Knee Osteoarthritis - Special Considerations for Midlife Women
Keep your knees working for you for life!
Joint pain is one of the most common symptoms that midlife women experience -especially active women! And for good reason! As estrogen and estrogen receptor activity decline, changes in the muscles, tendons, bone, and even pain receptors result in discomfort, stiffness, and many times reduced function.
This review published in the June 2022 issue of Menopause from the Department of Physical Medicine and Rehabilitation at Spaulding Rehabilitation Hospital in Charlestown, Massachusetts discusses the physiology, prevention, and management of knee osteoarthritis (KOA) in midlife women. I have summarized the key points of this article here.
Knee osteoarthritis in midlife women: unique considerations and comprehensive management
Curry ZA et al. Menopause vol 29, No. 6, pp 748-755 2022
Goal of this study:
To describe the unique pathophysiology of KOA and treatment considerations for menopausal women.
Type of study:
Review of the peer-reviewed medical literature related to the pathophysiology, diagnosis, and treatment of KOA with a focus on menopausal women.
KOA affects up to 16% of adults age 50 and over in the US with up to 60% of patients with KOA being women. KOA can be disabling in older menopausal women with mobility issues, difficulties with self-care, and performing usual activities of daily living.
The normal knee joint:
The knee joint provides articulation between the femur (thigh bone), tibia (shin bone) and the patella (knee cap).
Movements include flexion, extension and a small degree of rotation.
The knee joint is stabilized by ligaments (connective tissue from bone to bone) on both sides (medial and lateral collateral ligaments) and front and back (anterior and posterior cruciate ligaments).
The articulating surfaces of the femur and tibia are lined with cartilage, which serves as shock absorption and provides a smooth articulating surface and is lubricated by synovial fluid.
Knee extensors (ex quadriceps muscles) absorb shock to the knee and stabilize the joint.
Pathophysiology of KOA:
Due to age-related degenerative changes in cartilage and bone.
Chronic inflammation is thought to play a key role in degrading the cartilage that lines the articulating surface of the joint. Pain results from local tissue damage and possibly through the accumulation of immune cells and mediators in the nerve roots leading to the central nervous system.
Recent studies suggest a role for the bone underlying the cartilage surface (subchondral bone) in the pathogenesis of KOA where lower bone mineral density was associated with high-grade KOA seen on X-ray. With the declining bone density noted in menopause, midlife women are at particular risk.
The changing hormones of the menopause transition also impact pain perception.
Interestingly, the age of menopause onset is not associated with the risk of KOA which raises questions about the role of hormones in this process.
Newer studies show a lower prevalence of KOA in menopausal hormone therapy (HT) users, likely related to the preservation of subchondral bone and cartilage. However, significant discordance remains among studies, again underscoring the complexity surrounding the role of hormonal change in KOA development.
The angle of weight/biomechanical force transmission from the hips to the knees in women as compared to men plays a significant role in joint instability and cartilage damage to the medial (toward the middle/inside) aspect of the knee joint. Obesity exacerbates these effects resulting in hip pain and reduced physical activity and mobility.
Diagnosis and Assessment
Dull pain in one or both knees. Pain may be in the whole knee or localized and is worse with activity and better with rest. Knee pain may be accompanied by hip pain affecting walking stride, mobility, and activity level.
Knee pain may be accompanied by vasomotor symptoms (hot flashes) that may impact sleep which in turn may impact pain perception.
A thorough physical exam of the knee and attention to the hip along with x-rays are standard of care. Functional testing such as sit-to-stand without the use of the arms and single-leg squats are also helpful in the initial assessment.
Prevention is King! Regular physical activity, weight management, lower body muscle strengthening, aerobic exercise, sound nutrition and minimizing inflammation are the mainstay for optimal knee health.
Physical therapy that targets specific deficiencies.
Neoprene sleeves: Increase proprioception, and support knee alignment.
Topical therapeutics: Topical non-steroidal anti-inflammatory (NSAID) cream (ex- Diclofenac)
Oral therapeutics: NSAIDs for acute flares. Caution must be exercised with longer-term use due to gastrointestinal effects and impact on kidney function. Pain control with serotonin-norepinephrine reuptake inhibitors (SNRIs) or GABA targets nervous system pain transmission/perception. Improvement in sleep may also improve pain perception.
Injections: May be considered when conservative measures fail and should be used sparingly. Steroid and local anesthetic injections are the most common. Although effective for short durations, these agents may be toxic to cartilage. Alternatives include injections with hyaluronic acid and its derivatives, prolotherapy, platelet-rich plasma, bone marrow aspirate, and adipose transfer. However, these alternative therapies have limited evidence of effectiveness and some may not be FDA approved.
Knee Replacement: When all other conservative management strategies have failed, when pain and functional limitation are severe.
In My Humble Opinion….
The physical changes that accompany midlife have widespread effects on physical functioning - and our joints are a significant part of that equation. As with other physical changes of menopause, the foundation of optimal joint (and overall health) is sound nutrition and varied physical activity with a central focus on aerobic training and muscle strengthening. Not only do physical exercise and nutrition support the muscles and bones, but it is the cornerstone of a healthy metabolism and weight management, which reduces undue stress on joints, and promotes long-term mobility and functionality until late in life.
If you have established KOA, there are a multitude of interventions that are available to help you manage pain, improve function and have your knees working for you for life!