ABSTRACT
PURPOSE: Iatrogenic ureteral strictures (US) after endoscopic treatment for urolithiasis represent a significant healthcare concern. However, high-quality evidence on the risk factors associated with US is currently lacking. We aimed to develop a consensus statement addressing the definition, risk factors, and follow-up management of iatrogenic US after endoscopic treatment for urolithiasis. METHODS: Utilizing a modified Delphi method, a steering committee developed survey statements based on a systematic literature review. Then, a two-round online survey was submitted to 25 experts, offering voting options to assess agreement levels. A consensus panel meeting was held for unresolved statements. The predetermined consensus threshold was set at 70%. RESULTS: The steering committee formulated 73 statements. In the initial survey, consensus was reached on 56 (77%) statements. Following in-depth discussions and refinement of 17 (23%) statements in a consensus meeting, the second survey achieved consensus on 63 (86%) statements. This process underscored agreement on pivotal factors influencing US in endoscopic urolithiasis treatments. CONCLUSIONS: This study provides a comprehensive list of categorized risk factors for US following endoscopic urolithiasis treatments. The objectives include enhancing uniformity in research, minimizing redundancy in outcome assessments, and effectively addressing risk factors associated with US. These findings are crucial for designing future clinical trials and guiding endoscopic surgeons in mitigating the risk of US.
Subject(s)
Delphi Technique , Ureteral Obstruction , Ureteroscopy , Urolithiasis , Humans , Urolithiasis/surgery , Risk Factors , Ureteroscopy/adverse effects , Ureteral Obstruction/surgery , Ureteral Obstruction/etiology , Constriction, Pathologic , Postoperative Complications/etiology , Iatrogenic Disease , Internationality , ConsensusABSTRACT
PURPOSE: We aimed to accurately determine ureteral stricture (US) rates following urolithiasis treatments and their related risk factors. METHODS: We conducted a systematic review and meta-analysis following the PRISMA guidelines using databases from inception to November 2023. Studies were deemed eligible for analysis if they included ≥ 18 years old patients with urinary lithiasis (Patients) who were subjected to endoscopic treatment (Intervention) with ureteroscopy (URS), percutaneous nephrolithotomy (PCNL), or shock wave lithotripsy (SWL) (Comparator) to assess the incidence of US (Outcome) in prospective and retrospective studies (Study design). RESULTS: A total of 43 studies were included. The pooled US rate was 1.3% post-SWL and 2.1% post-PCNL. The pooled rate of US post-URS was 1.9% but raised to 2.7% considering the last five years' studies and 4.9% if the stone was impacted. Moreover, the pooled US rate differed if follow-ups were under or over six months. Patients with proximal ureteral stone, preoperative hydronephrosis, intraoperative ureteral perforation, and impacted stones showed higher US risk post-endoscopic intervention with odds ratio of 1.6 (P = 0.05), 2.6 (P = 0.009), 7.1 (P < 0.001), and 7.47 (P = 0.003), respectively. CONCLUSIONS: The overall US rate ranges from 0.3 to 4.9%, with an increasing trend in the last few years. It is influenced by type of treatment, stone location and impaction, preoperative hydronephrosis and intraoperative perforation. Future standardized reporting and prospective and more extended follow-up studies might contribute to a better understanding of US risks related to calculi treatment.
Subject(s)
Lithotripsy , Postoperative Complications , Ureteroscopy , Urolithiasis , Humans , Ureteroscopy/adverse effects , Risk Factors , Urolithiasis/surgery , Urolithiasis/epidemiology , Postoperative Complications/epidemiology , Postoperative Complications/etiology , Lithotripsy/adverse effects , Lithotripsy/methods , Constriction, Pathologic , Nephrolithotomy, Percutaneous/adverse effects , Nephrolithotomy, Percutaneous/methods , Ureteral Obstruction/etiology , Ureteral Obstruction/surgeryABSTRACT
To compare the diagnostic performance of 68Ga-PSMA PET/TC with PRI-MUS (prostate risk identification using micro-ultrasound) in the primary diagnosis of prostate cancer (PCa). Methods From September till December 2018, we prospectively enrolled 25 candidates to 68Ga-PSMA PET/TRUS (transrectal ultrasound) fusion biopsy and compared them with PRI-MUS. This included patients with persistently elevated PSA and/or PHI (prostate health index) suspicious for PCa, negative digital rectal examination, with either negative or contraindication to mpMRI, and at least one negative biopsy. The diagnostic performance of the two modalities was calculated based on pathology results. Results Overall, 20 patients were addressed to 68Ga-PSMA PET/TRUS fusion biopsy. Mean SUVmax and SUVratio for PCa lesions resulted significantly higher than in benign lesions (p = 0.041 and 0.011, respectively). Using optimal cut-off points, 68Ga-PSMA PET/CT demonstrated an overall accuracy of 83% for SUVmax ≥ 5.4 and 94% for SUVratio ≥ 2.2 in the detection of clinically significant PCa (GS ≥ 7). On counterpart, PRI-MUS results were: score 3 in nine patients (45%), score 4 in ten patients (50%), and one patient with score 5. PRI-MUS score 4 and 5 demonstrated an overall accuracy of 61% in detecting clinically significant PCa. Conclusion In this highly-selected patient population, in comparison to PRI-MUS, 68Ga-PSMA PET/CT shows a higher diagnostic performance (AU)
Subject(s)
Humans , Male , Middle Aged , Aged , Aged, 80 and over , Gallium Isotopes/administration & dosage , Gallium Radioisotopes/administration & dosage , Positron-Emission Tomography/methods , Prostatic Neoplasms/diagnostic imaging , Prostatic Neoplasms/pathology , Ultrasonography/methods , Prospective Studies , Image-Guided Biopsy/methods , Prostate-Specific Antigen/blood , RadiopharmaceuticalsABSTRACT
PURPOSE: To compare the diagnostic performance of 68Ga-PSMA PET/TC with PRI-MUS (prostate risk identification using micro-ultrasound) in the primary diagnosis of prostate cancer (PCa). METHODS: From September till December 2018, we prospectively enrolled 25 candidates to 68Ga-PSMA PET/TRUS (transrectal ultrasound) fusion biopsy and compared them with PRI-MUS. This included patients with persistently elevated PSA and/or PHI (prostate health index) suspicious for PCa, negative digital rectal examination, with either negative or contraindication to mpMRI, and at least one negative biopsy. The diagnostic performance of the two modalities was calculated based on pathology results. RESULTS: Overall, 20 patients were addressed to 68Ga-PSMA PET/TRUS fusion biopsy. Mean SUVmax and SUVratio for PCa lesions resulted significantly higher than in benign lesions (p = 0.041 and 0.011, respectively). Using optimal cut-off points, 68Ga-PSMA PET/CT demonstrated an overall accuracy of 83% for SUVmax ≥ 5.4 and 94% for SUVratio ≥ 2.2 in the detection of clinically significant PCa (GS ≥ 7). On counterpart, PRI-MUS results were: score 3 in nine patients (45%), score 4 in ten patients (50%), and one patient with score 5. PRI-MUS score 4 and 5 demonstrated an overall accuracy of 61% in detecting clinically significant PCa. CONCLUSION: In this highly-selected patient population, in comparison to PRI-MUS, 68Ga-PSMA PET/CT shows a higher diagnostic performance.
Subject(s)
Gallium Isotopes , Gallium Radioisotopes , Positron Emission Tomography Computed Tomography/methods , Prostatic Neoplasms/diagnostic imaging , Radiopharmaceuticals , Ultrasonography/methods , Aged , Aged, 80 and over , Humans , Image-Guided Biopsy/methods , Male , Middle Aged , Prospective Studies , Prostate-Specific Antigen/blood , Prostatic Neoplasms/blood , Prostatic Neoplasms/pathologyABSTRACT
Kidney stones are a common disorder of the urinary tract. Nephrolithiasis is a morbid and expensive disease. The prevalence and incidence are estimated at 5-10% and 100-300/100,000/year, respectively. Relapses occur in 50-70% of all cases. For these reasons, prevention of stone formation is of great importance. Knowing the composition of the calculus is thus fundamental for a more complete evaluation of the metabolic study. The nature of the calculus in fact helps the physician to find a convenient metaphylaxis consisting of both sanitary and therapeutic measures. Study of the composition of urinary stones remains one of the most interesting aspects of the lithiasic pathology today. Presently crystallographic examination constitutes one of the most precise and less expensive methodologies to identify the nature of the concretion. This method also allows the urologist to catalogue the typology of the lithiasis during endoscopy.
Subject(s)
Kidney Calculi/chemistry , Nephrolithiasis/metabolism , Calcium Oxalate/analysis , Calcium Phosphates/analysis , Crystallography , Humans , Magnesium Compounds/analysis , Phosphates/analysis , Struvite , Uric Acid/analysisABSTRACT
AIM: We report our experience about bipolar plasma-kinetic resection of the prostate for the treatment of bladder outlet obstruction due to benign prostatic hyperplasia (BPH), considering intraoperative variables and short-term METHODS: Three hundred and eighty-nine patients affected by symptomatic BPH, underwent transurethral resection of prostate using the bipolar plasma-kinetic technique from Decem-ber 2001 to July 2004 in a prospective fashion. Bipolar resections of the prostate were performed using Plasma-Kinetic Tissue Management System (Gyrus Medical Ltd., UK). Preoperative, digital rectal examination, haemoglobin level, total PSA, transrectal ultrasound, International-Prostate Symptom Score (I-PSS) and uroflowmetry parameters were recorded. Patients were assessed for safety and efficacy, evaluating intraoperative and postoperative complications and measuring both the IPSS and the maximum flow rates (Qmax) after 12 months. RESULTS: The mean operative time was 89 min (range 48-121 min); the mean prostatic resected weight (measured by an electronic scales) was 49.6 g (3267 g). The mean decrease of haemoglobin level was 1.1 g/dL (range 0.5-1.9), with a mean catheterization time of 1.3 days (range 1-5). Qmax increase ranged from 120 to 230% (mean 190%) 12 months after surgery. Correspondingly, IPSS decrease ranged from 48% to 86% (mean 79%). Postoperative acute urinary retention, urethral strictures, bladder neck sclerosis and urinary incontinence were recorded in 1.57%, 2.57%, 1.28% and 0.77%, respective. CONCLUSION: The transurethral resection of prostate using a bipolar plasma-kinetic device represent a safe and effective option for the treatment of symptomatic BPH.
Subject(s)
Prostatic Hyperplasia/complications , Prostatic Hyperplasia/surgery , Transurethral Resection of Prostate/instrumentation , Urinary Bladder Neck Obstruction/etiology , Aged , Aged, 80 and over , Equipment Design , Humans , Italy , Male , Middle Aged , Prospective Studies , Prostatic Hyperplasia/diagnosis , Sicily , Transurethral Resection of Prostate/adverse effects , Transurethral Resection of Prostate/methods , Treatment Outcome , Urethral Stricture/etiology , Urinary Incontinence/etiology , Urinary Retention/etiologyABSTRACT
OBJECTIVE: To establish the incidence of prostate cancer (PCa) in Sicily in patients who entered an early detection protocol. METHODS: From February 2002 to February 2004, 16,298 subjects aged 40-75 entered the protocol. Patients with suspicious DRE, PSA>10 ng/ml, PSASubject(s)
Prostatic Neoplasms/epidemiology
, Adult
, Age Distribution
, Aged
, Biopsy, Needle
, Humans
, Incidence
, Male
, Middle Aged
, Odds Ratio
, Palpation/methods
, Prevalence
, Prostate/diagnostic imaging
, Prostate/pathology
, Prostate-Specific Antigen/blood
, Prostatic Neoplasms/blood
, Prostatic Neoplasms/diagnosis
, Retrospective Studies
, Risk Factors
, Sicily/epidemiology
, Ultrasonography
ABSTRACT
OBJECTIVES: We evaluated the effect of nifedipine associated with prednisolone in ureteral stone passage. MATERIAL AND METHODS: In our department we enrolled 50 patients with radiopaque ureteral stones. Stone size was 15 mm or less. The patients were divided into two groups: group I included 25 patients who received 30 mg oral treatment of slow-release nifedipine (for a maximum of 20 days) and 25 mg of prednisolone (for a maximum of 10 days) daily. Group II was made up of 25 patients who received 25 mg of prednisolone daily. On request, both groups could use non-steroidal anti-inflammatory drugs. RESULTS: The mean expulsion time was 6 days in group I and 10 days in group II. The average stone size was 12 mm in group I and 12.8 mm in group II. Six patients suspended therapy in group I (5 erythema, 1 stomachache), and seven in group II (3 because of intolerable pain, 4 stomachache). The expulsion success rates were 68% in group I and 81% in group II. CONCLUSIONS: For ureteral stones that do not cause an emergency situation, such as obstructive uropathy, infection or intolerable pain, we suggest expulsive medical treatment with nifedipine and prednisolone, if there are no contraindications to drug use.
Subject(s)
Nifedipine/administration & dosage , Prednisolone/administration & dosage , Ureteral Calculi/drug therapy , Administration, Oral , Delayed-Action Preparations/administration & dosage , Dose-Response Relationship, Drug , Drug Administration Schedule , Drug Therapy, Combination , Female , Follow-Up Studies , Humans , Male , Prospective Studies , Radiography , Risk Assessment , Severity of Illness Index , Treatment Outcome , Ureteral Calculi/diagnostic imagingABSTRACT
OBJECTIVE: We compared the effects of intramuscular analgesia versus intramuscular analgesia associated with topical application of Luan (gel containing lidocaine 1%) on the efficacy of extracorporeal shockwave lithotripsy (ESWL). MATERIAL AND METHODS: From January 2001 to November 2002, 300 patients (mean age 46) were treated for kidney or upper ureteral radiopaque stones with ESWL, using a Dornier Compact Delta magneto lithotripter. The patients were divided into two groups: group A, 180 patients, received intramuscular analgesia with Ketorolac 30 mg, Tramadolo 100 mg and, during treatment, intravenous betametasone 4 mg. Group B, 120 patients, received the same pharmacological treatment associated with topical application of Luan. RESULTS: At 3 months, the stone-free rate in group A was 61% compared with 79% in group B. The energy of treatment was less than 13 kV in group A and less than 15 kV in group B. CONCLUSIONS: For ESWL treatment of kidney stones of 20 mm or less and ureteral stones of 15 mm or less, we suggest local analgesia with topical Luan and intramuscular analgesia. This approach increases the success rate of ESWL and reduces the discomfort associated with treatment.
Subject(s)
Ketorolac Tromethamine/administration & dosage , Ketorolac/administration & dosage , Lidocaine/administration & dosage , Lithotripsy/methods , Prilocaine/administration & dosage , Administration, Topical , Adult , Aged , Analgesia/methods , Betamethasone/administration & dosage , Drug Therapy, Combination , Female , Humans , Injections, Intramuscular , Kidney Calculi/diagnostic imaging , Kidney Calculi/therapy , Male , Middle Aged , Pain Measurement , Prospective Studies , Radiography , Treatment Outcome , Ureteral Calculi/diagnostic imaging , Ureteral Calculi/therapyABSTRACT
Ca 15-3 is an aspecific tumor marker characteristic of cancer proliferation. Elevated serum levels seem to be closely correlated with cancer progression in non-urological tumors. This study assessed the role of Ca 15-3 as an aspecific tumor marker in patients with borderline prostate-specific antigen (PSA) biochemically suspected of prostate cancer (PCa) and with multiple negative prostate biopsies. The study is based on prospective analysis of 103 patients: (a) 33 patients (group A) presented lower urinary tract symptoms secondary to BPH with normal serum PSA values, DRE and TRUS negative for suspected PCa; (b) 31 patients (group B) with histologically diagnosed PCa; (c) 39 patients (group C) with borderline serum PSA values, DRE and TRUS normal, two ultrasound (US)-guided random prostate biopsies negative for PCa. Ca 15-3 was determined in the entire study series by the IRMA method, using as range the values proposed for the investigated non-urological tumors (38 UI/l).Ca 15-3 was within normal range in all group A patients (control), while the values were elevated in 27/31 of group B patients (PCa) and in 11/39 of group C (PCa suspected) patients. A third biopsy was performed in all 39 group C patients with borderline PSA and it was PCa-positive in 13 patients (33.3%, subgroup C3). In this series Ca 15-3 was increased in 9 of 13 patients (subgroup C3alpha), while the remaining four patients (subgroup C3beta) presented values within the normal range. On 26 group C patients who were negative for PCa to third biopsy (subgroup C4), 24 patients had Ca 15-3 levels within normal range (subgroup C4alpha) with histologic findings of BPH in 23 cases and granulomatous chronic prostatitis in one case, while two patients (subgroup C4beta) had elevated Ca 15-3 concentrations associated with lymphoplasmacytic chronic prostatitis. We hypothesize that Ca 15-3, as a specific tumor marker, could be an interesting and inexpensive second step diagnostic tool for PCa in patients with borderline PSA and multiple negative prostate biopsies, as it could indicate whether a repeated biopsy should be performed in a short time, having excluded other concomitant tumors. However, further prospective studies will be necessary to confirm this hypothesis.
Subject(s)
Adenocarcinoma/blood , Adenocarcinoma/diagnosis , Biomarkers, Tumor/blood , Mucin-1/blood , Prostatic Neoplasms/blood , Prostatic Neoplasms/diagnostic imaging , Aged , Biopsy, Needle , Endosonography , False Negative Reactions , Humans , Male , Middle Aged , Prospective Studies , Prostate-Specific Antigen/blood , Sensitivity and SpecificityABSTRACT
BACKGROUND: The purpose of this study was to report our experience on the use of Mepartricine in the treatment of chronic and sub-acute prostatitis and to analyse, on the basis of the literature, the role of estrogens, the target of Mepartricine in the development and maintenance of prostatic inflammatory reactions. METHODS: In a retrospective study the data of 110 patients who presented with lower urinary tract symptoms suggestive of prostatitis, from January 1994 to February 1999 have been evaluated: 65 of this patients had an abacterial prostatitis, and 45 a bacterial prostatitis. The Mearers-Stamey test was used to localize inflammation and pathogens to prostate. The clinical symptoms presented were essentially pelvic and perineal pain and irritative and obstructive voiding symptoms. The treatment was based on antibiotic therapy indicated by the sensitivity to antibiotic assay. In abacterial prostatitis, in cases of Chlamidia, Mycoplasma and Ureaplasma positivity, the treatment was based on macrolides and tetracycline use. All the patients received Mepartricine by oral supply, 1 daily tablet (40 mg) for 60 days. RESULTS: After two months of treatment remarkable improvements in symptoms were obtained despite the persistent bacteriological positivity in the prostatic secretion in 68% of cases. Therefore antinflammatory antiedemic and decongestant effects of Mepartricine on prostatic inflammation, are observed. CONCLUSIONS: The data of the literature show data estrogens modulate inflammatory reactions: it is possible that their decrease can produce, at prostatic level, antinflammatory effects improving urethro-prostatic bladder functions. Personal experience seems to confirm this supposition and so we think that Mepartri-cine can be considered and excellent coadjuvant in the treatment of prostate inflammation, independent of etiology.
Subject(s)
Mepartricin/therapeutic use , Prostatitis/drug therapy , Adult , Humans , Male , Middle Aged , Retrospective StudiesABSTRACT
The authors have analyzed the most recent additions to the literature of immunohistochemical and molecular assessment of acquired urethral strictures and report on their data obtained in a selected clinical series. Innovative immunohistochemical studies in patients presenting with plurirecurrent symptoms suggest that urethral mesenchymal changes caused by tissue de-epithelialization may be the underlying cause of stricture. This condition may be congenital or acquired. It may determine aberrant connective tissue formation induced by abnormal fibroblastic activation with formation of over abundant hyperdense collagen scar tissue.
Subject(s)
Urethral Stricture/genetics , Urethral Stricture/metabolism , Aged , Collagen/metabolism , Collagen/physiology , Humans , Immunohistochemistry , Male , Microscopy, Electron , Microscopy, Electron, Scanning , Middle Aged , Recurrence , Reference Values , Urethra/metabolism , Urethra/pathology , Urethral Stricture/pathologyABSTRACT
PURPOSE: This study was conducted by nine urology departments in southern Italy to assess the efficacy of and tolerance to treatment of recurrent urethral stricture using a permanent prosthesis. PATIENTS AND METHODS: Since 1992, 99 prostheses have been implanted to treat inflammatory and iatrogenic (seven departments) or all types (two departments) of urethral strictures. The Urolume Wallstent was used in 94 cases. Three centers implanted more than one prosthesis when this was indicated. Local anesthesia was used by six centers, spinal anesthesia by two, and local or general by one. At three centers, urethrotomy was performed immediately prior to implantation; two centers used dilation to 30F, and two centers performed urethrotomy 24 or 36 hours before implantation. The median follow-up is 29.1 months (range 3-53 months). RESULTS: The results were good in 52%, fair in 34%, and poor in 14% of patients. The maximum flow rate increased >75% in 82% of patients. All departments reported complete reepithelialization of the urethra by 6 months. The short-term complications (7-28 days) were perineal discomfort (86%) and dribbling (14%). The long-term complications were painful erection (44%), mucous hyperplasia (44%), recurring stricture (29%), and incontinence (14%). All departments performed resection for hyperplasia in many cases. CONCLUSION: Permanent urethral endoprostheses can produce excellent results in patients with recurrent urethral strictures.
Subject(s)
Cystoscopy/methods , Prostheses and Implants , Prosthesis Implantation/instrumentation , Urethra/surgery , Urethral Stricture/surgery , Adult , Humans , Italy , Male , Retrospective Studies , Secondary Prevention , Treatment Outcome , Urology Department, HospitalABSTRACT
In this work the authors make a description of the rare testis tumors. They underline the several histologic features and the difficulty of early diagnosis due to the absence of reliable markers, and as for the malignancies the unclear role of the radio and chemotherapy. The difference in terms of classification and of lack in the therapeutic standards is clear if compared with the germ cell tumors. These pathologies require an early surgical approach by using the available diagnostic imaging tools and bioptic examination.
Subject(s)
Testicular Neoplasms/therapy , Humans , Male , Neoplasm Metastasis , Testicular Neoplasms/pathologyABSTRACT
We have started study after a publication (1) about our experience on 1376 urethrotomies executed above 784 patients; the 11% of these stenosis have been consequent on endoscopic or open surgery. In the 23% of these patients we have made more than two urethrotomies and in 4% of these the endoscopic operation has not been resolutive. We described the use of the urethral wall stent in 13 patients with recurring urethral strictures. The stainless steel stent is self expanding when released from its endoscopic introducer. We have desobstructed the 100% of the patients and obtained a max flow between 15 and 24 ml/sec. We haven't had problems of re-epithelialization if excluded two patients where observed a stabilized exuberant re-epithelialization without uroflowmetry variations. It is considered that this endoscopic technique offers a simple, safe and effective alternative to multiple dilatations and urethrotomies in patients with bulbar urethral strictures.
Subject(s)
Stents , Urethral Stricture/surgery , Catheterization , Humans , Postoperative Complications , Recurrence , UrodynamicsABSTRACT
An experimental study on tracheal reconstruction using a jejunal loop autograft, is reported. Eight dogs divided into 2 groups have been used. In the first group the jejunal loop was prepared using a single vascular pedicle including both the artery and the vein and was revascularized with the superior thyroid artery and its collateral vein. In the second group the jejunal loop was prepared with two different vascular pedicles, revascularizing the artery with the superior thyroid artery and the vein with the jugular vein. In this group a sylastic T-tube was placed inside the loop. The procedure and preliminary results, are reported.
Subject(s)
Jejunum/transplantation , Trachea/surgery , Animals , Dogs , Jejunum/anatomy & histology , Trachea/anatomy & histologyABSTRACT
The peculiar functional structure of the Z-line in the obliquely striated muscles of some feather stars is described. It is known that cross-striated muscles are characterized by linear and continuous Z-bands, and obliquely striated muscles by disconnected, obliquely aligned Z-elements. Owing to this discontinuous organization, the sarcomere can perform wide active lengthenings, shortenings, and even 'super-elongations' in the helical fibres. In contrast, the obliquely striated fibres of crinoids show markedly continuous and homogeneous oblique Z-lines; such a structure is not compatible with 'super-performances' like sliding and shearing of the sarcomere elements, but instead could allow functions comparable to those characteristic of a cross-striated muscle (quick, short movements, mechanically amplifiable by bone levers). This odd situation, only interpretable in terms of evolutionary constraint, could be considered opposite and symmetrical to that of cross-striated 'super-contracting' muscles, where the Z-line is exceptionally fragmented to allow the sarcomere to super-contract. The possible architecture of a significant parameter such as the Z-line, which determines muscle fibre potential capacities, is analysed in detail: through qualitative-quantitative evaluation of electron micrographs, supported by statistical analysis of the data; and by computer simulations. The data obtained suggest that the most realistic conformation of the whole Z-complex in these muscles consists of a multiple system of continuous, ribbon-like helical planes running in parallel along the fibre from end to end and regularly cutting it with a constant thickness. The proposed model seems morphologically compatible with the experimentally verified situations and functionally compatible with the mechanical requirements for a normal contraction and for a balanced distribution of the involved strengths.