According to recent findings, the pilonidal sinus is an acquired condition, and a previously discussed congenital cause now seems unlikely.
The following factors are considered predisposing in its development: male gender, obesity, heavy hair growth in the natal cleft, poor hygiene, sedentary activities, a deep gluteal cleft, positive family history.
Hair plays a particularly significant role in this context: F. Stelzner demonstrated as early as the 1980s that hairs, fixed on small barbs, penetrate the skin. Another indication that hair plays a crucial role is the fact that pilonidal sinus is unknown in China, as Chinese people do not have hair in the natal cleft.
In its latest updated form from 2014, the guidelines of the German Society for Coloproctology recommend open surgery as the treatment method of choice.
The abscess is initially widely unroofed to allow effective drainage. The definitive treatment of the pilonidal sinus is then performed electively in one of the following two ways:
- Excision with secondary wound healing or
- Excision with primary wound closure (only in the infection-free stage!) → after excision, the wound is primarily closed with sutures, possibly with reconstructive plastic surgery.
The local or systemic administration of antibiotics is to be rejected, as they do not achieve definitive healing of the sinus. The injection of phenol solution is obsolete due to its high toxicity and possible absorption of phenol.
There is no spontaneous healing. An asymptomatic pilonidal sinus persists for life but can also progress to the acute (abscessing) form or the chronic stage. After prolonged existence, malignant transformation is theoretically possible but only rarely described in the literature.
After excision, secondary wound healing is not significantly more effective than primary wound healing. The recurrence rate is lower with open therapy (significant in the current Cochrane analysis).
The excision of the pilonidal sinus should be complete. Typically, the excision of the granulation tissue is performed close to the sacral fascia. However, there is no clear evidence in the literature that the periosteum should be involved. In contrast, it must be assumed that excision of the periosteum with denudation of the sacrum increases postoperative pain and significantly worsens healing.
To ensure complete excision, marking the foxhole-like inflammatory tissue with toluidine blue is recommended. Doll and colleagues showed that the use of toluidine blue has a significant impact on the recurrence rate.
A primary median wound closure after excision of a pilonidal sinus is associated with high postoperative morbidity and recurrence rate. The frequency of wound healing disorders reaches a rate of 30% or more in the case of primary median wound closure.
For open wound treatment, a healing time of over 3 months is not unusual.
Open wound treatment is not an optimal alternative due to the prolonged postoperative treatment phase and socioeconomic burden (multiple recurrences are also not optimal). Surgical methods that avoid the formation of a median wound and lead to flattening of the gluteal cleft seem sensible and could lead to better short- and long-term results. Further studies are needed here.
A systemic preoperative antibiotic prophylaxis does not seem to affect the wound healing process. This was demonstrated in the prospective randomized study by Sondenaa. Other reports confirmed this observation.
The depilation is theoretically supposed to reduce the recurrence rate. However, it has long been known that mechanical hair removal using blade shaving offers no advantage. Stirnemann and Blasimann showed as early as 1983 that the recurrence rate cannot be reduced by mechanical shaving. A Bundeswehr cohort study from 2009 showed the same effect, indicating that mechanical shaving even favored recurrence development (Petersen 2009). Whether hair removal without creating additional broken hair (laser epilation) could become a promising treatment option for recurrence prevention is the subject of further investigations and cannot currently be generally recommended.