The effect of polyethylene thickness on revision rates of contemporary cruciate retaining knee replacements. A registry analysis.

BACKGROUND: An attribute that may influence knee replacement survivorship is tibial polyethylene (PE) insert thickness. Previous studies have suggested thin polyethylene made from ultra-high molecular weight polyethylene (UHMWPE) leads to higher rates of revision surgery. This study aimed to determine if modern polyethylene thickness is associated with altered survivorship of primary total knee arthroplasty (TKA) procedures. METHODS: A retrospective analysis of data from Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR) was done on well performing total knee arthroplasty prostheses used in Australia from 1999-2018. Six of the best performing minimally stabilized prostheses were examined and categorized into three PE thickness subgroups: A (≤10 mm), B (11-14 mm) and C (≥15 mm). There were 185,539 TKA procedures, of which 64.3% (n = 119,382) were ≤ 10 mm, 33.5% (n = 62,173) 11-14 mm, and 2.2% (n = 3984) ≥ 15 mm. Differences in revision rates were analysed for all causes, including loosening, wear, and instability. RESULTS: At 14 years, respective cumulative point revision (CPR) was A: 4.8, B: 4.2 and C: 6.0. The thickest polyethylene group (≥15 mm) had a higher rate of revision for any reason compared to both 11-14 mm and ≤ 10 mm groups. When non-XLPE was analysed the ≤ 10 mm group had higher rates of revision compared to the 11-14 mm group, but this difference was not seen with XLPE. CONCLUSION: Higher rates of revision were seen overall in the thicker PE group (≥15 mm). This group also had higher rates of revision for loosening, instability, and infection. The use of a thicker insert may be a sign of surgical complexity, but is associated with increased revision.

Resident Versus Attending Surgeons in Achieving and Maintaining Fracture Reduction in Pediatric Distal Radius Fractures.

BACKGROUND: Distal third forearm fractures are one of the most common orthopaedic injuries in the pediatric population with a reported risk of redisplacement in the range of up to a third following initial reduction. The aims of this study were to determine whether fracture redisplacement and adequacy of cast molding were associated with surgeon seniority in the treatment of displaced pediatric distal third radius fractures that required manipulation under anesthesia. METHODS: This study prospectively randomized 143 pediatric patients presenting to a tertiary referral hospital with a fractured distal radius into 2 groups. We compared the surgeon seniority (resident vs. attending surgeon) with the cast index (CI) and amount of displacement/angulation postreduction. RESULTS: Our results showed no significant difference in CI according to level of experience between resident and attending surgeon (P=0.14). There was also no difference in redisplacement for fracture types relative to seniority. Median redisplacement for resident and attending, respectively, for type Arbeitsgemeinschaft für Osteosynthesefragen (AO) 23E was 6% (range, 0% to 42%) versus 6% (range, 0% to 41%) P=0.98. For type AO 23M reangulation was 4 degrees (range, 0 to 29 degrees) versus 5 degrees (range, 0 to 18 degrees) P=0.97, respectively. CONCLUSIONS: Our results indicate that the level of seniority does not influence the CI or redisplacement/angulation of fractures after closed reduction. Residents appear well trained in cast application. LEVEL OF EVIDENCE: Level I-randomized-controlled trial.

Irinotecan causes severe small intestinal damage, as well as colonic damage, in the rat with implanted breast cancer.

BACKGROUND AND AIMS: Irinotecan (CPT-11) is a chemotherapeutic drug for cancer that causes severe diarrhea by an uncertain mechanism. The aim of the present study was to investigate the time-course of apoptosis and whole intestinal damage after irinotecan to further elucidate the mechanism behind the diarrhea. METHODS: Groups of breast cancer-bearing dark agouti (DA) rats were treated with 100, 150 or 200 mg/kg doses of irinotecan or vehicle control daily for two days, and killed at 6, 24, 72 or 96 h after treatment. Apoptosis and morphometry were examined in both the small and large intestines. Histopathology and goblet cell numbers were recorded. Data were analyzed using the Peritz' F-test. RESULTS: Irinotecan increased apoptosis and caused villous atrophy and crypt hypoplasia in the small intestine, and increased apoptosis, crypt hypoplasia, crypt dilation and mucus secretion in the large intestine. Irinotecan at 100 and 150 mg/kg caused crypt hypoplasia at 6 and 24 h, with rebound hyperplasia at 72 and 96 h. At 200 mg/kg, irinotecan caused a more pronounced crypt hypoplasia earlier and all animals died by 96 h. Apoptosis peaked at 6 h and remained elevated over the remainder of the time-points. This was not dose-dependent. Irinotecan at all doses altered colonic, but not jejunal, goblet cells. Irinotecan increased colonic mucus secretion. CONCLUSIONS: We conclude that irinotecan causes diarrhea by inducing apoptosis and hypoproliferation in both the small and large intestines, and causes colonic damage with changes in goblet cells and mucin secretion.