Impingement testing of total hip replacements according to ASTM F2582 - Implant wear, resistance to damage and acceptance criteria

OBJECTIVES

The aim of this study was to determine the resistance to impingement damage of three different artificially aged UHMWPE materials used for total hip joint replacement. The results obtained can be used as a basis for an acceptance criterion for testing according to ASTM F2582-20.

METHODS

Three different polyethylene liner materials, standard polyethylene (UHMWPE), moderately crosslinked (XLPE) and vitamin E stabilized crosslinked (XLPE-VE) polyethylene of the same design and manufacturer were tested up to one million impingement cycles according to ASTM F2582-20. The liners were artificially oxygen aged for two and three weeks according to ASTM F2003-02. The wear volumes of the liner, acetabular shells, and hip endoprosthesis stems were determined. Each of the six impingement test groups consisted of three samples. For each test group, a reference group was subjected to the same conditioning and loading conditions but without impingement between the hip stem and the liner. The force needed to disassemble the liner from the acetabular shell (push-out force) was determined according to ASTM F1820-22 for the test and the reference groups.

RESULTS

XLPE and XLPE-VE polyethylene groups showed less impingement wear when compared to the standard UHMWPE material. Similarly, the protective function of the liner against direct metal-on-metal contact was greater, resulting in less wear on the acetabular shell and the stem neck. The three weeks aged standard UHMWPE group showed early onset of fatigue delamination wear. The push-out values remained unchanged for all XLPE liners and the 3-week aged XLPE-VE liners. The aged UHMWPE liners showed low push-out strength due to component shrinkage caused by aging in combination with the tapered fixation used for this specific design.

SIGNIFICANCE

The largest polyethylene wear volume measured of XLPE and XLPE-VE polyethylene aged for two and three weeks was 15.05 mm³ (SD 0.56 mm³). The corresponding metal wear volume was 1.23 mm³ (SD 0.19 mm³) for the acetabular cup and 1.33 mm³ (SD 0.20 mm³) for the stem neck. Those values can support the definition of an acceptance criteria for impingement testing. The results of the push-out test required by ASTM F2582-20 should be evaluated with respect to geometry changes caused by aging. The protective effect of the polyethylene liner against metal-on-metal contact should be considered in the implant design phase in order to avoid implant failure due to metal debris.

Combining Poly-(ARD-Ribose) Polymerase and Programmed Cell Death Protein 1 Inhibition in a Patient with Esophagogastric Adenocarcinoma

INTRODUCTION

Esophagogastric adenocarcinoma (EGA) is one of the leading causes of cancer-related mortality worldwide. Therapeutic options are limited for patients with recurrent or metastatic disease. Targeted therapy may be a suitable treatment for selected patients, but its efficacy remains elusive.

CASE PRESENTATION

Here, a 52-year-old male patient with advanced EGA Siewert Type II shows a significant response to combination therapy with olaparib and pembrolizumab. After progression following first- and second-line therapy, including a programmed cell death ligand 1 (PD-L1) inhibitor, next-generation sequencing of a tumor sample was performed to identify possible molecular targets. A mutation in RAD51C, a member of the homology-directed repair (HDR) system, was identified in addition to high PD-L1 expression. As a result, therapy with the poly-(ARD-Ribose) polymerase (PARP) inhibitor olaparib and the programmed cell death protein 1 (PD1)-inhibitor pembrolizumab was initiated. A durable partial response lasting for more than 17 months was observed. A second molecular profiling from a newly occurring subcutaneous metastasis showed a loss of FGF10 but no fluctuations in the gene alteration of RAD51C and SMARCA4. Interestingly, the new lesion showed HER2-positivity (immunohistochemistry 3+ and fluorescence in situ hybridization [FISH]-positivity) in 30% of tumor cells.

CONCLUSION

In this case, a long-lasting response to the combination of olaparib and pembrolizumab was observed despite previous treatment with a PD-L1 inhibitor. This case illustrates the need for further clinical trials to analyze the efficacy of PARP inhibitor combinations in EGA.

[Penile paraffinoma-Treatment strategies]

BACKGROUND

Penile paraffinomas are a consequence of an injection of mineral oils for augmentation. As an result of the foreign body reaction local complications regularly occur, which require a plastic reconstructive intervention. So far 8 cases have been treated in our clinic over the last 20 years.

OBJECTIVE

Presentation of the operative treatment techniques for penile paraffinoma as well as the indications and complications.

MATERIAL AND METHODS

After reviewing the relevant literature, we analyzed the data of our own patient cohort. Since 1999 a total of 8 patients with lipogranuloma underwent surgical treatment at the St. Antonius Hospital in Eschweiler.

RESULTS

The choice of a plastic reconstructive treatment depends on the extent of the paraffinoma. If it is limited to the foreskin, a radical circumcision is sufficient but if it extends to the skin of the penile shaft, a plastic defect coverage with a mesh graft, a full skin graft or a scrotal skin flap is required. In cases with additional pathologies, such as urethral fistulas, auxiliary reconstructive procedures should be performed.

CONCLUSION

For optimal cosmetic and functional results, the surgeon must master a broad spectrum of plastic reconstructive techniques. In selected complex cases an interdisciplinary approach consisting of urologists and plastic surgeons can be necessary.

[Vascular injuries during urologic surgery]

This review article summarizes the epidemiology of vascular injuries during urologic surgery and discusses intraoperative strategies to control bleedings. Techniques of vascular approaches (arteries and veins) are discussed and tricks for vascular repair are explained. Generally, vascular injuries during urologic surgery are rare. However, hemorrhage due to vascular injury is a common cause of critical morbidity and mortality in the perioperative period. Susceptibility to vascular complications such as oncological debulking and revision surgery increase risk for damage. As vascular injuries range from arrosion to avulsion, treatment is also broad, ranging from vascular suture to open or endovascular repair. Prevention of exsanguination requires visual control to stop the bleeding. The surgeon must act quickly to initiate appropriate repair, aiming for damage control and stabilization of the patient. Planning the surgery and consulting an experienced surgeon are decisive for successful management. Catastrophic bleeding has to be controlled and in the case of arterial injury it is often necessary to reconstitute perfusion. Reconstructions such as vascular anastomoses, patch angioplasty or interposition grafts are the preferred surgical techniques which are influenced by the nature of the injury. Vessels have to be thoroughly prepared before cross clamping to prevent injury by vascular clamps. Veins can often be ligated. Endovascular repair is also a possibility to control the bleeding, but nowadays it is often a definitive therapy method. For example, resuscitative endovascular balloon occlusion is useful to stabilize the patient and then to initiate vascular repair. Depending on the type of surgery performed, different vessels are concerned. Severe bleeding is usually located retroperitoneal affecting the aorta, renovisceral and iliac vessels. Predisposing urologic operations are lymphadenectomy, nephrectomy and (cysto)prostatectomy and also the laparoscopic approach can cause bleeding complications.

Vesico-urethral anastomotic stenosis following radical prostatectomy: a multi-institutional outcome analysis with a focus on endoscopic approach, surgical sequence, and the impact of radiation therapy

OBJECTIVES

To investigate the predictors of recurrence and of de novo incontinence in patients treated by transurethral incision or resection for vesico-urethral anastomotic stenosis (VUAS) after radical prostatectomy.

MATERIAL AND METHODS

All patients undergoing endoscopic treatment for VUAS between March 2009 and October 2016 were identified in our multi-institutional database. Digital chart reviews were performed and patients contacted for follow-up. Recurrence was defined as any need for further instrumentation or surgery, and de-novo-incontinence as patient-reported outcome.

RESULTS

Of 103 patients undergoing endoscopic VUAS treatment, 67 (65%) underwent transurethral resection (TR) and 36 (35%) transurethral incision (TI). TI was performed more frequently as primary treatment compared to TR (58% vs. 37%; p = 0.041). Primary and repeated treatment was performed in 46 (45%) and 57 patients (55%), respectively. Overall, 38 patients (37%) had a history of radiation therapy. There was no difference in time to recurrence for primary vs repeat VUAS treatment, previous vs no radiation, TR compared to TI (all p > 0.08). Regarding treatment success, no difference was found for primary vs. repeat VUAS treatment (50% vs. 37%), previous radiation vs. no radiation (42% vs. 43%), and TR vs. TI (37% vs. 53%; all p ≥ 0.1). Postoperative de novo incontinence was more common after TI vs. TR (31% vs. 12%; p = 0.032), no difference was observed for previous radiation therapy vs. no radiation therapy (18% vs. 18%; p > 0.9) or primary vs. repeat VUAS treatment (22% vs. 16%; p = 0.5).

CONCLUSION

VUAS recurrence after endoscopic treatment is not predictable. Endoscopic treatment with TI showed a higher risk for de novo incontinence than TR, and previous irradiation and the number of treatments do not influence incontinence.

[Knowledge and early detection of testicular germ cell cancer among adolescents and young adults]

INTRODUCTION

Malignant testicular germ cell tumors are the most common tumor disease in young men, affecting not only the period of his reproductive phase but also creating a complex life situation. Therapy includes the risk of development of second neoplasia and sequelae. However, particularly in this age group, knowledge about this disease and risk factors is sparse, and preventive examinations are not available or are not or insufficiently used.

MATERIALS AND METHODS

In order to evaluate the state of knowledge on testicular tumors in adolescents, a knowledge survey was conducted at 6 high schools in Hamburg from January to April 2019 among pupils of grades 11 and 12. This was carried out with a questionnaire comprising 15 items, which was analyzed and also evaluated on a gender-specific basis. Only fully completed questionnaires were considered.

RESULTS

The overall proportion of correctly answered questions was 60.04%. Broken down by gender, the proportion was 60.18% for female pupils and 59.14% for male pupils, while the gender ratio was 52.2 and 47.8% for female pupils. Special questions on testicular tumors were answered correctly by 59.71% of the female students and 54.8% of the male students, while general questions on the structure and function of the male sexual organs were answered 4.51% better by the male students with 64.9%. These were statistically significant in both cases.

CONCLUSION

The survey shows a gender-specific knowledge deficit on testicular tumors, which is more pronounced among boys. As intensified knowledge transfer on this topic alone is insufficient, a preventive examination should be established especially for boys. This would enable individual, risk-commensurate and needs-adapted monitoring and early detection of testicular tumor disease, but also of other health issues in male adolescents.

[Patio repair for urethrocutaneous fistulae : Results of a multicentre retrospective study]

BACKGROUND

Urethrocutaneous (UC) fistulae are common complications after hypospadias surgery and they have been a serious problem for surgeons since the repair was first attempted. We present the results of our multicentre retrospective study for repairing UC fistulae using the Patio ("preserve the tract and turn it inside out") repair described by Malone.

MATERIALS AND METHODS

A total of 16 boys (Eschweiler 2, Lingen 4, Reading 10) at the ages of 1-10 years were treated for UC fistulae. Instead of excising the fistula tract, it is preserved and turned inside out, this creates a flap valve inside the urethral lumen. After a circumferential incision around the skin and meticulous dissection of the fistula tract, a 2/0 nylon suture is passed down the tract and brought out through the external urinary meatus. As a result, the fistula tract is inserted into the urethral lumen. In order to keep the fistula tract inverted, it is sutured to the tip of the external urinary meatus, or fixed by an angler lead (modification from Lingen). Due to the narrow base, the excess tissue atrophies postoperatively and leads to an appealing cosmetic result.

RESULTS

A total of 9 fistula repairs were performed on an outpatient basis without using a transurethral catheter; 7 boys were treated on an inpatient basis with an average length of stay in the hospital for 1-2 days with/without catheterization. During a mean follow-up of up to 4.5 years, only one fistula recurrence occurred; no other complications were observed.

CONCLUSION

The Patio repair for urethrocutaneous fistula is an outpatient, simply reproducible surgical technique without the necessity of transurethral catheterization. The short-term results are impressive; long-term results of a larger patient cohort will follow.

[Ureteral stricture as a late complication of radiotherapy : Possible treatment options]

Ureteral strictures are uncommon complications of radiotherapy which are often recognized late. Their consequences range from harmless dilatation of the ureter to loss of renal function and potential life-threatening urosepsis.Therapy of radiogenic ureteral stricture is a challenging task for every urologist. Several surgical strategies including minimally invasive procedures, reconstruction and partial or complete replacement of the ureter are available.This article provides an overview of the various options in the treatment of radiogenic stricture of the ureter, focusing on the use of ileum and colon segments for ureteral substitution.

[General and method-specific complications of sacrocolpopexy]

Sacrocolpopexy has remained standard procedure for correction of pelvic organ prolapse regardless of the affected compartment. Assuming the appropriate indication, it is characterized by an excellent long-term cure rate. Asymptomatic pelvic organ prolapse is no indication for surgery and should not be corrected in view of possible complications. This article summarizes general and method-specific complications of sacrocolpopexy, identifies causes, and allows error management to be tailored to each individual patient to increase treatment and outcome quality.

[Process design in high-reliability organizations]

Modern medicine is a highly complex service industry in which individual care providers are linked in a complicated network. The complexity and interlinkedness is associated with risks concerning patient safety. Other highly complex industries like commercial aviation have succeeded in maintaining or even increasing its safety levels despite rapidly increasing passenger figures. Standard operating procedures (SOPs), crew resource management (CRM), as well as operational risk evaluation (ORE) are historically developed and trusted parts of a comprehensive and systemic safety program. If medicine wants to follow this quantum leap towards increased patient safety, it must intensively evaluate the results of other high-reliability industries and seek step-by-step implementation after a critical assessment.

[Error prevention through management of complications in urology: standard operating procedures from commercial aviation as a model]

Patient safety and risk/complication management rank among the current megatrends in modern medicine, which has undoubtedly become more complex. In time-critical, error-prone and difficult situations, which often occur repeatedly in everyday clinical practice, guidelines are inappropriate for acting rapidly and intelligently. With the establishment and consistent use of standard operating procedures like in commercial aviation, a possible strategic approach is available. These medical aids to decision-making - quick reference cards - are short, optimized instructions that enable a standardized procedure in case of medical claims.

Design of Cherenkov bars for the optical part of the time-of-flight detector in Geant4

We present the results of studies devoted to the development and optimization of the optical part of a high precision time-of-flight (TOF) detector for the Large Hadron Collider (LHC). This work was motivated by a proposal to use such a detector in conjunction with a silicon detector to tag and measure protons from interactions of the type p + p → p + X + p, where the two outgoing protons are scattered in the very forward directions. The fast timing detector uses fused silica (quartz) bars that emit Cherenkov radiation as a relativistic particle passes through and the emitted Cherenkov photons are detected by, for instance, a micro-channel plate multi-anode Photomultiplier Tube (MCP-PMT). Several possible designs are implemented in Geant4 and studied for timing optimization as a function of the arrival time, and the number of Cherenkov photons reaching the photo-sensor.

[Radical prostatectomy in a certified prostate cancer center: medical treatment and outcome]

INTRODUCTION

Open radical prostatectomy (RPE) is a standardized surgical technique with good oncologic/functional results. Nevertheless, the postoperative quality of life can be affected significantly by urinary incontinence and erectile dysfunction. Consequently, data of postoperative health-related quality of life come increasingly into public interest.

MATERIALS AND METHODS

This paper aims to evaluate the quality of care after radical RPE at a certified prostate cancer center. The oncological outcome, rate of complications, reintervention and transfusions as well as the rate of continence and potency of a total collective of nearly 400 patients was obtained in a standardized manner between January 2008 and June 2012 using the clinic's internal tumor documentation system and commonly used, validated questionnaires. Due to consistent methodology, partial results can finally be compared with data prior to establishment of the prostate cancer center.

RESULTS

This study is the first German report demonstrating an improvement of treatment results in a certified prostate cancer center. The rate of complications, reintervention, transfusions, and R1 status were significantly lower than in the precenter era. The evaluation of potency is sobering compared to current published literature, whereas satisfactory results were obtained for continency.

DISCUSSION

Evaluation of the data contributes to the quality of treatment and outcome of certified prostate cancer centers and allows reliable decision-making and honest patient education in the future.

[New patients' rights act--what do we have to consider?]

The controversially discussed act of improving the rights of patients entered into force in Germany on 26 February 2013 without any transitional period. The current law of patients "rights brings together patients" rights at one uniform place in the civil code (BGB, "Bürgerlichen Gesetzbuch") and should, therefore, attract the medical stakeholders' interest. The new patients "rights law improves the patients" position concerning both treatment and doctor's liability law and is supposed to strengthen a new "error culture" in health care. Similarly, clinical and daily practice becomes more complex with high levels of bureaucracy and the patient-physician relation shifts in favour of meticulous documentation.

[Primary megaureter]

A primary megaureter is an anomaly with a prevesical or overall dilated ureter of more than 6 mm in diameter. It is important to distinguish between cases of primary non-refluxing and primary obstructive-refluxing megaureters, as the treatment of both is completely different. The basic diagnostic work-up includes ultrasonography and voiding cystourethrography. Diuretic renography is used to detect split renal function and the degree of upper urinary tract obstruction. In most cases of primary non-refluxing megaureter surgical treatment is unnecessary due to the high remission rate, whereas obstructive refluxing megaureters commonly only need to be corrected. Antibiotic prophylaxis may be indicated in infants with a primary obstructive megaureter during the first 6 months of life due to a higher risk of complications due to pyelonephritis especially in this age group.

[Treatment of urethral meatus stenosis due to Balanitis xerotic obliterans. Long term results using the meatoplasty of Malone]

OBJECTIVE

To present our experience in the treatment of severe stenosis of the external urinary meatus in male children and adults with balanitis xerotic obliterans.

MATERIALS AND METHODS

A total of 21 patients were operated on in a 5-year period, using the meatoplasty technique of Malone. Mean patient age was 41.7 years (range 7-75). Mean postoperative follow-up was 40.8 months (range 6-54). The surgical procedure consisted in making a small ventral incision of the urethral meatus with an extensive dorsal meatotomy, correcting the esthetic defect of the gland with an inverted V-shaped relieving incision. The postoperative evaluation was performed in every patient by written questionnaire informing about the functional and cosmetic results of the surgical technique.

RESULTS

No post-surgical complications or recurrences of the urethral stenosis were recorded. A total of 18 patients (85.7%) replied to the post-surgical questionnaire. All were very satisfied with the functional result. Fifteen (83.3%) were also very satisfied with the cosmetic results of the technique.

CONCLUSION

The meatoplasty of Malone is a good alternative for the treatment of urethral meatal stenosis. It is an easy and rapid-to-perform technique. It avoids creating a hypospadiac meatus and achieves good postoperative results.

Propofol, remifentanil and mivacurium: fast track surgery with poor intubating conditions

BACKGROUND

Mivacurium is widespread used because it is the non-depolarizing muscle relaxant with the shortest duration time. Therefore, it seems to be ideal for fast track or ambulatory surgery. However, especially in combination with propofol and remifentanil onset time remains unclear and incidence of poor intubating conditions seems to be higher than in other regimes of anesthesia.

METHODS

We included 35 ear, nose and throat (ENT) patients in this study. Muscle relaxation was measured by acceleromyograhpy at the adductor pollicis muscle (a.p.m.) and intubating conditions were evaluated. Anesthesia was induced with 2.5 mg kg-1 propofol and 1 µg kg-1 remifentanil and intubation was performed three minutes after the administration of 0.2 mg kg-1 mivacurium. Open vocal cords conjoined with full relaxation of the a.p.m., easy mouth opening and prevention of coughing and bucking represented the primary endpoint in this study.

RESULTS

Only 20% of patients (N.=7) had optimal intubating conditions and achieved the primary endpoint. In 21 patients (60%) a complete block of the a.p.m. could not be achieved and in six patients (17%) the vocal cords were closed. In seven patients (20%) we observed difficult mouth opening and in 11 patients (31%) coughing and bucking. In addition, we found a prolonged onset time of 228±95 seconds (mean±SD).

CONCLUSION

In combination with propofol and remifentanil the muscle relaxant agent mivacurium led to uncertain muscle relaxation and to poor intubating conditions. Therefore the study was aborted after 35 patients. Probably mivacurium is not a useful muscle relaxant agent if fast and deep muscle relaxation is needed. The advantage of a short duration time is foiled by intubation complications due to insufficient muscle relaxation.

[Treatment of vesicoureteral reflux in childhood]

The pathophysiology, evaluation and therapy of vesicoureteral reflux (VUR) were newly illuminated over the past years through different clinical studies and basic research. Our understanding of vesicoureteral reflux and the therapeutic spectrum of its treatment should therefore consistently undergo critical revision. The Swedish Reflux Study set up three different therapy options for small children with dilated VUR: antibiotic prophylaxis, endoscopic reflux correction and surveillance were prospectively analysed in a randomized fashion. The results are discussed in this work and completed with a statement about open operative reflux therapy.

[Management of pediatric testicular tumors : diagnosis, therapy, and follow-up]

Based on findings from the Prepubertal Testis Tumor Registry by the Urologic Section of the American Academy of Pediatrics and collaborative data in the literature, a modern algorithm for the surgical management of prepubertal testis tumors is presented. Following testicular surgery, patients with universally benign tumors, such as teratoma, may be released from oncological follow-up. Children with stage I yolk sac tumors should be monitored closely with periodic AFP tumor marker evaluation and imaging according to the primary dissemination (e.g., ultrasound, chest x-ray, and computed tomography). Patients with recurrent or metastatic yolk sac tumors should be treated with platinum-based chemotherapy and appropriate follow-up. Retroperitoneal lymph node dissection is not recommended except for patients with residual retroperitoneal masses following chemotherapy. Aggressive treatment is warranted for metastatic Sertoli cell and metastatic undifferentiated stromal tumors.

Progressive multifocal leucoencephalopathy associated with lupus and methotrexate overdose

Progressive multifocal leucoencephalopathy (PML) is a CNS infection of oligodendrocytes by JC virus, which rarely occurs in lupus, and can be mistaken for antiphospholipid antibody syndrome or neuropsychiatric systemic lupus erythematosus (NSLE). This case of PML in a patient with systemic lupus erythematosus on supra-therapeutic doses of methotrexate emphasises that CNS infection is an important diagnostic consideration before empiric treatment with immunosuppresants for NSLE.