Background: Pyogenic flexor tenosynovitis is a closed space infection involving the digital flexor tendon sheaths of the upper extremity that can cause considerable morbidity. The purpose of the present report is to describe the various risk factors leading to poor outcomes and to recommend a clinical classification system for this condition.

Methods: We studied seventy-five patients with pyogenic flexor tenosynovitis over a six-year period. The amputation rate and total active motion were used as outcomes measures. The clinical factors influencing outcomes were identified and analyzed.

Results: The five risk factors associated with poor outcomes were (1) an age of more than forty-three years, (2) the presence of diabetes mellitus, peripheral vascular disease, or renal failure, (3) the presence of subcutaneous purulence, (4) digital ischemia, and (5) polymicrobial infection. On the basis of the clinical findings and outcomes, three distinct groups of patients could be identified, each with a progressively worse outcome. Patients in Group I had no subcutaneous purulence or digital ischemia; these patients had the best prognosis, with no amputations and a mean 80% return of total active motion. Patients in Group II demonstrated the presence of subcutaneous purulence but no ischemic changes; these patients had an amputation rate of 8% and a mean 72% recovery of total active motion. Patients in Group III had both extensive subcutaneous purulence and ischemic changes; these patients had the worst prognosis, with an amputation rate of 59% and a mean 49% return of total active motion.

Conclusions: We propose a three-tier clinical classification system that can aid in prognosis and guidance in the treatment of pyogenic flexor tenosynovitis of the upper extremity.