French Hip & Knee Society classification of short-stem hip prostheses: Inter- and intra-observer reproducibility.

INTRODUCTION: In total hip replacement (THR), a short stem theoretically provides more physiological force transfer to the proximal femur, conserves bone stock and facilitates minimally invasive surgery. On the other hand, such implants involve a learning curve and incur risk of malpositioning or fracture and of secondary mobilization. There are several types of short stem, and classification is needed. Classifications exist, but are based more on implant length than on anchorage zone, and most have not been tested for reproducibility. The French Hip & Knee Society (SFHG) developed a short-stem classification based on anchorage zone inside the femur. The objectives of the present study were: (1) to present the classification, (2) to apply it to the short-stem models available in France and those widely used worldwide, and (3) to assess reproducibility. HYPOTHESIS: The SFHG short-stem classification enables reproducible comparison. MATERIAL AND METHOD: A short-stem classification according to anchorage zone was drawn up by an expert group. The stems and the classification were presented to 12 surgeons performing THR, who classified the stems according to the classification; a retest was performed 2 months later. RESULTS: The classification is based on femoral stem anchorage site, in 5 types: type 1, cephalic; type 2, isolated cervical; type 3, Calcar femorale; type 4, metaphyseal; and type 5, conventional metaphyseal-diaphyseal, with shortened stems. Inter-observer reproducibility was 92.7% [95%CI: 91.7%-93.6%], with kappa 0.785 [95%CI: 0.755-0.814], and Lin test-rest concordance correlation coefficient 0.852 [95%CI: 0.836-0.869]. Intra-observer reproducibility was 94.0% [95%CI: 91.9%-96.1%], with kappa 0.820 [95%CI: 0.759-0.882], and Lin test-retest concordance correlation coefficient 0.820 [95%CI: 0.792-0.849]. DISCUSSION: This new classification enables femoral implants to be reproducibly compared according to anchorage zone. LEVEL OF EVIDENCE: IV; retrospective study without control group.

Reduced Chlorine in Drinking Water Distribution Systems Impacts Bacterial Biodiversity in Biofilms.

In drinking water distribution systems (DWDS), a disinfectant residual is usually applied to limit bacterial regrowth. However, delivering water with no or reduced chlorine residual could potentially decrease the selection for antimicrobial resistant microorganisms, favor bacterial regrowth and result in changes in bacterial populations. To evaluate the feasibility of water reduction in local DWDS while ensuring water safety, water quality was measured over 2 months in two different networks, each of them harboring sub-areas with normal and reduced chlorine. Water quality remained good in chlorine reduced samples, with limited development of total flora and absence of coliforms. Furthermore, 16S rRNA amplicon-based metagenomics was used to investigate the diversity and the composition of microbial communities in the sub-networks. Taxonomic classification of sequence reads showed a reduced bacterial diversity in sampling points with higher chlorine residuals. Chlorine disinfection created more homogeneous bacterial population, dominated by Pseudomonas, a genus that contains some major opportunistic pathogens such as P. aeruginosa. In the absence of chlorine, a larger and unknown biodiversity was unveiled, also highlighted by a decreased rate of taxonomic classification to the genus and species level. Overall, this experiment in a functional DWDS will facilitate the move toward potable water delivery systems without residual disinfectants and will improve water taste for consumers.

Exchangeable Femoral Neck (Dual-Modular) THA Prostheses Have Poorer Survivorship Than Other Designs: A Nationwide Cohort of 324,108 Patients.

BACKGROUND: Exchangeable neck stems, defined as those with a dual taper (that is, a modular junction between the femoral head and the femoral neck and an additional junction between the neck and the stem body), were introduced in THA to improve restoration of joint biomechanics (restoring anteversion, offset, and limb length) and reduce the risk of dislocation. However exchangeable necks have been reported to result in adverse effects such as stem fractures and acute local tissue reaction. Whether they result in a net improvement to or impairment of reconstructive survivorship remains controversial. QUESTIONS/PURPOSES: (1) To compare the prosthetic survivorship and all-cause revision risk of exchangeable femoral neck THAs versus fixed neck THAs, taking known prosthetic revision risk factors into account; and (2) to compare the cause-specific revision risk of exchangeable femoral neck THAs versus fixed neck THAs, adjusting for known prosthetic risk factors. METHODS: Using French national health-insurance databases, we identified all French patients older than 40 years who underwent primary THA from 2009 through 2012. To ensure accuracy of the data, we considered only beneficiaries of the general insurance scheme (approximately 77% of the population). Characteristics of the prosthesis and the patients receiving an exchangeable femoral neck THA were compared with those receiving a fixed femoral neck THA (defined as femoral stem with only the head being exchangeable). Revision was the event of interest. Followup started on the date the THA was performed, until the patient experienced revision, died, was lost to followup, or until the followup period ended (December 31, 2014), whichever came first. Competing risk THA survivorship was calculated and compared (purpose 1), as were cause-specific Cox regression models (purpose 2). The study cohort included 324,108 individuals with a mean age of 77 years. A total of 24% underwent THA for acute trauma, and 3% of the group received an exchangeable neck THA. During the median 45-month followup (mean, 42 months; minimum, 1 day; maximum, 6 years), 11,968 individuals underwent prosthetic revision. RESULTS: The cumulative revision incidence was 6.5% (95% CI, 5.8%-7.3%) for exchangeable neck THAs versus 4.7% (95% CI, 4.6%-4.8%) for fixed neck THAs (p < 0.001). After controlling for potential confounding variables including age, sex, comorbidities, indication for THA, cementation, bearing surface, and the characteristics of the center where the implantation was performed, we found that the exchangeable femoral neck THA was associated with an increased hazard ratio (HR) of revision of 1.26 (95% CI, 1.14-1.38; p < 0.001) compared with the fixed neck THA. When dealing with cause-specific revision, exchangeable neck THAs had a higher incidence of revision for implant failure or periprosthetic fracture, and for mechanical complications; adjusted HRs were, respectively, 1.68 (95% CI, 1.24-2.27; p < 0.001) and 1.27 (95% CI, 1.13-1.43; p < 0.001), for exchangeable neck THAs compared with fixed ones. CONCLUSIONS: Exchangeable neck THAs had poorer survivorship independent of other prosthetic revision risk factors. Accordingly, expected anatomic and functional benefits should be carefully assessed before choosing this design. LEVEL OF EVIDENCE: Level III, therapeutic study.

Association Between Total Hip Replacement Characteristics and 3-Year Prosthetic Survivorship: A Population-Based Study.

IMPORTANCE: Total hip replacement (THR) is successful in treating hip arthritis. Prosthetic survivorship may depend on characteristics of the implant, notably THR fixation technique and bearing surface type. OBJECTIVE: To compare THR short-term survivorship according to cement type and bearing surface. DESIGN, SETTING, AND PARTICIPANTS: The cohort included all French patients aged 40 years or older covered by the general scheme of the French national health insurance system who had undergone THR from April 1, 2010, through December 31, 2011, for arthritis, according to French national health insurance databases. The cohort was followed up until December 31, 2013. The THR survivorship was assessed according to cement type and bearing surface in univariate and multivariate Cox proportional hazards regression models adjusted for patient and implanting center characteristics. EXPOSURES: Antibiotic-free cemented THRs and antibiotic-impregnated cemented THRs were compared with uncemented THRs. Ceramic-on-ceramic (CoC), ceramic-on-polyethylene (CoP), and metal-on-metal (MoM) THRs were compared with metal-on-polyethylene (MoP) THRs. MAIN OUTCOMES AND MEASURES: Revision, including any surgical reintervention in which the implant or any of its components was changed or removed. RESULTS: The study cohort comprised 100 191 individuals: mean age at baseline, 69.5 years; women, 56.6%; uncemented THR, 74.8%; antibiotic-free cemented THR, 3.8%; antibiotic-impregnated cemented THR, 21.4%; CoC, 40.9%; MoP, 33.9%; CoP, 20.8%; and MoM, 4.4%. During the median 33-month follow-up period, 3142 individuals underwent prosthetic revision. Antibiotic-impregnated cemented THRs had a better prognosis than uncemented THRs: cumulative revision rates were 2.4% and 3.3%, respectively (P < .001), and the multivariate adjusted hazard ratio was 0.75 (95% CI, 0.67-0.84; P < .001). This association was particularly significant in women. The CoP and CoC THRs were no different from the MoP THR. The MoM THR had slightly shorter survivorship compared with the MoP THR (adjusted hazard ratio, 1.20; 95% CI, 1.01-1.43; P < .001). CONCLUSIONS AND RELEVANCE: Characteristics of THR are related to early prosthetic revision: antibiotic-impregnated cemented THRs have a better prognosis and MoM THRs a worse one. These findings are useful in helping surgeons select a THR fixation technique and helpful for both patient and surgeon in the decision-making process.

Are gender-specific femoral implants for total knee arthroplasty necessary?

The purpose of this study was to determine the effect of gender on epiphyseal morphology and using this information to determine if an implant product line with a single width provides sufficient bone coverage for the entire population of knees being replaced. Morphology of the distal femoral epiphysis from 420 continuous knees was acquired with a surgical navigation system during primary TKA. A three-dimensional model of the distal femur was generated and used to determine the anterioposterior (AP) and mediolateral (ML) dimensions on 19 different virtual knee sections. Female knees had smaller AP and ML dimensions than male knees. The ML width of the distal femoral epiphysis was associated with femur length, not gender. Measurements derived from surgical navigation confirm that distal femoral epiphysis dimensions are related to femur length only independently of gender.

Rotational alignment of the femoral component using trochlear navigation during total knee arthroplasty: a dual-center study of 145 cases.

Rotational alignment of the femoral component during TKA is critical. Here we propose a technique using navigation of the femoral trochlea to determine the rotation of the femoral component. The rotation is considered "ideal" when the component position leads to the arthroplasty trochlea being perfectly superimposed over the native trochlea. Thus the arthroplasty trochlea will be aligned on the trochlear groove axis, which itself is perpendicular to the transepicondylar axis. This was a prospective, non-randomized, dual-center study involving 145 knees. In all knees, the rotation of the femoral component was determined intraoperatively by trochlear navigation. The alpha angle obtained with this method was compared to the one calculated on a preoperative or postoperative CT scan. There was excellent agreement between the results obtained with the CT scan method and the ones obtained with trochlear navigation.

Genetic analysis of glycopeptide-resistant Staphylococcus epidermidis strains from bone and joint infections.

Glycopeptide-resistant Staphylococcus epidermidis (GRSE) strains are of increasing concern in bone and joint infections (BJIs). Using multilocus sequence typing and multilocus variable-number tandem repeat analysis, we show that BJI-associated GRSE strains are genetically diverse but arise from related, multiresistant hospital sequence types (STs), mostly ST2, ST5, and ST23.

Can hip anatomy be reconstructed with femoral components having only one neck morphology? A study on 466 hips.

This extensive radiographic study asks if there is a statistical relationship between the size of the stem that will best fit the femur and the vertical and lateral offsets of the reconstructed acetabular center, what is the distribution of vertical and lateral offsets in this large and if there is a statistical difference among surgeons in the planned location of the reconstructed acetabular center. On 466 radiographs, five surgeons separately templated stem size and acetabular cup location. The vertical and horizontal coordinates of the reconstructed acetabulum center were measured relative to the planned position of the stem. We found a strong correlation between the stem size and the average lateral and vertical offsets. Acetabular reaming associated with the anatomic variability of native femoral necks, leads to a span of 36 mm in lateral offset, and a span of 39 mm in vertical offset. Statistically significant differences were also found in the way surgeons plan acetabular reaming.

Decreased susceptibility to teicoplanin and vancomycin in coagulase-negative Staphylococci isolated from orthopedic-device-associated infections.

We studied 315 coagulase-negative Staphylococcus strains recovered prospectively during 240 surgical procedures (206 subjects) from proven or suspected device-associated bone and joint infections. Sixteen strains (5.1%) had decreased susceptibility to glycopeptides: 15 (12 S. epidermidis strains, 2 S. capitis strains, and 1 S. haemolyticus strain) to teicoplanin alone (MIC of 16 mg/liter, n = 9; MIC of 32 mg/liter, n = 6) and one (S. epidermidis) to both teicoplanin and vancomycin (MIC, 16 and 8 mg/liter, respectively). Decreased susceptibility to teicoplanin was more prevalent in "infecting" strains (i.e., strains recovered from >/=2 distinct intraoperative samples) than in "contaminants" (i.e., strains not fulfilling this criterion) (8.1% [12/149] versus 2.4% [4/166], respectively [P = 0.022]). One hundred percent (13/13) of S. epidermidis strains with decreased susceptibility to teicoplanin were resistant to methicillin (versus 112/173 [64.7%] for S. epidermidis strains susceptible to teicoplanin; P = 0.021).

Gardnerella vaginalis acute hip arthritis in a renal transplant recipient.

We report the case of an acute hip septic arthritis caused by Gardnerella vaginalis in a 48-year-old woman under immunosuppressive therapy for kidney transplantation. After surgical resection of the hip and 6 weeks of combination antibiotic therapy, a total hip prosthesis was successfully implanted with no recurrence after 4 years.

Antiinflammatory effect of peripheral nerve blocks after knee surgery: clinical and biologic evaluation.

BACKGROUND: Nerve blocks provide analgesia after surgery. The authors tested whether nerve blocks have antiinflammatory effects. METHODS: Patients had combined sciatic (single-shot) and continuous femoral block (48 h) (block group) or morphine patient-controlled analgesia after total knee arthroplasty. Pain at rest and upon movement was monitored at 1 (D1), 4 (D4), and 7 days (D7) and 1 (M1) and 3 months (M3) after surgery. Knee inflammation was evaluated (skin temperature, knee circumference) before surgery and at D1, D4, D7, M1, and M3. Plasma cytokine concentrations (interleukin [IL]-6, IL-1beta, tumor necrosis factor [TNF], IL-10, soluble receptor 1 of TNF [sTNF-R1]) were measured before surgery and at 4 h, D1, D4, and D7 after surgery. Capsule and synovial membrane cytokines were measured (IL-6, TNF, IL-1, IL-10). Knee flexion was evaluated before surgery and at D1, D4, D7, M1, and M3. Morphine use and recovery time to autonomy were monitored. RESULTS: Pain at rest and upon movement was lower in the block group than in patient-controlled analgesia patients between D1 and D7 (analysis of variance, P < 0.005). Knee flexion was improved in the block group for D1 to M1 (analysis of variance, P < 0.0001). Block group patients recovered nonassisted mobilization (t test, P = 0.04) and toilet use (t test, P = 0.03) more rapidly. Knee circumference and skin temperature were lower in the block group between D1 and D7 (analysis of variance, P < 0.05). Synovial membrane IL-1 (P < 0.05) and IL-10 (P < 0.01) increased, and plasma IL-6 and sTNF-R1 peaked at 24 h, with no difference between groups. CONCLUSION: Nerve blocks inhibited clinical inflammation after total knee arthroplasty, with no change in tissue and plasma cytokine concentrations.

Ankle replacement versus arthrodesis: a comparative gait analysis study.

BACKGROUND: The improving survivorship of ankle replacements is making this an increasingly popular option in the treatment of ankle arthritis, rather than the established option of ankle fusion. The potential benefits of restoring movement, improving gait and protecting adjacent joints are persuasive arguments in favor of replacing rather than fusing the ankle joint. METHODS: Gait analysis was performed before and after ankle arthroplasty on 12 patients, and compared to 12 patients with a successful ankle arthrodesis and to a healthy control group of 12 people. RESULTS: Important differences between the arthrodesis and ankle replacement groups were demonstrated although neither restored normal movement or walking speed. Ankle arthrodesis resulted in a faster gait with a longer step length compared to replacement, although the timing of gait demonstrated greater asymmetry. The ankle replacement group had greater movement at the ankle, a symmetrical timing of gait and restored ground reaction force pattern. CONCLUSION: The improved timing of gait would support the observation of a reduction in limp with ankle replacement though the gait is significantly slower. Longer term results are necessary to determine whether the improved movement and force transmission persists with time and protects adjacent articulations.

Acetabular reconstruction in revision hip surgery using femoral head block allograft.

This prospective study analyzed the clinical and radiological results of 140 consecutive cases of acetabular revision using large frozen femoral head allografts and cemented all-polyethylene acetabular components. Mean follow-up was 10 years (range: 5-16 years). Thirty patients died, seven were lost to follow-up, and 26 had failed and undergone further surgery. Nineteen failures were due to aseptic failure and collapse of the graft. Kaplan-Meier survival analysis calculated a mean survival at 10 years of 88.5% for revision for any reason. We compared all reported techniques of acetabular reconstruction for similar defects and recommend a surgical strategy based on the available evidence, but weighted towards a preference to reconstitute bone stock rather than removing further bone in the revision situation.

Kinetics and mechanisms of formation of bromophenols during drinking water chlorination: assessment of taste and odor development.

Halophenols are often reported as off-flavor causing compounds responsible for medicinal taste and odor episodes in drinking water. To better understand and minimize the formation of 2-bromophenol and 2,6-dibromophenol which have low odor threshold concentrations (OTCs, 30 and 0.5 ng/L, respectively) a kinetic data base for the chlorination and bromination of phenols was established by combination of kinetic measurements and data from literature. Second-order rate constants for the reactions of chloro- and bromophenols with chlorine and bromine were determined over a wide pH range. The second-order rate constants for bromination of phenols are about three orders of magnitude higher than for chlorination. A quantitative structure activity relationship (QSAR) showed a good comparability of second-order rate constants from this study with those published previously for different phenol derivatives. The quantification of product distribution of the formed halophenols demonstrated that chlorine or bromine attack in ortho position is favored with respect to the para position. A kinetic model was formulated allowing us to investigate the influence of chlorine dose and some water quality parameters such as the concentration of phenol, ammonia, bromide and the pH on the product distribution of halophenols. The kinetic model can be applied to optimize drinking water chlorination with respect to phenol-born taste and odor problems. In general, high chlorine doses lead to low concentrations of intermediate odorous chlorophenols and bromophenols. An increase in the ammonia or phenol concentration leads to a higher consumption of HOCl and therefore greater final concentration of intermediate bromophenols. The presence of higher bromide than phenol concentration also facilitates the rapid bromination pathway which leads to further bromination of 2,6-dibromophenol to higher brominated phenols. Laboratory-scale experiments on taste and odor formation due to the chlorination of phenol- and bromide-containing waters have confirmed the trend of the model calculations.

Acetabular component revision with frozen massive structural pelvic allograft: average 5-year follow-up.

We evaluated the use of a hemipelvic acetabular transplant in 20 revision hip arthroplasties with massive acetabular bone defects. We report 65% good intermediate-term results at a mean follow-up of 5 years (4-10 years). A cemented cup (without a reinforcement ring) was entirely supported by the allograft in all procedures. There were 7 failures (5 aseptic loosening and 2 deep infections). Two dislocations occurred but did not require acetabular revision. There were 2 cases in which moderate acetabular migration occurred but then stabilised and did not progress. Thirteen of 20 acetabular reconstructions did not require revision. We believe that these are satisfactory intermediate-term results for massive acetabular defects too large for reconstruction with other standard techniques.