Longitudinal study of the relationship between knee angle and tibiofemoral cartilage volume in subjects with knee osteoarthritis

OBJECTIVES: There is emerging evidence that knee alignment is associated with progression of osteoarthritis (OA). The aim of this study was to examine the relationship between baseline knee angle and the rate of cartilage loss in subjects with knee OA. METHODS: One hundred and seventeen subjects with knee OA had standing radiographs and MRI on their symptomatic knee at baseline and at the 1.9+/-0.2 yr follow-up. Knee cartilage volume was measured at baseline and follow-up. Knee angle was defined as the angle subtended by a line drawn through the mid-shaft of the femur with respect to one drawn through the mid-shaft of the tibia. RESULTS: At baseline, in the medial compartment, as the angle decreased (i.e. was less varus) the tibial and femoral cartilage volume increased. In the lateral compartment, as the angle became more valgus, there was a reduction in tibial and femoral cartilage volume. In the longitudinal study, for every 1 degrees increase in baseline varus angulation there was an average annual loss of medial femoral cartilage of 17.7 micro l [95% confidence interval (CI) 6.5-28.8]. Although not statistically significant, there was a trend for a similar relationship between loss of medial tibial cartilage volume and baseline knee angle. In the lateral compartment, there was an average loss of tibial cartilage volume of 8.0 micro l (95% CI 0.0-16.0) for every 1 degrees increase in valgus angle. CONCLUSIONS: Baseline knee angle is associated with the rate of cartilage loss in the knee. Further work will be needed to determine whether therapies aimed at modifying the knee angle will reduce the progression of knee OA.     

Compartment differences in knee cartilage volume in healthy adults

OBJECTIVE: It is unclear why there are compartmental differences in the risk of knee osteoarthritis (OA). We investigated whether there are compartment differences in the volume of knee cartilage in healthy persons and identified determinants of medial and lateral tibial cartilage volume. METHODS: A total of 166 healthy persons (age range 21-79 yrs, 58% female) with clinically and structurally normal knees were examined. Thickness and volume were determined for the medial and lateral tibial articular cartilages by processing images acquired in the sagittal plane using T1 weighted fat saturated magnetic resonance imaging on an independent work station. RESULTS: In every subject, the lateral tibial cartilage was thicker than medial cartilage (mean 6.43 +/- SD 1.25 mm vs 4.49 +/- 0.81 mm; p < 0.001), and the volume of cartilage was greater (2.34 +/- 0.70 ml vs 1.82 +/- 0.56 ml; p < 0.001). This effect persisted when values for men and women were analyzed separately. Both medial and lateral tibial cartilage volume and thickness were greater in men compared to women, independent of body mass index and bone size. The reduction in medial and lateral tibial cartilage volume and thickness was inversely related to the current level of physical activity. CONCLUSION: This study supports the knee compartment differences in cartilage volume recently reported in children. It is likely these differences are maintained throughout life. The possibility that the amount of knee cartilage in an individual is a risk factor for OA now needs to be tested in longitudinal studies.     

Association of cartilage defects with loss of knee cartilage in healthy, middle-age adults: a prospective study

OBJECTIVE: The significance of asymptomatic knee cartilage defects in healthy individuals is not known. The aim of this study was to examine the association between cartilage defects in the knee and cartilage volume both cross-sectionally and longitudinally in healthy, middle-age adults. METHODS: Eighty-six healthy men and women (mean +/- SD age 53.8 +/- 8.8 years) underwent T1-weighted fat-suppressed magnetic resonance imaging of their dominant knees at baseline and at the 2-year followup visit. Knee cartilage volume was measured. Cartilage defects were scored according to a grading system (0-4) and as present (a defect score of > or = 2) or absent in the medial and lateral tibiofemoral compartments. RESULTS: Cartilage defects in the medial and lateral tibiofemoral compartments were very common (in 61% and 43% of subjects, respectively). Those with cartilage defects had a 25% reduction in medial tibial cartilage volume, a 15% reduction in lateral tibial cartilage volume, and a 19% reduction in total femoral cartilage volume relative to those with no cartilage defects in cross-sectional analyses (all P < 0.05). In the medial tibiofemoral compartment, the annual loss of tibial cartilage in those with cartilage defects was 2.5% (95% confidence interval [95% CI] 2.2%, 3.1%) compared with an annual loss of tibial cartilage of 1.3% (95% CI 0.5%, 2.0%) in those with no defects (P = 0.028), independent of other known risk factors for osteoarthritis (OA). CONCLUSION: These data suggest that the presence of asymptomatic, non-full-thickness medial tibiofemoral cartilage defects identifies healthy individuals most likely to lose knee cartilage in the absence of radiographic knee OA. Thus, interventions aimed at reducing or reversing cartilage defects may reduce the risk of subsequent knee OA.     

The determinants of change in tibial cartilage volume in osteoarthritic knees

OBJECTIVE: The rate of change in osteoarthritic (OA) tibial articular cartilage and the factors that influence it are not known. We examined a cohort of subjects with OA to determine the change in articular knee cartilage volume over the course of 2 years and to identify factors which might influence such change and its rate. METHODS: One hundred twenty-three subjects with OA underwent baseline knee radiography and magnetic resonance imaging (MRI) on their symptomatic knee. They were followed up 2 years later with a repeat MRI of the same knee. Knee cartilage volume was measured at baseline and at followup. Risk factors assessed at baseline were tested for their association with change in knee cartilage volume over time. RESULTS: Mean +/- SD total tibial articular cartilage decreased by 5.3 +/- 5.2% (95% confidence interval [95% CI] 4.4%, 6.2%) per year. The annual percentages of loss of medial and lateral tibial cartilage were 4.7 +/- 6.5% (95% CI 3.6%, 5.9%) and 5.3 +/- 7.2% (95% CI 4.1%, 6.6%), respectively. Initial cartilage volume was the most significant determinant of loss of tibial cartilage in all compartments, while age was a significant determinant of lateral tibial cartilage loss, when possible confounders were accounted for. CONCLUSION: In OA, tibial cartilage volume is lost at a rate of approximately 5% per year. The main factor affecting cartilage loss is initial cartilage volume. Our results suggest that cartilage loss may be more rapid early in disease. Further study is required to determine whether the rate of cartilage loss in OA is steady or phasic, and to identify factors amenable to intervention to reduce cartilage loss.     

Meniscal tear as an osteoarthritis risk factor in a largely non-osteoarthritic cohort: a cross-sectional study

OBJECTIVE: To examine the associations between meniscal tear, knee structure, osteoarthritis (OA) risk factors, radiographic change, and symptoms in a largely non-osteoarthritic cohort. METHODS: This cross-sectional study included 294 subjects with mean age 47 (SD 6) years, body mass index (BMI) 28 (SD 5), and 58% were female. Meniscal tear, knee cartilage defect score, quantitative tibial and femoral cartilage volume, and tibial plateau bone area were determined using T1-weighted fat saturated magnetic resonance images. RESULTS: In multivariable analysis, prevalence of meniscal tear was significantly associated with age (OR 1.06 to 1.12/year, all p < 0.05), BMI (OR 1.06 to 1.11/kg/m(2), all p < 0.05 with the exception of the lateral anterior horn), sex (women vs men: OR 4.14 to 4.23, p < 0.01 at the medial and lateral meniscal body site), and family history of OA (OR 1.97 to 2.01, p < 0.05 at the lateral meniscal anterior and posterior horns). Meniscal tear was associated with a higher tibiofemoral cartilage defect score at lateral body and all medial sites, lower tibial and femoral cartilage volume at the lateral compartment, markedly higher prevalent radiographic OA at medial compartment, and greater tibial bone area. Moreover, meniscal tear at the lateral posterior and anterior horns was significantly associated with WOMAC pain, stiffness, and function scores. CONCLUSION: Meniscal tear at specific sites shares risk factors with knee OA. Importantly, meniscal tear is associated with cartilage defect, loss of cartilage volume, alteration in bone size, and prevalence of radiographic OA, suggesting that meniscal tear in non-OA subjects appears to be an early event in the disease process, and may be a risk factor for knee cartilage damage and articular structural changes.     

Comparison of patella cartilage volume and radiography in the assessment of longitudinal joint change at the patellofemoral joint

OBJECTIVE: To compare radiological assessment of the patellofemoral (PF) joint and cartilage volume as measured by magnetic resonance imaging (MRI) in a longitudinal study. METHODS: One hundred and two subjects with osteoarthritis (OA) had baseline and followup skyline and lateral radiographs and MRI of the same knee. Duration of followup was 1.94 +/- 0.23 years. Mid-patella joint space and narrowest joint space were measured on lateral PF radiographs. Minimum joint space in the lateral and medial facets was measured on skyline radiographs. Rate of progression of PF joint OA was measured quantitatively at each site. Patella cartilage volume was measured from the MRI. The rate of change in each radiographic measure was compared to the rate of change in patella cartilage volume. RESULTS: The average loss of patella cartilage was 133 +/- 143 microm(3)/yr (4.4%). The loss of joint space over the same period on lateral radiographs was 0.7 +/- 2.6 mm at the narrowest joint space and 0.2 +/- 3.8 mm at the mid-patella joint space. On the skyline radiographs, the loss of joint space at the medial facet was 0.4 +/- 3.9 mm and 0.2 +/- 3.4 mm at the lateral facet. Only change in narrowest joint space on the lateral PF radiographs correlated with change in patella cartilage volume (R = 0.22, p = 0.03). CONCLUSION: Our data suggest that narrowest joint space measured on lateral PF radiographs correlates best with loss of patella cartilage. Further work will be needed to determine how different radiological measures of the PF joint relate to the disease process in OA.     

Longitudinal study of changes in tibial and femoral cartilage in knee osteoarthritis

OBJECTIVE: Despite the increasing interest in knee cartilage volume as an outcome measure in studies of osteoarthritis (OA), it is unclear what components of knee cartilage will be most useful as markers of structural change in the tibiofemoral joint. This study was undertaken to longitudinally compare changes in femoral and tibial cartilage volume in patients with OA. METHODS: One hundred seventeen patients with knee OA (58.1% women; mean +/- SD age 63.7 +/- 10.2 years) were examined. Femoral and tibial cartilage volumes (medial and lateral tibiofemoral joints) were determined from T1-weighted fat-saturated magnetic resonance images of the knee from coronal views. RESULTS: The study population was followed up for a mean +/- SD of 1.9 +/- 0.2 years. In the medial tibiofemoral joint, the mean +/- SD loss of cartilage was 0.15 +/- 0.30 ml/year for femoral cartilage and 0.10 +/- 0.25 ml/year for tibial cartilage. In the lateral tibiofemoral joint, the average loss was 0.15 +/- 0.22 and 0.12 +/- 0.16 ml/year for femoral and tibial cartilage, respectively. There was a significant correlation between the degree of loss of tibial cartilage and the degree of loss of femoral cartilage, in both tibiofemoral joints (r = 0.81, P < 0.001 at the medial tibiofemoral joint; r = 0.71, P < 0.001 at the lateral tibiofemoral joint). CONCLUSION: Longitudinal changes in tibial cartilage and those in femoral cartilage are strongly related to one another. This suggests that in tibiofemoral disease, measuring tibial cartilage alone may be adequate, given the facts that measurements of the total femoral cartilage are less reproducible and there are difficulties inherent in identifying the most appropriate component of femoral cartilage to measure.     

The clinical correlates of articular cartilage defects in symptomatic knee osteoarthritis: a prospective study

OBJECTIVES: To determine whether articular cartilage defects are associated with cartilage loss and joint replacement in subjects with symptomatic knee osteoarthritis (OA). METHODS: One hundred and seventeen subjects with symptomatic knee OA underwent magnetic resonance imaging of their dominant knee at baseline and 2 yr later. Cartilage defects were identified as prevalent (defect score > or =2) in each knee compartment. Occurrence of joint replacement by 4 yr was documented. RESULTS: Cartilage defects were present in 81% of medial, 64% of lateral tibiofemoral compartments and 55% of patellar cartilages. Annual patellar cartilage loss was highest in those with defects compared with no defects (5.5% vs 3.2%, P = 0.01). Tibial cartilage loss was not associated with defects in the medial (4.6% vs 5.8%, P = 0.42) or lateral (4.7% vs 6.5%, P = 0.21) tibial cartilages. Higher total cartilage defect scores (8-15) were associated with a 6.0-fold increased risk of joint replacement over 4 yr compared with those with lower scores (2-7) (95% confidence interval 1.6, 22.3), independently of potential confounders. CONCLUSIONS: Articular cartilage defects are associated with disease severity in knee OA and predict patellar cartilage loss and knee replacement.     

Tibial and femoral cartilage changes in knee osteoarthritis

BACKGROUND: Despite the increasing interest in using knee cartilage volume as an outcome measure in studies of osteoarthritis (OA), it is unclear what components of knee cartilage will be most useful as markers of structure in the tibiofemoral (TF) joint. OBJECTIVE: To compare the changes that occur in femoral and tibial cartilage volume in normal and osteoarthritic knees and how they relate to radiological grade. METHODS: 82 subjects (44 female, 38 male, age range 35-69 years) with a spectrum of radiological knee OA were examined. Each subject had femoral and tibial cartilage volume in the medial and lateral TF joint determined from T(1) weighted fat saturated magnetic resonance images of the knee. Radiological grade of OA was determined from standing knee radiographs. RESULTS: There was strong correlation between femoral and tibial cartilage volume measured in both the medial (R=0.75, p<0.001) and lateral TF joint (R=0.77, p<0.001). Similar correlations persisted when those with normal and those with OA joints were examined separately at both the medial and lateral TF joint. For each increase in radiological grade of joint space narrowing (0-3), there was a mean (SD) reduction in tibial cartilage volume of 1.00 (0.32) ml in the medial compartment and 0.53 (0.25) ml in the lateral compartment, after adjusting for differences in bone size. Similar changes were seen in the femoral cartilage. CONCLUSIONS: The amounts of tibial and femoral cartilage are strongly related. It may be that for TF joint disease, measuring tibial cartilage alone may be adequate, given that measurements of the total femoral cartilage are less reproducible and the difficulties inherent in identifying the most appropriate component of femoral cartilage to measure.     

The effect of the knee adduction moment on tibial cartilage volume and bone size in healthy women

OBJECTIVES: There is considerable evidence that an abnormally high knee adductor moment is a characteristic of the gait patterns in people with knee osteoarthritis (OA). The aim of this study was to examine the relationship between the peak knee adduction moment during the early and late stance phases of gait, and medial and lateral tibial bone size and cartilage volume in healthy women. METHODS: Three-dimensional Vicon gait analyses and magnetic resonance imaging (MRI) were performed on 20 healthy women without knee OA. The external knee adduction moment was correlated with medial and lateral tibial bone size and cartilage volume for the dominant leg. RESULTS: The knee adduction moment significantly correlated with the bone size of the medial tibial plateau (r = 0.63, P < 0.005), but was not related to the bone size of the lateral plateau. No relationship was observed between the knee adduction moment and medial or lateral tibial cartilage volume. CONCLUSIONS: Although the knee adduction moment was positively associated with the bone size of the medial tibial plateau, it appeared to have little effect on cartilage volume in that compartment in healthy women. It may be that the effect of the knee adduction moment differs in healthy subjects compared with those with established knee OA.     

Smoking interacts with family history with regard to change in knee cartilage volume and cartilage defect development

OBJECTIVE: To describe the effects of smoking on change in knee cartilage volume and increases in knee cartilage defects, and to test for interaction between smoking and family history of osteoarthritis (OA). METHODS: Subjects with at least 1 parent having severe primary knee OA (offspring) and randomly selected controls without this history (a total of 325 subjects with a mean age of 45 years) were measured at baseline and 2.3 years later. Knee cartilage volume and defect score (on a 0-4 scale) were determined using T1-weighted fat-saturated magnetic resonance imaging. Smoking status and duration and number of cigarettes were recorded by questionnaire. RESULTS: In offspring, smoking was associated with annual change in medial and lateral tibial cartilage volume (beta = -2.20% and beta = -1.45%, respectively, for current smokers versus former smokers and those who had never smoked; beta = -0.07%/pack-year at both tibial sites, for smoking severity) in multivariate analysis. Smoking was also associated with increases (change >or=1) in medial and lateral tibiofemoral cartilage defect scores (odds ratio [OR] 4.91 and OR 2.98, respectively, for current smokers versus those who had never smoked; OR 9.90 and OR 12.98, respectively, for heavy smoking [total of >20 pack-years] versus never smoking) (all P < 0.05). In contrast, smoking was not associated with any of the above in controls except for change in lateral tibial cartilage volume. There was significant interaction between smoking and offspring-control status for change in medial tibial cartilage volume (P = 0.047) and increases in medial (P = 0.03) and lateral (P = 0.049) tibiofemoral cartilage defects. CONCLUSION: Smoking leads to knee cartilage loss and defect development primarily in individuals with a family history of knee OA. This provides evidence for a gene-environment interaction in the etiology of knee OA.     

How does tibial cartilage volume relate to symptoms in subjects with knee osteoarthritis?

BACKGROUND: No consistent relationship between the severity of symptoms of knee osteoarthritis (OA) and radiographic change has been demonstrated. OBJECTIVES: To determine the relationship between symptoms of knee OA and tibial cartilage volume, whether pain predicts loss of cartilage in knee OA, and whether change in cartilage volume over time relates to change in symptoms over the same period. METHOD: 132 subjects with symptomatic, early (mild to moderate) knee OA were studied. At baseline and 2 years later, participants had MRI scans of their knee and completed questionnaires quantifying symptoms of knee OA (knee-specific WOMAC: pain, stiffness, function) and general physical and mental health (SF-36). Tibial cartilage volume was determined from the MRI images. RESULTS: Complete data were available for 117 (89%) subjects. A weak association was found between tibial cartilage volume and symptoms at baseline. The severity of the symptoms of knee OA at baseline did not predict subsequent tibial cartilage loss. However, weak associations were seen between worsening of symptoms of OA and increased cartilage loss: pain (r(s) = 0.28, p = 0.002), stiffness (r(s) = 0.17, p = 0.07), and deterioration in function (r(s) = 0.21, p = 0.02). CONCLUSION: Tibial cartilage volume is weakly associated with symptoms in knee OA. There is a weak association between loss of tibial cartilage and worsening of symptoms. This suggests that although cartilage is not a major determinant of symptoms in knee OA, it does relate to symptoms.     

The determinants of change in patella cartilage volume in osteoarthritic knees

OBJECTIVE: The rate of change in patella articular cartilage and factors influencing it, in subjects with osteoarthritis (OA), is unknown. We performed a cohort study to determine this. METHODS: One hundred ten subjects with OA had baseline skyline and lateral radiographs and magnetic resonance imaging (MRI) on their knee. They were followed 2 years later with a repeat MRI of the same knee. Patella and tibial cartilage volume was measured at baseline and followup. Risk factors assessed at baseline were tested for their association with change in patella cartilage volume over time. RESULTS: The annual percentage loss of patella cartilage was 4.5 +/- 4.3%. Sex, body mass index (BMI), and pain score at baseline were associated with an increase in cartilage loss. The rate of patella cartilage loss was greater in women than men, 5.3% versus 3.5% (p < 0.03), independent of age, BMI, and pain score. No association was seen between change in patellar cartilage volume and change in either medial or lateral tibial cartilage volume (r = 0.02, p = 0.86 and r = 0.08, p = 0.43, respectively). CONCLUSION: In OA, patella cartilage volume is lost at 4.5 +/- 4.3% per year. The main factors affecting this are sex, BMI, and baseline pain score. The poor correlation between patella cartilage loss and cartilage loss in the tibial compartment suggests that the pathogenetic mechanisms for OA in the patellofemoral and tibiofemoral joint may differ. Further work will be required to determine whether the rate of patella cartilage loss in OA is steady or phasic, and to determine which factors can be modified to reduce cartilage loss.     

Serum levels of vitamin D,sunlight exposure,and knee cartilage loss in older adults: The Tasmanian older adult cohort study

Objective

To determine the associations between serum levels of vitamin D, sunlight exposure, and knee cartilage loss cross‐sectionally and longitudinally in older adults.

Methods

A total of 880 randomly selected subjects (mean age 61 years [range 51–79 years], 50% women) were studied at baseline, and 353 of these subjects were studied 2.9 years later. Serum levels of 25‐hydroxyvitamin D (25[OH]D) were assessed by radioimmunoassay, and sunlight exposure was assessed by questionnaire. T1‐weighted fat‐suppressed magnetic resonance imaging (MRI) of the right knee was performed to determine knee cartilage volume and defects. Knee radiographic osteoarthritis (OA) and knee pain were also assessed.

Results

The mean 25(OH)D serum level was 52.8 nmoles/liter at baseline (range 13–119 nmoles/liter). Winter sunlight exposure and serum 25(OH)D level were both positively associated with medial and lateral tibial cartilage volume, and a serum 25(OH)D level <50 nmoles/liter was associated with increased medial tibiofemoral joint space narrowing (all P < 0.05). Longitudinally, baseline serum 25(OH)D level predicted change in both medial and lateral tibial cartilage volume (β = +0.04% per annum per nmole/liter for both; P < 0.05), and change in serum 25(OH)D level was positively associated with change in medial tibial cartilage volume. These associations were consistent in subjects with radiographic OA and knee pain and/or in women, but not in men or in subjects without radiographic OA or knee pain.

Conclusion

Sunlight exposure and serum 25(OH)D levels are both associated with decreased knee cartilage loss (assessed by radiograph or MRI). This is best observed using the whole range of 25(OH)D levels rather than predefined cut points and implies that achieving vitamin D sufficiency may prevent and/or retard cartilage loss in knee OA.

     

Feasibility of T and Z scores from magnetic resonance imaging data for quantification of cartilage loss in osteoarthritis

OBJECTIVE: T scores (an indicator of the difference between patients and young healthy subjects) and Z scores (an indicator of the difference between patients and age-matched healthy subjects) are used in the diagnosis of osteoporosis and form the current basis for the definition of osteoporosis by the World Health Organization. We tested the feasibility of using T and Z scores derived from quantitative cartilage imaging with magnetic resonance imaging (MRI) for the diagnosis of osteoarthritis (OA). METHODS: High-resolution MR images of tibial cartilage were acquired from 126 young healthy adults (ages 20-35 years), 24 age-matched elderly healthy adults (ages 50-75 years), 7 OA patients prior to tibial osteotomy, and 7 OA patients prior to knee arthroplasty. Cartilage volume, thickness, surface area, and original joint surface area (before onset of disease) were determined in the medial and lateral tibia. RESULTS: The cartilage volume of the medial tibia of osteotomy patients with varus malalignment displayed moderate T scores (-1.0), and more negative T scores (-3.8) were observed in knee arthroplasty patients with varus malalignment. Normalization of the cartilage volume to the original joint surface area substantially enhanced the scores in patients undergoing osteotomy (-2.3) and in patients undergoing knee arthroplasty (-5.5), and this was superior to the normalization ratios of cartilage volume to body height and cartilage volume to body weight, in terms of distinguishing the loss of articular cartilage. CONCLUSION: Quantitative analysis of OA by MRI is feasible using T and Z scores. However, cartilage volume should be normalized to the individual joint surface area in order to maximize the discriminatory power of this technique for the diagnosis of OA.     

Rate of knee cartilage loss after partial meniscectomy

OBJECTIVE: Surgical removal of the meniscus of the knee is thought to be a risk factor for later appearance of knee osteoarthritis (OA). We examined whether there is a difference in cartilage loss in those who undergo a partial meniscectomy compared to healthy controls. METHODS: Eight patients who underwent a meniscectomy (5 partial medial, 3 partial lateral) and 13 controls with normal knee radiographs and magnetic resonance imaging (MRI) had an MRI at baseline and at a mean 28.6 +/- 7.6 months followup. Articular cartilage volumes were determined by processing images acquired in the sagittal plane using T1 weighted fat saturation MRI on an independent work station. RESULTS: The mean +/- SD of percentage rates of cartilage loss from baseline volume were 4.1 +/- 2.8% per year for the meniscectomy subjects and -2.3 +/- 3.0% per year for the controls (difference 6.5% per year, 95% CI 3.7-9.3% per year; p < 0.001). After adjustment for age, body mass index, and sex the difference increased slightly to 6.9% per year (95% CI 3.4-10.3%; p = 0.001). CONCLUSION: This study suggests that significant rates of cartilage loss are seen in subjects post partial meniscectomy compared with healthy controls. This may be a useful model in which to examine therapies to prevent OA.     

Reduced lower extremity vibratory perception in osteoarthritis of the knee

OBJECTIVE: Vibratory perception threshold (VPT) assesses a distinct yet related sensory pathway that has been associated with neuropathic arthropathy but has not been assessed in knee osteoarthritis (OA). The purpose of this study was to evaluate VPT in subjects with knee OA to determine whether the lower extremity afferent deficits observed in knee OA involve more than just proprioception. METHODS: Twenty-seven individuals with symptomatic and radiographic knee OA were compared with 14 age-matched normal subjects. VPT was assessed using a biothesiometer. Five sites of the lower extremity were evaluated. VPT of OA subjects was compared with VPT of normal subjects. RESULTS: VPT of the OA subjects was significantly reduced at all 5 testing sites compared with normal subjects (P<0.05 at all sites). VPT scores (mean+/-SEM volts) for OA subjects and normal subjects were as follows: first metatarsophalangeal joint (15.0+/-1.9 versus 6.4+/-0.9), medial malleolus (22.0+/-2.2 versus 12.3+/-1.4), lateral malleolus (22.3+/-2.0 versus 10.4+/-0.8), medial femoral condyle (25.8+/-1.8 versus 15.9+/-1.9), and lateral femoral condyle (27+/-1.9 versus 18.9+/-2.4). CONCLUSION: This was the first study to evaluate VPT in OA and demonstrate that VPT is reduced at the lower extremity of subjects with knee OA. The noted deficits in VPT may have significant implications in the neuromechanical pathophysiology of OA. VPT is a simple and reliable technique to measure sensory deficits in subjects with OA of the knee.     

Relationship between the area of cartilage shown on the magnetic resonance imaging middle-slice image of the medial and lateral tibial cartilages with cartilage volume and grade of osteoarthritis over time

OBJECTIVE: Knee cartilage volume measurement requires significant time and training. Simplifying the measurement may improve feasibility. We investigated whether the area of cartilage shown on the middle slice of the medial and lateral tibial cartilages on sagittal MRI correlates with radiological features of osteoarthritis (OA), cartilage volume, and longitudinal change in cartilage volume. METHODS: One hundred and seventy-three subjects (normal and osteoarthritic), who had serial magnetic resonance imaging (cartilage volume measured) and baseline weight-bearing antero-posterior radiographs of the same knee were examined. RESULTS: In the lateral compartment, with increasing grade of OA there was a significant reduction in cartilage area. In the medial compartment, this was true for medial joint-space narrowing (after adjusting for gender). There was a moderate to strong association between cartilage area and volume, especially in those with early or no OA. However, when change over time was examined, the strength of these relationships was weak. CONCLUSION: Our data suggests that cartilage area may provide a simple surrogate measure of cartilage volume, in cross-sectional studies, after adjustment for gender: especially in subjects with early disease. However, before it can be widely used, further investigation will be required.     

Risk factors for symptomatic knee osteoarthritis fifteen to twenty-two years after meniscectomy

OBJECTIVE: To evaluate the influence of age, sex, body mass index (BMI), extent of meniscal resection, cartilage status, and knee load on the development of radiographically evident osteoarthritis (OA) of the knee and knee symptoms after meniscal resection. METHODS: We evaluated 317 patients with no cruciate ligament injury (mean +/- SD age 54 +/- 11 years) who had undergone meniscal resection 15-22 years earlier (followup rate 70%), with radiographic and clinical examination. The Knee injury and Osteoarthritis Outcome Score was used to quantify knee-related symptoms. Sixty-eight unoperated subjects identified from national population records were included as a reference group. RESULTS: Symptomatic radiographic OA (corresponding to Kellgren/Lawrence grade > or =2) was present in 83 of 305 operated knees (27%) and 7 of 68 control knees (10%) (relative risk 2.6, 95% confidence interval [95% CI] 1.3-6.1). Patients who had undergone total meniscectomy and subjects with obesity (BMI > or =30) had a greater likelihood of tibiofemoral radiographic OA than those who had undergone partial meniscal resection and those with a BMI <25, respectively. Furthermore, degenerative meniscal tear, intraoperative cartilage changes, and lateral meniscectomy were associated with radiographic OA more frequently than were longitudinal tear, absence of cartilage changes, and medial meniscectomy, respectively. Symptomatic tibiofemoral or patellofemoral radiographic OA was associated with obesity, female sex, and degenerative meniscal tear. CONCLUSION: Contributing risk factors for OA development after meniscal resection are similar to risk factors for common knee OA. Systemic factors and local biomechanical factors interact. Obesity, female sex, and preexisting early-stage OA are features associated with poor self-reported and radiographic outcome. Partial meniscal resection is associated with less radiographic OA over time than is total meniscectomy.     

The association of meniscal pathologic changes with cartilage loss in symptomatic knee osteoarthritis

OBJECTIVE: To explore the role of meniscal tears and meniscal malposition as risk factors for subsequent cartilage loss in subjects with symptomatic osteoarthritis (OA). METHODS: Study subjects were patients with symptomatic knee OA from the Boston Osteoarthritis of the Knee Study. Baseline assessments included knee magnetic resonance imaging (MRI) with followup MRI at 15 and 30 months. Cartilage and meniscal damage were scored on MRI in the medial and lateral tibiofemoral joints using the semiquantitative whole-organ magnetic resonance imaging score. Tibiofemoral cartilage was scored on MR images of all 5 plates of each tibiofemoral joint, and the meniscal position was measured using eFilm Workstation software. A proportional odds logistic regression model with generalized estimating equations was used to assess the effect of each predictor (meniscal position factor and meniscal damage as dichotomous predictors in each model) on cartilage loss in each of the 5 plates within a compartment. Models were adjusted for age, body mass index (BMI), tibial width, and sex. RESULTS: We assessed 257 subjects whose mean +/- SD age was 66.6 +/- 9.2 years and BMI was 31.5 +/- 5.7 kg/m2; 42% of subjects were female, and 77% of knees had a Kellgren/Lawrence radiographic severity grade > or = 2. In the medial tibiofemoral joint, each measure of meniscal malposition was associated with an increased risk of cartilage loss. There was also a strong association between meniscal damage and cartilage loss. Since meniscal coverage and meniscal height diminished with subluxation, less coverage and reduced height also increased the risk of cartilage loss. CONCLUSION: This study highlights the importance of an intact and functioning meniscus in patients with symptomatic knee OA, since the findings demonstrate that loss of this function has important consequences for cartilage loss.