An Examination of the Relationship between Gender and Knee Range of Motion

Transcription

1 An Examination of the Relationship between Gender and Knee Range of Motion Courtney Rogers, Saint Martin s University, 5300 Pacific Avenue SE, Lacey, WA This work was supported by Saint Martin s University. Abstract This study was investigated whether there is a difference between male and female knee range of motion (ROM).The hypothesis being tested is whether injured females have a more decreased ROM than injured males. Participants were grouped according to injured and noninjured knees within their gender. The knee flexion and extension of each subject was measured with a goniometer. The results showed that compared to a normal ROM of flexion of 140º and an extension of 0º, injured females have a more decreased motion of flexion while injured males had a more decreased motion of extension. My results showed injured females to have an average flexion of 118.5º and an average extension 3.50º. The injured males of my study had a flexion average of 128.0º and average extension of 4.0º. The difference between non-injured females and injured females was 6.6º of flexion and the difference between non-injured males and injured males was 1.0º of flexion. When comparing injured males to injured females there was a difference of 9.5º of flexion and 0.5º of extension. These results suggest that injured females have a more decreased flexion while injured males have a more decreased extension. Introduction The largest and most complex joint in the body, the knee, constantly undergoes tremendous stress as it absorbs the impact of full body weight during physical activity (Austermuehle, 2001). Although there are many different reasons for a knee injury, it is how the injury affects the body that is important. Whatever the underlying injury, the basis of the treatment plan is a timely diagnosis, which helps ensure that the patient regains full and pain-free use of the joint (Austermuehle, 2001). An injury to a knee can directly affect the knee range of motion due to lack of flexibility or the shortening of ligaments. Many studies define motion loss as a deviation of 5 from full extension (Millet et al., 2001). For the knee, any motion loss could be debilitating. Knees are complex structures consisting of jointed bones, cartilage, muscles, tendons and ligaments. Tilton (1998) discusses the anatomy of the knee by explaining that three bones affect how your knee functions: the femur, which is the thigh bone; the tibia, which is the shin; and the patella, which is the kneecap. In between the bones, there are two pieces of c-shaped cartilage, one lateral (outside of knee) and one medial (inside of knee). This cartilage, along with fluid-filled sacks called bursae located at the points of greatest friction, helps absorb shock when you walk (Tilton, 1998). Knee ligaments, which connect bone to bone, and are attached at points of high stress. Ligaments on the inside and outside of the knee provide stability during side-toside motion. The cruciate (crossed) ligaments run through the joint between the cartilage and provide back-to-front and front-to-back stability (Tilton, 1998). Along with bones, cartilage, and ligaments, the muscles and tendons give the knee stability and support when in movement. 245

2 Austermuehle (2001) discusses the most common knee injuries and their causes. Her study found that the most common knee injuries are to the anterior cruciate ligament (ACL), the medial collateral ligament (MCL), and acute injuries to the menisci. The mechanism for the ACL injury is a noncontact pivoting or twisting injury with the foot planted. This commonly occurs in tennis and basketball. Other mechanisms for this injury are a non-contact hyperextension, sudden deceleration, forced internal rotation, or a sudden valgus impact. Usually when this happens, the patient is disabled immediately, is in extreme pain, and may hear a pop noise at the time of injury. The MCL mechanisms of injury reported in her data include valgus (contact) stress or an external rotation with the leg planted on the ground. These are most commonly seen in football and basketball. Injuries to the menisci occur more often to the medial menisci than the lateral, the mechanism for injury is the following; non-contact injury and a rotational force applied to a partly of completely flexed knee. These injuries commonly happen in tennis, or when in a squatting position and coming to a standing position rapidly. The lateral collateral ligament (LCL) and posterior cruciate ligament (PCL) are rarely injured (Austermuehle, 2001). The true incidence of motion problems after ligament injury to the knee is unknown and varies according to the specific injury, treatment modality, and how motion loss is defined (Millet et al., 2001). Range of motion (ROM) is the complete movement of the joint and is based on a common scale of degrees(fig.1). The range through which a joint can be moved is its range of flexion and extension (MedicineNet, Inc.). ROM is assessed by extending and flexing the knee as far as possible (normal range of motion: extension, zero degrees; flexion 135 degrees) (Calmbach and Hutchens, 2003). There are numerous variables that can affect the range of motion in the knee; a few examples are gender, age, and injury. Numerous studies have investigated the nature of ACL injuries and possible explanations for the differences in injury rates between genders (James et al., 2004). In a study by Smith (2000), the primary focus was the occurrence of ACL injuries in women. Overall, women are six to eight times as likely as men to sustain some kind of knee injury (Wong, 2004). The ACL is one of the four ligaments that connect the thighbone (bottom of the femur on the intercondylar notch) to the shinbone (top of the tibia plateau) and keeps the knee stable as it rotates. Wong (2004) examined the fact that women are more vulnerable to ACL injury than men. Some doctors viewed this in the past as just weakness of the knees. Research has been conducted to examine the topic and has shown that there are inherent anatomical differences between male and female athletes, differences in pelvic width and alignment of the leg bones, which make women more likely to injure their ACL (Smith, 2000). Because the cause of their ACL injuries is more anatomical, there is little that can be done to prevent the injury. However, strengthening the surrounding muscles can protect the ligament. Strength in the hamstrings has been shown to protect the ACL from excessive strain; women, however, tend to be stronger in the quadriceps, creating an injury proneimbalance (Smith, 2000). Figure 1. The degrees of movement for the knee (Zimmer, Inc.). 246

3 A study by Abdulla (2005) found that women are more likely to tear their ACL in sports than men, and the incidence of occurrence in knee injuries of females is 5 times higher per player per hour than males. The common ages of occurrence in females are from years and there are some speculations as to why the ACL injury is so common. The research focused on the anatomical and hormonal differences among men and women. Women have greater pelvic widths, a larger Q angle, greater hip varus, hip ante version, knee valgus and foot pronation (Abdulla, 2005). Some researchers also found that women are three times more likely to injure their ACL during ovulation, when estrogen levels are at their peak, than when they are menstruating. These differences between men and women can make women more likely to suffer knee injuries. More researched was conducted, however, to reach a more conclusive understanding of why women have a higher risk of ACL injury than men. Researchers have found that a large portion of knee injuries in general and 70% of ACL tears are from non-contact injuries. There have been reports of women having poor hamstring, gluteus medius, and calf muscle recruitment patterns, greater flexibility, poor patellar tracking, tend to use less hip and ankle musculature during sport and tend to land flat footed with the knee in extension rather than partial flexion (Abdulla, 2005). The best methods in preventing ACL injury among women athletes is proper stretching and muscle strengthening. Loss of motion after ligament injuries to the knee is a common problem that may involve loss of flexion, extension, or both (Millet et al., 2001). This article presented extensive information of loss of motion which corresponds to range of motion of the knee. In this study, they calculated knee flexion and then were able to see the differences in loss of motion, where normal knee flexion was approximately 140 in men and 143 in women. When patients were given a one year follow up after ACL surgery, the doctors found that 11 % had motion loss, which was defined as a loss of extension of 10 or greater, or flexion less than 125. Knee injuries affect more than 3 million Americans each year and are commonly seen in primary care (Austermuehle, 2001). According to this statistic, knee injuries are common and will stay a constant in the medical profession unless proper prevention information is established. However, even with proper prevention techniques injuries will still occur. In this research, I evaluated the knee ROM. Participants sat at the edge of a table and then flexed and extended their knees while I measured their ROM in degrees using a goniometer. After collecting this information, I compared it to the ROMs collected from other participants. Before I measured the ROM, a participant filled out a survey; this allowed me to group the participants. The measurements in my study included the comparison of knee ROM in male injured, male non-injured, females injured, and female non-injured participants. I chose to keep the participants around the same age range because the study from Abdulla (2005) stated knee injuries occur mostly from ages years. The different ROMs gave me a good indication of a healthy range of motion and how the injured ROM compared (decreased or increased). For this research, I obtained male and female participants for injured and noninjured groups, measured their ROMs, and analyzed the data to test whether injured females ROM is more decreased than male. Because most scientific research concluded that females are more likely to be injured than males, I focused on injuries and the 247

4 difference between genders. My hypothesis was that injured females have a more decreased ROM than injured males. Methods Subject Recruitment and Survey I sent out an to the students at Saint Martin's University to get varied participants for this study. However, I did not get an adequate response from the e- mails, so I approached people and members of sports teams to ask if they would take part in my study. I also asked for participants from biology senior seminar class. The total number of participants was 22, with 12 females and 10 males. When I met with participants, I first had them fill out a consent form and then a survey (Figure 2). The survey questions I used to categorize the results into subgroups are shown in Figure 2. Based on their survey responses the participants were divided into subgroups of male non-injured, female non-injured, male injured and female injured. The controls for this study were male and female non-injured. ROM Measurements To measure the knee ROM I only measured the right knee to be consistent, however, the ROM in the injured individuals was measured only on the injured knee. Active extension and flexion are best evaluated with the athlete in a supine position (Shultz et al., 2000). I followed the directions from Shelbourne and Davis (1999) when they explained how to measure accurate range of motion with a goniometer. To test the flexion of the participant, I had the participant sit on a high table with their legs on the table. They either laid on their back or in a sitting position with their right knee up and foot flat on the table as close to the buttocks as possible (Figure 4). The left leg stayed flat on the table. The degree of the right knee was then measured using the goniometer. According to Shultz et al. (2000) the best way to test for extension is to have the participant sitting on the edge of the table with both of their legs hanging down. To measure extension I had the participants slowly extend their right leg as far as it could go (Figure 5). The degree of the extended right knee was then measured using the goniometer. Statistical Analysis I used a t-test to compare the means of two groups. This analysis was appropriate, because I compared the means of male knee ROM and female knee ROM. First, I established my control group, male and female non-injured. When their data had been collected, I calculated the mean of their group. Then, I took the results from the male injured and female injured to find the mean. The final step was to put all the numbers into the t-test formula (Figure 3). t= XT - XC vart varc nt + nc Figure 3. t- test equation. I used to program Minitab to calculate all of my results. I inserted my values for the flexion and extension of male, female noninjured and male, female injured. I then used the t-test to produce the t-values, p-values and DFs. Using this program I was then able to get a numbered difference between the groups to see if there was a more decreased knee ROM. 248

5 Figure 2. Survey given to participants of study before their knee ROM was measured. Saint Martin's University Senior Biology Project Thank you for all who are participating in this study. My name is Courtney Rogers and I am a senior majoring in biology. For my senior project I am trying to compare the range of motions from different divisions among the population to determine what affects the range of motions of the knee joint. Please answer the following questions truthfully, for your answers will help determine results. This is the first survey I am handing out, if the answers will help with this research you will be asked to participate in an experimental study. 1. Please check the following. Male Female 2. Have you ever had a knee injury? Yes 3. If yes, was the injury severe enough to need medical attention? Yes 4. If yes, please explain what type of injury and how severe it was. What type Just swollen, nothing torn Hospitalized, but no surgery Other, please explain. 5. Was surgery needed to correct the injury? Yes 6. Do you play, or have played any sports? High school, Collegiate or Recreational? Yes Collegiate Recreational High school 7. If yes, what sport? 8. Did the knee injury occur during the sports activity? Yes, which one(s)? 9. If you had a knee injury has it affected your performance? Yes, how? 10. Can the information provided be used with your consent? Yes 11. Would you be interested in the experimental part of this project, where your knee ROM will be measured? Yes 10. Please leave your contact information. 249

6 Figure 4. This the leg in the flexion position (Shultz et al., 2000). Figure 5. This the leg moving to the extension position to be measured (Shultz et al., 2000). Results Participants were divided into subgroups of Female Injured, Female Non- Injured, Male Injured, and Male Non- Injured. By dividing the groups in this manner, I was able to compare the knee range of motions (ROM) more easily. The null hypothesis for this experiment was that there would be no significant difference in ROM: Ho= all means same (µ¹=µ²=µ³=µ4).the alternative hypothesis for this experiment was that there would be a difference between the average ROM: Ha= all means not the same (µ¹ µ² µ³ µ4). I found a statistically significant difference among groups and comparatively between males and females. I found that the degrees of both flexion and extension varied when compared with my preliminary research. When female injured was compared with male injured, the results found for flexion were the p-value= 0.121, DF= 7, and the t-value= This was at a 95% individual confidence level. The results for extension found were the p-value=0.719, DF=7, and the t-value= Female noninjured was also compared to male noninjured and the results found were that at flexion p=0.678, DF=11, and t-value= At extension the results for male and female non-injured were p-value= 0.028, DF=11, and t-value=2.53. By comparing the flexion and extension between injured and non-injured we are able to see the differences between the male and female participants knee ROM and how they are affected by their injuries. According to this research injured females have a more decreased ROM in flexion, but injured males have a more decreased ROM in extension. In Table 1. and Table 2. the average ROMs for flexion and extension are given as well as their Standard deviations to show the differences between the participants. Figure 5 and Figure 6 are also used to show the differences between the average knee ROMs of participants for flexion (Fig 6.) and extension (Fig 7.). 250

7 Table 1. Average ROM for flexion of participants and their St. Dev. (p-value= 0.121; DF= 7; t-value= -1.77) Category Number of Participants Average ROM for flexion St. Dev. For flexion Male Non-injured º 5.58 Female Non-injured º Male Injured º 6.57 Female Injured º Table 2. Average ROM for extension of participants and their St. Dev. (p-value=0.719; DF=7; t-value= -0.37). Number of Average ROM for St. Dev. For Category Participants extension extension Male Non-injured Female Non-injured Male Injured Female Injured Flexion in Degrees Female Non-injured Female Injured Male Noninjured Male Injured Participants Figure 6. Is the comparison of average flexion between all groups with an error bar one standard deviation from above the mean. (p-value= 0.121; DF= 7; t-value= -1.77) 251

8 Extension in Degrees Female Noninjured Female Injured Male Injured Male Noninjured Participants Figure 7. Is the comparison of average extension between all groups with an error bar one standard deviation from above the mean. (p-value=0.719; DF=7; t-value= -0.37) Discussion According to Millet et al., 2001, the normal knee flexion is approximately 140 in men and 143 in women. My research showed that the flexion mean of non-injured females was 125.1º, while the non-injured males had a mean of 127.0º. For injured knees Millet et al., 2001, defined motion loss as a loss of extension of 10 or greater or flexion less than 125. My results showed injured females to have an average flexion of 118.5º and an average extension 3.50º. The males of my study had a flexion average of 128.0º and average extension of 4.0º. The difference between non-injured females and injured females was 6.6º of flexion and the difference between non-injured males and injured males was 1.0º of flexion. When comparing injured males to injured females there was a difference of 9.5º of flexion and 0.5º of extension. Loss of motion after ligament injuries to the knee is a common problem that may involve loss of flexion, extension, or both (Millet et al., 2001). The results of my study had some mixed outcomes as far as supporting the hypothesis that injured women will have a more decreased range of motion compared to injured men. My research found that women do have a more decreased flexion than men, but their extension can be greater. Although my results are lower than previously reported results, there are many possibilities as to why there are much lower ROMs than expected. I found that it was harder for students to move their knee in the flexion position if they were wearing tight fitting clothing, such as jeans. This would constrict them and prevent them from moving their leg closer to their body. If I were to repeat this study, I would have the participants to either wear shorts or loose pants. Another possibility for the males to have a more decreased ROM than the females is that some had just recently been injured and that affected their performance in these tests. In a future study, I would not have allowed anyone with a knee injury less than a year old to participate. With this, the injured participants would most likely have had time to heal. It would also have been beneficial to compare time of injury and type of injury. 252

9 The last difference that affected my results was that there were not enough participants. I was only able to get half of what I wanted. Some students felt they had no time to participate or they just were not interested. If I had gotten more students, my results would have varied more than what they did. My hypothesis that injured females have a more decreased ROM than the injured males was partially supported by the flexion results; the injured females had a more decreased flexion than the injured males by 9.5º. However, the injured males had a more decreased extension of 0.5º. I do feel that I made progress in the fact that there was a difference between the injured female participants and the injured male participants. The one thing that I could not count on through research was the differences between humans and how hard it is to work with them. To give an average ROM for normal and injured knees doesn t really account for how much variability comes with all the different aspects of males and females and their lives. Acknowledgements I would like to thank Dr. Hartman and Dr. Olney for helping me with this project; their patience and input was crucial for me and my project. Dr. Porter helped me with my statistical analysis and trying to figure out what it all means. Sothear Sam, Krystle Anton, Ruby Lopez and Kyle Samples gave of their valuable time to view my practice presentation and to give useful input. My family also supported my research and project with helpful attitudes, especially Bobby. I would also like to thank all of my participants and their knees. Literature Cited Abdulla, A., Abdulla, F Preventing knee injuries in the female athlete. Patient Care. 16: Austermuehle, P. D Common knee injuries in primary care. Nurse Practitioner. 26: Beynnon, B.D., Johnson, R.J., Abate, J.A., Flemming, B.C., Nichols, C.E Treatment of anterior cruciate ligament injuries: Part I. American Journal of Sports Medicine. 33: Calmbach, Walter L., Hutchens, M Evaluation of patients with knee pain: Part I. History, physical examination, radiographs, and laboratory test. American Family Physician. 68: 907. James, R.C., Sizer, P.S., Starch, D.W., Lockhart, T.E., Slauterbeck, J Gender differences among sagittal plane knee kinematic and ground reaction force characteristics during a rapid sprint and cut maneuver. Research Quarterly for Exercise and Sports. 75: MedicineNet, Inc Definition of range of motion. Med terms dictionary. n/hp.asp [accessed 15 Nov. 2005] Millet, P.J., Wickiewicz, T. L., Warren, R. F Motion loss after ligament injuries to the knee. The American Journal of Sports Medicine. 29: Schultz, S.J., and Hoglum, P.A., Perrin, D.H., Assessment of Athletic Injuries. Human Kinetics: Champaign, IL, pg

10 Shelbourne, K.D., Davis, T.J., Evaluation of knee stability before and after participation in a functional sports agility program during rehabilitation after anterior cruciate ligament reconstruction. The American Journal of Sports Medicine. 27: Smith, I. K., On bended knee. Time. 20: 120. Tilton, B., Imagine a big hinge. Backpacker. 26:30. Wong, K The recipe for strong knees. Health. 18: Zimmer, Inc Figure 1. Knee ROM. obal/action/1/id/520/template/pc/nav id/598 [accessed April 18, 2006] 254

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