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Background The purpose of this study was to compare knee biomechanics of the replaced limb to the non-replaced limb of total knee replacement (TKR) patients and healthy controls during walking on level ground and on decline surfaces of 5°, 10°, and 15°. Methods Twenty-five TKR patients and 10 healthy controls performed 5 walking trials on different decline slopes on a force platform and an instrumented ramp system. Two analyses of variance, 2 × 2 (limb × group) and 2 × 4 (limb × decline slope), were used to examine selected biomechanics variables. Results The replaced limb of TKR patients had lower peak loading-response and push-off knee extension moment than the non-replaced and the matched limb of healthy controls. No differences were found in loading-response and push-off knee internal abduction moments among replaced, non-replaced, and matched limb of healthy controls. The knee flexion range of motion, peak loading-response vertical ground reaction force, and peak knee extension moment increased across all slope comparisons between 0° and 15° in both the replaced and non-replaced limb of TKR patients. Conclusion Downhill walking may not be appropriate to include in early stage rehabilitation exercise protocols for TKR patients.

Purpose The purpose of this study was to examine the effects of landing on a combined inversion and plantarflexion surface on the ankle kinematics and electromyographic (EMG) activities of medial gastrocnemius (MG), peroneus longus (PL), and tibialis anterior (TA) muscles. Methods Twelve recreational athletes performed five drop landings from an overhead bar of 30 cm height on to three surfaces: a flat surface, a 25° inversion surface, and a combined surface of 25° inversion and 25° plantarflexion. The kinematic variables and integrated EMG (IEMG) of the three muscles were assessed using a one-way repeated measures ANOVA and a 3 × 3 (surface × muscle) ANOVA, respectively ( p Results The IEMG results showed a significant muscle by surface interaction. The flat surface induced higher TA activity than the two tilted surfaces. The inverted surface produced significantly higher inversion peak angle and velocity than the flat surface, but similar PL activity across the surfaces. The MG IEMG, ankle plantarflexion angle, and inversion range of motion were significantly higher for the combined surface compared to the inverted surface. Conclusion These findings suggest that compared to the inversion surface, the combined plantarflexion and inversion surface seems to provide a more unstable surface condition for lateral ankle sprains during landing.

BackgroundNo studies have compared effectiveness of resistance training and Tai Ji exercise on relieving symptoms of knee osteoarthritis (OA). The purpose of the study was to evaluate effects of a 10-week Tai Ji and resistance training intervention on improving OA symptoms and mobility in seniors with knee OA.MethodsThirty-one seniors (60–85 years) were randomly assigned to a Tai Ji program (n = 12), a resistance training program (n = 13), and a control group (n = 6). All participants completed the Western Ontario and McMaster (WOMAC) Osteoarthritis Index and performed three physical performance tests (6-min walk, timed-up-and-go, and timed stair climb and descent) before and after the 10-week intervention.ResultsThe participants in the resistance training group significantly improved on the timed-up-and-go test (p = 0.001), the WOMAC pain sub-score (p = 0.006), WOMAC stiffness sub-score (p < 0.001), and WOMAC physical function sub-score (p = 0.011). The Tai Ji group significantly improved on the timed-up-and-go test (p < 0.001), but not on the WOMAC scores.ConclusionResistance training was effective for improving mobility and improving the symptoms of knee OA. Tai Ji was also effective for improving mobility, but did not improve knee OA symptoms.

Background Short-leg walking boots are a common intervention for acute and chronic lower extremity injury. Few studies have examined the neuromuscular adaptations associated with short-leg walking boots and no previous study has investigated timing characteristics of muscle activation during gait. The purpose of the current study was to examine the timing and amplitudes of muscle activation of the extrinsic ankle musculature during walking in two types of short-leg walking boots. Methods Eleven healthy young adults performed five level walking trials at a self-selected pace in each of three conditions: normal walking, Gait Walker and Equalizer short-leg walking boots. Ground reaction forces were collected from a force platform while surface electromyography (EMG) was collected from the tibialis anterior, peroneus longus and medial gastrocnemius. EMG signals were rectified and smoothed using the root mean squared with a 20-ms smoothing window and were normalized to the largest mean of the normal walking trials. A repeated measures analysis of variance was used to assess the effect of short-leg walking boots on the onset, duration and amplitude of muscle activation. Results Short-leg walking boots were generally associated with earlier onsets of muscle activation and longer durations of muscle activation. However, there was no reduction in EMG amplitude. Conclusion The findings of this study show that the induced alterations in muscle activation patterns may limit the short-leg walking boots.

Osteoarthritis (OA) is the most common form of arthritis. The knee and hip joints are the most common sites for OA, and knee OA is more prevalent than hip OA. Knee OA patients often suffer pain, functional disability, articular cartilage wear and related joint space narrowing. Among U.S. adults, 46.4 million have physician-diagnosed arthritis representing 21.6% of the U.S. population, and 8.3% (17.4 million) had activity limitations attributable to arthritis. It is estimated that by 2030, the number of physician-diagnosed arthritis cases will reach 67 million, and 25 million will have arthritisattributable activity limitations. Although 7.9% of U.S. adults aged 18e44 years have arthritis, this percentage increases to 29.3% and 50.0% for adults between 45 and 64 years and older than 65 years, respectively. Currently, there is no cure for this degenerative disease. The economic and functional impacts of this disease have become an increased burden for society and individuals. The treatment strategies for knee OA often are aimed at reducing pain, improving physical function, decreasing disability, and limiting OA progression. Over the two decades, several national and international medical organizations including the American College of Rheumatology (ACR), European League Against Rheumatology (EULAR), Osteoarthritis Research Society International (OARSI), and National Institute of Health (NIH) have published evidence-based guidelines for the management of knee OA. These guidelines are mostly evidence-based with expert consensus. The treatment recommendations from these guidelines include non-pharmacological and pharmacological therapies, intraarticular injections, and surgical procedures including arthroscopy, osteotomy and total/unicompartmental knee replacement. A combination of pharmacological and non-pharmacological treatments is commonly recommended in clinical practice and is universally recommended in existing guidelines for the management of knee OA. The non-pharmacological therapies commonly include patient education, selfmanagement programs, personalized social support through telephone contact, weight loss (if overweight), aerobic exercise programs, physical therapy, range-of-motion exercises, muscle strengthening, transcutaneous electrical nerve stimulation (TENS), electromagnetic field therapy (EFT), acupuncture, ultrasound, laser, spa, assistive devices for ambulation, patellar taping, the appropriate footwear, lateral-wedged insoles (for genu varum), bracing, occupational therapy, joint protection and energy conservation, and assistive devices for activities of daily living. In earlier guidelines, acupuncture, TENS, EFT, ultrasound, laser, bracing/taping, and footwear and orthotics were not usually recommended as non-pharmacological treatments. Among the non-pharmacological recommendations, patient education, muscle strengthening, aerobic and range of motion exercises and walking aids received the highest support. Chinese acupuncture as a knee OA treatment alternative first appeared in the knee OA guidelines in 2000 and since then, has been included inmore recent recommendations. In an earlier systematic review of OA, it was found that seven of the studies included reported positive results for acupuncture treatment, and six reported non-significant results. The NIH OA working group made the evidence-based conclusion that “the research to date on the efficacy of acupuncture in osteoarthritis is inconclusive but promising”. In a recentmeta-analysis of acupuncture for knee OA, patients receiving acupuncture showed short-term improvements in pain (effect size (ES) 1⁄4 0.96) and function (ES 1⁄4 0.93) as compared to patients in a waitlist control group. However, when compared to a sham control group, acupuncture showed diminished short-term effects on pain (ES1⁄4 0.35) and function (ES1⁄4 0.35). The ES for pain relief was further reduced at 6 months after treatment. In a more recent review of 16 qualified randomized control trials (RCT) for knee OA, it was shown that the external validity was inadequate in the E-mail address: szhang@utk.edu. Peer review under responsibility of Shanghai University of Sport

In the most recent report of injury data on 15 sports from the U.S. National Collegiate Athletic Association (NCAA) Injury Surveillance System over a span of 16 years (1988e2004), ankle ligament sprains were the most common injury. Residual symptoms such as recurrent sprains, pain, instability, and giving way are common after an initial, acute ligament sprain. Chronic ankle instability (CAI) is one of these common problems, and has enjoyed increased interest in the recent literature. However, CAI remains a poorly-defined and understood condition. CAI has been commonly associated with two types of instability, namely mechanical and functional instability. Hertel in 2002 proposed a CAI model that has been very popular (Fig. 1). In this model, CAI is attributed to both mechanical instability and functional instability. Functional instability may be caused by deficits in proprioception, neuromuscular control, postural control, and/or muscular strength. Mechanical instability may be caused by altered mechanics in one or more joints within the ankle complex. Rather than treating these two types of instability independently, this model considers that they are both part of an instability continuum. When both types of instability are present, recurrent ankle sprain occurs. In a recent paper, Hiller et al. proposed a new and updated CAI model that was evolved from Hertel’s original model. In this new model, CAI has a total of seven sub-groups (Fig. 2). In the new model, the triad consists of mechanical instability, perceived instability (instead of functional instability in

Purpose: The purpose of this study was to examine effects of a sport version of a semi-rigid ankle brace (Element) and a soft ankle brace (ASO) on ankle biomechanics and ground reaction forces (GRFs) during a drop landing activity in subjects with chronic ankle instability (CAI) compared to healthy subjects with no history of CAI. Methods: Ten healthy subjects and 10 subjects who had multiple ankle sprains participated in the study as the control and unstable subjects, respectively. The CAI subjects were age, body mass index and gender matched with the control subjects. The arch index and ankle functions of the subjects were measured in a subject screening session. During the biomechanical test session, participants performed five trials of drop landing from 0.6 m, wearing no brace (NB), Element brace and ASO brace. Simultaneous recording of three-dimensional kinematic (240 Hz) and GRF (1200 Hz) data were performed. Results: The CAI subjects had lower ankle functional survey scores. The arch index and deformity results showed greater arch deformity of Element against a static load than in NB and ASO due to greater initial arch position held by the brace. CAI participants had greater eversion velocity than healthy controls. The ASO brace reduced the first peak vertical GRF whereas Element increased 2nd peak vertical GRF. Element brace reduced eversion range of motion (ROM) and peak eversion velocity compared to NB and ASO. In addition, Element reduced dorsiflexion ROM and increased peak plantarflexion moment compared to NB and ASO. Conclusion: Results of static arch measurements and dynamic ankle motion suggest that the restrictions offered by both braces are in part due to more dorsiflexed ankle positions at contact, and higher initial arch position and stiffer ankle for Element. Copyright 2012, Shanghai University of Sport. Production and hosting by Elsevier B.V. All rights reserved.

The rates of reduction of hip replacement (an end-stage treatment of hip OA) were 35.1%, 50.4%, and 38.5%, respectively. These data, combined with the body mass index (BMI) data of the runners, suggest that running reduced OA and hip replacement risk partially due to the lower BMI associated with runners. Furthermore, the study showed that increased running speed, distance, or years of running did not increase OA risk, but seemed to increase risk of hip replacement. The results also demonstrated that running presents no increased risk for OA compared to walking. The author argued that running may decrease OA more than walking due to the larger percentage of runners (89.5%) who exceeded 1.8 MET-h/day compared to walkers (52.8%). However, the study did not report jointspecific OA in the runners. This prospective cohort study has a large sample size, exceeding the number of surveyed runners 10 times compared to the number of runners surveyed in all previous cross-sectional running studies combined. 3 OA risks associated with participation in other vigorous sports are not clearly evidenced and consistent in the literature. A recent systematic review and meta-analysis on the effects of sport activities on OA predictions (hip, knee, and ankle) provide some new insight. 4 The review, which initially identified 1294 studies and included 43 qualified studies according to a pre-defined set of criteria, included studies that had a large variation in the number of participants (16e8000) and duration of the study period (30 monthse40 years). Regarding the relationship between OA and sport activity, 12 papers met the inclusion criteria, including two retrospective cohort studies, two case series studies, seven caseecontrol studies, and one cross-sectional study. Either radiographic or magnetic resonance imaging was used to define OA in most of the studies; questionnaire, physician diagnosis, and selfreported pain and disability were also used in some of the studies. It was reported that participation in team sports was a risk factor for knee OA onset prior to 45 years of age. 5 One study identified participation in soccer as a risk factor for knee OA 6 while another study did not identify it as a risk factor. 7 Females had an increased risk of developing knee OA compared to males when participating in gymnastics or Kung Fu. 8 A caseecontrol study showed that an increased risk of developing knee OA was associated with participation in soccer, ice hockey, and tennis, but not in track and field, skiing, and orienteering. 9 However, after adjustment for knee