摘要:

AbstractIn this study, the short‐term effects of immobilization on joint damage and medial collateral ligament (MCL) healing were investigated in unstable, anterior cruciate ligament (ACL)‐deficient knees in rabbits. Forty‐six 12‐month‐old female New Zealand white rabbits were separated into three groups. Animals from each group had surgery on their right knees: group I, sham controls (n= 9); group II, complete transection of the ACL and removal of a 4 mm segment (gap injury) of MCL midsubstance with no immobilization of the limb (n= 19); and group III, same injuries to the ACL and MCL (as group II) but with immobilization of the limb (n= 18). No surgical repair of disrupted ligaments was performed. Left knees served as unoperated contralateral controls. All animals were allowed unrestricted cage activity until sacrifice in subgroups at 3, 6, and 14 weeks of healing when biomechanical properties of all MCLs were measured. All knee joints were systematically examined for gross evidence of damage to articular cartilage, menisci, and periarticular soft tissues. To monitor relative in vivo loads on injured limbs during healing, hind‐limb weight bearing was assessed at biweekly intervals. Results indicate that animals in both groups II and III bore relatively lower loads (compared to preinjury values) on their injured hindlimbs. Mechanical testing of MCLs showed only minor changes in sham controls, while group II and III healing MCLs demonstrated significantly lower force and stress at MCL complex failure compared to contralateral controls. In specific comparisons of group III to group II animals, we noted that immobilization prevented joint damage over the early intervals studied. In addition, immobilization resulted in MCL laxity similar to contralateral control values but inhibited development of structural strength and stiffness in healing MCLs. These results suggest that in the rabbit, short‐term immobilization of an ACL‐deficient knee offers some advantages to the joint and to certain low load behaviors of the healing MCL, but it also results in a smaller quantity of scar tissue that is less able to resist higher loads. Longer‐term studies involving remobilization are necessary before the effects of brief immobilization on joint damage and MCL healing in this ACL‐deficient model c

ISSN:0736-0266    

DOI:10.1002/jor.1100100202

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractStrain within the anteromedial bundle (AMB) of the anterior cruciate ligament (ACL) was measured in 13 human knee specimens in order to determine the combination of external loads most likely to cause injury. Using a load application system that allowed 5dfwith the flexion angle being fixed, pure loads of anterior/posterior force, medial/lateral force, varus/valgus torque, and internal/external axial torque were applied at three flexion angles: 0°, 15°, 30°. Combined loads were applied in pairs at two flexion angles: 0° and 30°. Liquid mercury strain gauges were used to measure strain in the ACL. Anterior tibial force was the primary determinant of strain in the anteromedial bundle. This strain was significantly larger at 30° flexion than at 0°. The strain sensitivity of the AMB to medial force was approximately one‐half that to pure anterior force. The effect of anterior and medial forces was additive when applied in combination. Neither pure axial torque nor pure varus/valgus torque was observed to strain significantly the AMB at any of the flexion angles investigated. However, valgus torque in combination with anterior force resulted in a significantly larger strain than pure anterior force. Internal axial torque in combination with anterior force also resulted in a larger strain than pure anteri

ISSN:0736-0266    

DOI:10.1002/jor.1100100203

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractWe wished to determine the optimal tensions required to restore normal joint laxity to anterior cruciate ligament (ACL)‐deficient knees using a braided polyethylene ACL prosthesis (PACL). In 10 cadaveric specimens, we measured the anteroposterior (AP) laxity of the intact knee at 10°, 30°, 60°, and 90° of flexion. The ACL was then removed and replaced with the PACL using tunnel‐tunnel (T‐T) and “over‐the‐top” (OTT) placement techniques. In both positions, the PACL was initially tensioned to 0, 9, 18, and 27 N with the knee flexed to 30°. AP joint laxity was then measured at each flexion angle. With an increase in initial tension, there was a corresponding decrease in AP laxity. At 30° and 90° of flexion, AP laxity was not significantly different from normal using T‐T placement and an initial tension of 0 N. At 90° of flexion, AP laxity was not signifincantly different from normal using OTT placement at 0 or 9 N of initial tension. For both positions, all other tension levels and flexion angles constrained AP laxity. No laxity differences were detected between the OTT and T‐T positions at any flexion angle. The variability in AP laxity of the T‐T position was significantly greater than OTT. With a 150‐N anterior shear force applied to the proximal tibia, the maximum tensions developed in the PACL were not significantly different between the two positions except at 90°. The results suggest that implantation of the PACL is best performed using OTT positioning with an initial tension of 0 N

ISSN:0736-0266    

DOI:10.1002/jor.1100100204

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractThe tensile properties of the inferior glenohumeral ligament have been determined in 16 freshly frozen cadaver shoulders. The inferior gleno‐humeral ligament was divided into three anatomical regions: a superior band, an anterior axillary pouch, and a posterior axillary pouch. This yielded 48 bone‐ligament‐bone specimens, which were tested to failure in uniaxial tension. The superior band was consistently the thickest region, averaging 2.79 mm. The thickness of the inferior glenohumeral ligament decreased from antero‐superiorly to postero‐inferiorly. The resting length of all three anatomical regions was not statistically different. Total specimen strain to failure for all bone‐ligament‐bone specimens averaged 27%. Variations occurred between the three regions, with the anterior pouch specimens failing at a higher strain (34%) than those from the superior band (24%) or the posterior pouch (23%). Strain to failure for the ligament midsubstance (11%) was found to be significantly less than that for the entire specimen (27%). Thus, larger strain must occur near the insertion sites of the inferior glenohumeral ligament. Stress at failure was found to be nearly identical for the three regions of the ligament, averaging 5.5 MPa. These values are lower than those reported for other soft tissues, such as anterior cruciate ligament and patellar tendon. The anterior pouch was found to be less stiff than the other two regions, perhaps suggesting that it is composed of more highly crimped collagen fibers. Three failure sites were seen for the inferior glenohumeral ligament: the glenoid insertion (40%), the ligament substance (35%), and the humeral insertion (25%). In addition, significant capsular stretching occurred before failure, regardless of the

ISSN:0736-0266    

DOI:10.1002/jor.1100100205

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractWe describe a photographic method that we have found useful for studying small strain fields within a larger zone of interest. We have used this method to document differences in material properties which correlate with zones of different biochemical makeup in the canine flexor digitorum profundus tendon. This method may be useful in analysis of experimental injury and wound healing in this model and may have application in evaluating material properties of soft tissue in other models as well.

ISSN:0736-0266    

DOI:10.1002/jor.1100100206

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractHydration, fixed charge density, (FCD) and hydration under various osmotic pressures were compared in young, old, and young diabetic sand rats. This rat is a desert animal that may develop diabetes when fed a regular diet; it is also known to have radiographic and histologic evidence of intervertebral disc (IVD) disease. Forty‐five rats and 180 IVD were used in this study; they were divided into three equal groups: young healthy, old healthy, and young diabetics. IVD, cancellous bone, and muscle were sampled from distal lumbar spines. The young diabetic rats (YD) were considerably heavier than the age‐matched controls, had higher insulin and glucose levels, and all YD had cataracts. The discs of the young diabetic animals demonstrated decreased hydration, FCD and ability to resist compression under osmotic pressures as compared with the young and healthy discs and were more similar to the discs from old rats. The IVD is the most affected musculoskeletal connective tissue in sand rats with aging and diabetes. The aged and diabetic discs in the sand rat demonstrated changes similar to human changes with regard to lower hydration, FCD, and ability to resist osmotic pressure. Therefore, the sand rat may be a suitable animal model for studying the pathogenesis of disc degenerat

ISSN:0736-0266    

DOI:10.1002/jor.1100100207

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractSpinal mobility and posture were measured in 294 8‐16‐year‐old boys and girls, divided into five age groups. The upper thoracic sagittal alignment was more vertical among girls, but the postural curves showed no significant age‐related differences for either sex. Among both boys and girls thoracic extension, lateral flexion, and rotation decreased significantly between the ages of 12 and 13, but with the exception of extension they returned to the previous level by age 16. Girls were significantly different from boys at 13 years of age. In the thoracic spine, girls had less kyphosis, and were stiffer in forward and lateral flexion, with more rotation to the right than to the left. In the lumbar spine, lateral flexion increased after the age of 10 in both sexes. Between the ages of 8 and 14 lumbar lateral flexion was significantly greater among girls than among boys, whereas extension and rotation was greater only at the ages of 8 and 10 years. With increasing age, a shift from left to right dominance in lumbar lateral flexion was found in gir

ISSN:0736-0266    

DOI:10.1002/jor.1100100208

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractTrunk proprioception was measured in 253 healthy children 7‐18 years of age using infrared markers placed on the back of the head and on the skin over the T1, T8, and S1 spinous processes. The children were tested for their accuracy in sensing return of the head and trunk to a centered, neutral position in the frontal plane. Whole‐body sway was also quantified during 10 s of relaxed standing by measuring mean amplitudes of trunk marker and foot center of pressure (CP) movements. The results show that trunk positioning accuracy improved significantly with age (p = 0.000). Subjects could position their trunk in the frontal plane to within a mean (±SD) of 2.5 (±1.1) and 0.9 (±0.6)± of the neutral position at ages 7 and 18 years, respectively. No statistically significant gender differences were found. At every age trunk positioning accuracy was diminished in the presence of a continuous external trunk moment (equivalent to 0.01 × body weight × height), although not significantly so. Neither mean trunk sway nor CP amplitudes were significantly correlated with age or sex. The overall results suggest that spine decompensation is only abnormal when it exceeds 20 mm in healthy children and ad

ISSN:0736-0266    

DOI:10.1002/jor.1100100209

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractWe wished to determine whether anterior cruciate ligament (ACL) injury caused changes in patterns of activity of individual or groups of muscles that control the knee joint. The electromyographic (EMG) patterns of six muscles in 26 individuals with uninjured knees and 20 individuals with ruptured ACL were studied during free and fast speed walking. A previously developed clustering technique was used for analysis. This technique involves making the Fourier transform of the average linear envelope (LE) of each muscle for each subject and using the amplitude and phases angles of the lower frequency harmonics as features to describe a pattern. These features are then grouped to subdivide the population of EMG patterns into different types. The results of analyses on single muscles showed that there exists a typical or “normal” pattern for each muscle which most uninjured and some injured subjects exhibit as well as several atypical patterns which mostly injured subjects exhibit, and that the atypical patterns are much more evident a fast walking speed. The characteristic of atypical patterns with respect to normal include time shifts in the peak of major phases of activity, the absence of a second phase of activity, and the existence of additional phases of activity. Synergy analysis showed that if one muscle has an atypical pattern, then several do; i.e., ACL injury induces major changes in the control strategy of the knee. The implications are that for rehabilitation programs one must focus on the training and strengthening of more than one muscle, and that for reconstructive procedures the changes in mechanics of the joint can possibly induce a significant change in its control strat

ISSN:0736-0266    

DOI:10.1002/jor.1100100210

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractUntil now, the mechanical properties of the microcalluses that form in human cancellous bone have been unexplained. We measured the micro‐hardnesses of microcalluses in cancellous bone, of the trabeculae within the microcalluses, of the trabeculae adjacent to microcalluses, and of trabeculae lacking microcalluses in a human tibia and femur. We observed no important differences between materials at the four different sites. Because the microhardness of bone is very closely related to its stiffness, this finding indicates that microcalluses are likely to stiffen the trabeculae in which they are formed, even though they may surround unhealed fractures of the cancellous trabecula

ISSN:0736-0266    

DOI:10.1002/jor.1100100211

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY