T.S.
        • Sorel J.C.
        • Vonk L.A.
        • Kip M.M.A.
        • Ijzerman M.J.
        • Saris D.B.F.
        Early health economic modelling of single-stage cartilage repair. Guiding implementation of technologies in regenerative medicine.
        J Tissue Eng Regen Med. 2017;
        • Rosa D.
        • Di Donato S.L.
        • Balato G.
        • D’Addona A.
        • Smeraglia F.
        • Correra G.
        • et al.
        How to manage a failed cartilage repair: A systematic literature review.
        Joints. 2017;
        • Pestka J.M.
        • Bode G.
        • Salzmann G.
        • Südkamp N.P.
        • Niemeyer P.
        Clinical outcome of autologous chondrocyte implantation for failed microfracture treatment of full-thickness cartilage defects of the knee joint.
        Am J Sports Med. 2012;
        • Müller P.E.
        • Gallik D.
        • Hammerschmid F.
        • Baur-Melnyk A.
        • Pietschmann M.F.
        • Zhang A.
        • et al.
        Third-generation autologous chondrocyte implantation after failed bone marrow stimulation leads to inferior clinical results.
        Knee Surgery, Sport Traumatol Arthrosc. 2020;
        • Minas T.
        • Gomoll A.H.
        • Rosenberger R.
        • Royce R.O.
        • Bryant T.
        Increased failure rate of autologous chondrocyte implantation after previous treatment with marrow stimulation techniques.
        Am J Sports Med. 2009;
        • Nahas S.
        • Al-Obaidi B.
        • Shearman A.
        • Hodgson H.
        • Nathwani D.
        Focal knee resurfacing.
        Orthop Trauma. 2019;
        • Fuchs A.
        • Eberbach H.
        • Izadpanah K.
        • Bode G.
        • Südkamp N.P.
        • Feucht M.J.
        Focal metallic inlay resurfacing prosthesis for the treatment of localized cartilage defects of the femoral condyles: a systematic review of clinical studies.
        Knee Surgery, Sport Traumatol Arthrosc. 2018;
        • Malahias M.A.
        • Chytas D.
        • Thorey F.
        The clinical outcome of the different hemiCAP and uniCAP knee implants: A systematic and comprehensive review.
        Orthop Rev (Pavia). 2018;
        • Pascual-Garrido C.
        • Daley E.
        • Verma N.N.
        • Cole B.J.
        A Comparison of the Outcomes for Cartilage Defects of the Knee Treated With Biologic Resurfacing Versus Focal Metallic Implants.
        Arthrosc - J Arthrosc Relat Surg. 2017;
        • Shanmugaraj A.
        • Coughlin R.P.
        • Kuper G.N.
        • Ekhtiari S.
        • Simunovic N.
        • Musahl V.
        • et al.
        Changing trends in the use of cartilage restoration techniques for the patellofemoral joint: a systematic review.
        Knee Surgery, Sport Traumatol Arthrosc. 2019;
        • Angst F.
        • Aeschlimann A.
        • Stucki G.
        Smallest detectable and minimal clinically important differences of rehabilitation intervention with their implications for required sample sizes using WOMAC and SF-36 quality of life measurement instruments in patients with osteoarthritis of the lower extremities.
        Arthritis Rheum. 2001;<384::aid-art352>;2-0
        • Laursen J.O.
        • Lind M.
        Treatment of full-thickness femoral cartilage lesions using condyle resurfacing prosthesis.
        Knee Surgery, Sport Traumatol Arthrosc. 2017;
        • Laursen J.O.
        Treatment of full-thickness cartilage lesions and early OA using large condyle resurfacing prosthesis: UniCAP®.
        Knee Surgery, Sport Traumatol Arthrosc. 2016;
        • Bollars P.
        • Bosquet M.
        • Vandekerckhove B.
        • Hardeman F.
        • Bellemans J.
        Prosthetic inlay resurfacing for the treatment of focal, full thickness cartilage defects of the femoral condyle: A bridge between biologics and conventional arthroplasty.
        Knee Surgery, Sport Traumatol Arthrosc. 2012;
        • Becher C.
        • Kalbe C.
        • Thermann H.
        • Paessler H.H.
        • Laprell H.
        • Kaiser T.
        • et al.
        Minimum 5-year results of focal articular prosthetic resurfacing for the treatment of full-thickness articular cartilage defects in the knee.
        Arch Orthop Trauma Surg. 2011;
        • Jeschke E.
        • Citak M.
        • Günster C.
        • Matthias Halder A.
        • Heller K.D.
        • Malzahn J.
        • et al.
        Are TKAs Performed in High-volume Hospitals Less Likely to Undergo Revision Than TKAs Performed in Low-volume Hospitals?.
        Clin Orthop Relat Res. 2017;
        • Laursen J.O.
        • Mogensen C.B.
        • Skjøt-Arkil H.
        UniCAP offers a long term treatment for middle-aged patients, who are not revised within the first 9 years.
        Knee Surgery, Sport Traumatol Arthrosc. 2019;
        • Zaslav K.
        • Cole B.
        • Brewster R.
        • DeBerardino T.
        • Farr J.
        • Fowler P.
        • et al.
        A prospective study of autologous chondrocyte implantation in patients with failed prior treatment for articular cartilage defect of the knee: Results of the study of the treatment of articular repair (STAR) clinical trial.
        Am J Sports Med. 2009;
        • Ogura T.
        • Bryant T.
        • Merkely G.
        • Mosier B.A.
        • Minas T.
        Survival Analysis of Revision Autologous Chondrocyte Implantation for Failed ACI.
        Am J Sports Med. 2019;
        • Gracitelli G.C.
        • Meric G.
        • Pulido P.A.
        • McCauley J.C.
        • Bugbee W.D.
        Osteochondral Allograft Transplantation for Knee Lesions after Failure of Cartilage Repair Surgery.
        Cartilage. 2015;
        • Dhollander A.A.M.
        • Almqvist K.F.
        • Moens K.
        • Vandekerckhove P.J.
        • Verdonk R.
        • Verdonk P.
        • et al.
        The use of a prosthetic inlay resurfacing as a salvage procedure for a failed cartilage repair.
        Knee Surgery, Sport Traumatol Arthrosc. 2015;
        • Çepni Ş.
        • Veizi E.
        • Tahta M.
        • Uluyardımcı E.
        • Abughalwa M.J.T.
        • Işık Ç.
        Focal metallic inlay resurfacing prosthesis in articular cartilage defects: short-term results of 118 patients and 2 different implants.
        Arch Orthop Trauma Surg. 2020;