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Knee instability or pain-related reflexes in buckling, giving way, or giving out?
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Samuel Betts, PT, DPT, MOMT, FAAOMPT , Alfonse T. Masi, MD, DR. P.H.
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SBetts{at}midwest-ortho.com Samuel Betts, PT, DPT, MOMT, FAAOMPT, et al.
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Knee instability may present symptomatically as buckling, giving way, or giving out, and is often associated with rupture of the anterior cruciate ligament. Collateral ligament sprains may cause medial or lateral knee instability and buckling (1). Proposed mechanisms include ligamentous defects (1), thigh muscle atrophy or fatigue (1, 2), stretch reflex alterations (3), and knee joint changes, e.g., osteoarthritis (OA) (4). Few studies were performed of knee instability symptoms in the general population, and the report of Felson et al (4) is welcomed. In that community study (4), knee buckling or having given way in a 3 month interval was more frequent in subjects having particular characteristics. Knee instability was more frequent in those having had pain, aching, or stiffness in either knee, over a 30 day interval (14.1 %) vs those responding negatively (2.1 %). Persons having highest body mass index (31.3 + kg/m2 ) had comparably high prevalence of knee symptoms (17.6 %), as did those with a history of knee injury (15.7 %), and greater radiographic evidence of OA (17.7 %). Quadriceps strength was inversely and independently related to the knee symptoms (Table 2, 4). They were also independently associated with worse physical functioning in personal activities and work abilities (4). The recent report (4) is helpful for the physical therapist, internist, and rheumatologist, but a few points deserve clarification for patient management and for future research. Causal inferences or mechanisms cannot be interpreted from a historical or cross-sectional study design (4). However, greater specification of the instability event could help direct management. Giving way with vs without pain may infer mainly pain-related alterations of thigh muscle reflex activation vs biomechanical instability. As indicated (4), muscle strengthening and balance training are advisable to treat biomechanical instability. Pain- related instability may also benefit from such more directed therapy. The terms buckling, giving way, or giving out have not been well defined in medical dictionaries or texts. One orthopedic text (1) described giving way as, “a sudden weakness in the leg that causes the leg to go into mild hyperextension or flexion” (presumably from neutral stance). Symptoms of giving way have also been associated with knee instability and displacements (2, 3, 5). Giving way was attributed to altered stretch reflex excitability, rather than to instability, in one study, without indication of pain symptoms (3). Future standardization of terminology and specification of event circumstances may likely improve data accuracy in future research. References 1. D’Amato M, Bach BR, Jr. Knee injuries. In: Brotzman SB and Wilk KE (eds), clinical orthopedic rehabilitation, 2nd ed, Mosby, Inc. Philadelphia, 2003; Ch 4, 251-370. 2. Melnyk M, Gollhofer A. Submaximal fatigue of the hamstrings impairs specific reflex components and knee stability. Knee Surg Sports Traumatol Arthrosc. 2007; 15: 525-32. 3. Melnyk M, Faist M, Gothner M, Claes L, Friemert B. Changes in stretch reflex excitability are related to “giving way” symptoms in patients with anterior cruciate ligament rupture. J Neurophysiol. 2007; 97: 474-80. 4. Felson DT, Niu J, McClennan C, Sack B, Aliabadi P, Hunter DJ, et al. Knee buckling: prevalence, risk factors, and associated limitations in function. Ann Intern Med. 2007; 147: 534-40. 5. Houck J, Lerner A, Gushue D, Yack HJ. Self-reported giving way episode during a stepping-down task: case report of a subject with an ACL- deficient knee. J Orthop Sports Phys Ther. 2003; 33: 273-82. Samuel J Betts, PT, DPT, MOMT, FAAOMPT Director of Rehabilitation Services Midwest Orthopaedic Center Peoria, IL 61614 Alfonse T Masi, MD, DR.P.H. Professor of Medicine University of Illinois College of Medicine at Peoria Peoria, IL 61656 Conflict of Interest:None declared |
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