Electrochemical checking of aerobic isolates from electrochemically active biofilms formed in compost.

AIMS: To design a cyclic voltammetry (CV) procedure to check the electrochemical activity of bacterial isolates that may explain the electrochemical properties of biofilms formed in compost. METHODS AND RESULTS: Bacteria catalysing acetate oxidation in garden compost were able to form electrochemically active biofilms by transferring electrons to an electrode under chronoamperometry. They were recovered from the electrode surface and identification of the isolates using 16S rRNA sequencing showed that most of them were Gammaproteobacteria, mainly related to Enterobacter and Pseudomonas spp. A CV procedure was designed to check the electrochemical activity of both groups of isolates. Preliminary CVs suggested that the bacteria were not responsible for the catalysis of acetate oxidation. In contrast, both groups of isolates were found to catalyse the electrochemical reduction of oxygen under experimental conditions that favoured adsorption of the microbial cells on the electrode surface. CONCLUSIONS: Members of the genera Enterobacter and Pseudomonas were found to be able to catalyse the electrochemical reduction of oxygen. SIGNIFICANCE AND IMPACT OF THE STUDY: This study has shown the unexpected efficiency of Enterobacter and Pseudomonas spp. in catalysing the reduction of oxygen, suggesting a possible involvement of these species in biocorrosion, or possible application of these strains in designing bio-cathode for microbial fuel cells.

Deferribacter abyssi sp. nov., an anaerobic thermophile from deep-sea hydrothermal vents of the Mid-Atlantic Ridge.

Two strains of thermophilic, anaerobic, chemolithoautotrophic bacteria, designated JR(T) and DR, were isolated from hydrothermal samples collected on the Mid-Atlantic Ridge from the Rainbow (36 degrees 16' N, 33 degrees 54' W) and Menez Gwen (37 degrees 50' N, 31 degrees 50' W) vent fields, respectively. Cells of both isolates were short, straight- to vibrio-shaped, motile rods with one polar flagellum, and were Gram-negative and non-sporulating. Strain JR(T) was characterized in detail. It was found to grow optimally at pH 6.5-6.7, at 60 degrees C and in the presence of 30 g NaCl l(-1). Strain JR(T) could use molecular hydrogen, acetate, succinate, pyruvate and proteinaceous compounds as electron donors, and elemental sulfur, nitrate or Fe(III) as electron acceptors. No fermentation of organic substrates occurred. The G+C content of the DNA of strain JR(T) was 30.8 mol%. Strain DR (=DSM 14927) possessed the same morphology and pH, temperature and salinity optima and ranges, and used the same electron acceptors as strain JR(T). On the basis of their 16S rDNA sequences (1517 nucleotides), strains JR(T) and DR were identical and distantly related to Deferribacter thermophilus and Deferribacter desulfuricans (95.3 and 95.2 % sequence similarity, respectively). Based on their phenotypic and phylogenetic characteristics, it is proposed that both strains are members of a new species of the genus Deferribacter, for which the name Deferribacter abyssi (type strain JR(T)=DSM 14873(T)=JCM 11955(T)) is proposed.

Vulcanithermus mediatlanticus gen. nov., sp. nov., a novel member of the family Thermaceae from a deep-sea hot vent.

A novel thermophilic, microaerophilic, facultatively chemolithoheterotrophic bacterium designated strain TR(T) was isolated from a sample of a deep-sea hydrothermal chimney collected at the Rainbow vent field on the Mid-Atlantic Ridge (36 degrees 14'N). Gram-negative, non-spore-forming, non-motile rods occurred singly or in pairs. The organism grew in the temperature range 37-80 degrees C with an optimum at 70 degrees C and at pH 5.5-8.4 with an optimum around 6.7. The NaCl range for growth was 10-50 g l(-1) with an optimum of 30 g l(-1). Strain TR(T) grew chemoorganoheterotrophically with carbohydrates, proteinaceous substrates, organic acids and alcohols using oxygen or nitrate as electron acceptors. The isolate was able to grow at oxygen concentrations from 0.5 to 21%. Oxygen concentrations that promoted fastest growth ranged from 4 to 8% under agitation. The novel isolate was able to grow lithoheterotrophically with molecular hydrogen as the energy source. The G + C content of the genomic DNA was 68.4 mol%. Phylogenetic analysis of the 16S rDNA sequence placed strain TR(T) within the phylum Deinococcus-Thermus of the Bacteria. On the basis of phenotypic and phylogenetic data, it is proposed that this isolate should be described as a member of a novel species of a new genus as Vulcanithermus mediatlanticus gen. nov., sp. nov. The type strain is TR(T) (= DSM 14978T = VKM B-2292T = JCM 11956T).

Nerve injury after primary total knee arthroplasty.

There is controversy about the incidence of and predisposing factors to the development of peripheral nerve palsy after total knee arthroplasty (TKA). In this study, 19 patients with a documented neurologic complication were identified after a retrospective review of 1,476 primary TKAs performed between January 1970 and December 1998 at the New York Presbyterian Hospital at Columbia University, for an overall incidence of 1.3%. Contrary to previously published data, valgus deformity, flexion contracture, the use of postoperative epidural anesthesia, the prolonged use of pneumatic tourniquets, and preexisting neuropathy were not associated with the development of peripheral neuropathy after TKA based on our data. A larger percentage of rheumatoid knees experienced a neurologic injury than was expected, however. No other significant risk factors for peripheral neuropathy after TKA were identified based on data from our patients. Immediately after discovery of the nerve palsy, conservative treatment was employed for each of our patients. All patients showed at least a partial recovery at the end of follow-up, with most experiencing a complete recovery from symptoms.

Anterior cruciate ligament function after tibial eminence fracture in skeletally mature patients.

We compared anterior cruciate ligament function in skeletally mature patients after treatment of tibial eminence fractures with that of patients in two other groups: patients who had anterior cruciate ligament deficiency and patients who had undergone anterior cruciate ligament reconstruction using bone-patellar tendon-bone autografts. The Lysholm questionnaire was used to evaluate symptoms and KT-1000 arthrometry was used to determine objective knee laxity at an average follow-up of 5.2 years. Knee joint proprioception was assessed with a new method designed to test joint position sense. The Lysholm score for the tibial eminence group was 94 +/- 7. Only the patients in the anterior cruciate ligament-deficient group demonstrated statistically significantly increased laxity and inferior proprioception when the injured leg was compared with the uninjured leg. Both laxity and proprioception were statistically inferior for the anterior cruciate ligament-deficient group when compared with both the treated tibial eminence fracture group and the anterior cruciate ligament-reconstructed group. No statistically significant difference was observed between the anterior cruciate ligament-reconstructed and treated tibial eminence fracture groups. Correlation was observed between laxity and proprioception when all patients were analyzed. The results demonstrate that appropriate treatment of tibial eminence fractures restores stability and proprioception to the knee.

Clinical and radiographic results of cementless AML total hip arthroplasty in young patients.

A retrospective study was undertaken of the radiographic and clinical results and complications of 52 cementless (AML) total hip arthroplasties in 52 patients with a mean age of 48.3 years. The follow-up ranged from 9 to 12 years with a mean of 10.5 years. Of the patients, 88% had good or excellent results. Forty-two patients (81%) complained of anterior thigh pain at 3 months after surgery when weight bearing was allowed. The pain continued for a mean period of 4.3 months. In 4 patients (8%), this pain persisted after the first postoperative year. Calcar resorption was seen in 21 patients (40%), and 16 patients (31%) showed clinically insignificant heterotopic ossification. Four patients required revisions: 1 for acetabular loosening, 1 for persistent thigh pain, and 2 for massive osteolysis of the proximal femur. There were no dislocations, infections, thromboembolic events, or neurologic injuries.

Intraoperative pacemaker dysfunction caused by the use of electrocautery during a total hip arthroplasty.

Pacemaker dysfunction encountered during orthopedic procedures is a rare but potentially life-threatening complication. With an increasing number of orthopedic procedures performed on the aging population, it is not uncommon to encounter patients with pacemakers requiring major orthopedic intervention. Most, if not all, major orthopedic procedures performed today require the use of electrocautery for hemostasis. In this article we review the literature for pacemaker complications and report a case of pacemaker failure after a single use of the unipolar electrocautery on a patient undergoing a total hip replacement.

Osteolysis after Charnley primary low-friction arthroplasty. A comparison of two matched paired groups.

We reviewed 249 consecutive Charnley primary low-friction arthroplasties in 191 patients performed by one surgeon using a transtrochanteric approach at a minimum follow-up of ten years. Of these, 37 hips in 32 patients showed osteolysis and were compared with 41 hips in 37 matched patients with no osteolysis. We assessed in each case the wear rate, stability of the prosthesis, acetabular angle, socket angle, thickness of the acetabular and femoral cement mantle, canal flare index, femoral score, stem alignment, implant:canal ratio and stem:canal ratio. We found that a high rate of wear, component instability and osteolysis were associated. Osteolysis was three times more common in men than in women. Factors which reduced osteolysis were cement mantles of 6 mm at the acetabulum and of 3 mm in all zones of the femur, a stem:canal ratio of 60% to 70% and an implant:canal ratio of over 99%. The overall incidence of osteolysis was 14.9% but when these technical criteria were met, the incidence was 5.2%. This suggests that careful technique can dramatically reduce the risk of this complication.

Neurologic injury in the upper extremity after total hip arthroplasty.

The results of 7150 consecutive primary and revision total hip arthroplasties performed between 1976 and 1990 were reviewed retrospectively. Sixteen upper extremity neurologic palsies were identified in 16 patients. The incidence of upper extremity nerve palsies after total hip arthroplasty was 0.22%. There were five men and 11 women (average age, 59.5 years; range, 27-81 years). The neurologic injuries consisted of 10 ulnar palsies, four brachial plexopathies, one axillary nerve palsy, and one median nerve palsy. Patients were evaluated with respect to age, gender, preoperative diagnosis, type of procedure (primary versus revision), and surgical approach. Preoperative diagnoses included: inflammatory arthritis (11), osteoarthritis (two), avascular necrosis (one), developmental dysplasia of the hip (one), and posttraumatic arthritis (one). Fourteen of 16 patients (88%) had complete recovery. Two patients (12%) had persistent symptoms despite operative intervention. The only significant predisposing factor to developing an upper extremity neurologic injury after total hip arthroplasty was the preoperative diagnosis of an inflammatory arthropathy. Upper extremity neurologic injuries after total hip arthroplasty are rare. Patients with the preoperative diagnosis of an inflammatory arthropathy are at greater risk for experiencing upper extremity neurologic injury. The prognosis is favorable, with 88% of patients having complete recovery. Cautious induction of anesthesia and careful attention to patient positioning in the perioperative, intraoperative, and postoperative period are essential to help minimize the incidence of neurologic injuries in the upper extremity after total hip arthroplasty.

Trochanteric osteotomy and wire fixation: a comparison of 2 techniques.

Between 1986 and 1989, 190 patients (214 hips) with the diagnosis of osteoarthritis or posttraumatic arthritis underwent cemented Charnley total hip replacement surgeries via the biplane or single plane transtrochanteric approach. The technique of surgery was identical in every aspect except for the technique of the trochanteric osteotomy and reattachment. The results indicate that there was no significant difference in union rates between the 2 groups. Six (6.4%) patients in the biplane group and 7 (6.2%) patients in the single plane group had obvious evidence of nonunion at the 1-year evaluation. This study suggests no significant difference in union rate between a group of patients with biplane osteotomy and a closely paired group of patients with single plane osteotomy. Other equally important factors also may influence the rate of union of the trochanter in total hip arthroplasty.

Supracondylar femoral osteotomies for the correction of angular deformity about the knee in children. A follow-up study.

The results of 18 supracondylar osteotomies of the femur performed for angular deformity about the knee joint on 14 patients under the age of 18 years were reviewed. The mean follow-up was 46 months. Twelve of 18 osteotomies had a successful outcome. Six were considered failures due to recurrence of angular deformity despite bony union at the osteotomy site. Four of the six failures occurred in patients with metabolic bone disease. Special care needs to be taken when planning supracondylar osteotomies in patients with metabolic disease.

Peripheral neuropathies following total hip arthroplasty.

The authors reviewed the complication records following total hip arthroplasty at their institution between January 1976 and July 1989. Forty-two patients (12 men and 30 women) with 45 neurologic complications were identified following 7,133 consecutive total hip arthroplasties; an incidence rate of 0.63%. The average age of these patients was 58 years (range, 27-81 years). Thirty-four nerve injuries were noted in the lower extremity (0.48% incidence rate) and 11 in the upper extremity (0.15% incidence rate). The majority of patients (64%) with neurologic injury to the upper extremity had the diagnosis of inflammatory arthritis. The common peroneal was most often involved in the lower extremity. The ulnar nerve was most commonly involved in the upper extremity. The pathogenetic factors leading to neurologic injury in the majority of patients were not clearly established. Leg lengthening did not seem to be a major cause. The prognosis of patients with nerve palsy of the upper extremity is favorable compared with injury to the lower extremity. Similarly, the percentage of patients with a permanent neurologic deficit was lower in the primary surgery group (27%) compared with the revision/reoperation group (43%). The overall percentage of permanent nerve palsy was 33%. Female patients, for unclear reasons, appear to have a higher risk for neurologic injury. Also, the risk of neurologic injury following total hip arthroplasty appears to be higher with revisions/reoperations and with an inexperienced surgeon.

Postoperative sciatic and femoral nerve palsy with reference to leg lengthening and medialization/lateralization of the hip joint following total hip arthroplasty.

The radiographs and prospective records of 1284 (1152 primary and 135 revisions) Charnley low friction arthroplasties performed by one surgeon were studied in reference to postoperative elongation of the limb and lateralization or medialization of the center of rotation of the hip joint and their effect on postoperative nerve palsy. Displacement of the center of the hip joint in relation to fixed points on the pelvis was measured. In primary low friction arthroplasties, leg lengthening ranged from 0.4 to 4 cm; in the revision group, they ranged from 0.04 to 5.8 cm. Sixty-six hips were lengthened more than 2 cm. The center of rotation of the hip was lateralized in 18.1% of cases and medialized in 61.9%. A single case of postoperative sciatic nerve palsy (the result of laceration of the sciatic nerve at surgery) was identified. These study results indicate that nerve injuries after total hip arthroplasty may be caused by local insult, and may not be related to elongation of the limb or postoperative alteration of the center of rotation of the hip.

Intrapelvic migration of total hip prostheses. Operative treatment.

We describe a safe operative approach for removal of a prosthesis that has migrated into the pelvis, and we recommend that a two-stage reconstruction be done when revising the total hip-replacement arthroplasty. The first stage consists of the removal of the femoral component and cement through a lateral transtrochanteric approach, followed by removal of the acetabular component through an abdominal-retroperitoneal approach to permit exposure of the major intrapelvic structures and to ascertain their relationship to the acetabular component and cement. After the acetabular component has been removed, bone grafts are applied to the pelvis. Postoperatively, the patient is placed in traction for a time and then is allowed to walk with non-weight-bearing. The second stage of reconstruction, consisting of hip replacement, is performed nine to twelve months after the first stage. A satisfactory result was obtained in the four patients for whom we followed this operative regimen. In one patient, the first-stage procedure yielded a satisfactory result and the second stage was not done.

The use of somatosensory evoked potential during revision or reoperation for total hip arthroplasty.

Somatosensory evoked potential (SSEP) was used to continuously monitor the sciatic nerve intraoperatively during revision or reoperation for total hip arthroplasty. Of 25 cases monitored, eight patients (32%) exhibited 12 instances of SSEP deterioration, indicating neurologic compromise. These neurologic problems were due to retraction in seven cases and limb positioning in five. No postoperative neurologic deficits were noted in this group. Two of 35 patients (5.7%) not monitored had postoperative neurologic deficits. SSEP monitoring is a useful method for minimizing the intraoperative risks of clinical neurologic deficits during revisions or difficult reoperations.

Cartilaginous exostosis arising from the ventral surface of the scapula. A case report.

Osteochondromas of the scapula are not rare in occurrence, especially in multiple hereditary exostosis. A scapular exostosis, excised from the ventral surface of the scapula in a 13-year-old girl, produced symptoms of shoulder pain.

Incidence and mechanism of failure of cemented acetabular component in total hip arthroplasty.

Clinical results today seem to suggest that acrylic cement is crucial in producing immediate and reproducible results of pain-free joints following total hip replacement. Proper application by the use of contemporary techniques may be suitable in most conditions requiring hip replacement. The incidence of acetabular failure in a specific group of patients at risk may warrant experimentation by the use of a noncemented system. The mechanism of failure of low-friction arthroplasty may be multifaceted, but our experience indicates that the mechanisms of failure of the acetabulum have been due to excessive deepening and expansion of the acetabulum, once thought to be fundamental to the procedure. A rudimentary technique of cement pressurization, both in the femur and in the acetabulum, also may have played a part in late failures of this procedure. Early demarcation at the cement-bone interface was prevalent in young and active or heavy individuals. Demarcation and loosening were time-dependent phenomena. Demarcation and loosening also appeared with the aging process and increased osteopenia. A higher incidence of loosening also was observed in young and light-weight individuals, with presumably increased elasticity of the pelvic bone.