Fractures associated with patellar ligament grafts in cruciate ligament surgery. (73/489)

We reviewed retrospectively 490 patellar ligament reconstructions for cruciate ligament injuries performed from 1980 to 1990. There were six cases of patellar splitting and three displaced patellar fractures in donor knees. The fissure fractures all occurred during the removal of the patellar bone block. The displaced fractures were sustained during early rehabilitation, and in two of the three patients, involved the normal contralateral knee. The major reasons for this complication were imprecise saw cuts, spreading osteotomies, and the use of a too large patellar bone block. When a trapezoidal bone block is used to self-lock in the femoral tunnel, this should preferably be taken from the tibia. Special care is needed in rehabilitation when the graft has been taken from the contralateral knee.  (+info)

Tenodesis of the extensor carpi ulnaris for chronic, post-traumatic lunotriquetral instability. (74/489)

We describe a technique of soft-tissue reconstruction which is effective for the treatment of chronic lunotriquetral instability. Part of extensor carpi ulnaris is harvested with its distal attachment preserved. It is passed through two drill holes in the triquetrum and sutured to itself. This stabilises the ulnar side of the wrist. We have reviewed 46 patients who underwent this procedure for post-traumatic lunotriquetral instability with clinical signs suggestive of ulnar-sided carpal instability. Standard radiographs were normal. All patients had pre-operative arthroscopy of the wrist at which dynamic lunotriquetral instability was demonstrated. A clinical rating system for the wrist by the Mayo clinic was used to measure the outcome. In 19 patients the result was excellent, in ten good, in 11 satisfactory and in six poor. On questioning, 40 (87%) patients said that surgery had substantially improved the condition and that they would recommend the operation. However, six (13%) were unhappy with the outcome and would not undergo the procedure again for a similar problem. There were six complications, five of which related to pisotriquetral problems. The mean follow-up was 39.1 months (6 to 100). We believe that tenodesis of extensor carpi ulnaris is a very satisfactory procedure for isolated, chronic post-traumatic lunotriquetral instability in selected patients. In those with associated pathology, the symptoms were improved, but the results were less predictable.  (+info)

Knee ligament mechanical properties are not influenced by estrogen or its receptors. (75/489)

Women are at greater risk of tearing their knee anterior cruciate ligament (ACL) than men participating in similar athletic activities. There is currently no conclusive explanation for this disparity; however, as ACL injuries in women have been linked with estrogen fluctuations during the menstrual cycle, one hypothesis is that estrogen has a direct detrimental effect on knee ligament mechanical properties. This study investigated the influence of estrogen and its receptors (ER alpha and ER beta) on knee ligament mechanical properties. This was achieved by testing the viscoelastic and tensile mechanical properties of knee medial collateral ligaments (MCL) and ACLs from: 1) male Sprague-Dawley rats treated with either estrogen (17alpha-ethynylestradiol; 0.03 mg/kg) or an ER alpha-specific agonist (propyl pyrazole triol; 2 mg/kg), and 2) female mice with a null mutation of the gene encoding for ER beta. Estrogen treatment had no significant effects on the viscoelastic or tensile mechanical properties of the rat MCL or ACL. Similarly, pharmacological stimulation of ER alpha using a selective agonist in rats and genetic modulation of ER beta by null mutation of its gene in mice did not influence MCL or ACL properties. These data indicate that estrogen does not have a major direct effect on ligament mechanical properties. Energies for the prevention of the disproportionately high rate of knee ligament injuries in women may be better spent focusing on more established and modifiable risk factors, such as abnormalities in neuromuscular control about the knee.  (+info)

Changes in patterns of scaphoid and lunate motion during functional arcs of wrist motion induced by ligament division. (76/489)

PURPOSE: To determine the in vitro motion of the scaphoid and lunate during wrist circumduction and wrist dart-throw motions and to see how these motions change after the ligamentous stabilizers of the scaphoid and lunate are sectioned in a manner simulating scapholunate instability. METHODS: Twenty-one fresh-frozen cadaver forearms were moved through a dart-throw motion and a circumduction motion using a wrist joint simulator. Scaphoid and lunate motion were measured with the wrist ligaments intact and after sectioning of the scapholunate interosseous ligament, the scaphotrapezium ligament, and the radioscaphocapitate ligament. RESULTS: In the intact wrist the scaphoid and lunate moved more during circumduction than during the dart-throw motion. With ligamentous sectioning the scaphoid flexed more and the lunate extended more during both the circumduction and dart-throw motions. During the circumduction motion both before and after sectioning the global motion of the scaphoid was greater than that of the lunate. After sectioning the scaphoid motion increased and the lunate motion decreased. CONCLUSIONS: The scaphoid and lunate motions were observed to change remarkably after ligamentous sectioning. The observed changes in carpal motion correlate with the clinical observation that after ligamentous injury arthritic changes occur in the radioscaphoid joint and not in the radiolunate joint. Analysis of the injured wrist in positions that combine flexion-extension and radial-ulnar deviation may allow noninvasive diagnosis of specific wrist ligament injuries.  (+info)

Tensile engagement of the peri-ankle ligaments in stance phase. (77/489)

BACKGROUND: Development of reconstructive operative procedures to restore normal ankle kinematics after injury requires an understanding of the biomechanics of the ankle during gait. The contribution of the peri-ankle ligaments to ankle motion control is not yet well understood. Knowledge of the tensile engagement of the peri-ankle ligaments during stance phase is necessary to achieve physiologic motion patterns. METHODS: Eleven fresh-frozen cadaver ankles were subjected to a dynamic loading sequence simulating the stance phase of normal level gait. Simultaneously, ligament strain was continuously monitored in the anterior talofibular, calcaneofibular, and posterior talofibular ligaments, as well as in the anterior, middle, and posterior superficial deltoid ligaments. Eight of these specimens underwent further quasi-static range-of-motion testing, where ligament tension recruitment was assessed at 30 degrees plantarflexion and 30 degrees dorsiflexion. RESULTS: In the dynamic loading tests, none of the ligaments monitored showed a reproducible strain pattern indicating a role in ankle stabilization. However, in the extended range-of-motion tests, most ligaments were taut in plantarflexion or dorsiflexion. CONCLUSIONS: A consistent combination of individual ligament strain patterns that principally control ankle motion was not identified; none of the ligaments studied were reproducibly recruited to be a primary stabilizing structure. The peri-ankle ligaments are likely to be secondary restraining structures that serve to resist motion to avoid extreme positions. Stance phase ankle motion appears to be primarily controlled by articular congruity, not by peri-ankle ligament tension.  (+info)

The elephant knee joint: morphological and biomechanical considerations. (78/489)

Elephant limbs display unique morphological features which are related mainly to supporting the enormous body weight of the animal. In elephants, the knee joint plays important roles in weight bearing and locomotion, but anatomical data are sparse and lacking in functional analyses. In addition, the knee joint is affected frequently by arthrosis. Here we examined structures of the knee joint by means of standard anatomical techniques in eight African (Loxodonta africana) and three Asian elephants (Elephas maximus). Furthermore, we performed radiography in five African and two Asian elephants and magnetic resonance imaging (MRI) in one African elephant. Macerated bones of 11 individuals (four African, seven Asian elephants) were measured with a pair of callipers to give standardized measurements of the articular parts. In one Asian and three African elephants, kinematic and functional analyses were carried out using a digitizer and according to the helical axis concept. Some peculiarities of healthy and arthrotic knee joints of elephants were compared with human knees. In contrast to those of other quadruped mammals, the knee joint of elephants displays an extended resting position. The femorotibial joint of elephants shows a high grade of congruency and the menisci are extremely narrow and thin. The four-bar mechanism of the cruciate ligaments exists also in the elephant. The main motion of the knee joint is extension-flexion with a range of motion of 142 degrees . In elephants, arthrotic alterations of the knee joint can lead to injury or loss of the cranial (anterior) cruciate ligament.  (+info)

Multiple-image radiography for human soft tissue. (79/489)

Conventional radiography only provides a measure of the X-ray attenuation caused by an object; thus, it is insensitive to other inherent informative effects, such as refraction. Furthermore, conventional radiographs are degraded by X-ray scatter that can obscure important details of the object being imaged. The novel X-ray technology diffraction-enhanced imaging (DEI) has recently allowed the visualization of nearly scatter-free images displaying both attenuation and refraction properties. A new method termed multiple-image radiography (MIR) is a significant improvement over DEI, corrects errors in DEI, is more robust to noise and produces an additional image that is entirely new to medical imaging. This new image, which portrays ultra-small-angle X-ray scattering (USAXS) conveys the presence of microstructure in the object, thus differentiating homogeneous tissues from tissues that are irregular on a scale of micrometres. The aim of this study was to examine the use of MIR for evaluation of soft tissue, and in particular to conduct a preliminary investigation of the USAXS image, which has not previously been used in tissue imaging.  (+info)

Posterior subluxation and dislocation of the shoulder in obstetric brachial plexus palsy. (80/489)

We describe the results of surgical treatment in a prospective study of 183 consecutive cases of subluxation (101) and dislocation (82) of the shoulder secondary to obstetric brachial plexus palsy between 1995 and 2000. Neurological recovery was rated 'good' or 'useful' in all children, whose lesions fell into groups 1, 2 or 3 of the Narakas classification. The mean age at operation was 47 months (3 to 204). The mean follow-up was 40 months (24 to 124). The mean gain in function was 3.6 levels (9.4 to 13) using the Mallet score and 2 (2.1 to 4.1) on the Gilbert score. The mean active global range of shoulder movement was increased by 73 degrees ; the mean range of active lateral rotation by 58 degrees and that of supination of the forearm by 51 degrees . Active medial rotation was decreased by a mean of 10 degrees . There were 20 failures. The functional outcome is related to the severity of the neurological lesion, the duration of the dislocation and onset of deformity.  (+info)