Osteophytes, juxta-articular radiolucencies and cancellous bone changes in the proximal tibia of patients with knee osteoarthritis.

OBJECTIVE: To determine differences in tibial cancellous bone organisation in knee osteoarthritis (OA) between the central weight-bearing region and juxta-articular radiolucencies adjacent to small, medium or large marginal osteophytes. METHODS: Patients with medial compartment OA (n = 60; F = 39), mean (SD) age 60.0 (9.7) years, and non-OA reference subjects (n = 21; F = 5), mean (SD) age 36.8 (11.5) years, had x4 macroradiographs digitised by laser scanner. Using a modified Osteoarthritis Research Society (OARS) Atlas, right and/or left knees were graded according to marginal osteophyte size into those with small (n = 30), medium (n = 30) or large (n = 27) marginal osteophytes, identified as OPH1, OPH2 and OPH3, respectively. Non-OA knees (n = 30) were anatomically normal. Computerised method of Fractal Signature Analysis (FSA) quantified differences in cancellous bone structure between non-OA and osteophyte subgroups at two regions of interest (ROIs); central weight-bearing and tibial margin. RESULTS: Compared to non-OA, vertical trabecular number increased significantly (P < 0.05) in all osteophyte subgroups (width range 0.12-1.14 mm) within both ROIs. In OPH3, this increase was significantly (P < 0.05) greater compared to OPH2 in the central ROI, and to OPH2 and OPH1 in the marginal ROI at most trabecular widths (0.12-1.14 mm). In the marginal ROI, compared to non-OA, horizontal trabeculae number decreased in all osteophyte subgroups. This decrease was significantly greater in OPH3 compared to OPH2 and OPH1 at small to medium trabecular widths (0.12-0.54 mm). CONCLUSION: Compared to disease associated bone loss at the central ROI of the tibia, the extent of juxta-articular bone loss appears to be associated with the size of the marginal osteophytes.

Differences in trabecular structure between knees with and without osteoarthritis quantified by macro and standard radiography, respectively.

OBJECTIVE: To compare the sensitivity of standard and macro-radiography for quantifying cancellous bone differences between subjects with and without medial compartment knee osteoarthritis (OA). METHODS: Patients with medial compartment knee OA (n=24) and non-OA reference subjects (n=10) had a standard and a macro-radiograph (x4 magnification) of one knee. Fractal Signature Analysis (FSA), a computerised image analysis technique, measured differences in cancellous bone structure between OA and non-OA tibiae in all radiographs. RESULTS: Compared to non-OA, FSA of vertical trabeculae in macro-radiographs increased significantly (P<0.05) in the OA group at several trabecular widths (0.30-0.60mm, 0.7 mm, 0.98-1.14 mm) and in standard radiographs at a single trabecular width (0.48 mm). CONCLUSION: Compared to standard radiography, increased spatial resolution of macro-radiography allowed greater detection of trabecular bone differences between OA and non-OA knees. Nonetheless, difference was also detected in standard radiographs.

Review of the anatomical and radiological differences between fluoroscopic and non-fluoroscopic positioning of osteoarthritic knees.

OBJECTIVE: To determine the differences in the radioanatomical appearance of the tibiofemoral compartment in knees radiographed in the fluoroscopic semiflexed, semiflexed MTP and fixed flexion methods compared to that obtained in the extended knee position. To assess the differences in the radiological procedures between the fluoroscopic and nonfluoroscopic semiflexed methods of radiography. METHODS: Based on anatomical principals to describe the differences in (1) the content of the joint space in knees radiographed in the extended and semiflexed positions and (2) the sectional plane for joint space width (JSW) measurement in radiographs of knees positioned in the extended, fluoroscopic guided semiflexed, MTP and fixed flexion positions. From published procedures to determine the factors that affect study costs, X-ray technologists operating time and film processing in fluoroscopic and nonfluoroscopic methods of radiography. RESULTS: Medial compartment JSW from semiflexed methods only accurately measures cartilage thickness. All semiflexed methods reproducibly reposition the joint within any one patient. The angle at the tibiofemoral joint varies little between patients in the fluoroscopic semiflexed, less in the MTP and more so in the fixed flexion positions; the latter is due to the effect weight-associated differences in thigh girth. The sectional plane of JSW measurement is generally similar within the three views. Compared to the fluoroscopic method the radiological procedures of the nonfluoroscopic techniques were less demanding. CONCLUSION: The MTP and fixed flexion methods are much easier to use than the fluoroscopic method. They reproducibly reposition the knee within patient knees and between knees in the MTP but less so in the fixed flexion view.

Comparison of fixed flexion, fluoroscopic semi-flexed and MTP radiographic methods for obtaining the minimum medial joint space width of the knee in longitudinal osteoarthritis trials.

OBJECTIVE: To compare three radiographic techniques (fluoroscopic semi-flexed [Fluoro], fixed flexion [FF], and semi-flexed metatarsophalangeal joint [MTP] views) for measuring medial joint space width (JSW) of the knee in longitudinal osteoarthritis (OA) trials and to identify the percentage of patients with detectable progression. DESIGN: Retrospective summary of the progression and variability of the change in JSW in knee OA. MATERIAL AND METHODS: Data from the placebo arms of three separate, structure modifying, knee OA trials were compared including gender, age, baseline JSW, change from baseline in JSW, duration of observation, and number and percent of patients with joint space narrowing of various degrees. Computer evaluation of the joint space at its narrowest point in the medial compartment was used in the studies. It is important to note that the narrowest joint space at baseline may not be in the same anatomic location at subsequent evaluations. No statistical tests were performed. RESULTS: The average observation times were 0.98, 0.68 and 0.82 years for the Fluoro, FF, and MTP studies, respectively. The amount of progression was different among the three studies. The Fluoro study showed the greatest magnitude of OA structural progression and the lowest variability. The Fluoro study was expected to show the greatest magnitude of structural progression since it was conducted for the longest duration. For all patients, the standard deviation of the change in JSW was 0.42, 0.63, and 0.53 mm for the Fluoro, FF, and MTP studies, respectively. The percent of patients with detectable progression was similar across studies. CONCLUSION: With these data, information was not sufficient to control for duration of observation and differences in inclusion criteria for the three study populations. Therefore, no definitive conclusions can be made regarding the degree of progression of OA over specific time intervals. However, the data indicate that all three studies contain a cohort of patients that exhibit detectable progression.

Cancellous bone changes in hip osteoarthritis: a short-term longitudinal study using fractal signature analysis.

OBJECTIVE: To quantify changes to the trabecular structure in the femoral heads of patients with hip osteoarthritis (OA). METHODS: Patients with OA (n=14; F=7), mean (standard deviation age) 50.6 (10.1) years, had macroradiographs at approximately x4 magnification at baseline and 18 months later using a standardized protocol. Following digitization, computerized measurement was obtained of minimum hip joint space width and fractal signature analysis (FSA) measured longitudinal changes separately in the principal compressive (vertical) and horizontal trabeculae at the region of interest within the centre of the head. RESULTS: The patient group had mean annual rate of joint space narrowing of 0.14+/-0.36 mm/yr. FSA detected no significant changes in horizontal trabeculae, whereas the larger principal compressive (vertical) trabeculae (0.96 mm to 1.02 mm) increased significantly in thickness and the fine to medium trabeculae (0.18 mm to 0.54 mm) decreased significantly in number. CONCLUSION: The increased thickness of the larger trabeculae within the compressive structural element of the femoral head is a response to the increase in stress associated with an overall loss of trabeculae in this region, suggesting the presence of an osteoporosis within the femoral head in OA patients.

Pattern of advancement in the zone of calcified cartilage detected in hand osteoarthritis.

OBJECTIVE: Using high definition macroradiography the pattern of advancement in the zone of calcified cartilage (termed a ZCC step) was detected in osteoarthritic hand joints of patients and compared to the joint space width (JSW) measurement. DESIGN: X5 macroradiographs were obtained of the osteoarthritic hands of 44 patients at baseline and at 18 months. The incidence of ZCC steps, identified as an advancement in the mineralized cartilage front into articular cartilage, was assessed at each articular surface. JSW was measured and was used to determine the difference in JSW between hands and groups of joints with and without ZCC steps at both X-ray visits. RESULTS: ZCC steps were found at the convex articular surfaces in only 42 (48%) hand joints in 28 (64%) patients. Here, ZCC steps were present in 36 joints in the non-dominant hand, compared with 30 joints in the dominant hand. In the former, they were present in 22 DIP, six PIP and eight MCP joints and in 12 DIP, eight PIP and 10 MCP joints in the dominant hand. By 18 months, new ZCC steps had formed in 15 hands with and 17 hands without previous ZCC steps. At both X-ray visits no statistically significant difference in JSW was found between the hands and joint groups with and without ZCC steps. CONCLUSION: In patients with ZCC steps, the pattern of distribution in the hand appeared to be related to that due to vascular changes, such as hyperlipidaemia, rather than to that associated with mechanical forces.

Advancement in the zone of calcified cartilage in osteoarthritic hands of patients detected by high definition macroradiography.

OBJECTIVE: High definition macroradiography permits the advancement in the zone of calcified cartilage (described as a ZCC step) to be detected in osteoarthritic (OA) hand joints of patients. The pattern of their incidence and distribution was determined and compared to the joint space width (JSW) measurement. DESIGN: Macroradiographs, x5 magnification, were obtained of the OA hands of 44 patients at baseline and at 18 months. The incidence of ZCC steps, identified as an advancement in the mineralized cartilage front into articular cartilage, was assessed at each articular surface. JSW was measured and was used to determine the difference in JSW between hands and groups of joints with and without ZCC steps at both X-ray visits. RESULTS: ZCC steps were only found at the convex articular surfaces in 42 (48%) of hand joints in 28 (64%) patients. Here, ZCC steps were present in 36 joints in the non-dominant hand compared to 30 joints in the dominant hand. In the former, they were present in 22 DIP, six PIP and eight MCP joints and in 12 DIP, 8 PIP and 10 MCP joints in the dominant hand. By 18 months new ZCC steps had formed in 15 hands with and 17 hands without previous ZCC steps. At both X-ray visits no statistically significant difference in JSW was found between the hands and joint groups with and without ZCC steps. CONCLUSION: Although ZCC steps and JSW loss were greater at the PIP joints, supporting a mechanical hypothesis for ZCC formation, their presence in joints, where JSW was larger, and their greater incidence in the non-dominant PIP joints, suggest that factors associated with vascular changes, related to subchondral bone remodeling, are responsible.¿copy¿

Current status of imaging procedures in the diagnosis, prognosis and monitoring of osteoarthritis.

X-ray, magnetic resonance imaging (MRI) and arthroscopy are the methods most widely used to assess the status of osteoarthritic joints. How do these methods compare? As diagnostic tools, what is the relative sensitivity of X-ray versus MRI, arthroscopy versus MRI and arthroscopy versus X-ray? Which imaging modalities can be used for predicting progression? Scintigraphy and MRI can assess the degree of cellular activity in the tissues of a joint, which may help in prognosis. Are the methods proven and are they reliable? Recommendations for clinical trials in knee osteoarthritis, state it is essential that reproducible radiographs are obtained for reliable assessment of progression. Two radiographic views of the knee have been proposed; which provides the more reliable assessment, the knee in extension or semi-flexed? Compared with standard radiography, does microfocal radiography make a difference to patient numbers required for drug trials?

Protocols for precise radio-anatomical positioning of the tibiofemoral and patellofemoral compartments of the knee.

Quantitative assessment of radiographic features, in particular joint space width, are important in the diagnosis and treatment of knee osteoarthritis (OA). Protocols defining radiographic procedures are essential to maintain quality control and hence reliable and reproducible measurement of these features. Criteria governing variability in radiographic procedures are discussed and include defining the precise radio-anatomical position of the joint, standard criteria for X-ray beam alignment, allowance for inherent radiographic magnification and precise definition of anatomical boundaries. Protocols incorporating these criteria are described for standard radiography of the anteroposterior view of the tibiofemoral compartment in the standing semi-flexed position, and for the standing lateral and axial views of the patellofemoral joint. In these views, the radio-anatomical position of the joint is based upon the principal that there is only one plane in which the central ray of the X-ray beam will pass between the margins of the joint space so that both margins and space are optimally defined, in a position consistent with the functional loading of that joint.

Quantitative microfocal radiographic assessment of disease and progression in osteoarthritis of the hand.

Macroradiographic examination of the wrists and hands of 32 patients with osteoarthritis (OA) over an 18 month period showed that, compared with healthy control subjects, 44% of the patients had significant joint space narrowing at entry, which increased to 65%. Subchondral cortical thickness was greater in all patients at entry and increased with time. Osteophytes and juxtaarticular radiolucencies were present in all patients at study entry; by the end, osteophytes had increased in number and area, and juxtaarticular radiolucencies in area only. We conclude that in OA of the hand, bony changes have progressed significantly before joint space narrowing.