Ground reaction force patterns in knees with and without radiographic osteoarthritis and pain: descriptive analyses of a large cohort (the Multicenter Osteoarthritis Study)

OBJECTIVE

To compare ground reaction force patterns (GRF) during walking among legs defined by presence or absence of knee pain and/or radiographic knee osteoarthritis (ROA).

METHOD

Principal component analysis extracted major modes of variation (PCs) in GRF data from the Multicenter Osteoarthritis Study during self-paced walking. Legs were categorized as pain + ROA (n = 168), ROA only (n = 303), pain only (n = 476), or control (n = 1877). Relationships between group and GRF PCs were examined using Generalized Estimating Equations, adjusted for age, sex, body mass index, race, and clinic site with and without additional adjustment for gait speed.

RESULTS

With or without speed adjustment, pain + ROA had flatter vertical GRF waveforms than control (speed adjusted PC2 difference [95%CI]: -66 [-113,-20]), pain + ROA and ROA only had higher lateral GRF at impact and greater mid-stance medial GRF than control (speed adjusted PC3 difference: 9 [3,16] and 6 [2,10], respectively), and ROA only had higher early vs late medial GRF than control (speed adjusted PC2 difference: 7 [2,13]). Pain only had flatter vertical GRF waveforms and a smaller difference between anterior and posterior GRF than control only without speed adjustment.

CONCLUSION

In this large sample, sustained mid-stance loading and higher impact loads were identified in legs with ROA or ROA and pain, even when adjusting for differences in gait speed and other confounders. While it remains to be seen whether these features precede or result from ROA and pain, the presence of these patterns in the speed-adjusted models could have implications on gait interventions aimed to change joint loading.

Exerted running results in altered impact mechanics and footstrike patterns following gait retraining

Exertion may alter running mechanics and increase injury risk. Effects of exertion following gait-retraining are unknown.

OBJECTIVES

To determine how exertion effects load rates, footstrike, and cadence in runners following a transition to forefoot strike (FFS) or increased cadence (CAD) gait-retraining.

METHODS

33 (9 M, 24 F) healthy rearfoot strike runners were randomized into CAD or FFS groups. All runners received strengthening exercises and gait-retraining. 3D kinetic and kinematic motion analysis with instrumented treadmill at self-selected speed was performed at baseline & 1-week post-intervention, including an exerted run. Exertion was ≥17 on Borg's Rating of Perceived Exertion scale or voluntary termination of running.

RESULTS

Within group comparisons between fresh and exerted running: Cadence not affected in either group. Foot angle at contact became less plantarflexed in FFS (-2.2°, ±0.4) and was unchanged in CAD. Both groups increased vertical average load rate (FFS +16.9%, CAD +13.6%). CAD increased vertical stiffness (+8.6 kN/m). FFS reduced ankle excursion (1.8°). (p ≤ 0.05 for all values listed).

CONCLUSION

Both FFS and CAD exhibited increased load rates with exertion. Variables that may have increased load rates were different for each group. CAD runners had increased vertical stiffness while FFS runners had reduced plantarflexion at contact and reduced ankle dorsiflexion excursion.

Can Yoga or Physical Therapy for Chronic Low Back Pain Improve Depression and Anxiety Among Adults From a Racially Diverse, Low-Income Community? A Secondary Analysis of a Randomized Controlled Trial

OBJECTIVE

To determine and compare the effect of yoga, physical therapy (PT), and education on depressive and anxious symptoms in patients with chronic low back pain (CLBP).

DESIGN

Secondary analysis of a randomized controlled trial.

SETTING

Academic safety net hospital and 7 community health centers.

PARTICIPANTS

A total of 320 adults with CLBP.

INTERVENTION

Yoga classes, PT sessions, or an educational book.

OUTCOME MEASURE

Depression and anxiety were measured using the Patient Health Questionnaire and Generalized Anxiety Disorder 7-item Scale, respectively, at baseline, 12, and 52 weeks. We identified baseline and midtreatment (6-wk) factors associated with clinically meaningful improvements in depressive (≥3 points) or anxious (≥2 points) symptoms at 12 weeks.

RESULTS

Participants (female=64%; mean age, 46.0±10.7 years) were predominantly non-White (82%), low-income (<$30,000/year, 59%), and had not received a college degree (71%). Most participants had mild or worse depressive (60%) and anxious (50%) symptoms. At 12 weeks, yoga and PT participants experienced modest within-group improvements in depressive symptoms (mean difference [MD]=-1.23 [95% CI, -2.18 to -0.28]; MD=-1.01 [95% CI, -2.05 to -0.03], respectively). Compared with the education group, 12-week differences were not statistically significant, although trends favored yoga (MD=-0.71 [95% CI, -2.22 to 0.81]) and PT (MD= -0.32 [95% CI, -1.82 to 1.18]). At 12 weeks, improvements in anxious symptoms were only found in participants who had mild or moderate anxiety at baseline. Independent of treatment arm, participants who had 30% or greater improvement in pain or function midtreatment were more likely to have a clinically meaningful improvement in depressive symptoms (odds ratio [OR], 1.82 [95% CI, 1.03-3.22]; OR, 1.79 [95% CI, 1.06-3.04], respectively).

CONCLUSIONS

In our secondary analysis we found that depression and anxiety, common in this sample of underserved adults with CLBP, may improve modestly with PT and yoga. However, effects were not superior to education. Improvements in pain and function are associated with a decrease in depressive symptoms. More research is needed to optimize the integration of physical and psychological well-being in PT and yoga.

Is Heel Height Associated with Pain Exacerbations in Hip Osteoarthritis Patients?-Results from a Case-Crossover Study

The etiology of osteoarthritis (OA) pain exacerbations is not well understood. The purpose of this study is to evaluate the association of heel height and duration of wearing shoes with higher heels with pain exacerbations in people with hip OA. Eligible participants with symptomatic hip OA were instructed to complete online questionnaires every 10 days over a 90-day follow-up period. They were required to complete the questionnaire whenever they were experiencing hip pain exacerbation. Of 252 participants recruited, 137 (54.4%) contributed both case and control period data, and were included in the analysis. Wearing shoes with a heel height ≥ 2.5 cm during the past 24 h was associated with lower odds of pain exacerbations (OR: 0.54, 95% CI: 0.30 to 0.99). A longer duration (>6 h) of wearing shoes with heel height ≥ 2.5 cm was also associated with a lower risk of hip pain exacerbations (p for linear trend = 0.003). Wearing shoes with heel height ≥ 2.5 cm and longer duration in the past 24 h may be protective against hip pain exacerbations in people with symptomatic hip OA. Given the observational study nature, it would be prudent for this to be replicated in an independent data set.

Transition to forefoot strike reduces load rates more effectively than altered cadence

BACKGROUND

Excessive vertical impacts at landing are associated with common running injuries. Two primary gait-retraining interventions aimed at reducing impact forces are transition to forefoot strike and increasing cadence. The objective of this study was to compare the short- and long-term effects of 2 gait-retraining interventions aimed at reducing landing impacts.

METHODS

A total of 39 healthy recreational runners using a rearfoot strike and a cadence of ≤170 steps/min were randomized into cadence (CAD) or forefoot strike (FFS) groups. All participants performed 4 weeks of strengthening followed by 8 sessions of gait-retraining using auditory feedback. Vertical average load rates (VALR) and vertical instantaneous load rates (VILR) were calculated from the vertical ground reaction force curve. Both cadence and foot strike angle were measured using 3D motion analysis and an instrumented treadmill at baseline and at 1 week, 1 month, and 6 months post retraining.

RESULTS

ANOVA revealed that the FFS group had significant reductions in VALR (49.7%) and VILR (41.7%), and changes were maintained long term. Foot strike angle in the FFS group changed from 14.2° dorsiflexion at baseline to 3.4° plantarflexion, with changes maintained long term. The CAD group exhibited significant reduction only in VALR (16%) and only at 6 months. Both groups had significant and similar increases in cadence at all follow-ups (CAD, +7.2% to 173 steps/min; and FFS, +6.1% to 172 steps/min).

CONCLUSION

Forefoot strike gait-retraining resulted in significantly greater reductions in VALR and similar increases in cadence compared to cadence gait-retraining in the short and long term. Cadence gait-retraining resulted in small reductions in VALR at only the 6-month follow-up.

The Association of Parity with Greater Dynamic Pronation of the Feet

BACKGROUND

Postpartum women are at increased risk for lower limb musculoskeletal disorders. Foot arch collapse following pregnancy has been reported as a mechanism for this increased risk. However, dynamic changes during gait in postpartum women have not been reported. Therefore, we assessed the association between parity and dynamic foot pronation during gait.

OBJECTIVE

To determine (1) if there is an association between parity and dynamic foot pronation (center of pressure excursion index, CPEI) during gait; and (2) the extent to which there is a dose-effect of parity on foot pronation.

DESIGN

The Multicenter Osteoarthritis Study (MOST) Study is a longitudinal cohort study of adults with or at risk for knee osteoarthritis (OA).

SETTING

Two communities in the United States, Birmingham, Alabama and Iowa City, Iowa.

INTERVENTIONS

Not applicable PARTICIPANTS: A population-based sample of 1177 MOST participants who were female, had complete CPEI and parity data and completed the baseline, 30- and 60-month visits.

MAIN OUTCOME MEASURES

Odds of a one quintile decrease in CPEI by parity group and mean CPEI by parity group.

RESULTS

In 1177 women, mean age was 67.7 years and mean body mass index (BMI) was 30.6 kg/m² . As parity increased, there was significantly greater foot pronation, lower mean CPEI: 19.1 (18.2-20.1), 18.9 (18.4-19.4), 18 (17.5-18.6) to 17.5 (16.4-18.6) in the 0 to 4 and >5 children groups, respectively; (P = .002), which remained significant after adjusting for race and clinic site (P = .005). There was a positive linear trend (β = 1.08, 1.03-1.14) in odds ratios of a one quintile decrease in CPEI (greater pronation) with increasing parity level (P = .004), which remained significant after adjusting for race and clinic site (P = .01). After adjusting for age and BMI, these two associations were no longer statistically significant.

CONCLUSIONS

This study indicates a positive correlation between parity and greater dynamic pronation of the feet.

Step Rate and Worsening of Patellofemoral and Tibiofemoral Joint Osteoarthritis in Women and Men: The Multicenter Osteoarthritis Study

OBJECTIVE

To determine the association of self-selected walking step rate with worsening of cartilage damage in the patellofemoral (PF) joint and tibiofemoral (TF) joint compartments at a 2-year follow-up visit.

METHODS

The Multicenter Osteoarthritis Study (MOST) is a prospective cohort of men and women with or at risk of knee osteoarthritis. Self-selected step rate was measured using an instrumented GAITRite walkway (CIR Systems) at the 60-month visit. Cartilage damage was semiquantitatively graded on magnetic resonance images at the 60- and 84-month visits in the medial and lateral PF and TF compartments. Step rate was divided into quartiles, and logistic regression was used to determine the association of step rate with the risk of worsening cartilage damage in men and women separately. Analyses were adjusted for age, body mass index, and knee injury/surgery.

RESULTS

A total of 1,089 participants were included. Mean ± SD age was 66.9 ± 7.5 years, mean ± SD body mass index was 29.6 ± 4.7 kg/m2 , and 62.3% of the participants were women. Women with the lowest step rate had increased risk of lateral PF (risk ratio [RR] 2.1 [95% confidence interval (95% CI) 1.1-3.8]) and TF (RR 1.8 [95% CI 1.1-2.9]) cartilage damage worsening 2 years later compared to those with the highest step rate. Men with the lowest step rate had increased risk of medial TF cartilage damage worsening 2 years later (RR 2.1 [95% CI 1.1-3.9]).

CONCLUSION

Lower step rate was associated with increased risk of cartilage damage worsening in the lateral PF and TF compartments in women and worsening medial TF joint damage in men. Future research is necessary to understand the influence of step rate manipulation on joint biomechanics in women and men.

Association of Varus Knee Thrust During Walking With Worsening Western Ontario and McMaster Universities Osteoarthritis Index Knee Pain: A Prospective Cohort Study

OBJECTIVE

To investigate the 2-year association of varus knee thrust observed during walking to the odds of worsening Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) knee pain in older adults with or at risk of osteoarthritis (OA).

METHODS

Video recordings of self-paced walking trials of Multicenter Osteoarthritis Study participants were assessed for the presence of varus thrust at baseline. Knee pain was assessed using the WOMAC questionnaire at baseline and at 2 years. Logistic regression was used to estimate the odds of worsening knee pain (defined as either any increase in WOMAC score or as clinically important worsening), adjusting for age, sex, race, body mass index, clinic site, gait speed, and static knee alignment. Analyses were repeated, stratified by baseline radiographic OA status and among the subset of knees without baseline WOMAC pain.

RESULTS

A total of 1,623 participants contributed 3,204 knees. Varus thrust was observed in 31.5% of knees. Knees with varus thrust had 1.44 times (95% confidence interval [95% CI] 1.19-1.73) the odds of any worsening and 1.37 times (95% CI 1.11-1.69) the odds of clinically important worsening WOMAC pain compared to knees without thrust. Knees with thrust without baseline WOMAC pain had 2.01 times (95% CI 1.47-2.74) the odds of incident total pain.

CONCLUSION

Results indicate that varus thrust is a risk factor for worsening and incident knee pain. Targeting varus thrust through noninvasive therapies could prevent development or worsening of knee pain in older adults with or at risk for knee OA.

Varus thrust during walking and the risk of incident and worsening medial tibiofemoral MRI lesions: the Multicenter Osteoarthritis Study

OBJECTIVE

To determine the association of varus thrust during walking to incident and worsening medial tibiofemoral cartilage damage and bone marrow lesions (BMLs) over 2 years in older adults with or at risk for osteoarthritis (OA).

METHOD

Subjects from the Multicenter Osteoarthritis Study (MOST) were studied. Varus thrust was visually assessed from high-speed videos of forward walking trials. Baseline and two-year MRIs were acquired from one knee per subject and read for cartilage loss and BMLs. Logistic regression with generalized estimating equations was used to estimate the odds of incident and worsening cartilage loss and BMLs, adjusting for age, sex, race, body mass index (BMI), and clinic site. The analysis was repeated stratified by varus, neutral, and valgus alignment.

RESULTS

1007 participants contributed one knee each. Varus thrust was observed in 29.9% of knees. Knees with thrust had 2.17 [95% CI: 1.51, 3.11] times the odds of incident medial BML, 2.51 [1.85, 3.40] times the odds of worsening medial BML, and 1.85 [1.35, 2.55] times the odds of worsening medial cartilage loss. When stratified by alignment, varus knees also had significantly increased odds of these outcomes.

CONCLUSION

Varus thrust observed during walking is associated with increased odds of incident and worsening medial BMLs and worsening medial cartilage loss. Increased odds of these outcomes persist in varus-aligned knees.

The Association of Forefoot Varus Deformity with Patellofemoral Cartilage Damage in Older Adult Cadavers

Forefoot alignment may contribute to patellofemoral joint (PFJ) osteoarthritis (OA) via its influence on the closed chain kinematics of the lower limb. The purpose of this cadaveric study was to investigate the relationship between forefoot varus and ipsilateral cartilage damage in the medial and lateral PFJ. Forefoot alignment measurements were obtained from the feet of 25 cadavers (n = 50). Cartilage damage in the medial and lateral PFJ of each knee was scored using the Outerbridge scale. The relative odds of medial and lateral PFJ cartilage damage in limbs with forefoot varus and valgus were determined using logistic regression. The relationship between increasing varus alignment and increasing odds of medial and lateral PFJ cartilage damage was assessed. Of the 51% of limbs with forefoot varus, 91.3% had medial, and 78.3% had lateral PFJ cartilage damage, compared with 54.6% and 68.2% of those with forefoot valgus. The former also had 3.0 times (95% CI 1.2, 7.7) the odds of medial PFJ damage; no association was found with lateral damage (OR 1.4, 95% CI 0.7, 3.0). Feet in the highest tertile of varus alignment had 3.9 times (95% CI 10, 15.3, P = 0.058) the odds of medial PFJ damage as those in the lowest tertile. The results of this study suggest a relationship between forefoot varus and medial PFJ cartilage damage in older adults. As forefoot varus may be modified with foot orthoses, these findings indicate a potential role for orthoses in the treatment of medial PFJ OA. Anat Rec, 300:1032-1038, 2017. © 2016 Wiley Periodicals, Inc.

Are Pressure Time Integral and Cumulative Plantar Stress Related to First Metatarsophalangeal Joint Pain? Results From a Community-Based Study

OBJECTIVE

To examine the relationship between plantar stress over a step, cumulative plantar stress over a day, and first metatarsophalangeal (MTP) joint pain among older adults.

METHODS

Plantar stress and first MTP pain were assessed within the Multicenter Osteoarthritis Study. All included participants were asked if they had pain, aching, or stiffness at the first MTP joint on most days for the past 30 days. Pressure time integral (PTI) was quantified as participants walked on a pedobarograph, and mean steps per day were obtained using an accelerometer. Cumulative plantar stress was calculated as the product of regional PTI and mean steps per day. Quintiles of hallucal and second metatarsal PTI and cumulative plantar stress were generated. The relationship between predictors and the odds ratio of first MTP pain was assessed using a logistic regression model.

RESULTS

Feet in the quintile with the lowest hallux PTI had 2.14 times increased odds of first MTP pain (95% confidence interval [95% CI] 1.42-3.25, P < 0.01). Feet in the quintile with the lowest second metatarsal PTI had 1.50 times increased odds of first MTP pain (95% CI 1.01-2.23, P = 0.042). Cumulative plantar stress was unassociated with first MTP pain.

CONCLUSION

Lower PTI was modestly associated with increased prevalence of frequent first MTP pain at both the hallux and second metatarsal. Lower plantar loading may indicate the presence of an antalgic gait strategy and may reflect an attempt at pain avoidance. The lack of association with cumulative plantar stress may suggest that patients do not limit their walking as a pain-avoidance mechanism.

Relation of Step Length to Magnetic Resonance Imaging-Detected Structural Damage in the Patellofemoral Joint: The Multicenter Osteoarthritis Study

OBJECTIVE

To investigate the relationship of step length to the sex-specific prevalence and worsening of magnetic resonance imaging (MRI)-detected structural damage in the patellofemoral (PF) joint among a cohort of older women and men with or at risk of knee osteoarthritis (OA).

METHODS

The Multicenter Osteoarthritis Study is a cohort study of persons ages 50-79 years with or at risk of knee OA. Step length was assessed using the GAITRite walkway (CIR Systems) at the 60-month visit, and cartilage damage and bone marrow lesions (BMLs) were graded on MRI at the 60- and 84-month visits. Step length was divided into sex-specific quintiles, and the relationship of step length to the prevalence and worsening of cartilage damage and BMLs in the PF joint was examined using logistic regression, adjusting for age, body mass index (BMI), leg length, and tibiofemoral joint structural damage.

RESULTS

In 1,053 knees, 4,094 and 4,083 PF joint subregions were studied for the cartilage and BML analyses, respectively. Mean ± SD age was 65.6 ± 8.1 years and mean ± SD BMI was 29.1 ± 4.7 kg/m(2) ; 62% of participants were female. In women, compared to those with the shortest step length, those with the longest step length had 0.62 (95% confidence interval [95% CI] 0.43-0.88) and 0.59 (95% CI 0.40-0.87) times the odds of cartilage damage and BMLs, respectively. There was no cross-sectional association in men, and no longitudinal association in either sex.

CONCLUSION

Women with PF joint structural damage may adapt their gait by shortening their step length, but this may not be sufficient to reduce the risk of worsening damage over time.

The relation of MRI-detected structural damage in the medial and lateral patellofemoral joint to knee pain: the Multicenter and Framingham Osteoarthritis Studies

OBJECTIVE

To examine the relation of cartilage loss and bone marrow lesions (BMLs) in the medial and lateral patellofemoral joint (PFJ) to knee pain.

METHODS

We categorized the location of full-thickness cartilage loss and BMLs in the PFJ on knee magnetic resonance imaging (MRIs) from the Multicenter Osteoarthritis (MOST) and Framingham Osteoarthritis (FOA) Studies as no damage, isolated medial, isolated lateral, or both medial and lateral (mixed). We determined the relation of MRI lesions in each PFJ region to prevalent knee pain. Differences in knee pain severity were compared among categories of PFJ full-thickness cartilage loss and BMLs using quantile regression.

RESULTS

In MOST (n = 1137 knees), compared with knees without full-thickness cartilage loss, knees with isolated lateral or mixed PFJ full-thickness cartilage loss had 1.9 (1.3, 2.8) and 1.9 (1.2, 2.9) times the odds of knee pain, respectively, while isolated medial cartilage loss had no association with knee pain. BMLs in both the medial and lateral PFJ had 1.5 (1.1, 2.0) times the odds of knee pain compared with knees without BMLs. Knee pain severity was lowest in knees with isolated medial PFJ cartilage loss or BMLs. In FOA (n = 934 knees), neither isolated medial nor lateral cartilage loss was associated with knee pain, whereas isolated BMLs in either region were associated with pain.

CONCLUSIONS

Results were not completely concordant but suggest that knee pain risk and severity is greatest with cartilage loss isolated to (MOST) or inclusive of (MOST and FOA) the lateral PFJ. While BMLs in either the medial or lateral PFJ are related to pain.

Daily walking and the risk of incident functional limitation in knee osteoarthritis: an observational study

OBJECTIVE

Physical activity is recommended to mitigate functional limitations associated with knee osteoarthritis (OA). However, it is unclear whether walking on its own protects against the development of functional limitation.

METHODS

Walking over 7 days was objectively measured as steps/day within a cohort of people with or at risk of knee OA from the Multicenter Osteoarthritis Study. Incident functional limitation over 2 years was defined by performance-based (gait speed <1.0 meter/second) and self-report (Western Ontario and McMaster Universities Osteoarthritis Index physical function score >28 of 68) measures. We evaluated the association of steps/day at baseline with developing functional limitation 2 years later by calculating risk ratios adjusted for potential confounders. The number of steps/day that best distinguished risk for developing functional limitation was estimated from the maximum distance from chance on receiver operating characteristic curves.

RESULTS

Among 1,788 participants (mean age 67 years, mean body mass index 31 kg/m(2) , 60% women), each additional 1,000 steps/day was associated with a 16% and 18% reduction in incident functional limitation by performance-based and self-report measures, respectively. Walking <6,000 and <5,900 steps/day were the best thresholds to distinguish incident functional limitation by performance-based (sensitivity 67.3%, specificity 71.8%) and self-report (sensitivity 58.7%, specificity 68.9%) measures, respectively.

CONCLUSION

More walking was associated with less risk of functional limitation over 2 years. Walking >6,000 steps/day provides a preliminary estimate of the level of walking activity to protect against developing functional limitation in people with or at risk of knee OA.

Association of hip and pelvic geometry with tibiofemoral osteoarthritis: multicenter osteoarthritis study (MOST)

OBJECTIVE

Lateral tibiofemoral osteoarthritis (OA) is overall less common than medial tibiofemoral OA, but it is more prevalent in women. This may be explained by sex differences in hip and pelvic geometry. The aim of this study is to explore sex differences in hip and pelvic geometry and determine if such parameters are associated with the presence of compartment-specific knee OA.

METHODS

This case-control study reports on 1,328 hips/knees from 664 participants and is an ancillary to the Multicenter Osteoarthritis Study (MOST). Of the 1,328 knees, 219 had lateral OA, 260 medial OA, and 849 no OA. Hip and pelvic measurements were taken from full-limb radiographs on the ipsilateral side of the knee of interest. After adjusting for covariates, means were compared between sexes and also between knees with medial and lateral OA vs no OA using separate regression models.

RESULTS

Women were shown to have a reduced femoral offset (FO) (mean 40.9 mm vs 45.9 mm; P = 0.001) and more valgus neck-shaft angle (mean 128.4° vs 125.9°; P < 0.001) compared to men. Compared to those with no OA, knees with lateral OA were associated with a reduced FO (P = 0.012), increased height of hip centre (HHC) (P = 0.003), more valgus neck-shaft angle (P = 0.042), and increased abductor angle (P = 0.031). Knees with medial OA were associated with a more varus neck-shaft angle (P = 0.043) and a decreased abductor angle (P = 0.003).

CONCLUSION

These data suggest anatomical variations at the hip and pelvis are associated with compartment-specific knee OA and may help to explain sex differences in patterns of knee OA.

Valgus malalignment is a risk factor for lateral knee osteoarthritis incidence and progression: findings from the Multicenter Osteoarthritis Study and the Osteoarthritis Initiative

OBJECTIVE

To study the effect of valgus malalignment on knee osteoarthritis (OA) incidence and progression.

METHODS

We measured the mechanical axis from long limb radiographs from the Multicenter Osteoarthritis Study (MOST) and the Osteoarthritis Initiative (OAI) to define limbs with valgus malalignment (mechanical axis of ≥1.1° valgus) and examined the effect of valgus alignment versus neutral alignment (neither varus nor valgus) on OA structural outcomes. Posteroanterior radiographs and knee magnetic resonance (MR) images were obtained at the time of the long limb radiograph and at followup examinations. Lateral progression was defined as an increase in joint space narrowing (on a semiquantitative scale) in knees with OA, and incidence was defined as new lateral narrowing in knees without radiographic OA. We defined lateral cartilage damage and progressive meniscal damage as increases in cartilage or meniscus scores at followup on the Whole-Organ Magnetic Resonance Imaging Score scale (for the MOST) or the Boston Leeds Osteoarthritis Knee Score scale (for the OAI). We used logistic regression with adjustment for age, sex, body mass index, and Kellgren/Lawrence grade, as well as generalized estimating equations, to evaluate the effect of valgus alignment versus neutral alignment on disease outcomes. We calculated odds ratios (ORs) and 95% confidence intervals (95% CIs).

RESULTS

We studied 5,053 knees (881 valgus) of subjects in the MOST cohort and 5,953 knees (1,358 valgus) of subjects in the OAI cohort. In both studies, all strata of valgus malalignment, including 1.1° to 3° valgus, were associated with an increased risk of lateral disease progression. In knees without radiographic OA, valgus alignment >3° was associated with incidence (e.g., in the MOST, adjusted OR 2.5 [95% CI 1.0-5.9]). Valgus alignment >3° was also associated with cartilage damage on MR imaging in knees without OA (e.g., in the OAI, adjusted OR 5.9 [95% CI 1.1-30.3]).We found a strong relationship of valgus malalignment with progressive lateral meniscal damage.

CONCLUSION

Valgus malalignment increases the risk of knee OA radiographic progression and incidence as well as the risk of lateral cartilage damage. It may cause these effects, in part, by increasing the risk of meniscal damage.

Do radiographic disease and pain account for why people with or at high risk of knee osteoarthritis do not meet physical activity guidelines?

OBJECTIVE

Knee osteoarthritis (OA) and pain are assumed to be barriers to meeting physical activity guidelines, but this has not been formally evaluated. The purpose of this study was to determine the proportions of people with and those without knee OA and knee pain who meet recommended physical activity levels through walking.

METHODS

We performed a cross-sectional analysis of community-dwelling adults from the Multicenter Osteoarthritis Study who had or who were at high risk of knee OA. Participants wore a StepWatch activity monitor to record steps per day for 7 days. The proportion of participants who met the recommended physical activity levels was defined as those accumulating≥150 minutes per week at ≥100 steps per minute in bouts lasting ≥10 minutes. These proportions were also determined for those with and those without knee OA, as classified by radiography and by severity of knee pain.

RESULTS

Of the 1,788 study participants (mean±SD age 67.2±7.7 years, mean±SD body mass index 30.7±6.0 kg/m2, 60% women), lower overall percentages of participants with radiographic knee OA and knee pain met recommended physical activity levels. However, these differences were not statistically significant between those with and those without knee OA; 7.3% and 10.1% of men (P=0.34) and 6.3% and 7.8% of women (P=0.51), respectively, met recommended physical activity levels. Similarly, for those with moderate/severe knee pain and those with no knee pain, 12.9% and 10.9% of men (P=0.74) and 6.7% and 11.0% of women (P=0.40), respectively, met recommended physical activity levels.

CONCLUSION

Disease and pain have little impact on achieving recommended physical activity levels among people with or at high risk of knee OA.

Anatomical origin of forefoot varus malalignment

BACKGROUND

Forefoot varus malalignment is clinically defined as a nonweightbearing inversion of the metatarsal heads relative to a vertical bisection of the calcaneus in subtalar joint neutral. Although often targeted for treatment with foot orthoses, the etiology of forefoot varus malalignment has been debated and may involve an unalterable bony torsion of the talus.

METHODS

Forty-nine feet from 25 cadavers underwent bilateral measurement of forefoot alignment using adapted clinical methods, followed by dissection and measurement of bony talar torsion. The relationship between forefoot alignment and talar torsion was determined using the Pearson correlation coefficient.

RESULTS

Mean ± SD forefoot alignment was -0.9° ± 9.8° (valgus) and bony talar torsion was 32.8° ± 5.3° valgus. There was no association between forefoot alignment and talar torsion (r = 0.18; 95% confidence interval, -0.11 to 0.44; P = .22).

CONCLUSIONS

These findings may have implications for the treatment of forefoot varus since they suggest that the source of forefoot varus malalignment may be found in an alterable soft-tissue deformity rather than in an unalterable bony torsion of the talus.

Breaking the Law of Valgus: the surprising and unexplained prevalence of medial patellofemoral cartilage damage

OBJECTIVES

To compare the prevalence of medial and lateral patellofemoral (PF) cartilage damage in three large osteoarthritis (OA) studies and determine the relationship of this damage to varus, neutral and valgus knee alignment.

METHODS

In the Boston OA of the Knee, Framingham OA and Multicenter OA studies, MRIs were read for cartilage morphology at the medial and lateral patella and trochlea femoris using Whole-Organ MRI Scores (WORMS). WORMS scores ≥2 (any cartilage defect), ≥3 (areas of partial thickness loss), ≥4 (diffuse partial thickness loss) and ≥5 (extensive full thickness loss) were all variously considered as thresholds to identify damage that may indicate OA. Full-limb radiographs were measured for mechanical alignment, and varus (<-2°), neutral (-2° to 2°) and valgus (>2°) knees were identified.

RESULTS

The prevalence of medial PF cartilage damage exceeded that of lateral damage in all three studies and according to nearly every threshold. Only among severely involved knees (WORMS ≥4 or ≥5) did the prevalence of lateral PF cartilage damage approximate that of medial damage. The high prevalence of medial PF damage persisted in all strata of knee alignment. Even among knees with valgus alignment, the prevalence of lateral PF cartilage damage equalled or surpassed that of medial PF damage only when the threshold was specific to severely involved knees.

CONCLUSIONS

Medial PF cartilage damage is at least as prevalent within these older adult populations as lateral PF cartilage damage.

Realignment treatment for medial tibiofemoral osteoarthritis: randomised trial

OBJECTIVES

The objective of this 30-week randomised crossover trial was to determine whether a multi-modal realignment treatmentwould be successful in relieving pain and improving function among persons with medial tibiofemoral osteoarthritis (OA).

METHODS

The authors conducted a double-blind randomised crossover trial of a multi-modal realignment treatment for medial tibiofemoral OA. Trial participants met American College of Rheumatology criteria for OA, with knee pain, aching or stiffness on most days of the past month and radiographic evidence of a definite osteophyte with predominant medial tibiofemoral OA. The authors tested two different treatments: (A) control treatment consisting of a neutral knee brace (no valgus angulation), flat unsupportive foot orthoses and shoes with a flexible mid-sole; and (B) active treatment consisting of a valgus knee brace, customised neutral foot orthoses and shoes designed for motion control. For each subject, the trial lasted 30 weeks, including 12 weeks each of active treatment and control treatment separated by a 6-week washout period. The primary outcome of the linear regression model was change in knee pain and function, as assessed by the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC).

RESULTS

80 participants with medial tibiofemoral OA were randomised. Their mean age was 62 years, their mean body mass index was 34 kg/m(2) and their mean WOMAC Pain score was 9.2 (0-20 scale). There was no evidence of a carryover effect. The regression model demonstrated that the mean difference in pain between the active treatment and the control treatment was -1.82 units (95% CI -3.05 to -0.60; p=0.004) on the WOMAC Pain scale, indicating a small but statistically significant decrease in pain with the multi-modal active treatment. For WOMAC Function, the realignment intervention had a non-significant effect on function, with a -2.90 unit decrease (95% CI -6.60 to 0.79) compared with the control condition (p=0.12).

CONCLUSION

Multi-modal realignment treatment decreases pain in persons with medial tibiofemoral OA.

The association of obesity with walking independent of knee pain: the multicenter osteoarthritis study

Practice guidelines recommend addressing obesity for people with knee OA, however, the association of obesity with walking independent of pain is not known. We investigated this association within the Multicenter Osteoarthritis Study, a cohort of older adults who have or are at high risk of knee OA. Subjects wore a StepWatch to record steps taken over 7 days. We measured knee pain from a visual analogue scale and obesity by BMI. We examined the association of obesity with walking using linear regression adjusting for pain and covariates. Of 1788 subjects, the mean steps/day taken was 8872.9 ± 3543.4. Subjects with a BMI ≥35 took 3355 fewer steps per day independent of knee pain compared with those with a BMI ≤25 (95% CI -3899, -2811). BMI accounted for 9.7% of the variability of walking while knee pain accounted for 2.9%. BMI was associated with walking independent of knee pain.

Quadriceps weakness, patella alta, and structural features of patellofemoral osteoarthritis

OBJECTIVE

To determine the relationship between quadriceps weakness and cartilage damage and bone marrow lesions (BMLs) in the patellofemoral joint (PFJ) and if this relationship is modified by patella alta.

METHODS

The Multicenter Osteoarthritis Study is a cohort study of persons ages 50-79 years with or at risk of knee osteoarthritis. Concentric knee extensor strength was measured using an isokinetic dynamometer. Patella alta was measured using the Insall-Salvati ratio (ISR) on the lateral radiograph, and cartilage damage and BMLs were graded on magnetic resonance imaging in the PFJ. We determined the association between quadriceps weakness with cartilage damage and BMLs in the PFJ among knees with (ISR ≥1.2) and without (ISR <1.2) patella alta using multiple binomial regression.

RESULTS

A total of 807 knees were studied (mean age 62 years, body mass index 30 kg/m(2) , ISR 1.10) and 64% were from women. Compared with the knees in the highest strength tertile, those in the lowest had 10.2% (95% confidence interval [95% CI] 3, 18), 9.1% (95% CI 2, 16), and 7.1% (95% CI 1, 13) higher prevalence of lateral PFJ cartilage damage, medial PFJ cartilage damage, and lateral PFJ BMLs, respectively. The association between quadriceps weakness with cartilage damage and BMLs was not different between knees with and without patella alta in the lateral PFJ.

CONCLUSION

Quadriceps weakness was associated with PFJ cartilage damage and BMLs. While both patella alta and quadriceps weakness were associated with PFJ damage, the combination of the two was not associated with more damage than either of these factors alone.

Association of flat feet with knee pain and cartilage damage in older adults

OBJECTIVE

To assess the cross-sectional relation of planus foot morphology to ipsilateral knee pain and compartment-specific knee cartilage damage in older adults.

METHODS

In the Framingham Studies, we adapted the Staheli Arch Index (SAI) to quantify standing foot morphology from pedobarographic recordings. We inquired about knee pain and read 1.5 T magnetic resonance image (MRI) scans using the Whole-Organ MRI Score. Logistic regression compared the odds of knee pain among the most planus feet to the odds among all other feet, and estimated odds within categories of increasing SAI. Similar methods estimated the odds of cartilage damage in each knee compartment. Generalized estimating equations adjusted for age, sex, body mass index, and nonindependent observations.

RESULTS

Among 1,903 participants (56% women, mean ± SD age 65 ± 9 years), 22% of knees were painful most days. Cartilage damage was identified in 45% of medial tibiofemoral (TF), 27% of lateral TF, 58% of medial patellofemoral (PF), and 42% of lateral PF compartments. Compared with other feet, the most planus feet had 1.3 times (95% confidence interval [95% CI] 1.1-1.6) the odds of knee pain (P = 0.009), and 1.4 times (95% CI 1.1-1.8) the odds of medial TF cartilage damage (P = 0.002). Odds of pain (P for linear trend = 0.05) and medial TF cartilage damage (P for linear trend = 0.001) increased linearly across categories of increasing SAI. There was no association between foot morphology and cartilage damage in other knee compartments.

CONCLUSION

Planus foot morphology is associated with frequent knee pain and medial TF cartilage damage in older adults.

Association between patella alta and the prevalence and worsening of structural features of patellofemoral joint osteoarthritis: the multicenter osteoarthritis study

OBJECTIVE

To examine the relationship between patella alta and the prevalence and worsening at followup of structural features of patellofemoral joint (PFJ) osteoarthritis (OA) on magnetic resonance imaging (MRI).

METHODS

The Multicenter Osteoarthritis Study is a cohort study of persons ages 50-79 years with or at risk for knee OA. Patella alta was measured using the Insall-Salvati ratio (ISR) on the baseline lateral radiograph, and cartilage damage, bone marrow lesions (BMLs), and subchondral bone attrition (SBA) were graded on MRI at baseline and at 30 months of followup in the PFJ. We examined the association of the ISR with the prevalence and worsening of cartilage damage, BMLs, and SBA in the PFJ using logistic regression.

RESULTS

A total of 907 knees were studied (mean age 62 years, body mass index 30 kg/m(2), ISR 1.10), 63% from female subjects. Compared with knees in the lowest ISR quartile at baseline, those in the highest quartile had 2.4 (95% confidence interval [95% CI] 1.7-3.3), 2.9 (95% CI 2.0-4.3), and 3.5 (95% CI 2.3-5.5) times the odds of having lateral PFJ cartilage damage, BMLs, and SBA, respectively, and 1.5 (95% CI 1.1-2.0), 1.3 (95% CI 0.9-1.8), and 2.2 (95% CI 1.4-3.4) times the odds of having medial PFJ cartilage damage, BMLs, and SBA, respectively. Similarly, those with high ISRs were also at risk for worsening of cartilage damage and BMLs over time than those with low ISRs.

CONCLUSION

A high ISR, indicative of patella alta, is associated with structural features of OA in the PFJ. Additionally, the same knees have an increased risk of worsening of these same features over time.

The effects of impaired joint position sense on the development and progression of pain and structural damage in knee osteoarthritis

OBJECTIVE

Although cross-sectional studies have reported impaired proprioceptive acuity in people with osteoarthritis (OA), there have been no longitudinal studies to evaluate whether those with such impairments increase the risk of OA or its worsening.

METHODS

We studied subjects from the Multicenter Osteoarthritis Study study, a longitudinal study of people with or at high risk of knee OA. At baseline, we quantified acuity as the amount of a subject's error when attempting to reproduce a test knee flexion angle (a measure of joint position sense). We tested proprioception 10 times in the right leg and used a person's worst score as their proprioceptive acuity. At baseline and the 30-month followup, we assessed the presence of frequent pain, obtained Western Ontario and McMasters Universities OA Index (WOMAC) scores, and acquired posteroanterior and lateral weight-bearing knee radiographs read for Kellgren/Lawrence grade and individual radiographic features. We examined the relation of baseline proprioceptive acuity in quartiles with baseline knee pain (frequent pain yes/no), WOMAC pain score, self-reported physical function, and radiographic OA, and with changes from baseline in pain, physical function, and radiographic OA adjusted for age, sex, body mass index, and quadriceps strength.

RESULTS

At baseline, proprioceptive acuity was associated with the presence and severity of knee pain but not with the presence of radiographic OA. However, among the 2,243 subjects with baseline acuity assessments and 30-month followup, there were no strong associations between proprioceptive acuity and development of adverse OA outcomes. Acuity was not significantly associated with the new onset of frequent knee pain. Those with the worst acuity at baseline had slightly greater worsening of WOMAC pain scores (0.47 on a 20-point scale) and physical function scores (by 1.5 points on a 0-68-point scale) compared with those with the best proprioceptive acuity, whose pain and physical function score deteriorated less (for pain P = 0.05; for physical function P = 0.02). Radiographic worsening was not significantly associated with proprioceptive acuity.

CONCLUSION

Proprioceptive acuity as assessed by the accuracy of reproduction of the angle of knee flexion had modest effects on the trajectory of pain and physical functional limitation in knee OA.

Knee osteoarthritis: primary care using noninvasive devices and biomechanical principles

Osteoarthritis (OA) is an epidemic for which there is no known cure. There is enormous popular demand for noninvasive and nonpharmacologic therapies for OA, and there is a pressing need for primary care physicians to respond by updating their pattern of practice. Despite increasing concern about the capacity of our health care system to meet rising demands, routine primary care for knee OA has changed little over several decades. This article introduces physicians to many of the most important noninvasive devices used in the conservative management of symptomatic knee OA.

Varus foot alignment and hip conditions in older adults

OBJECTIVE

Mechanical strain on the hip can result from varus malalignment of the foot. This study was undertaken to explore the cross-sectional relationship between varus foot alignment and hip conditions in a population of older adults.

METHODS

The Framingham Osteoarthritis Study cohort consists of a population-based sample of older adults. Within this sample, we measured forefoot and rearfoot frontal plane alignment using photographs of a non-weight-bearing view of both feet of 385 men and women (mean age 63.1 years). Each foot segment was categorized according to the distribution of forefoot and rearfoot alignment among cases of ipsilateral hip pain, trochanter tenderness, hip pain or tenderness, and total hip replacement (THR). The relationship of foot alignment to these conditions was examined using logistic regression and generalized estimating equations, adjusting for age, body mass index, sex, and physical activity.

RESULTS

The mean +/- SD rearfoot varus alignment was 0.7 +/- 5.5 degrees, and the mean +/- SD forefoot varus alignment was 9.9 +/- 9.9 degrees. Subjects in the highest category of forefoot varus alignment had 1.8 times the odds of having ipsilateral hip pain (P for trend = 0.06), 1.9 times the odds of having hip pain or tenderness (P for trend < 0.01), and 5.1 times the odds of having undergone THR (P for trend = 0.04) compared with those in the lowest category. No significant associations were found between rearfoot varus alignment and any hip conditions.

CONCLUSION

Forefoot varus malalignment may be associated with ipsilateral hip pain or tenderness and THR in older adults. These findings have implications for treatment, since this risk factor is potentially modifiable with foot orthoses.

Knee alignment does not predict incident osteoarthritis: the Framingham osteoarthritis study

OBJECTIVE

To examine the relationship of knee malalignment to the occurrence of knee osteoarthritis (OA) among subjects without radiographic OA at baseline to determine whether malalignment is a risk factor for incident disease or simply a marker of increasing disease severity.

METHODS

We selected 110 incident tibiofemoral (TF) OA case knees (76 subjects) and 356 random control knees (178 subjects) from among participants in the Framingham Osteoarthritis Study. Case knees did not have OA at baseline (1992-1994 examination) but had developed OA (Kellgren/Lawrence grade>or=2) at followup (2002-2005 examination) (mean of 8.75 years between examinations). Control knees did not have OA at baseline. Standardized digital radiographs of the fully extended knee with weight-bearing were read using a standard protocol and eFilm viewing software. We measured the anatomic axis, the condylar angle, the tibial plateau angle, and the condylar tibial plateau angle. The interobserver intraclass correlation coefficient (ICC) ranged from 0.93 to 0.96 and the intraobserver ICC from 0.94 to 0.97. In a knee-specific analysis, we examined the relationship of each alignment measurement to the risk of TF OA using generalized estimating equations, adjusting for age, sex, and body mass index (BMI). We used the same approach to assess the association between each alignment measurement and the risk of medial TF OA.

RESULTS

Subjects in the case population were older and had a higher BMI than the controls. The alignment values were normally distributed and were not different between the cases and the controls. After adjustment for age, sex and BMI, there was no significant increase in incident OA in the highest quartile compared with the lowest quartile category for any of the alignment measures (P for trend for anatomic axis and condylar tibial plateau angle was 0.83 and 0.80, respectively). Similar results were also observed for medial compartment OA.

CONCLUSION

We found that baseline knee alignment is not associated with either incident radiographic TF OA or medial TF OA. These results suggest that malalignment is not a risk factor for OA, but rather is a marker of disease severity and/or its progression.