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TYPES OF KNEE INJURIES & HOW THEY OCCUR
By Matthew Donohoe, MA, ATC; Helen Aslanian, BS; and Kenneth Solomon, PhD, PE, Post PhD
³This article originally appeared in The Forensic Examiner (Vol 14, No. 1). It is being reprinted with permission of
the American College of Forensic Examiners. www.acfei.com, (800) 423-9737²
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Knee Chondromalacia
Chondromalacia is the softening and deterioration of the articular cartilage on the posterior surface of the patella. The exact cause of chondromalacia is unknown; however, it has been postulated that abnormal patellar tracking is a major etiological factor.13 Three stages of chondromalacia have been identified. Stage 1 involves the swelling and softening of the articular cartilage. Stage 2 involves the fissuring of the softened articular cartilage, and stage 3 involves deformation of the surface of the articular cartilage caused by fragmentation.3
Bursitis
Bursitis of the knee is the inflammation of one or more of the numerous bursae that surround the knee joint. Bursitis can be acute, chronic, or recurrent.2 Most commonly, the bursae in the anterior group become inflamed. Common mechanisms of knee bursitis include contact trauma, prolonged kneeling, and repeated flexion or extension of the knee.
Summary
Although the knee, at first glance, appears to be a relatively simple hinge joint that merely moves in flexion and extension, trauma to the knee can occur in many different manners, some of which are summarized in Table 1. However, in order to damage one of the specific structures of the knee, the mechanism required to injure that structure must be present or injury cannot result. Meniscal tears require compression, rotation and flexion, or extension. Ruptures of the anterior cruciate ligament occur as a result of rotation, abduction, posterior translation of the femur with respect to the tibia, hyperextension, or dislocation of the knee joint. Ruptures of the posterior cruciate ligament occur as a result of posterior translation of the tibia while the knee is flexed from hyperextension or hyperflexion. The medial collateral ligament will rupture as a result of a valgus force or external rotation. The lateral collateral ligament will rupture as a result of a varus force or complete dislocation of the knee. Bursitis of the knee is often a result of direct impact, prolonged kneeling, or repeated flexion or extension of the knee. While the causes of osteoarthritis and chondromalacia are not known, we do know there are risk factors that increase the likelihood of developing these problems. The risk factors for osteoarthritis include age, gender, previous trauma, and obesity, while abnormal patellar tracking is the risk factor for chondromalacia.
As can be seen, there is no doubt about the true complexity of the knee joint, the major processes that occur as people walk, sit, stand, run, and jump, and the debilitating injuries that can occur when external and internal forces cause the structures of the knee to exceed their physical limits.
References
- Altman RD. The classification of osteoarthritis. The Journal of Rheumatology. 1995;Vol. 22; Suppl. 43:42-43.
- Arnhein DD, Prentice WE. Principles of Athletic Training. 8th ed. St. Louis, MO: Mosby Year Book;1993.
- Cailliet R. Knee Pain and Disability. 2nd ed. Philadelphia, PA: FA Davis; 1983.
- Cross MJ, Chrichton, KJ. Clinical Examination of the Injured Knee. Baltimore, MD: Williams & Wilkins; 1987.
- Dox IG, Melloni BJ, Eisner GM. The Harper Collins Illustrated Medical Dictionary. New York, NY: HarperCollins; 1993.
- Enerson OD. 2003. Retrieved from: www.whonamedit.com/synd.csm/2251.html.
- Fanelli GC. Posterior Cruciate Ligament Injuries: A Practical Guide to Management. New York, NY: Springer-Verlag; 2001.
- Felson DT, Niamark A, Anderson J, Kazis L, Castilli W, Meenan RF. The prevalence of knee osteoarthritis in the elderly. Arthritis and Rheumatism. 1987;Vol. 30;914-918.
- Hoppenfeld S. Physical Examination of the Spine and Extremities. East Norwalk, CT: Appleton & Lange; 1976.
- Kapit W, Elson LM. The Anatomy Coloring Book. 2nd ed. New York, NY: HarperCollins College Publishers; 1993.
- Martin DF. Pathomechanics of knee osteoarthritis. Medicine and Science in Sports and Exercise. 1994; 26: 1429-1434.
- Michet CJ. Osteoarthritis. Primary Care. 1993; 20: 815-826.
- Nicholas J, Hershman E. The Lower Extremity and Spine In Sports Medicine. St. Louis, MO: Mosby-Year Book; 1986.
- Physiome Project. 2003. Retrieved from: http://www.physiome.org.nz/sites/physiome/anatml/database/knee/ groups/group_12.html.
- Rasch PJ. Kinsiology and Applied Anatomy. 7th ed. Philadelphia, PA: Lea & Fehiger.
- Sieg KW, Adams AP. Illustrated Essentials of Musculoskeletal Anatomy. 2nd ed. Gainesville, FL: Megabooks; 1985.
- Smilli IS. Injuries of the Knee Joint. UCLA BIOMED WE 870 S641i; 1951.
- Whiting WC, Zernicke RF. Biomechanics of Musculoskeletal Injury. Champaign, IL; Human Kinetics; 1985.
- Wilkerson G. Conservative Management of Osteoarthritis (FN: 97-158). Shirley, NY: Biodex Medical Systems; 1997.
*Figures 6, 7, and 8 are based on diagrams originally printed in Arnhein DD, Prentice WE. Principles of Athletic Training. 8th ed. St. Louis, MO: Mosby Year Book;1993.
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Matthew Donohoe holds a bachelor’s degree in kinesiology with an emphasis In athletic training, and a master’s degree in physical education with an emphasis in biomechanics and athletic training. He has by the National Athletic Trainers Association. Donohoe’s studies and professional experience have focused on accident reconstruction, biomechanics, athletic training, and injury rehabilitation. He has assisted in research projects at San Diego State University’s Biomechanics Lab and has developed and carried out the protocol for research investigations on osteoarthritis knee bracing. Donohoe lectures on biomechanics as it relates to low-speed automobile accidents and daily life activities, and has carried out research on forces generated by sporting activities and activities of daily living. Currently Donohoe utilizes his knowledge of accident reconstruction, biomechanics, and the mechanics of injury at the Institute of Risk & Safety Analyses to determine the potential for injury in a given accident.
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Helen Aslanian obtained a bachelor’s degree in physics from the University of California, Los Angeles (UCLA) in 2001 and is currently working on a master’s degree in engineering at UCLA. Her experience includes an internship at Boeing’s Electron Dynamics Division, and her professional responsibilities have included assessing and studying products and engineering laboratory processes to create a detailed, web-interface database.
As an undergraduate student at UCLA, Aslanian co-authored and presented papers based on her research on solid-state physics. Her research included laboratory work on, and analysis of, superconducting materials at the National High Magnetic Field Laboratory in Florida. Today Aslanian applies her understanding of a broad range of physics and her background in analysis and problem solving to the field of accident reconstruction at the Institute of Risk & Safety Analyses.
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Dr. Kenneth Solomon obtained a bachelor’s, master’s, and doctorate degree in engineering and a postdoctorate degree in risk benefit assessment from UCLA. He also holds a professional engineering license. Dr. Solomon's studies are limited primarily to accident reconstruction, biomechanics, and risk-benefit assessment, as demonstrated by his 29 years of independent research; his more than 200 internationally distributed publications, reports, and presentations; the three books he co-authored; and his journal guest editorships. In December of 1998 and after over 22 years of service, he retired as Senior Scientist with the RAND Corporation. He was on the faculty at the RAND Graduate School for 18 years and has taught as an adjunct faculty member at UCLA, the University of South Carolina, the Naval Post-Graduate School, and George Mason University. Dr. Solomon is a reserve deputy level IV with the Orange County Sheriff-Coroner’s Department. He is also Commissioner of the Policing Commission for the City of Calabasas. He has published studies on transportation accidents (involving automobiles, trucks, motorcycles, and bicycles), industrial and recreational accidents (involving pressure vessels; rotating machinery; forklifts and cranes; exercise, gym, and recreational equipment; swimming pools; and manufacturing and punch presses), slip-and-fall and trip- and-fall accidents, and the adequacy of warnings.
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