Improve Hip Stability Research Articles

Augmented cement shelf acetabuloplasty to improve hip stability in elderly patients with recurrent hemiarthroplasty dislocations

Background The treatment of dislocated hip hemiarthroplasty in low-demand elderly patients is controversial due to poor results with closed reduction, and significant complications with exchange arthroplasty. This case series demonstrates the use of a novel, simple surgical technique for hip hemiarthroplasty containment without resorting to exchange arthroplasty. Methods Eleven patients where screw-augmented cement shelf acetabuloplasty procedures were performed were retrospectively identified. All surgeries were performed by a single attending surgeon, at a level-one trauma center, from 2015 to 2022. Previous dislocations, interventions, co-morbidities, mobility level, and posterior wall deficiency were recorded from the patient's charts. The following outcome measures were recorded: operative time, blood loss, perioperative complications, early and late infections, shelf loosening, subsequent dislocations, and the need for additional procedures. Results The median duration between hip hemiarthroplasty and shelf procedure was 56 days. The mean duration of the surgical procedure was only 63 min, and the mean blood loss was only 250 mL. There was only one instance of loosening of the cement shelf. Two patients had surgical site infections leading to sepsis and death. In two patients, the femoral head was exchanged to improve stability. All patients were allowed immediate weight bearing after the procedure. Conclusions Shelf acetabuloplasty is a simple, inexpensive, and safe procedure to salvage recurrent hip hemiarthroplasty dislocation in low-demand patients. Shorter surgical duration, relatively lower blood loss, and immediate weight bearing render this an attractive procedure for this fragile population.

The Contribution of Soft Tissue and Bony Stabilizers to the Hip Suction Seal: A Systematic Review of Biomechanical Studies

Background: Previous biomechanical studies have identified capsular closure, labral repair or reconstruction, and osteochondroplasty as important surgical interventions to improve hip stability. Purpose: To investigate the outcome metrics used to quantify hip stability and assess and measure the relative contributions of the labrum, capsule, and bone to hip stability through a quantitative analysis. Study Design: Systematic review and meta-analysis; Level of evidence, 4. Methods: PubMed and Embase databases were searched using the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Included studies evaluated cadaveric hip biomechanics related to capsular, labral, and bony management during hip arthroscopy. Studies were assessed for distraction force and distance, fluid measures, and contact forces used to quantify the suction seal. Exclusion criteria included open surgery, arthroplasty, reorientation osteotomy, or traumatic dislocation. Results: A total of 33 biomechanical studies comprising 322 hips that evaluated 1 or more of the following were included: distraction force or distance (24 studies), fluid measures (10 studies), and contact forces (6 studies). Compared with a capsulotomy or capsulectomy, capsular repair or reconstruction demonstrated greater resistance to distraction (standardized mean difference [SMD], 1.13; 95% CI, 0.46-1.80; P = .0009). Compared with a labral tear, a labral repair or reconstruction demonstrated less resistance to distraction (SMD, −0.67; 95% CI, −1.25 to −0.09; P = .02). Compared with a labral debridement, repair or reconstruction demonstrated greater resistance to distraction (SMD, 1.74; 95% CI, 1.23 to 2.26; P < .00001). No quantitative analysis was feasible from studies evaluating the effect of osseous resection due to the heterogeneity in methodology and outcome metrics assessed. Conclusion: Most biomechanical evidence supports capsulotomy repair or reconstruction to improve hip distractive stability at the end of hip arthroscopic surgery. While the repair of a torn labrum does not improve distractive resistance, it is superior to labral debridement in most biomechanical studies.

Hip Capsulolabral Complex: Anatomy, Disease, MRI Features, and Postoperative Appearance.

The hip is a uniquely constrained joint with critical static stability provided by the labrum, capsule and capsular ligaments, and ligamentum teres. The labrum is a fibrocartilaginous structure along the acetabular rim that encircles most of the femoral head. Labral tears are localized based on the clock-face method, which determines the extent of the tear while providing consistent terminology for reporting. Normal labral variants can mimic labral disease and can be differentiated by assessment of thickness or width, shape, borders, location, and associated abnormalities. The Lage and Czerny classification systems are currently the most well-known arthroscopic and imaging systems, respectively. Femoroacetabular impingement is a risk factor for development of labral tears and is classified according to bone dysmorphisms of the femur ("cam") or acetabulum ("pincer") or combinations of both (mixed). The capsule consists of longitudinal fibers reinforced by ligaments (iliofemoral, pubofemoral, ischiofemoral) and circular fibers. Capsular injuries occur secondary to hip dislocation or iatrogenically after capsulotomy. Capsular repair improves hip stability at the expense of capsular overtightening and inadvertent chondral injury. The ligamentum teres is situated between the acetabular notch and the fovea of the femoral head. Initially considered to be inconsequential, recent studies have recognized its role in hip rotational stability. Existing classification systems of ligamentum teres tears account for injury mechanism, arthroscopic findings, and treatment options. Injuries to the labrum, capsule, and ligamentum teres are implicated in symptoms of hip instability. The authors discuss the labrum, capsule, and ligamentum teres, highlighting their anatomy, pathologic conditions, MRI features, and postoperative appearance. ©RSNA, 2024 Test Your Knowledge questions for this article are available in the supplemental material.

912 An Evaluation of Outcomes in G7 Dual Mobility Cup Arthroplasty for Primary Total Hip Arthroplasty: A Single Centre Retrospective Study

Abstract Background Hip instability is one of the commonest complications of total hip replacement (THR) and remains a leading indication for revision surgery. The G7 Dual Mobility Cup (G7-DMC) was designed to improve hip stability and increase range of movement. Our study aims to look at the use of G7-DMC in patients with varying risk of dislocation, to observe rates of hip instability, as well as their short and long term post-operative outcomes. Method Between 2017 and 2021, 177 patients received a G7-DMC for primary hip arthroplasty. These patients were divided into three groups: elective surgery with low risk for dislocation, elective surgery with high risk of dislocation or THR for trauma. Outcome measures included dislocation rate, Oxford Hip Score (OHS), short- and long-term complications and revision surgery. Results One traumatic dislocation (1.9%) was seen in the high-risk group following a fall in the post-operative period, no dislocations were seen in the low-risk or trauma groups. No patients required revision surgery for dislocation or hip instability. OHS was significantly lower in the high-risk group (39.4 +/- 8.9) compared with low-risk (43.5 +/- 6.5) (P = 0.012), however no significant difference was seen against the trauma group (41.5 +/- 7.8). Long-term complications were similar in all three groups. Conclusions Despite higher rates of short-term complications and poorer OHS seen in the high-risk group of patients, no spontaneous dislocation or revision surgery for hip instability has been seen in any of the three groups. We therefore support its use in primary THR, particularly in those with high risk of dislocation.

Study on U hull modifications with concave design to improve the tourist ship stability

Stability is an important aspect that was studied in ship design as it relates to the safety of the ship when facing ocean waves. The tourist ship needed to have a good image in order to attract tourists to use its services. Good stability of the tourist ship was crucial in enhancing the image of the ship and attracting tourists to utilize its services. This research aimed to investigate the effect of concave on the U hull to improve ship stability. The study compared the stability test results of two hull designs: U hull with concave and without concave. The stability tests of both ship models were conducted through simulation methods. The simulations were performed under two conditions: when the tourist ship was empty and when it was fully loaded with passengers. The simulation results indicated that the design of the U hull with concave had a positive influence on ship stability, leading to improved stability. The concave design enhanced the ship's ability to return to its original position when encountering waves. Even in the presence of small waves, the tourist ship did not experience instability.

Combining Shelf Osteotomy With Proximal Femoral Reconstruction After Oncologic Resection

Introduction: Oncologic proximal femoral resection and reconstruction in skeletally immature children remains a formidable task due to the risk of developing hip instability with patient growth or interval leg lengthening through the prosthesis. Shelf pelvic osteotomy increases femoral head coverage and containment, and favorable long-term results have been reported in the setting of developmental dysplasia of the hip and Perthes disease. We present a technique of combining shelf osteotomy with expandable proximal femoral endoprosthesis reconstruction in pediatric limb-sparing surgery. Materials and Methods: Four surgeons at 2 centers from 2012 to 2020 performed proximal femoral reconstruction with shelf osteotomy. Data were collected retrospectively on operative technique, radiographic measurements, and complications including dislocation, subluxation, implant loosening, pain, function, and radiographic outcomes. Results: Five patients were included in the study. The mean follow-up was 49 months (range: 17 to 104 mo). The mean lateral center edge angle status postproximal femoral resection and reconstruction shelf osteotomy was 56.1 degrees (±30.5). There were no reported incidences of subluxations, dislocations, periprosthetic fractures, or soft tissue complications. The 3 patients with the longest follow-up at 3, 5, and 8 years tolerated serial lengthening of the endoprosthesis totaling 1 cm, 7.25 cm, and 9 cm, respectively, and demonstrated earlier triradiate cartilage closure in the operative side compared with the nonoperative side. All patients have returned to independent ambulation. Discussion: Combining proximal femoral reconstruction with shelf osteotomy in limb salvage pediatric orthopedic oncology may help to improve hip stability with serial lengthening and patient growth.

Wave propulsion and sea-keeping enhancement for ships in rough sea condition by flapping foils

When sailing in rough seas, ships are subject to wave excitation forces that increase drag, damage the hull structure, affect equipment operation, and even result in ship accidents. By extracting wave energy for the ship in rough seas, the ship's safety can be improved and its energy consumption is reduced. In this paper, the flapping foils are arranged in tandem on both sides of the ship and are subjected to water pressure and shear forces, which passively change the angle of attack and produce force to propel the ship. The foils can be deployed in rough seas to stabilize the ship and retracted in calm water. The ship's motions with foils are modeled and the influence of flapping foils on ship stability is investigated in the frequency domain, which reveals that foils improve ship stability. Numerical studies in STAR-CCM + show that the foils may extract wave energy to propel the ship and generate an anti-pitching moment under different wave encounter angles and different ship speeds.

The Deep Hip Muscles are Unlikely to Stabilize the Hip in the Sagittal Plane During Walking: A Joint Stiffness Approach.

This study determined the contribution of the deep hip muscles to hip stability. Hip stability was defined as rotational hip stiffness in the sagittal plane, which was calculated for walking trials for 12 participants via an electromyography (EMG)-informed neuromusculoskeletal model which included all 22 hip spanning muscles. Three model configurations which differed in deep hip muscle excitations but had identical excitations for all other muscles were compared: (1) deep hip muscles informed by intramuscular EMG measurements (assisted activation); (2) deep hip muscles with simulated zero activation (no activation); (3) deep hip muscles with simulated maximal activation (maximal activation). Sagittal plane rotational hip stiffness across the gait cycle was compared between the three model configurations using a within-participant analysis of variance via statistical parametric mapping (p < 0.05). Compared to the assisted activation configuration, hip stiffness (mean (95% confidence interval)) was 0.8% (0.7 to 0.9) lower in the no activation configuration, and 3.2% (3.0 to 3.4) higher in the maximal activation configuration. Regardless of activation level, deep hip muscles contributed little to sagittal plane rotational hip stiffness, which casts doubt on their assumed function as hip stabilizers. The merit of targeted deep hip muscle strengthening to improve hip stability in rehabilitation programs remains unclear.

Finite Element Analysis and Topology Optimization Design of Anchor Mooring Winch Support Bracket

The weight of the deck machinery greatly affects the position of the small ship’s center of gravity so that it also affects the stability of the ship. Therefore, it is necessary to conduct optimization studies to reduce the weight of ship deck machinery, especially anchor mooring winch, by reducing the weight of ship deck machinery will lower the position of the center of gravity of ship so that can improve ship stability. This paper presents the effects of a topology optimization examination based on the finite element evaluation on anchor mooring winch support bracket using the SolidWorks Simulation module. The main intention to examine is to optimize the general weight of the anchor mooring winch support bracket via way of means of thinning specific regions of the anchor mooring winch support bracket in keeping with the calculated minimum strain energy. The topology optimization algorithm that is used in the current study gives an optimal structural shape of the support bracket of the anchor mooring winch with the largest stiffness, considering the given quantity of mass so that it will be eliminated from the preliminary layout space. The complete sequence of steps for carrying out the topology control optimization study is shown, taking into account the constraints arising from the construction features and the method of manufacturing the support bracket of the anchor mooring winch. The layout became carried out, and the effects have been provided via way of means of evaluating the preliminary version and the optimized version. As the result of topology optimization study, its stress was increased by about 4MPa and mass was reduced by about 15kg in comparison with the initial design.

Inclination, hip abduction, orientation, and tone affect weight-bearing in standing devices.

With children who are unable to stand or walk independently in the community, therapists commonly use standing devices to assist lower-extremity weight-bearing which is important for bone and muscle health. In addition, positioning in hip abduction may improve hip stability and range of motion. This is the first study to explore the effect of angle of inclination, hip abduction, body orientation, and tone on weight-bearing in pediatric standing devices. This descriptive exploratory study used a convenience sample of 15 participants (2 with normal tone, 5 with generalized hypotonia, and 8 with hypertonia) (mean age of 5 years and 10 months, range of 3 years 4 months to 9 years 7 months); 13 of whom used standing devices at home, as well as 2 typically developing siblings (normal tone). Each child stood in 36 positions to measure the amount of weight-bearing through footplates. Weight-bearing was highest with 60 degrees of abduction and no inclination (upright) in supine positioning for children with low and normal tone. Children with high muscle tone bore most weight through their feet with no abduction (feet together) and no inclination (upright) in prone positioning. Overall, supine positioning resulted in more weight-bearing in all positions for children with low and normal tone. Prone positioning resulted in slightly more weight-bearing in all positions for children with high tone. Weight-bearing was affected by all three of the variables (inclination, abduction, and orientation) for participants with high, normal, and low tone. To determine optimal positioning, all standers should include a system to measure where and how much weight-bearing is occurring in the device.

Biomechanical Characteristics of Labral Augmentation Versus Labral Reconstruction in a Hip Cadaver Model

Objectives:An integral component of hip stability is the negative pressure gradient created by the labral suction seal. No prior studies have quantitatively compared the integrity of the suction seal under normal, pathologic, and surgical conditions. The purpose of this study was to evaluate the biomechanical properties of the labral suction seal in the following four scenarios: intact labrum, labral tear, labral augmentation, and labral reconstruction.Methods:Eight fresh-frozen hemi-pelvises without osteoarthritis and with an intact labrum were dissected to the level of labrum and mounted for biomechanical testing. Each specimen was evaluated sequentially under four testing conditions: intact labrum, labral tear, labral augmentation, and labral reconstruction. Following testing of the intact labrum, the specimens were manipulated to create a labral tear from 12- to 3-o’clock. Labral augmentation was then performed with bone anchors and iliotibial band graft after debridement of only the peripheral half of the labral tear. Labral reconstruction was performed last with bone anchors and iliotibial band graft after removing the entire labral tear. In each condition the specimens were placed in the test machine to undergo pure distraction of the joint. First, the femur was compressed with 250 N of force and then distracted at 10 mm/s with force and displacement continuously recorded until the suction seal was disrupted. In each specimen, the tests were repeated for a total of three tests in each of the four conditions, and the average peak force was calculated. Data was normalized to the intact peak force for each specimen to account for gender and size differences. Statistical testing was performed via a repeated measures ANOVA with a post hoc Bonferroni correction for pairwise analysis.Results:Peak loads occurred early in displacement. The average peak force values (mean ± standard deviation) were as follows: intact (137.2 ± 40.7), labral tear (126.3 ± 43.5), labral augmentation (94.7 ± 59.7), labral reconstruction (78.9 ± 51.2). The average normalized peak force values relative to the intact condition were as follows: labral tear (91.1 ± 8.5), augmentation (66.1 ± 27.6), and reconstruction (55.6 ± 25.7). There was no statistically significant difference in peak force relative to the intact labrum for the labral tear (p = 0.34). Relative to the labral tear, there was no significant difference in peak force for the augmentation (p = 0.12), but there was a significant decrease in peak force for the reconstruction (p = 0.03).Conclusion:This model provides a new means of quantitatively evaluating the labral suction seal under various normal, pathologic, and surgical conditions. The results show that relative to the labral tear condition, labral augmentation may recreate the labral suction seal better than labral reconstruction. Clinically, these findings suggest augmentation may improve hip stability over labral reconstruction.Figure 1.

Simultaneous Acetabular Labrum Reconstruction and Remplissage of the Femoral Head–Neck Junction

With the recent increase in the use of hip arthroscopy, revision hip arthroscopy also has become more prevalent; nevertheless, it is often complex, and many factors should be considered to achieve a satisfactory clinical outcome. Labral reconstruction or augmentation technique is used in cases of severely deficient acetabular labral tissue to restore the fluid seal mechanism. In cases of previous over-resection of cam impingement, the remplissage technique, used to restore the bony defect of the femoral head–neck junction and preserve the joint seal, is an established technique that has been recently reported in the hip with the use of iliotibial band with the same aim as in the shoulder, filling in of the defect due to healing of the soft tissue to the underlying bony impression. We aim to describe a labrum reconstruction in combination with a remplissage of the femoral head–neck junction with a dermal graft in a patient with recurrent hip pain after hip scope. This combination may improve hip stability and reduced pain after failed hip scope.

The Development of Monomaran Fishing Boat Hullform to Improve Ship Stability Performance in Supporting the Safety Improvement of Fishing Activity

The Development of Monomaran Fishing Boat Hullform to Improve Ship Stability Performance in Supporting the Safety Improvement of Fishing Activity

Vertical Extension of the T-Capsulotomy Incision in Hip Arthroscopic Surgery Does Not Affect the Force Required for Hip Distraction: Effect of Capsulotomy Size, Type, and Subsequent Repair

Background: Interportal and T-capsulotomies are popular techniques for exposing femoroacetabular impingement deformities. The difference between techniques with regard to the force required to distract the hip is currently unknown. Purpose: To quantify how increasing interportal capsulotomy size, conversion to T-capsulotomy, and subsequent repair affect the force required to distract the hip. Study Design: Controlled laboratory study. Methods: Eight fresh-frozen cadaveric hip specimens were dissected and fixed in a materials testing system, such that pure axial distraction of the iliofemoral ligament could be achieved. The primary outcome measure was the load required to distract the hip to a distance of 6 mm at a rate of 0.5 mm/s. Each hip was tested in the intact state and then sequentially under varying capsulotomy conditions: 2-cm interportal, 4-cm interportal, half-T (4-cm interportal and 2-cm T-capsulotomy), and full-T (4-cm interportal and 4-cm T-capsulotomy). After serial testing, isolated T-limb repair and then subsequent complete repair were performed. Repaired specimens underwent distraction testing as previously stated to assess the ability to restore hip stability to the native profile. Distraction force as well as the relative distraction force (percentage normalized to the intact capsule) were compared between all capsulotomy and repair conditions. Results: Increasing interportal capsulotomy size from 2 to 4 cm resulted in significantly less force required to distract the hip (P < .001). The largest relative decrease in force was seen between the intact state (274.6 ± 71.2 N; 100%) and 2-cm interportal (209.7 ± 73.2 N; 76.4% ± 15.6%; P = .0008). There was no significant mean difference in distraction force when 4-cm interportal (160.4 ± 79.8 N) was converted to half-T (140.7 ± 73.5 N; P = .270) and then full-T (112.0 ± 70.2 N; P = .204). When compared with the intact state, isolated T-limb repair partially restored stability (177.3 ± 86.3 N; 63.5% ± 19.8%; P < .0001), while complete repair exceeded native values (331.7 ± 103.7 N; 122.7% ± 15.1%; P = .0008). Conclusion: The conversion of interportal capsulotomy to T-capsulotomy did not significantly affect the force required to distract the hip in a cadaveric model. However, larger interportal capsulotomies resulted in significant stepwise decreases in distraction force. When performing interportal or T-capsulotomy, the iliofemoral ligament strength is significantly decreased, but complete capsular repair demonstrated the ability to restore joint stability to the native, intact hip. Clinical Relevance: Increasing interportal capsulotomy size decreases the force required to distract the hip. In an effort to maximize visualization and minimize the magnitude of iliofemoral ligament fibers cut, many surgeons have moved from extended interportal capsulotomy to T-capsulotomy. Interportal and T-capsulotomies result in equivalent hip distraction, partial capsular repair marginally improves hip stability, and only complete repair has the ability to restore the hip to its native biomechanical profile.

Application Side Casing on Open Deck RoRo to Improve Ship Stability

RoRo is a vessel that can transport passengers, cargo, container and cars. Open Car Deck is favourite RoRo Vessel in developing countries due to its small GT, small tax and spacious car deck, but it has poor survival of stability. Many accident involve Open Car Deck RoRo which cause fatalities and victim. In order to ensure the safety of the ship, IMO had applied intact stability criteria IS Code 2008 which adapted from Rahola’s Research, but since 2008 IMO improved criteria become probabilistic damage stability SOLAS 2009. The RoRo type Open Car Deck has wide Breadth (B), small Draft (D) and small freeboard. It has difficulties to satisfy the ship’s stability criteria. Side Casings which has been applied in some RoRo have be known reduce freeboard or improve ship’s safety. In this paper investigated the effect side casings to survival of intact dan damage ship’s stability. Calculation has been conducted for four ships without, existing and full side casings. The investigation results shows that defect stability of Open Deck RoRo can be reduce with fitting side casing.

Clinical application of augmented antibiotic-loaded cement spacer in two-stage infected total hip arthroplasty with acetabular bone defect

Objective To investigate the clinical outcomes and complications of augmented antibiotic-loaded cement spacer in two-stage infected total hip arthroplasty with acetabular bone defect. Methods The periprosthetic infection (PJI) patients with acetabular bone defect were retrospectively reviewed from January 2007 to June 2016 in our hospital. A total of 26 patients (11 males and 15 females) were eligibly included in the present study. The mean age was 46.7 years old. The two-stage revision arthroplasty included implants removel, meticulous debridement, implantation of antibiotic-loaded cement spacer in first-stage. After systemic therapy of antibiotics, the prosthesis was implanted in the second-stage. The supra-acetabular antibiotic cement shelf with screws was used to improve hip stability with acetabular wall defect. The handmade acetabular spacer was able to prevent femoral spacer into pelvis in patients with acetabular internal wall defect. The clinical outcomes and complications (spacer dislocation, spacer fracture and acetabular wear) were measured. Results The positive rate of bacteria culture was 80.8% (21/26) and 57.7% (15/26) patients were cultured with staphylococcus. The others were 2 fungus, 2 Gram-positive rod, 1 brucella, 1 pseudomonas aeruginosa, 1 escherichia coli, 1 enterococcus faecalis, 1 defective probiotics, 1 serratiamarcescens and 1 Kocuriaroseus. Moreover, 19.2% (5/26) patients were mixed infection. There was one patient with spacer dislocation and two with spacer fracture. No patients were recurrent infection. Infection was controlled, and two-stage revision was successfully performed in 24 patients. Twenty-two patients were followed averaging 4.1 years (1-8) and the Harris Hip Score was significantly improved from 40.9±14.0 to 81.2±11.2 at the final follow-up (P<0.05). Conclusion The application of augmented antibiotic-loaded cement spacer has satisfactory clinical outcomes in PJI patients with acetabular bone defect. It can provide joint mobility and increase additional joint stability with decreased iatrogenic bone defect caused by acetabular wear. Key words: Arthroplasty, replacement, hip; Prosthesis-related infections; Reoperation; Osteolysis

Total Hip Arthroplasty Patients With Fixed Spinopelvic Alignment Are at Higher Risk of Hip Dislocation

BackgroundSitting radiographs have been used as a pre-operative tool to plan patient-specific total hip arthroplasty (THA) component position that would improve hip stability. Previous work has demonstrated that spinal mobility may impact functional acetabular position when seated. We sought to determine whether patients who dislocate following THA have different sitting spinopelvic alignment or acetabular component orientation compared to patients who did not dislocate. MethodsA consecutive series of 1000 patients underwent post-operative low-dose biplanar spine-to-ankle lateral radiographs in standing and sitting positions 1 year following THA. Twelve patients (1% of all patients) experienced hip dislocation. Patients were categorized as having normal lumbar spines (without radiographic arthrosis) or as having lumbar multi-level degenerative disc disease. Measurements of spinopelvic alignment parameters (including sacral slope, lumbar lordosis, and proximal femur angles) and acetabular component orientation in sitting position (functional inclination and functional anteversion) were performed. ResultsPatients who dislocated had significantly less spine flexion, less change in pelvic tilt, and more hip flexion from standing to sitting positions compared to patients with normal spines. In sitting position, dislocators had acetabular components with less functional inclination and less functional anteversion. ConclusionThis study demonstrates that patients with fixed spinopelvic alignment from standing to sitting position are at higher risk of hip dislocation. Imaging patients from standing to sitting position using this technique can provide valuable information on whether a patient has fixed spinopelvic alignment with postural changes and is therefore at higher risk of dislocation.

Ince-Strutt stability charts for ship parametric roll resonance in irregular waves

Ince-Strutt stability chart of ship parametric roll resonance in irregular waves is conducted and utilized for the exploration of the parametric roll resonance in irregular waves. Ship parametric roll resonance will lead to large amplitude roll motion and even wreck. Firstly, the equation describing the parametric roll resonance in irregular waves is derived according to Grim’s effective theory and the corresponding Ince-Strutt stability charts are obtained. Secondly, the differences of stability charts for the parametric roll resonance in irregular and regular waves are compared. Thirdly, wave phases and peak periods are taken into consideration to obtain a more realistic sea condition. The influence of random wave phases should be taken into consideration when the analyzed points are located near the instability boundary. Stability charts for different wave peak periods are various. Stability charts are helpful for the parameter determination in design stage to better adapt to sailing condition. Last, ship variables are analyzed according to stability charts by a statistical approach. The increase of the metacentric height will help improve ship stability.

Bilateral hip reconstruction improve hip stability, pelvic balance and mobility function in children with cerebral palsy

Bilateral hip reconstruction improve hip stability, pelvic balance and mobility function in children with cerebral palsy

The Use of a Supra-Acetabular Antibiotic-Loaded Cement Shelf to Improve Hip Stability in First-Stage Infected Total Hip Arthroplasty

BackgroundAntibiotic-loaded cement spacers in first-stage revision total hip arthroplasty (THA) for managing infection are associated with high dislocation and fracture rates. The aim of this study was to report the use of an antibiotic-loaded cemented supra-acetabular roof augmentation to reinforce hip stability after cement spacer insertion for first-stage total hip revision in the treatment of infected THA. MethodsWe retrospectively reviewed a consecutive series of 50 THAs involving 47 patients with an infected hip requiring staged revisions of THA. We documented dislocation, reinfection, and time for revision and outcome. ResultsThere were no cases of hip dislocation, cement fractures, or any other technical complications associated with the use of the roof augmentation lip. Thirteen cases (26%) had a cemented spacer for longer than 120 days. Seven (14%) cases had recurrent infection after staged revision THA. ConclusionThe antibiotic-loaded cemented supra-acetabular roof augment improved femoral head spacer coverage for patients requiring a staged revision THA for infection.