Physical therapy for osteoarthritis

Physiotherapy for osteoarthritis helps to:

• prevention or elimination of atrophy of periarticular muscles (for example, the quadriceps muscle of the thigh in patients with gonarthrosis ),
• prevention or elimination of joint instability,
• reduction of arthralgia, improvement of the function of affected joints,
• slowing down the further progression of osteoarthritis,
• reduction of body weight.

Exercises to increase range of motion

The causes of joint stiffness in patients with osteoarthritis may be:

• distension of the joint capsule secondary to an increase in the volume of synovial fluid,
• retraction of the joint capsule, periarticular ligaments and tendons,
• fibrous ankylosis of the joint of varying severity due to loss of articular cartilage,
• incongruence of articular surfaces, presence of mechanical block (osteophytes, joint "mice"),
• muscle spasm,
• joint pain.

In addition, the attending physician should take into account that a decrease in the range of motion in one joint affects the biomechanics of adjacent distal and proximal joints. For example, according to S. Messier et al. (1992) and D. Jesevar et al. (1993), in elderly patients with gonarthrosis, the range of motion was reduced in all large joints of both lower limbs (hip, knee, and ankle) compared to individuals in the control group without joint diseases. Impaired biomechanics of the affected joint leads to changes in normal limb movements, increases the load on the joints, increases energy consumption during movement, and increases pain and joint instability. Moreover, limiting the range of motion of the lower limb joints changes the normal kinematics of gait. For example, a patient with gonarthrosis has reduced angular velocity and range of motion of the knee joint, but a compensatory increase in the angular velocity of the hip joint compared to individuals in the control group, matched by age, gender and body weight, without osteoarthrosis. In addition, patients with gonarthrosis have an increased load on the unaffected limb. Currently, it is generally accepted that long-term passive movements have a trophic effect on articular cartilage and can promote its reparation. Therefore, restoration of the functional range of motion in the affected joints is an important task of non-drug treatment and rehabilitation of patients with osteoarthrosis.

Currently, various physical exercises are used to restore the range of motion in joints:

• passive (the joint is mobilized by the therapist or his assistant),
• semi-active (the patient independently performs movements in the joint, the methodologist/assistant helps only at the end of each movement to achieve the maximum volume),
• active (the patient independently performs movements to the fullest extent possible).

Before the exercise complex, massage or physiotherapy (infrared, short-wave, microwave radiation, ultrasound) can be performed to reduce stiffness in the affected joints and make it easier to perform the exercises.

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Exercises to strengthen the periarticular muscles

There are many reports in the literature on the relationship between knee osteoarthritis and weakness/hypertrophy of the quadriceps femoris. The results of these studies indicate that in patients with gonarthrosis, joint pain may be a consequence of weakness of the periarticular muscles and their asymmetric activity, which leads to joint destabilization. Loading of the unstable joint causes stretching of the innervated tissues and provokes pain, which inhibits the reflex activity of skeletal muscles, thereby limiting the function of the limb; thus, a “vicious circle” is closed. In patients with manifest osteoarthritis of the knee joint, weakness of the quadriceps femoris is often observed, the direct cause of which is pain, limiting voluntary movements in the joint, which leads to the development of atrophy of the periarticular muscles. This phenomenon is called “arthrogenic muscle inhibition” (AMI). P. Geborek et al. (1989) reported on inhibition of muscle function in normal and osteoarthrosis-affected knee joints with an increase in the volume of intra-articular fluid and an increase in hydrostatic pressure. Another study found that the maximum isometric strength of periarticular muscles is significantly reduced in the presence of effusion, and aspiration of excess fluid leads to its increase. At the same time, AUM is observed in patients without pain and joint effusion, which indicates the presence of other mechanisms of its development. According to a histochemical study, a decrease in the relative number of type II fibrils and the diameter of types I and II fibrils in the gluteus medius muscle of patients with severe coxarthrosis awaiting surgery (arthroplasty) compared to individuals in the control group. A relative increase in the number of type I fibrils may cause muscle stiffness and contribute to the development of osteoarthrosis. It should be noted that some patients without hypotrophy of the quadriceps muscle of the thigh may have weakness of this muscle. This observation indicates that muscle weakness is not always due to periarticular muscle atrophy or arthralgia and the presence of joint effusion, but more often to muscle dysfunction. The latter may be caused by limb deformity, muscle fatigue, or changes in proprioceptors. Electromyographic analysis of the quadriceps muscle of the thigh during isometric contraction with knee flexion at 30° and 60° showed significantly greater activity (mainly the rectus femoris) in patients with varus deformity of the knee joint than in healthy individuals. These data explain the higher energy requirement and rapid fatigue of patients with osteoarthritis during prolonged motor activity.

According to some researchers, weakness of the quadriceps muscle of the thigh is the primary risk factor for the progression of osteoarthritis of the knee joints. According to O. Madsen et al. (1997), a small increase in muscle strength (by 19% of the average in men and by 27% in women) can lead to a decrease in the risk of osteoarthritis progression by 20-30%.

The study involved quantitatively assessing the movements of the knee extensor and flexor in patients with gonarthrosis: both isometric and isotonic contraction of the quadriceps femoris was less pronounced in patients with knee osteoarthritis than in healthy volunteers. According to L. Nordersjo et al. (1983), the activity of the knee flexor contraction was also lower than normal, but to a lesser extent than the extensor. An isokinetic study found that in patients with gonarthrosis, weakness of the knee extensor is more common than weakness of the flexor.

Being natural shock absorbers, periarticular muscles perform a protective function. Despite the fact that a number of clinical studies have demonstrated the effect of exercises to strengthen the quadriceps femoris on the symptoms of osteoarthritis in patients with gonarthrosis, before starting their implementation, it is necessary to relieve pain, swelling of soft tissues, remove joint effusion in order to maximally eliminate the AUM phenomenon, which prevents effective rehabilitation. Moreover, the pressure generated by the activity of the flexor muscle in the knee joint with effusion affects the microcirculation of the synovial fluid by squeezing the capillaries.

Exercises for strengthening periarticular muscles can be divided into three groups:

• isometric (muscle contraction without changing its length): muscle contraction lasts 6 s, then relaxation follows, the exercise is repeated 5-10 times; coactivation of antagonist muscles is recommended in parallel. S. Himeno et al. (1986) found that the load is distributed equally on the surface of the TFO of the knee joint if the force of the agonist muscles is balanced by the force of the antagonist muscles, which in turn reduces the overall load on the joint surface and prevents local damage;
• isotonic (movements of the limb in the joint with or without additional resistance, in which the periarticular muscles are shortened or lengthened); isotonic exercises should be performed without overcoming the existing range of motion and with submaximal resistance;
• isokinetic (joint movements are performed in full volume at a constant speed); with the help of an isokinetic dynamometer, the resistance is varied in such a way that an increase in muscle strength contributes to an increase in resistance, and not to an increase in the speed of movement, and vice versa.

O. Miltner et al. (1997) reported on the effect of isokinetic exercise on the partial pressure of oxygen (pO ₂ ) in intra-articular tissues in patients with osteoarthrosis: a rate of 60° in 1 s led to a decrease in intra-articular pO ₂ below the level observed at rest, while a rate of 180° in 1 s caused an improvement in metabolism in intra-articular structures. It is known that a pathological decrease in intra-articular pO ₂ has destructive consequences for chondrocyte metabolism. However, the most dangerous is tissue reoxygenation that occurs following hypoxia. The results of a study by D. Blake et al. (1989) indicate that in cases of knee joint damage (arthritis of various etiologies, including osteoarthrosis, complicated synovitis), physical exercise induces damage mediated by active oxygen radicals. The mechanism of synovial ischemia-reperfusion is currently well known. In gonarthrosis, the average value of pO ₂ at rest is significantly reduced. Physical exercises in the knee joint with synovitis lead to a marked increase in intra-articular pressure, excess capillary perfusion pressure, and in some cases to an increase in systolic blood pressure, which causes tissue hypoxia. During this period of increased intra-articular pressure, pO ₂ of the synovial fluid decreases. At rest, intra-articular pressure decreases, and reperfusion occurs. The dominant sources of oxygen radicals in the joint affected by osteoarthrosis, formed as a result of the hypoxia-reoxygenation phenomenon, are capillary endothelial cells and chondrocytes. Oxygen radicals induce damage to all components of the cartilage matrix and reduce the viscosity of the synovial fluid. Moreover, hypoxia induces the synthesis and release of IL-1, a cytokine responsible for the degradation of articular cartilage, by endothelial cells.

The purpose of stretching exercises is to restore the length of shortened periarticular muscles. The causes of muscle shortening may be long-term muscle spasm, skeletal deformation, and limited joint motion. In turn, shortening of the periarticular muscles induces a limitation of the range of motion in the joint. After 4 weeks of stretching exercises and isometric exercises, J. Falconer et al. (1992) observed an increase in the range of motion and restoration of gait in patients with osteoarthrosis. G. Leivseth et al. (1988) studied the effectiveness of passive stretching of the abductor muscle of the thigh in 6 patients with coxarthrosis. Alternating stretching (30 sec) and pauses (10 sec) were repeated for 25 min 5 days a week for 4 weeks, which led to an increase in the range of hip abduction by an average of 8.3° and a decrease in the severity of joint pain. Muscle tissue biopsy revealed hypertrophy of type I and II fibrils and increased glycogen content.

Stretching exercises are contraindicated in the presence of joint effusion.

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Aerobic exercise

There is some evidence of the need for aerobic exercise programs in osteoarthrosis. It is known that oxygen and energy consumption during walking in patients with osteoarthrosis of the knee joints is increased. This is probably due to a change in the normal function of the joints and muscles, which leads to ineffective locomotion. Patients with gonarthrosis are often overweight and have weakness of the periarticular muscles. M. Ries et al. (1995) noted that the severity of gonarthrosis is associated with low maximum oxygen consumption (V ₀ max). This indicates detraining of the cardiovascular system in patients with severe gonarthrosis due to physical inactivity associated with severe pain syndrome and limitation of the function of the affected limb. The results of relatively recent studies have demonstrated an improvement in the physical ability of patients with osteoarthrosis (shortening the time to walk a certain distance, etc.) who participated in therapeutic aerobic exercise programs.

When developing individual aerobic exercise programs, it is necessary to consider which joint groups are affected by osteoarthritis. For example, cycling (bicycle ergometry) can be recommended to patients with gonarthrosis with a normal range of flexion in the knee joint and in the absence of significant changes in the PFO of the joint. Swimming and water exercises effectively reduce the load of body weight on the joints of the lower extremities in coxarthrosis and gonarthrosis.

However, a physical therapy specialist should take into account that excessive loads contribute to the development and progression of osteoarthrosis. Although, according to W. Rejeski et al. (1997), high-intensity aerobic exercises are more effective in improving the symptoms of osteoarthrosis than moderate and low-intensity exercises. In any case, when formulating recommendations for the patient, it is necessary to adhere to the basic principle - training should be no more than 3 times a week and last no more than 35-40 minutes.

According to a randomized comparative study of the effectiveness of aerobic exercise and an educational program in elderly patients with gonarthrosis, a more significant improvement in motor function and a decrease in pain were noted in the fitness group compared to the group of patients who participated only in the educational program. In another study, it was found that patients with osteoarthritis who participated only in aerobic training (aerobic walking, exercises in water) for 12 weeks, observed a more pronounced increase in aerobic capacity, an increase in walking speed, a decrease in anxiety / depression compared to a control group of patients who performed only passive exercises to restore the range of motion.

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