Reduction in narcotic use after primary total knee arthroplasty and association with patient pain relief and satisfaction.

We examined the prevalence of narcotic use before and after total knee arthroplasty (TKA) and its association with post-TKA pain relief and satisfaction. Data on 6364 primary, unilateral TKA patients in a national registry were analyzed. Before TKA, 24% of patients were prescribed one form of narcotic. Of these, 14% reported continued narcotic use at 12 months after TKA, whereas the majority discontinued use. Only 3% of patients who did not use narcotics before TKA had a narcotics prescription at 12 months. Patients who used narcotics before TKA were more likely to have a narcotic prescription at 12 months post-TKA, reported greater pain at 12 months, and were more likely to be dissatisfied with TKA outcome. These findings have implications for patient pre-TKA counseling.

Open Reduction Internal Fixation of Posterior Malleolus Fractures and Iatrogenic Injuries: A Cadaveric Study.

Open reduction internal fixation of posterior malleolus fractures from a posterior approach is gaining popularity. One concern that has not been studied is the risk of iatrogenic injury to anatomical structures on the anterior ankle. The purpose of this study is to determine the proximity of these anterior structures with relation to K-wires advanced through the anterior cortex. A total of 10 cadaver ankles were utilized in the study. A posterolateral approach to the ankle was used. K-wires were advanced at varying levels above the articular surface, and then, the proximity of the wires to the following structures was determined: the neurovascular bundle, tibialis anterior (TA), and extensor hallucis longus. Overall, the structure most in danger of being injured was the TA (P < .001). This tendon was injured by 52% of all K-wires. These data suggest that K-wires should be advanced under direct fluoroscopic visualization to minimize the risk of iatrogenic injury. LEVELS OF EVIDENCE: Level IV.

Detailed structural analysis of amyloidogenic wild-type transthyretin using a novel purification strategy and mass spectrometry.

Wild-type transthyretin (TTR), normally a soluble plasma-circulating protein, can be amyloidogenic, i.e., form tissue-deposited fibrillar material in the extracellular matrix of various organs throughout the body. Senile systemic amyloidosis (SSA) is one such pathology and features TTR-containing amyloid deposits that are found primarily in the heart. The cause for this transition from soluble to insoluble protein in SSA is yet to be determined as specific structural features that might favor TTR fibrillogenesis have not yet been identified. The precise characterization of ex vivo fibril deposits might provide insight, but structural analyses of TTR from amyloid deposits have been hindered thus far by the lack of purification strategies that overcome the insolubility of the tissue-derived protein without degrading it. Consequently, the true biochemical nature of deposited TTR remains in question. In this study, we provide detailed analyses of both the soluble (serum) and deposited (tissue) forms of TTR from cases of SSA. In the serum, a distribution of mixed disulfides, specifically S-sulfonated and S-cysteinylated forms of TTR, as well as the unmodified protein were identified. The relative levels of the three TTR species in the SSA group were comparable to amounts present in sera from age-matched control groups. For characterization of the amyloid deposited TTR, we investigated cardiac tissue samples obtained from three separate cases of SSA. We report a novel chromatographic purification strategy performed under nonreducing conditions (to maintain cysteine disulfide status) and the use of this procedure in conjunction with detailed mass spectrometric analysis of TTR from the amyloid deposits. A series of C-terminal TTR fragments with N-termini ranging from amino acids 46 to 55 were identified. We also determined that the deposits in all samples contained Cys10 disulfide-linkedhomodimers composed of full-length TTR monomers. This last finding suggests an important role for Cys10 conjugation in the transition from soluble TTR to the pathological amyloid fibril.