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PubMed2000

Selective capsular shift technique for anterior and anterior-inferior glenohumeral instability.

Anterior and anterior-inferior glenohumeral instability is often successfully treated with nonoperative measures, especially in atraumatic instability. In the case of traumatic instability, especially when the labrum is detached from the anteroinferior glenoid rim, surgery is often necessary to stabilize the shoulder and restore function. An anatomic repair that addresses any capsular or labral defect is essential for a successful outcome, and the selective capsular shift technique offers the flexibility necessary to correct these deformities. Several equally important steps must be followed when treating anterior and anterior-inferior glenohumeral instability. These include the correct diagnosis and indications for surgery; a technically successful surgical procedure; and diligent, physician-directed, closely monitored rehabilitation.

Humans↗
PubMed1984

Midcarpal instability caused by malunited fractures of the distal radius.

Thirteen patients with malunited fractures of the distal radius developed symptoms of pain and instability of the midcarpal joint. In six cases, a recurrent voluntary midcarpal subluxation was also present during ulnar deviation. These symptoms were first noticed several weeks, and at times several months, after all immobilization for the treatment of the original fracture had been discontinued. We believe that the loss of the normal palmar tilt of the distal articular surface of the radius prepositions the carpus in a dorsal collapse alignment, which enables this instability to develop. Although the instability is localized to the midcarpus , it is treated best, in our opinion, by a corrective osteotomy of the distal radius. In nine patients, osteotomies resulted in relief of preoperative symptoms and correction of midcarpal instability. In one patient, osteotomy of the radius was deemed unnecessary because the loss of palmar tilt of the radius was minimal. Instead the midcarpal ( triquetrohamate ) joint was stabilized by ligament reconstruction. Only transient correction was obtained, with later recurrence of the voluntary midcarpal subluxation.

Adolescent↗
PubMed1987

Load transfer characteristics of the wrist. Part II. Perilunate instability.

An experimental model with a static positioning frame, pressure-sensitive film (Fuji), and a microcomputer-based video digitizing system, previously developed by the two senior authors, was used in this study to examine the effects of increasing perilunate instability on the load transfer characteristics of the wrist. These effects included a significant dorsal ulnar shift of the scaphoid centroid with increasing perilunate instability together with a less dramatic palmar ulnar shift of the lunate centroid. Overall, the scaphoid contact area was found to decrease as the stage of perilunate instability increased, even in ulnar deviation and/or extension, which in the normal wrist was found to be the positions that had the greatest scaphoid contact area. Average pressures in the high pressure zones were found to significantly increase in wrists with a stage III instability compared with normal wrists. An increase in the intercentroid (scaphoid/lunate) distance was most evident with the wrist in 20 degrees extension, neutral radioulnar deviation, and 90 degrees supination.

Biomechanical Phenomena↗
PubMed1997

Ligamentous instabilities of the wrist.

Carpal ligament instabilities are conditions in which the individual carpal bones have become unstable due to abnormal ligament support. Early diagnosis of ligamentous wrist instabilities is important because late diagnosis or failed diagnosis may lead to severe complications such as osteoarthritis. This article reviews the most common ligamentous instability patterns of the wrist and focuses on how to perform and obtain radiograms which will allow reliable diagnosis of wrist instabilities.

Algorithms↗
PubMed1994

Capsular elasticity and joint volume in recurrent anterior shoulder instability.

It is commonly claimed that unstable shoulders have an altered capsular elasticity and increased joint volume. To find out if there is a correlation between anterior instability and increased joint volume, 20 patients were examined while undergoing arthroscopic surgery of the shoulder. There were four anterior subluxators, 11 anterior dislocators, and five bilateral dislocators, and in all patients the contralateral shoulder was also examined. During continuous saline infusion, a pressure/volume curve was recorded within the range of 0-180 mm Hg. Joint volume was correlated with body surface area. Among the 15 patients with unilateral instability, there was no correlation between joint volume and body surface area. There were no differences in joint volume or capsular elasticity between the healthy and the unstable shoulder in any patient. It is concluded that capsular elasticity and joint volume contribute little to anterior shoulder instability and that instability probably depends more on damage to other stabilising structures in the joint.

Adolescent↗
PubMed1997

The arthroscopic treatment of multidirectional shoulder instability: two-year results of a multiple suture technique.

Nineteen consecutive shoulders in 19 patients were treated for multidirectional shoulder instability with an arthroscopic capsular shift. Indications for the procedure included complaints of pain, instability, or both that was unresponsive to a prescribed exercise program that stressed rotator cuff and scapular stabilizer strengthening. All patients had evidence of increased joint laxity on physical examination; 17 had a 2+ or greater sulcus test and 2 had 3+ laxity both anteriorly and posteriorly. Fourteen of the 19 patients were injured during athletic activity. All surgeries were performed in an outpatient setting. All the patients were evaluated at an average of 34 months postoperatively with a minimum follow-up of 25 months. Based on the outcome scale described by Tibone and Bradley, the average postoperative score was 91 out of a possible 100 with 13 excellent, 5 good, and 1 fair result. All but 1 of the athletes returned to their previous level of performance but none were elite throwers. One patient had recurrent anterior subluxations treated with a repeat arthroscopic capsular shift and was rated as good. The patient rated as fair had no improvement in her pain after surgery. One patient complained of a painful supraclavicular suture that resolved spontaneously. There were no neurovascular complications or infections. Visualization of intra-articular pathology was enhanced with the arthroscope and aided in the diagnosis of multidirectional instability. The described technique proved safe and effective in treating multidirectional instability and enabling athletes to return to their previous level of function.

Adult↗
PubMed1997

The arthroscopic treatment of posterior shoulder instability: two-year results of a multiple suture technique.

This study was undertaken to review the results of an arthroscopic posterior capsular shift procedure. Twenty consecutive shoulders in 19 patients were treated with an arthroscopic posterior capsular shift for symptomatic posterior shoulder instability. Patients underwent the procedure if they exhibited a posterior Bankart lesion or had complaints of posterior instability and evidence of increased posterior joint laxity on physical examination and examination under anesthesia. Twelve of the 20 patients were injured during athletic activity. All surgeries were performed in an outpatient setting. Twelve of the 20 patients had posterior Bankart lesions and 10 had anterior Hill-Sachs lesions. The procedure entails releasing the posterior labroligamentous structures from the posterior glenoid and freshening the glenoid neck with a bur. A suture punch is used to place multiple absorbable monofilament stitches in the ligament complex. The stitches are brought through a supraclavicular portal and tied over the clavicle or scapular spine. All 20 shoulders were evaluated at an average of 31 months postoperatively with a minimum follow-up of 24 months. Based on the outcome scale described by Tibone and Bradley, the average postoperative score was 83 out of a possible 100, with 15 excellent, 2 good, 1 fair, and 3 poor results. There were two recurrent dislocations and three subluxations for an overall recurrence rate of 25%. All the recurrences occurred in patients with posterior Bankart lesions and four of the five had a voluntary component to their instability. There were no neurovascular complications or infections. Arthroscopic evaluation facilitated the diagnosis of posterior instability with the visualization of intra-articular pathology that is difficult to identify during open procedures. Although the majority of patients were able to return to vigorous activities, a recurrence rate of 25% is disturbing and consistent with recurrence rates for open procedures.

Adult↗
PubMed1993

[Triquetro-lunar instability. The role of the radio-styloidian index].

Based on a series of 13 isolated triquetro-lunar instabilities, the authors underline the excess of the radio styloidian index measured radiologically. They found a significant difference (p < 0.001) when comparing this series with a group of 100 normal wrists. A similar comparative study of 13 triquetro-lunar instabilities secondary to perilunar dislocations and of a series of 16 hyperlax wrists did not reveal any significant difference. The same applies to a similar parallel study of the ulnar variance index measurements when comparing the various groups with the control group. After reviewing the mechanism of lesions, and disorders of the wrist's axial forces, caused by changes in the ulnar lengths, ulnar styloid overshooting is designated as a risk factor for isolated triquetro-lunar instabilities. Finally, the authors insist on the necessity of proper reduction of radial low end fractures and detachments, and on the shortening of the long ulna, as a "complementary" procedure when treating isolated triquetro-lunar instabilities.

Adolescent↗
PubMedDate not supplied

A 4-portal arthroscopic stabilization in posterior shoulder instability.

The purpose of this study was to present an arthroscopic stabilization technique with 4 portals for posterior instability used in 11 patients (13 shoulders). There were 7 male and 4 female patients. All patients had an arthroscopic labral suture with anchors and capsular plication with 4 portals. The follow-up period averaged 34 months. No complication or recurrence of instability was noted. A moderate loss of range of motion was noted in 4 shoulders and moderate pain in 2 shoulders. All patients were satisfied. According to the literature, the rate of recurrence of instability is currently lower than 12% when a labral suture and capsular plication are performed. Our results for pain and range of motion are similar to those described in recent publications. However, we think that the 4-portal technique allows a facilitated access to the posteroinferior part of the glenoid and reduces the rate of postoperative instability.

Adolescent↗
PubMedDate not supplied

Recurrent instability of the shoulder after age 40.

Twelve patients who had recurrent instability of the shoulder with onset after age 40 were reviewed. Eleven had anterior instability, and one had a posterior dislocation. The average age of the patients was 62.7 years. Symptoms began soon after initial injury. All patients with anterior instability had ruptured the subscapularis and anterior capsule from the lesser tuberosity, whereas the posterior dislocator had torn the infraspinatus and upper teres minor with the posterior capsule from the greater tuberosity. No patient had a Bankart lesion. Stability was restored in all cases by reattaching the ruptured tendons and capsule to the tuberosities. Follow-up was from 2 to 13 years. One patient required a reoperation. All patients now have a stable shoulder. Recurrent instability of the shoulder after age 40 can be caused by rotator cuff and capsular rupture from the tuberosities without additional significant injury to the ligamentolabral complex. In such cases, repairing the torn structures is sufficient to restore stability.

Adult↗
PubMedDate not supplied

Comparative electromyographic analysis of shoulder muscles during planar motions: anterior glenohumeral instability versus normal.

This study compared the electromyographic activity of rotator cuff and scapular muscles between subjects with anterior instability and subjects with normal shoulders. Thirty-eight patients were studied; 23 had anterior instability that was subsequently surgically confirmed, and 15 had normal shoulders. Fine wire electrodes were inserted into the subscapularis (upper and lower portions), supraspinatus, infraspinatus, rhomboid, serratus anterior, and trapezius (upper and lower portions) muscles. Abduction, scapular plane abduction (scaption), and forward flexion were performed over the range of motion and later divided into 30 degrees intervals. In both abduction and scaption, the supraspinatus demonstrated significantly less electromyographic activity from 30 degrees to 60 degrees in shoulders with anterior instability compared with normal shoulders (p < 0.05). During all three motions, shoulders with anterior instability demonstrated significantly less electromyographic activity in the serratus anterior when compared with normal shoulders (p < 0.05). This occurred at 30 degrees to 120 degrees of abduction and at 0 degree to 120 degrees of scaption and forward flexion. None of the other muscles demonstrated significant differences. These differences during planar motions were similar to those demonstrated during challenging overhead sport motions. Early rehabilitation efforts should focus both on the rotator cuff and scapular muscles to establish smooth, coordinated shoulder motion.

Adolescent↗
PubMedDate not supplied

Open and arthroscopic techniques for the treatment of traumatic anterior shoulder instability in Australian rules football players.

Australian Rules football (ARF) is a potentially violent, overhead, body-contact sport. We reviewed 56 shoulders in patients who sustained their initial traumatic anterior subluxation or dislocation during ARF and who underwent reconstructive surgery for traumatic anterior instability, whether by arthroscopic or by open techniques. Patients were followed up for a mean of 29.4 months after operation, and clinical evaluation was performed with the Rowe grading system. Three types of surgical procedures were performed: arthroscopic suture repair, arthroscopic Bankart repair with an absorbable polyglyconate tack, and open capsular shift with repair of the Bankart lesion. Shoulders treated with arthroscopic suture repair had a 70% rate of recurrent subluxation or dislocation on return to ARF Dislocations treated arthroscopically with the biodegradable tack had a 38% rate of recurrence of instability; three fourths of the recurrences were after minimal to moderate trauma. Shoulders treated with an open capsular shift and Bankart procedure had a 30% rate of recurrent instability, with half of the recurrences caused by violent trauma. In the open group there were no failures in patients who did not return to ARF. We suggest that arthroscopic repair in shoulders with anterior instability and recurrent dislocation does not adequately address the plastic deformation of the anterior capsule that may occur after repeated episodes of dislocation. We advocate open shoulder procedures in ARF athletes to address all areas of the capsulolabral pathologic condition and to provide the most secure repair possible with minimal chance of recurrence.

Adolescent↗
PubMedDate not supplied

Translation of the glenohumeral joint in patients with anterior instability: awake examination versus examination with the patient under anesthesia.

Fifty patients with a clinical diagnosis of traumatic anterior shoulder instability underwent bilateral shoulder translation testing while both awake and under anesthesia. Each patient was examined by 2 surgeons following guidelines developed by the American Shoulder and Elbow Surgeons. A single translation grade was established for anterior, posterior, and inferior directions. A comparison of means was performed with a paired t test. The mean anterior translation grade was significantly higher on the affected side when compared with that of the unaffected side both during awake examination and during examination with the patient under anesthesia (EUA). Ipsilateral comparison revealed significantly greater translation for both affected and unaffected shoulders in anterior, posterior, and inferior directions during EUA than during awake examination. Side-to-side comparison of posterior and inferior translation was similar for both awake examination and EUA. Clinical translation testing was helpful in the diagnosis of anterior shoulder instability. Side-to-side differences were subtle while awake and more apparent during EUA. The usefulness of awake translation testing for traumatic anterior instability was not clearly demonstrated; however, EUA provides helpful information to confirm the direction and degree of instability.

Adult↗
PubMedDate not supplied

Functional instability of the ankle and the role of neuromuscular control: a comprehensive review.

A review of current knowledge of the clinical syndrome of functional ankle instability is presented. Recent evidence has demonstrated that the majority of patients with functional instability of the ankle do not have mechanical hypermobility of the ankle joint. Functional instability of the ankle results from a loss of neuromuscular control. Components of neuromuscular control include proprioception, muscle strength, muscle reaction time, and postural control. Proprioceptive deficits lead to a delay in peroneal reaction time, which appears to be a peripheral reflex. Proprioception and eversion muscle strength improve with the use of passive supportive devices. Balance and postural control of the ankle appear to be diminished after a lateral ankle sprain and can be restored through training that is mediated through central nervous mechanisms. Methods of detecting deficits in neuromuscular control are presented along with rehabilitation techniques to treat functional instability of the ankle.

Ankle Injuries↗
PubMed2004

Centrosome amplification and the origin of chromosomal instability in breast cancer.

The development and progression of aggressive breast cancer is characterized by genomic instability leading to multiple genetic defects, phenotypic diversity, chemoresistance, and poor outcome. Centrosome abnormalities have been implicated in the origin of chromosomal instability through the development of multipolar mitotic spindles. Breast tumor centrosomes display characteristic structural abnormalities, termed centrosome amplification , including: increase in centrosome number and volume, accumulation of excess pericentriolar material, supernumerary centrioles, and inappropriate phosphorylation of centrosome proteins. In addition, breast tumor centrosomes also show functional abnormalities characterized by inappropriate centrosome duplication during the cell cycle and nucleation of unusually large microtubule arrays. These observations have important implications for understanding the mechanisms underlying genomic instability and loss of cell polarity in cancer. This review focuses on the coordination of the centrosome, DNA, and cell cycles in normal cells and their deregulation resulting in centrosome amplification and chromosomal instability in the development and progression of breast cancer.

Aneuploidy↗
PubMed2003

Role of genetic background in induced instability.

Genomic instability is effectively induced by ionizing radiation. Recently, evidence has accumulated supporting a relationship between genetic background and the radiation-induced genomic instability phenotype. This is possibly due to alterations in proteins responsible for maintenance of genomic integrity or altered oxidative metabolism. Studies in human cell lines, human primary cells, and mouse models have been performed predominantly using high linear energy transfer (LET) radiation, or high doses of low LET radiation. The interplay between genetics, radiation response, and genomic instability has not been fully determined at low doses of low LET radiation. However, recent studies using low doses of low LET radiation suggest that the relationship between genetic background and radiation-induced genomic instability may be more complicated than these same relationships at high LET or high doses of low LET radiation. The complexity of this relationship at low doses of low LET radiation suggests that more of the population may be at risk than previously recognized and may have implications for radiation risk assessment.

Animals↗
PubMed2004

Carcinogen-induced colon tumors in mice are chromosomally stable and are characterized by low-level microsatellite instability.

The azoxymethane (AOM)-induced mouse colon tumor model recapitulates many of the histopathological features associated with the multistage progression of human sporadic colorectal cancers (CRCs). To better define the genetic events associated with tumorigenesis in this murine model, we analysed tumors from A/J mice for chromosomal (CIN) and microsatellite (MSI) instabilities, two fundamental pathways of genomic instability that play a critical role in the pathogenesis of human CRCs. Male A/J mice, 6-week old, were injected with either AOM (n=5) (10 mg/kg b.w., i.p.) or vehicle (n=5) (0.9% NaCl solution) once a week for 6 weeks. At 32 weeks after the last dose, comparative genomic hybridization (CGH) was performed on 16 tumors harvested from five animals. Although 25% of the tumors displayed either a gain of chromosome 2 or loss of Y, the majority (75%) showed no genomic imbalances. Further analysis of chromosomal aberrations, using CGH and spectral karyotyping (SKY) was performed in our recently established A/J colon tumor-derived cell line, AJ02-NM0. Results showed a pseudotetraploid karyotype with loss of only the Y chromosome in these cultured cells, thereby providing additional evidence for the minimal role of CIN in the primary AOM-induced tumors. Interestingly, the majority (81%) of A/J tumors displayed low-level microsatellite instability (MSI-L) when analysed using mono- and dinucleotide repeat markers, and showed a significant expansion to high-level instability (MSI-H) in the AJ02-NM0 cells. This finding in cultured cells additionally provides evidence that a mild mutator pathway may contribute to the development of behaviorally benign carcinomas in situ in A/J mice. To better understand the tumorigenic process in the A/J colons, we screened for mutational alterations in key regions of the K-ras and Apc genes. Results showed a very low frequency (6%) of K-ras activating mutations, together with the absence of Apc truncation mutations in primary tumors and AJ02-NM0 cells. However, these tumors displayed intense nuclear accumulation of beta-catenin protein, indicating activation of the Wnt signaling pathway. Based on our molecular and cytogenetic findings, we propose that carcinogen-induced tumors may develop via mechanisms independent of the 'classical' CIN or MSI pathways.

Aneuploidy↗
PubMed2000

Hill-Sachs type lesion of the femoral head in a case of hip instability.

A Hill-Sachs lesion of the shoulder is an indicator of shoulder instability. Hip instability is also a well-recognized phenomenon. However, no operative or arthroscopic features have previously been reported that support the diagnosis of hip instability. We present a case report of a Hill-Sachs type lesion of the femoral head in a patient with acetabular dysplasia revealed by arthroscopy of the hip. We suggest that finding a Hill-Sachs type lesion of the femoral head may also be regarded as indicative of joint instability, just as it is in the shoulder.

Adult↗