Cutaneous sensory loss following primary total knee arthroplasty. A two years follow-up study

We examined 32 patients for skin flap numbness around their scars after primary total knee arthroplasty (TKA). All 32 patients were reviewed six weeks following surgery and two years thereafter. The aims of our study were to determine the natural history of cutaneous sensory loss, to identify the relationship with scar length and scar location, as well as the relationship between the size of the numb area and the severity of numbness and its recovery pattern. We also studied the relationship between numbness and other factors such as tourniquet time, lateral release and patella resurfacing. Twenty-six patients (81%) had lateral skin flap numbness; the other six patients (19%) had normal skin sensation around the scar. The size of the numb area was large in 19 patients (73%) out of 26. Our findings suggest more severe sensory loss is associated with larger numb area. Patients with a smaller numb area had less severe sensory loss. More laterally placed incisions were having better sensation (p = 0.00435). Patella resurfacing (p = 0.5) and lateral retinacular release (p = 0.10) were not significantly associated with the skin numbness. Fifty percent of our patients fully recovered from skin numbness at the end of two years. Patients with a small numb area had a more favourable outcome compared to those with a larger numb area. We conclude that permanent cutaneous sensory loss is not a universal occurrence following primary TKA; however a significant number of patients can be affected by this complication. All the patients should be warned about cutaneous numbness before the surgery.