Long-term recurrence and complication rates after incisional hernia repair with the open onlay technique

Background Incisional hernia after abdominal surgery is a well-known complication. Controversy still exists with respect to the choice of hernia repair technique. The objective of this study was to evaluate the long-term recurrence rate as well as surgical complications in a consecutive group of patients undergoing open repair using an onlay mesh technique. Methods Consecutive patients undergoing open incisional hernia repair with onlay-technique between 01/05/1995 and 01/09/2007 at a single institution were included in the study. For follow-up patients were contacted by telephone, and answered a questionnaire containing questions related to the primary operation, the hernia and general risk factors. Patients were examined by a consultant surgeon in the outpatient clinic or in the patient's home if there was suspicion of an incisional hernia recurrence. Results The study included 56 patients with 100% follow-up. The median follow-up was 35 months (range 4–151). Recurrent incisional hernia was found in 8 of 56 patients (15%, 95% CI: 6–24). The overall complication rate was 13% (95% CI, 4–22). All complications were minor and needed no hospital admission. Conclusion This study with a long follow-up showed low recurrence and complication rates in patients undergoing incisional hernia repair with the open onlay technique.


Background
Incisional hernia is a well-known complication after abdominal surgery, with incidence rates of approximately 3% and 15% after laparoscopic and open surgery, respectively [1]. Hernias are associated with reduced quality of life and high socioeconomic costs [2]. The treatment of incisional hernias have changed radically over the last decade, however controversy still exists concerning mesh type [3], mesh positioning [4] and operation method, with laparoscopic repair as an increasingly preferred alternative to open surgery [5]. In the present study we evaluated the long-term recurrence and complication rates after incisional hernia repair with open onlay technique in a consecutive series of patients.

Methods
The study included consecutive patients who underwent open hernia repair with onlay technique between May 1995 and September 2007 (see figure 1). All hernias disregarding size were operated by the same technique which included closure of the hernia defect with non-absorbable sutures (typically Prolene 2-0) followed by an onlay polypropylene mesh (figure 1). Thus, the mesh was placed superficial to the external fascia also using non-absorbable sutures. Repair operations were carried out by four senior surgeons at a single institution.
Each patient was contacted by telephone and underwent a structured interview. The interview contained questions concerning previous operations for incisional hernia, suspected or diagnosed incisional hernia, and other types of hernia (e.g. inguinal). All patients were interviewed between January 2008 and August 2008. A recurrence was "suspected" if the patient was not sure if he/she had a hernia or not. A hernia was "diagnosed" if the primary care physician or a surgical specialist had examined the patient and established the diagnosis. In the interview, hernias were described regarding reducibility, aggravating factors, cosmetic inconvenience, and mental stress related to the hernia. Wound length, localisation of the incision, wound complications and type of treatment were registered as well as patient related risk factors such as co-morbidity, use of systemic corticosteroids, and use of alcohol or tobacco. If the patient had a suspected hernia or a diagnosed hernia he was examined by a single consultant surgeon in the outpatient clinic or in the patient's home.
Data are reported as frequencies (CI -95% confidence intervals) and median (range) unless stated otherwise. For analysis of categorical and continuous data, Fishers exact test and Mann Whitney's test were used. P < 0.05 was con-sidered statistically significant. The study was approved by the local ethics committee.

Results
A total of 92 patients had an incisional hernia repair with open onlay technique during the inclusion period. However, 36 patients could not participate in the study for various reasons ( Figure 2). Thus, the study included 56 patients with 100% follow-up.
Demographics (age, gender, weight, alcohol, tobacco), risk factors (prostate hypertrophy, diabetes mellitus, chronic obstructive pulmonary disease, the number of self reported co-morbidities), the length of the follow-up period, and hernia related data are presented in table 1. All demographic data are at the time of follow-up.
The median observation time was 35 months (range 4-151). In our follow-up we found by clinical examination that 4 of the 56 patients had developed a hernia. Another 4 patients had undergone a repair operation for a recurrent incisional hernia in the follow-up period before the interview making the total number of recurrences 8 of 56 patients (15%, 95% CI: 6-24).
An overall complication rate of 13% (95% CI, 4-22) was found. Three patients were treated for seroma or haematoma with evacuation of fluid. One patient was treated for wound infection with antibiotics. One patient had a secondary closure of the wound due to exudation, and one patient had a minor complication, but was unable to remember the specific treatment at follow up. None of these patients had a recurrent hernia on follow-up. One patient was diagnosed with seroma/hematoma but received no treatment, however, this patient later developed a hernia. None of these complications required hospital admission, thus there were no serious complications after the hernia repair.

Discussion
In this study we have shown a low long-term recurrence rate of 15% and an overall rate of non-serious complications of 13% after open hernia repair using the onlay mesh technique in a single institution.
The surgical treatment of incisional hernia has changed rapidly during the last decade with the increasing use of mesh technique and the introduction of laparoscopy. However, many questions concerning mesh type, mesh positioning, fixation method and operation type still remain unanswered [3,4]. Patients with incisional hernia are a heterogeneous population with patient-specific comorbidity and innate differences (e.g. collagen formation quality) [6]. This makes the choice of technique most suitable for each patient even more difficult.
Schematic drawing of the mesh position Figure 1 Schematic drawing of the mesh position. The hernia defect was routinely sutured and the onlay mesh was used as a reinforcement of the suture line. Flow chart of the study cohort Figure 2 Flow chart of the study cohort.

Oper ated patient = 92
Patients lost to follow-up = 11 Denied par ticipation = 1 Recur r ent her nia + Minor complication = 1 Minor complication = 6 Recur r ent her nia = 7 Eligible patients = 56 No r ecur r ent her nia or complication = 42 Died befor e follow-up = 16 Lived in another countr y = 8 Our study included 56 consecutive patients in a single institution with a median follow-up period of 35 months (range 4-151). In accordance with previous studies we chose to combine a structured interview with a clinical examination [1,[10][11][12][13]. This method proved to be effective with a clinical examination of all eligible patients suspected of hernia. Our study group showed no significant differences with respect to distribution of known risk factor between patients with or without recurrent hernia.
The onlay technique is a simple and effective repair operation with a short learning period for the surgeon. For open incisional hernia repair the choice between inlay, onlay and sublay technique is often based on tradition and the individual surgeon's expertise rather than scientific evidence. It has been routine to perform all incisional hernias by the onlay technique at the institution involved in the present study, and we therefore don't have any patients who had been operated by other open techniques. Our study shows that the onlay technique seems to be safe in terms of complication and recurrence rates for the patient. In addition this technique requires little tissue dissection with an easy access to the hernia repair.  None of the demographic data or risk factors were statistically significant between groups.
The laparoscopic approach is generally associated with at longer learning curve.
The present study has several limitations. It is retrospective and has a limited number of patients. Twenty operated patients did not participate, and 16 patients had died before follow-up. This is a consequence of the long follow-up period. In addition many of the patients lived outside the country and could not be contacted to participate in the follow-up. In a recent systematic review by Müller-Riemenschneider et al., evaluating the long term prognosis, a trend towards lower recurrence rates, shorter hospital stay, lower complication rates, and lower pain scores after laparoscopic approach was found, but with a higher frequency of intestinal perforation [5]. However, all identified studies suffered from significant methological limitations such as different baseline characteristics among patients, short follow-up periods or small patient numbers, and longterm results after laparoscopic repair still remains unknown. Our results, although from a single institution, show very low and clinical insignificant complication rates and a very low long-term recurrence rate making the open onlay mesh technique a serious alternative to laparoscopic repair in selected patients. Future large scale randomized studies should clarify indications for laparoscopic versus open onlay technique.

Conclusion
We found low long term recurrence and complication rates after open hernia repair with onlay mesh technique. These results require confirmation by randomized clinical trials.