The infrapatellar branch of the saphenous nerve is often injured during total knee arthroplasty (TKA), leading to numbness in its distribution distal to the incision. This is illustrated in a patient who suffered full-thickness burns to the lateral aspect of the knee from a hot water bottle. However, the proportion of patients who are informed of this phenomenon (as well as the effect of informing the patient of numbness) has not previously been studied according to the authors' knowledge. The aim of this study was to establish the proportion of patients with whom postoperative numbness was discussed during the consent procedure and whether this discussion was documented.
A total of 73 patients (103 TKAs) agreed to take part in this study between 16 May and 9 July 2011. Patients were asked about their recollection of numbness being mentioned prior to the procedure as well as whether they experienced postoperative numbness. Statistical analysis was performed using SPSS®.
Subjective numbness was noted in 27% of the patients in this study. The prevalence of numbness decreased with time. Patients whose consent process included a discussion of numbness were 3.3 times more likely to report numbness after TKA (p=0.003).
Patient education regarding postoperative numbness increases the patient's awareness of any insensate skin that may develop. Numbness after TKA does improve with time but does not resolve completely. It is therefore recommended by the authors that numbness is discussed preoperatively with the patient and that this discussion is documented.