Outcomes of GatekeeperTM prosthesis implantation for the treatment of fecal incontinence: a multicenter observational study

Gatekeeper™ Prostheses Implants in the Anal Canal for Gas Incontinence and Soiling: Long-Term Follow-Up

Introduction: Although several treatments for faecal incontinence are available, gas incontinence (GI) and soiling are difficult to manage. The aim of this study is to evaluate Gatekeeper™ for this subtype of faecal incontinence. Methods: Prospective single-centre case series. Patients with mainly soiling and/or GI were treated with polyacrylonitrile prostheses. An evaluation was performed with a 3-week continence diary. St. Mark's score and a Visual Analogue Scale (VAS) were used to study the patient's continence perception and surgical satisfaction, at baseline and 1, 3, 6, 12, and 24 months postoperatively. 3D-Endoanal Ultrasound and Anorectal Manometry were performed at baseline and postoperatively. Results: A total of 13 patients were enrolled (11 women), aged (median (IQR)) 62 (13) years, and all implants were uneventful. A significant reduction in soiling and GI episodes was documented at 1 year, 7 (18) baseline days of soiling/3 weeks vs. 2 (4) (p = 0.002); 13 (13) baseline episodes of GI/3 weeks vs. 4 (10) (p = 0.01). This improvement was correlated with a significant increase in VAS (0-10), 3 (2, 5) baseline vs. 7 (1, 5) (p = 0.03), and maintained throughout the follow-up. There was complete remission or significant improvement defined as >70% reduction in gas and soiling days in 6 patients at 2 years follow-up. Soiling episodes were reduced ≥70% in 8/11 patients (72.7%). Nine (70%) patients would repeat the treatment. Conclusions: Gatekeeper™ is a safe, minimally invasive treatment for soiling and GI. A significant reduction in soiling and GI was observed in our series, with a better response to soiling. Most of the patients would repeat the treatment. Other studies are needed to confirm these findings in this subgroup of FI patients.

Endosonographic monitoring of Sphinkeeper® prostheses movements: does physical activity have an impact?

The Sphinkeeper® procedure for treating faecal incontinence (FI) may be associated with potential implant migration (IM) and dislocation (ID), with considerable variations regarding their occurrence and effects on consecutive functional outcome. This study assessed IM and ID following the Sphinkeeper® procedure and its correlation with physical activity. This was a prospective observational clinical study of ten patients undergoing Sphinkeeper® operation due to FI between August 2020 and November 2020 at the Medical University of Vienna. Patients were followed-up after 1, 2, 3 and 6 months and 1 year postoperatively. Each follow-up visit included endosonographic monitoring of protheses location and manometric examinations. Additionally, functional outcome and physical activity were assessed using validated standardized questionnaires. The median number of prostheses implanted was 10 (IQR 9-10). The St. Mark's incontinence (SMS) score improved significantly until the last follow-up (p = 0.049), without observing a significant effect on the physical SF-12 score. The median rate of implants leading to IM and ID was 3 (range 1-4) and 2 (range 1-2) after 3 months of follow-up. A strong association of deltaSMS with number of dislocated prostheses at one month after Sphinkeeper® implantation was observed (r = 0.654, p = 0.078). Physical activity, assessed by the international physical activity questionnaire, did not have an impact on the correct prosthesis placement (1 month: p = 0.527; 2 months: p = 0.886; 3 months: p = 0.180; 6 months: p = 0.111). IM and ID of Sphinkeeper® prostheses occurred frequently early after surgery and affected functional outcome negatively. Physical activity did not have an influence on the implants displacement.

Long-term outcome after SphinKeeper® surgery for treating fecal incontinence-who are good candidates?

PURPOSE

The efficacy of the novel SphinKeeper® procedure for the treatment of fecal incontinence (FI) is not yet well defined. This study aimed to assess long-term functional outcomes after SphinKeeper® surgery.

METHODS

We included 32 patients with FI (28 female), who were operated at a tertiary referral center between August 2018 and September 2021. Functional outcome and quality of life were evaluated prospectively using validated questionnaires before and after surgery. Additionally, endoanal ultrasound and anal manometry were conducted prior and after SphinKeeper® implantation. Predictive parameters for treatment success were defined.

RESULTS

The mean follow-up time was 22.62 ± 8.82 months. The St. Mark's incontinence score decreased significantly after surgery (median preoperative = 19 (IQR 17-22) versus median last follow-up = 12 (IQR 8-16), p = 0.001). Similarly, physical short-form health survey showed a significant improvement after SphinKeeper® implantation (p = 0.011). Patients with a higher degree of internal sphincter defect showed an improved objective therapy success (r = 0.633, p = 0.015) after SphinKeeper® operation, whereas the type and severity of FI had no impact on the functional outcome. Notably, a higher number of dislocated prostheses (r = 0.772, p = 0.015) showed a significant correlation with reduced improvement of incontinence.

CONCLUSION

The SphinKeeper® procedure showed a significant long-term functional improvement in over half of the patients. Patients with a higher internal sphincter defect benefited most, whereas dislocation of the prostheses was associated with less favorable results.

Clinical effectiveness and safety of self-expandable implantable bulking agents for faecal incontinence: a systematic review

PURPOSE

The purpose of this systematic review is to evaluate whether self-expandable implantable vs non-self-expandable injectable bulking agents (second-line therapies) are equal/superior in terms of effectiveness (severity, quality of life [QoL]) and safety (adverse events) for faecal incontinence (FI).

METHODS

A systematic review was conducted, and five databases were searched (Medline via Ovid, Embase, Cochrane Library, University of York Centre for Reviews and Dissemination, and International Network of Agencies for Health Technology database). In-/exclusion criteria were predefined according to the PICOS scheme. The Institute of Health Economics risk of bias (RoB) tool assessed studies' internal validity. According to the Grading of Recommendations, Assessment, Development and Evaluation approach, the strength of evidence for safety outcomes was rated. A qualitative synthesis of the evidence was used to analyse the data.

RESULTS

The evidence consists of eight prospective single-arm, before-after studies (166 patients) fulfilling the inclusion criteria for assessing clinical effectiveness and safety of implantable bulking agents. FI severity statistically significantly improved in five of seven studies rated by the Cleveland Clinic FI Score and in three of five studies measured by the Vaizey score. Statistically significant improved disease-related QoL was found in one of five studies measured by the FI QoL Score and in one of two studies rated by the American Medical Systems score. Procedure-related adverse events occurred in 16 of 166 patients (i.e., intraoperative complications, anal discomfort and pain). Device-related adverse events occurred in 48 of 166 patients, including prostheses' dislodgement and removed/extruded prostheses. Studies were judged with moderate/high RoB. The strength of evidence for safety was judged to be very low.

CONCLUSION

Implantable bulking agents might be an effective and safe minimally invasive option in FI treatment if conservative therapies fail. FI severity significantly improved, however, effects on QoL need to be explored in further studies. Due to the uncontrolled nature of the case series, comparative studies need to be awaited.

An evaluation of the long-term effectiveness of Gatekeeper™ intersphincteric implants for passive faecal incontinence

Background

Implantation of Gatekeeper™ prostheses presents an option for the treatment of passive faecal incontinence (FI). Whilst preliminary results are encouraging, long-term data regarding its sustained benefit are limited. The aim of this study was to assess and evaluate the long-term clinical function and quality of life of patients with passive faecal incontinence who were treated with Gatekeeper™ prostheses.

Methods

This was a single centre, single surgeon retrospective study of prospectively collected clinical data in patients with FI treated between June 2012 and May 2019. Patients with passive FI with symptoms refractory to conservative treatment and endoanal ultrasonography showing intact or disrupted internal anal sphincter were included. Formal clinical and quality of life assessments were carried out using the St. Mark’s Incontinence Score (SMIS) and Faecal Incontinence Quality of Life (FIQoL) questionnaires at baseline, 3 months, 6 months, 12 months and then annually. Endoanal ultrasonography was performed both before and after surgery.

Results

Forty patients (14 males, 26 females) with a median age of 62.5 (range 33–80) years were treated with the Gatekeeper™ implant. The majority of patients (87.5%) received six implants. There were no peri or post-operative complications. Prosthesis migration was observed in 12.5% patients. The median follow-up duration was 5 years (interquartile range (IQR) 3.25–6.00 years). A sustained improvement in median SMIS and FIQoL scores from baseline to follow-up was noted. Significant differences were observed between the median baseline SMIS score and last follow-up score of 16.00 (IQR 15.00–16.75) to 7.00 (IQR 5.00–8.00) respectively (p < 0.001), a 56.25% decrease. The overall median FIQoL score showed a significant improvement from 7.95 (IQR 7.13–9.48) to 13.15 (IQR 12.00–13.98) (p < 0.001) a 65.40% increase.

Conclusions

Gatekeeper™ implantation is a safe approach to treating passive FI and is minimally invasive, reproducible and has minimal complications. Long-term sustained clinical improvement is achievable beyond 5 years. Careful patient selection is paramount, as is consistency of technique and follow-up protocol.

Critical appraisal of international guidelines for the management of fecal incontinence in adults: is it possible to define what to do in different clinical scenarios?

Fecal incontinence (FI) is a complex often multifactorial functional disorder which is associated with a significant impact on patients’ quality of life. There is a broad spectrum of symptoms, and degrees of severity and diverse patient backgrounds. Several treatment algorithms from different professional societies and experts are available in the literature. However, no consensus has been reached on several aspects of FI management. We performed a critical review of the most recently published guidelines on FI, emphasising the lack of consensus, highlighting specific topics mentioned in each of the guidelines that are not covered in the others and defining the treatment proposed in different clinical scenarios.

Sphinkeeper Procedure for Treating Severe Faecal Incontinence-A Prospective Cohort Study

(1) Background: The Sphinkeeper implantation for faecal incontinence (FI) is a novel surgical procedure with limited data on its clinical efficacy. Therefore, we aimed to assess the functional outcome following Sphinkeeper surgery in patients with refractory FI. (2) Methods: Between 2018 and 2020, eleven consecutive patients (9 female) with FI met the inclusion criteria and were enrolled for surgery. Functional outcome and quality of life were evaluated by standard questionnaires pre- and post-surgery. Migration of protheses was demonstrated by 3D endoanal ultrasound. The median follow-up time was eight months (range 3–18 months). (3) Results: The median age was 75 years (range 46–89 years) with a median BMI of 27.4 (range 21.2–30.1). The median number of implanted prostheses per intervention was nine (range 9–10). We found no intraoperative or early postoperative complications. After two months, two prostheses in one patient had to be removed due to pain at the perianal skin site. The median St. Mark’s incontinence score decreased significantly from 22 to 13 points (p = 0.008). The SF-12 showed a significant improvement (35.9 versus 46.3) after surgery (p = 0.028). A migration of at least one prosthesis was observed in ten patients (91%). Six (60%) prostheses were found at the same level in another ten patients. (4) Conclusion: Sphinkeeper implantation is a promising surgical technique for patients with severe FI. The complication rate is low, and short-term functional improvement can be achieved even in severe forms of FI. Migration of implants commonly occurs.

Implant of Self-Expandable Artificial Anal Sphincter in Patients With Fecal Incontinence Improves External Anal Sphincter Contractility

BACKGROUND

External anal sphincter contractility significantly contributes to control the passage of stool. An artificial anal sphincter placed into the intersphincteric space is a safe and effective procedure to treat fecal incontinence, even if its mechanism of action has not been fully elucidated.

OBJECTIVE

The aim of this study was to evaluate external anal sphincter contractility changes after a self-expandable hyexpan prostheses was implanted into the intersphincteric space of the anal canal and clinical outcomes compared.

DESIGN

This was a prospective clinical study.

SETTINGS

The study was conducted at a university teaching hospital.

PATIENTS

Consecutive patients affected by fecal incontinence for at least 6 months after failure of conservative treatment were included.

INTERVENTIONS

All of the patients underwent 10-prostheses implantation and were examined preoperatively and postoperatively by endoanal ultrasound and anorectal manometry.

MAIN OUTCOME MEASURES

Fecal incontinence symptoms were assessed by severity scores. The external anal sphincter muscle tension was calculated using a specific equation.

RESULTS

Thirty-nine patients (34 women; median age = 68 y) were included in the study; no morbidity was registered. After a median follow-up period of 14 months, both the median maximum voluntary squeeze pressure and the median inner radius of the external anal sphincter significantly increased. A statistically significant increase of external anal sphincter muscle tension was detected. A decrease of any fecal incontinence symptom and an improvement in severity scores were observed at the last follow-up examination. The external anal sphincter contractility was significantly higher in patients reducing incontinence episodes to solid stool by >50% and improving their ability to defer defecation for >15 minutes.

LIMITATIONS

This was a single-center experience with a relatively small and heterogeneous sample size, patients with a potentially more severe disease because our institution is a referral center, and an absence of quality-of-life evaluation.

CONCLUSIONS

Artificial anal sphincter implantation improved the external anal sphincter muscle tension; there was a positive correlation between its increase and the clinical outcome. See Video Abstract at http://links.lww.com/DCR/B468.

IMPLANTE DE ESFNTER ANAL ARTIFICIAL AUTOEXPANDIBLE EN PACIENTES CON INCONTINENCIA FECAL MEJORA LA CONTRACTILIDAD DEL ESFNTER ANAL EXTERNO

ANTECEDENTES:La contractilidad del esfínter anal externo contribuye significativamente al control del paso de las heces. Un esfínter anal artificial colocado en el espacio interesfinteriano es un procedimiento seguro y eficaz para tratar la incontinencia fecal, incluso si su mecanismo de acción no se ha definido por completo.OBJETIVO:El objetivo de este estudio fue evaluar los cambios en la contractilidad del esfínter anal externo después de la implantación de una prótesis de hyexpan autoexpandible en el espacio interesfinteriano del canal anal y comparar los resultados clínicos.DISEÑO:Estudio clínico prospectivo.ENTORNO CLINICO:El estudio se realizó en un hospital universitario.PACIENTES:Pacientes consecutivos afectados por incontinencia fecal durante al menos 6 meses, tras fracaso de tratamiento conservador.INTERVENCIONES:Todos los pacientes fueron sometidos a la implantación de 10 prótesis, y fueron examinados pre y postoperatoriamente mediante ecografía endoanal y manometría anorrectal.PRINCIPALES MEDIDAS DE VALORACION:Los síntomas de incontinencia fecal se evaluaron mediante puntuaciones de gravedad. La tensión del músculo del esfínter anal externo se calculó mediante una formula específica.RESULTADOS:Treinta y nueve pacientes (34 mujeres; mediana de edad 68 años) fueron incluidos en el estudio; no se registró morbilidad. Después de un período de seguimiento medio de 14 meses, tanto la presión de compresión voluntaria máxima media como el radio interior medio del esfínter anal externo aumentaron significativamente. Se detectó un aumento estadísticamente significativo de la tensión del músculo del esfínter anal externo. En el último examen de seguimiento se observó una disminución de cualquier síntoma de incontinencia fecal y una mejora en las puntuaciones de gravedad. La contractilidad del esfínter anal externo fue significativamente mayor en los pacientes que redujeron los episodios de incontinencia a heces sólidas en más del 50% y mejoraron la capacidad para diferir la defecación durante más de 15 minutos.LIMITACIONES:Experiencia de un solo centro; tamaño de muestra relativamente pequeño y heterogéneo; pacientes con una enfermedad potencialmente más grave porque nuestra institución es un centro de referencia; ausencia de evaluación de la calidad de vida.CONCLUSIONES:La implantación del esfínter anal artificial mejoró la tensión muscular del esfínter anal externo; hubo una correlación positiva entre su aumento y el resultado clínico. Consulte Video Resumen en http://links.lww.com/DCR/B468.

Surgical Treatment Alternatives to Sacral Neuromodulation for Fecal Incontinence: Injectables, Sphincter Repair, and Colostomy

Fecal incontinence is a prevalent health problem that affects over 20% of healthy women. Many surgical treatment options exist for fecal incontinence after attempts at non-operative management. In this article, the authors discuss surgical treatment options for fecal incontinence other than sacral neuromodulation.

Tools for fecal incontinence assessment: lessons for inflammatory bowel disease trials based on a systematic review

BACKGROUND

Fecal incontinence is a disabling condition affecting up to 20% of women.

OBJECTIVE

We investigated fecal incontinence assessment in both inflammatory bowel disease and non-inflammatory bowel disease patients to propose a diagnostic approach for inflammatory bowel disease trials.

METHODS

We searched on Pubmed, Embase and Cochrane Library for all studies on adult inflammatory bowel disease and non-inflammatory bowel disease patients reporting data on fecal incontinence assessment from January 2009 to December 2019.

RESULTS

In total, 328 studies were included; 306 studies enrolled non-inflammatory bowel disease patients and 22 studies enrolled inflammatory bowel disease patients. In non-inflammatory bowel disease trials the most used tools were the Wexner score, fecal incontinence quality of life questionnaire, Vaizey score and fecal incontinence severity index (in 187, 91, 62 and 33 studies). Anal manometry was adopted in 41.2% and endoanal ultrasonography in 34.0% of the studies. In 142 studies (46.4%) fecal incontinence evaluation was performed with a single instrument, while in 64 (20.9%) and 100 (32.7%) studies two or more instruments were used. In inflammatory bowel disease studies the Wexner score, Vaizey score and inflammatory bowel disease quality of life questionnaire were the most commonly adopted tools (in five (22.7%), five (22.7%) and four (18.2%) studies). Anal manometry and endoanal ultrasonography were performed in 45.4% and 18.2% of the studies.

CONCLUSION

Based on prior validation and experience, we propose to use the Wexner score as the first step for fecal incontinence assessment in inflammatory bowel disease trials. Anal manometry and/or endoanal ultrasonography should be taken into account in the case of positive questionnaires.

Implantable Agents for Fecal Incontinence: An Age-Matched Retrospective Cohort Analysis of GateKeeper versus SphinKeeper

Background. We aim to evaluate morphofunctional changes of the sphincter complex after GateKeeper (GK) and SphinKeeper (SK) procedures and correlate these with symptom improvement. Methods. Ten consecutive females undergoing SK implant were age-matched with a cohort of 10 females who previously underwent the GK procedure. Patients in the SK and GK groups underwent implantation of 10 and 6 prostheses, respectively. Muscle tension (Tm), expressed in millinewtons per centimetre squared, mN (cm²)^-1, was calculated using the equation Tm = P(r_i)(tm)^-1, where P is the average maximum squeeze pressure and r_i and tm the inner radius and thickness of the external anal sphincter, respectively. The pre- and postimplant changes in Tm and Cleveland Clinic Fecal Incontinence Score (CCFIS) were tested by linear and Poisson regression models, respectively. Results. The CCFIS significantly improved in both groups at 12-month postimplantation. Although not reaching statistical significance, symptom improvement after SK was 33% above that observed after GK (P = .088). Compared to the baseline, a significant increase in Tm was observed in both groups at 12 months (GK, 508.1 [478.8-568.0] vs 864.4 [827.0-885.8] mN (cm²)^-1; SK, 528.0 [472.7-564.0] vs 858.6 [828.0-919.6] mN (cm²)^-1, P = .005). Compared to the GK group, Tm was significantly higher in patients after SK implant (158.3 mN (cm²)^-1 [95% confidence interval, 109.6-207.0]; P < .001), after controlling for baseline values, at 12-month postimplantation. Conclusions. GK and SK are safe and effective treatments for FI with good short-term clinical outcomes. Comparative analysis showed superiority of SK over GK in terms of gain in Tm, with borderline significantly better improvement in symptoms. Larger studies are needed to confirm these findings.

Middle-term Outcomes of Gatekeeper Implantation for Fecal Incontinence

BACKGROUND

Intersphincteric injectable bulking agents are one of the current treatment options for fecal incontinence, failing behavioral and medical therapy. Gatekeeper showed promising short-term results, but long-term outcomes are unknown.

OBJECTIVE

The purpose of this study was to clinically evaluate a prospective cohort of fecal incontinence patients up to 36 months after implantation of Gatekeeper.

DESIGN

This was a prospective clinical study.

SETTINGS

The study was conducted at a large university tertiary care hospital.

PATIENTS

Consecutive female patients were eligible if fecal incontinence onset was ≥6 months before the first visit and symptoms were refractory to standard conservative measures.

INTERVENTIONS

All of the patients underwent implantation of 4 or 6 Gatekeeper prostheses. Three-dimensional endoanal ultrasonography and high-resolution anorectal manometry were performed preoperatively and postoperatively at 2 and 3 months after implantation.

MAIN OUTCOME MEASURES

The Cleveland Clinic Fecal Incontinence score was calculated at baseline and 1, 3, 12, 24, and 36 months postoperatively.

RESULTS

Twenty patients (all women; median age, 59 y) were enrolled, and all implants were uneventful. Postoperative endoanal ultrasonography showed normal prosthesis localization in 16 patients (80%). At manometry, mean anal resting pressure significantly improved (57.8 ± 7.5 mm Hg; p = 0.0004). Mean preoperative Cleveland Clinic Fecal Incontinence score was 12.4 ± 1.8, with significant improvements initially documented at 3 months (4.9 ± 1.5; p < 0.0001) and sustained up to 36 months (4.9 ± 1.7; p < 0.0001). Patients receiving only 4 (compared with 6) prostheses and those experiencing pudendal neuropathy (compared with those who did not) showed significantly higher Cleveland Clinic Fecal Incontinence score values in the middle term.

LIMITATIONS

The study was limited by its small sample size and absence of quality-of-life data.

CONCLUSIONS

Initial improvements after Gatekeeper implantation for fecal incontinence are sustained in the middle term. Accurate preoperative evaluation of coexistent clinical conditions that may negatively affect outcomes is recommended for patient selection. See Video Abstract at http://links.lww.com/DCR/B109. RESULTADOS A MEDIANO PLAZO EN LA IMPLANTACIÓN DE GATEKEEPER PARA LA INCONTINENCIA FECAL: Los agentes de volumen inyectables interesfintéricos, son opciones actuales de tratamiento para la incontinencia fecal, ante fallas de terapias conductuales y médicas. Gatekeeper mostró resultados prometedores a corto plazo, pero resultados a largo plazo aún son desconocidos.Evaluar clínicamente una cohorte prospectiva de pacientes con incontinencia fecal, hasta 36 meses después de la implantación de Gatekeeper.Estudio clínico prospectivo.El estudio se realizó en un gran hospital universitario de atención terciaria.Fueron elegibles pacientes femeninas consecutivas, si el inicio de la incontinencia fecal, fue al menos 6 meses antes de la primera visita, y que los síntomas fueron refractarios a las medidas conservadoras estandarizadas.Todas las pacientes fueron sometidas a implantación de 4 o 6 prótesis Gatekeeper. Se realizó ecografía endoanal de 3D y manometría anorrectal de alta resolución, antes de la implantación y después a los 2 y 3 meses.Se calculó el puntaje de incontinencia fecal de la Cleveland Clinic al inicio, y a los 1, 3, 12, 24 y 36 meses después de la operación.Se inscribieron veinte pacientes (todas mujeres; con edad media de 59 años), y todos los implantes transcurrieron sin incidentes. La ecografía endoanal postoperatoria, mostró localización normal de la prótesis en 16 (80%) pacientes. A la manometría, la presión media de reposo anal, mejoró significativamente (57.8 ± 7.5 mmHg, p = 0.0004). La puntuación media preoperatoria de la incontinencia fecal de la Cleveland Clinic, fue de 12.35 ± 1.75, con mejoras significativas documentadas inicialmente a los 3 meses (4.9 ± 1.5, p <0.0001) y sostenidas hasta los 36 meses (4.9 ± 1.7, p <0.0001). Los pacientes que recibieron solo 4 prótesis (en comparación con 6) y que padecían neuropatía pudenda (en comparación con aquellas que no la padecían), mostraron valores de puntaje de Incontinencia Fecal de la Clínica Cleveland, significativamente más altos en el mediano plazo.El tamaño pequeño de la muestra y la ausencia de datos en calidad de vida.Las mejoras iniciales después de la implantación de Gatekeeper para la incontinencia fecal, se mantienen en el mediano plazo. Para la selección de pacientes, se recomienda una precisa evaluación preoperatoria de las condiciones clínicas coexistentes, que puedan afectar negativamente los resultados. Consulte Video Resumen en http://links.lww.com/DCR/B109.

Gatekeeper Improves Voluntary Contractility in Patients With Fecal Incontinence

Background. Gatekeeper (GK) has shown to be safe and effective in patients with fecal incontinence (FI). We aimed to understand its mechanism of action by comparing pre- and post-implant change in the external anal sphincter (EAS) contractility. Methods. Study of EAS contractility was conducted in 16 FI females (median age = 69 years) before and after implant of 6 GK prostheses. Muscle tension (Tm), expressed in millinewtons per centimeter squared, mN(cm²)⁻¹, was calculated using the equation Tm = P(r_i)(tm)⁻¹, where P is the average maximum squeeze pressure and r_i and tm the inner radius and thickness of the EAS, respectively. The effect of a predefined set of covariates on Tm was tested by restricted maximum likelihood models. Results. Compared with baseline, despite unchanged tm (2.7 [2.5-2.8] vs 2.5 [2.2-2.8] mm; P = .31 mm), a significant increase in P (median = 45.8 [26.5-75.8] vs 60.4 [43.1-88.1] mm Hg; P = .017), and r_i (12.4 [11.5-13.4] vs 18.7 [17.3-19.6] mm; P < .001) resulted in an increase in Tm (233.2 [123.8-303.2] vs 490.8 [286.9-562.4] mN(cm²)⁻¹; P < .001) at 12 months after GK implant. Twelve-month follow-up improvements were also observed on Cleveland Clinic FI score (8-point median decrease; P = .0001), St Marks FI score (10-point median decrease; P < .0001), and American Medical Systems score (39-point median decrease; P < .0001). Restricted maximum likelihood models showed that years of onset of FI was negatively associated with change in Tm (P = .048). Conclusions. GK-related EAS compression positively influences muscle contractility by increasing r_i, with consequent increase in Tm (length-tension relationship). Further studies are needed to confirm the long-term effectiveness of GK.