Experience with a new prosthetic anal sphincter in three coloproctological centres
© Goos et al.; licensee BioMed Central Ltd. 2013
Received: 12 December 2012
Accepted: 27 September 2013
Published: 8 October 2013
Fecal incontinence is a common and severely disabling disorder. For patients with severe fecal incontinence, surgery may prove to be the only adequate treatment option.
This study reports on 43 patients that were treated with a prosthetic sphincter system between 2005 and 2009 in three coloproctological centres. Main Outcome Measures: complications, anal pressures before and after surgery, fecal continence score.
The new artificial sphincter system significantly improves continence but leads to some complications in clinical practice. After implantation of the device, continence improved significantly (Keller & Jostarndt continence score 2.6 to 14.3 (P < 0.01)). With the band activated, resting pressure improved significantly as compared to baseline (10.7 mmHg vs. 66.1 mm Hg, P < 0.01). The same holds for anal sphincter squeeze pressure (32.2 mmHg versus 85.9 mm Hg, P < 0.01). Complications occurred in 21 patients (48.8%): 10 surgical and 13 technical. Two patients were affected by both technical and surgical problems. The median time of the occurrence was 3 months postop. In five patients difficulties arose within the first postoperative month leading to explantation of the device in three patients. 90% of complications occurred in the first year.
The soft anal band of AMI (AAS), a new artificial anal sphincter, improves severe anal incontinence, but it must be regarded as a last treatment option to avoid a stoma.
KeywordsFecal incontinence Prosthetic sphincter Treatment option
In adult females, the most frequent cause of fecal incontinence is obstetric trauma .
Fecal incontinence is usually an acquired disorder. A small percentage of cases are congenital disorders, such as imperforate anus, rectal agenesis, cloacal defects, myelomeningoceles, and meningoceles .
Conservative measures, such as dietary and lifestyle modifications and pelvic floor exercises are effective in managing mild symptoms and can also be implemented following surgical procedures [2, 7, 8]. However, surgery is often the only effective treatment for severe incontinence.
In refractory disease, an artificial sphincter should only be considered as a last resort as an alternative to a stoma. Anal sphincter prostheses are strictly mechanical devices and were first implanted to manage urinary incontinence in 1973 . Fourteen years later, the Lancet reported on a modified “scott-sphincter” to treat fecal incontinence . The main purpose of artificial sphincters is to mimic the external anal sphincter’s (EAS) ability to control the passage of faeces through the anus. They do so with the help of circular, flexible and refillable cuffs. Currently, two systems are being implanted: the Acticon Neosphincter® (Artificial Bowel Sphincter (ABS)) produced by American Medical Instruments (A.M.S., USA) and the Soft Anal Band System produced by Agency for Medical Innovations (A.M.I., Austria).
At three different coloproctological centres, 43 patients with Grade III fecal incontinence (FI) received a Soft Anal Band System (AAS; Agency for Medical Innovation (AMI), Feldkirch (Austria), CE Body Number (0297) ID: 170530317; Reg. No. 066924 MR2).
Causes of fecal incontinence
inborne / acquired sphincter defect
birth trauma (6x), state after previous surgery (9×): sphincter or pelvic floor repair, rectopexy, hemorrhoidectomy, etc.
sequelae after rectal surgery:
rectum resection (7×), abdomino-perineal pull-through
neuroborreliosis, herniated disc, spina bifida, incomplete spinal cord injury, encephalitis disseminata, lesion of pudendal nerve
pelvic / pelvic floor trauma (road accident)
scleroderma (2×), irradiation of prostate cancer
Keller & Jostarndt continence score (KJCS)
> 3 per day
2-3 per day
0 - 1 per day
perception of urgency
regularly none or too late
always just in time or certain
discrimination (gaseous, liquid, solid)
36 – 31 points
30 – 24
11 - 0
The KJC scores were calculated before the operation and at the time of activation of the device. Anal resting and squeeze pressures (RP / SP) were measured using a water-filled pressure sensor that was connected to a handheld device designed to display and record values (Sphinctometer: STM-0169-SM, smProMedico, Aachen, Germany).
Measurements were recorded before surgery and at the time of system activation. Readings were taken for the filled (active) and relaxed (inactive) anal band.
Statistical analysis was performed with STATA® 11.0 statistical packages.
Soft anal band system
Currently, two systems are being implanted: the Acticon Neosphincter® (Artificial Bowel Sphincter (ABS)) produced by American Medical Instruments (A.M.S., USA) and the Soft Anal Band System produced by Agency for Medical Innovations (A.M.I., Austria).
The Artificial Anal Sphincter (AAS) from A.M.I. is similarly designed to the one of AMS (ABS). The AAS is implanted subcutaneously and consists of four parts, which are all connected by silicone tubes: 1.) the Soft Anal Band made of silicone (available in three sizes, plus two extension parts, also available in two different sizes), 2.) a silicone-bonded valve to control the fill-liquid of the system, 3.) a manually operated silicone balloon (activator) to move the fill-liquid into the band to close the sphincter, and 4.) a titanium port with anti-kink protection for individual adjustment of the fill volume. When pressure is applied to the balloon by the patient, the fill-liquid moves from the balloon to the band and continence is achieved. To open the sphincter for defecation, the patient presses on the valve, the fill-liquid moves from the band to the balloon leaving the sphincter open. The connection between the valve and the subcutaneous safe puncture port (semi-automatic pump), which is placed lateral to the iliac crest, permits accurate adjustment of the amount of liquid inside the system (Figure 1).
The size of the anal band was either estimated or measured with a tape measure. After positioning the anal band, the connecting tube to the valve was placed subcutaneously from the perianal region to the lower abdominal wall. The perianal wounds were closed with sutures in double layer technique or sealed with histoacrylic glue.
The tube from the band connects on one side of the valve. The activator and the port are also connected to the valve. Once in situ, the system was deflated and then filled with a defined mixture of 18 ml distilled water and radio-opaque solution. The system was now checked for function and leakage. Anal band function was tested manometrically and digitally and then left in the open position for 5–6 weeks to allow for healing.
Valve, activator and port were fixed with PDS 2/0 to the underlying fascia. After five to six weeks, patients were instructed on how to activate the Soft Anal Band System.
This observational study was approved by the ethics committee of the university hospital of Freiburg (No. 437/129).
Anal pressure values changed significantly after the operation. On average 10.7 mmHg (SD8.3) was measured for resting pressure, and 32.2 mmHg (SD21.6) for squeeze pressure.
After surgery, continence improved significantly (KJCS 2.6 (SD2.3) to 14.3 (SD2.7), P < 0.01).
Anal resting and squeezing pressures before and after surgery
Pressures at the time of activation
resting pressure (SD) [mmHg]
squeezing pressure (SD) [mmHg]
Revisions of the device were necessary due to failure of the valve (8×) and failure of the anal band (2 ×). In all cases the affected components were replaced. Two patients had to be treated repeatedly due to valve failures.
In 4 patients revisions where necessary due to development of a fibrotic capsule (1 ×); weight gain (1× - > transposition of the device); pain (1×); bleeding after activation of the device occurred once under oral anticoagulation. In all cases the affected implant site was surgically revised, the implants were retained.
Two patients were unable to operate the valve by themselves. Close relatives had to help in handling the valves.
In discussing the results, one must bear in mind that prosthetic sphincters are the last therapeutic option in the treatment of severe fecal incontinence before a stoma is created. A stoma is for many patients a source of significant psychological distress. In order to avoid a stoma, these patients are willing to live with an artificial implant, which may only improve their symptoms slightly. In the study present 43 patients were treated with a new artificial bowel sphincter and prospectively examined over 32 month on average. The AAS elevates anal pressure values significantly from 11 to 66 mmHg for the resting pressure and 32 to 85 mmHg for the squeezing pressure respectively. Although many patients are still significantly incontinent, the condition is less severe. KJC-Scores improved from 3 to 14, which corresponds to an FI grade II.
The modest prospects of treatment must be given to the patient.
The study is of descriptive nature. The results reflect the experiences with this new artificial bowel sphincter device. The data were collected uniformly and prospectively. Although the results are compared with published data for the well-studied Neosphincter, general statements can not be made about an advantage or inferiority of the AAS.
Innovative sphincter prosthesis has now become available in the form of the soft anal band system (AAS). Infections and penetration rates are comparatively low. Handling the valve is the main product-related difficulty, whereby the product manual does provide adequate instructions. The AAS improves incontinence, but it must be regarded as a last surgical treatment option to avoid a stoma. Preliminary results show a considerable complication rate with wound infections in four and band perforation / penetration in one patient. Explantation of the device was necessary in a total of 9 out of 43 patients.
Technical problems relating to valve handling or system failure should be addressed in the design of the improved second generation Soft Anal Band System (AAS). The manufacturer released a new version of the valve in 2011.
Keller & Jostarndt continence score
Artificial Anal Sphincter (Soft Anal Band System ®, A.M.I)
Artificial bowel sphincter (Acticon Neosphincter ®, A.M.S)
Agency for medical innovations (Austria)
American medical instruments (USA)
External anal sphincter
The article processing charge was funded by the German Research Foundation (DFG) and the Albert Ludwigs University Freiburg in the funding programme Open Access Publishing.
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