Knee osteoarthritis risk in non-industrial societies undergoing an energy balance transition: evidence from the indigenous Tarahumara of Mexico.

Non-industrial societies with low energy balance levels are expected to be less vulnerable than industrial societies to diseases associated with obesity including knee osteoarthritis. However, as non-industrial societies undergo rapid lifestyle changes that promote positive energy balance, individuals whose metabolisms are adapted to energetic scarcity are encountering greater energy abundance, increasing their propensity to accumulate abdominal adipose tissue and thus potentially their sensitivity to obesity-related diseases. OBJECTIVES: Here, we propose that knee osteoarthritis is one such disease for which susceptibility is amplified by this energy balance transition. METHODS: Support for our hypothesis comes from comparisons of knee radiographs, knee pain and anthropometry among men aged ≥40 years in two populations: Tarahumara subsistence farmers in Mexico undergoing the energy balance transition and urban Americans from Framingham, Massachusetts. RESULTS: We show that despite having markedly lower obesity levels than the Americans, the Tarahumara appear predisposed to accrue greater abdominal adiposity (ie, larger abdomens) for a given body weight, and are more vulnerable to radiographic and symptomatic knee osteoarthritis at lower levels of body mass index. Also, proportionate increases in abdomen size in the two groups are associated with greater increases in radiographic knee osteoarthritis risk among the Tarahumara than the Americans, implying that the abdominal adipose tissue of the Tarahumara is a more potent stimulus for knee degeneration. CONCLUSIONS: Heightened vulnerability to knee osteoarthritis among non-industrial societies experiencing rapid lifestyle changes is a concern that warrants further investigation since such groups represent a large but understudied fraction of the global population.

Meniscal body extrusion and cartilage coverage in middle-aged and elderly without radiographic knee osteoarthritis.

OBJECTIVES: To determine meniscal extrusion and cartilage coverage on magnetic resonance (MR) images and factors associated with these parameters in knees of middle-aged and elderly persons free from radiographic tibiofemoral osteoarthritis (OA). METHODS: Seven hundred eighteen persons, free of radiographic tibiofemoral OA, aged 50-90 years from Framingham, MA, USA, were included. We measured meniscal extrusion on 1.5 T MRI of both knees to evaluate both medial and lateral meniscal body extrusion and cartilage coverage. We also determined meniscal morphology and structural integrity. The multivariable association with age, body mass index (BMI), and ipsilateral meniscal damage was also evaluated. RESULTS: The mean meniscal body extrusion medially was 2.7 mm and laterally 1.8 mm. The tibial cartilage coverage was about 30% of ipsilateral cartilage surface (both compartments). The presence of ipsilateral meniscal damage was associated with more extrusion in only the medial compartment, 1.0 mm in men and 0.6 mm in women, and less cartilage coverage proportion, -5.5% in men and -4.6% in women. CONCLUSIONS: Mean medial meniscal body extrusion in middle-aged or older persons without radiographic tibiofemoral OA approximates the commonly used cutoff (3 mm) to denote pathological extrusion. Medial meniscal damage is a factor associated with medial meniscal body extrusion and less cartilage coverage. KEY POINTS: • Medial meniscal extrusion in middle-aged/older persons without OA is around 3 mm. • Lateral meniscal extrusion in middle-aged/older persons without OA is around 2 mm. • Meniscal damage is associated with medial meniscal extrusion and less cartilage coverage.

Metabolic Syndrome, Its Components, and Knee Osteoarthritis: The Framingham Osteoarthritis Study.

OBJECTIVE: Previous studies have suggested that metabolic syndrome is associated with osteoarthritis (OA). However, analyses have often not included adjustment for body mass index (BMI) and have not addressed whether levels of individual metabolic syndrome components are related to OA. This study was undertaken to examine the relationship of metabolic syndrome and its components with radiographic and symptomatic knee OA. METHODS: Framingham Study subjects were assessed for OA in 1992-1995 and again in 2002-2005. Near the baseline visit, subjects had components of metabolic syndrome assessed. We defined incident radiographic OA as present when a knee without radiographic OA at baseline had a Kellgren/Lawrence grade of ≥2 at follow-up, and defined incident symptomatic OA as present when a knee developed the new combination of radiographic OA and knee pain. After excluding knees with prevalent OA at baseline, we tested the relationship of metabolic syndrome according to the National Cholesterol Education Program Adult Treatment Panel III criteria and its components with the risk of incident radiographic OA and symptomatic OA before and after adjusting for BMI using the risk ratio from a binary regression with generalized estimating equations. RESULTS: A total of 991 subjects (55.1% women) with a mean age of 54.2 years were studied, and 26.7% of men and 22.9% of women had metabolic syndrome. Metabolic syndrome and many of its components were associated with both incident radiographic OA and symptomatic OA, but after adjustment for BMI, almost all of these associations became weak and nonsignificant. An association of high blood pressure, especially diastolic pressure, with OA outcomes persisted in both men and women. CONCLUSION: After adjustment for BMI, neither metabolic syndrome nor its components were associated with incident OA. There may be an association between OA and high blood pressure that needs further study.

Osseous sarcoidosis: clinical characteristics, treatment, and outcomes--experience from a large, academic hospital.

OBJECTIVE: Osseous sarcoidosis has been infrequently reported. We aimed to characterize the distribution of lesions, clinical presentation, treatment, and outcomes for osseous sarcoidosis. METHODS: Cases of osseous sarcoidosis were identified by directed inquiry to clinicians and electronic query. Cases were defined as having pathologic evidence of non-caseating granulomas on bone biopsy or evidence of osseous lesions on imaging attributable to sarcoidosis in patients with known sarcoidosis. Detailed characteristics were obtained by medical record review. RESULTS: We identified a total of 20 cases of osseous sarcoidosis. Osseous lesions were detected by imaging during the initial sarcoidosis presentation in 60% of cases. In those who had a prior diagnosis of sarcoidosis, the median duration of sarcoidosis before detection of osseous involvement was 4.3 years. Symptoms were present in 50% of cases. All cases had more than one bone involved. The axial skeleton was involved in the majority of cases (90%), primarily the pelvis and the lumbar spine. Most cases required no treatment (55%); a minority of cases (45%) were treated, most often with prednisone, methotrexate, or hydroxychloroquine. Two cases required multiple immunosuppressants, including tumor necrosis factor inhibitors, for refractory symptomatic osseous sarcoidosis. Treated cases were younger than those who were untreated. At last follow-up, most cases (85%) were asymptomatic from osseous lesions. CONCLUSIONS: In this case series of osseous sarcoidosis from a single center, most patients had multiple bones affected and had other systemic manifestations of sarcoidosis. A minority required treatment for relief of symptoms, and most cases were asymptomatic at last follow-up.

Progression of osteoarthritis as a state of inertia.

OBJECTIVES: To test whether knees which recently developed disease were at higher risk for subsequent x-ray progression than knees which had been stable, suggesting that recent change produces further change and recent stability yields subsequent stability (a pattern of inertia). METHODS: We used central readings of the annual posteroanterior x-rays obtained in the Osteoarthritis Initiative (OAI) focusing on change in Kellgren and Lawrence (KL) grade and change in semiquantitative joint space. We examined whether knees that had developed incident disease (KL grade 2) were at higher risk of subsequent progression than knees that were already grade 2 and had had stable disease. We combined data from multiple examinations. Using generalised estimating equations to adjust for the correlation between knees, we carried out logistic regression evaluating the risk for disease progression testing incident versus stable disease adjusting for age, sex, body mass index, physical activity, quadriceps strength and mechanical alignment. RESULTS: 1562 OAI subjects with grade 2 disease had a mean age of 61.8 years, mean BMI of 29.4, and 61.7% were women. Of knees with stable disease, 4.1% showed progression within the next 12 months in KL grade versus 13.7% in those with incident disease (adjusted OR 4.0; 95% CI 2.4 to 6.7). For progression of joint space loss, we found a similar relation with incident versus stable disease (adjusted OR 5.3; 95% CI 3.6 to 7.9). CONCLUSIONS: Knee osteoarthritis radiographic progression follows a pattern of inertia. Factors that trigger the transition from stable disease to progression should be sought.

Prevalence of abnormalities in knees detected by MRI in adults without knee osteoarthritis: population based observational study (Framingham Osteoarthritis Study).

OBJECTIVE: To examine use of magnetic resonance imaging (MRI) of knees with no radiographic evidence of osteoarthritis to determine the prevalence of structural lesions associated with osteoarthritis and their relation to age, sex, and obesity. DESIGN: Population based observational study. SETTING: Community cohort in Framingham, MA, United States (Framingham osteoarthritis study). PARTICIPANTS: 710 people aged >50 who had no radiographic evidence of knee osteoarthritis (Kellgren-Lawrence grade 0) and who underwent MRI of the knee. MAIN OUTCOME MEASURES: Prevalence of MRI findings that are suggestive of knee osteoarthritis (osteophytes, cartilage damage, bone marrow lesions, subchondral cysts, meniscal lesions, synovitis, attrition, and ligamentous lesions) in all participants and after stratification by age, sex, body mass index (BMI), and the presence or absence of knee pain. Pain was assessed by three different questions and also by WOMAC questionnaire. RESULTS: Of the 710 participants, 393 (55%) were women, 660 (93%) were white, and 206 (29%) had knee pain in the past month. The mean age was 62.3 years and mean BMI was 27.9. Prevalence of "any abnormality" was 89% (631/710) overall. Osteophytes were the most common abnormality among all participants (74%, 524/710), followed by cartilage damage (69%, 492/710) and bone marrow lesions (52%, 371/710). The higher the age, the higher the prevalence of all types of abnormalities detectable by MRI. There were no significant differences in the prevalence of any of the features between BMI groups. The prevalence of at least one type of pathology ("any abnormality") was high in both painful (90-97%, depending on pain definition) and painless (86-88%) knees. CONCLUSIONS: MRI shows lesions in the tibiofemoral joint in most middle aged and elderly people in whom knee radiographs do not show any features of osteoarthritis, regardless of pain.

The association between erosive hand osteoarthritis and subchondral bone attrition of the knee: the Framingham Osteoarthritis Study.

OBJECTIVE: To examine whether erosive hand osteoarthritis (OA) is associated with knee subchondral bone attrition (SBA) and systemic bone mineral density (BMD). METHODS: Associations of MRI-defined knee SBA with radiographic erosive hand OA were evaluated in 1253 Framingham participants using logistic regression with generalised estimating equations. We also examined the association between the number of erosive OA finger joints and SBA adjusted for the number of non-erosive OA finger joints. Associations between erosive hand OA and femoral neck BMD were explored in 2236 participants with linear regression. Analyses were adjusted for age, sex and body mass index. RESULTS: Participants with erosive hand OA had increased odds of knee SBA (OR=1.60, 95% CI 1.07 to 2.38). The relation between the number of erosive OA finger joints and SBA became non-significant when adjusted for the number of non-erosive OA joints as a proxy for the burden of disease. There was a non-significant trend towards higher BMD in erosive hand OA compared with participants without hand OA. CONCLUSIONS: Erosive hand OA was associated with knee SBA, but the relation might be best explained by a heightened burden of disease. No significant relation of erosive hand OA with BMD was found.

Relation of hand enthesophytes with knee enthesopathy: is osteoarthritis related to a systemic enthesopathy?

OBJECTIVE: Enthesopathy has been reported as a feature of osteoarthritis (OA) in the distal interphalangeal (DIP) joints. We previously reported that central bone marrow lesions (BML) on magnetic resonance imaging (MRI) scans are associated with OA. In this study, we evaluated whether hand and knee enthesopathy were related. METHODS: We studied knee and hand radiographs of subjects from the Framingham Osteoarthritis Study. Subjects seen in 2002-2005 had bilateral posteroanterior hand radiographs, weight-bearing knee radiographs, and knee MRI scans. Hand radiographs were read for enthesophytes at the juxtaarticular nonsynovial areas of metacarpophalangeal (MCP), proximal interphalangeal (PIP), and DIP joints, and midshafts of the phalanges. We selected 100 cases of knees with central BML and 100 matched controls. Conditional logistic regression was used to assess associations. RESULTS: Subjects with enthesophytes of at least 1 score ≥ 2 at DIP, PIP, and/or MCP were not more likely to have central knee BML (OR 0.49, 95% CI 0.17-1.40) than those without enthesophytes. Similarly, having at least 1 score ≥ 2 on the shafts was not significantly associated with having a central knee BML (OR 0.59, 95% CI 0.23-1.51). Adjustment for the presence of diabetes mellitus did not affect these results, but there was an increased prevalence of diabetes in those with hand enthesophytes (OR 3.09, 95% 1.29-7.40, enthesophyte score ≥ 2). CONCLUSION: We found no increase in the prevalence of hand enthesophytes among persons with central knee BML on their knee MRI scans. This provides evidence against a systemic enthesopathic disorder in association with knee OA.

Prevalence, incidence and progression of hand osteoarthritis in the general population: the Framingham Osteoarthritis Study.

OBJECTIVES: To describe the prevalence and longitudinal course of radiographic, erosive and symptomatic hand osteoarthritis (HOA) in the general population. METHODS: Framingham osteoarthritis (OA) study participants obtained bilateral hand radiographs at baseline and 9-year follow-up. The authors defined radiographic HOA at joint level as Kellgren-Lawrence grade (KLG)≥2, erosive HOA as KLG≥2 plus erosion and symptomatic HOA as KLG≥2 plus pain/aching/stiffness. Presence of HOA at individual level was defined as ≥1 affected joint. The prevalence was age-standardised (US 2000 Population 40-84 years). RESULTS: Mean (SD) baseline age was 58.9 (9.9) years (56.5% women). The age-standardised prevalence of HOA was only modestly higher in women (44.2%) than men (37.7%), whereas the age-standardised prevalence of erosive and symptomatic OA was much higher in women (9.9% vs 3.3%, and 15.9% vs 8.2%). The crude incidence of HOA over 9-year follow-up was similar in women (34.6%) and men (33.7%), whereas the majority of those women (96.4%) and men (91.4%) with HOA at baseline showed progression during follow-up. Incident metacarpophalangeal and wrist OA were rare, but occurred more frequently and from an earlier age in men than women. Development of erosive disease occurred mainly in those with non-erosive HOA at baseline (as opposed to those without HOA), and was more frequent in women (17.3%) than men (9.6%). CONCLUSIONS: The usual female predominance of prevalent and incident HOA was less clear for radiographic HOA than for symptomatic and erosive HOA. With an ageing population, the impact of HOA will further increase.

No association between markers of inflammation and osteoarthritis of the hands and knees.

OBJECTIVE: Local inflammation plays a prominent role in osteoarthritis (OA). This could be reflected in the presence of elevated soluble inflammatory markers. We conducted analyses to assess the association of inflammatory markers with radiographic OA of the hands and knees in a large community-based cohort. METHODS: The Framingham Offspring cohort consists of the adult children of the original cohort and their spouses. In 1998-2001 these subjects provided blood specimens that were tested for 17 markers of systemic inflammation. In 2002-2005 these subjects had radiographs of both knees and hands. Each hand and knee joint was assigned a Kellgren and Lawrence (KL) score (0-4). We used logistic regression with generalized estimating equations and adjustment for age, sex, and body mass index to examine the association between each inflammatory marker and the presence of radiographic OA (ROA = KL grade ≥ 2) in any joint. We also constructed models for hand joints and knee joints alone. RESULTS: Radiographs and measures of inflammation were done for 1235 subjects (56% women, mean age 65 yrs). Of that group, 729 subjects (59%) had ROA in ≥ 1 hand or knee joint: 179 (14.3%) had knee OA, and 694 (56.2%) had hand OA. There were no significant associations between any marker of inflammation and ROA. CONCLUSION: In this large sample, in which OA was carefully assessed and multiple markers measured, we found no evidence of an association between any inflammatory marker and the presence of radiographic OA.

The associations between finger length pattern, osteoarthritis, and knee injury: data from the Framingham community cohort.

OBJECTIVE: To investigate the associations of index finger-to-ring finger (2D:4D) length ratio with radiographic knee and hand osteoarthritis (OA), previous knee injury, and meniscal lesions in the general population. METHODS: We measured the length of the right second and fourth phalangeal and metacarpal bones on hand radiographs from 1,020 randomly recruited subjects (ages 51-92 years). Knee radiography and magnetic resonance imaging (MRI) were performed on subjects. Women and men were divided into tertiles according to their 2D:4D phalangeal and metacarpal ratios. We assessed the odds ratios (ORs) and 95% confidence intervals (95% CIs) for radiographic knee OA, severe symptomatic knee OA, radiographic hand OA, previous knee injury, and MRI-defined meniscal lesion, using logistic regression with adjustment for age and body mass index. Because hand OA may affect the 2D:4D phalangeal ratio, we performed sensitivity analyses in subjects without joint space narrowing in the second and fourth interphalangeal joints. RESULTS: We found no significant associations between 2D:4D length ratio and radiographic knee OA, severe symptomatic knee OA, or meniscal lesions. Low 2D:4D phalangeal ratio was associated with hand OA in women (OR 1.80, 95% CI 1.11-2.93), but in the sensitivity analysis, the association was attenuated (OR 1.35, 95% CI 0.79-2.32). Low 2D:4D phalangeal ratios were associated with knee injury in men (OR 1.78, 95% CI 1.02-3.10). We found no significant associations for 2D:4D metacarpal ratios. CONCLUSION: Low 2D:4D phalangeal ratios in men are associated with knee injury, but we did not find any significant association with knee OA. Low 2D:4D length ratio may be a consequence, rather than a cause, of hand OA in women.

The relationship of estrogen receptor-alpha and -beta genes with osteoarthritis of the hand.

OBJECTIVE: We examined reported associations between radiographic hand osteoarthritis (OA) and single-nucleotide polymorphisms (SNP) in 2 candidate genes associated with OA in other joints: estrogen receptor alpha (ESR1) and beta (ESR2). METHODS: In 539 Framingham Offspring Study participants (49% men; mean age 61 +/- 9 yrs) joint-specific radiographic hand OA was defined as Kellgren/Lawrence (K/L) scores >or= 2 in the first carpometacarpal joint (CMC), distal interphalangeal joints (DIP), first-digit interphalangeal joint (IP), or proximal interphalangeal joints (PIP). Four SNP were genotyped for ESR1 (PvuII-rs2234693, XbaI-rs9340799, rs2077647, and rs1801132) and 4 for ESR2 (rs1256031, rs1256034, rs1256059, rs944460). Logistic regression analyses were performed to evaluate the relationships between genotypes and hand OA, adjusting for age, sex, height, and weight. RESULTS: Radiographic hand OA was identified in at least one investigated joint of DIP (39%), PIP (33%), and first CMC (40%). There was no evidence of association between OA and genotype at any polymorphism. We found no significant association between our OA phenotypes or generalized or severe generalized OA as defined by Ushiyama and heterozygosity for rs2234693 and rs9340799, although in metaanalysis with the former study this heterozygosity remained significantly associated with generalized or severe generalized OA. CONCLUSION: We found no significant association between hand OA and the investigated polymorphisms of ESR1 or ESR2 despite published reports of association and a priori hypotheses implicating their potential roles. However, we could not absolutely exclude associations with rs2234693, rs9340799, or rs944460.

Accuracy of cross-table lateral knee radiography for evaluation of joint effusions.

OBJECTIVE: The purpose of our study was to investigate the efficacy of cross-table lateral knee radiography in the diagnosis of knee effusions compared with an MRI reference standard, to evaluate reader experience in effusion assessment, and to establish a new threshold for suprapatellar pouch measurement for the diagnosis of effusion. MATERIALS AND METHODS: First- and third-year radiology residents and an attending musculoskeletal radiologist retrospectively assessed 108 cross-table lateral knee radiographs for qualitative grading of joint fluid and quantitative measurement of the suprapatellar pouch. Qualitative and quantitative evaluation of ipsilateral knee MRI examinations performed within 1 week of radiography was performed by two attending musculoskeletal radiologists as a reference standard. RESULTS: Qualitative visual grading of cross-table lateral radiographs had a sensitivity of 90-92%, specificity of 39-54%, and accuracy of 69-76% for joint effusion. Extrapolating from previous work showing 4 mL of fluid distends the suprapatellar pouch to 4 mm on midline sagittal MRI, the corresponding measurement on cross-table lateral radiographs was predicted to be 7 mm. Using this new criterion of effusion, sensitivity, specificity, and accuracy compared with an MR midline sagittal reference standard were 76%, 83%, and 81%, respectively. Historical data for overhead lateral radiographs had a sensitivity of 78%, specificity of 80%, and accuracy of 79%. CONCLUSION: Qualitative visual assessment of cross-table lateral knee radiographs is highly sensitive for the detection of joint effusion. By performing quantitative evaluation with a new 7-mm criterion for suprapatellar pouch measurement, sensitivity, specificity, and accuracy are equivalent to that of overhead lateral radiography.

Association between radiographic features of knee osteoarthritis and pain: results from two cohort studies.

OBJECTIVE: To examine the relation of radiographic features of osteoarthritis to knee pain in people with knees discordant for knee pain in two cohorts. DESIGN: Within person, knee matched, case-control study. SETTING AND PARTICIPANTS: Participants in the Multicenter Osteoarthritis (MOST) and Framingham Osteoarthritis studies who had knee radiographs and assessments of knee pain. MAIN OUTCOME MEASURES: Association of each pain measure (frequency, consistency, and severity) with radiographic osteoarthritis, as assessed by Kellgren and Lawrence grade (0-4) and osteophyte and joint space narrowing grades (0-3) among matched sets of two knees within individual participants whose knees were discordant for pain status. RESULTS: 696 people from MOST and 336 people from Framingham were included. Kellgren and Lawrence grades were strongly associated with frequent knee pain-for example, for Kellgren and Lawrence grade 4 v grade 0 the odds ratio for pain was 151 (95% confidence interval 43 to 526) in MOST and 73 (16 to 331) in Framingham (both P<0.001 for trend). Similar results were also seen for the relation of Kellgren and Lawrence scores to consistency and severity of knee pain. Joint space narrowing was more strongly associated with each pain measure than were osteophytes. CONCLUSIONS: Using a method that minimises between person confounding, this study found that radiographic osteoarthritis and individual radiographic features of osteoarthritis were strongly associated with knee pain.

Meniscal tear in knees without surgery and the development of radiographic osteoarthritis among middle-aged and elderly persons: The Multicenter Osteoarthritis Study.

OBJECTIVE: Although partial meniscectomy is a risk factor for the development of knee osteoarthritis (OA), there is a lack of evidence that meniscal damage that is not treated with surgery would also lead to OA, suggesting that surgery itself may cause joint damage. Furthermore, meniscal damage is common. The aim of this study was to evaluate the association between meniscal damage in knees without surgery and the development of radiographic tibiofemoral OA. METHODS: We conducted a prospective case-control study nested within the observational Multicenter Osteoarthritis Study, which included a sample of men and women ages 50-79 years at high risk of knee OA who were recruited from the community. Patients who had no baseline radiographic knee OA but in whom tibiofemoral OA developed during the 30-month followup period were cases (n = 121). Control subjects (n = 294) were drawn randomly from the same source population as cases but had no knee OA after 30 months of followup. Individuals whose knees had previously undergone surgery were excluded. Meniscal damage was defined as the presence of any medial or lateral meniscal tearing, maceration, or destruction. RESULTS: Meniscal damage at baseline was more common in case knees than in control knees (54% versus 18%; P < 0.001). The model comparing any meniscal damage with no meniscal damage (adjusted for baseline age, sex, body mass index, physical activity, and mechanical knee alignment) yielded an odds ratio of 5.7 (95% confidence interval 3.4-9.4). CONCLUSION: In knees without surgery, meniscal damage is a potent risk factor for the development of radiographic OA. These results highlight the need for better understanding, prevention, and treatment of meniscal damage.

Incidental meniscal findings on knee MRI in middle-aged and elderly persons.

BACKGROUND: Magnetic resonance imaging (MRI) of the knee is often performed in patients who have knee symptoms of unclear cause. When meniscal tears are found, it is commonly assumed that the symptoms are attributable to them. However, there is a paucity of data regarding the prevalence of meniscal damage in the general population and the association of meniscal tears with knee symptoms and with radiographic evidence of osteoarthritis. METHODS: We studied persons from Framingham, Massachusetts, who were drawn from census-tract data and random-digit telephone dialing. Subjects were 50 to 90 years of age and ambulatory; selection was not made on the basis of knee or other joint problems. We assessed the integrity of the menisci in the right knee on 1.5-tesla MRI scans obtained from 991 subjects (57% of whom were women). Symptoms involving the right knee were evaluated by questionnaire. RESULTS: The prevalence of a meniscal tear or of meniscal destruction in the right knee as detected on MRI ranged from 19% (95% confidence interval [CI], 15 to 24) among women 50 to 59 years of age to 56% (95% CI, 46 to 66) among men 70 to 90 years of age; prevalences were not materially lower when subjects who had had previous knee surgery were excluded. Among persons with radiographic evidence of osteoarthritis (Kellgren-Lawrence grade 2 or higher, on a scale of 0 to 4, with higher numbers indicating more definite signs of osteoarthritis), the prevalence of a meniscal tear was 63% among those with knee pain, aching, or stiffness on most days and 60% among those without these symptoms. The corresponding prevalences among persons without radiographic evidence of osteoarthritis were 32% and 23%. Sixty-one percent of the subjects who had meniscal tears in their knees had not had any pain, aching, or stiffness during the previous month. CONCLUSIONS: Incidental meniscal findings on MRI of the knee are common in the general population and increase with increasing age.

A new approach yields high rates of radiographic progression in knee osteoarthritis.

OBJECTIVE: Progression of knee osteoarthritis (OA) has typically been assessed in the medial tibiofemoral (TF) compartment on the anteroposterior (AP) or posteroanterior (PA) view. We propose a new approach using multiple views and compartments that is likely to be more sensitive to change and reveals progression throughout the knee. METHODS: We tested our approach in the Multicenter Osteoarthritis Study, a study of persons with OA or at high risk of disease. At baseline and 30 months, subjects provided PA (fixed flexion without fluoro) and lateral weight-bearing knee radiographs. Paired radiographs were read by 2 readers who scored joint space (JS) using a 0-3 atlas-based scale. When JS narrowed but narrowing did not reach a full grade on the scale, readers used half-grades. Change was scored in medial and lateral TF compartments on both PA and lateral views and in the patellofemoral (PF) joint on lateral view. A knee showed progression when there was at least a half-grade worsening in JS width in any compartment at followup. Disagreements were adjudicated by a panel of 3 readers. To validate progression, we tested definitions for TF progression to see if malalignment on long-limb radiographs at baseline (>or=3 degrees malaligned in any direction with nonmalaligned knees being reference) increased risk of progression. A valid definition of progression would show that malalignment strongly predicted progression. RESULTS: We studied 842 knees with either Kellgren-Lawrence grade>or=2 or PF OA at baseline in 606 subjects (age range 50-79 yrs, mean 63.9 yrs; 66.6% women). Mean body mass index was 31.9, and 32.8% of knees had frequent knee pain at baseline. Of these, 500 knees (59.4%) showed progression. Of the 500, 75 (15%) had progression only in the PF joint, while the remainder had progression in the TF joint. Malalignment increased the risk of overall progression in TF joint and increased the risk of half-grade progression, suggesting that half-grade progression had validity. CONCLUSION: PA and lateral views obtained in persons at high risk of OA progression can produce a cumulative incidence of progression above 50% at 30 months. Keys to increasing the yield include imaging PF and lateral compartments, using semiquantitative scales designed to detect change, and examining more than one radiographic view.

The aberrant anterior tibial artery: magnetic resonance appearance, prevalence, and surgical implications.

BACKGROUND: Injury of a popliteal fossa artery during orthopaedic knee surgery is very rare but has serious consequences. The risk of vascular trauma during orthopaedic procedures may be increased when there is abnormal branching of the popliteal artery with an aberrant anterior tibial artery originating above the popliteus muscle and coursing between the posterior tibial cortex and ventral margin of the popliteus muscle. Preoperative identification of this anatomical variant may help avoid these injuries. HYPOTHESIS: The aberrant anterior tibial artery is present in a substantial portion of the population and can be visualized by magnetic resonance imaging. STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: Retrospective review of 1116 consecutive knee magnetic resonance imaging studies was performed to evaluate the prevalence of an aberrant anterior tibial artery. Images were reviewed by 3 musculoskeletal radiologists. RESULTS: The aberrant anterior tibial artery was present in 23 of 1116 extremities for a prevalence of 2.1%. The aberrant artery was most easily identified on axial and sagittal magnetic resonance imaging scans. CONCLUSION: The aberrant anterior tibial artery is a relatively common normal variant, and magnetic resonance is an excellent modality for detection of the artery close to the posterior joint capsule and tibial cortex. CLINICAL RELEVANCE: The anatomy suggests the aberrant anterior tibial artery may be at greater risk of injury in orthopaedic procedures such as high tibial osteotomy, revision total knee arthroplasty, lateral meniscal repair, posterior cruciate ligament reconstruction, and screw fixation for tibial tubercle osteotomy. Careful inspection of preoperative magnetic resonance imaging studies may alert the surgeon to the presence of this anatomical variant.

Knee buckling: prevalence, risk factors, and associated limitations in function.

BACKGROUND: Knee buckling is common in persons with advanced knee osteoarthritis and after orthopedic procedures. Its prevalence in the community is unknown. OBJECTIVE: To examine the prevalence of knee buckling in the community, its associated risk factors, and its relation to functional limitation. DESIGN: Cross-sectional, population-based study. SETTING: The Framingham Osteoarthritis Study. PARTICIPANTS: 2351 men and women age 36 to 94 years (median, 63.5 years). MEASUREMENTS: Participants were asked whether they had experienced knee buckling or "giving way" and whether it led to falling. They were also asked about knee pain and limitations in function by using the Short Form-12 and Western Ontario and McMaster Universities Osteoarthritis Index, had isometric tests of quadriceps strength, and underwent weight-bearing radiography and magnetic resonance imaging of the knee. Radiographs were scored for osteoarthritis by using the Kellgren-Lawrence scale, and magnetic resonance images were read for anterior cruciate ligament tears. The relationship of buckling to functional limitation was examined by using logistic regression that adjusted for age, sex, body mass index, and knee pain severity. RESULTS: Two hundred seventy-eight participants (11.8%) experienced at least 1 episode of knee buckling within the past 3 months; of these persons, 217 (78.1%) experienced more than 1 episode and 35 (12.6%) fell during an episode. Buckling was independently associated with the presence of knee pain and with quadriceps weakness. Over half of those with buckling had no osteoarthritis on radiography. Persons with knee buckling had worse physical function than those without buckling, even after adjustment for severity of knee pain and weakness. For example, 46.9% of participants with buckling and 21.7% of those without buckling reported limitations in their work (adjusted odds ratio, 2.0 [95% CI, 1.5 to 2.7]). LIMITATION: Causal inferences are limited because of the study's cross-sectional design. CONCLUSION: In adults, knee buckling is common and is associated with functional loss.