Assessing progression of patellofemoral osteoarthritis: a comparison between two radiographic methods

[Expert consensus on surgical treatment of patellofemoral osteoarthritis]

Patellofemoral osteoarthritis (PFOA) is one of the most common causes of anterior knee pain in middle-aged and elderly population. In general, elementary therapy and drug therapy are the preferred choices for PFOA management. However, for those who cannot achieve satisfactory effectiveness with standard non-surgical treatment, surgical therapy stands as an alternative treatment. The surgical therapy includes repair surgery and reconstruction surgery. The choice of surgical plans for PFOA management mainly depends on the etiology, pathogenesis, location, and severity of the lesions. To aid clinical decision-making, the National Clinical Research Center for Geriatric Disorders (Xiangya Hospital) and the Joint Surgery Branch of the Chinese Orthopedic Association arranged nationwide orthopedic specialists to set up a work panel. After reviewing the research progress of surgical therapy and the latest guidelines and consensus for PFOA management, the work panel discussed repeatedly to reach this consensus. The present consensus aims to provide valid evidences for clinical practices of the surgical therapy of PFOA, so as to avoid inappropriate and irregular treatment behaviors, reduce surgical trauma, improve surgical efficacy and the quality of life, and to ease the burden of PFOA.

The effects of knee meniscectomy on the development of osteoarthritis in the patellofemoral joint 40 years following meniscectomy

Most knee osteoarthritis and meniscectomy studies focus on osteoarthritis in the tibiofemoral joint and ignore the patellofemoral joint. This study aims to assess the long-term effects of total meniscectomy on the patellofemoral joint. To our knowledge, this is the only study of osteoarthritis in the patellofemoral joint following meniscectomy that extends to a 40-year follow-up period. Twenty-two patients with osteoarthritis were evaluated at a mean of 40 years post-meniscectomy using standardised weight-bearing radiographs of the operated and non-operated knees. Patellofemoral joint osteoarthritis was diagnosed by the presence of osteophytes and joint space narrowing to less than 5 mm. Kellgren and Lawrence scores were calculated from the radiographs. Patellofemoral joint osteoarthritis and tibiofemoral joint osteoarthritis were correlated with International Knee Documentation Committee scores and range of movement measurements. A significant difference was observed between the operated and non-operated knees in terms of patellofemoral joint osteophyte formation. There was a significant difference in tibiofemoral joint Kellgren and Lawrence scores, International Knee Documentation Committee scores and range of movement measurements between knees with lateral facet patellofemoral joint space of < 5 mm and > 5 mm. This study shows an association between open total meniscectomy and patellofemoral joint osteoarthritis at 40 years following surgery. There was also an association between patellofemoral joint space narrowing in the lateral facet and tibiofemoral joint osteoarthritis. Possible causes include altered biomechanical loading patterns following meniscectomy as well as global processes within the knee.

EULAR recommendations for the use of imaging in the clinical management of peripheral joint osteoarthritis

The increased information provided by modern imaging has led to its more extensive use. Our aim was to develop evidence-based recommendations for the use of imaging in the clinical management of the most common arthropathy, osteoarthritis (OA). A task force (including rheumatologists, radiologists, methodologists, primary care doctors and patients) from nine countries defined 10 questions on the role of imaging in OA to support a systematic literature review (SLR). Joints of interest were the knee, hip, hand and foot; imaging modalities included conventional radiography (CR), MRI, ultrasonography, CT and nuclear medicine. PubMed and EMBASE were searched. The evidence was presented to the task force who subsequently developed the recommendations. The strength of agreement for each recommendation was assessed. 17 011 references were identified from which 390 studies were included in the SLR. Seven recommendations were produced, covering the lack of need for diagnostic imaging in patients with typical symptoms; the role of imaging in differential diagnosis; the lack of benefit in monitoring when no therapeutic modification is related, though consideration is required when unexpected clinical deterioration occurs; CR as the first-choice imaging modality; consideration of how to correctly acquire images and the role of imaging in guiding local injections. Recommendations for future research were also developed based on gaps in evidence, such as the use of imaging in identifying therapeutic targets, and demonstrating the added value of imaging. These evidence-based recommendations and related research agenda provide the basis for sensible use of imaging in routine clinical assessment of people with OA.

Epidemiological characteristics of patellofemoral osteoarthritis in elderly Koreans and its symptomatic contribution in knee osteoarthritis

BACKGROUND

Many studies have reported the prevalence of knee osteoarthritis (OA) but have invariably focused on the tibiofemoral (TF) joint and overlooked the patellofemoral (PF) joint. Accordingly, little epidemiological information is available regarding the PF OA. The purpose of the current study was to document the epidemiological characteristics of PF OA in elderly Koreans.

METHODS

Radiographic assessment was performed for 681 elderly (≥65 years old) Koreans recruited from a community, and symptom severity was evaluated using Western Ontario and McMaster Universities Index (WOMAC) and Short Form-36 (SF-36) scales. Prevalence of different categories of knee OA (isolated PF OA, isolated TF OA and combined PF and TF OA) was calculated. The symptoms of isolated PF OA group and non-OA group were compared.

RESULTS

The overall prevalence of OA was 22.0% in the PF compartment and 34.1% in the TF compartment. The prevalence of isolated PF OA, isolated TF OA, and combined PF and TF OA was 3.8%, 17.8%, and 19.2%, respectively. Female sex, aging, and obesity were not associated with isolated PF OA. No significant differences were found in any clinical outcome scales between the isolated PF and non-OA groups.

CONCLUSION

This study documents that OA in the PF joint is common in elderly Koreans, but isolated PF OA is rare. Demographic risk factors are not associated with isolated PF OA, suggesting that isolated PF OA may have a different pathophysiology from other types of knee OA. Our study also indicates that the presence of isolated PF OA should not be construed to be responsible for clinical symptoms.

Sensitivity of standing radiographs to detect knee arthritis: a systematic review of Level I studies

PURPOSE

The purpose of this study was to perform a systematic review of the available literature to define the level of quality evidence for determining the sensitivity and specificity of different radiographic views in detecting knee osteoarthritis and to determine the impact of different grading systems on the ability to detect knee osteoarthritis.

METHODS

A systematic review of the literature was conducted to identify studies that evaluated the standing anteroposterior (AP) and 45° posteroanterior (PA) views for tibiofemoral and patellofemoral arthritis and those comparing the use of the Kellgren-Lawrence versus the joint space narrowing (JSN) radiographic grading systems using arthroscopy as the gold standard. A comprehensive search of PubMed, Scopus, CINAHL, the Cochrane Database, Clinicaltrial.gov, and EMBASE was performed using the keywords "osteoarthritis," "knee," "x-ray," "sensitivity," and "arthroscopy."

RESULTS

Six studies were included in the evaluation. The 45° flexion PA view showed a higher sensitivity than the standing AP view for detecting severe arthritis involving either the medial or lateral tibiofemoral compartment. There was no difference in the specificities for the 2 views. The direct comparison of the Kellgren-Lawrence and the JSN radiographic grading systems found no clinical difference between the 2 systems regarding the sensitivities, although the specificity was greater for the JSN system.

CONCLUSIONS

The ability to detect knee osteoarthritis continues to be difficult without using advanced imaging. However, as an inexpensive screening tool, the 45° flexion PA view is more sensitive than the standing AP view to detect severe tibiofemoral osteoarthritis. When evaluating the radiograph for severe osteoarthritis using either the Kellgren-Lawrence or JSN grading system, there is no clinical difference in the sensitivity between the 2 methods; however, the JSN may be more specific for ruling in severe osteoarthritis in the medial compartment.

LEVEL OF EVIDENCE

Level I, systematic review of Level I studies.

Minimum joint space width (mJSW) of patellofemoral joint on standing "skyline" radiographs: test-retest reproducibility and comparison with quantitative magnetic resonance imaging (qMRI)

OBJECTIVE

To assess the intraobserver, interobserver, and test-retest reproducibility of minimum joint space width (mJSW) measurement of medial and lateral patellofemoral joints on standing "skyline" radiographs and to compare the mJSW of the patellofemoral joint to the mean cartilage thickness calculated by quantitative magnetic resonance imaging (qMRI).

MATERIALS AND METHODS

A couple of standing "skyline" radiographs of the patellofemoral joints and MRI of 55 knees of 28 volunteers (18 females, ten males, mean age, 48.5 ± 16.2 years) were obtained on the same day. The mJSW of the patellofemoral joint was manually measured and Kellgren and Lawrence grade (KLG) was independently assessed by two observers. The mJSW was compared to the mean cartilage thickness of patellofemoral joint calculated by qMRI.

RESULTS

mJSW of the medial and lateral patellofemoral joint showed an excellent intraobserver agreement (interclass correlation (ICC) = 0.94 and 0.96), interobserver agreement (ICC = 0.90 and 0.95) and test-retest agreement (ICC = 0.92 and 0.96). The mJSW measured on radiographs was correlated to mean cartilage thickness calculated by qMRI (r = 0.71, p < 0.0001 for the medial PFJ and r = 0.81, p < 0.0001 for the lateral PFJ). However, there was a lack of concordance between radiographs and qMRI for extreme values of joint width and KLG. Radiographs yielded higher joint space measures than qMRI in knees with a normal joint space, while qMRI yielded higher joint space measures than radiographs in knees with joint space narrowing and higher KLG.

CONCLUSIONS

Standing "skyline" radiographs are a reproducible tool for measuring the mJSW of the patellofemoral joint. The mJSW of the patellofemoral joint on radiographs are correlated with, but not concordant with, qMRI measurements.

Radiologic assessment of patellofemoral pain in the athlete

CONTEXT

Although disorders of the patellofemoral joint are common in the athlete, their management can be challenging and require a thorough physical examination and radiologic evaluation, including advanced magnetic resonance imaging techniques.

EVIDENCE ACQUISITION

Relevant articles were searched under OVID and MEDLINE (1968 to 2010) using the keywords patellofemoral joint, patellofemoral pain or patella and radiography, imaging, or magnetic resonance imaging, and the referenced sources were reviewed for additional articles. The quality and validity of the studies were assessed on the basis of careful analysis of the materials and methods before their inclusion in this article.

RESULTS

Physical examination and imaging evaluation including standard radiographs are crucial in identifying evidence of malalignment or instability. Magnetic resonance imaging provides valuable information about concomitant soft tissue injuries to the medial stabilizers as well as injuries to the articular cartilage, including chondral shears and osteochondral fractures. Quantitative magnetic resonance imaging assessing the ultrastructure of cartilage has shown high correlation with histology and may be useful for timing surgery.

CONCLUSIONS

Evaluation of patellofemoral disorders is complex and requires a comprehensive assessment. Recent advancements in imaging have made possible a more precise evaluation of the individual anatomy of the patient, addressing issues of malalignment, instability, and underlying cartilage damage.

Short-term repeatability of joint space width measurements using a magnetic resonance imaging compatible knee positioning device

The purpose of this study was to evaluate a magnetic resonance imaging (MRI) compatible knee positioning device to aid in minimizing intratechnologist and intertechnologist differences of minimum joint space width (JSW) measurements. Five subjects were scanned by two separate technologists, with and without an MRI-compatible positioning device. A semi-automated program calculated the minimum JSW of the tibiofemoral and patellofemoral joints. The scan-to-scan repeatability was evaluated from measurements between serial scans without subject repositioning, and the intratechnologist and intertechnologist repeatabilities were evaluated when the subject was removed from the magnet and repositioned by an individual technologist. The root mean square (RMS) error of the JSW measurements was also calculated. All measures of scan-to-scan repeatability and intratechnologist repeatability were unchanged with the MRI-compatible positioning device. The intertechnologist repeatability decreased from 0.70 to 0.42 mm, and the RMS error was significantly reduced (P = 0.0006) from 0.26 to 0.15 mm for the tibiofemoral joint. The variability of patellofemoral JSW measurements increased when using the positioning device; however, the increases were not statistically significant. The intertechnologist repeatability increased from 1.55 to 1.79 mm, and the RMS error increased from 0.58 to 0.73 mm. The MRI-compatible positioning device was successful at reducing JSW measurement variability at the tibiofemoral joint. The increase in measurement variability at the patellofemoral joint may be due to local incongruities of the articular surfaces. An MRI-compatible positioning device may be beneficial for quantitative longitudinal studies evaluating knee joint health.

The patellar thinning osteotomy in patellofemoral arthritis: four to 18 years' follow-up

Isolated patellofemoral osteoarthritis can be a disabling disease. When conservative treatment fails, surgical options can be unpredictable and may be considered too aggressive for middle-aged and active people. We analysed the clinical and radiological results of a new coronal osteotomy involving thinning of the patella in a selected group of patients with isolated patellofemoral osteoarthritis. Since 1991, 31 patients (35 knees) have been treated, of whom 34 were available for follow-up at a mean of 9.1 years. The Knee Society Score, the Patellar score and the Short-form-36 questionnaire were used for clinical evaluation. We also examined the radiological features to confirm bone consolidation and assess the progression of osteoarthritis. A significant improvement in the functional scores and radiological parameters was noted. All patients except one were satisfied with the operation. Radiological progression of the patellofemoral osteoarthritis was slowed but radiological femorotibial osteoarthritis progressed in 23 (65%) cases, with a total knee replacement becoming necessary in four cases without technical problems in resurfacing the patella. We compared the results with other forms of surgical treatment reported in the literature. This treatment offers good clinical and radiological results, presenting an alternative method of managing patellofemoral osteoarthritis.

Evaluations of radiographic joint space--do they adequately predict cartilage conditions in the patellofemoral joint of the patients undergoing total knee arthroplasty for advanced knee osteoarthritis?

OBJECTIVE

To determine whether assessments of patellofemoral (PF) joint space reliably predict the cartilage conditions in the PF joint of the patients undergoing total knee arthroplasty (TKA) for advanced knee osteoarthritis.

METHODS

Radiographic joint spaces and gross cartilage conditions in the PF joint were assessed in 151 osteoarthritic knees undergoing TKA. Minimum joint space widths (MJSWs) in the medial and lateral compartments of the PF joint were measured separately on Merchant radiographs. Degrees of joint space were graded as normal, narrowed and obliterated, and expected locations of significant cartilage lesions were classified as medial, lateral, and global. Cartilage lesions were grossly assessed in terms of their severity (depth and size) and location. Cross-table analyses and kappa statistics were used to determine the level of agreements between radiographic and gross assessments and the diagnostic accuracies of the radiographic assessments.

RESULTS

The agreements between the radiographic assessments and the gross assessments on the lesion severities and locations were only fair [kappa coefficient (k)=0.288 and 0.211, respectively]. The cross-table analyses demonstrated that 45 (47.4%) of 95 knees with a normal radiographic joint space had moderate or severe cartilage degeneration of the PF joint identified with gross assessments. In the radiographic assessments, the lateral compartment of the PF joint was the most frequent location of joint space narrowing (71.4%) whereas in the gross assessments, the medial compartment of the PF joint was the most frequent location of significant cartilage lesion (48.1%). Diagnostic accuracies on the lesion severities and locations were generally poor.

CONCLUSION

This study demonstrates that prediction of the cartilage conditions of the PF joint by the radiographic joint space can be inaccurate.

Frontal plane knee alignment is associated with a longitudinal reduction in patella cartilage volume in people with knee osteoarthritis

OBJECTIVES

Varus-valgus alignment of the knee is increasingly becoming recognised as an important biomechanical variable in patellofemoral osteoarthritis (OA). The aim of this study was to determine the cross-sectional and longitudinal relationships between frontal plane knee alignment and patella cartilage volume in people with knee OA.

METHODS

Ninety-nine adults with symptomatic knee OA were recruited using a combined strategy including referral from specialist centres, arthritis support groups and media advertising. Both baseline and follow-up X-rays and magnetic resonance imaging (MRI) were performed 2 years apart. Knee alignment and patella cartilage volume were determined from X-ray and MRI, respectively.

RESULTS

Annual change in knee alignment was negatively associated with an annual change in the total patella cartilage volume before (P=0.002) and after (P=0.003) adjustment for potential confounders over an average of a 1.9-year period. For every 1 degrees change towards valgus direction, there was a 23.4-mm(3) [95% confidence interval (CI) 8.1 mm(3)-38.7 mm(3)] annual reduction in the total patella cartilage volume.

CONCLUSION

This study is the first to clearly demonstrate and quantitate the annual reduction in patella cartilage volume that occurs as knee alignment becomes increasingly valgus in an osteoarthritic cohort. Interventions that aim to minimise change towards valgus alignment may reduce the risk for the onset and progression of patellofemoral OA.

Partial lateral patellar facetectomy for treatment of arthritis due to lateral patellar compression syndrome

PURPOSE

The purpose of this study was to investigate the intermediate-term results of a retrospective clinical trial designed to establish the value of lateral retinaculum release of the patella in conjunction with partial lateral patella facetectomy in patients with stage III or stage IV patellofemoral arthritis.

METHODS

Between October 1992 and January 2005, all patients undergoing arthroscopy, lateral patellar retinaculum release, and lateral patella facetectomy were evaluated. In total, 66 knees in 63 patients (89%) were available for evaluation at a mean of 60 months after the index surgery. Evaluations consisted of preoperative and postoperative questionnaires, physical examinations, and radiographs. The main outcome measure was the Kujala patellofemoral score.

RESULTS

For those patients not undergoing total knee arthroplasty before evaluation, the mean Kujala score was 45.6 preoperatively and 72.0 postoperatively (P < .001); subjectively, 56% of patients were very satisfied, 32% satisfied and would repeat the procedure, 5% were indifferent, and 7% were dissatisfied and would not repeat the procedure. Including all patients who underwent total knee arthroplasty before evaluation and those who would not repeat the procedure or were indifferent, our accumulative failure rate was 17%. Correlations of several measures with the Kujala score, as well as subgroup comparisons of several measures between patients who were satisfied and those who were not satisfied with their reconstructions, were performed. However, all of these failed to achieve statistical significance after adjustment for multiple comparisons and so are not reported in this report.

CONCLUSIONS

Lateral patella retinaculum release and partial lateral patella facetectomy for end-stage patellofemoral disease provides up to 5 years of symptomatic relief in over 80% of carefully selected patients who do not have significant arthritis (grade IV) in the medial or lateral knee compartments. Significant lateral facet patellofemoral arthritis (grade IV) even in association with medial facet and femoral sulcus involvement is not a contraindication to this surgical approach.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

Femoral sulcus angle and increased patella facet cartilage volume in an osteoarthritic population

OBJECTIVE

The patellofemoral joint is an example of an incongruent articulation commonly affected by osteoarthritis (OA). The relationship between femoral sulcus angle and the development and progression of patellofemoral OA is unclear. The aim of this study was to examine the relationship between the femoral sulcus angle at baseline and patella cartilage volume at baseline and at 2-year follow-up among community based adults with established knee OA.

METHODS

One hundred subjects had magnetic resonance imaging of their symptomatic knee at baseline and at 2-year follow-up. From these images, patella cartilage volume was determined. Radiographic skyline views of the patellofemoral joint were taken at baseline to measure the femoral sulcus angle.

RESULTS

For every 1 degrees increase in the femoral sulcus angle (i.e., as the sulcus angle became more shallow) there was an associated 9.1mm3 (95% CI 3.1, 15.0) increase in medial patella cartilage volume at baseline (P=0.003). There was a similar trend that approached statistical significance between the femoral sulcus angle and the lateral patella facet cartilage volume at baseline (P=0.09). There was no association between the femoral sulcus angle at baseline and the change in patella cartilage volume over 2 years in either patellofemoral compartment.

CONCLUSION

These results infer that the femoral sulcus angle is a cross-sectional determinant of the amount of patella cartilage, but is not a major determinant of the annual change of patella cartilage volume among people with knee OA. These data suggest that a shallower sulcus in the context of established OA may be an advantageous anatomical variant. Further longitudinal studies are required to determine the role of the femoral sulcus angle in OA.

Prevalence, patterns, and risk factors of knee osteoarthritis in Thai monks

BACKGROUND

Patterns and risk factors of knee osteoarthritis in Asian countries where most people have habitual knee bending activities remain unclear. The objective of this study was to evaluate the prevalence, patterns, and risk factors of knee osteoarthritis in Thai monks.

METHODS

The study was a cross-sectional survey of monks who lived in temples in southern Thailand. Investigations included history, physical examination, and radiographic evaluation including weight-bearing antero-posterior, lateral, and skyline views.

RESULTS

There were 261 monks from 85 temples included in this study. The overall prevalence of radiographic knee osteoarthritis was 59.4%, with 29.6% having symptomatic radiographic knee osteoarthritis. The patterns of involvement were isolated tibiofemoral compartment (7.7%), isolated patellofemoral compartment (18.8%), and combined (32.9%). Obesity (OR 5.6, 95% CI; 1.6-19.8), age equal to or more than 60 years (OR 3.0, 95% CI; 1.5-6.0), and age at ordainment equal to or more than 46 years (OR 2.2, 95% CI; 1.1-4.6) were associated with risk of developing radiographic knee osteoarthritis. Obesity (OR 17.9, 95% CI; 2.4-132.1) and current smoking (OR 7.7, 95% CI; 2.4-24.3) were associated with symptomatic radiographic knee osteoarthritis. Severity of involvement was associated with obesity (OR 12.0, 95% CI; 2.3-60.9), older age (OR 3.8, 95% CI; 1.3-5.1), and older age at ordainment (OR 2.8, 95% CI; 1.3-6.1).

CONCLUSIONS

The prevalence of radiographic knee osteoarthritis with patellofemoral involvement in Thai monks is high and is more common among the elderly, those who were older at ordainment, and obese subgroups. Each pattern of knee osteoarthritis might have a different pathomechanism in the development of osteoarthritis.

The knee skyline radiograph: its usefulness in the diagnosis of patello-femoral osteoarthritis

The aim of this study was to determine the usefulness of the skyline radiograph in the diagnosis of patellofemoral osteoarthritis. Additionally, we wanted to assess the usefulness of patello-femoral crepitus as a clinical sign of this condition. Seventy-seven patients scheduled to undergo knee surgery had standard antero-posterior, lateral and skyline X-rays of their affected knee. The presence of clinical patello-femoral crepitus was also documented preoperatively. At the operation, their patellofemoral joints were graded into two groups according to the presence or absence of osteoarthritis. The lateral and skyline view X-rays as well as patello-femoral crepitus were compared individually against the operative findings. The skyline view had a sensitivity of 79% and a specificity of 80%. The lateral view had a sensitivity of 82% and specificity of 65%. Patello-femoral crepitus as a sign had a sensitivity of 89% and a specificity of 82%. There was no statistically significant difference between the two radiological views in terms of sensitivity and specificity in the diagnosis of patellofemoral osteoarthritis. Hence, we cannot recommend the skyline view as a routine radiological investigation in all cases of suspected patellofemoral osteoarthritis.

Semi-automated digital image analysis of patellofemoral joint space width from lateral knee radiographs

OBJECTIVE

To design a semi-automated program to measure minimum patellofemoral joint space width (JSW) using standing lateral view radiographs.

DESIGN

Lateral patellofemoral knee radiographs were obtained from 35 asymptomatic subjects. The radiographs were analyzed to report both the repeatability of the image analysis program and the reproducibility of JSW measurements within a 2 week period. The results were also compared with manual measurements done by an experienced musculoskeletal radiologist.

RESULTS

The image analysis program was shown to have an excellent coefficient of repeatability of 0.18 and 0.23 mm for intra- and inter-observer measurements respectively. The manual method measured a greater minimum JSW than the automated method. Reproducibility between days was comparable to other published results, but was less satisfactory for both manual and semi-automated measurements. The image analysis program had an inter-day coefficient of repeatability of 1.24 mm, which was lower than 1.66 mm for the manual method.

CONCLUSIONS

A repeatable semi-automated method for measurement of the patellofemoral JSW from radiographs has been developed. The method is more accurate than manual measurements. However, the between-day reproducibility is higher than the intra-day reproducibility. Further investigation of the protocol for obtaining sequential lateral knee radiographs is needed in order to reduce the between-day variability.

Does increasing the grades of the knee osteoarthritis line drawing atlas alter its clinimetric properties?

OBJECTIVES

To (a) develop further logically derived line drawing atlases (LDAs) for grading radiographic knee osteoarthritis (OA); and (b) determine which is superior using metrological criteria.

METHODS

A series of LDAs (-3 to +3, -4 to +4, and -5 to +5) were produced by (a) incorporating additional grades for osteophyte and joint space width (JSW) above the 0-3 pilot LDA, over an equivalent range of disease; and (b) adding negative grades for JSW. 121 sets of bilateral knee radiographs (standing, anteroposterior plus flexed skyline), plus serial views of 68 tibiofemoral joints (TFJs) and 36 patellofemoral joints were scored twice by one observer for each LDA. Minimum JSW of 50 radiograph sets was directly measured and awarded a categorical grade dependent upon the boundaries of each LDA grade. Time taken to grade 30 randomly selected knee radiograph sets was measured.

RESULTS

Intraobserver reproducibility was similar for all LDAs, (weighted kappa: JSW = 0.85-0.87; osteophyte = 0.77-0.79), with no deterioration with increasing grades. Criterion validity favoured the -5 to +5 LDA, which was also quickest to use. All atlases showed similar responsiveness (standardised response mean: medial TFJ JSW = 0.78-0.83; medial femoral osteophyte = 0.61-0.73), with most sites compromised by small sample size, little change in score, and high variation between subjects.

CONCLUSIONS

A set of LDAs was created illustrating the full range of normality/abnormality likely to be encountered in a community study of knee pain or OA. Despite superior validity and equivalent reproducibility, improved responsiveness of the -5 to +5 LDA was not confirmed.

Varus-valgus alignment in the progression of patellofemoral osteoarthritis

OBJECTIVE

To test the hypotheses that lateral patellofemoral (PF) osteoarthritis (OA) progression is more common than medial PF OA progression, that varus alignment increases the likelihood of medial PF OA progression, and that valgus alignment increases the likelihood of lateral PF OA progression.

METHODS

Patients with knee OA were recruited from the community. Inclusion criteria were definite osteophyte presence (i.e., Kellgren/Lawrence radiographic grade >/=2) in 1 or both knees and at least some difficulty with knee-requiring activity. Varus-valgus alignment (the angle formed by the intersection of the mechanical axes of the femur and tibia) was measured on a full-limb radiograph at baseline. To assess PF OA progression, weight-bearing skyline views of the PF compartment were obtained at baseline and at 18-month followup. Knees with the highest grade of PF narrowing at baseline were excluded from analysis. Logistic regression and generalized estimating equations were used; odds ratios (ORs) were adjusted for age, sex, and body mass index.

RESULTS

Lateral PF OA progression, which occurred in 120 (30%) of 397 knees, was more common than was medial PF OA progression, which occurred in 60 knees (15%). Varus (versus nonvarus) alignment increased the odds of PF OA progression isolated to the medial PF compartment (adjusted OR 1.85, 95% confidence interval [95% CI] 1.00-3.44). Valgus alignment increased the odds of PF OA progression isolated to the lateral compartment (adjusted OR 1.64, 95% CI 1.01-2.66).

CONCLUSION

Lateral PF OA progression was more common than medial progression, and varus-valgus alignment influenced the likelihood of PF OA progression in a compartment-specific manner. Interventions that address the stress imposed by alignment on the PF compartments may delay PF OA progression and should be developed.

Radiographic evaluation of osteoarthritis

Osteoarthritis is the most widespread form of arthritis in the United States. Classically, osteoarthritis has been grouped into primary and secondary types. Primary or idiopathic osteoarthritis is believed to be a sequela of altered biomechanical stresses across joints in susceptible individuals. Secondary osteoarthritis is a consequence of underlying cartilage damage, such as from preceding inflammatory arthritis, metabolic abnormality, or injury. The radiographic hallmark of osteoarthritis is asymmetric loss of cartilage space. Osteophytosis bony eburnation, subchondral cysts, and eventual subluxation follow. Osteoporosis and erosions are not usual features of this disease.

Distribution of MR-detected cartilage defects of the patellofemoral joint in chronic knee pain

OBJECTIVES

The aim of the study was to detect cartilage defects and determine the center of these defects in MR imaging of the patellofemoral joint (PFJ) in middle-aged people with chronic knee pain.

DESIGN

In the format of a prospective study of early osteoarthritis (OA), this cross-sectional study of the signal knee (the most painful one at inclusion in the study in 1990) in 59 individuals, 30 women and 29 men (aged 41-58 years, mean 50 years) with chronic knee pain, with or without radiographically determined knee OA, was examined using MR imaging on a 1.0 T imager. Cartilage defects and the center of these defects in the PFJ were recorded.

RESULTS

Cartilage defects were found more often in the patella (40 knees) than in the femoral trochlea (23 knees) (P<0.001) and were unevenly distributed in the patella (P<0.001), with most cartilage defects in the mid-patella.

CONCLUSIONS

Since cartilage defects occur more commonly in the mid-patella, radiographs obtained with a knee flexion of approximately 45 degrees may be more accurate to show cartilage defects of early OA of the PFJ than views with another knee flexion.

Joint space width of the tibiofemoral and of the patellofemoral joint in chronic knee pain with or without radiographic osteoarthritis: a 2-year follow-up

OBJECTIVES

To assess the interval change of the minimal joint space width (MJS) in radiographs of the tibiofemoral (TF) joint and of the patellofemoral (PF) joint with a 2-year follow-up in middle-aged people with longstanding knee pain with or without radiographic osteoarthritis (OA) and to study the precision of the MJS measurements.

DESIGN

In the format of a prospective study of early OA the signal knee in 55 people, 28 men and 27 women (aged 41-57 years, median 50), with chronic knee pain at inclusion was examined with a 2-year interval (median 25 months, range 21-30). The MJS of the TF joint was measured using a flexed PA view in weightbearing and the MJS of the PF joint using an axial view in standing.

RESULTS

The MJS of the TF joint decreased medially by 0.056+/-0.44mm (n.s.) and increased laterally by 0.080+/-0.51mm (n.s.) during the time of observation. In knees with an MJS medially that was less or the same as compared with the lateral compartment, the MJS decreased by 0.14+/-0.38mm (p=0.038) and in a subgroup of these knees, without osteophytes, the MJS decreased by 0.14+/-0.27mm (p=0.018). The MJS of the PF joint decreased by 0.019mm (n.s.) during the time of observation. The coefficient of variation for intra- and interobserver MJS measurements of the TF joint was 1.0 and 1.1% medially and 2.3 and 2.7% laterally, and for measurement error 6.9% medially and 4.8% laterally, respectively. The coefficient of variation for intra- and interobserver MJS measurements of the PF joint was 8.1 and 5.8% medially and 7.5 and 10.1% laterally and for the measurement error it was 8.1% medially and 8.5% laterally, respectively.

CONCLUSIONS

A statistically significant reduction of the MJS was only demonstrated in the medial compartment of the TF joint in those individuals who had an MJS in this compartment which was less or the same as compared with the lateral compartment as well as in a subgroup of these knees without osteophytes. The radiographic examinations and the MJS measurements were reproducible.

The radiologic prevalence of patellofemoral osteoarthritis

The radiographs of 206 knees from 174 consecutive patients were reported blinded regarding joint space narrowing. Minimum joint space was measured using a millimeter ruler on weightbearing posteroanterior and skyline patellofemoral radiographs. Lateral radiographs were reported solely in terms of presence or absence of patellofemoral arthritis. The results showed objective joint space narrowing to less than 3 mm in the patellofemoral compartment of 32.7% of men and 36.1% of women older than 60 years. This high prevalence of patellofemoral disease in men has not been documented before. Arthritic changes occurred in the patellofemoral compartment in isolation in 13.6% of women and 15.4% of men older than 60 years. The lateral radiograph had poor results for detection of patellofemoral osteoarthritis with a sensitivity of 66% and specificity of 83%. The positive predictive value of an abnormal lateral radiograph was 52%. If requests for skyline radiographs had been confined to patients with abnormal patellofemoral joints as assessed on lateral films then 28 normal joints would have been imaged and 14 abnormal joints would have been missed. Osteoarthritis is more common in the patellofemoral joints of men and women than previously documented and only can be properly assessed using a skyline radiograph.

Development of a logically devised line drawing atlas for grading of knee osteoarthritis

OBJECTIVES

To (a) develop an atlas of line drawings for the assessment and grading of narrowing and osteophyte (that is, changes of osteoarthritis) on knee radiographs, and (b) compare the performance of this atlas with that of the standard Osteoarthritis Research Society (OARS) photographic atlas of radiographs.

METHODS

Normal joint space widths (grade 0) for the medial and lateral tibiofemoral and medial and lateral patellofemoral compartments were obtained from a previous community study. Grades 1-3 narrowing in each compartment was calculated separately for men and women, grade 3 being bone on bone, grades 1 and 2 being two thirds and one third the value of grade 0. Maximum osteophyte size (grade 3) for each of eight sites was determined from 715 bilateral knee x ray films obtained in a knee osteoarthritis (OA) hospital clinic; grades 1-2 were calculated as two thirds and one third reductions in the area of grade 3. Drawings for narrowing and osteophyte were presented separately. 50 sets of bilateral knee x ray radiographs (standing, extended anteroposterior; flexed skyline) showing a spectrum of OA grades were scored by three observers, twice using the OARS atlas and twice using the drawn atlas.

RESULTS

Intraobserver and interobserver reproducibility was similar and generally good with both atlases, though varied according to site. All three observers preferred the line drawing atlas for ease and convenience of use. Higher scores for patellofemoral narrowing and lower scores for osteophyte, especially medial femoral osteophyte, were seen using the line drawing atlas, showing that the two atlases are not equivalent instruments.

CONCLUSION

A logically derived line drawing atlas for grading of narrowing and osteophyte at the knee has been produced. The atlas showed comparable reproducibility with the OARS atlas, but was discordant in several aspects of grading. Such a system has several theoretical and practical advantages and should be considered for use in knee OA studies.

Radiographic assessment of symptomatic knee osteoarthritis in the community: definitions and normal joint space

OBJECTIVE

To evaluate radiographic features of osteoarthritis (OA) to determine which is more closely associated with knee pain and hence might be used as a radiographic definition of OA in the community. To evaluate joint space width in normal subjects.

METHODS

452 subjects from a case-control community study of knee pain (294 women, 158 men, mean age 62 years, range 40-80) underwent AP standing and midflexion skyline radiographs. Joint space width, measured by metered calliper to 0.1 mm, and graded individual features of OA (osteophyte 0-3, narrowing 0-3, sclerosis 0-1, cysts 0-1) were assessed in all three compartments independently by two observers who were blind to clinical status. Subjects were categorised as having knee pain by a positive response to both parts of the question "Have you ever had pain in or around the knee on most days for at least a month? If so, have you experienced any pain during the last year?"

RESULTS

Intraobserver reproducibility for joint space width measurements was to within +/- 0.4 mm (95% CI for limits of agreement); kappa values for grading were > 0.7. One hundred and twenty five subjects were without knee pain or osteophyte. In these radiographically normal knees, mean joint space width varied according to sex but did not decrease with age. A definition based on the presence of osteophyte > or = grade 1 in any compartment was more efficient at predicting pain than definitions based on either measurement or grading of joint space; there was no clear threshold of joint space loss at which the likelihood of pain substantially increased. The presence of osteophyte at the patellofemoral joint (PFJ) was more sensitive but less specific than at the tibiofemoral joint (TFJ); the addition of PFJ assessment improved sensitivity from 38.1% to 62.3% with a reduction in specificity from 82.7% to 58.7% for the presence of knee pain.

CONCLUSION

Among men and women in the community, osteophyte is the radiographic feature that associates best with knee pain. Radiographic assessment of both TFJ and PFJ should be included in all community studies. Joint space loss is not a feature of asymptomatic aging, and there is not a biological cut off for joint space width below which the likelihood of knee pain markedly increases.

Correlation between radiographically diagnosed osteophytes and magnetic resonance detected cartilage defects in the patellofemoral joint

OBJECTIVE

To assess the correlation between radiographically diagnosed osteophytes in the axial and lateral view of the patellofemoral joint (PFJ) and (1) magnetic resonance (MR) detected cartilage defects in the same joint and (2) knee pain.

METHODS

Fifty-seven people with chronic knee pain, (aged 41-58 years, mean 50 years) were examined with axial and lateral radiograms when standing of the right and the left PFJ. The presence and grade of osteophytes was assessed. On the same day, a MR examination was performed of the signal knee with proton density and T2 weighted turbo spin-echo sequences in the sagittal and axial view on a 1.0 T imager. Cartilage defects in the PFJ were noted. The subjects were questioned for current knee pain for each knee.

RESULTS

Osteophytes at the PFJ had a specificity varying between 59 and 100% and a positive predictive value between 74 and 100% for MR detected cartilage defects. The corresponding values for osteophytes at the lateral aspect of the femoral trochlea were both 100%. In PFJ with narrowing (< 5 mm) osteophytes had a sensitivity and a positive predictive value of 90 and 95% respectively for MR detected cartilage defects, while in PFJ with non-narrowing (> or = 5 mm) the corresponding values were 75 and 65% and the specificity was 50%. A correlation (p < 0.05) between osteophytes at the inferior pole of the patella and knee pain was found.

CONCLUSIONS

Osteophytes at the PFJ are associated with MR detected cartilage defects in the same joint. The relation was strong for osteophytes at the lateral femoral trochlea and in the PFJ with narrowing (< 5 mm), but weak in the PFJ with non-narrowing (> or = 5 mm).