Comparison of the functional outcomes after treatment of periprosthetic hip fractures with femoral stem loosening: Locking plate fixation with or without femoral stem revision.

INTRODUCTION: Periprosthetic fractures have become one of the main reasons for revision of total hip arthroplasty, with the treatment strategy guided by the Vancouver and SOFCOT classification systems. The main objective of this work was to compare the functional outcomes and mortality rate in patients who suffered a periprosthetic hip fracture with femoral stem loosening and who were treated either by internal fixation with locking plate only, or in combination with revision of the existing femoral stem with a cemented stem. The secondary objective was to compare the blood loss, procedure duration, length of hospital stay, living arrangements, time to weight bearing and major complications between these two treatment strategies. The starting hypothesis was that there is no difference in the functional outcomes between these two groups. MATERIALS AND METHODS: This was a single center, retrospective study of patients treated between 2013 and 2019. Thirty-six patients (54%) underwent femoral stem revision (FSR group) and 31 patients (46%) were treated by locking plate fixation only (ORIF group). In this population, 19 of the patients had been residing at a nursing home before the surgical treatment: 12 (33%) in the FSR group and 7 (23%) in the ORIF group (p=0.33). The mean preoperative Parker score was 7.03 (± 1.48) in the FSR group versus 5.19 (± 1.92) in the ORIF group. The functional outcomes at the final review were evaluated using the Parker score, HHS (Harris Hip score), WOMAC (Western Ontario and McMaster Arthritis Index) and Oxford score. Fracture healing was determined on radiographs centered over the hip joint with the entire femur visible on AP and lateral views. All patients were reviewed at a minimum of 1 year for clinical and radiological assessments. RESULTS: At a mean follow-up of 28 months [12-85], the Oxford score was 40.4 (± 10.6) in the FSR group versus 37.1 (± 13.5) in the ORIF group (p=0.34), WOMAC of 45.5 (± 26.9) versus 50.5 (± 32.4) (p=0.56), and HHS of 62.7 (± 25.5) versus 60.3 (± 28.6) (p=0.79). The Parker score at the final assessment was 5.14 (± 1.96) in the FSR group versus 4.64 (± 2.17) in the ORIF group (p=0.33). In the FSR group, 10 patients were at a nursing home (34%), 6 of whom were not there initially, versus 6 in the ORIF group (43%), 5 of whom were not there initially (p=0.59). The mean operating time was 152±41.4 minutes (minimum: 85; maximum: 254) in the FSR group versus 89.2 (± 44.1) minutes (minimum: 39; maximum: 280) in the ORIF group (p<0.001). Resumption of full weight bearing occurred at 6 weeks in 21 patients (58%) in the FSR group versus 14 patients (47%) in the ORIF group (p=0.023). There were 5 major complications (14%) in the FSR group versus 7 (23%) in the ORIF group (p=0.35). Among the reviewed patients, the union rate was 86% on the latest radiographs in the FSR group versus 78% in the ORIF group. DISCUSSION: There was no statistically significant difference between groups in the various functional scores, confirming our study hypothesis. Internal fixation with a locking plate appears to be an acceptable solution for treating periprosthetic hip fractures in which the femoral stem has loosened. LEVEL OF EVIDENCE: III, comparative retrospective study.

Fluorescent nanoparticles as selective Cu(II) sensors.

Latex nanoparticles functionalized with cyclam (1,4,8,11-tetraazacyclotetradecane), a copper chelator, have been doped with a fluorescent dye (BODIPY derivative: 4,4-difluoro-8-(2',4',6'-trimethyl)phenyl-2,6-diethyl-1,3,5,7-tetramethyl-4-bora-3a,4a-diaza-s-indacene). The bulky, hydrophobic fluorophore dissolves within the nanoparticles' polymer core up to a concentration of about 88.4 micromol g(-1). At this concentration the fluorescence yield is about 0.80. Adding Cu2+ ions to the solution decreases the fluorescence because of the energy transfer between the dye and the violet copper cyclam complexes. The response is fast: 90% of the quenching occurs within 1 s. The Cu2+ detection threshold is of 1 nanomolar. No interferences were observed with zinc and nickel ions.

Triisobutylaluminium and diisobutylaluminium hydride as molecular scalpels: the regioselective stripping of perbenzylated sugars and cyclodextrins.

To explain the remarkable regioselective de-O-benzylating properties of diisobutylaluminium hydride (DIBAL-H) and triisobutylaluminium (TIBAL) towards polybenzylated sugars or cyclodextrins, we propose a plausible mechanistic rationale critically involving the kinetic formation of a product-generating 2:1 Al-benzylated sugar complex. For the reaction to occur, one pair of adjacent oxygen atoms should first be able to form a chelation complex with the first equivalent of aluminium reagent, either a highly fluxional complex with tetracoordinate aluminium species or a pentacoordinate one. The second equivalent then induces the regioselectivity of the de-O-alkylation by coordinating preferentially to one of the oxygen atoms of the selected pair.