Narrow Results

Articular capsule tear was common in elbow fractures, but the tissue mechanical environment during the wound repairing was not clear. The objective of this study was to evaluate the effects of different injury conditions on the stability of the elbow through animal experiments and finite element (FE) analysis. Different injury locations and repair conditions were considered in animal experiments: Type Ia (unrepaired anterior capsule), type Ib (repaired anterior capsule), type IIa (unrepaired whole capsule) and type IIb (repaired whole capsule). The elbow valgus angle at 0, 2 and 4 weeks was analyzed, and the tissue stress under different injury conditions (without injury, anterior capsule injury and complete capsule injury) was acquired through a FE model including active behavior of muscle. The maximum valgus angles of repaired elbow were smaller than those of unrepaired elbow. In completely capsule injury, the stress of ulna cartilage altered obviously compared with intact condition, and the peak stress occurred at the flexion angle of 60^∘. The stress was about 1.63 times that of intact state. The joint capsule was significantly more stressed than other ligaments and played an important role in the flexion of the elbow joint. This study could provide some advice for surgeons.

Knee simulation has been used as the primary tool in the estimation of knee flexion–extension levels for many years. This paper discusses the suitability of AdamsView simulation tool for estimating the flexion–extension angles in the knee joint, i.e. three versions namely: 3D reconstructed knee joint, standard artificial knee joint and artificial high flexion knee joint. The high flexion artificial knee joint model reaches a maximum flexion up to 120.2°. Whereas the standard knee Joint gets about 84.6°. However, the 3D reconstructed knee joint was capable of producing 134.4°. Thus the usage of the mechanical simulation tools in the medical applications has been proved once again.

Background: Despite the movement of the thumb carpometacarpal joint has been studied, many unclarified points remain regarding the movement of this joint. The purpose of this study was to evaluate the in vivo kinematics of the thumb carpometacarpal joint during flexion and abduction using computed tomography images.

Methods: The subjects were 9 healthy males. Computed tomography images were obtained in 4 equally-divided positions from maximum extension to maximum flexion, and maximum adduction to maximum abduction of the thumb. A three-dimensional model was constructed from these images, and the models of each position were superimposed with reference to the trapezium. The amount of angular change around the bone axes of first metacarpal bone and rotation axes were evaluated.

Results: We found that the first metacarpal bone showed relatively simple behavior during abduction. However, during flexion, it exhibited a particular movement in which the amount of angular change of the metacarpal bone with respect to the trapezium rapidly increased with deep flexion.

Conclusions: These results suggest that the thumb carpometacarpal joint exhibits a special movement during flexion, especially deep flexion.

Background: The purpose of this study is to investigate the prevalence of neck and low back discomfort and its association with intervertebral angulations of cervical and lumbar during neutral and flexion among aircrews.

Methods: There were 283 subjects participating in this survey. All participants finished one questionnaire each regarding complaints about musculoskeletal symptoms, and three sagittal plane radiographs. The measurements of intervertebral angulations were completed using the Cobb method for lumbar spine and the Harrison posterior tangent method for the cervical spine.

Results: In the questionnaire, 26.5% subjects self-reported neck discomfort and 33.2% subjects self-reported low back discomfort. Based on categorization by self-reported complaints, there was significant decrease in two intervertebral flexion angles of the Discomfort group than those of the Regular group, including C3/C4 and C2/C7. Based on categorization by radiological diagnoses, the abnormal group revealed significant decreases in the regular range of motion from neutral to flexion at C3/C4 segment. Lordotic angles between L1 and L5 were also found to be significantly different between the Discomfort group and the Regular group.

Conclusions: A high prevalence of neck and low back discomfort among the aircrews is revealed and needs more suitable intervention. A certain level of association between spinal discomfort and the intervertebral angulations of the lumbar spine and the cervical spine in aircrews was found when compared to the normal group.