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At least 667 records · Page 37Linked to original sources
PubMed2003

The use of a constrained acetabular component to treat instability after total hip arthroplasty.

BACKGROUND: Recurrent dislocation after total hip arthroplasty is a disabling complication that can be difficult to treat and may not be amenable to nonoperative management. The purpose of the present study was to evaluate the clinical and radiographic outcome associated with the use of a constrained acetabular component as a salvage treatment for instability after hip arthroplasty. METHODS: We retrospectively reviewed the clinical and radiographic outcome of 110 arthroplasties, in 109 patients, that had been performed with use of a single design of constrained acetabular component. In seventy-nine hips the constrained component was implanted for the treatment of recurrent instability, and in thirty-one hips it was implanted because of absent or grossly deficient soft-tissue attachments that were believed to be associated with a high risk for subsequent instability. RESULTS: The constrained acetabular device eliminated or prevented hip instability in all patients except two, who continued to have sensations of subluxation. The mean Harris hip score improved significantly, from 62.7 points preoperatively to 76.4 points at the time of the latest follow-up (p < 0.0001). There were no instances of dislocation or disassembly of the hip components. Radiographic analysis revealed radiolucent lines around the cup in fifteen hips (14%). There was a total of nine revisions: six for deep infection, two for acetabular component loosening, and one for a periprosthetic fracture of the femur. CONCLUSIONS: A constrained acetabular component reliably restores and maintains hip stability in patients with recalcitrant recurrent instability and can dependably prevent dislocation in those who are at high risk because of absent or deficient soft tissues about the hip. However, because of the early appearance of radiolucent lines around some components and concerns about long-term fixation, the use of these devices should be reserved for situations in which other methods are inadequate or have already failed.

Adult↗
PubMed2003

Genomic instability and cancer.

Tumorigenesis can be viewed as an imbalance between the mechanisms of cell-cycle control and mutation rates within the genes. Genomic instability is broadly classified into microsatellite instability (MIN) associated with mutator phenotype, and chromosome instability (CIN) recognized by gross chromosomal abnormalities. Three intracellular mechanisms are involved in DNA damage repair that leads to mutator phenotype. They include the nucleotide excision repair (NER), base excision repair (BER) and mismatch repair (MMR). The CIN pathway is typically associated with the accumulation of mutations in tumor suppressor genes and oncogenes. Defects in DNA MMR and CIN pathways are responsible for a variety of hereditary cancer predisposition syndromes including hereditary non-polyposis colorectal carcinoma (HNPCC), Bloom syndrome, ataxia-telangiectasia, and Fanconi anaemia. While there are many genetic contributors to CIN and MIN, there are also epigenetic factors that have emerged to be equally damaging to cell-cycle control. Hypermethylation of tumor suppressor and DNA MMR gene promoter regions, is an epigenetic mechanism of gene silencing that contributes to tumorigenesis. Telomere shortening has been shown to increase genetic instability and tumor formation in mice, underscoring the importance of telomere length and telomerase activity in maintaining genomic integrity. Mouse models have provided important insights for discovering critical pathways in the progression to cancer, as well as to elucidate cross talk among different pathways. This review examines various molecular mechanisms of genomic instability and their relevance to cancer.

Animals↗
PubMed1983

Fracture of the radius with instability of the wrist.

Review of 190 consecutive fractures of the distal radius revealed 14 instances of ligamentous carpal instability (7.4%). Instability was more likely to occur in older patients but was not related to the degree of fracture displacement. There was an association between instability and radial styloid fracture, and in five of nine Colles fractures a separate radial styloid fragment was present, suggesting a component of avulsive force. The relatively common coexistence of fracture and instability is not generally appreciated, and the findings of instability often are overlooked.

Humans↗
PubMed2003

MR arthrography of the posterior labrocapsular complex: relationship with glenohumeral joint alignment and clinical posterior instability.

OBJECTIVE: The purpose of our study was to investigate the relationship between tears of the posterior labrocapsular complex and glenohumeral alignment on MR arthrography and the presence and extent of posterior labrocapsular tears in patients with posterior instability. MATERIALS AND METHODS: Posterior labrocapsular tears identified on 24 MR arthrograms and surgically confirmed were evaluated for length of tear and labrocapsular avulsion. These examinations and a comparison cohort of 70 normal MR arthrograms with normal findings were also evaluated for humeral head position relative to the glenoid fossa. Medical records were reviewed for clinical diagnosis of posterior instability and history of shoulder trauma. RESULTS: The position of the humeral head relative to the glenoid was significantly more posterior in patients with posterior labral tear than in patients with a normal posterior labrum (4.9 mm versus 0.7 mm; p < 0.0001). The mean length (+/- SD) of posterior labral tear was 15.9 +/- 1.7 mm, and a direct correlation was found between tear length and posterior humeral translation (r = -0.65; p = 0.002). Posterior labral tears were significantly longer (18.6 vs 13.1 mm; p = 0.04), and posterior humeral translation was greater (6.4 vs 3.4 mm; p = 0.006) in patients with labrocapsular avulsion than in those without avulsion. Twelve (50%) of the patients with posterior labrocapsular tear had posterior instability, and 10 (83%) had a history of macrotrauma. On MR arthrography, the mean posterior humeral translation was greater (6.2 mm +/- 0.08; p = 0.019), posterior labral tears were longer (19.4 mm +/- 1.7; p = 0.0008), and labrocapsular avulsion was more common (83%; p = 0.0001) in patients with posterior instability than in patients who had a posterior labral tear but a clinically stable shoulder. CONCLUSION: Clinical posterior instability is associated with excessive posterior humeral translation, long posterior labral tears, and posterior labrocapsular avulsion.

Adolescent↗
PubMed1996

Proprioception during manual aiming in individuals with shoulder instability and controls.

Recurrent glenohumeral joint instability is a common orthopaedic problem. One possible cause of this repeated instability is a lack of neuromuscular control and kinaesthetic sense of the glenohumeral joint. The purpose of this study was to determine whether there is a deficit in joint proprioception in subjects with recurrent anterior glenohumeral instability as compared with individuals with no previous shoulder pathology. Subjects were asked to generate pointing movements with their uninjured limb and to match this limb position with the injured limb. Movements of the pointing limb were measured with an optoelectric three-dimensional movement analysis system. These movements were performed in three conditions: 1) with full vision, 2) without vision, and 3) without vision with vibration to the posterior deltoid muscle. For the temporal and spatial measures, there were no significant differences between the control and shoulder instability groups. However, the kinematic data describing arm trajectory formation showed a performance decrement in the no vision with vibration condition for the subjects in the shoulder instability group, suggesting that they suffer from a proprioceptive deficit.

Adult↗
PubMed2005

Emerging roles of centrosomal amplification and genomic instability in cancer.

The carcinogenic process is multistep in terms of its etiology and multifactor in terms of its evolution. In this context, the temporal accumulation of multiple genetic changes during multistage carcinogenesis that can be mediated at least in part by genomic instability may represent crucial components of tumor cell evolution. Evidence is accumulating indicating a close link between genomic instability and cancer initiation and progression. Neoplastic cells typically possess numerous genomic lesions, which may include sequence alterations (point mutations, small deletions, and insertions) and/or gross structural abnormalities in one or more chromosomes (large-scale deletions, rearrangements, gene amplifications). Furthermore karyotypic alterations, including whole chromosome loss or gain, ploidy changes (aneuploidy and polyploidy) and a variety of chromosome aberrations are common in tumor cells. Genomic instability also involves mitotic defects associated with centrosome abnormalities. However, the question of whether abnormal centrosomes cause genomic instability or develop secondary to other changes has not been conclusively resolved. In this review, the recent studies investigating genomic instability and aneuploidy in human cancer, centrosome amplification and the role of centrosomal duplication in chromosomal mis-segregetion, and genes implicated in regulating chromosome segregation, centrosomal amplification and progression in cancer cells are discussed.

Aneuploidy↗
PubMed1984

Instability of total hip prostheses at rotational stress. A roentgen stereophotogrammetric study.

Roentgen stereophotogrammetric analysis (RSA) has been carried out on 24 total hip prostheses (24 patients), which were all painful at weightbearing. The examinations were made with the hip at distraction, compression, external and internal rotation. One acetabular component showed instability only at distraction-compression and one showed instability only at rotation. Four femoral components showed instability at distraction-compression and at rotation, six only at rotation, but none showed instability only at distraction-compression. Thus rotational provocation demonstrated instability in all unstable femoral components; rotational stress must be of importance in mechanical loosening of the femoral component.

Acetabulum↗
PubMed1991

Anterolateral instability in the anterior cruciate ligament deficient knee. A cadaver study.

Knee instability was evaluated in 13 normal osteoligamentous knee preparations after transection of the anterior cruciate ligament. Abduction-adduction rotation, coupled tibial translatory movement, and coupled tibial axial rotation were recorded continuously and simultaneously during flexion or extension while applying a well defined valgus directed moment and during extension while applying an anterior tibial force. As a result of the valgus-directed moment, an increase was found in abduction rotation, in coupled anterior tibial translation, and in coupled internal tibial axial rotation. Coupled rotatory and translatory instabilities were larger, and maximum instability was observed at a smaller knee angle during the extension movement than during the flexion movement. The pattern of the instability, excited as a result of the valgus moment, was different from the instability excited as a result of an anterior tibial force.

Aged↗
PubMed2004

Cervical magnetic resonance imaging abnormalities not predictive of cervical spine instability in traumatically injured patients. Invited submission from the Joint Section Meeting on Disorders of the Spine and Peripheral Nerves, March 2004.

OBJECT: Identifying instability of the cervical spine can be difficult in traumatically injured patients. The goal of this study was to determine whether cervical abnormalities demonstrated on magnetic resonance (MR) imaging are predictive of spinal instability. METHODS: Data in all patients admitted through the Level I trauma service at the authors' institution who had undergone cervical MR imaging were retrospectively reviewed. The reasons for MR imaging screening were neurological deficit, fracture, neck pain, and indeterminate clinical examination (for example, coma). Abnormal soft-tissue (prevertebral or paraspinal) findings on MR imaging were correlated with those revealed on computerized tomography (CT) scanning and plain and dynamic radiography to determine the presence/absence of cervical instability. Of 6328 patients admitted through the trauma service, 314 underwent MR imaging of the cervical spine. Of 166 patients in whom CT scanning or radiography demonstrated normal findings, 70 had undergone MR imaging that revealed abnormal findings. Of these 70 patients, 23 underwent dynamic imaging, the findings of which were normal. In each case of cervical instability (65 patients) CT, radiographic, and MR imaging studies demonstrated abnormalities. Furthermore, there were 143 patients with abnormal CT or radiographic study findings, in 13 of whom MR imaging revealed normal findings. Six of the latter underwent dynamic testing, which demonstrated normal results. CONCLUSIONS: Magnetic resonance imaging is sensitive to soft-tissue injuries of the cervical spine. When CT scanning and radiography detect no fractures or signs of instability, MR imaging does not help in determining cervical stability and may lead to unnecessary testing when not otherwise indicated.

Adult↗
PubMed1999

[Treatment of chronic ankle instability with the Chrisman-Snook's technique].

PURPOSE OF THE STUDY: We report our experience on lateral ankle instability treated by the Chrisman Snook procedure. We studied the objective and subjective results as well as the effect on peroneus brevis tendon function. MATERIAL AND METHODS: Among 110 patients treated for chronic lateral ankle instability between 1991 and 1997, 32 cases were treated with this technique. The average age was 25 years (16-37) and the average time to surgery from the initial trauma was 30 months. This was a retrospective study using the Karlson Peterson form while the laxity was measured with Telos device (120 N). Cybex testing was performed on 10 patients. Twenty-seven patients participated in sport. RESULTS: The follow-up ranged from 6 to 65 months (average 25 months). The average Karlson's score was 82.6 with 78 per cent excellent and good results. Lateral ligament laxity was reduced from 17 mm to 4 mm on Telos measurements and no osteoarthritis was noticed radiographically. The joint mobility consistently returned to the preoperative level. Twenty four patients returned to sport although half of the patients had some pain during sport activities or with fast walking. DISCUSSION: Males and patients participating in sporting activities had the best results and none of the patients had recurrent instability despite new sport injuries. The persistence of some pain may be associated with the long period of instability prior to reconstruction in this group of patients. CONCLUSION: The Chrisman Snook lateral ligament reconstruction is a technically easy and solid technique and we recommend it in patients with significant chronic lateral ligament instability.

Adolescent↗
PubMed2000

[Shoulder instability: diagnostic imaging].

Shoulder instability is often diagnosed among athletes; two clinical forms are distinguished: anatomical instability, with recurrent luxation of the shoulder, and functional instability, with pain, articular "click" and sensation of instability. Lesions of periarticular soft tissues (capsula, fibrocartilaginous labrum, gleno-humeral ligaments and rotator cuff) are common in both forms, while lesions of bone structures (humeral head and glenoid of scapula) are typical of shoulder with previous dislocation. Purpose of our retrospective study was to verify the value of magnetic resonance (MRI) and computed arthrography (arthro-CT) in diagnosing these lesions in 57 patients suffering from shoulder instability. On the basis of our results and experience we think that in a preoperative evaluation of an unstable shoulder, arthro-CT and arthro-MRI are more accurate because the intra-articular injection of a contrast medium better identifies lesions of capsula, gleno-humeral ligaments and fibrocartilaginous labrum. In other circumstances, such as the study of the shoulder for legal purposes, MRI is preferable because it offers an accurate and global evaluation of periarticular structures.

Adolescent↗
PubMed2001

The breech presentation and the vertex presentation following an external version represent risk factors for neonatal hip instability.

UNLABELLED: The aim of this study was to evaluate the frequency and type of hip-joint instability and the frequency of hip dislocation requiring treatment in neonates who had been lying in the breech presentation and were delivered vaginally after an external version or by caesarean section, and to compare them with neonates who were naturally in the vertex presentation. Breech presentations without ongoing labour were subjected to an attempted external version and, in cases where this proved unsuccessful or where labour had started, to deliver by caesarean section. None of the breech presentations was vaginally delivered. The anterior-dynamic ultrasound method was used to assess the hip-joint status of the neonates. Out of 6,571 foetuses, 257 were in breech presentation after 36 wk of pregnancy. Sixty-two were vaginally delivered following an external version to vertex presentation and 195 were delivered by caesarean section, 75 of these following unsuccessful attempts to perform a version. Treatment for congenital hip-joint dislocation was performed on 0.2%. Out of the breech presentations, 1.0% of those delivered by caesarean section were treated, while in those with vaginal delivery following an external version the treatment frequency was 3.2%. No case of late diagnosed hip dislocation was recorded. Significant differences in frequency of hip-joint instability and treatment were found between (i) neonates delivered in breech presentation and those delivered with vertex presentation, (ii) infants delivered in vertex presentation, naturally or after successful version, and (iii) those delivered by caesarean section with or without attempted external version and those delivered with vortex presentation. CONCLUSION: Breech presentation predisposes to increased hip instability. The instability is present prior to delivery and is certainly not a primary result of delivery forces. Both breech and vertex presentations following an external or spontaneous version should be considered as risk factors for neonatal hip instability.

Breech Presentation↗
PubMed2001

Shoulder instability. Diagnosis and management.

BACKGROUND: The shoulder is the most commonly dislocated joint in the body. The most frequent complication of shoulder dislocation is recurrence, occurring most often in young athletes. OBJECTIVE: To summarise the functional anatomy of the shoulder joint, the structures damaged following shoulder dislocation and the methods to evaluate and treat shoulder instability. DISCUSSION: Clinical history is effective for diagnosing obvious shoulder instability. The O'Brien's sign (for superior labral lesions), the sulcus sign (for capsular laxity) and the apprehension sign (for anterior instability) are helpful clinical tests for more subtle instabilities. Labral disruptions and capsular laxity can often be restored by minimally invasive (arthroscopic) methods. Rehabilitation aims to enhance the dynamic muscular and proprioceptive restraints to shoulder instability.

Exercise Therapy↗
PubMed1998

[Perilunate progressive instability of the wrist: a study of wrist dynamics].

OBJECTIVE: To study the changes in dynamics of wrist motor tendons after perilunate instability of the wrist. METHODS: 14 cadaver upper extremities were used. Excursions of the principle wrist and finger motor tendons were measured during wrist flexion-extension and radiolunar deviation was determined. Data were collected in the intact wrist, then in the wrist with stage I, II and III perilunate instability. The average moment arms of the tendons during wrist motion were calculated. RESULTS: The moment arms of the wrist flexors increased and those of the finger flexors decreased after instability. Increase in the moment arms dominated changes of radial side wrist motors, while decrease in the moment arms dominated ulnar wrist motors. Moment arms of the flexor carpi radialis tendon showed a consistent increase during wrist motion. CONCLUSION: The changes in wrist dynamics play an important role in clinical manifestations of perilunate instability. The significance of kinetic information on principle of treatment of the instability is discussed.

Biomechanical Phenomena↗
PubMed2003

Arthroscopic stabilization in posterior or multidirectional instability of the shoulder.

The diagnosis and treatment of posterior or multidirectional instability of the shoulder can be difficult. Normal laxity must be differentiated from pathologic instability. Once clinically diagnosed, there are several likely factors that contribute to pathologic instability. Although many patients with posterior or multidirectional instability of the shoulder respond well to nonsurgical treatment, when surgical intervention is required, the success rate has not been as favourable as that for repairing isolated anterior instability of the shoulder.

Arthroscopy↗
PubMed2003

[Treatment of anterior glenohumeral instability: personal experience with an arthroscopic stabilization technique, its indications and results].

PURPOSE OF THE STUDY: Arthroscopic treatment of anterior post-traumatic instability of the glenohumeral joint is a recent surgical procedure. The aim of this study was to evaluate the outcomes of the method and define criteria on which indications for this treatment are based. MATERIAL: Fifty-six active, young patients less than 30 years of age were distributed into three groups according to the method of treatment. Twenty patients were treated conservatively (group A), 12 patients had open surgery (B) and 23 patients underwent arthroscopic stabilization of the glenohumeral joint (C). The average follow-up periods in groups A, B and C were 26, 38 and 18 months, respectively. The treatment of all patients in groups B and C was preceded by physical therapy lasting at least 3 months. Contraindications to arthroscopic treatment included Hill-Sachs bony defects, instability involving a fracture of the glenoid cavity, conditions after previous surgery, posterior or multidirectional instability and anterior instability due to a full rupture of the rotator cuff. METHODS: Conservative treatment consisted of early closed reduction, 3 to 4 weeks of immobilization and subsequent physical therapy. Open procedures for Bankart lesions were carried out according to either Cave and Rowe or Bristow, with post-operative immobilization for 4 weeks. Arthroscopic stabilization was performed by the Wolf method. After the size of the defect had been identified, the glenoid rim was scratched to bleed, the detached labrum, including the inferior glenohumeral ligament, was mobilized and, after drilling holes in the glenoid rim, the capsulolabral complex was fixed by means of a Mitek GII anchor with a 1-0 PDS fibre. Three anchors were inserted as a rule. In each group, the number of recurrent dislocations was recorded. In the patients undergoing surgery, the loss of passive external rotation in 90 degrees abduction was assessed and the outcome was evaluated according to the Rowe rating system. RESULTS: Recurrent dislocations were experienced by 13 patients (65%) in group A and two patients (8.7%) in group C; no recurrent dislocation occurred in group B patients. The average loss of external rotation in 90 degrees abduction was 11.3 degrees and 6.7 degrees in groups B and C, respectively. The Rowe scores showed an excellent outcome in 80%, good in 8%, satisfactory in 2% and poor outcomes in 10% of the group B patients; in group C 78% had excellent, 7% had good, 8% had satisfactory, and 7% had poor outcomes. DISCUSSION: The number of recurrent dislocations (8.7%) in our patients treated by arthroscopy was in agreement with the literature data (1 to 40%); both figures refer to recurrent dislocations in subjects involved in body-contact sports. In our patients treated by arthroscopy, the average post-operative loss of external rotation in 90 degrees abduction was lower than in the open surgery group. There were no differences in the Rowe scores between the two surgically treated groups. The patients treated conservatively showed a high number of recurrent dislocations (65%), thus confirming reports by other authors on the failure of this method. CONCLUSIONS: The arthroscopic treatment of anterior post-traumatic glenohumeral instability, using the Wolf method, resulted in a reduction of recurrent dislocations, supposing indication criteria were observed. Its outcomes were comparable with the results of conventional open surgery.

Adolescent↗
PubMed2003

Induction of chromosomal instability in colonic cells by the human polyomavirus JC virus.

Most colorectal cancers display chromosomal instability, which is characterized by gross chromosomal rearrangements, loss of heterozygosity and aneuploidy. We have previously demonstrated a link between JC virus strains Mad-1 and Delta98 and colorectal cancer. Others have also associated the virus to the induction of colon cancer and aneuploid brain tumors by producing a highly tumorigenic protein named T antigen (TAg), which binds to beta-catenin and inactivates key proteins such as p53. The aim is to demonstrate that JC virus is capable of inducing chromosomal instability in colonic cells. We used the human colon cancer cell line RKO as a model. The cell line has wild-type p53, wild-type beta-catenin and APC and is diploid. Neuroblastoma JCI cells, which are infected with the virus, VA13 fibroblasts, which are transformed by the SV40 TAg, were used as positive controls. HCT116, which has mutated beta-catenin, and SW480, which is a model of CIN, were also used as controls. The genomes of the Mad-1 and Delta98 strains were transfected into cells. As negative controls we used pUC or no plasmids. Cells were collected at 0, 7, 14, and 21 days after transfection. PCR was used for the detection of TAg and the regulatory region DNA sequences at different time frames and Southern blot of whole genomic extracts for viral DNA integration into the host genome. Immunofluorescence and Western blot were performed for TAg, viral capsid proteins, and nuclear beta-catenin expressions, whereas coimmunoprecipitation was used to detect protein interactions. Karyotype analysis and electron microscopy were performed to seek chromosomal instability and cell abnormalities, respectively. Retention of viral sequences was observed for Mad-1- and Delta98-transfected RKO cells at all time frames with PCR only, whereas Southern blot analysis showed nonintegrated sequences at T7 alone. TAg and capsid protein expressions, as well as increased p53 and nuclear beta-catenin, were observed between T0 and T7 for Mad-1 and Delta98 alone. Also, interaction between TAg and both p53 and beta-catenin was also observed between T0 and T7. Chromosomal instability, characterized by chromosomal breakage, dicentric chromosomes, and increasing ploidy, was observed at all time frames for Mad-1 and Delta98, as well as cell abnormalities. In conclusion, we demonstrate that JC virus Mad-1 and Delta98 are able to induce chromosomal instability in colonic cells with a hit and run mechanism that involves an early interaction with beta-catenin and p53.

Antigens, Viral, Tumor↗
PubMed2005

[Arthroscopic treatment of traumatic anterior glenohumeral instability].

The main pathology in traumatic anterior instability of the shoulder is a Bankart lesion and capsuloligamentous laxity. Success in the treatment of glenohumeral instability mainly relies on an anatomical attachment of the fibrocartilaginous labrum and restoration of tension of the capsuloligamentous structures. Suture anchors are preferred for the fixation of soft tissues. Excessive capsular laxity can be treated by capsular plication or thermal capsulorrhaphy. Arthroscopy enables examination and repair of the glenohumeral structures, with several advantages over open techniques, including less morbidity and pain, shorter hospitalization, better cosmetic appearance, and a lower complication rate. These advantages have contributed to the growing acceptance of arthroscopic treatment in dealing with traumatic anterior glenohumeral instability. Moreover, its success rate has increased thanks to advances in technology and surgical techniques. Yet, appropriate selection of patients, the quality of capsulolabral structures, coexisting pathologies, and experience on the part of the surgeon are important factors in the success of arthroscopic treatment of anterior shoulder instability. This paper discusses the rationale for a treatment algorithm for arthroscopic applications together with recommendations about anterior instability of the shoulder.

Arthroscopy↗