K. Douglas Gross

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.

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 subjects 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 persons 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.

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.

Association between measures of trochlear morphology and structural features of patellofemoral joint osteoarthritis on MRI: the MOST study.

The sulcus angle has been widely used in the literature as a measure of trochlear morphology. Recently, lateral trochlear inclination and trochlear angle have been reported as alternatives. The purpose of this study was to determine the association between measures of trochlear morphology and patellofemoral joint (PFJ) cartilage damage and bone marrow lesions (BMLs). Nine hundred seven knees were selected from the Multicenter Osteoarthritis Study, a cohort study of persons aged 50–79 years with or at risk for knee OA. Trochlear morphology was measured using lateral trochlear inclination, trochlear angle, and sulcus angle on axial MRI images; cartilage damage and BMLs were graded on MRI. We determined the association between quartiles of each trochlear morphology variable with the presence or absence of cartilage damage and BMLs in the PFJ using logistic regression. The strongest associations were seen with lateral trochlear inclination and lateral PFJ cartilage damage and BMLs, with knees in the lowest quartile (flattened lateral trochlea) having more than two times the odds of lateral cartilage damage and BMLs compared to those in the highest quartile (p < 0.0001). Lateral trochlear inclination may be the best method for assessment of trochlear morphology as it was strongly association with structural damage in the PFJ.

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

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.

Noninvasive Devices Targeting the Mechanics of Osteoarthritis

The goal of many noninvasive devices for knee osteoarthritis (OA) is to alter joint biomechanics and thereby limit regional exposure to damaging and provocative mechanical stresses. Optimal prescription of most noninvasive devices first requires the specification of which mechanical stresses should be reduced, and in which knee region. This article introduces several types of devices currently used in the treatment of knee OA. Each section begins with a short presentation of the devices biomechanical effects and considers evidence of clinical efficacy. Where possible, the authors conclude each section by offering their subjective insights and clinical impressions.

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

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.

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.

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.

Device use: walking AIDS, braces, and orthoses for symptomatic knee osteoarthritis.

With too few conservative options in the current medical system, increasing numbers of osteoarthritis (OA) sufferers are using untested folk remedies and self-prescribed dietary supplements. There is enormous popular demand for noninvasive and nonpharmacologic therapies for OA, and there is a pressing need for clinicians to respond to this demand by updating their practice. This review introduces clinicians to the most important noninvasive devices used in the conservative management of knee OA. Because the shared goal of these devices is to favorably alter lower limb biomechanics, each section of the review considers evidence of biomechanical and clinical efficacy.