Outcomes analysis of anterior and lateral approach for open repair of hip abductor tendons.

BACKGROUND: Gluteal tendons tears are increasingly being recognised as a cause of recalcitrant trochanteric pain, but there is a paucity of robust studies analysing the type of tears, results and predictors of outcome. METHODS: Patients with gluteal tendon tears resistant to conservative treatment who underwent isolated open repair (IR) or total hip arthroplasty and concomitant repair (THA+repair) with a minimum 1-year follow-up were retrospectively assessed separately. Type of tear, surgical approach, and fixation methods were registered. Complications and postoperative outcomes were analysed: visual analogue scale (VAS) of pain, VAS satisfaction, and activity level. Univariate regressions and multivariable models were developed. RESULTS: 90 cases were included: 62 cases underwent IR and 28 cases THA+repair, with an average follow-up of 3.9 years and 2.6 years, respectively. 13 complications were found (n = 5 IR, n = 8 THA+repair), including 9 re-operations (n = 4 IR, n = 5 THA+repair). Mean VAS pain score was 3.02 (SD 2.74) for the IR and 2.32 (SD 2.43) for THA+repair group. Mean VAS satisfaction was 7.09 (SD 3.07) and 7.68 (SD 2.71) for the IR and THA+repair group, respectively. In the IR group 61.4% returned to all pre-injury activities, whereas in the THA+repair group 79% did. Full-thickness tears had higher VAS pain scores (p = 0.0175), and there was trend (p > 0.05) towards higher complications, re-tears and lower VAS satisfaction in this type of tears in both groups. No statistically significant differences were found in outcomes when comparing THA+repair through direct anterior (DAA) with lateral approach (LA). CONCLUSIONS: Isolated gluteal tendon repair or THA+repairs seem to be safe procedures with high levels of satisfaction at short- to mid-term follow-up. The presence of a full-thickness tear is a predictor of inferior outcomes.

Optical and Thermal Design and Analysis of Phase-Change Metalenses for Active Numerical Aperture Control.

The control of a lens's numerical aperture has potential applications in areas such as photography and imaging, displays, sensing, laser processing and even laser-implosion fusion. In such fields, the ability to control lens properties dynamically is of much interest, and active meta-lenses of various kinds are under investigation due to their modulation speed and compactness. However, as of yet, meta-lenses that explicitly offer dynamic control of a lens's numerical aperture have received little attention. Here, we design and simulate active meta-lenses (specifically, focusing meta-mirrors) using chalcogenide phase-change materials to provide such control. We show that, operating at a wavelength of 3000 nm, our devices can change the numerical aperture by up to a factor of 1.85 and operate at optical intensities of the order of 1.2 × 109 Wm-2. Furthermore, we show the scalability of our design towards shorter wavelengths (visible spectrum), where we demonstrate a change in NA by a factor of 1.92.

Responsive robotic prey reveal how predators adapt to predictability in escape tactics.

To increase their chances of survival, prey often behave unpredictably when escaping from predators. However, the response of predators to, and hence the effectiveness of, such tactics is unknown. We programmed interactive prey to flee from an approaching fish predator (the blue acara, Andinoacara pulcher) using real-time computer vision and two-wheeled robots that controlled the prey's movements via magnets. This allowed us to manipulate the prey's initial escape direction and how predictable it was between successive trials with the same individual predator. When repeatedly exposed to predictable prey, the predators adjusted their behavior before the prey even began to escape: prey programmed to escape directly away were approached more rapidly than prey escaping at an acute angle. These faster approach speeds compensated for a longer time needed to capture such prey during the subsequent pursuit phase. By contrast, when attacking unpredictable prey, the predators adopted intermediate approach speeds and were not sensitive to the prey's escape angle but instead showed greater acceleration during the pursuit. Collectively, these behavioral responses resulted in the prey's predictability having no net effect on the time taken to capture prey, suggesting that unpredictable escape behavior may be advantageous to prey in fewer circumstances than originally thought. Rather than minimizing capture times, the predators in our study appear to instead adjust their behavior to maintain an adequate level of performance during prey capture.

Medial soft-tissue complex of the knee: Current concepts, controversies, and future directions of the forgotten unit.

The medial side of the knee is comprised of ligaments, myotendinous and meniscal structures that work as a unit to stabilize the joint. The superficial medial collateral ligament is its core structure. Still, all elements of the medial side have load-sharing relationships, leading to a cascade of events in the scenario of insufficiency of any of them. Understanding the medial soft tissue structures as part of a unit is of utmost importance because the most common ligaments damaged in knee injuries belong to it. Surprisingly, there is a lack of high-level evidence published around the issue, and most studies focus on the superficial medial collateral ligament, overlooking the complexity of these injuries. Acknowledging the consequences for joint biomechanics and treatment outcomes, interest in this area is growing between researchers. Emerging evidence may become a game-changer in the future management of these injuries. Based on a thorough research of published literature, this review provides a current biomechanical concepts and clinical guidance to treat these injuries.

Single Hit Energy-resolved Laue Diffraction.

In situ white light Laue diffraction has been successfully used to interrogate the structure of single crystal materials undergoing rapid (nanosecond) dynamic compression up to megabar pressures. However, information on strain state accessible via this technique is limited, reducing its applicability for a range of applications. We present an extension to the existing Laue diffraction platform in which we record the photon energy of a subset of diffraction peaks. This allows for a measurement of the longitudinal and transverse strains in situ during compression. Consequently, we demonstrate measurement of volumetric compression of the unit cell, in addition to the limited aspect ratio information accessible in conventional white light Laue. We present preliminary results for silicon, where only an elastic strain is observed. VISAR measurements show the presence of a two wave structure and measurements show that material downstream of the second wave does not contribute to the observed diffraction peaks, supporting the idea that this material may be highly disordered, or has undergone large scale rotation.

Nanosecond white-light Laue diffraction measurements of dislocation microstructure in shock-compressed single-crystal copper.

Under uniaxial high-stress shock compression it is believed that crystalline materials undergo complex, rapid, micro-structural changes to relieve the large applied shear stresses. Diagnosing the underlying mechanisms involved remains a significant challenge in the field of shock physics, and is critical for furthering our understanding of the fundamental lattice-level physics, and for the validation of multi-scale models of shock compression. Here we employ white-light X-ray Laue diffraction on a nanosecond timescale to make the first in situ observations of the stress relaxation mechanism in a laser-shocked crystal. The measurements were made on single-crystal copper, shocked along the [001] axis to peak stresses of order 50 GPa. The results demonstrate the presence of stress-dependent lattice rotations along specific crystallographic directions. The orientation of the rotations suggests that there is double slip on conjugate systems. In this model, the rotation magnitudes are consistent with defect densities of order 10(12) cm(-2).

Successful early mobilization of major cuff repair using a suture post.

Repair of massive rotator cuff tears in the elderly can be challenging because of degenerative, retracted, and contracted tendons producing an extensive defect. The quality of the tendon and particularly the bone of the proximal humerus is an inherent weakness in the repaired construct. We report a method that secures the rotator cuff to a fixation post placed in cortical bone at the surgical neck of the humerus, bypassing the weakest point. This is an evolution of techniques designed to fix to the greater tuberosity. We reviewed 32 repairs (16 men and 14 women; mean age, 68 years) with a minimum of 2 years' follow-up (mean, 4.3 years). Constant scores improved from a mean of 27.9 preoperatively to 78.2 postoperatively. Pain scores improved from 8.2 to 1.9, with 87% of patients being satisfied with the results of surgery. This is a robust construct that is easily learned and able to solve a technical problem.

Consequences of diagnostic delays in slipped capital femoral epiphysis.

Delay in diagnosis of slipped capital femoral epiphysis has important implications with regard to slip severity and long-term hip outcomes. The aims of this review were to identify the incidence of delayed diagnosis of slipped capital femoral epiphysis in the hospital to which the authors are affiliated, and the causes for such delays. A retrospective review was conducted of all patients admitted to the Women's and Children's Hospital in Adelaide between January 1997 and October 2004 with a diagnosis of slipped capital femoral epiphysis. The inpatient and outpatient medical records for each patient were analysed to clarify the history of presentation and identify those patients with a delayed diagnosis. All radiographs were reviewed and the severity of the slip graded according to Southwick's classification. One hundred and two patients were included in this review, of which 20 had a delayed diagnosis and 25 a late presentation. Of the 20 (19.6%) patients who had a delayed diagnosis in this series, a minimum of 2 weeks elapsed between presentation to a health professional and diagnosis of slipped capital femoral epiphysis. Eight patients had seen their local doctor but the diagnosis was not made. The remaining 12 patients with delayed diagnosis had not seen a medical practitioner and had self-referred to a chiropractor or a physiotherapist. All of these patients underwent hip manipulation prior to diagnosis. There was a significant relationship between delay in diagnosis and an increased slip severity, when compared with both the remainder of this series and the late presentation group. Knee or distal thigh pain in slipped capital femoral epiphysis remains the commonest pitfall in diagnosis for local doctors, as well as mild slips being missed on radiograms by inexperienced surgeons or radiologists. An increasing presentation of adolescents with this disorder to allied health professionals for initial management warrants a broader education strategy than has been previously advocated. Slipped capital femoral epiphysis remains an enigmatic disorder; consequently delayed diagnosis of this condition is not likely to disappear. Despite this, the medical community must strive toward early diagnosis through continued education and vigilance.