A model-based approach to measure the minimum joint space width of total knee replacements in standard radiographs

• Published in: Journal of biomechanics Vol. 45; no. 12; pp. 2171 - 2175
• Main Authors: van IJsseldijk, E.A, Valstar, E.R, Stoel, B.C, Nelissen, R.G.H.H, Kaptein, B.L
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 09.08.2012; Elsevier; Elsevier Limited
• Subjects: Accuracy; Arthroplasty, Replacement, Knee - methods; Biological and medical sciences; Biomedical materials; Computerized, statistical medical data processing and models in biomedicine; Equipment Failure Analysis - methods; Humans; Joint replacement surgery; Knee Joint - diagnostic imaging; Knee Prosthesis; Male; Measurement methods; Medical sciences; Methods; Minimum joint space width; Model-based analysis; Models and simulation; Models, Biological; Observer Variation; Orthopedic surgery; Phantoms, Imaging; Physical Medicine and Rehabilitation; Polyethylene; Polyethylene wear measurements; Prostheses; Prosthesis Design; Radiographs; Radiography; Reproducibility; Sensors; Surgery (general aspects). Transplantations, organ and tissue grafts. Graft diseases; Surgical implants; Total knee arthroplasty; Wear; Model-based analysis; Total knee arthroplasty; Minimum joint space width; Polyethylene wear measurements; Human; Polyethylene; Radiodiagnosis; Exploration; Modeling; Joint space; Biomechanics; Radiography; Orthopedic surgery; Treatment; Reproducibility; Wear; Biomedical engineering
• ISSN: 0021-9290; 1873-2380
• DOI: 10.1016/j.jbiomech.2012.05.012

Abstract Excessive wear in total knee arthroplasty is detected by measuring the minimum joint space width (mJSW) in anterioposterior radiographs. The accuracy of conventional measurement methods is limited and can be improved using model-based techniques. In this study, the model-based wear measurement (MBWM) is introduced. Its accuracy and reproducibility are assessed and compared to the conventional measurement. Forty anterioposterior radiographs were obtained of a knee prosthesis using a phantom setup. Both measurement methods were applied and the accuracy and precision were compared. The reproducibility was calculated with inter- and intra-observer experiments. Three observers measured the mJSW in 30 clinical radiographs with both the conventional measurement and the MBWM and repeated this after 6 weeks. The experiments were conducted with a NexGen mobile bearing and fixed bearing prostheses. In the phantom experiment, the accuracy (mean of the absolute error) was significantly higher ( t -test, p <0.01) for the MBWM as for the conventional measurement (0.15 mm versus 0.43 mm, 0.14 mm versus 0.35 mm for the mobile and fixed bearing, respectively). The standard deviation of the measurements is the smallest for the MBWM measurement for both prosthesis types (0.16 mm versus 0.47 mm, Levene's test, p <0.01). In the reproducibility experiment, both the intra- and inter-observer agreements were higher for the MBWM than for the conventional method. The results show that the MBWM is superior to the conventional measurement in both accuracy and reproducibility. Although the use of a phantom experiment poses some limitations in conveying the findings to clinical practice, this improved mJSW measurement can lead to better wear detection for surgery decisions and research purposes.