Prospective cohort study for assessment of cutaneous hypoesthesia around knee replacement surgery

All surgeries will be performed by using conventional TKA surgical technique including a midline skin incision and the medial parapatellar approach under regional/general anaesthesia. The length of the skin incision used will be according to exposure needed. The first assessment will be done at two weeks post operatively after stitch removal. All the demographic details, medical history, implant information (type of knee prosthesis, patella resurfacing, use of intramedullary stem etc.), surgical details (tourniquet time, length of scar, type of anaesthesia, intraoperative complication if any etc.), sensory assessment around knee will be recorded at this point. Postoperative complications (wound-healing problems, such as dehiscence, drainage, or necrosis, and venous thrombosis etc.) will be noted. The patients will be further followed up at 1 month, 2 months and 3 months. For the purpose of sensory assessment, the locations of numbness will be grouped into 4 zones with patella being the center: Zone I: Superomedial quadrant Zone II: Superolateral quadrant 14 Zone III: Inferolateral quadrant Zone IV: Inferomedial quadrant sensory assessment will be done using the blunt pin-prick sensation test which is a simple and reliable method to assess numbness. A blunt pin-prick will be performed every 1 cm vertically and horizontally center being midpoint of patella. Margins and locations of skin numbness will be recorded. An area of skin numbness is defined as an area of at least 1 cm2 . Loss of protective sensations will be assessed by a Semmes-Weinstein monofilament size 5.07/10g, which will be applied to the skin with the knee in full extension. The patients will be asked to map out the area of hypoesthesia around knee with skin marker pen. After marking up of the area by the patient a calibrated digital picture of the area marked with knee joint will be taken. Area of hypoesthesia will be calculated by using calibrated picture of the knee in full extension using Image J software18 (US, National Institutes of Health, Bethesda, MD). The FJS-12 (Forgotten joint score) Questionnaire will be filled by asking specific questions from the patients and scores obtained will be used for analysis of the same and its correlation with cutaneous hypoesthesia at final follow up with minimum follow up of 3 months.