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  • 1
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    Online Resource
    Discharging the medial knee compartment: comparison of pressure distribution and kinematic shifting after implantation of an extra-capsular absorber system (ATLAS) and open-wedge high tibial osteotomy—a biomechanical in vitro analysis
    Springer Science and Business Media LLC ; 2022
    In:  Archives of Orthopaedic and Trauma Surgery Vol. 143, No. 6 ( 2022-06-14), p. 2929-2941
    Details
    In: Archives of Orthopaedic and Trauma Surgery, Springer Science and Business Media LLC, Vol. 143, No. 6 ( 2022-06-14), p. 2929-2941
    Abstract: Young and active patients suffering early degenerative changes of the medial compartment with an underlying straight-leg axis do face a therapeutical gap as unloading of the medial compartment cannot be achieved by high tibial osteotomy. Extracapsular absorbing implants were developed to close this existing therapeutical gap. Purpose of the present cadaveric biomechanical study was to compare the unloading effect of the knee joint after implantation of an extra-articular absorber system (ATLAS) in comparison to open-wedge high tibial osteotomy (OW-HTO) under physiological conditions. The hypothesis of the study was that implantation of an extra-capsular absorber results in an unloading effect comparable to the one achievable with OW-HTO. Methods Eight fresh-frozen cadaveric knees were tested under isokinetic flexion–extension motions and physiological loading using a biomechanical knee simulator. Tibiofemoral area contact and peak contact pressures were measured using pressure-sensitive film in the untreated medial compartment. The tibiofemoral superior–inferior, latero-medial translation and varus/valgus rotation were measured with a 3D tracking system Polaris. Pressures and kinematics changes were measured after native testing, ATLAS System implantation and OW-HTO (5° and 10° correction angles) performed with an angular stable internal fixator (TomoFix). Results The absorber device decreased the pressure in the medial compartment near full extension moments. Implantation of the ATLAS absorbing system according to the manufacturers’ instruction did not result in a significant unloading effect. Deviating from the surgery manual provided by the manufacturer the implantation of a larger spring size while applying varus stress before releasing the absorber resulted in a significant pressure diminution. Contact pressure decreased significantly Δ0.20 ± 0.04 MPa p  = 0.044. Performing the OW-HTO in 5° correction angle resulted in significant decreased contact pressure (Δ0.25 ± 0.10 MPa, p  = 0.0036) and peak contact pressure (Δ0.39 ± 0.38 MPa, p  = 0.029) compared with the native test cycle. With a 10° correction angle, OW-HTO significantly decreased area contact pressure by Δ0.32 ± 0.09 MPa, p  = 0.006 and peak contact pressure by Δ0.48 ± 0.12 MPa, p  = 0.0654 compared to OW-HTO 5°. Surgical treatment did not result in kinematic changes regarding the superior–inferior translation of the medial joint section. A significant difference was observed for the translation towards the lateral compartment for the ATLAS system Δ1.31 ± 0.54 MPa p  = 0.022 and the osteotomy Δ3.51 ± 0.92 MPa p  = 0.001. Furthermore, significant shifting varus to valgus rotation of the treated knee joint was verified for HTO 5° about Δ2.97–3.69° and for HTO 10° Δ4.11–5.23° (pHTO 5 = 0.0012; pHTO 10 = 0.0007) over the entire extension cycle. Conclusion OW-HTO results in a significant unloading of the medial compartment. Implantation of an extra-capsular absorbing device did not result in a significant unloading until the implantation technique was applied against the manufacturer’s recommendation. While the clinical difficulty for young and active patients with straight-leg axis and early degenerative changes of the medial compartment persists further biomechanical research to develop sufficient unloading devices is required.
    Type of Medium: Online Resource
    ISSN: 1434-3916
    URL: Article
    DOI: 10.1007/s00402-022-04496-0
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2022
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  • 2
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    Long-term cost-effectiveness of matrix-associated chondrocyte implantation in the German health care system: a discrete event simulation
    Springer Science and Business Media LLC ; 2022
    In:  Archives of Orthopaedic and Trauma Surgery Vol. 143, No. 3 ( 2022-01-22), p. 1417-1427
    Details
    In: Archives of Orthopaedic and Trauma Surgery, Springer Science and Business Media LLC, Vol. 143, No. 3 ( 2022-01-22), p. 1417-1427
    Abstract: Cartilage defects in the knee can be caused by injury, various types of arthritis, or degeneration. As a long-term consequence of cartilage defects, osteoarthritis can develop over time, often leading to the need for a total knee replacement (TKR). The treatment alternatives of chondral defects include, among others, microfracture, and matrix-associated autologous chondrocyte implantation (M-ACI). The purpose of this study was to determine cost-effectiveness of M-ACI in Germany with available mid- and long-term outcome data, with special focus on the avoidance of TKR. Materials and methods We developed a discrete-event simulation (DES) that follows up individuals with cartilage defects of the knee over their lifetimes. The DES was conducted with a status-quo scenario in which M-ACI is available and a comparison scenario with no M-ACI available. The model included 10,000 patients with articular cartilage defects. We assumed Weibull distributions for short- and long-term effects for implant failures. Model outcomes were costs, number of TKRs, and quality-adjusted life years (QALYs). All analyses were performed from the perspective of the German statutory health insurance. Results The majority of patients was under 45 years old, with defect sizes between 2 and 7 cm 2 (mean: 4.5 cm 2 ); average modeled lifetime was 48 years. In the scenario without M-ACI, 26.4% of patients required a TKR over their lifetime. In the M-ACI scenario, this was the case in only 5.5% of cases. Thus, in the modeled cohort of 10,000 patients, 2700 TKRs, including revisions, could be avoided. Patients treated with M-ACI experienced improved quality of life (22.53 vs. 21.21 QALYs) at higher treatment-related costs (18,589 vs. 14,134 € /patient) compared to those treated without M-ACI, yielding an incremental cost‐effectiveness ratio (ICER) of 3376 € /QALY. Conclusion M-ACI is projected to be a highly cost‐effective treatment for chondral defects of the knee in the German healthcare setting.
    Type of Medium: Online Resource
    ISSN: 1434-3916
    URL: Article
    DOI: 10.1007/s00402-021-04318-9
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2022
    detail.hit.zdb_id: 1458452-9
    Location Call Number Limitation Availability
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