Retrospective Analysis of the Akin Osteotomy

Hallux abductovalgus is one of the most common deformities addressed by foot and ankle surgeons. Surgically, it can be approached using a wide variety of procedures. After performing the first metatarsal osteotomy, the final step is often to realign the great toe in a rectus position. This is performed with an osteotomy of the proximal phalanx. The Akin osteotomy is a medially based closing wedge osteotomy of the proximal phalanx. When executing the osteotomy, the goal is not only to correct abduction, but also to keep the lateral cortex intact, which allows it to act as an additional point of fixation. However, the lateral cortex can be iatrogenically compromised during surgery or in the postoperative period. We investigated the frequency of disruption of the lateral cortex, osteotomy displacement, healing time, and the need for surgical revision associated with the Akin procedure. A total of 132 patients who had undergone Akin osteotomy were included in the present retrospective study. Intraoperative fluoroscopy showed the lateral cortex was compromised in 47 (35.6%) patients and remained intact for 85 (64.4%) patients. Of the 47 (35.6%) patients with lateral cortex disruption intraoperatively, 9 (19.1%) experienced displacement during the postoperative period, of whom, 3 (6.38%) required surgical revision. Although intact during surgery, the other 6 (4.55%) patients sustained lateral cortex fractures postoperatively, 2 (33.3%) of whom required surgical revision. A statistically significant difference was found between the integrity of the lateral cortical hinge and the healing time of the osteotomy. All the osteotomies with displacement postoperatively were noted to have lateral cortex failure, either during surgery or during the follow-up period.     

Magnetic resonance imaging of the lumbar spine: determining clinical impact and potential harm from overuse

Background

Lumbar spine magnetic resonance imaging is frequently said to be “overused” in the evaluation of low back pain, yet data concerning the extent of overuse and the potential harmful effects are lacking.

Fourteen Year Follow-Up of Randomized Clinical Trials of Active Robotic-Assisted Total Hip Arthroplasty

Background

Active robotic total hip arthroplasty (THA) has been used clinically for over 20 years, but long-term results have never been studied. The aims of this study are to determine whether active robotic THA improves clinical outcomes and results in fewer revisions over a long-term follow-up.

Comparative effectiveness of a bioengineered living cellular construct vs. a dehydrated human amniotic membrane allograft for the treatment of diabetic foot ulcers in a real world setting

We evaluated the comparative effectiveness of a bioengineered living cellular construct (BLCC) and a dehydrated human amnion/chorion membrane allograft (dHACM) for the treatment of diabetic foot ulcers (DFUs). Using a wound care–specific electronic medical record database, we assessed real‐world outcomes in 218 patients with 226 DFUs receiving treatment in 2014 at 99 wound care centers. The analysis included DFUs ≥1 and <25 cm² with duration <=1 year and area reduction ≤20% in 14 days prior to treatment (N=163, BLCC; N=63, dHACM). The average baseline areas and durations were 6.0 cm² and 4.4 months for BLCC and 5.2 cm² and 4.6 months for dHACM, respectively. Patients treated with dHACM had more applications compared to those treated with BLCC (median 3.0 vs. 2.0) (p=0.003). A Cox model adjusted for key covariates including area and duration found the median time to closure for BLCC was 13.3 weeks compared to 26 weeks for dHACM, and the proportion of wounds healed were significantly higher for BLCC by 12 weeks (48% vs. 28%) and 24 weeks (72% vs. 47%) (p=0.01). Treatment with a bioengineered living cellular technology increased the probability of healing by 97% compared with a dehydrated amniotic membrane (hazard ratio = 1.97 [95% confidence interval 1.17, 3.33], p=0.01).     

E1 of α-ketoglutarate dehydrogenase defends Mycobacterium tuberculosis against glutamate anaplerosis and nitroxidative stress

Enzymes of central carbon metabolism (CCM) in Mycobacterium tuberculosis (Mtb) make an important contribution to the pathogen’s virulence. Evidence is emerging that some of these enzymes are not simply playing the metabolic roles for which they are annotated, but can protect the pathogen via additional functions. Here, we found that deficiency of 2-hydroxy-3-oxoadipate synthase (HOAS), the E1 component of the α-ketoglutarate (α-KG) dehydrogenase complex (KDHC), did not lead to general metabolic perturbation or growth impairment of Mtb, but only to the specific inability to cope with glutamate anaplerosis and nitroxidative stress. In the former role, HOAS acts to prevent accumulation of aldehydes, including growth-inhibitory succinate semialdehyde (SSA). In the latter role, HOAS can participate in an alternative four-component peroxidase system, HOAS/dihydrolipoyl acetyl transferase (DlaT)/alkylhydroperoxide reductase colorless subunit gene (ahpC)-neighboring subunit (AhpD)/AhpC, using α-KG as a previously undescribed source of electrons for reductase action. Thus, instead of a canonical role in CCM, the E1 component of Mtb’s KDHC serves key roles in situational defense that contribute to its requirement for virulence in the host. We also show that pyruvate decarboxylase (AceE), the E1 component of pyruvate dehydrogenase (PDHC), can participate in AceE/DlaT/AhpD/AhpC, using pyruvate as a source of electrons for reductase action. Identification of these systems leads us to suggest that Mtb can recruit components of its CCM for reactive nitrogen defense using central carbon metabolites.The bacterium Mycobacterium tuberculosis (Mtb), which causes tuberculosis, has plagued humanity since antiquity (1), is estimated to infect one-third of the population today, and is the leading cause of death by a bacterium. This success as a pathogen reflects Mtb’s metabolic plasticity and resistance to host immunity (2, 3). Recent evidence suggests that certain enzymes of central carbon metabolism (CCM) can mediate both of these facets of Mtb’s adaptation to the host (4–8). Here, we demonstrate that Rv1248c, recently named 2-hydroxy-3-oxoadipate synthase (HOAS) (9), is one such enzyme.Rv1248c was first annotated as the thiamin diphosphate (ThDP)-dependent E1 component (SucA) of a canonical α-ketoglutarate (α-KG) dehydrogenase complex (KDHC) that produces succinyl CoA (SucCoA) via oxidative decarboxylation of α-KG with concomitant transfer of the resulting succinyl group to CoA (10). Classically, KDHC, composed of three enzymes, joins the oxidative and reductive half-cycles of the TCA cycle (SI Appendix, Fig. S1). The TCA cycle generates high-energy phosphate bonds and biosynthetic precursors of amino acids, nucleotides, and fatty acids (11). However, KDHC activity was not detected in Mtb lysates, and the gene product annotated as the lipoamide-bearing E2 component [Rv2215, dihydrolipoyl succinyl transferase (SucB)] functions as the E2 component dihydrolipoyl acetyl transferase (DlaT) of the pyruvate dehydrogenase complex (PDHC) (5, 12, 13). The Mtb genome does not encode another SucB (12), and KDHC activity could not be demonstrated with purified recombinant Rv1248c plus DlaT and E3 [lipoamide dehydrogenase (Lpd)] in a manner similar to cognate proteins from other actinomycetes (14). Rv1248c by itself produces succinate semialdehyde (SSA) from nonoxidative decarboxylation of α-KG in vitro, and Mtb’s succinate semialdehyde dehydrogenases (SSADHs) can generate succinate from SSA, completing a modified TCA cycle (13). Subsequently, activity-based metabolomic profiling revealed yet another function of Rv1248c that predominated over SSA production: decarboxylation of α-KG, followed by carboligation with glyoxylate to form 2-hydroxy-3-oxoadipate (HOA). Thus, Rv1248c was renamed HOAS (9). Decarboxylation of α-KG is the first step in all three reactions. The Mycobacterium smegmatis α-ketoglutarate decarboxylase (MsKGD) homolog was found to catalyze all three reactions in vitro, with augmentation of catalysis by acetyl CoA (AcCoA)-mediated allosteric modulation (15), whereas Mtb HOAS showed a kinetic preference for the HOAS pathway in vitro (16).HOAS activity is regulated in Mtb by glycogen accumulation regulator A (GarA), whose activity is controlled, in turn, by Ser/Thr kinases PknG and PknB (SI Appendix, Fig. S1B). GarA also regulates glutamate dehydrogenase (GDH) and glutamate synthase/glutamine oxoglutarate aminotransferase (17). Coregulation of these three enzymes by GarA calls attention to the contribution of HOAS to Mtb’s metabolism of glutamate. Glutamate serves as an anaplerotic substrate entering the TCA cycle as α-KG and is also a key intermediate in nitrogen assimilation and metabolism (18, 19).Despite extensive studies, the physiological function of HOAS in Mtb and its contribution to virulence remain unknown. Here, we brought genetics, metabolomics, enzymology, and mouse models of infection to bear on that question, using the hoas deletion mutant in Mtb and the deletion mutant complemented in three ways: with the WT allele, with an allele with a point mutation that abrogates catalysis, or with an allele with a point mutation that is insensitive to allosteric regulation by AcCoA. In standard culture conditions, Δhoas showed no defect in growth or changes in levels of CCM metabolites, arguing against Mtb’s reliance on the conventional function of KDHC. However, situational stresses revealed striking phenotypes in Δhoas, indicative of a defensive role of HOAS against products arising from metabolism of glutamate and against reactive nitrogen intermediates (RNIs). Mechanistic analysis of the latter phenotype revealed a previously undescribed route to antioxidant defense mediated by substrates and enzymes of CCM.