Browsing by Author "Tseng, Wo-Jan"

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Notch sensitivity jeopardizes titanium locking plate fatigue strength
(2016-12)
Tseng, Wo-Jan
;
Chao, Ching-Kong
;
Wang, Chun-Chin
;
Lin, Jinn
;
生物科技學院
Introduction: Notch sensitivity may compromise titanium-alloy plate fatigue strength. However, no studies providing head-to-head comparisons of stainless-steel or titanium-alloy locking plates exist. Materials and methods: Custom-designed identically structured locking plates were made from stainless steel (F138 and F1314) or titanium alloy. Three screw-hole designs were compared: threaded screw-holes with angle edges (type I); threaded screw-holes with chamfered edges (type II); and non-threaded screw-holes with chamfered edges (type III). The plates\' bending stiffness, bending strength, and fatigue life, were investigated. The stress concentration at the screw threads was assessed using finite element analyses (FEA). Results: The titanium plates had higher bending strength than the F1314 and F138 plates (2.95: 1.56: 1) in static loading tests. For all metals, the type-III plate fatigue life was highest, followed by type-II and type-I. The type-III titanium plates had longer fatigue lives than their F138 counterparts, but the type-I and type-II titanium plates had significantly shorter fatigue lives. All F1314 plate types had longer fatigue lives than the type-III titanium plates. The FEA showed minimal stress difference (0.4%) between types II and III, but the stress for types II and III was lower (11.9% and 12.4%) than that for type I. Conclusions: The screw threads did not cause stress concentration in the locking plates in FEA, but may have jeopardized the fatigue strength, especially in the notch-sensitive titanium plates. Improvement to the locking plate design is necessary. (C) 2016 Elsevier Ltd. All rights reserved.
Outcomes of revision arthroplasty for shoulder periprosthetic joint infection: a three-stage revision protocol
(2019-02-01)
Tseng, Wo-Jan
;
Lansdown, Drew A.
;
Grace, Trevor
;
Zhang, Alan L.
;
Feeley, Brian T.
Background: This study evaluated outcomes after treatment of shoulder periprosthetic joint infection (PJI) with a 3-stage revision protocol consisting of (1) debridement, explantation, and cement spacer placement, followed by parenteral antibiotics; (2) open biopsy and debridement; and (3) reimplantation if cultures were negative. We hypothesized this protocol would eradicate persistent infection while producing excellent functional and subjective outcomes, and there would be no difference in these parameters for patients with shoulder PJI compared with patients with revision for aseptic indications. Methods: We retrospectively analyzed a prospectively collected revision shoulder arthroplasty cohort to identify shoulder PJI patients treated with a 3-stage protocol. Demographics, culture data, range of motion, and patient-reported outcomes were collected. Outcomes for patients with shoulder PJI and revision to RTSA were compared with patients revised to RTSA for noninfectious indications. Significance was defined as P < .05. Results: There were 28 cases of shoulder PJI in 27 patients (age, 66.4 +/- 11.2 years,); of these, 21 shoulders were revised to RTSA, and 7 shoulders were revised to hemiarthroplasty. There was no recurrent infection at a mean 32-month follow-up. One year after surgery, mean forward flexion was 110 degrees +/- 41 degrees and abduction was 106 degrees +/- 42 degrees. Mean final American Shoulder and Elbow Surgeons subjective score was 66.5 +/- 23.3. The 21 shoulders with PJI revised to RTSA had no differences for functional and subjective outcomes compared with revised patients without shoulder PJI. Conclusions: A 3-stage revision protocol for shoulder PJI reliably eradicated infection. Patients with PJI revised to RTSA can have similar outcomes as patients with noninfectious revision to RTSA. (C) 2018 Journal of Shoulder and Elbow Surgery Board of Trustees. All rights reserved.