(1/489) Anterior instability of the glenohumeral joint with humeral avulsion of the glenohumeral ligament. A review of 41 cases.
We studied retrospectively a consecutive series of 547 shoulders in 529 patients undergoing operation for instability. In 41, the cause of instability was considered to be lateral avulsion of the capsule, including the inferior glenohumeral ligament, from the neck of the humerus, the HAGL lesion. In 35, the lesion was found at first exploration, whereas in six it was noted at revision of a previous failed procedure. In both groups, the patients were older on average than those with instability from other causes. Of the primary cases, in 33 (94.3%) the cause of the first dislocation was a violent injury; six (17.4%) had evidence of damage to the rotator cuff and/or the subscapularis. Only four (11.4%) had a Bankart lesion. In patients undergoing a primary operation in whom the cause of the first dislocation was a violent injury, who did not have a Bankart lesion and had no suggestion of multidirectional laxity, the incidence of HAGL was 39%. (+info)
(2/489) Injury and reconstruction of the anterior cruciate ligament and knee osteoarthritis.
OBJECTIVE: The objective of this study was to study injury and reconstruction of the anterior cruciate ligament (ACL) and their effects on knee osteoarthritis. DESIGN: This manuscript discusses the function of knee ligaments, including the basic mechanical properties, the structural properties of their respective bone-ligament-bone complexes, as well as their time- and history-dependent viscoelastic characteristics. The in-situ forces in the ACL and its replacement grafts and knee kinematics before and after ACL reconstruction are also examined. RESULTS: A robotic/universal force-moment sensor (UFS) testing system has been developed which offers a unique method in determining the multiple-degree of freedom knee kinematics and in-situ forces in human cadaveric knees. Under a 110 N anterior tibial load we found at flexion angles of 15 degrees or lower, there was a significantly larger in-situ force in the PL bundle (approximately 75 N) of the ACL as compared to the AM bundle (approximately 35 N)(P < 0.05). We also found that a quadruple semitendinosus and gracilis tendon ACL graft may be better at fully restoring in-situ forces for the whole range of knee flexion when compared to a bone-patellar tendon-bone ACL graft. CONCLUSIONS: The robotic/UFS testing system allows us to determine knee kinematics and the in-situ forces in cadaveric knees in a non-invasive, non-contact manner. Additionally, the ability to reproduce kinematics during testing allows us to evaluate ACL and ACL graft function under external and simulated muscle loading conditions. Finally, we can also examine many of the variables of ACL reconstructions that affect knee kinematics and graft forces including graft tensioning, graft type, graft placement and tibial positioning during graft fixation. (+info)
(3/489) Changes in biomechanical properties of tendons and ligaments from joint disuse.
OBJECTIVE: The purpose of this paper is to review changes in the biomechanical properties of tendons and ligaments from joint disuse. METHOD: We have reviewed 37 experimental studies on joint disuse, which have been carried out with various models of disuse and with various animals. RESULTS: Immobilization of joints has most commonly been used as a model of disuse. Immobilization of the joint deteriorates the mechanical properties of tendons and ligaments, and reduces their cross-sectional area, although there are some differences in the speed of deterioration among tissues. Remobilization returns the mechanical properties once reduced by immobilization to nearly normal quickly, although the structural properties of the bone-ligament-bone complex continue to lag behind those of the controls. Stress deprivation has been regarded as an essential causative factor in joint disuse. Even if joint motion is allowed, stress deprivation rapidly reduces the mechanical properties of the tendon and ligament tissues, and increases the cross-sectional area of them. These effects appear time- and dose-dependent. Restressing increases the mechanical properties once reduced by stress deprivation, although it takes much time to completely recover them. The reduction of the ultimate stress may be explained by the reduction of the total area of collagen fibrils in tendon cross-section and the increase of thin and immature fibrils. (+info)
(4/489) Molecular biology and biomechanics of normal and healing ligaments--a review.
OBJECTIVE: In this review article, we discuss current data and concepts concerning the molecular biology and biomechanics of both normal and healing ligaments in a rabbit model. METHOD: Data is presented from light microscopy, transmission electron microscopy, molecular biology (RT-PCR), and biomechanical measurements (laxity, stress at failure, modulus, and static creep) or normal, pregnant and healing rabbit medial collateral ligaments. RESULTS: 'Flaws' in scar matrix, smaller-than-normal diameter collagen fibrils, and failure of collagen cross-link maturation may be particularly important deficiencies which appear to be related to ligament scar weakness and perhaps to scar creep. The mechanical behaviours of both normal and healing ligaments are altered by relative states of joint motion and normal ligaments are affected by systemic hormones (particularly during pregnancy). DISCUSSION: Molecular analysis of ligaments and ligament scars, combined with ongoing morphological and biomechanical studies of ligament structure and function, will ultimately reveal which factors can be manipulated clinically to optimize the restoration of normal ligament properties after ligament injuries. Further studies on the mechanisms of ligament healing, genetic markers of repair, and gender-specific differences in ligament repair responses are required. (+info)
(5/489) The wrist of the formula 1 driver.
OBJECTIVES: During formula 1 driving, repetitive cumulative trauma may provoke nerve disorders such as nerve compression syndrome as well as osteoligament injuries. A study based on interrogatory and clinical examination of 22 drivers was carried out during the 1998 formula 1 World Championship in order to better define the type and frequency of these lesions. METHODS: The questions investigated nervous symptoms, such as paraesthesia and diminishment of sensitivity, and osteoligamentous symptoms, such as pain, specifying the localisation (ulnar side, dorsal aspect of the wrist, snuff box) and the effect of the wrist position on the intensity of the pain. Clinical examination was carried out bilaterally and symmetrically. RESULTS: Fourteen of the 22 drivers reported symptoms. One suffered cramp in his hands at the end of each race and one described a typical forearm effort compartment syndrome. Six drivers had effort "osteoligamentous" symptoms: three scapholunate pain; one medial hypercompression of the wrist; two sequellae of a distal radius fracture. Seven reported nerve disorders: two effort carpal tunnel syndromes; one typical carpal tunnel syndrome; one effort cubital tunnel syndrome; three paraesthesia in all fingers at the end of a race, without any objective signs. CONCLUSIONS: This appears to be the first report of upper extremity disorders in competition drivers. The use of a wrist pad to reduce the effects of vibration may help to prevent trauma to the wrist in formula 1 drivers. (+info)
(6/489) The popliteofibular ligament. An anatomical study of the posterolateral corner of the knee.
We designed an experimental study to prove the existence of the popliteofibular ligament (PFL) and to define its role in providing static stability of the knee. We also examined the contribution of the lateral collateral ligament (LCL). We found this ligament to be present in all eight human cadaver knees examined. These specimens were mounted on a specially designed rig and subjected to posterior, varus and external rotational forces. We used the technique of selective sectioning of ligaments and measured the displacement with a constant force applied, before and after its division. We recorded the displacement in primary posterior translation, coupled external rotation, primary varus angulation and primary external rotation. Statistical analysis using the standard error of the mean by plotting 95% confidence intervals, was used to evaluate the results. The PFL had a significant role in preventing excessive posterior translation and varus angulation, and in restricting excessive primary and coupled external rotation. Isolated section of the belly of popliteus did not cause significant posterolateral instability of the knee. The LCL was also seen to act as a primary restraint against varus angulation and secondary restraint against external rotation and posterior displacement. Our findings showed that in knees with isolated disruption of the PFL stability was restored when it was reconstructed. However in knees in which the LCL was also disrupted, isolated reconstruction of the PFL did not restore stability. (+info)
(7/489) Extensor carpi radialis brevis. An anatomical analysis of its origin.
We studied the origin of extensor carpi radialis brevis using 40 fresh frozen human cadaver specimens. Ten were stained with haematoxylin and eosin and trichrome which showed the collagenous structure of the extensor tendons at their origin. Gross anatomical observation showed that there was no definitive separation between brevis and communis at the osseotendinous junction. The histological findings confirmed the lack of separation between the two tendons. The extensor tendons were in close proximity to the joint capsule but trichrome staining showed no interdigitation of the tendon with the capsule. The validity of ascribing the pain of lateral epicondylitis to extensor carpi radialis brevis must be questioned. It appears to arise more from the 'common extensor' origin. (+info)
(8/489) Acute knee injuries: use of decision rules for selective radiograph ordering.
Family physicians often encounter patients with acute knee trauma. Radiographs of injured knees are commonly ordered, even though fractures are found in only 6 percent of such patients and emergency department physicians can usually discriminate clinically between fracture and nonfracture. Decision rules have been developed to reduce the unnecessary use of radiologic studies in patients with acute knee injury. The Ottawa knee rules and the Pittsburgh decision rules are the latest guidelines for the selective use of radiographs in knee trauma. Application of these rules may lead to a more efficient evaluation of knee injuries and a reduction in health costs without an increase in adverse outcomes. (+info)