Can osteoarthritis cause weakness in the affected joint? 

Introduction 

Joint weakness is a significant and frequent symptom of osteoarthritis that often impacts daily life as much as pain or stiffness. While the condition primarily involves the breakdown of protective cartilage, it profoundly affects the surrounding muscles that are responsible for moving and stabilising the limb. This weakness is rarely a result of damage to the muscles themselves; rather, it is typically a secondary consequence of the body’s attempt to protect a painful joint. When a joint becomes uncomfortable, the brain may subconsciously reduce the signals sent to the nearby muscles, a process known as arthrogenic muscle inhibition, to prevent further irritation. Over time, this lack of full activation, combined with reduced physical activity to avoid pain, leads to muscle thinning and a noticeable loss of strength. Recognising that joint weakness is a biological and mechanical response to osteoarthritis is the first step toward effective management. By focusing on targeted, low-impact strengthening exercises, individuals can restore the supporting structures around the joint, which in turn reduces the overall load on the vulnerable cartilage and improves daily function. 

What We’ll Discuss in This Article 

• The clinical link between joint pain and muscle weakness 

• Understanding arthrogenic muscle inhibition and the brain-joint connection 

• How reduced activity leads to muscle atrophy and loss of stability 

• The impact of joint weakness on balance and the risk of falls 

• Why certain joints like the knee and hip are most prone to weakness 

• Identifying common triggers that exacerbate the feeling of joint instability 

• The importance of differentiating osteoarthritis weakness from neurological conditions 

The brain and muscle inhibition 

One of the most complex reasons for joint weakness in osteoarthritis is a phenomenon called arthrogenic muscle inhibition. When a joint is damaged, swollen, or painful, the sensory nerves within the joint capsule send signals to the central nervous system.³ In response, the brain automatically limits the electrical signals it sends to the muscles surrounding that specific joint. This is a protective reflex designed to prevent you from putting too much force through a joint that the body perceives as injured. 

For example, in individuals with knee osteoarthritis, the brain often inhibits the quadriceps muscles at the front of the thigh. Even if you try to contract the muscle forcefully, it may feel as though the strength simply isn’t there. This inhibition happens long before any actual muscle wasting occurs and is often one of the first signs of joint dysfunction. The NHS explains that this feeling of ‘giving way’ or ‘buckling’ is a direct result of this reduced muscle control and is a major contributor to the sense of instability. 

Muscle atrophy and reduced activity 

Beyond the brain’s inhibitory signals, physical weakness often develops because of disuse. When a joint is painful, it is natural to move it less or to change the way you walk to avoid discomfort. This reduction in the intensity and frequency of movement means the muscles are no longer being challenged. Over several months, this leads to muscle atrophy, where the muscle fibres shrink in size and strength. 

In the hip and knee, this atrophy can be quite visible; you may notice that one thigh looks slightly thinner than the other. This loss of muscle bulk is a significant issue because the muscles act as the joint’s primary shock absorbers. When the muscles are weak, the joint itself must take a much higher percentage of the impact from walking or climbing stairs. This extra pressure can speed up the thinning of cartilage, creating a cycle where pain leads to weakness, and weakness leads to more pain. 

Impact on balance and stability 

Joint weakness significantly affects a person’s sense of balance and proprioception, the body’s ability to sense its position in space. The muscles and tendons around a joint are filled with sensors that tell the brain exactly where the limb is. When osteoarthritis causes inflammation and muscle weakness, these sensors become less accurate. 

This loss of stability is particularly noticeable in weight-bearing joints: 

• The Knees: Weakness in the quadriceps can make the knee feel unstable when walking on uneven ground or descending stairs. 

• The Hips: Weakness in the gluteal muscles can cause the pelvis to tilt, affecting the entire gait and increasing the energy required to walk. 

• The Ankles: Reduced strength can make it harder for the joint to react to small slips, increasing the risk of a fall. 

Clinical guidance from NICE emphasises that strengthening these supporting muscles is one of the most effective non-surgical treatments for improving balance and safety. 

Weakness in the hands and grip strength 

While much focus is placed on the legs, osteoarthritis in the hands also causes significant weakness. This usually manifests as a reduced grip strength or difficulty with fine motor tasks. The base of the thumb is a common site for this, as the surrounding muscles may weaken due to the pain of ‘pinching’ or ‘twisting’ movements. 

This weakness can make it difficult to open jars, turn keys, or hold heavy objects. Because the hand is such a complex tool, even a small amount of muscle inhibition or atrophy in the small muscles of the palm can lead to a noticeable loss of function. Using supportive splints or performing specific hand-strengthening exercises can help maintain the dexterity and power needed for daily tasks. 

Investigating the causes of joint ‘giving way’ 

The sensation of a joint ‘giving way’ or feeling like it might collapse is a specific type of weakness. It is often caused by a sudden, sharp pain that triggers an immediate inhibitory response from the brain, causing the muscles to ‘relax’ for a split second. In other cases, it may be due to a loose fragment of cartilage or bone (a ‘loose body’) getting momentarily caught in the joint mechanism, which the brain interprets as a sudden threat. Keeping the muscles strong provides a ‘buffer’ that can help prevent the joint from actually collapsing when these sensations occur. 

Identifying triggers for increased weakness 

Joint weakness is often worse during certain times or after specific activities. Recognising these triggers can help you plan your movements more safely. 

Typical triggers for increased weakness include: 

• Fatigue: After a long walk or a busy day, the already inhibited muscles tire more quickly, making the joint feel much less stable. 

• Cold Weather: Low temperatures can make muscles less responsive and increase joint stiffness, which the brain may react to with more inhibition. 

• Prolonged Rest: Muscles that have been still for a long time may feel ‘sleepy’ and weak during the first few minutes of movement. 

• Acute Pain Flares: Any sudden spike in joint pain will likely increase the level of arthrogenic muscle inhibition. 

Differentiation: OA weakness vs Neurological conditions 

It is essential to distinguish the weakness caused by osteoarthritis from the weakness caused by neurological conditions like a pinched nerve or a stroke. Weakness from osteoarthritis is usually localised to the area around the painful joint and is often worse when the joint is at its most symptomatic. In contrast, neurological weakness may be accompanied by significant numbness, tingling that travels down the entire limb (sciatica), or a complete loss of muscle control. If your weakness is accompanied by a loss of bladder or bowel control, sudden facial drooping, or if you cannot lift your foot at all (foot drop), you should seek urgent medical evaluation to rule out a serious neurological or spinal issue. 

Conclusion 

Osteoarthritis frequently causes weakness in the affected joint through a combination of protective brain signals, muscle atrophy from disuse, and a loss of joint stability. While this weakness can make daily activities more challenging and increase the risk of falls, it is a highly treatable symptom. By engaging in consistent, low-impact strengthening exercises, individuals can ‘re-train’ their muscles to support the joint and overcome the brain’s inhibitory reflexes. Strengthening the muscles not only improves physical power but also provides a vital layer of protection for the remaining joint cartilage. Most people find that as their strength improves, their sense of balance and confidence in their mobility increases significantly. 

If you experience severe, sudden, or worsening symptoms, call 999 immediately. 

Authority Snapshot 

This article was written by Dr. Stefan Petrov, a UK-trained physician with an MBBS and postgraduate certifications including Basic Life Support (BLS), Advanced Cardiac Life Support (ACLS), and the UK Medical Licensing Assessment (PLAB 1 & 2). He has hands-on experience in general medicine, surgery, anaesthesia, ophthalmology, and emergency care. Dr. Petrov has worked in both hospital wards and intensive care units, performing diagnostic and therapeutic procedures, and has contributed to medical education by creating patient-focused health content and teaching clinical skills to junior doctors.