**Figure 5.**

*The steps of open lateral internal sphincterotomy. a) the circumferential incision is made in the intersphincteric groove, b) deepening the dissection with the help of retractors, c) the division of the internal sphincter muscle.*

*Sphincterotomy is the Gold-Standard Treatment of Chronic Anal Fissure: But How Should it be… DOI: http://dx.doi.org/10.5772/intechopen.104109*

internal sphincter by moving the blade medially. The expected rate of division is 1/3 to 1/2 of the internal sphincter muscle.

Many authors have reported that the closed technique is effective and safe with a similar cure and fewer complication rates [51, 52]. In contrast, Wiley et al. has demonstrated similar incontinence rates between open and closed techniques, although overall, 6.8% of incontinence rates have been detected during a follow-up of 52 weeks [53]. Based on these contradicted results, it has been suggested that rather than an open or closed approach, the extent of sphincterotomy may influence the rates of incontinence and healing [54].

#### *5.1.3 Radial vs. circumferential incision in lateral internal sphincterotomy*

According to the surgeons' experience and preference, open sphincterotomy can be performed with radial or circumferential incisions. Ersoz et al. has reported that the circumferential incision is associated with shorter healing time and fewer itching sensations than radial incisions [55]. Similar results about reduced time for wound healing with circumferential incision have also been proven by Kang et al. [56]. Both authors have suggested that the fecal material creates an outward force vector resulting in dilatation of the anal canal associated with more dehiscence in the radial incision.

#### *5.1.4 Extent of sphincterotomy*

Another attempt to decrease incontinence rates has been the proposal of performing sphincterotomy up to the height of the fissure apex instead of to the dentate line [57]. This technique initially showed high healing rates with significantly lower incontinence rates [58]. However, long-term follow-up results have demonstrated higher rates of treatment failure and slower effects on healing [59]. In another study evaluating the recurrence/persistence of fissure and incontinence rates, endoanal ultrasonography was performed after percutaneous and open sphincterotomy [60]. It has been confirmed that open and complete sphincterotomy is associated with lower recurrence rates but increased incontinence, while partial and percutaneous sphincterotomy has resulted in persistence and recurrence of the fissure. These results have supported that sphincterotomy should be complete but shorter, whether percutaneous or open sphincterotomy is performed.

Furthermore, the extent of sphincterotomy and its association with incontinence have been investigated between female patients and the control group by performing three-dimensional anal ultrasonography [61]. The extent of sphincterotomy has been directly related to incontinence, and it should be less than 25% of the total sphincter length (less than 1 cm in females) (**Figure 6**). Interestingly, this study has also demonstrated a significant decrease in anal resting pressure, whereas the maximum squeeze pressure has remained similar to preoperative measurements. A recent study has also reported supporting findings for dividing the internal sphincter by about 20% in female patients [62].

#### *5.1.5 Ultramodified internal sphincterotomy*

Sungurtekin et al. has described a new technique called ultra-modified internal sphincterotomy, which involves an incision made in the base of the posterior fissure, identification of the internal and external sphincter under direct vision, division of previously measured 1 cm of internal sphincter bundle [63].

**Figure 6.**

*Measurement of sphincterotomy***.** *a) Sphincterotomy is measured as 1 cm from the anal verge, b) the distance of sphincterotomy to the dentate line is shown as 2 cm.*

They have reported the results of this technique in comparison to the closed sphincterotomy. The anal resting pressures have decreased in both study groups; however, the decline in pressures has lasted for 24 months in closed technique and is attributed to iatrogenic damage in the internal anal sphincter. Moreover, the patient satisfaction and recovery rates have been higher in the ultramodified sphincterotomy group.
