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Discrete scale invariance, which corresponds to a partial breaking of the scaling symmetry, is reflected in the existence of a hierarchy of characteristic scales l₀,l₀λ,l₀λ²,…, where λ is a preferred scaling ratio and l₀ a microscopic cut-off. Signatures of discrete scale invariance have recently been found in a variety of systems ranging from rupture, earthquakes, Laplacian growth phenomena, "animals" in percolation to financial market crashes. We believe it to be a quite general, albeit subtle phenomenon. Indeed, the practical problem in uncovering an underlying discrete scale invariance is that standard ensemble averaging procedures destroy it as if it was pure noise. This is due to the fact, that while λ only depends on the underlying physics, l₀ on the contrary is realization-dependent. Here, we adapt and implement a novel so-called "canonical" averaging scheme which re-sets the l₀ of different realizations to approximately the same value. The method is based on the determination of a realization-dependent effective critical point obtained from, e.g., a maximum susceptibility criterion. We demonstrate the method on diffusion limited aggregation and a model of rupture.

We present a rare case of bilateral extensor pollicis longus tendon rupture in a professional football goalkeeper following steroid injection for extensor tenosynovitis. The potential pathogenesis mechanisms are discussed.

Closed flexor pulley rupture of the thumb is extremely rare. We report a case with this condition. The anatomic and biomechanical studies, clinical and operative finding as well as the management of the closed flexor pulley rupture of the thumb are discussed.

The purpose of this study is to identify a possible correlation between statin administration and incidence of spontaneous distal biceps tendon ruptures. We retrospectively reviewed 104 patients with distal biceps tendon rupture that were treated surgically from 2004 to 2010, 102 males and two females with mean age 47 years (range, 22–78). Patients were divided based on the mechanism of injury and statin administration. After statistical analysis, it was found nearly two times more likely to have spontaneous distal biceps tendon rupture with use of statins. Patients in Group 1 (spontaneous tendon rupture) compared to Group 2 (provoked tendon rupture) were older, had weaker postoperative strength but similar postoperative ROM. Patients taking statins compared to those that were not taking statins were older, had same postoperative strength and similar postoperative ROM. Based on the results of our study we conclude that there is a trend of association of spontaneous distal biceps tendon ruptures with statin administration.

Spontaneous rupture of the extensor pollicis longus (EPL) tendon is rare, and spontaneous non-traumatic rupture of both extensor pollicis longus (EPL) and extensor carpi radialis brevis (ECRB) tendons is not reported in literature. Rupture of EPL is usually associated with rheumatoid arthritis, systemic or local steroid injections, fractures of the wrist and repetitive and excessive abnormal motion of the wrist joint. We describe a case of spontaneous rupture of the EPL and ECRB tendons in a female patient, washerwoman by occupation, with no predisposing factor. Exploration of the tendons along with end to end tendon repair was done with excellent results. We describe the possible mechanism of the injury and result after one year follow up.

A complete brachioradialis tendon rupture, as an isolated incident, is extremely rare. Consequently, there is little to no literature on how this can occur and how to treat it. We present the case of a 44-year-old male with a complete, closed brachioradialis tendon rupture following a waterskiing accident. The clinical, imagining and operative findings are outlined alongside management and final outcomes. Our case highlights the effectiveness of a combined surgical and staged physiotherapy approach, for the management of a complete, closed brachioradialis tendon rupture, in an otherwise healthy man.

We report a case of flexor pollicis longus tendon rupture after arthrodesis of the trapeziometacarpal joint with headless screws using the criss-cross technique. Although flexor pollicis longus tendon rupture is a conceivable complication after the trapeziometacarpal joint arthrodesis, very few cases have rarely been reported in the literature. We should remind that screws inserted into the trapezium could lead to a rupture of the flexor pollicis longus tendon.

Purpose: The purpose of this study is to examine the collagen profile and orientation in a ruptured extensor pollicis longus (EPL) tendon, in order to better understand the collagen response to loss of tensile forces. Methods: A 76-year-old male with a history of rheumatoid arthritis required surgical reconstruction of a chronic EPL rupture using EIP tendon transfer; the refreshed tip of the distal EPL tendon, along with the intervening tubular scar and EIP tendon were further analyzed. Picrosirus red (PSR) staining was performed, and the levels of collagen isoform were determined with western blotting. Results: The results obtained from PSR staining under polarized microscopy showed thin, weakly birefringent, green fibers (collagen III-like) and thick, yellow-red, strongly birefringent fibers (collagen I-like). The arrangement was noted to be much less organized and directional in the ruptured tendon compared to the EIP tendon. Western blotting results showed the presence of collagen I, II, III, V, VI and X, with the ratio comparison to collagen I markedly different between a normal EIP tendon and the ruptured EPL tendon. Conclusion: EPL tendon rupture is accompanied by collagen disorganization and significant alteration in the collagen isoform expression, postulated to be a consequence of the loss of tensile forces.

A mathematical model for the rupture of cerebral saccular aneurysms is developed through the analysis of three-dimensional stress distribution in the aneurysm wall. We assume in this paper that a saccular aneurysm resembles a thin spherical shell (a spherical membrane), and then develop a strain-energy function valid for finite strain to analyze three-dimensional stress distribution in the aneurysm wall. We find that rupture occurs when the ratio of the wall thickness to the radius of the aneurysm is 6.1 × 10^-3. We also conclude from our analysis that rupture can occur when the ratio of thickness to radius of the parent aneurysm equals the ratio of thickness to radius of the daughter aneurysm. These findings may be helpful to the neurosurgeon for predicting the rupture potential in patients presenting with unruptured aneurysms.

The risk of rupture of intracranial saccular aneurysms is one of the leading dilemmas for patients and neurologists. Although the probability of rupture is small, the consequences of rupture are usually fatal or crippling, and a concern for the patient is whether or not to treat an existing aneurysm. In this paper, an idealized model of saccular aneurysms with assumed Fung material behavior was investigated for rupture potential when the stresses exceeded the maximum wall strength of the aneurysm wall. Numerical simulations used various levels of blood pressure, from normal to hypertensive, in order to determine correlations of aneurysm size and risk of rupture. Results showed that hypertensive individuals harboring cerebral aneurysms with a size of at least 6 mm are at risk.

Biomechanical analyses can be used to better understand the rupture risk of abdominal aortic aneurysms (AAAs) on a patient-specific basis using vascular geometries obtained from medical imaging. Methodologies of varying complexity are used to estimate the unloaded state of the imaged vessel to provide a reference configuration for finite element simulations. In this work, we compare the implementation and results of two of these methods, one based on geometric scaling and the other using an iterative determination of unloaded vessel geometry. We find that the two methods result in significantly different stress predictions, and that the iterative method offers superior geometric accuracy. Our findings lend context to the variation in finite element results presented in the AAA stress analysis literature.

Dielectric elastomer (DE) transducers usually undergo large deformation, as well as possess hyperelastic and viscoelastic behaviors. This paper presents an experimental study of rupture behavior of acrylic DE (3M-VHB 9473) membranes with various stretching rates, specimen dimensions and initial flaw sizes. The force–displacement curves, crack propagation behaviors of specimens subjected to pure-shear loading are investigated experimentally. It is observed that different stretching rate and initial flaw size drastically affect the critical rupture force and crack propagating velocity. Finite element analysis is carried out to calculate the strain distribution and the J integral.

This paper presents a simplified technique to simulate strong ground motion from a finite source of an earthquake. The simplified technique is based on modifications made in the semi empirical technique given by Midorikawa [1993] and later modified by Joshi and Midorikawa [2004]. Modifications in this technique have been made to consider the effect of radiation pattern and seismic moment of the target earthquake. The coastal region of Sumatra Island was struck by a great earthquake of magnitude 9.0 (M_w) on 26th December, 2004. This earthquake is known for its release of high amount of energy and the devastating Tsunami. This earthquake was recorded at several broadband stations including a nearest broadband station located in Indonesia. The source of this earthquake is modeled by a finite rectangular rupture plane. Various locations of nucleation point and different values of rupture velocity have been tested before finalizing the rupture responsible for this earthquake. Iterative modeling and comparison of simulated and observed record due to final model suggests that the rupture initiated at the western end of the rupture plane at a depth of 38 km and started propagating in all direction with a rupture velocity of 3.0 km/s. The final model has been used to simulate record at MDRS and VISK stations located at the coastal region of India and simulated records are compared with observed records at these stations. The comparisons confirm the suitability of final model for predicting strong ground motion and the efficacy of the approach in modeling great earthquake. Strong ground motion has been simulated for the Sumatra earthquake of 26th December, 2004 at various hypothetical stations surrounding the final model of rupture plane. The distribution of peak ground acceleration in the near source region has been computed from simulated record at these stations. The isoacceleration contours shows that high peak acceleration zones of the order of > 2 g are observed in the source zone of this earthquake which gradually decreases with distance. Using the parameters of final model of the Sumatra earthquake a great hypothetical earthquake at northern segment of Andaman ridge has been modeled and records have been simulated at Port Blair (POR) station located in the Andaman Island, India. The simulated records shows that peak ground acceleration of the order of 1.4 g can be observed at POR station due to a hypothetical earthquake in the Andaman Island suggesting high seismic hazard in this region.

Closed flexor tendon ruptures in the little finger can be caused by fracture or nonunion of the hook of the hamate, but no case of the disorder secondary to the sclerosis and thinning of the hamate hook has been reported. We report two rare cases with this complication due to rough surface of the hamate hook. Carpal tunnel view radiographs and computed tomography showed the sclerosis and thinning of the hook.

Spontaneous ruptures of the flexor carpi radialis tendon (FCR) are rare and associated with systemic inflammatory diseases, localized tendinopathy related to scaphotrapezial-trapezoidal arthritis, or chronic immunosuppression from corticosteroids. While most cases do not require operative intervention, some patients develop weakness, impaired range of motion, and persistent pain. Previously reported surgical options include synovectomy, tendon stump resection, and osteophyte removal. We describe a surgical technique for patients with persistent symptomatology following FCR rupture in which the FCR is transposed end-to-side to the palmaris longus tendon. Three cases using this technique are presented with follow-up of 4–9 months that were collected at Lenox Hill Hospital. All three patients did well regarding specific outcome measures: grip strength, range of motion, and functional activity. FCR transfer to palmaris is an alternative to other surgical options for the spontaneous rupture of the FCR tendon in patients who remain symptomatic despite a course of non-operative therapy.

We report an avulsion fracture at the base of the third metacarpal involving the extensor carpi radialis brevis insertion and a resulting complication of attritional rupture of the extensor indicis proprius tendon and the extensor digitorum communis to the index finger, in a 67-year-old man.

Background: The single looped suture modified Lim/Tsai technique is widely used for flexor tendon repairs. It has been shown to possess better biomechanical properties and require less repair time per tendon as compared to the double looped suture original Lim/Tsai technique. However, there is no clinical data on the modified technique.

Methods: The retrospective study included zone 2 flexor tendon repairs made using the modified Lim/Tsai technique from January 2008 to December 2014. Clinical outcome was assessed using the revised Strickland and Glogovac criteria, which categorises repairs based on the total active motion of the repaired digit.

Results: Sixty-two patients with 74 digits were included. The overall mean total active motion was 122°. The overall satisfactory outcome of the modified Lim/Tsai technique was 81.1%. The rupture rate of the modified Lim/Tsai technique was 2.7%. Using multivariate linear regression model, we found that outcomes were negatively influenced by subzone 2C and crush/saw injuries, but not by concomitant neurovascular injuries or post-operative follow-up duration.

Conclusions: Based on this retrospective study of patients with zone 2 flexor tendon injuries, the clinical outcomes of modified and original Lim/Tsai techniques are comparable. As such, there is no clinical evidence favouring one over the other.

Background: Flexor tendon repair carries a significant risk for complications, which often leads to revision surgery. The purpose of this study was to assess the effect of different factors on the risk for major complications patients undergoing a primary end-to-end flexor tendon repair and early passive mobilization regimen (Kleinert protocol).

Methods: Between January 2000 and September 2009, a total of 312 patients underwent a flexor tendon repair at out institution. We excluded patients whose injury was self-inflicted or secondary to a rheumatic disease or a fall leaving 187 patients with 325 injured tendons for the study.

Results: 152 (81.7%) patients were male and 34 (18.3%) females. Mean age of the patients was 32.7 years (SD 14.4, range 11 to 73). The fifth ray was most commonly affected. The majority of the injuries were located in zone II. Median delay to surgery was 3 days. Complications were observed in 34 patients (18.2%). Univariable analysis showed that patient age, mechanism of injury, injured ray, delay to surgery between three and seven days, and greater suture thickness were associated with increased risk of complications. In the subsequent multivariable analysis, only the mechanism of injury and delay to surgery remained as significant risk factors for major complications.

Conclusions: We conclude that complications after flexor tendon repair may be reduced by appropriate timing of the surgery. Delay to surgery lasting between three and seven days seems to be associated with increased risk for major complications.

Background: When closed ruptures of flexor tendons of fingers occur, there is often an identifiable pathology, which should be addressed in the same surgical setting as the tendon repair. The concept of “spontaneous” tendon rupture, occurring in the absence of identified pathology, however, has also been reported in a significant number of papers. This controversy has prompted us to do a review of the existing literature.

Methods: We did a review of cases of closed ruptures of the flexor digitorum profundus (FDP) of the little finger in existing literature. Fifty-three publications were retrieved by searching “FDP tendon rupture” and “little finger” using PubMed database. We analyzed data such as the zone of rupture noted intra-operatively; and any precipitating factors, pathology or trauma. We also conducted a review on papers which discussed the concept of “spontaneous rupture”.

Results: Fifty-three publications were retrieved. There were 8 cases of ruptures in Zone I; 2 in Zone II; 30 in Zone III; 59 in Zone IV and 5 in Zone V. Majority of cases were associated with an element of trauma of varying severity, or pathology. A precipitating cause was not documented in 12 cases. Amongst all 36 cases of ruptures labelled as “spontaneous”, only 1 case was truly “spontaneous” without any associated trauma or pathology.

Conclusions: Most reports labeled as spontaneous rupture occurred in Zone III, where tendon ruptures are rare. There are documented pathological causes or evidence of trauma to most of these cases. We conclude these ruptures may have been mislabeled as spontaneous ruptures. Bearing in mind the propensity for tendon excursion, we suspect the lack of documentation of exploration in proximal zones contributed to this mislabeling. Understanding this concept of non-spontaneity to most tendon ruptures and the common sites of rupture or pathology is crucial for a surgeon to make strategic incisions and minimize future recurrence.

We report a case of complete laceration of both flexor tendons in the dominant ring finger of a young male caused by a closed volar fracture fragment of the proximal phalanx. Careful clinical examination, reasonable index of suspicion and ultrasound confirmation play a pivotal role in the diagnosis and surgical planning of this rare yet consequential injury. Good outcomes can be achieved from the surgical management and rehabilitation of both soft tissue and bony injuries when planning of surgical approaches and fixation techniques are facilitated by an accurate pre-operative diagnosis.