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    Interventional procedure overview of focal resurfacing implants to treat articular cartilage damage in the knee

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    Safety summary

    Revisions and reoperations

    Note: revisions were typically to the same (or different) focal resurfacing implant, UKA, or TKA. The reasons for revision were not always described in the publications. Some of the reasons may have been because of a lack of efficacy, and others may have been because of complications. All revisions are presented in this section, regardless of the reasons for revision.

    In a registry analysis of 220 procedures, there was a cumulative revision of 27.6% (95% CI 22.1% to 34.1%) at 5 years follow up, and 49.5% (95% CI 41.8% to 57.8%) at 12 years follow up. All procedures captured in this registry were done using the HemiCAP range of prostheses (Australian Orthopaedic Association National Joint Replacement Registry, 2020).

    In a registry analysis of 379 implants, 5-year revision-free survival was 0.84 (95% CI 0.80 to 0.88) and 10-year revision-free survival was 0.80 (95% CI 0.75 to 0.84). Most implants captured by this registry were HemiCAP or UniCAP (95%), with a small proportion Episealer (5%) (Christensen, 2021).

    In the before-and-after study of 132 people, there were 3 people who had revisions, with an overall 4-year implant survival of 97.7%. A total of 16 reoperations were done, leading to an overall reoperation rate of 12.1%. All reoperations involved an arthroscopy. All procedures in this study were done with the HemiCAP/UniCAP implants (van Buul, 2021).

    In the retrospective cohort study of 118 people, 13 (11.0%) needed revision surgery. In multivariate regression analysis, the BioPoly implant was a statistically significant risk factor for revision surgery: adjusted HR (95% CI) 6.90 (1.04 to 45.73; p=0.045). However, this analysis may have been confounded because 3 of the revisions of the BioPoly implant were in people who experienced trauma leading to pain and implant loosening (Çepni, 2020). The reasons for revision were as follows:

    • BioPoly:

      • progressive pain after trauma, implant loosening, chondral lesions in the patellofemoral compartment, n=2

      • progressive pain after trauma, implant loosening, n=1

      • progressive arthritis in the lateral compartment, n=2

      • progressive arthritis in the medial compartment, n=2

      • infection, n=1.

    • HemiCAP:

      • generalised arthritis involving all compartments, n=2

      • progressive arthritis in the lateral compartment, n=1

      • progressive pain, implant loosening, generalized chondrolysis in all compartments, n=1

      • infection, n=1.

    In the before-and-after study of 33 people, 1 person had a revision because of the failure of osseointegration. All procedures in this study were done with the BioPoly implants (Nathwani, 2017).

    In a consecutive case series of 612 knees, a total of 14 (2.3%) had revisions over the 7-year follow-up period. Using Kaplan–Meier analysis, implant survivorship at 7 years was 95.95%. All procedures in this study were done with the Episealer implant (Ryd, 2021). The reasons for revision were as follows (some people had multiple reasons):

    • Pain, n=6

    • Disease progression, n=2

    • Multiple lesions, n=2

    • Implant was too small, n=2

    • Trauma after surgery, n=1

    • Metal allergy, n=1

    • Borderline indication, n=1

    • Tibial cartilage wear, n=1

    • Infection, n=1

    • Unknown, n=1

    • High tibial osteotomy failed, n=1

    In the before-and-after study of 75 people, a total of 3 people had revisions, 2 during the 24-month follow up, and 1 at 27 months. This resulted in an overall revision rate of 4%. All procedures in this study were done with the Episealer implant (Holz, 2021). The reasons for revision were as follows:

    • Atypical lesion with significant bone marrow oedema condyle before surgery, did not improve after surgery and re-presented with increased pain, n=1

    • Cysts persisting from previous OATS plugs, symptoms did not improve after surgery, n=1

    • Severe pain, loose implant, infection, n=1

    Complications and adverse events

    Note: This section contains complications and adverse events that were not reported to be reasons for revision. The previous section describes all reasons for revision, some of which were complications.

    Deep vein thrombosis

    The before-and-after study of 75 people reported 1 case of deep vein thrombosis (Holz, 2021).

    Pain

    The before-and-after study of 33 people reported 9 cases of knee pain (arthralgia), 4 of which were localised to the contralateral compartment. This adverse event was considered unrelated to the device (Nathwani, 2017).

    The before-and-after study of 75 people reported 1 case of painful mechanical clicking (Holz, 2021).

    Infection

    The before-and-after study of 33 people reported 1 case of wound infection. This adverse event was considered unrelated to the device (Nathwani, 2017).

    Stiffness

    The before-and-after study of 33 people reported 1 case of stiffness. This adverse event was considered unrelated to the device (Nathwani, 2017).

    Swelling

    The before-and-after study of 33 people reported 2 cases of swelling. This adverse event was considered unrelated to the device (Nathwani, 2017).

    Clicking and crepitation

    The before-and-after study of 33 people reported 3 cases of crepitation. This adverse event was considered unrelated to the device (Nathwani, 2017).

    The before-and-after study of 75 people reported 1 case of painful mechanical clicking (Holz, 2021).

    Loose cartilage body

    The before-and-after study of 33 people reported 1 case of loose cartilage body. This adverse event was considered unrelated to the device (Nathwani, 2017).

    Anecdotal and theoretical adverse events

    In addition to safety outcomes reported in the literature, professional experts are asked about anecdotal adverse events (events which they have heard about) and about theoretical adverse events (events which they think might possibly occur, even if they have never happened).

    For this procedure, the professional experts did not list any theoretical or anecdotal adverse events.