Shoulder Joint Infections with Negative Culture Results: Clinical Characteristics and Treatment Outcomes.

BACKGROUND: The incidence of septic arthritis of the shoulder joint is increasing as the population ages. The prevalence of shoulder infection is also increasing because of the growing use of arthroscopy and expansion of procedures in the shoulder. However, cultures do not always identify all microorganisms, even in symptomatic patients. The incidence of negative cultures ranges from 0% to 25%. Few studies have reported clinical features and treatment outcomes of culture-negative shoulder infections. This cohort study addresses culture-negative shoulder joint infections in nonarthroplasty patients. This study aimed to compare clinical characteristics and treatment outcomes of patients with culture-negative results to those with culture-positive results. Our hypothesis was that culture-negative infections would have more favorable outcomes than culture-positive infections. METHODS: We retrospectively reviewed data of 36 patients (17 culture-negative and 19 culture-positive) with shoulder infections between June 2004 and March 2015. The minimum follow-up duration was 1.2 years (mean, 5 ± 3.8 years; range, 1.2-11 years). We assessed preoperative demographic data and characteristics, laboratory markers, imaging and functional scores, intraoperative findings, and postoperative findings of both groups. RESULTS: Culture-negative patients (17/36, 47.2%) had a significantly lower occurrence of repeated surgical debridement (culture-negative vs. culture-positive: 1.2 ± 0.4 vs. 2.4 ± 1.7, p = 0.002) without osteomyelitis. In the multiple logistic regression analysis, the presence of osteomyelitis [odds ratio (OR) = 9.7, 95% confidence interval (CI): 1.0-91.8, p=0.04)] and the number of surgical debridements (OR = 5.3, 95% CI: 1.3-21.6, p=0.02) were significantly associated with culture-positive infections. CONCLUSIONS: Culture-negative infections without osteomyelitis are less severe than culture-positive infections. Culture-negative infections can be controlled more easily and are not necessarily a negative prognostic factor for shoulder joint infections.

A comparison of stability and clinical outcomes in single-radius versus multi-radius femoral design for total knee arthroplasty.

We compared the intraoperative varus-valgus stability from 0° to 90° of flexion and postoperative clinical outcomes in patients receiving TKA via either a single-radius femoral design (50 TKA, SR group) or multi-radius femoral design (50 TKA, MR group). We measured stabilities at 0°, 30°, 60° and 90° of flexion using a navigation system. The clinical outcomes including HSS scores, WOMAC scores and VAS score during stair climbing were compared after a minimum of 2-year follow-up. The single-radius femoral designs in TKA showed better intra-operative stability at 30° of flexion (7.6 vs. 8.3) compared with the multi-radius femoral design, but not at other angles. However, the clinical outcomes revealed no other significant differences in terms of HSS scores, WOMAC scores and VAS score between two groups.