Electromyographic Activities of the Rotator Cuff Muscles During Walking, Eating, and Washing.

OBJECTIVE: The aim of this study was to evaluate the activity of rotator cuff (RC) muscles during activities of daily living. DESIGN: Motion analysis was conducted with 14 volunteers. Activation of RC (subscapularis, supraspinatus, and infraspinatus) was assessed using electromyography (EMG). Walking was performed with or without a shoulder immobilizer. Eating was conducted with or without the support of the elbow with the contralateral hand. Washing the hair was simulated while standing or leaning forward; washing the body was simulated while standing or holding the elbow; and washing the face was simulated using both hands while leaning forward. RESULTS: During walking, RC's peak EMG activities remained below 7% maximum voluntary isometric contraction at all times, regardless of the use of immobilizers. Eating caused mild EMG activities (14%-32%), whereas eating with elbow support resulted in significantly lower EMG activities in the supraspinatus and infraspinatus. Washing the hair standing moderately activated RC (23%-57%), whereas leaning forward decreased it to 6% to 36%. Washing the body while holding the elbow decreased infraspinatus activation to 4% from 10% when standing. Washing the face with both hands and leaning forward resulted in high-peak EMG activities in the upper subscapularis (37%). CONCLUSIONS: There was no difference in RC activity level between walking with or without immobilizers. From the point of muscle contraction, an immobilizer is not mandatory. Holding the elbow with the contralateral hand while eating or washing can help decrease the load in the supraspinatus and infraspinatus.

Osteoarthritis of the second metatarsophalangeal joint associated with hallux valgus deformity.

BACKGROUND: Hallux valgus is speculated to increase the load on the second metatarsophalangeal (MTP) joint, possibly inducing degenerative osteoarthritis. In addition, the severity of arthritis may be correlated with the severity of hallux valgus. This study evaluated the association of arthritis of the second MTP joint in hallux valgus patients and the relationship between arthritis of the second MTP joint and hallux valgus deformity. METHODS: A total of 382 patients (509 feet) underwent surgery for symptomatic hallux valgus deformities by the 2 senior authors (KTL, YUP) from November 2011 to December 2012. A total of 54 patients (61 feet), all female, were included in the osteoarthritis (OA) group. The rest were assigned to the nonosteoarthritis (NOA) group. There were 328 patients (448 feet) consisting of 16 men and 432 women. Osteoarthritis patients were then evaluated and classified according to joint space narrowing (JSN) and osteophyte (OP) formation. A statistical analysis was conducted to compare the 2 groups in terms of their hallux valgus angle (HVA), intermetatarsal angle (IMA), distal metatarsal articular angle (DMAA), hypermobility of the first metatarsal ray, the length of the second metatarsal bone, and the length ratio of the first and second metatarsal bones. Correlation coefficients were calculated to compare the severity of hallux valgus and the degree of osteoarthritis of the second MTP joint. RESULTS: The IMA of the OA group was 16.2 ± 2.9 degrees, and that of the NOA group was 15.4 ± 3.3 degrees (P = .034, Mann-Whitney U test). The DMAA of the OA group was 18.2 ± 8.3 degrees, and that of the NOA group was 16.1 ± 8.0 degrees (P = .029, Mann-Whitney U test). There were no significant differences between the 2 groups in terms of the HVA, hypermobility, the length of the second metatarsal bone, and the length ratio of the second and first metatarsal bones. In the OA group, there was a positive correlation between the HVA and the degree of osteoarthritis (osteophyte formation) (É£ = 0.278, P = .030). In addition, there was a positive correlation between the IMA and the degree of osteoarthritis (É£ = 0.284 [JSN], 0.327 [OP] for the HVA, P = .026 [JSN], .010 [OP]). However, there was no significant difference between hypermobility and the degree of osteoarthritis (P = .356 [JSN], .635 [OP], Mann-Whitney U test). Furthermore, there were no positive correlations between the DMAA, the length of the second metatarsal bone, and the metatarsal length ratio. CONCLUSION: Our study demonstrated a positive correlation between HVA, IMA, and osteoarthritis of the second MTP joint. Other studies will be needed to determine the factors that are responsible for this correlation. LEVEL OF EVIDENCE: Level III, retrospective comparative series.