Survivorship, complications, and outcomes following distal femoral replacement for neoplastic indications.

Background: Distal femoral replacements (DFRs) are excellent treatment options for limb salvage procedures in patients who have bone loss secondary to neoplasm. Multiple studies report adequate survivorship and complication rates following DFR implantation, primarily for non-neoplastic indications. However, current literature regarding neoplasm-specific reports is often limited by sample size, survivorship, and patient reported outcome measurements. Therefore, we sought to examine patients who received a DFR for a neoplastic indication at multiple tertiary academic centers. Specific outcomes analyzed included: (1) revision-free survival, (2) medical/surgical complications, and (3) Knee Injury and Osteoarthritis Outcome Score for Joint Replacement (KOOS JR). Methods: All patients who underwent a DFR for a neoplastic indication were retrospectively reviewed. A total of 29 knees were included for various neoplastic indications. Outcomes of interest included: post-operative thromboses, pneumonia, dislocations, periprosthetic joint infections (PJIs), aseptic loosening, osteolysis, emergency department visits, inpatient readmissions, and revision surgeries. Patient-reported outcome measure (PROM) collected included: Knee Injury and Osteoarthritis Outcome Score for Joint Replacement (KOOS JR). Results: Revision-free survivorship was 72.4 % at 23 months with radiographic follow-up. PJI was the most common post-operative complication, affecting 3 knees (10.3 %). The mean number of emergency department visits and inpatient readmissions averaged less than one per patient (0.63 and 0.41, respectively). KOOS JR scores improved markedly among from baseline to final follow-up (44.1-57.8). Conclusion: The use of DFR led to satisfactory medium-term clinical outcomes with an acceptable complication rate for this challenging group of patients. The marked improvement in patient satisfaction for this patient population gives a promising outlook for patients who will undergo this procedure in the future and can guide patient-provider regarding surgical expectations.

Comparison of single-stage and delayed gastrocnemius flap procedures for soft-tissue defects of the knee and proximal tibia.

PURPOSE: Gastrocnemius flaps provide reliable reconstructive solutions to soft-tissue loss of the knee and proximal tibia following orthopedic procedures. While this technique has been used and studied, little is known about its prophylactic application. Single-stage and delayed approaches were compared with respect to the timing of débridement, complications, and relationship between microorganisms and complications. METHODS: Gastrocnemius flaps for soft-tissue defects of the knee joint were retrospectively reviewed. Success of the flap procedure was defined as a healed soft-tissue envelope, no evidence of infection, a good blood supply to the flap, and adherence of the flap to its bed. Independent sample t test was used to compare the corresponding parameters (level of statistical significance was 0.05). RESULTS: Of 43 flaps (43 patients), 18 were performed during a single-stage procedure along with the orthopedic procedure and 25 were delayed. Success of the single-stage (100%) and delayed flaps (88%) was not significantly different (p = 0.083). Complication rate did not differ significantly for single-stage (11%) and delayed flaps (24%) (p = 0.272). We were unable to establish a relationship between complications and microorganisms. CONCLUSION: Results indicate both approaches are reliable. Single-stage gastrocnemius flaps may eliminate the need for a second surgery. LEVEL OF EVIDENCE: Level III (Therapeutic, Retrospective cohort).

Using Ligand-Accelerated Catalysis to Repurpose Fluorogenic Reactions for Platinum or Copper.

The development of a fluorescent probe for a specific metal has required exquisite design, synthesis, and optimization of fluorogenic molecules endowed with chelating moieties with heteroatoms. These probes are generally chelation- or reactivity-based. Catalysis-based fluorescent probes have the potential to be more sensitive; however, catalytic methods with a biocompatible fluorescence turn-on switch are rare. Here, we have exploited ligand-accelerated metal catalysis to repurpose known fluorescent probes for different metals, a new approach in probe development. We used the cleavage of allylic and propargylic ethers as platforms that were previously designed for palladium. After a single experiment that combinatorially examined >800 reactions with two variables (metal and ligand) for each ether, we discovered a platinum- or copper-selective method with the ligand effect of specific phosphines. Both metal-ligand systems were previously unknown and afforded strong signals owing to catalytic turnover. The fluorometric technologies were applied to geological, pharmaceutical, serum, and live cell samples and were used to discover that platinum accumulates in lysosomes in cisplatin-resistant cells in a manner that appears to be independent of copper distribution. The use of ligand-accelerated catalysis may present a new blueprint for engineering metal selectivity in probe development.