summary Felons are subcutaneous abscesses of the fingertip pulp. Diagnosis is made clinically by assessing for tenderness, erythema and fluctuance of the fingertip pulp. Treatment is usually I&D and IV antibiotics. Epidemiology Incidence accounts for 15-20% of hand infections Anatomic location most commonly occurs in the thumb or index finger Etiology Pathophysiology mechanism of injury penetrating injury blood glucose needlestick splinters local spread may spread from paronychia no history of injury in 50% of patients may result from bacterial contamination of the fat pad through the eccrine sweat glands pathophysiology overview swelling and pressure within micro-compartments, leading to "compartment syndromes" of the pulp progression inflammation and cellulitis leads to local vascular congetsion if left untreated, tissue necrosis and abscess formation leads to increased microvascular impairment increasing pressure can eventually lead to "compartment syndrome" and subsequent ischemia affects the blood supply to the diaphysis more than the blood supply to the skin, causing bone necrosis and sequestration before spontaneous decompression through the skin organisms Staphylococcus aureus most common organism gram negative organisms found in immunosuppressed patients Eikenella corrodens found in diabetics who bite their nails Anatomy Fingertip pulp closed sac connective tissue framework separated by fibrous vertical septae running from periosteum of the distal phalanx to the epidermis provides structural support stabilizes the pulp during pinch and grasp contains eccrine sweat glands that open onto the epidermis Blood supply digital arteries run parallel to the distal phalanx gives off a nutrient branch to the epiphysis before entering the pulp space Presentation Symptoms severe throbbing pain Physical exam swelling does not extend proximal to DIP flexion crease unless flexor tendon sheath or joint is involved tenderness Imaging Radiographs indications only indicated if history of trauma to rule out fracture or foreign body MRI indications not indicated Studies Serum Labs not indicated Differential Herpetic Whitlow Paronychia Glomus Tumor Mucous cyst Psoriasis Diagnosis Clinical diagnosis is made with careful history and physical examination Treatment Nonoperative oral antibiotics and observation indications early felon (no drainable abscess) Operative bedside I&D and IV antibiotics indications most cases Techniques Bedside I&D anesthesia digital block approach keep incision distal to DIP crease to prevent DIP flexion crease contracture and prevent extension into flexor sheath mid-lateral approach indicated for deep felons with no foreign body and no drainage incision on ulnar side for digits 2-4 and radial side for thumb and digit 5 (non-pressure bearing side of digit) volar longitudinal approach most direct access indicated for superficial felons, foreign body penetration, or visible drainage incisions to avoid fish-mouth incision risk of unstable finger pulp or vascular compromise double longitudinal or transverse incision risk of injury to digital nerve and artery debridement avoid violating flexor sheath or DIP joint to prevent spread into these spaces break up septa to decompress infection and prevent compartment syndrome of fingertip obtain gram stain and culture hold antibiotics until culture obtained place gauze wick postoperative routine dressing changes Complications Finger tip compartment syndrome Flexor tenosynovitis Osteomyelitis Digital tip necrosis Prognosis If left untreated, can lead to sequestration of the diaphysis of the distal phalanx pyogenic arthritis of the DIP joint flexor tenosynovitis from proximal extension