The current meta-analysis is to compare between intra-operative difficulties and post-operative complications in elective repair of large incisional hernias using on-lay mesh and sub-lay mesh. We have comprehensively searched and assessed the published literature regarding this topic. We have focused solely on the data regarding the comparison between on-lay mesh and sub-lay mesh using the random-effects model.
Repair of incisional hernia is regarded as one of the most challenging general surgical procedure, due to the high recurrence rate and post-operative morbidity. Open mesh repair (onlay and sublay technique) is proved to be superior to suture repair. However due to the presence of mesh this technique is not without morbidity such as wound complication like seroma formation and infection. 21 In our study ten trials included comparison between onlay and sublay mesh in large insicional hernia repair were selected from electronic databases.
As regards recurrence, ten included studies described recurrence using onlay versus sublay with follow-up at least 3 months, Demetrashvili et al. stated 4 patients suffered from recurrence in 72 months follow-up using onlay method and 2 patients using sublay method, Ahmed r et al. stated zero patients suffered from recurrence in 72 months follow-up using onlay method and also zero patients using sublay method, Somooro et al. stated 2 patients suffered from recurrence in 24 months follow-up using onlay method and zero patients using sublay method and Saeed et al. stated 3 patients suffered from recurrence in 24 months follow-up using onlay method and zero patients using sublay method, Barış Sevinç et al. stated zero patients suffered from recurrence in 46 months follow-up using onlay method and one patients using sublay method, Badawy et al. stated three patients suffered from recurrence in 24 months follow-up using onlay method and one patient using sublay method,
In addition to,Leithy et al. stated 2 patients suffered from recurrence in 12 months follow-up using onlay method and zero patient using sublay method, Deen et al. stated one patient suffered from recurrence in 12 months follow-up using onlay method and one patient using sublay method S. Natarajan et al. stated one patient suffered from recurrence in 6 months follow-up using onlay method and zero patient using sublay method and A. Iljin et al. stated zero patient suffered from recurrence in 72 months follow-up using onlay method and zero patient using sublay method (P = 0.94, I2 = 0%) and OR 2.228, 95% CI 0.9, 5.378 and no statistically significance.
Regarding infection, ten included studies described infection using onlay versus sublay with follow-up at least 3 months, Demetrashvili et al. stated 39 patients in 72 months follow-up using onlay method and 17 patients using sublay method, Ahmed et al. stated 6 patients in 72 months follow-up using onlay method and also 3 patients using sublay method, Somooro et al. stated 18 patients in 24 months follow-up using onlay method and 2 patients using sublay method and Saeed et al. stated 2 patients in 24 months follow-up using onlay method and 4 patients using sublay method, Barış Sevinç et al. stated 2 patients in 46 months follow-up using onlay method and 2 patients using sublay method Badawy et al. stated 7 patients in 24 months follow-up using onlay method and 2 patient using sublay method. In addition to, Leithy et al. stated 6 patients in 12 months follow-up using onlay method and 1 patient using sublay method, Deen et al. stated 3 patients in 12 months follow-up using onlay method and one patient using sublay method, S. Natarajan et al. stated 2 patients in 6 months follow-up using onlay method and 1 patient using sublay method and
A. Iljin et al. stated 2 patients in 72 months follow-up using onlay method and 2 patients using sublay method (P = 0.296, I2 = 16%) and OR 2.726, 95% CI 1.579, 4.705 and no statistically significance.
In addition to, Seroma was assessed in nine included studies comparing between onlay verus sublay.
Demetrashvili et al. stated 32 patients in 72 months follow-up using onlay method and 13 patients using sublay method, Ahmed et al. stated 13 patients in 72 months follow-up using onlay method and also 3 patients using sublay method, Somooro et al. stated 24 patients in 24 months follow-up using onlay method and 4 patients using sublay method andSaeed et al. stated 3 patients in 24 months follow-up using onlay method and zero patient using sublay method, Barış Sevinç et al. stated 7 patients in 46 months follow-up using onlay method and 1 patient using sublay method.
In addition to, Leithy et al. stated 6 patients in 12 months follow-up using onlay method and 1 patient using sublay method, Deen et al. stated 3 patients in 12 months follow-up using onlay method and one patient using sublay method, S. Natarajan et al. stated 5 patients in 6 months follow-up using onlay method and zero patient using sublay method and A. Iljin et al. stated 212 patients in 72 months follow-up using onlay method and zero patient using sublay method (P = 0.917, I2 = 0%) and OR 4.962, 95% CI 3.038, 8.107 and no statistically significance.
While, hematoma was assessed in four included studies comparing between onlay verus sublay.
Demetrashvili et al. stated 2 patients using onlay method and 2 patients using sublay method,Saeed et al. stated 2 patients using onlay method and 5 patients using sublay method, Barış Sevinç et al. stated 3 patients using onlay method and 1 patient using sublay method.
In addition to, A. Iljin et al. stated zero patient using onlay method and zero patient using sublay method (P = 0.534, I2 = 0%) and OR 0.860, 95% CI 0.291, 2.541 and no statistically significance.
Flap necrosis was assessed in four included studies comparing between onlay verus sublay.
Somooro et al. stated 2 patients in 24 months follow-up using onlay method and zero patient using sublay method and Badawy et al. stated 4 patients in 24 months follow-up using onlay method and 2 patients using sublay method.
In addition to, Leithy et al. stated 1 patient in 12 months follow-up using onlay method and zero patient using sublay method, A. Iljin et al. stated zero patient in 72 months follow-up using onlay method and zero patient using sublay method (P = 0.923, I2 = 0%) and OR 2.415, 95% CI 0.661, 8.822and no statistically significance.
Regarding operative time, eight included studies described operative time using onlay versus sublay, Demetrashvili et al. stated 124 minutes mean time with standard deviation 34 using onlay mesh and 155 minutes with standard deviation 42 using sublay mesh, Ahmed et al. stated 110 minutes mean time with standard deviation 30 using onlay mesh and 80 minutes with standard deviation 32 using sublay mesh, Somooro et al. stated 120 minutes mean time with standard deviation 26 using onlay mesh and 100 minutes with standard deviation 30 using sublay mesh and, Barış Sevinç et al. stated 56 minutes mean time with standard deviation 7 using onlay mesh and 73 minutes with standard deviation 17 using sublay mesh, Deen et al. stated 83 minutes mean time with standard deviation 10 using onlay mesh and 89 minutes with standard deviation 7 using sublay mesh and A. Iljin et al. stated 105 minutes mean time with standard deviation 30 using onlay mesh and 180 minutes with standard deviation 30 using sublay mesh (P = 0.001, I2 = 95.1%) and OR 12.022, 95% CI -31,460, 5.616 and there is statistically significance.
Regarding hospital stay, seven included studies described hospital stay using onlay versus sublay, Demetrashvili et al. stated 5.5 mean time with standard deviation 2.5 using onlay mesh and 5 mean with standard deviation 2.5 using sublay mesh, Ahmed et al. stated 8 days mean time with standard deviation 4 using onlay mesh and 4 mean time with standard deviation 2 using sublay mesh, Saeed et al. stated 2 days mean time with standard deviation 0.8 using onlay mesh and 3.9 mean time with standard deviation 1.9 using sublay mesh and, Barış Sevinç et al. stated 3.3 mean time with standard deviation 1.9 using onlay mesh and 3.5 mean with standard deviation 2.56 using sublay mesh, Badawy et al. stated 4.3 mean time with standard deviation 3.7 using onlay mesh and 3.6 mean with standard deviation 2 using sublay mesh and Deen et al. stated 4.6 mean time with standard deviation 0.3 using onlay mesh and 2.6 mean time with standard deviation 0.7 using sublay mesh and A. Iljin et al. stated 5 mean time with standard deviation 3 using onlay mesh and 8.5 mean time with standard deviation 3 using sublay mesh (P = 0.001, I2 = 96.03%) and OR 2.726, 95% CI -1.250, 1.759 with statistically significance.
Limitations
This meta- analysis is limited by the level of evidence and qualities of the studies analyzed. Although most studies did report similar objective criteria to measure treatment outcomes, many studies employed different grading systems. Only small number of studies performed power analyses. Moreover, it was difficult to reach a greater sample size and we did not have complete homogeneity with the method of scintigraphy because the studies were done in different institutions. Selection bias was also present, as many of these studies were retrospective reviews.