Adaptation of muscles of the lumbar spine to sudden imbalance in patients with lower back pain caused by military training.

OBJECTIVE: This study aims to investigate the effects of sudden load changes (expected and unexpected imbalance) on the activity of muscles of the lumbar spine and their central motor control strategy in military personnel with or without chronic low back pain (LBP). DESIGN: Bilateral sudden imbalance was examined (2 × 2 factorial design). SETTING: The 117th PLA Hospital, Hangzhou, China PARTICIPANTS: Twenty-one male subjects with lower back pain and 21 male healthy control subjects were active members of the Nanjing Military Region land forces. OUTCOME MEASURES: Independent variables: LBP vs. healthy controls and imbalance anticipation (expected and unexpected imbalance). DEPENDENT VARIABLES: rapid reaction time (RRT) and intensity of rapid reaction (IRR) of bilateral lumbar (L3-L4) erector spinae (ES), lumbar (L5-S1) multifidus (MF), and abdominal external oblique muscles. Results Under expected or unexpected sudden imbalance conditions, subjects with LBP demonstrated significantly greater IRR than healthy controls in ipsilateral and contralateral ES and MF, respectively (P < 0.05 for all). IRR of contralateral ES was significantly larger than that of the ipsilateral ES. A significant group effect of RRT of both ipsilateral and contralateral ES muscles and a significant time expectation effect on RRT of contralateral MF muscles were also observed. RRT of the contralateral ES muscles was significantly lower than that of the ipsilateral ES muscles (P < 0.001). CONCLUSIONS: Sudden imbalance prolonged RRT of selected trunk muscles in patients with chronic LBP. The activation amplitude increased. The results may provide a theoretical basis for a study on the pathogenesis of chronic LBP.

Prevalence of low back pain among soldiers at an army base.

BACKGROUND: Low back pain (LBP) is a major medical and social problem among working populations and is associated with high medical expense, loss of productivity, and disability. The aim of this study is to investigate the prevalence of LBP among soldiers and evaluate the possible causative factors in military training. The results may provide an insight into changes needed in military training that will reduce the occurrence of LBP among soldiers. METHODS: A cross-sectional survey was conducted in a group of young soldiers in China to estimate the prevalence of LBP and evaluate possible causative factors in military training. RESULTS: The survey was distributed to 1659 soldiers, of whom 1624 responded. LBP was reported by 425 of the 1624 (26.2%) soldiers. The prevalence of LBP was higher in the armored force (51.3%) than in the artillery (27.5%) or infantry (11.9%). A multivariate logical regression analysis identified night training, 5 km cross-country race, and grenade-throwing training as military training risk factors for LBP. CONCLUSIONS: The relatively high incidence of LBP among soldiers was related to night training, 5 km racing, and grenade throwing. Modifications in these training methods should enhance the health of recruits and lower the incidence of LBP.

Influence of distal tibiofibular synostosis on ankle function.

OBJECTIVE: To study the influence of distal tibiofibular synostosis on ankle function. METHODS: From October 1998 to October 2004, a total of 281 consecutive patients underwent operations because of ankle fractures or distal fractures of the tibia and fibula. Distal tibiofibular synostosis occurred after operation in 8 patients. The duration of follow-up averaged 20.6 months (14-44 months). The ankle function was assessed on the basis of functional rating system described by Mazur.(1) RESULTS: According to Mazur's ankle evaluation system, 4 patients achieved an excellent result, 2 a good result and 2 a fair result. The dorsiflexion of the synostosis ankle reduced by 8.26 degrees as compared with that of the contralateral ankle, and there was little influence on the plantar flexion. All the patients had a normal gait. CONCLUSION: The distal tibiofibular synostosis after the operation of ankle fractures or distal fractures of the tibia and fibula usually gives rise to few symptoms and needs no specific treatment.

Treatment of displaced radial head fractures by internal fixation with absorbable pins.

OBJECTIVE: To study the effect of internal fixation with absorbable pins on treatment of displaced radial head fractures. METHODS: From May 1999 to May 2004, 16 patients with displaced radial head fractures (Mason types II and III) were treated with internal fixation by absorbable pins. The duration of follow-up averaged 22.6 months (12-58 months). The outcome was assessed on the basis of elbow motion, radiographic findings and the functional rating score delineated by Broberg and Morrey. RESULTS: All fractures healed within 10 months without avascular necrosis of radial head. The mean elbow flexion loss was 15 degrees (0 degrees-35 degrees), and pronation and supination decreased by 10 degrees (0 degrees-30 degrees) on average compared with those of the contralateral elbow. Five patients had an excellent result, 6 a good result, and 3 a fair result according to the criteria of Borberg and Morrey. CONCLUSIONS: Internal fixation with absorbable pins is an effective method in treating displaced radial head fractures. It can maintain the biomechanical stability of forearm, improve the elbow function and avoid second operation.