RESUMEN
We have been investigating analysis of knee joint vibration or vibroarthrographic (VAG) signals as a potential tool for noninvasive diagnosis and monitoring of cartilage pathology. In this paper, we present a comprehensive comparative study of different parametric representations of VAG signals. Dominant poles and cepstral coefficients were derived from autoregressive models of adaptively segmented VAG signals. Signal features and a few clinical features were used as feature vectors in pattern classification experiments based on logistic regression analysis and the leave-one-out method. The results using 51 normal and 39 abnormal signals indicated the superior performance of cepstral coefficients in VAG signal classification with an accuracy rate of 75.6%. With 51 normal and 20 abnormal signals limited to chondromalacia patella, cepstral coefficients again gave the highest accuracy rate of 85.9%.
Asunto(s)
Artrografía/métodos , Traumatismos de la Rodilla/diagnóstico , Articulación de la Rodilla/fisiopatología , Modelos Lineales , Procesamiento de Señales Asistido por Computador , Algoritmos , Auscultación , Humanos , Artropatías/diagnóstico , Modelos Logísticos , Monitoreo Fisiológico/instrumentación , Monitoreo Fisiológico/métodos , Reconocimiento de Normas Patrones Automatizadas , Valores de Referencia , VibraciónRESUMEN
The purpose of this study was to assess ultrasonographic image changes in the patellar tendon after removal of its central one third for anterior cruciate ligament reconstruction. Fourteen patellar tendons in 14 patients were assessed preoperatively and at 2 weeks, 4 weeks, 2 months, 6 months, and 12 months postoperatively. With time, the entire donor tendon became enlarged, hypoechoic, and inhomogeneous compared with the presurgical state. Tendons enlarged maximally in anteroposterior thickness by 2 months and then began to diminish, remaining two times their original anteroposterior thickness by 12 months and never returning to their preoperative appearance. The margins of the defect became indistinct over time. In the donor patellar tendon, abnormal echogenicity was profound and persisted up to 1 year after surgery. Ultrasonographic imaging has the ability to evaluate the postoperative patellar tendon over time and to monitor the normal changes seen with healing.
Asunto(s)
Ligamento Cruzado Anterior/cirugía , Rótula/diagnóstico por imagen , Tendones/diagnóstico por imagen , Adulto , Femenino , Estudios de Seguimiento , Humanos , Estudios Longitudinales , Masculino , Rótula/cirugía , Cuidados Posoperatorios , Tendones/trasplante , Ultrasonografía , Cicatrización de HeridasRESUMEN
OBJECTIVE: To establish whether there is consensus in the areas of definition, classification, assessment, diagnostic tests, and management of anterior knee pain. DATA SOURCES: A Medicine search for the years 1988-1995 was performed using the terms patellofemoral joint, knee joint and pain, injury and rehabilitation, and anterior knee pain. In addition, references from selected papers were examined. STUDY SELECTION: A total of 77 references specifically related to anterior knee pain were reviewed in the areas of definition, classification, assessment, diagnostic tests, and management. Although a small number of these papers were analytic in their study design, most of the papers reviewed were descriptive. DATA EXTRACTION: Definitive statements on anterior knee pain in the areas noted herein were extracted and summarized. Similar statements were then grouped as indicative of general consensus. Independent and divergent statements were also summarized for each area of anterior knee pain. DATA SYNTHESIS: Most of the literature related to anterior knee pain is subjective in nature and demonstrates limited consensus among experts. There is no generally accepted definition or classification of anterior knee pain. There was some agreement on the assessment, use of diagnostic tests, and management of anterior knee pain, but there are no definitive or objective management outcome criteria. CONCLUSIONS: The scientific literature on anterior knee pain is sparse. This review supports a need for the development of consensus guidelines for anterior knee pain. A consensus approach to anterior knee pain could result in the more efficient use of high-yield diagnostic tests, the use of more effective and standardized protocols for assessment and treatment, increased patient satisfaction, and recommendations on fitness counseling and early prevention.
Asunto(s)
Traumatismos de la Rodilla/diagnóstico , Traumatismos de la Rodilla/terapia , Manejo del Dolor , Dolor/diagnóstico , Pruebas Diagnósticas de Rutina , Guías como Asunto , Humanos , Traumatismos de la Rodilla/complicaciones , Dolor/etiología , Examen Físico , PronósticoRESUMEN
Interpretation of vibrations or sound signals emitted from the patellofemoral joint during movement of the knee, also known as vibroarthrography (VAG), could lead to a safe, objective, and non-invasive clinical tool for early detection, localisation, and quantification of articular cartilage disorders. In this study with a reasonably large database of VAG signals of 90 human knee joints (51 normal and 39 abnormal), a new technique for adaptive segmentation based on the recursive least squares lattice (RLSL) algorithm was developed to segment the non-stationary VAG signals into locally-stationary components; the stationary components were then modelled autoregressively, using the Burg-Lattice method. Logistic classification of the primary VAG signals into normal and abnormal signals (with no restriction on the type of cartilage pathology) using only the AR coefficients as discriminant features provided an accuracy of 68.9% with the leave-one-out method. When the abnormal signals were restricted to chondromalacia patella only, the classification accuracy rate increased to 84.5%. The effects of muscle contraction interference (MCI) on VAG signals were analysed using signals from 53 subjects (32 normal and 21 abnormal), and it was found that adaptive filtering of the MCI from the primary VAG signals did not improve the classification accuracy rate. The results indicate that VAG is a potential diagnostic tool for screening for chondromalacia patella.
Asunto(s)
Cartílago Articular/fisiopatología , Articulación de la Rodilla/fisiopatología , Procesamiento de Señales Asistido por Computador , Sonido , Adulto , Enfermedades de los Cartílagos/diagnóstico , Humanos , VibraciónRESUMEN
This paper proposes a noninvasive method to diagnose chondromalacia patella at its early stages by recording knee vibration signals (also known as vibroarthrographic or VAG signals) over the mid-patella during normal movement. An adaptive segmentation method was developed to segment the nonstationary VAG signals. The least squares modeling method was used to reduce the number of data samples to a few model parameters. Model parameters along with a few clinical parameters and a signal variability parameter were then used as discriminant features for screening VAG signals by applying logistic and discriminant algorithms. The system was trained using ten normal and eight abnormal signals. It correctly screened a separate test set of ten normal and eight abnormal signals except for one normal signal. The proposed method should find use as an alternative technique for diagnosis of knee joint pathology or as a test before arthroscopy or major knee surgery.
Asunto(s)
Enfermedades de los Cartílagos/diagnóstico , Diagnóstico por Computador , Electrofisiología/métodos , Articulación de la Rodilla/fisiología , Modelos Lineales , Rótula , Procesamiento de Señales Asistido por Computador , Algoritmos , Análisis de Fourier , Humanos , Análisis de los Mínimos Cuadrados , Movimiento/fisiología , Valores de Referencia , VibraciónRESUMEN
This paper proposes non-invasive techniques to localize sound or vibroarthrographic (VAG) signal sources in human knee joints. VAG signals from normal subjects, patients who subsequently underwent arthroscopy, and cadavers with arthroscopically-created lesions, obtained by stimulation with a finger tap over the mid-patella and swinging movement of the leg, were analyzed for time delays using cross-correlation functions for source localization. Correct results were obtained for 13 of the 14 subjects tested by finger stimulation, and for 11 of the 12 subjects whose VAG signals during swinging movement were analyzed. The techniques could be valuable in the diagnosis and treatment of knee pathology before and after joint surgery or drug therapy.
Asunto(s)
Auscultación/métodos , Cartílago Articular/patología , Articulación de la Rodilla/patología , Vibración , Artroscopía , Auscultación/instrumentación , Auscultación/estadística & datos numéricos , Cadáver , Enfermedades de los Cartílagos/patología , Análisis de Fourier , Humanos , Proyectos Piloto , Rango del Movimiento Articular , Valores de Referencia , Procesamiento de Señales Asistido por Computador/instrumentación , Factores de TiempoRESUMEN
Clinical methods used at present for the diagnosis of cartilage pathology in the knee are invasive in nature, and carry some risks. There exists a need for the development of a safe, objective, noninvasive method for early detection, localization, and quantification of cartilage pathology in the knee. This paper investigates the possibility of developing such a method based on an analysis of vibrations produced by joint surfaces rubbing against one another during normal movement. In particular, the method of modeling by linear prediction is used for adaptive segmentation and parameterization of knee vibration signals. Dominant poles are extracted from the model system function for each segment based on their energy contributions and bandwidths. These dominant poles represent the dominant features of the signal segments in the spectral domain. Two-dimensional feature vectors are then constructed using the first dominant pole and the ratio of power in the 40-120 Hz band to the total power of the segment. The potential use of this method to distinguish between vibrations produced by normal volunteers and patients known to have cartilage pathology (chondromalacia) is discussed.