Why Women Are More Prone to Knee Injuries than Men - Essay Example

Why women are more prone to knee injuries than men The knee, or tibiofemoral, joint is the largest and one of the most complex and most frequently injured joints in the body. Compared to the hip joint, the knee joint is relatively unprotected by surrounding muscles. Consequently the knee, more often than the hip, is injured by blows or sudden stops and turns. Athletes, for example, frequently tear a knee cartilage, that is, one of the menisci. In most of our day-to-day activities- even such ordinary ones such as walking, going up and down stairs, and getting into and out of chairs- our knees bear the brunt of the load; they are the main weight bearers. Knee injury or disease, therefore, can be badly crippling .(Thibodeau 223). A women's work is never done! So goes the age-old saying. Although in today's world there are many labor-saving devices, the modern woman often carries responsibilities involving long hours of duty. Women employed in industry or with major home-care responsibilities can be involved in a variety of tasks requiring strong mental, physical, emotional and social abilities. For many, additional burdens exist. Te career woman with a family, the pregnant woman with several children, the woman caring for a disabled child or an ageing parent and the wife and mother confined to a wheelchair are all faced with the challenges of coping with prolonged demands on both their energy and time. Some traditionally female jobs in the workforce are also susceptible to special stresses (Sapsford 268). The knee joint is the major weight-bearing joint of the body. Any condition, which interferes with the smooth articulation of the joint, leads to instability and rapid wasting of the quadriceps muscle (Anne 548). Cancellous bone loss begins between the ages of 30 and 35 with yearly decrease in women of 0.6 % to 0.8 % (Linear decrease) or 2.4 % (curvilinear decrease). Age-related cancellous loses in women appear to begin up to a decade earlier than cortical bone loss. Women may lose 50% of cancellous and 30 % of cortical bone over their life times, whereas men may lose only 30 % and 20 % respectively. In addition, women may have an increased risk for osteoporosis because throughout life they have 30 % less bone mass than men of a similar age (Kimble 48.28). Throughout its life bone can respond to external forces (or loads) such as the pull of tendon on bone and weight bearing. These forces can help to maintain bone mass or increase it in some circumstances. As a living tissue, bone material is constantly being turned over in a process called bone remodeling. In this process old bone is resorbed and new bone is formed. Many internal factors dictate the effectiveness of the remodeling process. These can include ageing, hormonal influences, metabolic variations and certain disease processes. Bone is most sensitive to mechanical loading during childhood (Sapsford 134). An increase in osteoblastic activity and thus in bone mass can result from the external forces (or loads) mentioned. Without these forces osteoclast activity (bone resorption) predominates and bone mass decreases (Norkin and Levangie, 1992). If the breakdown or resorption of bone (osteoclastic activity) then decreased bone density or osteopenia will occur. If this process continues unchecked it can lead to osteoporosis. Osteoporotic bone is more likely to fracture than bone of normal density (Sapsford 412). Osteoporosis in a major health problem that affects over 9.4 million people on the United States and is especially prevalent among postmenopausal women. The incidence osteoporosis increases with age; 30 percentage of women between the ages of 70 and 79 and 70 percentage of women 80 years of age or older develop osteoporosis without medical intervention (Kimble 48.30). There is much grater risk of women developing osteoporosis than men. Suggested reasons for this include the fact that after menopause women have period of rapid bone loss as a result of a sharp fall in oestrogen levels as overian function ceases. Up to 15 % of bone can be lost within 5-10 years of menopause. Surgical removal of the ovaries can also result in rapid acceleration of loss of bone mineral content if hormone replacement therapy is not prescribed. Men do not experience a similar rapid drop in testosterone, which is responsible for bone mass in males. Also worth noting is that males tend to have greater muscle mass than females and that this may be protective (Sapsford 420-21). When menopause occurs early in a woman's life there is a longer period of time when her bones are not protected by estrogen and this increases her chance of developing osteoporosis. An early menopause may also be a result of hysterectomy. Interestingly, a delayed puberty may predispose to low bone density in women. The significance of heredity as a risk factor for osteoporosis is being studied. It has been proposed that approximately 75 % of the genetic effect on a person's chance to develop osteoporosis is due to a particular allelic variant in the gene that is responsible for encoding the 1, 25-dihydroxyvitamin D receptor. This study suggests test heredity may be important in the development of osteoporosis. Women with a first -degree relative with osteoporosis typically have low bone mass (Sapsford 422). Calcium, in conjunction with vitamin D, is needed to strengthen bones, increase bone mass, and decrease fracture rates. Girls and women need an adequate calcium intake to achieve and help maintain optimal bone mass, but the typical American diet is low in calcium (Kimble 48.29). Although not regarded as a risk factor for the majority of breast-feeding women, the effect of lactation on the bone of healthy women must be mentioned. During lactation, 160-300 mg per day of maternal calcium is lost through the production of breast milk. (NIH 1994). Pre-menopausal bone density is similar in smokers and non-smokers. Women who smoke tend to have an earlier menopause than their non-smoking counterparts. Thus the smoker is exposed to more time without estrogen protection for her bones. Bone mass peaks during the third decade of life. At about 35 years of age, cortical bone gradually begins to decrease 0.3 % to 0.5 % yearly in both women and men. With menopause, the decline in 17 estrdiol concentrations further accelerates cortical bone loss by 2 % to 3 % per year that is superimposed on age -related bone loss. This hormone related accelerated bone loss could also occur after surgical oophorectomy (Sapsford 320). Women who smoke, especially those who are thin, have an increased risk for fractures compared with nonsmokers (Kimble 48.28- 48.30.). Maturational assessment (classified via the attainment of sexual characteristics, e.g development of genitalia, presence of public hair) measures and adolescent's progression towards physical maturity. This assessment is important as a marker of physical ability and potential compared to chronological age. Its usefulness is highlighted when considering injuries caused by loss of flexibility and muscle -tendon imbalances. Pre- and post-pubertal growth spurts can be reliably predicted via maturational assessment. Biomechanical changes can be monitored during these growth spurts and the physiotherapist can advise the individual, parents and coaches on training programmes and sport participation. Emphasis on stretching activities is warranted. When this does not occur the skeletally immature athlete is at risk of injury. Training errors involving inadequate warm-up and cool-down sessions, rapid increases in the intensity, frequency and/or duration of sessions and changed footwear or training surface will all contribute to overuse injuries. Adolescence is also a time of great hormonal adjustments. Apart from menopause and pregnancy there is no other time in a female's life when significant hormone changes take place. Hormonal and orthopedic factors combine to cause a significant evolution within the young girl's body. The extraordinarily rapid physiological and physical changes which occur during the ante-natal and post-natal period require significant musculoskeletal adaptation. These changes may be implicated in the development of pain syndromes, which may need to be controlled or relieved by physiotherapy intervention. In addition, latent problems of a musculoskeletal nature existing prior to pregnancy may be exacerbated due to the pregnancy itself or the woman may sustain a musculoskeletal injury unrelated to the pregnancy. In the 1990s female adolescents are playing a variety of sports that influence the neuromusculoskeletal system. Traditionally girls have been involved in sports such as netball, softball, gymnastics, swimming and athletics. With more sports being available to the public at large, activities that have previously been considered the sporting domain of males, such as cycling, basketball and rugby union, are attracting adolescents girls. The influence of growth in combination with the varied demands of different sports means that there are many orthopedic conditions that are unique to the growing child/adolescent (Sapsford 15). Rapid alterations in lower limb biomechanics during adolescence also predispose the female to conditions of overuse. Girls participating in running and jumping sports are particularly susceptible. Rapid bone turnover during the teenage years results in a higher incidence of fractures, especially in the physically active subset (Parfitt, 382). Rapid bone growth occurs during puberty, which for females is 9.5 - 14.5 years of age. Approximately two years after the commencement of puberty, girls achieve their peak height velocity (PHV). On average peak height velocity is 8 cm per year, with the average age of PHV in girls being just above 12 years of age. Six to twelve months prior to menarche, girls will reach their maximal growth rate and maintain this rate for two to three months. Only 5 - 10 percentage of adult height will be gained after menarche but girls may continue growing linearly up to 19 years of age. In most instances, however, linear growth has ceased by 17 years. The epiphysial plates located at either end of the bones allow longitudinal growth and are the site for formation of joint surfaces. Apophyses are also bony growth sites and are where major tendons and ligamentous groups attach. The two areas where bone formation occurs are zones of inherent weakness and are therefore susceptible to injury during the growth phase. Developing bone is particularly adaptable to different mechanical loads and this ability to 'remodel' itself decreases once maturity is reached. Consequently, physical exercise during childhood and especially puberty has a significant effect on bone growth and development. The growth plate relies on the fibrous periosteum that inserts into the epiphysis and perichondrium to stabilize it biomechanically and minimize the risk of injury. Ligaments and tendons attach at the perichondrial zone and the tension that these structures receive is transferred to the growth plate. The ligaments that surround the growth plates are 3-5 times stronger than the epiphyseal plate, which results in adolescents sustaining injuries of the growth plate more frequently than the ligamentous damage that occurs in adults Due to the influence of ligamentous tension on it, the growth plate is most susceptible to a torsional stress; Pivoting on a fixed foot in netball is a classic example of fracture mechanism. Due to anatomy and biomechanics associated with the injury, growth plate fractures commonly occur at the knee joint. Eating disorders and/or menstrual problems such as amenorrhoea have also been associated with stress fractures in teenage athletes. Avulsion fractures of the tibial tuberosity are commonly seen in adolescents between 12 and 16 years of age. This is just before the apophysis fuses with the tibia. There can be two mechanisms of injury: a strong quadriceps contraction when the knee is flexed and the foot fixed or a violent passive flexion of the knee when the quadriceps are contracted maximally. Commonly, these occur in motor vehicle accidents or contact sports such as basketball or rugby for females. Significant changes in lower limb biomechanics occur during the adolescent growth spurt. The female pelvis is wider than in males and affects the biomechanics of other lower limb joints, particularly the knee joint. Carbon (1992) considers that this anatomical difference disadvantages the female in weight-bearing sports. Pain or discomfort about the knee is commonly reported during adolescence. Female basal levels of the hormone relaxin are higher than in the adolescent male population, resulting in greater joint flexibility. This is most commonly seen at the shoulders, knees, ankles and patellofemoral joints. Overuse syndromes such as swimmer's shoulder and thrower's (little leaguer's) elbow may occur as a result of poorly stabilized joints undertaking large ranges of motion at high repetitions and forces. Bones grow faster than associated musculotendinous structures and alterations in flexibility and a propensity for muscular imbalance are reported. These imbalances contribute to alterations in limb alignment. In the lower limb this can result in gait pattern disturbances that may predispose the growing athlete to chronic injury. These problems are more commonly seen in the growing female who is already biomechanically disadvantaged. Overweight and obesity are recognized by health professionals as predisposing factors for cardiovascular disease (CVD), hyperlipdaemia, osteoathritis, and some sex hormone-sensitive cancers such as breast and endometrial cancer, and sleep apnoea (Sapsford 16-18). Increase in body weight is strongly associated with hip and knee osteoarthritis. In the Framingham Study, those in the highest quintile of body mass at the beginning of 36 years of follow-up had a relative risk for developing knee osteo arthritia of 1.5 for men and 2.1 for women. For severe knee osteo arthritis these values were 1.9 for men and 3.2 for women (Gelber 1999). A twin study in women showed that for every additional kilogram of body mass, the risk of later developing osteoarthritis increased by 9% to 13% (Cicuttini1226). During post menopause, lean body mass (muscle) decreases and fat mass increases Consequently the BMR decreases, which adds to the problem of weight control. Common presenting complaints around the transition to menopause are muscle aches and joint pains. Joint pains may occur due to a decrease in the collagen of ligaments and articular soft tissues. In addition, rheumatoid arthritis is more prevalent in women of this group and Hall and Spector (1994) have commented on the usefulness of HRT as a therapeutic adjunct in the treatment of rheumatoid arthritis. Muscular changes relate to an overall decrease in muscle mass. This decline can be attributed to a decrease in both strength and endurance of the muscle. Factors associated with these declines are height changes, weight increases and a decreased level of activity. The result of these changes in inevitably a higher risk of falls and subsequently of fractures as well as a decrease in fitness levels. The cellular components of bone include osteoblasts and osteoclasts. Osteoblasts are responsible for the laying down of new bone while osteoclasts are responsible for bone resorption. The following is a brief synopsis of the process that occurs as our bone age and change according to different influences. A number of inter-relating factors may exist in the female athlete including training intensity, low percentage body fat, low calorie intake and high protein intake. Amenorrhoeic athletes may have bone mineral densities 10% less than their eumenorrhoeic (normal) sedentary counterparts. Decreased bone formation and increased bone resorption can occur due to the lack of gravitational and mechanical forces on bone. Immobilization can also lead to muscle weakness and decreased balance and co-ordination. The risk of falling may increase (Sapsford 422). References Cicuttini, FM., and Baker, JR and Spector TD. "The association of obesity with osteosrthritis of the hand and knee in women: A twin study" J Rheumatol23 23(1996). 1221-1226. Anne Footner. Orthopaedic Nursing. Second ed. London: Bailliere Tindall, 1989. Gelber AC., Hochberg MC and Mead LA. "Body mass index in young men and the risk of subsequent knee and hip osteoarthrits". Am J Med 107(1999). 542-548. Kimble, MA, Koda., Lioyd YY., Wayne AK., BJ Guglielmo., BK. Alldredge and RL. Corelli. Applied Therapeutics. The Clinical Use of Drugs. 8th ed. Tokyo: Lippincott Williams and Wilkins , 2005 National Institute of Health (NIH) (1994). Consensus statement. Optimum Calcium Uptake. 12 (4): 13 Norkin, CC and Levangie, PK. Joint structure and function: A comprehensive analysis. Philadelphia: FA Davis Co,1992. Parfitt AM. "The two faces of growth: benefits and risks to bone integrity". Osteoporosis International 4(1994): 382. Sapsford, R., JB, Saxton and S, Markwell. Women's Health A Textbook for physiotherapists. Harcourt Brace and Company Asia PTE LTD: Singapore, 1998.15-19, 20-21, 29, 319-320, 134-135, 268, 412-413, 420-422, 424. Thibodeau GA. Anatomy and Physiology. Wiscosin. 223 Read More