New synthetic resorbable mesh for open ventral hernia repair: the multicentre, single-arm, prospective study of Transorb self-gripping resorbable mesh in subjects undergoing open repair of ventral hernia in clean and clean-contaminated fields (RECOVER) protocol

Abstract

Introduction

Ventral hernia repair is among the most commonly performed general surgical procedures, during which meshes are often used to provide further support to weakened or damaged tissue surrounding the hernia repair site. Slowly resorbable synthetic meshes have recently emerged as a valid choice, as confirmed by published clinical evidence on launched meshes in the repair of ventral hernias showing satisfactory results. This study was designed to assess the performance and safety of a newly developed slowly fully resorbable self-gripping synthetic mesh in patients undergoing ventral hernia repair through open surgery in clean and clean-contaminated fields.

Methods and analysis

This is a prospective, multicentre, single-arm study that will be conducted in up to 20 European and US sites with a total of 163 patients undergoing midline primary or incisional ventral hernia repair in clean or clean-contaminated surgical fields using an open surgical approach and implanted with Transorb self-gripping resorbable mesh in retrorectus placement with or without transversus abdominis release. The study will include patients ≥18 years old, presenting at least one risk factor impairing wound healing. The primary endpoint will be hernia recurrence rate within 12 months, postoperatively evaluated by physical exam; secondary endpoints will include hernia recurrence rate within 1 month, 6 months, 24 months, 36 months, 48 months and 60 months postoperatively, hernia recurrence rate resulting in reoperation, hernia recurrence rate reported by patients, time to hernia recurrence, rate of surgical site occurrence (SSO), rate of SSO requiring procedural interventions, surgeon satisfaction and change in patient-reported pain and quality of life. The study will be considered successful if the upper limit of the 95% Bayesian credible interval for the primary endpoint is less than 14.2%. Descriptive statistics will be used to summarise secondary study endpoints unless otherwise noted.

Ethics and dissemination

The multicentre, single-arm, prospective study of Transorb self-gripping resorbable mesh in subjects undergoing open repair of ventral hernia study will be conducted in compliance with the Good Clinical Practice standards, ISO 14155:2020 and the Declaration of Helsinki. The publication plan includes dissemination of the 12-month, 24-month, 36-month, 48-month and 60 month study results.

Trial registration number

The RECOVER study has been registered at clinicaltrials.gov (NCT06449378).

Correspondence to Dr J. Scott Scott Roth; [email protected]

STRENGTHS AND LIMITATIONS OF THIS STUDY

• The multicentre, single-arm, prospective study of Transorb self-gripping resorbable mesh in subjects undergoing open repair of ventral hernia study includes long-term follow-up assessments up to 60 months post surgery to collect data to cover mesh resorption profiles and reach a higher level of scientific validity.

• The prospective, international, multicentre design of the study allows for the collection of real-time data ensuring clear cause-and-effect relationships by following subjects forward in time and guarantees inclusion of all types of repair habits by conducting the research in up to 20 European and US sites.

• A Bayesian adaptive design allows for the possibility of stopping enrolment early without biasing the primary endpoint and allows for quicker access to this therapy for patients.

• The single-arm design of the study—selected to assess the performance and safety of a new mesh without evaluating its superiority over similar devices—may lead to confounding factors affecting the data interpretation due to a lack of a control group.

• The study was not designed to test subgroup differences for fixation methods and Centers for Disease Control and Prevention classification.

Background

A ventral hernia is defined as a protrusion of abdominal cavity content or preperitoneal fat through a defect or weakness in the ventral abdominal wall, which can occur spontaneously (primary hernia) or following a surgical incision (incisional hernia).^{1 2}

Ventral hernia repair is performed surgically and, although it represents one of the most common general surgical procedures, it can be challenging depending on the surgical technique used and/or patient comorbidities and complexity of the hernia. Ventral hernia repair can be performed through open or minimally invasive procedures.¹

During ventral hernia repair, meshes are used to confer additional support to weakened or damaged tissues. Permanent synthetic meshes are strongly recommended, providing long-term durability and strength to reinforce the weakened abdominal wall.^{3 4} However, their use may be associated with infections and other mesh-related complications, including long-term complications.^{5 6}

In contaminated ventral hernia repairs—associated with an increased risk of postoperative infection, bowel adhesion, mesh extrusion and erosion, fistula formation, seroma and pain—surgeons are reluctant to use permanent meshes.⁷ Synthetic, slowly resorbable meshes have been designed to reduce these risks while maintaining their mechanical strength during the early stages of healing of the abdominal wall and gradually resorb as abdominal wall connective tissue develops.^{3 8} Several studies have demonstrated that synthetic resorbable meshes perform well in terms of hernia recurrence in clean-contaminated and contaminated fields.^{7 9}

The synthetic Transorb self-gripping resorbable mesh (Transorb mesh) (Sofradim Production, Medtronic) has been recently developed for the reinforcement of the abdominal wall during ventral hernia repair procedures performed through open surgery. The Transorb mesh is the first and only fully resorbable, macroporous mesh presenting grips on one side (Medtronic Progrip technology). While the macroporous design provides strength to resist biomechanical stresses and allows tissue ingrowth, the grips facilitate the mesh positioning and fixation. In early 2024, the Transorb mesh received the US Food, Drug and Cosmetic Act (U.S. Food and Drug Administration (FDA)) 510(k) clearance for market release. The multicentre, single-arm, prospective study of Transorb self-gripping resorbable mesh in subjects undergoing open repair of ventral hernia (RECOVER) has been designed to evaluate the performance and safety of Transorb mesh in subjects undergoing open extraperitoneal ventral hernia repair, in clean and clean-contaminated surgical fields and presenting at least one risk factor impairing wound healing—a condition closely associated with the formation of incisional hernias.¹⁰

Methods

Study design

This is a prospective, multicentre, single-arm study that will be conducted in both Europe (premarket) and the USA (postmarket). The study aims to evaluate the performance and safety of the new synthetic resorbable Transorb mesh implanted in retrorectus placement with or without transversus abdominis release (TAR) in patients undergoing open midline primary or incisional ventral hernia repair in clean (USA) (Centers for Disease Control and Prevention (CDC) class I) or clean contaminated (European Union (EU)) (CDC class II) surgical fields and presenting at least one risk factor impairing wound healing.

163 adult subjects will be enrolled in the study at up to 20 sites. Subjects who meet the eligibility criteria will be considered enrolled after having signed an informed consent form (ICF) and following initiation of mesh implantation. To avoid enrolment bias, each site will not enrol more than 25% (n=41) of the total number of subjects planned to be included in the study.

The study enrolment started in July 2024, with the last patient enrolled expected in summer 2025.

Ethics and dissemination

The RECOVER study will be conducted in compliance with the Good Clinical Practice international ethical and scientific quality standards, ISO 14155:2020 and the Declaration of Helsinki. If required, the study will require approval from the applicable institutional review boards (IRB)/ethics committees (EC) and regulatory authorities. The RECOVER study has been registered at clinicaltrials.gov (NCT06449378) and in local regulatory databases—if required.

The sponsor will perform on-site and/or remote study monitoring to ensure adherence to the study protocol, the clinical trial agreement and the applicable regulatory and local requirements.

Data curation

This study will use an electronic database and electronic case report forms to record data, which must be traceable to source documents. This study is compliant with the General Data Protection Regulation. All records and other information about subjects participating in this study are treated as confidential.

To minimise the possibility of unintentionally sharing information that can be used to re-identify private information, anonymised data and material may be made available to qualified researchers trained in human subject confidentiality protocols. Requests should be sent to the corresponding author and require approval by the study sponsor.

Patient consent

Subjects will sign an ICF, previously approved by the study site’s IRB or EC, confirming their voluntary agreement to participate in the study. A subject may only consent after having received all information about the aspects of the clinical investigation that are relevant to the decision to participate. ICF must be collected before the subject participates in any study-specific procedures. Investigators are also required to inform the subjects of any significant new findings related to their safety and well-being that emerge while the study is ongoing and that may influence the subject’s decision to continue participating in the study.

Dissemination of the study results

The RECOVER study publication plan includes the dissemination of the 12-month, 24-month, 36-month, 48-month and 60 month study results via conference abstracts and/or original papers—following consultation with the study steering committee and investigators.

Patient eligibility

Adults (≥18 years at the time of consent) with at least one risk factor impairing wound healing undergoing ventral hernia repair by open surgical approach and appropriate for implantation with the Transorb mesh will be eligible to participate in the study. The study inclusion and exclusion criteria are listed below:

Inclusion criteria

Subjects are eligible to be enrolled in the study only if they meet all the following criteria, assessed during subject screening:

• Subject has provided informed consent.

• Subject is 18 years of age or older at the time of consent.

• Subject is undergoing a planned, elective, open, single-staged repair of a midline primary or incisional ventral hernia using retrorectus/retromuscular mesh placement with or without TAR.

• Subject is expected to meet the following criteria:

  • In the USA: a class I/clean wound as defined by the CDC wound classification.

  • In Europe: a class I/clean wound or a class II/clean-contaminated wound.

• Subject has at least one of the following comorbid factors impairing wound healing:

  • Current smoker (subject who has smoked 100 cigarettes in his or her lifetime and who currently smokes).

  • Smoker with a minimum 20 pack year history (including former smokers).

  • Obesity, defined as body mass index (BMI) between 30 kg/m² and 39.9 kg/m².

  • Chronic obstructive pulmonary disease.

  • Diabetes mellitus.

  • History of wound infection.

  • Malnutrition (serum albumin less than 3.4 g/dL).

  • Coronary artery disease

  • History of chemotherapy.

  • Diagnosis of hypertension.

  • History of malignancy without evidence of active disease.

  • Renal insufficiency (serum creatinine concentration ≥2.5 mg/dL).

Exclusion criteria

• Subjects will be excluded from the study in case they meet any of the following preoperative and/or intraoperative criteria—assessed during the patient screening or following reduction of hernia and preparation of the retrorectus/retromuscular space for mesh placement, respectively:

Pre-operative exclusion criteria

• Subject is involved in another interventional drug or device study.

• Subject is unable or unwilling to comply with the study requirements or follow-up schedule.

• Subject has a history of:

  • Previous hernia repair involving retrorectus/retromuscular mesh placement or a component separation technique.

  • Allergic reactions to products poly-L-lactide, poly-trimethylene carbonate copolymer (PLLA/TMC), such as the Transorb mesh (refer to the Study device section for details).

  • Solid organ transplantation.

• Subject has current diagnosis/usage of:

  • BMI greater than or equal to 40.0 kg/m².

  • HIV.

  • Collagen formation disorder (such as Ehlers-Danlos syndrome and Marfan’s syndrome).

  • Liver cirrhosis and/or current ascites.

  • Renal disease requiring dialysis.

  • Bleeding disorder and/or cannot be removed from anticoagulants prior to surgery based on surgeon discretion and standard-of-care (excluding aspirin).

  • Chronic immunosuppression therapy (10 mg or greater of prednisone or equivalence/day).

  • Current or anticipated chemotherapy/radiotherapy during study period.

  • Stoma

  • Any systemic or local ongoing infection that is uncontrolled and/or requiring treatment such as antimicrobial medication (note: other uses of antimicrobial medications not excluded).

• Subject has a life expectancy of <5 years based on the judgement of the investigator.

• Subject is pregnant or is planning pregnancy within the 60-month follow-up period.

• Subject is breastfeeding or is planning to breastfeed during the study duration period.

• Subject has any other medical condition that precludes the subject from participation, in the opinion of the investigator.

• Subject is undergoing:

  • Minimally invasive hernia repair (ie, laparoscopic or robotic surgery).

  • An emergency surgery (ie, lifesaving procedures performed where subject is in imminent danger of death).

  • Multi-stage hernia repair.

  • Parastomal hernia repair.

  • Concomitant ostomy (creation or closure).

  • Any other additional anticipated surgery, if subsequent surgery that would jeopardise previous application of study device, in the opinion of the investigator.

Assessed/confirmed on day of surgery:

• Subject is American Society of Anesthesiology Class 4, 5 or 6.

• Subject has a BMI ≥40.0 kg/m².

• Subject is pregnant or is planning pregnancy within the 60-month follow-up period.

Intra-operative exclusion criteria

• Subject has existing mesh from previous surgery that the investigator was unable to completely remove.

• Subject has concomitant diastasis (>2 cm) that was not repaired.

• Hernia defect that will require a multistage repair.

• Subject no longer meets Inclusion criteria 4.

• Subject who will require more than a single piece of Transorb mesh or any other additional mesh.

• Subject with anticipated inability to achieve both midline anterior and posterior rectus fascia closure without excessive tension, and skin closure.

• Subject who is otherwise no longer eligible to receive Transorb mesh in open retrorectus/retromuscular position with or without TAR.

Patient assessment and follow-up

Assessment of patients will be performed at baseline, intraoperatively, at discharge, and at 1 month, 6 months, 12 months and 24 months postoperatively by a physical examination and at 36 months, 48 months and 60 months postoperatively by a phone call. During inperson follow-up visits, patients will be evaluated for hernia recurrence assessment via a physical exam, adverse events (AEs) and device deficiencies, usage of pain medications, drain usage and anticoagulation, patient-reported pain and quality of life (QoL) measured by the Abdominal Hernia-Q (AHQ) survey. During phone contact visits, assessment of hernia recurrence by the patients via the Ventral Hernia Recurrence Inventory (VHRI) questionnaire, AEs and device deficiency, usage of pain medications related to the repaired hernia site, pain at repair site and AHQ QoL measure will be performed. In case patients answer positively to any of the VHRI questions or report any AE requiring the investigator’s assessment, they will be asked to have an inperson visit.

Patient and public involvement statement

Patients and/or the public were not involved in this study.

Investigator selection

Study investigators must be qualified surgeons with experience in mesh implantation during ventral hernia repair procedures performed via open surgery, as well as the conduct of clinical trials.

Particularly, participating centres and investigators must be experienced in the surgical management of patients with mesh placement for the reinforcement of abdominal wall soft tissues where weakness exists in open retro-rectus procedures involving ventral hernia repair.

Investigators are qualified by education and training in accordance with hospital guidelines and relevant experience appropriate to the use of the product and associated procedures. Moreover, each investigator (together with the associated clinical study staff) will receive appropriate training on the clinical protocol, Transorb device and surgery-related study-specific requirements.

Study device

Transorb mesh is a newly developed, fully resorbable, monofilament macroporous synthetic mesh composed of a bidimensional PLLA/TMC monofilament textile, with monofilament PLLA/TMC absorbable grips on one side (Medtronic ProGrip technology) that facilitate the positioning of the mesh and contribute to its fixation. The macroporous structure provides the strength required to resist biomechanical stresses throughout the healing period while allowing for tissue ingrowth.

In vivo, the PLLA/TMC mesh and grips nearly completely degrade in 18–24 months and the remaining material resorbs in 36–60 months by hydrolysis to be then metabolised by the body into CO₂ and H₂O.¹¹

The Transorb mesh is intended to reinforce soft weakened tissues of the abdominal wall during hernia repair operated by open surgery.

Study device implantation procedure

Following hernia reduction per the surgeon’s judgement, the Transorb mesh implantation will follow the below instructions:

• The posterior fascia will be closed as a single layer using slowly resorbable monofilament sutures applied in a simple continuous pattern.

• Only a single mesh should be placed during the study procedure.

• The mesh will be placed in the retrorectus or retromuscular space, with or without TAR.

• A minimum of 5 cm mesh overlap over the edges of the fascia incision should be achieved superiorly and inferiorly. When possible, a minimum of 5 cm over the edges of the initial defect should be achieved laterally or at least a mesh coverage of the entire width of the retrorectus/retromuscular compartment is required.

• Mesh fixation may be performed using sutures only following the surgeon’s judgement, depending on the surgical procedure, size of defect and patient conditions.

• After mesh fixation, closure of the anterior fascia of the rectus muscle will be performed using a slowly resorbable monofilament suture with an inter-suture spacing of ≤1 cm and successively applying gentle and uniform pressure on the ventral body wall to allow the grips of the Transorb mesh to engage into the tissue.

• The subcutaneous tissue and skin will be closed according to the surgeon’s preference.

Primary and secondary endpoints

The study primary endpoint will be the clinical hernia recurrence rate within 12 months postoperatively, evaluated by physical examination and confirmed, if necessary, as determined by the study investigator, by site standard of care medical imaging for hernia evaluation.

The secondary endpoints of the study will be:

• Hernia recurrence rate within 1 month, 6 months and 24 months postoperatively, assessed by inperson physical examination (per primary endpoint definition) and within 36 months, 48 months and 60 months postoperatively when suspected during phone call follow-up visits and subsequently assessed by inperson physical examination.

• Hernia recurrence(s) rate resulting in re-operation within 1 month, 6 months, 12 months, 24 months, 36 months, 48 months and 60 months postoperatively.

• Time to hernia recurrence (from the study procedure to clinical hernia recurrence).

• Mesh removal rate related to study device and/or study procedure within 1 month, 6 months, 12 months, 24 months, 36 months, 48 months and 60 months.

• Surgeon satisfaction, assessed by a study-specific questionnaire.

• Surgical site occurrence rate defined as seroma, haematoma, wound dehiscence or surgical site infection that are AEs related to study device and/or study procedure at discharge and within 1 month, 6 months, 12 months, 24 months, 36 months, 48 months and 60 months.

• Surgical site occurrence rate related to study device and/or study procedure and requiring a procedural intervention at discharge and within 1 month, 6 months, 12 months, 24 months, 36 months, 48 months and 60 months.

• Hospital length of stay (from admission to discharge).

• Hernia recurrence rate reported by subjects at 36 months, 48 months and 60 months through the subject hernia questionnaire (VHRI) administered during follow-up visits.

• Change in subject QoL, measured by the AHQ QoL survey at baseline and compared with 1 month, 6 months, 12 months, 24 months, 36 months, 48 months and 60 months.

• Change in subject-reported pain at the hernia site using a Numeric Rating Scale at baseline and compared with pain at the repaired hernia site at 1 month, 6 months, 12 months, 24 months, 36 months, 48 months and 60 months.

An independent clinical event committee (CEC) will conduct an independent adjudication of prespecified AEs for subjects participating in the study. The CEC assessment will be used for analysis.

Statistics

The study sample size is determined adaptively via a Bayesian Goldilocks design.¹² Interim sample size assessments will be conducted throughout to assess the predicted probability of success for the evaluation of the primary endpoint. The first sample size assessment will occur after 100 subjects have been enrolled, with additional assessments occurring with 120 and 140 subjects. Enrolment will end regardless of predicted success after 163 subjects have enrolled. If enrolment is stopped for the primary analysis prior to 163 subjects due to predicted success, supplemental enrolment (up to approximately 163 total subjects) will occur to accommodate long-term secondary endpoints at 5 years post implant. The maximum sample size of 163 was determined via frequentist power analysis where 163 subjects provide at least 90% power to detect a hernia recurrence rate lower than 14.2% assuming a true recurrence rate of 6%. The primary analysis will be conducted in the sample identified via the Goldilocks design and use Bayesian statistical methods. The 12-month hernia recurrence rate, θ, will be evaluated via a beta-binomial model with a non-informative beta (1,1) prior distribution used to calculate the posterior distribution to evaluate the primary hypothesis: Ha:θ§amp;lt;14.2%. The study will be considered a success if at least 97.5% of the posterior distribution is below 14.2%, that is, $P\left(\theta \S amp;lt;0.142|Data\right)\S amp;gt;0.975$.

Analyses of all data will be summarised with standard descriptive summary statistics. Continuous variables will be summarised using number of subjects, mean, SD, median, IQR and ranges. Categorical variables will be summarised using counts and percentages. Credible intervals will be presented at the 95% level unless otherwise stated. Descriptive statistics will be used to summarise secondary study endpoints unless otherwise noted.

All statistical analyses will be performed using Statistical Analysis System for Windows (V.9.4 or higher, SAS Institute, Cary, NC), R Statistical Software (V.4.4.1 or higher; R Core Team 2022) or other widely accepted statistical or graphical software. An independent third party will conduct all interim sample size assessments, and the sponsor will perform the final data analysis.

Subgroup analyses for all endpoints may be performed for the following subgroups:

• Type of hernia (primary and incisional).

• Type of fixation (presence and absence of fixation).

• CDC classification (I and II).

• Use of TAR versus not.

• Number of risk factors (grouping to be based on distribution of risk within enrolled subjects).

Subgroups with too few subjects (such as <10 subjects) may not be reported due to sparse data.

Discussion

Ventral hernia repairs can present significant challenges due to factors such as the complexity of hernia defects, patient comorbidities and the surgical approach used. The use of meshes in ventral hernia repairs is common and considered the gold standard due to their effectiveness in reducing recurrence rates.^{10 13} Synthetic resorbable meshes offer mechanical support to the damaged tissue while gradually resorbing as abdominal wall connective tissue develops.

Here, we present a new synthetic fully resorbable mesh, Transorb mesh, intended for reinforcing weakened abdominal wall soft tissues during open ventral hernia repair. The mesh’s unique design, including ProGrip technology that enhances fixation and potentially reduces the need for additional fixation methods, is designed to offer an alternative to permanent synthetic meshes.

The performance and safety of the Transorb mesh will be evaluated in a single-arm prospective study (RECOVER study, clinicaltrials.gov: NCT06449378), which will enrol patients undergoing open retrorectus ventral hernia repair in clean (CDC class I) and clean-contaminated (CDC class II) surgical fields, in both EU (CDC class I, investigational) and USA (CDC class II, postmarket) centres. The study will include patients presenting with at least one risk factor impairing wound healing. The primary endpoint is to evaluate mesh performance following the critical healing period of 20 weeks, extending through the maturation phase at 1 year. Follow-up evaluations will occur at 1 month, 6 months and annually through 60 months (5 years), offering a comprehensive view of the mesh’s long-term performance and safety.

The single-arm design of the study could represent a limitation for data interpretation due to the absence of an in-study control population. In this regard, randomised control trials are certainly the highest level of evidence; however, when a study does not aim to investigate the intervention of a device compared with another device/no intervention, a single-arm design is sufficient to demonstrate the study objectives. Also, single-arm studies for medical devices are widely accepted for regulatory clearance and market maintenance. Finally, performance goals are commonly used to improve the scientific robustness of single-arm studies and are considered by the FDA as a valid comparison for both effectiveness and safety endpoints.¹⁴

Another limitation might be represented by including in the study groups of patients undergoing different fixation methods and with CDC classifications I and II, as the study was not designed to test differences in these subgroups. Nevertheless, focusing on diverse settings can be crucial to understand the mesh’s application across different clinical scenarios.

In conclusion, the RECOVER study will contribute to providing valuable insights on the use of resorbable meshes in open ventral hernia repair, particularly for patients with risk factors that could impair wound healing. Moreover, the study may identify the Transorb mesh as an alternative option in cases where permanent foreign material is not recommended or for patients who prefer to avoid the use of permanent meshes, offering a new tool to improve patient outcomes in abdominal hernia surgical procedures.

Rosa Paolillo, PhD (Medtronic), provided medical writing assistance under the authors’ direction and based on content and conclusions developed by the authors.

Ethics statements

Patient consent for publication

Not applicable.

Footnote

Contributors All authors provided substantial contribution in designing the work, revising and approving the final manuscript. JSR is the author guarantor.

Funding This work was supported by Medtronic plc company (Trèvoux, France).

Competing interests K.B., M.B. and C.C. are Medtronic employees. The funder didn’t influence this manuscript's writing despite the author's affiliations with the funder. S.J.R., B.R., Y.R., F.B. and M.I.G., as members of the RECOVER study Steering Committee, received funding to provide input on the design of the study

Patient and public involvement Patients and/or the public were not involved in the design, conduct, reporting or dissemination plans of this research.

Provenance and peer review Not commissioned; externally peer reviewed.

References

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