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At least 919 records · Page 51Linked to original sources
PubMed2004

New technique for chronic posterolateral instability of the knee: posterolateral reconstruction using the tibialis posterior tendon allograft.

Posterolateral instability of the knee is known as one of the most challenging injuries. Although several procedures have been designed for the posterolateral instability, there is no gold standard management as yet. We present a technique for posterolateral instability of the knee using a tibialis posterior tendon allograft, which reconstructs the lateral collateral ligament and popliteal tendon with its attachment to the tibia. This can correct not only varus, but also external rotary instability.

Absorbable Implants↗
PubMed2006

Arthroscopic Bankart repair in traumatic anterior shoulder instability using a suture anchor technique.

PURPOSE: The purpose of this study was to prospectively evaluate the surgical outcome of arthroscopic Bankart repair via suture anchors in patients with recurrent traumatic anterior shoulder instability with a minimum follow-up of 2 years. METHODS: We included 54 consecutive patients without an osseous Bankart lesion of greater than 25% of the glenoid circumference with a mean age of 25.3 years (range, 16 to 58 years) undergoing arthroscopic Bankart repair via suture anchors for traumatic anterior shoulder instability. The mean follow-up was 3.7 years (range, 2.3 to 5.2 years) at the final follow-up examination. Patients were evaluated prospectively according to the rating scales of Rowe, the American Shoulder and Elbow Surgeons, and Constant and Murley. One patient was lost to follow-up. RESULTS: After 3.7 years, 4 patients had recurrent instability: 3 had redislocated and 1 had recurrent subluxations. Thus the overall redislocation rate was 7.5%. Of the 4 redislocators, 3 had a traumatic onset of the redislocation. All shoulder scores (Rowe, American Shoulder and Elbow Surgeons, and Constant and Murley) revealed highly significant improvements postoperatively. At final follow-up, 85.7% of patients had returned to their preoperative sports level. CONCLUSIONS: Our results in this series demonstrate the efficacy of arthroscopic Bankart repair with suture anchors for the treatment of recurrent traumatic anterior shoulder instability with respect to recurrence rate, range of motion, and shoulder function during a mean follow-up of 3.7 years. LEVEL OF EVIDENCE: Level IV, therapeutic case series.

Adolescent↗
PubMed2005

Chromosome instability in neoplasia: chaotic roots to continuous growth.

Multiple rearrangements of chromosome number and structure are common manifestations of genomic instability encountered in mammalian tumors. In neoplasia, in continuous immortalized growth in vitro, and in animal models, the accumulation of various defects on DNA repair and telomere maintenance machineries, mitotic spindle abnormalities, and breakage-fusion-bridge cycles, deteriorate the precise mitotic distribution of the genomic content, thus producing various types of chromosomal anomalies. These lesions generate tremendous genomic imbalances, which are evolutionary selected, since they force the function of the whole genome towards continuous growth. For more than a century chromosomal rearrangements and aneuploidy in neoplasia have been discussed and a vast number of genes and pathways, directly or indirectly implicated, have been described. In this review, we focus on the biological mechanisms that generate numerical or structural deviations of the normal diploid chromosomal constitution in epithelial neoplasia. There is growing evidence that chromosomal instability is both an epiphenomenon and a leading cause of cancer. We will discuss the roles of genes, chromosome structure, and telomere dysfunction in the initiation of chromosomal instability. We will explore research strategies that can be applied to identify rates of chromosomal instability in a specimen, and the putative biological consequences of karyotypic heterogeneity. Finally, we will re-examine the longstanding hypothesis of the generation of aneuploidy in the context of telomere dysfunction and restoration.

Aneuploidy↗
PubMed2005

AURKA amplification, chromosome instability, and centrosome abnormality in human pancreatic carcinoma cells.

To test the hypothesis that AURKA amplification contributes to pancreatic tumorigenesis by increasing centrosome abnormality and chromosome instability, the current study explored the associations between AURKA amplification, chromosome instability, centrosome abnormality, and the expression of several important proteins that are involved in cell proliferation (Ki-67), cell cycle regulation (p53, p16), and apoptosis (survivin) in 12 human pancreatic carcinoma cell lines. Using fluorescence in situ hybridization (FISH), we observed that 5 of the 12 cell lines had an AURKA amplification index (AI) (percentage of cells with more than three signals) >60%. Both the AURKA AI and the average number of signals per cell (ANSPC) were significantly associated with the copy number of chromosome 9 but not chromosome 17. The AURKA ANSPC was positively associated with the percentage of cells with the centrosome abnormality. Furthermore, centrosome abnormality was significantly associated with the frequency of cells with abnormal nuclei and abnormal mitotic figures, but no direct association was detected between the frequency of centrosome abnormalities and chromosome instabilities. The AURKA AI was also associated with a lower expression of Ki-67, a higher expression of survivin, and the lack of expression of p16. These associations support our hypothesis that AURKA amplification contributes to pancreatic carcinogenesis by increasing chromosome instability and centrosome abnormality.

Aurora Kinase A↗
PubMed2005

The unstable shoulder in arm elevation: a three-dimensional and electromyographic study in subjects with glenohumeral instability.

BACKGROUND: Although an altered scapulohumeral rhythm is believed to be related to some shoulder dysfunctions, there is scarce evidence on the scapulohumeral rhythm and shoulder muscle activation patterns in subjects with glenohumeral instability. METHODS: Six subjects with glenohumeral instability performed arm elevation in trials of 8 successive stationary positions. Kinematics were recorded on each stationary position using a 6 DOF electromagnetic tracking device. Scapular kinematics was analysed by comparison between recorded scapular angles and those estimated by a linear regression model of the scapulohumeral rhythm which served as standard for normality. Surface electromyographic activity was recorded from the upper and lower trapezius, serratus anterior and deltoid. FINDINGS: Differences in the scapulohumeral rhythm were observed between subjects. Significant differences were founded in scapular protraction and spinal tilt. No differences were found in scapular lateral-rotation in all subjects. Activity of the lower trapezius and serratus anterior seem to increase mostly during the second third of arm elevation. INTERPRETATION: In a particular angle of arm elevation, changes in scapular protraction and/or spinal tilt rotation could introduce changes on the alignment of the humeral head and the glenoid, predisposing/contributing to shoulder instability. These kinematics scapular changes are perhaps due to an inadequate muscular activity. RELEVANCE: The results of this study reinforce the relevance of the scapulohumeral rhythm assessment in the rehabilitation of patients with shoulder instability.

Adult↗
PubMed2005

Lack of consensus gene expression changes associated with radiation-induced chromosomal instability.

The relatively high frequency with which ionizing radiation induces genomic instability suggests that a gene mutation occurring after irradiation is an unlikely cause of the phenotype. To search for mechanism(s) of initiation and perpetuation of this instability phenotype, gene expression profiles of clones exhibiting delayed chromosomal instability were analyzed. Microarray analysis using two pools of isogenic radiation-induced chromosomally unstable clones compared to an irradiated but chromosomally stable clone uncovered a set of 68 differentially expressed genes using two methods of analysis. Unexpectedly, all 68 genes were under-expressed relative to the chromosomally stable reference clone. Further analysis of the candidates placed the differentially expressed genes into pathways implicating differential MAP kinase signaling, ubiquitin/proteasome function, DNA repair, cell cycle control, lipid signaling, nucleotide metabolism, and other potentially disrupted pathways. Validation studies using northern and western blotting, and functional assays concluded that although differences in some of these pathways exist, no single gene or molecular pathway was found to be differentially regulated in all of the chromosomally unstable clones tested. Inferred from these data is that there are multiple potential molecular pathways and/or events that maintain the unstable phenotype, and no single expression pattern is linked to instability in the unstable clones analyzed.

Animals↗
PubMed2005

Management of neonatal hip instability and dysplasia.

The diagnosis and treatment of neonatal hip instability and dysplasia is controversial. Different countries have different algorithms and guidelines on which hips should be screened or treated. German speaking countries have introduced universal ultra sound hip screening programmes resulting in relatively high splintage rates in certain centres. Some Scandinavian centres have organised selective screening programmes with serial ultrasound observation of hip instabilities, leading to comparatively low splintage rates. Though most experts would treat clinical hip instability (confirmed by ultrasound evaluation), the natural history and epidemiology of dysplasia is less well understood. The treatment regimes for neonatal dysplasia are varied with wide differences in the rates of splintage. 'Late' dislocation may be secondary to prenatal dislocation (teratogenic), neonatal hip instability or to persistent major dysplasia of the hip. The term 'missed' dislocation should not be used as this suggests negligence on the part of the examiner, when this may not be the case. Which splint to use (rigid or dynamic), at what age, and for how long, are questions currently unresolved as no proper controlled trials have been undertaken. However, a sensible treatment algorithm can be advocated. Complications secondary to splintage are rare, though nerve damage, avascular necrosis of the hip, redislocation and skin problems have been described.

Hip Dislocation, Congenital↗
PubMed2005

Outcome following Bankart repair for shoulder instability 1998-2002 using a subjective patient based shoulder questionnaire (Oxford).

Bankart repair for shoulder instability has been performed by the senior author since 1998. We employ a modification of the technique as described by Rowe et al., using suture anchors but without a coracoid osteotomy. If inferior instability was present this procedure was combined with a capsular shift. We performed a retrospective case note review and postal questionnaire incorporating the Oxford Instability Score (OIS) on all patients. Fifty Bankart repairs were performed in the study period, three patients had further dislocations and three patients had ongoing symptoms of instability. Response rate to the questionnaire was 62%. Mean OIS following primary stabilisation was 21.7 (possible scores from 12-excellent to 60-poor). OIS following Bankart stabilisation of the shoulder has not been previously reported. These results compare favourably to original scores published by Dawson et al. (1999) who included both patients treated by surgery or physiotherapy.

Adult↗
PubMed2005

Distal radioulnar joint instability in distal radius fractures: the role of sigmoid notch and triangular fibrocartilage complex revisited.

The stabilising effects of various structures of the distal radioulnar joint (DRUJ) have been heavily debated. This biomechanical cadaveric study examined the effects of the volar and dorsal lips of the sigmoid notch and the volar and dorsal aspects of the triangular fibrocartilage complex (TFCC) on DRUJ stability. Sequential fractures of the distal radius and sectioning of the TFCC were performed followed by measurements of ulnar translation with the forearm in pronation, neutral and supination. A dorsal lunate facet fracture created instability in pronation. Lunate facet fractures alone did not create instability in other forearm positions. Sectioning of the volar TFCC after loss of the dorsal TFCC by a dorsal lunate facet fracture caused DRUJ instability with the forearm in neutral position. Sectioning of the dorsal TFCC after loss of the volar TFCC due to a volar lunate facet fracture created instability in neutral and pronated positions.

Biomechanical Phenomena↗
PubMed2006

The effect of joint instability on latency and recruitment order of the shoulder muscles.

Several shoulder dysfunctions are generally characterized as Shoulder Impingement Syndrome (SIS). Specifically, glenohumeral instability (GI) has been viewed as a primary cause of SIS in young individuals, mainly in overhead athletics. Past studies have associated GI with modifications in latency, recruitment order and/or EMG activity. However, it is not clear if pain and/or joint instability can account for these observed changes. The aim of this investigation was to analyze the effect of glenohumeral instability on the latencies and recruitment order of the superficial muscles of the glenohumeral and scapulothoracic joints in swimmers without pain symptom. Eight individuals with and eight without history of Shoulder Impingement Syndrome performed bilateral and simultaneous shoulder elevations at three different distances. The shoulder kinematics and EMG activities of glenohumeral and scapulothoracic muscles were registered. Results showed that subjects of both groups performed the task with similar latencies and recruitment order of the muscle activities. We conclude that shoulder instability does not necessarily affect the latencies and recruitment order of the shoulder muscles during the elevation of the shoulder in the scapular plane. Pain and other factors may be involved in the kinematics and electromyographic alterations demonstrated in other experiments.

Adult↗
PubMed2004

Palmar midcarpal instability: the results of treatment with 4-corner arthrodesis.

PURPOSE: Palmar midcarpal instability (PMCI) is one type of nondissociative carpal instability. The optimal treatment for PMCI is uncertain. The purpose of this investigation was to evaluate the results of capitate-lunate-triquetrum-hamate (4-corner) arthrodesis for PMCI. METHODS: Over a 10-year period 8 patients were treated with 4-corner arthrodesis for PMCI. The instability was diagnosed clinically and confirmed with cineradiography. The symptomatic instability began in all patients after a notable trauma; 6 of the patients were injured at work and 2 were injured in a motor vehicle accident. Patients were evaluated at an average of 34 months after surgery. RESULTS: Seven of the 8 patients were satisfied with the surgery and 6 of 8 patients had no pain or mild pain. Both patients injured in motor vehicle accidents returned to all preinjury activities. Four of the 6 workers' compensation patients returned to work, 3 at full duty and 1 in a restricted position. Two patients, both with workers' compensation, did not return to their pre-injury jobs. One had occasional moderate pain and the other had chronic pain. The average wrist flexion/extension arc of motion decreased with surgery from 135 degrees to 75 degrees. The average grip strength increased significantly with surgery from 20 kg to 32 kg; however, grip strength remained significantly lower than the opposite side strength of 54 kg. CONCLUSIONS: Four-corner arthrodesis is a reasonable option for PMCI. Compared with previous reports of soft tissue reconstruction 4-corner arthrodesis may provide a more reliable solution for this difficult problem.

Adult↗
PubMed2006

Arthroscopic debridement and closed pinning for chronic dynamic scapholunate instability.

PURPOSE: For chronic dynamic scapholunate (SL) instability (>3 months after injury) open procedures (capsulodesis, limited intercarpal fusions, tenodesis, SL ligament reconstruction) have become popular in recent years but their long-term results have been suboptimal. We evaluated retrospectively the results of aggressive arthroscopic debridement of the SL ligament to bleeding bone in an effort to induce scar formation and closed pinning of the SL joint in patients unwilling to have an open procedure. METHODS: Eleven patients (mean age, 37 y) presenting with persistent posttraumatic pain and weakness to the wrist were diagnosed with dynamic SL instability (positive Watson scaphoid shift test result, SL gapping on grip-view radiographs, arthroscopic findings of a Geissler grade III or IV SL tear) and treated. Range of motion, grip strength, radiographic measurements, and the Mayo wrist score were used to evaluate the results. RESULTS: The mean follow-up period was 33 months (range, 12-76 mo). Three patients had subsequent surgery 9 to 11 months after the procedure. Subsequent surgeries included a dorsal capsulodesis, a four-corner fusion, and a wrist arthrodesis. Of the 8 remaining patients there were 2 excellent, 4 good, 1 fair, and 1 poor result based on the Mayo wrist score. In these patients the mean range of motion was 65 degrees of extension to 59 degrees of flexion and the mean grip strength was 82% of the uninjured contralateral extremity. Although persistent radiographic SL gapping in grip views was noted in all 8 patients none progressed to static instability or dorsal intercalated segment instability. CONCLUSIONS: The results of this technique are suboptimal; however, it may be an option for patients unwilling to have more than an arthroscopic procedure or those requiring maintenance of wrist motion, provided they understand the risks and benefits of this approach. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic, Level IV.

Adult↗
PubMed2006

Outcomes of dorsal capsulodesis and tenodesis for treatment of scapholunate instability.

PURPOSE: The ideal treatment for scapholunate (SL) instability has not yet been established. This study examined the results of 2 procedures for the primary treatment for chronic SL dissociation of dorsal capsulodesis and flexor carpi radialis tenodesis. METHODS: A retrospective analysis was conducted that examined dorsal capsulodesis and tenodesis procedures performed for chronic SL instability between January 1995 and February of 2003. Twenty-nine patients were identified with isolated chronic SL instability. Of the 29 patients, 14 had a dorsal capsulodesis procedure and 15 had a tenodesis procedure. The follow-up period averaged 38 months in the capsulodesis group and 36 months in the tenodesis group. Results were reviewed clinically and radiographically. Groups were compared with a Student t test. RESULTS: Postoperative wrist motion decreased in both groups after surgery. Final wrist range of motion was 64% of the unaffected side in the capsulodesis group and 63% of the unaffected side in the tenodesis group. Postoperative grip strength remained unchanged in both groups; grip strength measured 91% of the unaffected side in the capsulodesis group and 87% of the unaffected side in the tenodesis group. The average Mayo wrist scores were 77 in the capsulodesis group and 74 in the tenodesis group. One frank failure occurred in the tenodesis group resulting in a wrist fusion. There was no statistical difference in the overall wrist motion, grip strength, or wrist scores between the capsulodesis and tenodesis groups. CONCLUSIONS: Dorsal capsulodesis and tenodesis provided improvement in symptoms for patients with chronic SL instability. Both procedures appear to provide similar results in the treatment of this difficult problem.

Adult↗
PubMed2007

Severity of scapholunate instability is related to joint anatomy and congruency.

PURPOSE: To determine whether the bony architecture of the distal radius and proximal scaphoid have a role in stabilizing the scaphoid, and to determine whether a relationship between the bony geometry measurements and the amount of wrist constraint could be determined. METHODS: Eight cadaver wrists were tested in a wrist joint motion simulator. The level of scapholunate instability after sectioning the scapholunate interosseous, radioscaphocapitate, and the scaphotrapezium ligaments was determined and related to radiographic measurements of volar tilt, lateral tilt (ulnar tilt of the radioscaphoid fossa), the depth of the radioscaphoid fossa, and 6 radii of curvature measurements of the proximal scaphoid and distal radius. The force to dorsally dislocate the scaphoid out of the radioscaphoid fossa was computed. RESULTS: The radioscaphoid fossa and scaphoid curvatures were larger in those wrists that did not show gross instability after ligamentous sectioning in the wrist simulator. Similarly, those wrists with a deeper radioscaphoid fossa and greater volar tilt were also more stable. The force required to dislocate these wrists was greater than in those wrists that showed gross carpal instability. CONCLUSIONS: This study suggests that the bony anatomy of the radius and scaphoid have a role in stabilizing the carpus after ligament injury. The effect of ligament sectioning on producing carpal instability may be moderated by the bone geometry of the radiocarpal joint. This may explain why some people may have a tear of the scapholunate interosseous ligament but not present with clinical symptoms.

Biomechanical Phenomena↗
PubMed2005

Results of tri-ligament tenodesis: a modified Brunelli procedure in the management of scapholunate instability.

One hundred and sixty-two patients with a diagnosis of scapholunate instability underwent a modified Brunelli procedure over a 7-year period. One hundred and seventeen were assessed with the help of a questionnaire and, of these, 55 patients attended for clinical evaluation. The mean follow-up was 4 (1-8) years. There were 72 patients with dynamic scapholunate instability and 45 patients with static instability. The average age was 38 years. There were 50 males and 67 females. A total of 77 (62%) patients had no to mild pain with a mean visual analogue score of 3.67 (SD=2.5). The loss in the arc of flexion-extension was due to a reduced range of flexion (mean loss 31%), while 80% of extension was maintained, compared with the contralateral side. The grip strength on the operated side was reduced by 20% of the non-operated side. There was no statistically significant difference (P>0.05) in the range of movement or the grip strength between the static and dynamic group and patients with or without legal claims. Ninety (79%) patients were satisfied with the result of the surgery (good to excellent) and 88% of the patients felt that they would have the same surgery again. We feel that these results compare favourably with the early results published from this unit and recommend this procedure for dynamic and static scapholunate instability.

Adult↗
PubMedDate not supplied

Results and factors affecting outcome of revision surgery for shoulder instability.

We conducted a clinical study identifying the causes of failure and the variables affecting outcome in 28 patients with failed open or arthroscopic anterior shoulder reconstruction for anterior glenohumeral instability. All patients underwent an open revision stabilization procedure. Surgical outcomes at a minimum 24 months' follow-up were available in 25 patients. The most common findings at revision surgery were capsular redundancy and Bankart lesions. Satisfactory results were found in 21 patients (84%) after repeat instability surgery. Factors contributing to negative outcome were glenohumeral arthritis, age greater than 30 years, 2 or more previous instability procedures, a bony Bankart lesion, the diagnosis of multidirectional instability, and surgery involving the nondominant arm (P < .05). Revision shoulder stabilization can be successful when the correct diagnosis is made and appropriate surgery performed. However, the outcome is less predictable in patients with multiple previous surgeries.

Adolescent↗
PubMedDate not supplied

The drop sign, a radiographic warning sign of elbow instability.

Persistent instability or redislocation is uncommon but of significant concern in treating elbow dislocations. Finding an objective, static radiographic sign that might correlate with the presence of instability was the purpose of this study. Pre- and post-reduction radiographs of 10 consecutive simple and complete adult elbow dislocations were reviewed and compared with radiographs of 20 consecutive adult elbows without any trauma history. A statistically significant measured increase in static ulnohumeral distance was noted on the routine unstressed post-reduction lateral radiographs of patients sustaining dislocation. We have termed this increased distance the drop sign. It differs from the radiographic ulnohumeral separation noted during O'Driscoll's test for posterolateral rotary instability, which is present only with axial compression. The drop sign becomes concerning only if persistent after the first reduction radiograph and may be a warning sign of the presence of instability.

Elbow Joint↗
PubMedDate not supplied

Stability and instability of the glenohumeral joint: the role of shoulder muscles.

Shoulder muscles contribute to both mobility and stability of the glenohumeral joint. To improve treatments for shoulder instability, we focused on the contribution of the shoulder muscles to glenohumeral joint stability in clinically relevant positions. Both computational and experimental models were used. A computational model of the glenohumeral joint quantified stability provided by active muscle forces in both mid-range and end-range glenohumeral joint positions. Compared with mid-range positions, the resultant joint force at end-range positions was more anteriorly directed, indicating that its contribution to glenohumeral joint stability was diminished. In end-range positions, simulated increases in rotator cuff muscle forces tended to improve stability whereas increases in deltoid or pectoralis major muscle forces tended to further decrease stability. To validate these results, a cadaveric model, simulating relevant shoulder muscles, was used to quantify glenohumeral joint stability. When infraspinatus muscle activity was decreased, compressive forces decreased. When pectoralis major muscle activity was increased, anteriorly directed forces increased. If anteriorly directed forces increase or compressive forces decrease, stability of the glenohumeral joint decreases. This cadaveric model was then used to evaluate the effect of placing the joint in the apprehension position of abduction, external rotation, and horizontal abduction. Consistent with the results of our computational model, apprehension positioning increased anteriorly directed forces. Knowledge gained from these models was then used to develop a cadaveric model of glenohumeral joint dislocation. Dislocation resulted from the mechanism of forcible apprehension positioning when the appropriate shoulder muscles were simulated and a passive pectoralis major muscle was included. Capsulolabral lesions resulted that were similar to those observed in vivo. Shoulder muscle forces are usually powerful stabilizers of the glenohumeral joint, especially in mid-range positions when the passive stabilizers are lax. However, muscle forces can contribute to instability as well. Certain muscle forces decrease glenohumeral joint stability in end-range positions. We found this to be the case with both active and passive pectoralis major forces. Improved understanding of the contribution of muscle forces not only toward stability but also toward instability will improve rehabilitation protocols for the shoulder and prove useful in the treatment of joint instability throughout the body.

Biomechanical Phenomena↗