Q: How can I tell if hip or knee post-surgical site redness is infectious? 

A: Post-acute care for hip and knee replacements has changed significantly over the decades. Today, younger patients with minimal risk factors are sent home after surgery. But patients who have complicated hospital courses or comorbidities are admitted to sub-acute rehabilitation before going home. 

Arthroplasty requires skin incision and a new joint placement. Skin erythema may be a normal process of healing post surgically. So how can you differentiate normal healing from suture hypersensitivities or evolving infection of the skin or the deeper tissues? 

Early detection of any infection is the first step to avoid complications. Yet overtreatment with antibiotics may cause more harm than good due to antibiotic resistance. A few signs and symptoms are critical. 

Suture hypersensitivities occur more commonly as raised redness or bumps around suture sites with progressive redness spreading out. Normal post-surgical erythema may be diffuse redness with mild swelling and expected pain with movements.

Often, evolving infection may present with post-surgical erythema that progresses to surgical site infection. This may have worsening redness with swelling, disproportionate pain with movement, or systemic coindicators such as fever or tachycardia. Caution is advised for patients with renal, cardiac, and neurological diseases who are immunocompromised. 

Daily inspection of the wound is crucial. Checking blood for ESR and CRP may assist with monitoring the progression of infection, though they will be elevated post operatively. Blood testing does not replace timely and appropriate assessment of the patient. 

Assessing daily symptoms of pain with and without movements, monitoring other comorbidities, rehabilitation and connecting with other interdisciplinary team members play a significant role in a safe discharge.