Pilonidal disease affects young adults after puberty and is unusual after the age of 40. The condition is painful and unpleasant, typically affecting overweight patients in their second and third decades, who are dark haired and often have poor personal hygiene. Treatment is sought either because of pain, persistent offensive discharge, or the development of major secondary infection, such as a pilonidal abscess.

Sacrococcygeal pilonidal disease was found in 365 of 31497 men (1.1 per cent) and in 24 of 21367 women (0.11 per cent) in a survey of Minnesota college students. A higher proportion of females attend for treatment giving a treatment ratio of four males to every female. The condition is more common in Caucasians than in Asians or Africans.

Pilonidal sinus is an acquired disease due to obstruction of hair follicles in the natal cleft, often associated with ingrowth of hair. Subcutaneous hair acts as a foreign body, initiating a reaction which is often complicated by varying degrees of infection. Ingrowth is enhanced by the rolling or sucking action of the obese buttock, or by prolonged sitting and vibration, as illustrated by the epidemic of pilonidal disease seen in American military personnel during the Second World War (jeep drivers' disease).

The sinus is pit lined with epithelium and sometimes containing hair. It is centrally placed and 4 to 8 cm cephalad to the anus. When the pilosebaceous follicle has been obstructed a cavity lined with granulation tissue forms, with the subsequent development of secondary tracks; these may rupture lateral to the midline creating secondary openings. These tracks may become complex, and as the diseases progress treatment becomes increasingly difficult.

The ideal treatment leads to rapid recovery with a short hospital stay, a low possibility of recurrence, and minimal pain. Infection is the main cause of treatment failure.

This can be defined as a central sinus, with a small cavity and minimal secondary tracks where the openings are not far from the midline.

The sinus, associated granulation tissue, and secondary tracks should be excised. Whether the patient is prone with the buttocks strapped apart, or in the left lateral position, is a matter of preference. It is advisable to administer a preoperative bolus of a broad spectrum antibiotic, active against aerobic and anaerobic bacteria: cefuroxime 1.5 g IV and metronidazole 1 g IV would be appropriate for most patients. Having excised the area and secured haemostasis, the wound is closed with three or four deeply placed mattress sutures of 1 nylon, which are introduced about 1 cm away from the skin edges, and pass right through the fat to the level of the sacral fascia. More superficially placed sutures of 2/0 or 3/0 nylon can be added to ‘tidy up’ the wound and to ensure that the skin edges are accurately approximated.

Tension sutures and pressure dressings cause wound ischaemia and hinder healing, and are not indicated. If there is concern that the excised area will ooze, causing an accumulation of blood and serum beneath the skin flaps which could prejudice healing, a fine bore suction drain should be inserted. This is removed when drainage is minimal, usually by the second or third postoperative day. The superficial ‘fine’ sutures are removed after 1 week and the deeper sutures after 10 days. If the wound becomes obviously infected during this period, the sutures are removed early, and the opened wound packed with antiseptic impregnated gauze.

Traditional treatment involved excision of the affected area and daily packing of the open wound. Time to healing averaged over 40 days, with considerable patient discomfort and prolonged nursing time. Primary closure in selected cases gives healing in over 90 per cent of patients in 2 weeks. In those patients in whom the wound has to be reopened, time to healing is not likely to be in excess of those treated traditionally with excision and an open wound. Covering the operation with prophylactic antibiotics, or even a full course of seven days treatment may improve the results, but this is not proven.

Lord's procedure offers the prospect of treating complex sinus tracks on an outpatient basis. Treatment involves excision of the follicle opening and the passage of small brushes down the tracks on a weekly basis, removes granulations and encourages free drainage, permitting healing to take place. Other treatments have included the injection of phenol solution into the tracks to stimulate fibrosis. In expert hands this treatment produces healing in an average of 42 days, but it has never been popular. This may be because of the need for regular outpatient visits and the careful supervision required.

Radical excision of the area is not indicated: this takes months to heal and is very painful. The long-term recurrence rate is disappointingly high.

Complex tracks can be laid open and packed individually. Alternatively a skin flap can be used to cover the defect, keeping the scar from the midline and creating a flattened natal cleft. The greatest experience of this is provided by the ‘advancing’ flap operation proposed by Karydakis. This operation gave primary healing and long-term cure in the vast majority of a very large series of Greek army personnel treated for pilonidal sinus. Whether this would be reproduced by others is questionable. More complex flap operations have been described, but there is no evidence to suggest that these give better results.

Preventing further ingrowth of hair whilst the wound remains immature is important, and the patient is advised to keep the area scrupulously clean and free of hair by the use of depilating agents or by shaving.

Drainage of the abscess under general anaesthetic rapidly relieves pain. All infected granulation tissue and tracks should be excised at the same time and the wound packed with antiseptic impregnated ribbon gauze. The pack is changed daily until healing is complete. The aim is the creation of a saucer shaped wound, which should heal from its base without the development of epithelial bridges to prevent proper packing. Most patients will be allowed home on the third postoperative day, with further supervision of packing on an outpatient basis. Healing can be achieved in about 60 per cent of patients treated in this way in 10 weeks. The remainder will either take much longer to be cured or will be left with a pilonidal sinus; 40 to 60 per cent of these will need further treatment.

Primary closure after drainage of the abscess and local installation of antibiotic gel has given excellent results in some hands, and over 80 per cent of wounds so treated have been reported to undergo primary healing with an extremely low rate of recurrence. However there is no convincing evidence that this is the correct method of treatment.

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