Catastrophic failure of a low profile metal-backed glenoid component after total shoulder arthroplasty.

CONTEXT: The longevity of the glenoid component in total shoulder arthroplasty (TSA) continues to be problematic. All polyethylene glenoid components have been most widely used, but loosening rates with time and the need for revision has resulted in high-profile metal-backed components with the potential for a more stable prosthesis bone interface and liner exchange. High revision rates in the high profile metal backed designs led us to evaluate a low profile metal backed component. AIMS: To examine the rate and mode of failure of a TSA in a single surgeon consecutive series that has been identified by the Australian National Joint Replacement Registry to have a higher than anticipated rate of revision. MATERIALS AND METHODS: This is a single surgeon retrospective consecutive series of 51 arthroplasties undertaken in 50 patients (18 males and 32 females) with an average age of 70.4 ears (range 51-90) and mean follow-up of 5.5 years (range 3.7-8.1). RESULTS: We observed a very high (29%) rate of revision of the metal-backed glenoid components in this series. The primary mode of failure was glenoid baseplate nonintegration which with a well-fixed central cage screw led to bone resorption and implant breakage or disassembly. CONCLUSION: Analysis of the mode of failure of implants identified by robust registries is essential for the development of new prostheses and the pursuit of prosthesis longevity. This low profile metal backed prosthesis has been withdrawn, but without a published mechanism of failure. We feel that any prosthesis withdrawal should be accompanied by appropriate published mechanisms to prevent future component design errors based on similar design problems.

Prospective evaluation of treatment of open fractures: effect of time to irrigation and debridement.

IMPORTANCE: The standard practice of irrigation and debridement (I&D) of open fractures within 6 hours of injury remains controversial. OBJECTIVE: To prospectively evaluate the effect of the time from injury to the initial I&D on infectious complications. DESIGN, SETTING, AND PARTICIPANTS: A total of 315 patients who were admitted to a level 1 trauma center with open extremity fractures from September 22, 2008, through June 21, 2011, were enrolled in a prospective observational study and followed up for 1 year after discharge (mean [SD] age, 33.9 [16.3] years; 79% were male; and 78.4% were due to blunt trauma). Demographics, mechanism of injury, time to I&D, operative intervention, and incidence of local infectious complications were documented. Patients were stratified into 4 groups based on the time of I&D (<6 hours, 7-12 hours, 13-18 hours, and 19-24 hours after injury). Univariate and multivariable analysis were used to determine the effect of time to I&D on outcomes. MAIN OUTCOMES AND MEASURES: Development of local infectious complications at early (<30 days) or late (>30 days and <1 year) intervals from admission. RESULTS: The most frequently injured site was the lower extremity (70.2%), and 47.9% of all injuries were Gustilo classification type III. There was no difference in fracture location, degree of contamination, or antibiotic use between groups. All patients underwent I&D within 24 hours. Overall, 14 patients (4.4%) developed early wound infections, while 10 (3.2%) developed late wound infections (after 30 days). The infection rate was not statistically different on univariate (<6 hours, 4.7%; 7-12 hours, 7.5%; 13-18 hours, 3.1%; and 19-24 hours, 3.6%; P = .65) or multivariable analysis (<6-hour group [reference], P = .65; 7- to 12-hour group adjusted odds ratio [AOR] [95% CI], 2.1 [0.4-10.2], P = .37; 13- to 18-hour group AOR [95% CI], 0.8 [0.1-4.5], P = .81; 19- to 24-hour group AOR [95% CI], 1.1 [0.2-6.2], P = .90). Time to I&D did not affect the rate of nonunion, hardware failure, length of stay, or mortality. CONCLUSIONS AND RELEVANCE: In this prospective analysis, time to I&D did not affect the development of local infectious complications provided it was performed within 24 hours of arrival.

In vitro biomechanical testing of anterior cruciate ligament reconstruction: traditional versus physiologically relevant load analysis.

Various anterior cruciate ligament (ACL) graft-fixation devices exist. In this in vitro study a comparison of biomechanical characteristics of the cross-pin and button type fixation devices under practical rehabilitation loads was done. Forty bovine knees and hoof extensor tendons were harvested. After disarticulation, the femoral end of an ACL was prepared with either fixation, using the extensor tendon as graft. The mechanical test was either a single load to failure or load to failure after cycling loads. Twenty specimens were loaded to failure at a rate of 1mm/s, remaining specimens were cycled between 50 and 250 N for 1000 cycles then failure tested in a similar manner. Results show that both forms of fixation are able to withstand loads that exceed those observed in performing functional activities. Activity-specific stiffness (loads comparable to walking, jogging and stair descent) was lower than linear stiffness for both endobutton and cross-pin, without prior cycling. After cycling, activity-specific stiffness increased to linear stiffness values for the cross-pin for all activities. Thus, suggesting that the cross-pin provides a more rigid fixation after initial implantation over a wider range of activities, which would theoretically permit a more aggressive rehabilitation protocol and possibly an earlier return to regular activity. In contrast, activity-specific stiffness increased above linear stiffness values for the endobutton only under heavier loads (jogging and stair descent). Dynamic stiffness was higher and displacement lower for cross-pin throughout the cycle test. These results indicate, in ACL reconstruction, that graft complex stiffness should be considered at relevant loads only.