Short-Term Risk Factors for Subtalar Arthrodesis After Primary Tibiotalar Arthrodesis.

While adjacent joint arthritis is a recognized long-term downside of primary tibiotalar arthrodesis (TTA), few studies have identified risk factors for early subtalar arthrodesis (STA) after TTA. This study aims to identify the risk factors for STA within the first few years following TTA. All patients older than 18 years undergoing TTA between 2008 and 2016 were identified retrospectively. Demographic data and comorbidities were collected alongside prior operative procedures, postoperative complications, and subsequent STA. Pre-and postoperative Kellgren-Lawrence osteoarthritis grade of the subtalar joint and postoperative radiographic alignment were obtained. A total of 240 patients who underwent primary TTA were included in this study with median follow up of 13.8 months. Twenty patients (8.3%) underwent STA after TTA due to symptomatic nonunion of TTA in 13 (65%), progression of symptomatic subtalar osteoarthritis (OA) in 4 (20%), and symptomatic nonunion of primary TTA combined progressively symptomatic subtalar OA in 2 (10%). Preoperative radiographic subtalar OA severity and postoperative radiographic alignment were not correlated with subsequent STA. Diabetes mellitus, Charcot arthropathy, neuropathy, alcohol use, substance use disorder, and psychiatric disease were significantly associated with having a subsequent STA. The most common postoperative contributing factor for subsequent STA following primary TTA was the salvage of symptomatic ankle nonunion rather than subtalar joint disease. Patients considering an ankle fusion should be counseled of the risk of subsequent STA, especially if they have risk factors that include diabetes, Charcot arthropathy, neuropathy, alcohol use, substance use disorder, or psychiatric disease.

Epidemiology of Ankle Sprain in the Active-Duty Military Population.

¼: Ankle sprain is one of the most prevalent injuries within the military population, resulting in health-care costs, time away from active duty, and negative impacts on overall readiness. ¼: Female service members appear to be more likely to sustain ankle sprains than male service members. ¼: There is a need for additional research on prevention methods and rehabilitation programs for ankle sprains in the military population because the rate of ankle sprain in this population exceeds that in populations with less physically demanding lifestyles. Consequently, low-cost prevention strategies could yield substantial benefits.

Primary Repair, Reconstruction, and Suture Tape Augmentation All Provide Excellent Outcomes for Lateral Ligament Instability: A Systematic Review.

Purpose: To analyze the literature to compare outcomes and complications following primary lateral ankle ligament repair compared with lateral ankle ligament reconstruction and the suture tape augmentation in patients with lateral ankle instability. Methods: Following the Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) criteria, a systematic literature review using the PubMed/Ovid Medline database was performed (October 11, 1947, to October 1, 2019). Clinical trials that included all the following criteria were considered eligible; published in the English language; patients undergoing primary lateral ankle repair or reconstruction with/without autograft or allograft (anterior talofibular ligament, anterior talofibular ligament + calcaneofibular ligament) or suture tape augmentation; a follow-up at least 1 year; reported least 1 of the measured outcomes (The American Orthopaedic Foot Ankle Score, Karlsson Score, return to sport [RTS], complications, skin wound complications, reoperation). Surgical techniques were evaluated, and studies were subdivided by the following categories: primary repair (PR), reconstruction with graft (GR), and suture tape augmentation (STA). Complications, radiographic outcomes, functional outcome scores, and RTS were analyzed. Results: A total of 41 of 1,991 studies met the criteria for final analysis. This included 1,920 patients who underwent surgical intervention for chronic lateral instability with at least a 1-year follow-up. There were 350 patients who had GR, 1,486 who underwent the PR, and 84 who had STA. GR group appeared to have the lowest rate of complications: GR 3.1% (11 of 350), PR 4.2% (63 of 1486), and STA 10.7% (9 of 84). Postoperative American Orthopaedic Foot Ankle Score ranged from 89.0 to 95.1 for GR and 90.0 to 98.8 for PR. Postoperative Karlsson scores ranged from 80.9 to 94.4 for GR and from 89.2 to 94.1 for PR. Anterior drawer postoperative scores ranged from 1.4 to 30.3 mm for GR, 2.7 to 8.6 mm for PR, and 4.1 to 4.2 mm for STA. Postoperative talar tilt ranged from 2.4 to 7.3° for GR, 1.9 to 6.0° for PR, and 3.6 to 4.5° for STA. RTS ranged from 9.5 to 20.4 weeks for the PR group; one study reported a RTS of 10.6 weeks for STA. Conclusions: Excellent outcomes were noted across all intervention groups. Current literature may suggest there is no difference in functional outcomes between patients treated with PR versus GR. However, there may be a potential improvement in functional outcomes with PR versus STA. Level of Evidence: Level IV, systematic review of Level I to Level IV studies.

Nationwide Analysis of Total Ankle Replacement and Ankle Arthrodesis in Medicare Patients: Trends, Complications, and Cost.

BACKGROUND: Surgical management of end-stage ankle arthritis consists of either ankle arthrodesis (AA) or total ankle replacement (TAR). The purpose of this study was to evaluate utilization trends in TAR and AA and compare cost and complications. METHODS: Medicare patients with the diagnosis of ankle arthritis were reviewed. Patients undergoing surgical intervention were split into AA and TAR groups, which were evaluated for trends as well as postoperative complications, revision rates, and procedure cost. RESULTS: A total of 673 789 patients were identified with ankle arthritis. A total of 19 120 patients underwent AA and 9059 underwent TAR. While rates of AA remained relatively constant, even decreasing, with 2080 performed in 2005 and 1823 performed in 2014, TAR rates nearly quadrupled. Average cost associated with TAR was $12559.12 compared with $6962.99 for AA (P < .001). Overall complication rates were 24.9% in the AA group with a 16.5% revision rate compared with 15.1% and 11.0%, respectively, in the TAR group (P < .001). Patients younger than 65 years had both higher complication and revision rates. DISCUSSION: TAR has become an increasingly popular option for the management of end-stage ankle arthritis. In our study, TAR demonstrated both lower revision and complication rates than AA. However, TAR represents a more expensive treatment option. LEVELS OF EVIDENCE: Level III: Retrospective comparative study.

Bröstrom Repair Review.

Since its introduction in 1966, the Bröstrom repair has been the workhorse for the treatment of chronic ankle instability. The procedure has expanded with the advent of arthroscopy, ultrasound, and other techniques. Because chronic ankle sprains/instability pose a barrier to athletes who perform high-level activities for a living, discussions concerning postoperative recovery and return to play criteria are important. Here we present an update on the Bröstrom-Gould procedure from preoperative management to return to play.Level of Evidence: Level V.

Unicompartmental knee arthroplasty: A PearlDiver study evaluating complications rates, opioid use and utilization in the Medicare population.

PURPOSE: Despite increased utilization of unicompartmental knee arthroplasty (UKA) for unicompartmental knee osteoarthritis, outcomes in Medicare patients are not well-reported. The purpose of this study is to analyze practice patterns and outcome differences between UKA and TKA in the Medicare population. It is hypothesized that UKA utilization will have increased over the course of the study period and that UKA will be associated with reduced opioid use and lower complication rates compared to TKA. METHODS: Using PearlDiver, the Humana Claims dataset and the Medicare Standard Analytic File (SAF) were analyzed. Patients who underwent UKA and TKA were identified by CPT codes. Postoperative complications were identified by ICD-9/ICD-10 codes. Opioid use was analyzed by the number of days patients were prescribed opioids postoperatively. Survivorship was defined as conversion to TKA. RESULTS: In the Humana dataset, 7,808 UKA and 150,680 TKA patients were identified. 8-year survivorship was 87.7% (95% CI [0.861,0.894]). Postoperative opioid use was significantly higher after TKA (186.1 days) compared to UKA (144.7 days) (p < 0.01, Δ = 41.1, 95% CI = [30.41, 52.39]). In the SAF dataset, 20,592 UKA patients and 110,562 TKA patients were identified. Survivorship was highest in patients > 80 years old and lowest in patients < 70 years old. In both datasets, postoperative complication rates were higher in TKA patients compared to UKA patients in nearly all categories. CONCLUSIONS: UKA represents an increasingly utilized treatment for osteoarthritis in the Medicare population and may be comparatively advantageous to TKA due to reduced opioid use and complication rates after surgery. LEVEL OF EVIDENCE: Level III.

Early Versus Delayed Mobilization Post-Operative Protocols for Primary Lateral Ankle Ligament Reconstruction: A Systematic Review and Meta-Analysis.

INTRODUCTION: Lateral ankle instability represents a common orthopaedic diagnosis. Nonoperative treatment through focused physical therapy provides satisfactory results in most patients. However, some patients experience persistent chronic lateral ankle instability despite appropriate nonoperative treatment. These patients may require stabilization, which can include primary lateral ligament reconstruction with a graft to restore ankle stability. Optimal post-operative rehabilitation of lateral ankle ligament reconstruction remains unknown, as surgeons vary in how long they immobilize their patients post-operatively. The aim of this review was to provide insight into early mobilization (EM) versus delayed mobilization (DM) post-operative protocols in patients undergoing primary lateral ankle ligament reconstructions to determine if an optimal evidence-based post-operative rehabilitation protocol exists in the literature. METHODS: Following PRIMSA criteria, a systematic review/meta-analysis using the PubMed/Ovid Medline database was performed (10/11/1947 - 1/28/2020). Manuscripts that were duplicates, non-lateral ligament repair, biomechanical, and non-English language were excluded. Protocols were reviewed and divided into two categories: early mobilization (within three weeks of surgery) and delayed mobilization (after three weeks of surgery). Functional outcome scores (American Orthopedic Foot and Ankle Society Score (AOFAS), Karlsson scores), radiographic measurements (anterior drawer, talar tilt), and complications were evaluated using weighted mean differences (pre- and post-operative scores) and mixed-effect models. RESULTS: After our search, twelve out of 1,574 studies met the criteria for the final analysis, representing 399 patients undergoing lateral ankle reconstruction. Using weighted mean differences the DM group showed superior AOFAS functional scores compared to the EM group (28.0 (5.5) vs. 26.3 (0.0), respectively; p < 0.001), although sample size was small. Conversely, no significant differences were found for Karlsson functional score (p = 0.246). With regards to radiographic outcome, no significant differences were observed; anterior drawer was p = 0.244 and talar tilt was p = 0.937. A meta-analysis using mixed-effects models confirmed these results, although heterogeneity was high. CONCLUSIONS: While there are some conflicting results, the findings indicated the timing of post-operative mobilization made no difference in functional outcomes or post-operative stability for patients undergoing lateral ankle ligament reconstruction. Because heterogeneity was high, future studies are needed to evaluate these protocols in less diverse patient groups and/or more consistent techniques for lateral ankle ligament reconstruction.

Weightbearing Protocols After Posterolateral Corner Reconstruction: A Systematic Review.

BACKGROUND: Multiligamentous knee injuries with a posterolateral corner injury represent a devastating insult to the knee. PURPOSE: To evaluate multiligamentous knee reconstruction rehabilitation programs and recommend a rehabilitation program based on a review of published outcomes studies. STUDY DESIGN: Systematic review; Level of evidence, 4. METHODS: A MEDLINE (PubMed), OVID, and Embase database search was conducted using the terms "posterolateral corner" and "rehabilitation." All articles obtained were examined to confirm their rehabilitation programs for multiligamentous knee injuries. These injuries included a posterolateral corner injury plus an isolated anterior or posterior cruciate ligament injury or a combined cruciate injury. RESULTS: Ten publications representing 245 patients with multiligamentous knee reconstruction were analyzed. Rehabilitation protocols were divided by weightbearing (WB) status: in 2 studies, patients were non-WB until postoperative 4 weeks (delayed WB; n = 61); 5 studies permitted progressive WB until postoperative 6 weeks (progressive WB; n = 123); and 3 studies allowed WB immediately after surgery (immediate WB; n = 61). No significant difference in outcome scores among the 3 WB groups was found. Arthrofibrosis requiring manipulation under anesthesia was the most common complication (11%) in the delayed WB group, followed by the immediate WB group (3%) and the progressive WB group (0%; P < .01). Overall complication rates were highest in the delayed WB group (44%), followed by the immediate and progressive WB groups (25% and 3%, respectively; P < .00001). The delayed WB group was permitted to return to sport at a mean of 10.5 months from the index procedure; the progressive WB group, at 6.0 months; and the immediate WB group, at 9.0 months (P < .05). CONCLUSION: This review revealed no significant difference in outcome scores when comparing immediate, progressive, and delayed WB protocols. Time to permitted return to sport was not significantly different among the groups, but there existed a trend toward earlier return in the progressive WB group. Patients in the delayed and immediate WB groups experienced a higher overall complication rate. Progressive WB postoperative protocols may decrease the risk of complications without compromising outcomes; however, more research is needed to identify the optimal postoperative rehabilitation protocol, given the significant data heterogeneity currently available in the literature.

Diagnosis and Treatment of Chronic Lateral Ankle Instability: Review of Our Biomechanical Evidence.

Definitive diagnosis and optimal surgical treatment of chronic lateral ankle instability remains controversial. This review distills available biomechanical evidence as it pertains to the clinical assessment, imaging work up, and surgical treatment of lateral ankle instability. Current data suggest that accurate assessment of ligament integrity during physical examination requires the ankle to ideally be held in 16° of plantar flexion when performing the anterior drawer test and 18° of dorsiflexion when performing the talar tilt test, respectively. Stress radiographs are limited by their low sensitivity, and MRI is limited by its static nature. Surgically, both arthroscopic and open repair techniques appear biomechanically equivalent in their ability to restore ankle stability, although sufficient evidence is still lacking for any particular procedure to be considered a superior construct. When performing reconstruction, grafts should be tensioned at 10 N and use of nonabsorbable augmentations lacking viscoelastic creep must factor in the potential for overtensioning. Anatomic lateral ligament surgery provides sufficient biomechanical strength to safely enable immediate postoperative weight bearing if lateral ankle stress is neutralized with a boot. Further research and comparative clinical trials will be necessary to define which of these ever-increasing procedural options actually optimizes patient outcome for chronic lateral ankle instability.

Early Versus Delayed Mobilization Postoperative Protocols for Lateral Ankle Ligament Repair: A Systematic Review and Meta-analysis.

BACKGROUND: The majority of patients with an acute lateral ankle ligamentous injury are successfully treated nonoperatively with functional rehabilitation; however, a small proportion of these patients experience persistent chronic instability and may require surgical intervention. Delayed primary repair of the ruptured ligaments is most commonly indicated for these patients. Optimal rehabilitation after lateral ankle ligament repair remains unknown, as surgeons vary in how they balance protection of the surgical repair site with immobilization against the need for ankle joint mobilization to restore optimal postoperative ankle range of motion. PURPOSE: To compare early and delayed mobilization (EM and DM, respectively) postoperative protocols in patients undergoing primary lateral ankle ligament repair to determine optimal evidence-based rehabilitation recommendations. STUDY DESIGN: Systematic review; Level of evidence, 4. METHODS: Following the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines, a meta-analysis using the PubMed/Ovid MEDLINE database was performed (October 11, 1947 to October 16, 2017), searching for articles involving lateral ankle ligament repair. Postoperative protocols were reviewed and divided into 2 categories: EM (within 3 weeks of surgery) and DM (more than 3 weeks post surgery). Return to sport (RTS), outcome scores (American Orthopaedic Foot and Ankle Society [AOFAS] ankle-hindfoot scale and Karlsson score), radiographic outcomes (talar tilt and anterior drawer), and complications of both populations were recorded and statistically analyzed. RESULTS: A total of 28 of 1574 studies met the criteria for the final analysis, comprising 1457 patients undergoing primary lateral ankle ligament repair. The postoperative AOFAS score was significantly greater in the EM versus DM group (98.8 vs 91.9, respectively; P < .001), as was the postoperative Karlsson score (92.2 vs 90.0, respectively; P < .001). However, the EM group had significantly greater postoperative laxity on both the anterior drawer test (6.3 vs 3.9 mm, respectively; P < .001) and talar tilt test (5.1° vs 4.5°, respectively; P < .001). Also, the DM group had significantly lower rates of overall complications (3.1% vs 11.4%, respectively; P < .001) and skin wound complications (1.3% vs 3.8%, respectively; P = .005). RTS was not significantly different between groups (P = .100). CONCLUSION: Patients with EM postoperative protocols demonstrated improved functional outcomes; however, the EM group had increased objective laxity and a higher complication rate. Additional randomized studies are needed to definitively evaluate early versus delayed rehabilitation protocol timetables to optimize functional outcomes without compromising long-term stability.

The Complete Genome Sequence of n-Alkane-Degrading Desulfoglaeba alkanexedens ALDC Reveals Multiple Alkylsuccinate Synthase Gene Clusters.

Anaerobic alkane metabolism is critical in multiple environmental and industrial sectors, including environmental remediation, energy production, refined fuel stability, and biocorrosion. Here, we report the complete gap-closed genome sequence for a model n-alkane-degrading anaerobe, Desulfoglaeba alkanexedens ALDC.

Increased rates of knee arthroplasty and cost of patients with meniscal tears treated with arthroscopic partial meniscectomy versus non-operative management.

PURPOSE: The purpose of this study was to determine the cost of arthroscopic partial meniscectomy (APM), one of the most common surgeries performed by orthopaedic surgeons, and the associated rate of progression to knee arthroplasty (KA) compared to patients treated non-operatively after diagnosis of meniscal tear. METHODS: Utilizing data mining software (PearlDiver, Colorado Springs, CO), a national insurance database of approximately 23.5 million orthopaedic patients was queried for patients diagnosed with a meniscal tear. Patients were classified by treatment: non-operative and arthroscopic partial meniscectomy and were followed after initial diagnosis for cost and progression to knee arthroplasty. RESULTS: There were 176,407 subjects in the non-op group and 114,194 subjects in the arthroscopic partial meniscectomy group. Arthroscopic partial meniscectomy generated more cost than non-operative ($3842.57 versus $411.05, P < 0.001). Arthroscopic partial meniscectomy demonstrated greater propensity to need future knee arthroplasty (11.4% at 676 days) than those treated non-operatively (9.5% at 402 days) (P < 0.001). Female patients demonstrated a higher rate of progression to knee arthroplasty in the arthroscopic partial meniscectomy and non-operative groups (P < 0.001). CONCLUSION: Compared to non-operative treatment for meniscal tears, arthroscopic partial meniscectomy is more expensive and does not appear to decrease the rate of progression to knee arthroplasty. Patients undergoing arthroscopic partial meniscectomy yielded on average a delay of only 9 months (274 days) before undergoing knee arthroplasty. Female patients experienced a significantly higher rate of progression to knee arthroplasty. The authors recognize the limitations of this type of study including its retrospective nature, reliance upon accurate coding and billing information, and the inability to determine whether symptoms including mechanical locking played a role in the decision to perform an APM. LEVEL OF EVIDENCE: IV.

Cost comparison and complication rate of Lisfranc injuries treated with open reduction internal fixation versus primary arthrodesis.

BACKGROUND: Controversy exists regarding optimal primary management of Lisfranc injuries. Whether open reduction internal fixation (ORIF) or primary arthrodesis is superior remains unknown. METHODS: A national insurance database of approximately 23.5 million orthopedic patients was retrospectively queried for subjects who were diagnosed with a Lisfranc injury from 2007 to 2016 based on international classification of diseases (ICD) codes (PearlDiver, Colorado Springs, CO). Patients with lisfranc injuries then progressed to either nonoperative treatment, ORIF, or primary arthrodesis. Associated treatment costs were determined along with complication rate and hardware removal rate. RESULTS: 2205 subjects with a diagnosis of Lisfranc injury were identified in the database. 1248 patients underwent nonoperative management, 670 underwent ORIF, and 212 underwent primary arthrodesis. The average cost of care associated with primary arthrodesis was greater ($5005.82) than for ORIF ($3961.97,P = 0.045). The overall complication rate was 23.1% (155/670) for ORIF and 30.2% (64/212) for primary arthrodesis (P = 0.04). Rates of hardware removal were 43.6% (292/670) for ORIF and 18.4% (39/212) for arthrodesis (P < 0.001). Furthermore, 2.5% (17/670) patients in the ORIF group progressed to arthrodesis at a mean of 308 days, average cost of care associated with this group of patients was $9505.12. DISCUSSION: Primary arthrodesis is both significantly more expensive and has a higher complication rate than ORIF. Open reduction and internal fixation demonstrated a low rate of progression to arthrodesis, although there was a high rate of hardware removal, which may represent a planned second procedure in the management of a substantial number of patients treated with ORIF. LEVEL OF EVIDENCE: Level III Retrospective Cohort Study.

Lariat sign: An MRI finding associated with common peroneal nerve rupture.

Traumatic knee dislocation represents a catastrophic orthopedic injury with potentially devastating vascular and neurologic injuries. We report a case of common peroneal nerve rupture sustained during a knee dislocation with novel radiographic findings that we describe as a lariat sign. At the site of rupture, the distal nerve loops back on itself forming a lasso shape or lariat. This thickened nerve's abnormal course should not be misinterpreted as a vessel.

Gastrocnemius Recession for Metatarsalgia.

Metatarsalgia is a common cause of plantar forefoot pain. Causes of metatarsalgia include foot anatomy, gait mechanics, and foot and ankle deformity. One specific cause, mechanical metatarsalgia, occurs because of gastrocnemius muscle contracture, which overloads the forefoot. Muscular imbalance of the gastrocnemius complex alters gait mechanics, which increases recruitment of the toe extensor musculature, thereby altering forefoot pressure. Patients with concomitant metatarsalgia and gastrocnemius contracture demonstrate ankle equinus and a positive Silfverskiold test. Nonoperative therapeutic modalities are mainstays of treatment. In patients in whom these treatments fail to provide metatarsalgia symptomatic relief, gastrocnemius muscle lengthening is a therapeutic option.

Membrane Lipids as Indicators for Viable Bacterial Communities Inhabiting Petroleum Systems.

Microbial activity in petroleum reservoirs has been implicated in a suite of detrimental effects including deterioration of petroleum quality, increases in oil sulfur content, biofouling of steel pipelines and other infrastructures, and well plugging. Here, we present a biogeochemical approach, using phospholipid fatty acids (PLFAs), for detecting viable bacteria in petroleum systems. Variations within the bacterial community along water flow paths (producing well, topside facilities, and injection well) can be elucidated in the field using the same technique, as shown here within oil production plants in the Molasse Basin of Upper Austria. The abundance of PLFAs is compared to total cellular numbers, as detected by qPCR of the 16S rDNA gene, to give an overall comparison between the resolutions of both methods in a true field setting. Additionally, the influence of biocide applications on lipid- and DNA-based quantification was investigated. The first oil field, Trattnach, showed significant PLFA abundances and cell numbers within the reservoir and topside facilities. In contrast, the second field (Engenfeld) showed very low PLFA levels overall, likely due to continuous treatment of the topside facilities with a glutaraldehyde-based antimicrobial. In comparison, Trattnach is dosed once per week in a batch fashion. Changes within PLFA compositions across the flow path, throughout the petroleum production plants, point to cellular adaptation within the system and may be linked to shifts in the dominance of certain bacterial types in oil reservoirs versus topside facilities. Overall, PLFA-based monitoring provides a useful tool to assess the abundance and high-level taxonomic diversity of viable microbial populations in oil production wells, topside infrastructure, pipelines, and other related facilities.

Open physeal fracture of the distal phalanx of the hallux.

Open physeal fractures of the distal phalanx of the hallux are the lesser described counterpart to the same fracture of the finger, known by its eponym as a "Seymour fracture". Displaced Salter-Harris phalangeal fractures present with a concomitant nailbed or soft tissue injury. Often these fractures occur in the summer months when open-toe footwear can be worn, however, they may occur indoors as well. Frequently, the injury results from direct axial load of the toe, or "stubbing", which causes the fracture and associated soft tissue injury. Prompt diagnosis and appropriate treatment is necessary to prevent negative sequelae such as osteomyelitis, malunion, nonunion, or premature growth arrest. In this article, we present a 12year-old male who sustained an open physeal fracture of the distal phalanx when he "stubbed" his great toe on a bed post. His injury was initially misdiagnosed at an urgent care facility, thereby delaying appropriate intervention and necessitating an operative surgical procedure. Additionally, we review the existing literature discussing these infrequently reported injuries, as well as present key points as they pertain to the diagnosis and management of this injury in the emergency department.

Clinical and Functional Outcomes of the Birmingham Hip Resurfacing System.

This study reported the outcomes of patients treated with the Birmingham Hip Resurfacing System (Smith & Nephew, Memphis, Tennessee) to identify the prevalence of complications and failures. A retrospective review of 202 patients (206 hips) was performed. Outcomes were assessed clinically with Harris Hip Score at 6 and 12 months and then yearly. Subanalysis was performed, with the hips divided according to patient sex and size of the femoral component. Mean patient age was 51±8 years, and mean follow-up was 4±1.6 years. Of the patients, 163 were men (83%) and 35 were women (17%). Postoperative improvement was significant, with preoperative Harris Hip Score of 62.9±10.6 and postoperative Harris Hip Score of 98.6±6.7 (P<.001). There were 9 patients (4%) who had complications. A total of 5 hips (2.4%) underwent revision. At 3 years, mean survival was better for men than for women (99% vs 92%, respectively). Survival was lowest in patients with femoral component diameter of less than 46 mm. According to the authors' results, the Birmingham Hip Resurfacing System resulted in good clinical outcomes at 4 years. Survival and outcomes in women, particularly those with modest bone size, are inferior.

A PCR-based assay for the detection of anaerobic naphthalene degradation.

Polycyclic aromatic hydrocarbons (PAH) are widespread environmental pollutants of considerable risk to human health. The aerobic degradation of PAH via oxygenase reactions has been studied for several decades. In contrast, it was not until very recent that the first key enzyme involved in anaerobic PAH degradation, the dearomatizing 2-naphthoyl-CoA reductase, was isolated and characterized. In this work, a PCR-based functional assay was developed to detect microorganisms that have the ability to anaerobically degrade naphthalene, as a model for larger PAH. The degenerative oligonucleotide probes introduced here amplified a highly conserved region of the gene encoding 2-naphthoyl-CoA reductase (Ncr) in numerous sulfate-reducing pure cultures and environmental enrichments. The assay provides the first molecular tool for monitoring the anaerobic degradation of a model PAH.

Anaerobic degradation of homocyclic aromatic compounds via arylcarboxyl-coenzyme A esters: organisms, strategies and key enzymes.

Next to carbohydrates, aromatic compounds are the second most abundant class of natural organic molecules in living organic matter but also make up a significant proportion of fossil carbon sources. Only microorganisms are capable of fully mineralizing aromatic compounds. While aerobic microbes use well-studied oxygenases for the activation and cleavage of aromatic rings, anaerobic bacteria follow completely different strategies to initiate catabolism. The key enzymes related to aromatic compound degradation in anaerobic bacteria are comprised of metal- and/or flavin-containing cofactors, of which many use unprecedented radical mechanisms for C-H bond cleavage or dearomatization. Over the past decade, the increasing number of completed genomes has helped to reveal a large variety of anaerobic degradation pathways in Proteobacteria, Gram-positive microbes and in one archaeon. This review aims to update our understanding of the occurrence of aromatic degradation capabilities in anaerobic microorganisms and serves to highlight characteristic enzymatic reactions involved in (i) the anoxic oxidation of alkyl side chains attached to aromatic rings, (ii) the carboxylation of aromatic rings and (iii) the reductive dearomatization of central arylcarboxyl-coenzyme A intermediates. Depending on the redox potential of the electron acceptors used and the metabolic efficiency of the cell, different strategies may be employed for identical overall reactions.