Introduction: Besides having various health consequences for the patients, post-operative wound infections following orthopaedic surgery increase health costs, often markedly. Optimal estimates of such costs require accurate incidence data over a prolonged period.

The test group: Five hundreds and eighty consecutive patients undergoing orthopaedic surgery during the period May 1st 1998 to December 31st 1999 were studied. They underwent either of the following procedures: total primary hip replacement; total primary knee replacement; operations for trochanter-major fracture (using Hip Compression Screw); ankle fractures.

Methods: The basic cost of the 580 operations was estimated from the aggregated costs of diagnosed related groups (DRG)-costs, applying only major codes. Patients who had to be re-admitted later because of wound infections during 1999 were studied and their secondary, wound-infection related costs was estimated from the aggregated DRG-costs during these hospitalisations.

Results: A total of 47 of the 580 patients had a diagnosis of a post-operative wound infection, 14 were deep and 33 were superficial infections; 15 were readmitted for their infections. The additional days of hospitalisation for these re-admissions totaled 270 hospital days with an aggregated cost of 230.000.- Euro, compared to 3.000.000.- Euro for all 580 operations (fig. l shows graphically expenses caused by post operative wound infections as a fraction of the total cost).

Discussion: Additional hospital costs related to postoperative wound infections amounted to 7% of the total hospital costs over a period of 20 months. Additional expenses not counted are those related to insurance compensations, sick leave compensations, expenses related to doctor visits and visits to out patient departments besides expenses related to additional nursing at home. Added to strict economic calculations are less easily calculable, short or prolonged reductions in quality of life. It is emphasized that post-operative wound infections after orthopaedic surgery represent a major cause for additional health expenses and reductions in quality of life.