Is increased joint loading detrimental to obese patients with knee osteoarthritis? A secondary data analysis from a randomized trial.

OBJECTIVE: To investigate whether increased knee joint loading due to improved ambulatory function and walking speed following weight loss achieved over 16 weeks accelerates symptomatic and structural disease progression over a subsequent 1 year weight maintenance period in an obese population with knee osteoarthritis (OA). METHODS: Data from a prospective study of weight loss in obese patients with knee OA (the CARtilage in obese knee OsteoarThritis (CAROT) study) were used to determine changes in knee joint compressive loadings (model estimated) during walking after a successful 16 week weight loss intervention. The participants were divided into 'Unloaders' (participants that reduced joint loads) and 'Loaders' (participants that increased joint loads). The primary symptomatic outcome was changes in knee symptoms, measured with the Knee injury and Osteoarthritis Outcome Score (KOOS) questionnaire, during a subsequent 52 weeks weight maintenance period. The primary structural outcome was changes in tibiofemoral cartilage loss assessed semi-quantitatively (Boston Leeds Knee Osteoarthritis Score (BLOKS) from MRI after the 52 weight maintenance period. RESULTS: 157 participants (82% of the CAROT cohort) with medial and/or lateral knee OA were classified as Unloaders (n = 100) or Loaders (n = 57). The groups showed similar significant changes in symptoms (group difference: -2.4 KOOS points [95% CI -6.8:1.9]) and cartilage loss (group difference: -0.06 BLOKS points [95% CI -0.22:0.11) after 1 year, with no statistically significant differences between Loaders and Unloaders. CONCLUSION: For obese patients undergoing a significant weight loss, increased knee joint loading for 1 year was not associated with accelerated symptomatic and structural disease progression compared to a similar weight loss group that had reduced ambulatory compressive knee joint loads. CLINICALTRIALSGOV: NCT00655941.

Weight loss is effective for symptomatic relief in obese subjects with knee osteoarthritis independently of joint damage severity assessed by high-field MRI and radiography.

OBJECTIVE: With an increasing prevalence of older and obese citizens, the problems of knee osteoarthritis (KOA) will escalate. Weight loss is recommended for obese KOA patients and in a majority of cases this leads to symptomatic relief. We hypothesized that pre-treatment structural status of the knee joint, assessed by radiographs, 1.5 T magnetic resonance imaging (MRI) and knee-joint alignment, may influence the symptomatic changes following a significant weight reduction. DESIGN: Patients were recruited from a Department of Rheumatology. Eligibility criteria were age above 50 years, body mass index ≥ 30 kg/m(2), primary KOA diagnosed according to the American College of Rheumatology (ACR) criteria and having verified structural damage. Patients underwent a 16 weeks dietary programme with formula products and counselling. MRI and radiographs of the most symptomatic knee were obtained at baseline and assessed for structural damage using the Boston-Leeds Osteoarthritis of the Knee Score, minimum joint space width and Kellgren-Lawrence score. Imaging variables, muscle strength and degree of alignment, were examined as predictors of changes in Knee Osteoarthritis Outcome Score (KOOS) and Outcome Measures in Rheumatoid Arthritis Clinical Trials (OMERACT) - Osteoarthritis Research Society International (OARSI) Responder Criterion. RESULTS: Structural damage at baseline assessed by imaging, muscle strength or knee-joint alignment showed no statistically significant association to changes in KOOS pain and function in daily living (r ≤ 0.13; P>0.05) or the OMERACT-OARSI Responder Criterion (OR 0.48-1.68; P-values ≥ 0.13). CONCLUSIONS: Presence of joint damage did not preclude symptomatic relief following a clinically relevant weight loss in older obese patients with KOA. Neither muscle strength nor knee-joint alignment was associated with the degree of symptomatic relief.

Adaptations in the gait pattern with experimental hamstring pain.

Pain changes movement but most studies have focused on basic physiological adaptations during non-functional movement tasks. The existing studies on how pain affects lower extremity gross movement biomechanics have primarily involved movements in which the quadriceps is the primary muscle and little attention has been given to how pain in other muscles affects functional movement. The purpose of this study was to investigate the changes in the gait patterns of healthy subjects that occur during experimental muscle pain in the biceps femoris. In a cross-over study design, 14 healthy volunteers underwent EMG assisted 3D gait analyses before, during and after experimental biceps femoris pain induced by intramuscular injections of hypertonic saline. Isotonic saline injections were administered as a non-painful control. The experimental biceps femoris pain led to reductions in hip extensor moments, knee flexor and lateral rotator moments. No changes in lower extremity kinematics and EMG activity in any of the recorded muscles were observed. It is concluded that experimental muscle pain in the biceps femoris leads to changes in the gait pattern in agreement with unloading of the painful muscle. The changes are specific to the painful muscle. The present study provides support to the theory that musculoskeletal pain is a protective signal leading to changes in movement patterns that serve to unload the painful tissue.

Effects of an intensive weight loss program on knee joint loading in obese adults with knee osteoarthritis.

OBJECTIVE: To determine the effect of an intensive weight loss program on knee joint loads during walking in obese patients with knee osteoarthritis (OA). METHODS: Participants included 157 obese knee OA patients that underwent a 16-week dietary intervention. Three-dimensional gait analyses were performed before and after the intervention at the participants' freely chosen walking speed. Knee joint compression forces, axial impulses, knee flexion angle and frontal and sagittal plane knee moments were calculated to determine the biomechanical effects of the weight loss. RESULTS: 157 subjects (89% of the initial cohort) completed the 16-week intervention. The average weight loss of 13.7 kg (P<.0001) corresponded to 13.5% of the baseline body weight. The weight loss resulted in a 7% reduction in knee joint loading, a 13% lower axial impulse, and a 12% reduction in the internal knee abductor moment (KAM). There were no clear effects on sagittal plane knee moments or peak knee flexion angle. Linear regression analyses adjusted for changes in walking speed showed that for every 1 kg in weight loss, the peak knee load was reduced by 2.2 kg. Thus, every kilo reduction in body weight was related to more than twice the reduction in peak knee force at a given walking speed. CONCLUSION: Weight loss is an excellent short-term investment in terms of joint loading for patients with combined obesity and knee OA. The effects of sustained weight loss on disease progression and symptoms in relation to biomechanical factors remain to be shown.

Is it possible to reduce the knee joint compression force during level walking with hiking poles?

Walking with hiking poles has become a popular way of exercising. Walking with poles is advocated as a physical activity that significantly reduces the loading of the hip, knee and ankle joints. We have previously observed that pole walking does not lead to a reduction of the load on the knee joint. However, it is unclear whether an increased force transmitted through the poles can reduce the load on the knee joint. Thus, the purpose of the present study was to investigate if an increased load transmitted through the arms to the poles could reduce the knee joint compression force during level walking with poles. We hypothesized that an increased pole force would result in a reduction of the knee joint compression force. Gait analyses from 10 healthy subjects walking with poles were obtained. The pole force was measured simultaneously during the gait analyses. The knee joint compression forces were estimated by using a biomechanical knee joint model. The results showed that the subjects were able to increase the pole force by 2.4 times the normal pole force. However, this did not lead to a reduction in the knee joint compressive force and we rejected our hypothesis. In conclusion, the use of poles during level walking does not seem to reduce knee joint compressive loads. However, it is possible that the use of poles in other populations (e.g. osteoarthritis patients) and in terrain would unload the knee joint. This should be investigated in the future.

Osteoarthritis - a role for weight management in rheumatology practice: an update.

Osteoarthritis (OA) and obesity are related diseases, which occur in a large proportion of the population. Epidemiological evidence show that weight is of great importance for the development of OA in the knee, and to some extent also in hip and finger joints. Once acquired, the OA contributes to further weight problems by decreasing the daily activity level. Weight loss will be beneficial for the knee and experimental data point at a highly significant effect on knee function and recent results even point at a positive effect on the cartilage of the knee joint. Recommending patients with a combination of knee OA and obesity to lose at least 5% body weight, and aim for 10% is predicted to correspond to 26% improvement in physical function. A programme for this weight loss has been tested with good results applying an initial formula diet with maintenance therapy in groups during follow-up.

Effect of whole body vibration exercise on muscle strength and proprioception in females with knee osteoarthritis.

The purpose of this study was to assess the effect of whole body vibration (WBV) exercise on muscle strength and proprioception in female patients with osteoarthritis in the knee (knee-OA). A single blinded, randomised, controlled trial was performed in an outpatient clinic on 52 female patients diagnosed with knee-OA (mean age 60.4 years+/-9.6). They were randomly assigned to one of 3 groups: 1. WBV-exercise on a stable platform (VibM; n=17 (mean age, 61.5+/-9.2)), WBV-exercise on a balance board (VibF; n=18 (mean age, 58.7+/-11.0)), or control group (Con; n=18 (mean age, 61.1+/-8.5)). The WBV groups trained twice a week for 8 weeks, with a progressively increasing intensity. The WBV groups performed unloaded static WBV exercise. The following were measured: knee muscle strength (extension/flexion) and proprioception (threshold for detection of passive movement (TDPM)). Self-reported disease status was measured using WOMAC. It was found that muscle strength increased significantly (p<0.001) in VibM compared to Con. Isometric knee-extension significantly increased (p=0.021) in VibM compared to Con. TDPM was significantly improved (p=0.033) in VibF compared to Con, while there was a tendency (p=0.051) for VibM to perform better compared to Con. There were no effects in the self-reported disease status measures. This study showed that the WBV-exercise regime on a stable platform (VibM) yielded increased muscle strength, while the WBV-exercise on a balance board (VibF) showed improved TDPM. The WBV-exercise is a time-saving and safe method for rehabilitation of women with knee-OA.