The pros and cons of muscle co-contraction in osteoarthritis of the kneeComment on the article by Lewek et al.код для вставкиСкачать
1354 LETTERS patients with early disease, and thus was not designed or powered to be able to address that question. Cecilia P. Chung MD, MPH Annette Oeser, BS Tebeb Gebretsadik, MPH Ayumi Shintani, PhD, MPH C. Michael Stein, MD Vanderbilt University School of Medicine Nashville, TN 1. Pincus T, Summey JA, Soraci SA Jr, Wallston KA, Hummon NP. Assessment of patient satisfaction in activities of daily living using a modified Stanford Health Assessment Questionnaire. Arthritis Rheum 1983;26:1346–53. 2. Prevoo ML, van ‘t Hof MA, Kuper HH, van Leeuwen, van de Putte LB, van Riel PL. Modified disease activity scores that include twenty-eight–joint counts: development and validation in a prospective longitudinal study of patients with rheumatoid arthritis. Arthritis Rheum 1995;38:44–8. 3. Maradit-Kremers H, Nicola PJ, Crowson CS, Ballman KV, Gabriel SE. Cardiovascular death in rheumatoid arthritis: a populationbased study. Arthritis Rheum 2005;52:722–32. 4. Turesson C, McClelland RL, Christianson TJ, Matteson EL. No decrease over time in the incidence of vasculitis or other extraarticular manifestations in rheumatoid arthritis: results from a community-based study. Arthritis Rheum 2004;50:3729–31. DOI 10.1002/art.21781 The pros and cons of muscle co-contraction in osteoarthritis of the knee: comment on the article by Lewek et al To the Editor: In a recent issue, Lewek et al presented a study on co-contraction of antagonist muscles of the upper and lower leg in patients with osteoarthritis (OA) of the knee (1). Their main findings are that patients with OA have higher levels of co-contraction than healthy controls, and that better knee stability correlates positively with higher co-contraction in patients with OA. The authors then suggest that the higher level of co-contraction needs to be counteracted because of the risk of increased disease progression. In our opinion, such an approach could be detrimental to the functioning of patients with OA. Co-contraction of antagonist leg muscles in subjects with unstable knees has been reported previously. Doorenbosch and Harlaar showed that there is increased cocontraction in patients with lesions of the anterior cruciate ligament as compared with healthy control subjects (2). Likewise, differences in muscle activity patterns, including significant increases in co-contraction, have been reported during walking in patients with OA of the knee when compared with age- and sex-matched controls (3,4). We believe that Lewek et al rightly conclude that antagonist muscle co-contraction is used to stabilize the knee joint in the absence of adequate stabilization by the passive restraint system (ligaments and capsule) of the knee. Furthermore, we have found evidence that, in the absence of adequate stabilization by the passive restraint system, muscle activity becomes even more important in maintaining walking ability in knee OA (manuscript submitted). Thus, co-contraction seems to enhance stability of the knee joint and consequently walking ability in knee OA. We do not agree with the suggestion by Lewek et al that co-contraction needs to be counteracted. First, the chain of effects starting with muscle co-contraction and resulting in progression of OA through an increase in intraarticular compression is as yet hypothetical and needs to be confirmed empirically. Second, there is evidence that counteracting the process of co-contraction will decrease the stability of the knee and thereby reduce walking ability. Based on the current evidence, counteracting co-contraction is not a sound therapeutic option. On the contrary, there is ample evidence that enhancing muscle function through exercise therapy is effective in reducing pain and disability in knee OA (5). Martijn Steultjens, PhD Joost Dekker, PhD Jan van Breemen Institute Vu University Medical Centre Martin van der Esch Jan van Breemen Institute Amsterdam, The Netherlands 1. Lewek MD, Ramsey DK, Snyder-Mackler L, Rudolph KS. Knee stabilization in patients with medial compartment knee osteoarthritis. Arthritis Rheum 2005;52:2845–53. 2. Doorenbosch CA, Harlaar J. A clinically applicable EMG-force model to quantify active stabilization of the knee after a lesion of the anterior cruciate ligament. Clinical Biomech (Bristol, Avon) 2003;18:142–9. 3. Childs JD, Sparto PJ, Fitzgerald GK, Bizzini M, Irrgang JJ. Alterations in lower extremity movement and muscle activation patterns in individuals with knee osteoarthritis. Clinical Biomech (Bristol, Avon) 2004;19:44–9. 4. Hortobagyi T, Westerkamp L, Beam S, Moody J, Garry J, Holbert D, et al. Altered hamstring-quadriceps muscle balance in patients with knee osteoarthritis. Clinical Biomech (Bristol, Avon) 2005;20: 97–104. 5. Fransen M, McConnell S, Bell M. Therapeutic exercise for people with osteoarthritis of the hip or knee: a systematic review. J Rheumatol 2002;29:1737–45. DOI 10.1002/art.21775 Reply To the Editor: We thank Dr. Steultjens and colleagues for their comments on our study of knee stabilization in patients with medial compartment knee osteoarthritis (OA), and welcome the invitation to emphasize some key points relating to our work that may be misconstrued by readers of the article. We agree with the assertion that muscle activity is vital to joint stability, particularly when passive restraints are compromised, such as in people with anterior cruciate ligament (ACL) deficiency and knee OA. However, we do not feel that muscle co-contraction, as we define it, is always beneficial in either population.