Orit Almagor

The role of varus and valgus alignment in the initial development of knee cartilage damage by MRI: the MOST study

Objective Varus and valgus alignment are associated with progression of knee osteoarthritis, but their role in incident disease is less certain. Radiographic measures of incident knee osteoarthritis may be capturing early progression rather than disease development. The authors tested the hypothesis: in knees with normal cartilage morphology by MRI, varus is associated with incident medial cartilage damage and valgus with incident lateral damage. Methods In MOST, a prospective study of persons at risk of or with knee osteoarthritis, baseline full-limb x-rays and baseline and 30-month MRI were acquired. In knees with normal baseline cartilage morphology in all tibiofemoral subregions, logistic regression was used with generalised estimating equations to examine the association between alignment and incident cartilage damage adjusting for age, gender, body mass index, laxity, meniscal tear and extrusion. Results Of 1881 knees, 293 from 256 persons met the criteria. Varus versus non-varus was associated with incident medial damage (adjusted OR 3.59, 95% CI 1.59 to 8.10), as was varus versus neutral, with evidence of a dose effect (adjusted OR 1.38/1° varus, 95% CI 1.19 to 1.59). The findings held even excluding knees with medial meniscal damage. Valgus was not associated with incident lateral damage. Varus and valgus were associated with a reduced risk of incident lateral and medial damage, respectively. Conclusion In knees with normal cartilage morphology, varus was associated with incident cartilage damage in the medial compartment, and varus and valgus with a reduced risk of incident damage in the less loaded compartment. These results support that varus increases the risk of the initial development of knee osteoarthritis.

External knee adduction and flexion moments during gait and medial tibiofemoral disease progression in knee osteoarthritis

Objective Test the hypothesis that greater baseline peak external knee adduction moment (KAM), KAM impulse, and peak external knee flexion moment (KFM) during the stance phase of gait are associated with baseline-to-2-year medial tibiofemoral cartilage damage and bone marrow lesion progression, and cartilage thickness loss. Methods Participants all had knee OA in at least one knee. Baseline peak KAM, KAM impulse, and peak KFM (normalized to body weight and height) were captured and computed using a motion analysis system and 6 force plates. Participants underwent MRI of both knees at baseline and two years later. To assess the association between baseline moments and baseline-to-2-year semiquantitative cartilage damage and bone marrow lesion progression and quantitative cartilage thickness loss, we used logistic regression with generalized estimating equations (GEE), adjusting for gait speed, age, gender, disease severity, knee pain severity, and medication use. Results The sample consisted of 391 knees (204 persons): mean age 64.2 years (SD 10.0); BMI 28.4 kg/m2 (5.7); 156 (76.5%) women. Greater baseline peak KAM and KAM impulse were each associated with worsening of medial bone marrow lesions, but not cartilage damage. Higher baseline KAM impulse was associated with 2-year medial cartilage thickness loss assessed both as % loss and as a threshold of loss, whereas peak KAM was related only to % loss. There was no relationship between baseline peak KFM and any medial disease progression outcome measures. Conclusion Findings support targeting KAM parameters in an effort to delay medial OA disease progression.

Denuded Subchondral Bone and Knee Pain in Persons with Knee Osteoarthritis

OBJECTIVE It is unclear how articular cartilage loss contributes to pain in patients with knee osteoarthritis (OA). Full-thickness cartilage defects expose the subchondral bone plate. The relationship between denuded bone and pain has not been examined. The aim of this study was to investigate whether the percent of denuded bone is associated with moderate-to-severe knee pain or frequent knee pain and longitudinally with frequent knee pain 2 years after the baseline evaluation. METHODS We studied 182 persons with knee OA (305 knees). Applying specialized magnetic resonance imaging techniques, manual segmentation was used to compute cartilage-covered and denuded bone areas for each surface. Moderate-to-severe knee pain was defined as a score of >or=40 mm on a knee-specific 100-mm visual analog scale, and frequent knee pain was defined as pain on most days during the past month. Logistic regression and generalized estimating equations were used in analyses, adjusting for age, sex, body mass index, and bone marrow lesions. RESULTS Cross-sectional analyses revealed that moderate-to-severe knee pain was associated with percent denuded bone in the medial compartment (adjusted odds ratio [OR] 3.90, 95% confidence interval [95% CI] 1.33-11.47), in the medial and patellar surfaces together, and in the lateral and patellar surfaces. Frequent knee pain was associated with percent denuded bone in the patellar surface (adjusted OR 3.11, 95% CI 1.24-7.81), in the medial and patellar surfaces, and in the lateral and patellar surfaces. Longitudinal analyses (in 168 knees without frequent knee pain at baseline) revealed that percent denuded bone in the medial and patellar surfaces was associated with frequent incident knee pain (adjusted OR 4.19, 95% CI 1.56-11.22). CONCLUSION These results support a relationship between subchondral bone plate exposure and prevalent and incident knee pain in patients with knee OA.

A Comparison of Discharge Functional Status After Rehabilitation in Skilled Nursing, Home Health, and Medical Rehabilitation Settings for Patients After Lower-Extremity Joint Replacement Surgery

OBJECTIVE To examine differences in outcomes of patients after lower-extremity joint replacement across 3 post-acute care (PAC) rehabilitation settings. DESIGN Prospective observational cohort study. SETTING Skilled nursing facilities (SNFs; n=5), inpatient rehabilitation facilities (IRFs; n=4), and home health agencies (HHAs; n=6) from 11 states. PARTICIPANTS Patients with total knee (n=146) or total hip replacement (n=84) not related to traumatic injury. INTERVENTIONS None. MAIN OUTCOME MEASURE Self-care and mobility status at PAC discharge measured by using the Inpatient Rehabilitation Facility Patient Assessment Instrument. RESULTS Based on our study sample, HHA patients were significantly less dependent than SNF and IRF patients at admission and discharge in self-care and mobility. IRF and SNF patients had similar mobility levels at admission and discharge and similar self-care at admission, but SNF patients were more independent in self-care at discharge. After controlling for differences in patient severity and length of stay in multivariate analyses, HHA setting was not a significant predictor of self-care discharge status, suggesting that HHA patients were less medically complex than SNF and IRF patients. IRF patients were more dependent in discharge self-care even after controlling for severity. For the full discharge mobility regression model, urinary incontinence was the only significant covariate. CONCLUSIONS For the patients in our U.S.-based study, direct discharge to home with home care was the optimal strategy for patients after total joint replacement surgery who were healthy and had social support. For sicker patients, availability of 24-hour medical and nursing care may be needed, but intensive therapy services did not seem to provide additional improvement in functional recovery in these patients.

Significance of Preradiographic Magnetic Resonance Imaging Lesions in Persons at Increased Risk of Knee Osteoarthritis

Little is known about early knee osteoarthritis (OA). The significance of lesions on magnetic resonance imaging (MRI) in older persons without radiographic OA is unclear. Our objectives were to determine the extent of tissue pathology by MRI and evaluate its significance by testing the following hypotheses: cartilage damage, bone marrow lesions, and meniscal damage are associated with prevalent frequent knee symptoms and incident persistent symptoms; bone marrow lesions and meniscal damage are associated with incident tibiofemoral (TF) cartilage damage; and bone marrow lesions are associated with incident patellofemoral (PF) cartilage damage.

Within-Subregion Relationship Between Bone Marrow Lesions and Subsequent Cartilage Loss in Knee Osteoarthritis

Bone marrow lesions are believed to increase risk of knee osteoarthritis (OA) progression. Whether their effect is local and whether it can be explained by other types of bone lesions concomitantly present in the same subregion is unclear. We evaluated bone lesion frequency in subregions without cartilage lesions and cartilage lesion frequency in subregions without bone lesions, and investigated the within‐subregion bone marrow lesion/subsequent cartilage loss relationship after adjusting for other types of bone lesions at baseline.

Subregional effects of meniscal tears on cartilage loss over 2 years in knee osteoarthritis

Objectives Meniscal tears have been linked to knee osteoarthritis progression, presumably by impaired load attenuation. How meniscal tears affect osteoarthritis is unclear; subregional examination may help to elucidate whether the impact is local. This study examined the association between a tear within a specific meniscal segment and subsequent 2-year cartilage loss in subregions that the torn segment overlies. Methods Participants with knee osteoarthritis underwent bilateral knee MRI at baseline and 2 years. Mean cartilage thickness within each subregion was quantified. Logistic regression with generalised estimating equations were used to analyse the relationship between baseline meniscal tear in each segment and baseline to 2-year cartilage loss in each subregion, adjusting for age, gender, body mass index, tear in the other two segments and extrusion. Results 261 knees were studied in 159 individuals. Medial meniscal body tear was associated with cartilage loss in external subregions and in central and anterior tibial subregions, and posterior horn tear specifically with posterior tibial subregion loss; these relationships were independent of tears in the other segments and persisted in tibial subregions after adjustment for extrusion. Lateral meniscal body and posterior horn tear were also associated with cartilage loss in underlying subregions but not after adjustment for extrusion. Cartilage loss in the internal subregions, not covered by the menisci, was not associated with meniscal tear in any segment. Conclusion These results suggest that the detrimental effect of meniscal tears is not spatially uniform across the tibial and femoral cartilage surfaces and that some of the effect is experienced locally.

Comparison of two home care protocols for total joint replacement.

OBJECTIVES: To examine the effect of a more‐efficient home care protocol to manage total joint replacement (TJR) patients after surgery.

Varus-valgus alignment: reduced risk of subsequent cartilage loss in the less loaded compartment.

OBJECTIVE Varus-valgus alignment has been linked to subsequent progression of osteoarthritis (OA) within the mechanically stressed (medial for varus, lateral for valgus) tibiofemoral compartment. Cartilage data from the off-loaded compartment are sparse. The purpose of this study was to examine our hypotheses that neutral and valgus (versus varus) knees each have reduced odds of cartilage loss in the medial subregions and that neutral and varus (versus valgus) knees each have reduced odds of cartilage loss in the lateral subregions. METHODS Patients with knee OA underwent knee magnetic resonance imaging at baseline and 2 years. The mean cartilage thickness was quantified within 5 tibial and 3 femoral subregions. We used logistic regression with generalized estimating equations to analyze the relationship between baseline alignment and subregional cartilage loss at 2 years, adjusting for age, sex, body mass index, and disease severity. RESULTS A reduced risk of cartilage loss in the medial subregions was associated with neutral (versus varus) alignment (external tibial, central femoral, external femoral) and with valgus (versus varus) alignment (central tibial, external tibial, central femoral, external femoral). A reduced risk of cartilage loss in the lateral subregions was associated with neutral (versus valgus) alignment (central tibial, internal tibial, posterior tibial) and with varus (versus valgus) alignment (central tibial, external tibial, posterior tibial, external femoral). CONCLUSION Neutral and valgus alignment were each associated with a reduction in the risk of subsequent cartilage loss in certain medial subregions and neutral and varus alignment with a reduction in the risk of cartilage loss in certain lateral subregions. These results support load redistribution as an in vivo mechanism of the long-term alignment effects on cartilage loss in knee OA.

Comparison of Discharge Functional Status After Rehabilitation in Skilled Nursing, Home Health, and Medical Rehabilitation Settings for Patients After Hip Fracture Repair

OBJECTIVE To examine differences in rehabilitation outcomes across 3 post-acute care (PAC) rehabilitation settings for patients after hip fracture repair. DESIGN Prospective, observational cohort study. SETTING Six skilled nursing facilities (SNFs), 4 inpatient rehabilitation facilities (IRFs), and 8 home health agencies (HHAs) in 10 states. PARTICIPANTS Patients (N=181) receiving PAC rehabilitation following hip fracture with internal fixation (n=116) or total hip replacement (n=64), or no surgical intervention (n=1). INTERVENTIONS Not applicable. MAIN OUTCOME MEASURE Self-care and mobility status at PAC discharge measured by the Inpatient Rehabilitation Facility Patient Assessment Instrument. RESULTS IRF and HHA patients had lower self-care function at discharge relative to SNF patients controlling for patient characteristics, severity, comorbidities, and services. Adding length of stay (LOS) resulted in nonsignificant differences between IRFs and SNFs. In contrast, there was no setting-specific advantage in discharge mobility for patients with or without the addition of LOS. The average LOS of HHA patients was 2 weeks longer than that of SNF patients, whose average LOS was 9 days longer than that of IRF patients (average, 15d). IRF and SNF patients received about the same total minutes of therapy over their PAC stays (∼2100min on average), whereas HHA patients received only approximately 25% as many minutes. CONCLUSIONS Setting-specific effects varied depending on whether self-care or mobility was the outcome of focus. It remains unclear to what extent rehabilitation intensity or natural recovery effects changes in functional status for patients with hip fracture. This study points to important directions for PAC setting comparative effectiveness studies in the future, including uniform measurement, limited consensus on factors affecting recovery, accounting for selection bias, and using end-point data collection that is at the same follow-up time periods for all settings.