Is There Harm in Debridement, Antibiotics, and Implant Retention Versus Two-Stage Revision in the Treatment of Periprosthetic Knee Infection? Experiences Within a Large US Health Care System.

BACKGROUND: When faced with a periprosthetic joint infection (PJI) following total knee arthroplasty, the treating surgeon must determine whether 2-stage revision or "liner exchange," aka debridement, antibiotics, exchange of the modular polyethylene liner, and retention of fixed implants (DAIR), offers the best balance of infection eradication versus treatment morbidity. We sought to determine septic re-revision risk following DAIR compared to initial 2-stage revision. METHODS: We conducted a cohort study using data from Kaiser Permanente's total joint replacement registry. Primary total knee arthroplasty patients who went on to have a PJI treated by DAIR or 2-stage revision were included (2005-2018). Propensity score-weighted Cox regression was used to evaluate risk for septic re-revision. RESULTS: In total, 1,410 PJIs were included, 1,000 (70.9%) treated with DAIR. Applying propensity score weights, patients undergoing DAIR had a higher risk for septic re-revision compared to initial 2-stage procedures (hazard ratio 3.09, 95% CI 2.22-4.42). Of DAIR procedures, 150 failed (15%) and went on to subsequent 2-stage revision (DAIR-F). When compared to patients undergoing an initial 2-stage revision, we failed to observe a difference in septic re-revision risk following DAIR-F (hazard ratio 1.11, 95% CI 0.58-2.12). CONCLUSION: Although DAIR had a higher risk of septic re-revision, we failed to observe a difference in risk following DAIR-F when compared to those who initially underwent 2-stage revision. Functional outcome, patient, and organism factors are important to consider when discussing PJI management options. LEVEL OF EVIDENCE: Level III.

Cruciate-retaining TKA is an option in patients with prior patellectomy.

BACKGROUND: The recommendation for using posterior-stabilized (PS) implants in patellectomy patients undergoing total knee arthroplasty (TKA) is based on older case series with heterogeneous patient populations. The use of cruciate-retaining implants in these patients has not been evaluated with more contemporary implant designs. QUESTIONS/PURPOSES: The purpose of this study was to evaluate the survivorship and functional outcomes (Knee Society score, presence of an extensor lag, and range of motion) of cruciate-retaining (CR) TKA in patients with prior patellectomy. METHODS: Between 1986 and 2012, we performed 27 CR TKAs in 25 patients after patellectomy. Of those, 23 CR TKAs in 21 patients were available for followup at a minimum of 2 years (mean, 11.2 years; range, 2.3-25.1 years). In this retrospective study, we queried a prospectively maintained database to assess functional outcomes and survivorship. RESULTS: Aseptic loosening-free survival was 100% at 5 and 10 years, and survival with revision for any reason as the outcome was 96% at 5 years (95% confidence interval [CI], 87.7%-100%) and 84% at 10 years (95% CI, 69.5%-100%). One patient was revised for aseptic loosening at 10.2 years postoperatively. Mean Knee Society scores improved from 36±13 preoperatively to 92±9.6 at followup. Extensor lag was present in seven patients preoperatively and only three at followup. Average knee flexion at followup was 112°±12.5°. CONCLUSIONS: In this study we found good long-term survivorship and functional outcomes with a CR implant design in patients following patellectomy. Earlier studies have favored PS over CR implants for patients with patellectomies. We believe this series suggests that CR TKA is indeed an option in patients with patellectomy. LEVEL OF EVIDENCE: Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Spontaneous rupture of the extensor carpi radialis brevis in a 51-year-old man: case report.

Dorsal hand osteophytes are common findings in the general population, frequently presenting with dorsal pain and treated with surgical excision. We report the spontaneous rupture of the extensor carpi radialis brevis in association with a previously asymptomatic dorsal scaphoid spur. Following conservative management, surgical excision of dorsal hand osteophytes should be considered for both resolution of pain and prevention of attritional tendon rupture.

A primate-specific, brain isoform of KCNH2 affects cortical physiology, cognition, neuronal repolarization and risk of schizophrenia.

Organized neuronal firing is crucial for cortical processing and is disrupted in schizophrenia. Using rapid amplification of 5' complementary DNA ends in human brain, we identified a primate-specific isoform (3.1) of the ether-a-go-go-related K(+) channel KCNH2 that modulates neuronal firing. KCNH2-3.1 messenger RNA levels are comparable to full-length KCNH2 (1A) levels in brain but three orders of magnitude lower in heart. In hippocampus from individuals with schizophrenia, KCNH2-3.1 expression is 2.5-fold greater than KCNH2-1A expression. A meta-analysis of five clinical data sets (367 families, 1,158 unrelated cases and 1,704 controls) shows association of single nucleotide polymorphisms in KCNH2 with schizophrenia. Risk-associated alleles predict lower intelligence quotient scores and speed of cognitive processing, altered memory-linked functional magnetic resonance imaging signals and increased KCNH2-3.1 mRNA levels in postmortem hippocampus. KCNH2-3.1 lacks a domain that is crucial for slow channel deactivation. Overexpression of KCNH2-3.1 in primary cortical neurons induces a rapidly deactivating K(+) current and a high-frequency, nonadapting firing pattern. These results identify a previously undescribed KCNH2 channel isoform involved in cortical physiology, cognition and psychosis, providing a potential new therapeutic drug target.

Further evidence for altered myelin biosynthesis and glutamatergic dysfunction in schizophrenia.

Recent studies have provided evidence for neuronal and oligodendrocyte-related abnormalities being associated with schizophrenia. However, the functional interplay and causal relationship between these two abnormalities is poorly understood. In this report, we provide data that identify myelin and fatty-acid biosynthesis dysfunction in schizophrenia based on post-mortem brain studies (prefrontal cortex) utilizing parallel metabolic and transcriptomics investigations. We detected a significant up-regulation of N-acetylaspartate (NAA) by HPLC analysis. Microarray and Q-PCR investigations revealed mRNA abnormalities for several enzymes involved in NAA metabolism. Additionally, glutamatergic neurotransmission components were also found to be affected. Our results suggest that, apart from the previously reported alterations in myelin-related protein synthesis, myelin synthesis itself may be directly affected in schizophrenia as indicated by changes in key enzymes involved in NAA metabolism. A decrease in NAA catabolism in oligodendrocytes would severely reduce acetate levels required to produce myelin lipids and may subsequently affect glutamatergic neurotransmission.

Application and optimization of microarray technologies for human postmortem brain studies.

A number of microarray investigations using human postmortem brain tissue have been published recently, exploring a multitude of human brain disorders with the aim of unraveling the underlying pathologies. Although the technology is still developing and lacks sufficient sensitivity with regard to detecting splice variants and low abundance transcripts, microarrays are becoming the prominent method for candidate gene screening in complex neuropsychiatric disorders. The use of postmortem tissue harbors a variety of potential pitfalls, however, which could result in unreliable or, at worst, meaningless results. During the course of our large-scale gene expression study on 150 human postmortem brain samples, using more than 200 Affymetrix GeneChips, we have identified several aspects within microarray experimental procedure that allows for the early identification of potentially unreliable samples. The general application of the guidelines and technical tips described here increase the efficiency, reliability, and amount of data generated by this powerful screening technology while reducing superfluous consumption of time and resources.