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PubMed2005

Capsulodesis for the treatment of chronic scapholunate instability.

PURPOSE: Scapholunate (SL) instability is the most common form of carpal instability. The treatment of this disorder is challenging and varying treatment options have been described. The purpose of this study was to examine the intermediate-term results of dorsal capsulodesis for cases of chronic SL dissociation. METHODS: A retrospective analysis was conducted that examined all dorsal capsulodesis procedures performed for chronic SL dissociation between January of 1990 and February of 2000. Wrist pain had to be present for greater than 3 months. Patients had to have a minimum follow-up period of 2 years for inclusion in the study. Thirty-one patients were identified with isolated chronic SL dissociation. Of the 31 patients 18 had dynamic carpal instability and 13 had static carpal instability. The time from injury to surgery averaged 20 months. The follow-up period averaged 54 months (range, 24-96 mo). All patients had a dorsal capsulodesis procedure using either a Blatt or Mayo technique. Results were reviewed clinically and radiologically. Static and dynamic groups were compared with a Student t test. RESULTS: There was a 20% decrease in wrist motion after capsulodesis. There was no improvement in grip strength after surgery. Most patients had improvement in pain but only 2 patients were completely pain free. Radiographically the SL gap increased over time from 2.7 mm before surgery to 3.9 mm at the final follow-up evaluation. The SL angle also increased from 56 degrees before surgery to 62 degrees on final follow-up evaluation. There was no statistical difference in overall wrist motion, grip strength, or wrist score between the dynamic and static groups. The time to surgery and age had no significant effect on overall outcome. CONCLUSIONS: Dorsal capsulodesis provided pain relief for patients with both dynamic and static SL instability. Although pain was improved it was not completely resolved in the majority of cases. From a radiographic perspective dorsal capsulodesis did not provide maintenance of carpal alignment in cases of chronic SL dissociation.

Adolescent↗
PubMedDate not supplied

An assessment of the interexaminer reliability of tests for shoulder instability.

Accurate noninvasive clinical tests of shoulder instability are important in assessing and planning treatment for glenohumeral joint instability. An interexaminer agreement trial was undertaken to estimate the reliability of commonly used clinical tests for shoulder instability. Thirteen patients with a history suggestive of instability, who had been referred to a shoulder specialist for treatment of their symptomatic shoulders, were examined by four examiners of differing experience. Good to excellent interexaminer agreement was found for most variations of the load-and-shift test, with the best agreement in the 90 degrees abducted position for the anterior direction (intraclass correlation coefficient [ICC] = 0.72) and in the 0 degrees abducted position for the posterior (ICC = 0.68) and inferior (ICC = 0.79) directions. Fair to good interexaminer reliability was found for the sulcus sign (ICC = 0.60). With regard to the provocative tests, agreement was best when apprehension was used as the criterion for a positive test and was better for the relocation (ICC = 0.71) and release tests (ICC = 0.63) than for the apprehension (ICC = 0.47) and augmentations tests (ICC = 0.48). Reliability was poor (ICC < 0.31) when pain was used as the criterion for a positive test. These results indicate that the load-and-shift, sulcus, and provocative tests (apprehension, augmentation, relocation, and release) are reliable clinical tests for instability in symptomatic patients when care is taken with respect to arm positioning and if apprehension is used as the criterion for a positive provocative test.

Adolescent↗
PubMedDate not supplied

Posterior capsulolabral reconstruction in posterior shoulder instability: deltoid saving.

To determine the efficacy of an open posterior capsulolabral reconstruction (PCLR) with a posterior deltoid-saving approach, 30 PCLRs in 29 patients with unidirectional posterior instability were reviewed retrospectively. The mean follow-up period was 30 months (range, 25-59 months). Posterior capsular redundancy was observed in all cases, but a posteroinferior labral tear was found in only 5. Posterior capsular thinning developed in 6 patients. According to the Rowe scale, 24 shoulders were rated as excellent, 1 as good, 2 as fair, and 3 as poor. The modified American Shoulder and Elbow Surgeons score at last follow-up was 91. During follow-up, recurrence of instability was observed in 4 cases, including 3 cases of voluntary instability. The overall recurrence rate was 13.3%, but the success rate was 92.6% when cases of voluntary instability were excluded. Whereas the midterm clinical results of PCLRs were satisfactory, the risk of recurrence was very high in patients with voluntary posterior instability, even though some subjective improvement could be obtained through a PCLR.

Adolescent↗
PubMed2005

Subjective and objective descriptors of clinical lumbar spine instability: a Delphi study.

Accurate ability to diagnose lumbar spine clinical instability is controversial for numerous reasons, including inaccuracy and limitations in capabilities of radiographic findings, poor reliability and validity of clinical special tests, and poor correlation between spinal motion and severity of symptoms. It has been suggested that common subjective and objective identifiers are specific to lumbar spine clinical instability. The purpose of this study was to determine if consensual, specific identifiers for subjective and objective lumbar spine clinical instability exist as determined by a Delphi survey instrument. One hundred and sixty eight physical therapists identified as Orthopaedic Clinical Specialists (OCS) or Fellows of the American Academy of Orthopaedic Manual Physical Therapists participated in three Delphi rounds designed to select specific identifiers for lumbar spine clinical instability. Round I consisted of open-ended questions designed to provide any relevant issues. Round II allowed the participants to rank the organized findings of Round I. Round III provided an opportunity to rescore the ranked variables after viewing other participant's results. The results suggest that those identifiers selected by the Delphi experts are synonymous with those represented in related spine instability literature and may be beneficial for use during clinical differential diagnosis.

Adult↗
PubMed2004

Radiation-induced chromosomal instability and gene expression profiling: searching for clues to initiation and perpetuation.

Radiation-induced genomic instability (RIGI) manifests in the progeny of cells surviving ionizing radiation (IR), and can be measured using such endpoints as delayed mutation, micronuclei formation, and chromosomal instability. The frequency of RIGI is relatively high, exceeding the gene mutation rate of IR by orders of magnitude, leading to conjecture that a gene mutation is not the cause of the phenotype. We have started to explore whether differential gene expression patterns are associated with the instability phenotype, in order to shed light on its initiation and perpetuation. Using GM10115 human-hamster hybrid-derived chromosomally stable and radiation-induced unstable clones, gene expression patterns were analyzed using microarray analysis. Two methods were used to find differentially expressed genes, and all candidate genes identified by these methods were under-expressed relative to the chromosomally stable reference sample. Among this set differentially expressed genes identified were two candidates with a relationship to the ubiquitin/proteasome pathway. While follow-up gene expression analyses have confirmed the under-expression of these two genes in some of our chromosomally unstable clones, preliminary functional studies have been unable to demonstrate a link to instability. It is anticipated that as we apply this technology to the study of radiation-induced genomic instability, clues to its onset will be revealed, ultimately contributing to a greater understanding of the mechanisms of radiation carcinogenesis.

Animals↗
PubMed2004

A biological-based model that links genomic instability, bystander effects, and adaptive response.

This paper links genomic instability, bystander effects, and adaptive response in mammalian cell communities via a novel biological-based, dose-response model called NEOTRANS3. The model is an extension of the NEOTRANS2 model that addressed stochastic effects (genomic instability, mutations, and neoplastic transformation) associated with brief exposure to low radiation doses. With both models, ionizing radiation produces DNA damage in cells that can be associated with varying degrees of genomic instability. Cells with persistent problematic instability (PPI) are mutants that arise via misrepair of DNA damage. Progeny of PPI cells also have PPI and can undergo spontaneous neoplastic transformation. Unlike NEOTRANS2, with NEOTRANS3 newly induced mutant PPI cells and their neoplastically transformed progeny can be suppressed via our previously introduced protective apoptosis-mediated (PAM) process, which can be activated by low linear energy transfer (LET) radiation. However, with NEOTRANS3 (which like NEOTRANS2 involves cross-talk between nongenomically compromised [e.g., nontransformed, nonmutants] and genomically compromised [e.g., mutants, transformants, etc.] cells), it is assumed that PAM is only activated over a relatively narrow, dose-rate-dependent interval (D(PAM),D(off)); where D(PAM) is a small stochastic activation threshold, and D(off) is the stochastic dose above which PAM does not occur. PAM cooperates with activated normal DNA repair and with activated normal apoptosis in guarding against genomic instability. Normal repair involves both error-free repair and misrepair components. Normal apoptosis and the error-free component of normal repair protect mammals by preventing the occurrence of mutant cells. PAM selectively removes mutant cells arising via the misrepair component of normal repair, selectively removes existing neoplastically transformed cells, and probably selectively removes other genomically compromised cells when it is activated. PAM likely involves multiple pathways to apoptosis, with the selected pathway depending on the type of cell to be removed, its cellular environment, and on the nature of the genomic damage.

Animals↗
PubMed2006

Inviting instability: Transposable elements, double-strand breaks, and the maintenance of genome integrity.

The ubiquity of mobile elements in mammalian genomes poses considerable challenges for the maintenance of genome integrity. The predisposition of mobile elements towards participation in genomic rearrangements is largely a consequence of their interspersed homologous nature. As tracts of nonallelic sequence homology, they have the potential to interact in a disruptive manner during both meiotic recombination and DNA repair processes, resulting in genomic alterations ranging from deletions and duplications to large-scale chromosomal rearrangements. Although the deleterious effects of transposable element (TE) insertion events have been extensively documented, it is arguably through post-insertion genomic instability that they pose the greatest hazard to their host genomes. Despite the periodic generation of important evolutionary innovations, genomic alterations involving TE sequences are far more frequently neutral or deleterious in nature. The potentially negative consequences of this instability are perhaps best illustrated by the >25 human genetic diseases that are attributable to TE-mediated rearrangements. Some of these rearrangements, such as those involving the MLL locus in leukemia and the LDL receptor in familial hypercholesterolemia, represent recurrent mutations that have independently arisen multiple times in human populations. While TE-instability has been a potent force in shaping eukaryotic genomes and a significant source of genetic disease, much concerning the mechanisms governing the frequency and variety of these events remains to be clarified. Here we survey the current state of knowledge regarding the mechanisms underlying mobile element-based genetic instability in mammals. Compared to simpler eukaryotic systems, mammalian cells appear to have several modifications to their DNA-repair ensemble that allow them to better cope with the large amount of interspersed homology that has been generated by TEs. In addition to the disruptive potential of nonallelic sequence homology, we also consider recent evidence suggesting that the endonuclease products of TEs may also play a key role in instigating mammalian genomic instability.

Animals↗
PubMed2005

Replication fork dynamics and dynamic mutations: the fork-shift model of repeat instability.

Gene-specific repeat instability is responsible for >36 human diseases. Active instability varies in a tissue-, developmental stage- and locus-specific manner and occurs in both proliferative and non-proliferative cells. In proliferative cells, DNA replication can contribute to repeat instability either by switching the direction of replication, which changes the repeat sequence that serves as the lagging-strand template (origin switching), or by shifting the location of the origin of replication without altering the replication direction (origin shifting). We propose that changes in the dynamics of replication-fork progression, or architecture, will alter the location of the repeat within the single-stranded lagging-strand template, thereby influencing instability (fork shifting). The fork-shift model, which does not require origin relocation, is influenced by cis-elements and trans-factors associated with driving and maintaining replication forks. The fork-shift model can explain some of the complex behaviours of repeat instability because it is dynamic and responsive to variations in epigenomic and locus activity.

DNA Polymerase III↗
PubMed2001

Hinged elbow fixation for recurrent instability following fracture dislocation.

The purpose of this study was to evaluate the use of an articulated external fixator of the elbow in the management of instability after fracture dislocation. We retrospectively reviewed results of eight patients treated with an articulated external fixator between 1998 and 1999. Study inclusion criteria included recurrent/chronic dislocation following fracture dislocation. Patients were divided into two groups based on the onset of instability. Group I (n=3) included patients with acute instability. The indication for use of the articulated external fixator in this subset of patients was the inability to accomplish complete osseous and ligamentous repair secondary to high degrees of comminution and/or severe soft tissue defects. Group II (n=5) patients presented at least 6 weeks after the original injury; the indication for use of the external fixator was inability to maintain joint congruity following open reduction. Application of the fixator was performed as an alternative to reconstruction of both medial and lateral ligaments. Follow-up at 1.5 years consisted of radiographs, occupational therapy ROM and DASH outcome measurement. At follow-up, Group I patients maintained an average total arc of motion of 120 degree, average flexion contracture: 25 degree, average pronation: 90 degree, and average supination: 67 degree. Group II patients had an average total arc of motion of 84 degree, average flexion contracture: 33 degree, average pronation: 68 degree, and average supination: 43 degree. Radiographic appearance of patients in both groups revealed a congruent humero-ulnar joint. DASH forms indicated patients experienced mild difficulty with activities of daily living. In conclusion, global instability of the elbow after fracture dislocation remains a difficult problem. High-energy injuries may result in an inability to maintain a congruous humero-ulnar articulation despite osteosynthesis and direct repair of the medial collateral ligament (MCL) and LUCL. When repair of the coronoid process and MCL is not feasible secondary to excessive comminution or soft tissue defect, the use of an articulated external fixator permits concentric stability and reduction of the humero-ulnar articulation. In cases of chronic instability, application of an articulated external fixator provides an alternative to complete osseous and ligamentous reconstruction. In both acute and chronic situations, the use of the articulated elbow fixator results in most patients regaining very good functional use of the elbow.

Adult↗
PubMed2001

Knee: axial instability.

The long term results of total knee replacement are among the most successful of any orthopedic procedure; however, certain patterns of failure have been identified including varus-valgus instability and anterior-posterior instability in flexion. While trauma may cause acute ligamentous injury that results in instability, the majority of cases likely result from intraoperative decisions that result in malalignment and inadequate soft tissue balancing. Failure to restore medial-lateral soft tissue balance with symmetric flexion and extension spaces may result in postoperative instability. Techniques to achieve correct soft tissue balancing and symmetric flexion and extension gaps, as well as the management of postoperative instability, are reviewed.

Arthroplasty, Replacement, Knee↗
PubMed1985

Volar intercalated segment instability as a result of spontaneous rupture of the supporting ligaments of the wrist due to longterm systemic steroid medication.

Linscheid and Dobyns (1972), in a classical article on post-traumatic instability of the wrist described two major types of instability, dorsal and volar. The dorsal intercalated segment instability (D.I.S.I.) was the more common and occurred with scapholunate dissociation and displaced scaphoid fractures. The instability occurred in these conditions as a result of the scaphoid losing its ability to support the carpus. They presented five cases of volar intercalated segment instability (V.I.S.I.) of which four were related to congenital ligament laxity and not to traumatic ligament disruption. In the one case of traumatic origin they felt that the capitolunate ligament was ruptured. However, more recent publications by Taleisnik, Prietto (1982) and Reagan, (1984) have proposed that for V.I.S.I. to occur the lunate triquetral interosseous ligament must be disrupted. We report this case as it demonstrates which ligamentous structures are torn for V.I.S.I. to occur. In addition, these ligament disruptions were pathological and occurred spontaneously as a result of longterm systemic steroid medication.

Aged↗
PubMed2000

Arthroscopic versus open Bankart repair for traumatic anterior shoulder instability.

After more than 15 years of experience, arthroscopic shoulder stabilization is becoming less controversial. Historically, recurrence rates following arthroscopic stabilization have been higher than with open stabilization. Although a negligible advantage may exist in terms of expedited postoperative rehabilitation and improved postoperative recovery of motion, critics suggest that its use in contact athletes be limited. The indications for arthroscopic stabilization are expanding, in part, because of improved understanding of the pathophysiology of shoulder instability. Understanding the mechanism of recurrent instability following arthroscopic stabilization offers clues to how physicians can prevent unsatisfactory results in the future. With newer instrumentation and the ability to thermally treat capsular tissue, coexisting pathology, such as capsular plastic deformation, rotator interval lesions, and unrecognized intra-articular pathology, can now be addressed arthroscopically. The judicious use of these techniques is warranted until long-term study results become available. Ideal patients for arthroscopic Bankart repair have a discrete Bankart lesion; a robust, well-developed IGHL; no significant capsular laxity or intraligamentous injury; and an absence of concomitant intra-articular pathology. Additional findings on MR imaging or CT evidence of a discrete labral lesion and pure unidirectional anterior instability during EUA are also good prognostic indicators for arthroscopic Bankart repair. Arthroscopic criteria that render patients less appropriate for an arthroscopic repair include capsular injury, capsular laxity, a bony Bankart lesion, glenohumeral arthritis, and a rotator cuff tear. The authors' believe that either absent or patulous, poorly developed glenohumeral ligaments represent a poor prognostic indicator for a successful outcome following standard arthroscopic Bankart repair. Individuals with poor-quality tissue are more predictably managed using open capsulorrhaphy. Patients with pathologic ligamentous laxity in the absence of a Bankart lesion or any apparent intraligamentous injury to the IGHL are also good candidates for treatment with an open capsulorrhaphy. Findings determined from a thorough physical examination, EUA, and the pathology appreciated during diagnostic arthroscopy help to appropriately choose the surgical procedure that effectively addresses pathology in patients who present with recurrent traumatic anterior instability. Patient preferences and surgical experience are important determinants of procedure selection, and current arthroscopic techniques lack the versatility to uniformly address the entire spectrum of pathology that may be associated with traumatic anterior shoulder instability. Surgeons should always be prepared to convert to an open-stabilization technique if the arthroscopic technique is deficient in addressing all pathology identified at the time of surgery.

Arthroscopy↗
PubMed1998

Arthroscopic assessment of carpal instability.

The evaluation, classification, and treatment of carpal instability continues to be one of the most controversial topics in hand surgery. One explanation is the lack of standardized findings and radiographic criteria. No good modality to date has been proposed to accurately aid in evaluating carpal instability. Wrist arthroscopy has become increasingly useful in the assessment of mechanical wrist pain. With this technology, specific patterns of injury can more accurately be identified by direct visualization. This will also aid in implementing a reproducible, less subjective means of describing wrist instability. The treatment can then be focused on management of the specific ligamentous injury responsible for the pattern of instability visualized. The following is an attempt to categorize these instability patterns as seen through arthroscopy and provide our proposed treatment options.

Arthroscopy↗
PubMed2002

Subtalar instability. Etiology, diagnosis, and management.

Subtalar instability is an evolving disorder that seems to cause a portion of chronic hindfoot instability. It can be seen as an isolated problem, or more commonly, in combination with ankle instability. There seems to be many injury mechanisms, most of which seem to involve supination of the hindfoot, and all seem to attenuate the lateral ligaments of the ankle and subtalar joints. As the condition progresses, and additional sprains occur as a result of the alteration in subtalar joint mechanics, the remaining ligaments become attenuated. There are many methods described to diagnose subtalar instability, but no conclusive test has been devised. Thus, the diagnosis must be inferred from an accurate history, physical examination, conferring radiographic studies, and failure of nonoperative management (often, for ankle instability). As with other hindfoot injuries, many patients improve with conservative measures. These measures are early (ice and immobilization) and late (bracing and proprioceptive training). When patients do not improve or cannot tolerate bracing, recent studies have shown there is a role for ligamentous reconstruction. Most procedures attempt to recreate the lateral ligament structures, including the calcaneofibular, the cervical, and the interosseous talocalcaneal ligaments, which seem to have the best stabilizing effect on the hindfoot. With the advent of newer procedures and more aggressive surgical management, there may be a role for early anatomic repair and rehabilitation.

Arthroscopy↗
PubMed2002

[Dorsal instability of the ulnar stump following distal resection: hemi extensor-carpi-ulnaris stabilization procedure].

Dorsal instability of the ulnar stump may be a complication of Darrach and Sauve-Kapandji procedures. Stabilizing procedures are numerous using flexor carpi ulnaris, extensor carpi ulnaris tendons or a combination of both tendons, the palmaris longus, and even synthetic or free grafts. The authors report nine cases of ulnar stump instability, five times post-traumatic and four as a result of rheumatoid arthritis. A tenodesis using a strip half of the extensor carpi ulnaris was performed in all these patients. Post-operatively eight patients were pain-free with in one case occasional pain after heavy work. All stumps were clinically stable. Forearm rotation and grip strength were maintained. Radiological dorsal ulnar subluxation was always reduced. Treatment of these instabilities should be preventive. When dorsal instability of the ulnar stump occurs, the half strip extensor carpi ulnaris tenodesis provides consistent satisfactory results in both arthritic and post-traumatic-related instability.

Adult↗
PubMed2003

[Development of a arthroscopic severity score for scapholunate instability].

INTRODUCTION: We report the development of an arthroscopic severity score for scapholunate instability based on dynamic testing of the scapholunate joint. METHOD: Seventy patients who had a scapholunate instability diagnosed by arthroscopy were reviewed. There were 21 static instabilities, 19 dynamic instabilities and 30 preradiographic instabilities. The arthroscopic finding was systematized. In the radiocarpal space the scapholunate interosseous ligament was seen and palpated. In the midcarpal space, the dynamic manoeuvre of dissociation was done using the examining hook. RESULTS: An arthroscopic classification was developed: in stage 0, it is impossible to put the tip of the hook between the scaphoid and the lunate; in stage 1, it is possible to put the tip of the hook between the scaphoid and the lunate; in stage 2, it is possible to create a scapholunate diastasis with the use of a twisting motion applied to the hook; in the stage 3, the 2.7-mm arthroscope passes between the scaphoid and lunate from the midcarpal to the radiocarpal space. We found 4 stage 1, 43 stage 2 and 23 stage 3. DISCUSSION: Even if other diagnostic tools such as the arthroscanner or MRI are able to diagnose scapholunate interosseous ligament tears, wrist arthroscopy is for us the Gold Standard to quantify and directly explore the scapholunate joint. The goal of the score of severity presented here is to guide the different therapeutic indications.

Adolescent↗
PubMed2005

Repeat instability: mechanisms of dynamic mutations.

Disease-causing repeat instability is an important and unique form of mutation that is linked to more than 40 neurological, neurodegenerative and neuromuscular disorders. DNA repeat expansion mutations are dynamic and ongoing within tissues and across generations. The patterns of inherited and tissue-specific instability are determined by both gene-specific cis-elements and trans-acting DNA metabolic proteins. Repeat instability probably involves the formation of unusual DNA structures during DNA replication, repair and recombination. Experimental advances towards explaining the mechanisms of repeat instability have broadened our understanding of this mutational process. They have revealed surprising ways in which metabolic pathways can drive or protect from repeat instability.

DNA Repair↗
PubMed2003

Second cancers after radiotherapy: any evidence for radiation-induced genomic instability?

Do second primary cancers in humans arise from radiation-induced somatic genomic instability after radiotherapy for the first malignancy? The amount of truly pertinent human information on this issue is sparse, leading to the conclusion that we cannot confirm or refute that instability induction by radiation is involved. However, the in vitro findings of radiation-induced genomic instability through bystander effects or increased mutation rates in cell progeny of apparently normal but irradiated cells are provocative and their transferability to human in vivo biology deserves further investigation. We describe possible animal and human studies to stimulate ideas, but the collaborative commitment of multiple large institutions to tumor tissue procurement and retrieval will be essential. In addition, detecting the temporal progression of genomic instability and identifying the salient genetic events as being radiation-induced will be pivotal. Execution of some of the studies suggested is not possible now, but applying next-generation methods could bring the concepts to fruition. As nearly one in 10 cancer diagnoses are second (or higher) malignancies, it is important to understand the contribution of radiotherapy to second cancer induction and pursue well-coordinated efforts to determine the role of induced genomic instability.

DNA Damage↗