Purpose: Unicompartmental replacement for medial compartment arthrosis of the knee has become popular with eligible patients because of the shortened recovery time, decreased tissue damage and easier future revision. Contemporary multimodal anesthesia has added the potential to safely perform this as outpatient surgery reducing inpatient bed burden. We describe our initial pilot experience with this approach.

Method: The first 25 patients who fulfilled the criteria developed underwent same day surgery for unicompart-mental arthroplasty for medial (19) or lateral (3) compartment replacement with either the Oxford knee (20) or the Uniglide (2). All patients were treated with an indwelling femoral nerve catheter supplied by Ropivacaine through a constant release pump (Stryker) which was discontinued at 48 hours. Home care support was made available in first 72 hours by way of RN and physiotherapy visits and mandatory use of walker or crutches for the first 48 hours.

Results: Patients in this cohort were universally very satisfied with the model of postop care as described and particularly pleased to avoid a hospital stay. Eighty percent of those who were offered this model chose it. The use of narcotic oral medication was consistently about 50% less than that observed to similar inpatients treated without catheter, and eight patients had complete opioid sparing experience. There were no complications related to the catheter, in particular serious falls or longer term neurologic sequelae. The clinical results were very good and equal to those who were in patients.

Conclusion: Outpatient unicompartmental replacement can be performed safely recognizing the decreased surgical trauma and pain stimuli associated with UKR and a relatively younger and healthier cohort screened for this alternative. These patients are amongst the most satisfied with their perioperative course and all would do the same again if given the chance. Other models of analgesia could be considered, though the catheter does seem to have a large opioid sparing effect that likely contributed to patient well being and satisfaction.