Kinematic alignment of medial UKA is safe: a systematic review.

PURPOSE: Owing to the improved understanding of knee kinematics and the successful introduction of the kinematic alignment (KA) technique for implanting total knee arthroplasty (TKA), it was recently understood that the "Cartier angle technique" corresponds to a kinematic implantation of the uni-compartmental knee arthroplasty (UKA) components. When compared to the universally spread mechanical alignment (MA) technique for implanting UKA, the KA method generates a more anatomic prosthetic knee that may be clinically advantageous. The aims of this study are to determine if KA UKAs are associated with acceptable functional performance and patient satisfaction (question 1), rates of residual pain and tibia plateau fracture (question 2), and rates of reoperation and revision (question 3), and to define the component orientation and limb alignment as measured on radiograph (question 4), and the stress shielding related bone loss in the proximal tibia (question 5) with KA UKA, and where possible to compare with MA UKA. STUDY HYPOTHESIS: KA UKA generates good clinical outcomes, similar or superior to the ones of MA UKA. METHOD: Systematic review of literature databases were primarily searched using Healthcare Databases Advanced Search (HDAS). Two primary searches were conducted using the electronic databases MEDLINE, EMBASE, and PubMed, and a secondary search was conducted using review articles and bibliography of obtained papers in order to ascertain more material. RESULTS: Nine eligible non-comparative prospective (3) or retrospective (6) cohort studies, which cumulated 593 KA UKAs with follow-up between 3.2 and 12 years, fulfilled the inclusion criteria for this systematic review. The findings demonstrated high Knee Society Score (KSS) (from 87 to 95) and function scores (from 81 to above 91) in addition to patient satisfaction scores of 88%. There was no revision for tibia plateau fracture, 0.8% (5 cases) for unexplained pain tibia, 2.0% (12 cases) for component loosening, and 5.6% (33 cases) for any causes of aseptic failures reported for KA UKA. The prosthetic lower limb and tibia implant alignments were both found to be in slight varus (means between 3 and 5°), and the postoperative joint line and tibia component was shown to be parallel to the floor when standing. The KA UKA components migration, as measured on radiostereometry, was acceptable. DISCUSSION/CONCLUSION: The KA technique is an alternative, personalised, more physiological method for implanting UKA, which could be clinically advantageous when compared to the MA technique. The literature supports the good mid- to long-term clinical safety and good efficacy of KA UKA; however, comparison between KA and MA techniques for UKA was not performed due to limited literature. Further investigations are needed to better define the clinical impact of KA UKA, and the acceptable limits for KA of the UKA tibial component. LEVEL OF EVIDENCE: Level 4; systematic review of level 4 studies.

Distribution of Escherichia coli O157:H7 in ground beef: Assessing the clustering intensity for an industrial-scale grinder and a low and localized initial contamination.

Undercooked ground beef is regularly implicated in food-borne outbreaks involving pathogenic Shiga toxin-producing Escherichia coli. The dispersion of bacteria during mixing processes is of major concern for quantitative microbiological risk assessment since clustering will influence the number of bacteria the consumers might get exposed to as well as the performance of sampling plans used to detect contaminated ground beef batches. In this study, batches of 25kg of ground beef were manufactured according to a process mimicking an industrial-scale grinding with three successive steps: primary grinding, mixing and final grinding. The ground beef batches were made with 100% of chilled trims or with 2/3 of chilled trims and 1/3 of frozen trims. Prior grinding, one beef trim was contaminated with approximately 106-107CFU of E. coli O157:H7 on a surface of 0.5cm2 to reach a concentration of 10-100cells/g in ground beef. The E. coli O157:H7 distribution in ground beef was characterized by enumerating 60 samples (20 samples of 5g, 20 samples of 25g and 20 samples of 100g) and fitting a Poisson-gamma model to describe the variability of bacterial counts. The shape parameter of the gamma distribution, also known as the dispersion parameter reflecting the amount of clustering, was estimated between 1.0 and 1.6. This k-value of approximately 1 expresses a moderate level of clustering of bacterial cells in the ground beef. The impact of this clustering on the performance of sampling strategies was relatively limited in comparison to the classical hypothesis of a random repartition of pathogenic cells in mixed materials (purely Poisson distribution instead of Poisson-gamma distribution).

Prevalence of carriage of Shiga toxin-producing Escherichia coli serotypes O157:H7, O26:H11, O103:H2, O111:H8, and O145:H28 among slaughtered adult cattle in France.

The main pathogenic enterohemorrhagic Escherichia coli (EHEC) strains are defined as Shiga toxin (Stx)-producing E. coli (STEC) belonging to one of the following serotypes: O157:H7, O26:H11, O103:H2, O111:H8, and O145:H28. Each of these five serotypes is known to be associated with a specific subtype of the intimin-encoding gene (eae). The objective of this study was to evaluate the prevalence of bovine carriers of these "top five" STEC in the four adult cattle categories slaughtered in France. Fecal samples were collected from 1,318 cattle, including 291 young dairy bulls, 296 young beef bulls, 337 dairy cows, and 394 beef cows. A total of 96 E. coli isolates, including 33 top five STEC and 63 atypical enteropathogenic E. coli (aEPEC) isolates, with the same genetic characteristics as the top five STEC strains except that they lacked an stx gene, were recovered from these samples.O157:H7 was the most frequently isolated STEC serotype. The prevalence of top five STEC (all serotypes included) was 4.5% in young dairy bulls, 2.4% in young beef bulls, 1.8% in dairy cows, and 1.0% in beef cows. It was significantly higher in young dairy bulls (P<0.05) than in the other 3 categories. The basis for these differences between categories remains to be elucidated. Moreover,simultaneous carriage of STEC O26:H11 and STEC O103:H2 was detected in one young dairy bull. Lastly, the prevalence of bovine carriers of the top five STEC, evaluated through a weighted arithmetic mean of the prevalence by categories, was estimated to 1.8% in slaughtered adult cattle in France.

Fixed- versus mobile-bearing UKA: a systematic review and meta-analysis.

PURPOSE: Two design concepts are currently used for unicondylar knee arthroplasty (UKA) prostheses: fixed bearing (FB) and mobile bearing (MB). While MB prostheses have theoretical advantages over their FB counterparts, it is not clear whether they are associated with better outcomes. A systematic review was conducted to examine survivorship differences and differences in failure modes of between FB and MB designs. METHODS: PubMed, Scirus and Cochrane library databases were searched for medial UKA outcome studies. A total of 44 papers, involving 9,463 knees, were eligible. Outcomes examined included knee function, survivorship and the reasons for, and incidence of, revision for FB and MB prostheses. Random effects meta-analysis was employed to obtain pooled revision rate estimates. Where available, cause-specific time to revision was extracted. RESULTS: Mean follow-up was 8.7 years for FB and 5.9 years for MB prostheses. There were no other relevant baseline differences. The overall crude revision rate for FB and for MB prostheses was 0.90 (95 % confidence interval (CI) 0.65-1.21) and 1.51 (95 % CI 1.11-1.93) per 100 component years, respectively. After stratification on follow-up time and age, the revision rates were not substantially different, aside for younger patients in short term from studies with short-term follow-up. CONCLUSION: No essential differences between the two designs were observed. MB and FB UKA designs have comparable revision rates. As our study is based on predominantly observational data, with large variations in reporting standards, inferences should be drawn with caution. LEVEL OF EVIDENCE: IV.

Cost-effectiveness of unicondylar versus total knee arthroplasty: a Markov model analysis.

BACKGROUND: Unicondylar knee arthroplasty (UKA) is believed to lead to less morbidity and enhanced functional outcomes when compared with total knee arthroplasty (TKA). Conversely, UKA is also associated with a higher revision risk than TKA. In order to further clarify the key differences between these separate procedures, the current study assessing the cost-effectiveness of UKA versus TKA was undertaken. METHODS: A state-transition Markov model was developed to compare the cost-effectiveness of UKA versus TKA for unicondylar osteoarthritis using a Belgian payer's perspective. The model was designed to include the possibility of two revision procedures. Model estimates were obtained through literature review and revision rates were based on registry data. Threshold analysis and probabilistic sensitivity analysis were performed to assess the model's robustness. RESULTS: UKA was associated with a cost reduction of €2,807 and a utility gain of 0.04 quality-adjusted life years in comparison with TKA. Analysis determined that the model is sensitive to clinical effectiveness, and that a marginal reduction in the clinical performance of UKA would lead to TKA being the more cost-effective solution. CONCLUSION: UKA yields clear advantages in terms of costs and marginal advantages in terms of health effects, in comparison with TKA.

Tricompartmental resurfacing arthroplasty with a follow-up of more than 30 years.

BACKGROUND: Unicompartmental and patellofemoral joint replacements are proven solutions for arthritis limited to one compartment of the knee. Bicompartmental replacement has been considered lately as an alternative for combined medial and patellofemoral arthritis. The main idea behind these resurfacing solutions is tissue preservation with conservation of bone stock and both cruciate ligaments. Tricompartmental replacement with selective resurfacing of all three compartments with different modular implants is exceptional. METHODS: The authors present a case with more than thirty year follow-up both clinically and radiographically. RESULTS: Excellent function and patient satisfaction are observed at 30 year follow-up. Radiographs show no osteolysis or loosening of components. CONCLUSIONS: Conservation of both anterior and posterior cruciate ligaments seems to protect against polyethylene wear at long-term follow-up. LEVEL OF EVIDENCE: IV.

Intimin gene (eae) subtype-based real-time PCR strategy for specific detection of Shiga toxin-producing Escherichia coli serotypes O157:H7, O26:H11, O103:H2, O111:H8, and O145:H28 in cattle feces.

Shiga toxin-producing Escherichia coli (STEC) strains belonging to serotypes O157:H7, O26:H11, O103:H2, O111:H8, and O145:H28 are known to be associated with particular subtypes of the intimin gene (eae), namely, γ1, ß1, ε, θ, and γ1, respectively. This study aimed at evaluating the usefulness of their detection for the specific detection of these five main pathogenic STEC serotypes in cattle feces. Using real-time PCR assays, 58.7% of 150 fecal samples were found positive for at least one of the four targeted eae subtypes. The simultaneous presence of stx, eae, and one of the five O group markers was found in 58.0% of the samples, and the five targeted stx plus eae plus O genetic combinations were detected 143 times. However, taking into consideration the association between eae subtypes and O group markers, the resulting stx plus eae subtype plus O combinations were detected only 46 times. The 46 isolation assays performed allowed recovery of 22 E. coli strains belonging to one of the five targeted STEC serogroups. In contrast, only 2 of 39 isolation assays performed on samples that were positive for stx, eae and an O group marker, but that were negative for the corresponding eae subtype, were successful. Characterization of the 24 E. coli isolates showed that 6 were STEC, including 1 O157:H7, 3 O26:H11, and 2 O145:H28. The remaining 18 strains corresponded to atypical enteropathogenic E. coli (aEPEC). Finally, the more discriminating eae subtype-based PCR strategy described here may be helpful for the specific screening of the five major STEC in cattle feces.

Survivorship of UKA in the middle-aged.

BACKGROUND: Unicompartmental knee arthroplasty (UKA) is known to be a viable procedure allowing for preservation of the intact compartments and delivering excellent function at long-term follow-up. The primary purpose of this single-surgeon study was to analyse the survivorship of a fixed bearing UKA in patients younger than 60 years. METHODS: From all UKAs implanted between 1993 and 2005 at the senior authors' centre, 223 patients <60 years at operation with a minimum follow-up of 5 years were identified including all-poly and metal-backed tibiae. They were evaluated applying the Knee Society Score (KSS) at latest follow-up. Survivorship was calculated using Kaplan-Meier analysis, which considered the following variables: gender, type of tibial implant, medial vs. lateral UKA, and age. RESULTS: Average age at index operation was mean 53.7 (SD 5.8, range 30-60) years at a mean follow-up of 10.8 (SD 3.5, range 5-17) years. From the KSS, the knee score was 94.3 (SD 7.8) and the function score was 94.9 (SD 6.8). At latest follow-up, the implant survival rate was 94.3%. Survivorship for the entire cohort was 93.5% at 10 years (medial UKA 94.1% vs. lateral 91.8%), and 86.3% at 15 years (85.1% medial vs. 91.7% lateral) CONCLUSION: In conclusion, excellent survival and function outcomes were noted in this subgroup of patients younger than 60 years. Revision rates were comparable to those studies in which UKA was performed on an elderly patient population. UKA can successfully be performed in patients younger than 60 years with appropriate patient selection.

UKA after spontaneous osteonecrosis of the knee: a retrospective analysis.

PURPOSE: Safety and efficacy of unicompartmental knee arthroplasty (UKA) in unicompartmental osteoarthritis (OA) has been shown in large patient series. It has been matter of discussion whether or not spontaneous osteonecrosis of the knee (SONK) can successfully be treated with UKA. PATIENTS AND METHODS: A retrospective approach included 52 cases of UKA for SONK of the femoral condyles. Four implants were revised (7.7%), and seven patients had died. Nine patients were interviewed by telephone, 28 followed the invitation for clinical examination including clinical scores (KSS and WOMAC) and radiographs. Satisfaction of patients was recorded in four categories. Four patients (7.7%) were lost to follow-up. RESULTS: Average follow-up was 10.9 ± 4.8 years (4-25). Average age at operation was 66.6 ± 9.7 years. The KSS score increased from a preoperative 85 ± 30 to 173 ± 27 (p < 0.0001) at latest follow-up. WOMAC was 7.7 ± 11.4 at latest follow-up. Of the patients with implants still in place, most patients were satisfied (21.6%) or very satisfied (75.7%) with the outcome of this surgical procedure. One patient was dissatisfied (2.7%). Kaplan-Meier analysis with implant revision as endpoint revealed a survival rate of 93.1% at 10 years and 90.6% at 15 years. DISCUSSION: This study shows that spontaneous osteonecrosis of the knee (SONK) can successfully be treated with UKA at a good mid- to long-term follow-up.

UKA in combination with PFR at average 12-year follow-up.

INTRODUCTION: Safety and efficacy of unicompartmental knee arthroplasty (UKA) has been shown in large patient series. Patellofemoral replacement (PFR) is known to be a viable solution to end-stage patellofemoral arthritis. Bicompartmental osteoarthritis (OA) affecting the medial tibio-femoral and the patello-femoral compartment (medio-patellofemoral OA) is often treated with total knee arthroplasty (TKA). It was hypothesized that medio-patellofemoral OA can successfully be treated with bicompartmental arthroplasty. METHOD: In a retrospective approach nine patients who had received UKA in combination with PFR were included into the study. Intact ACL and lateral compartment were conditions for the indication. Patients were clinically examined including clinical scores (KSS and WOMAC) and radiographies were evaluated. Satisfaction of patients was recorded under four categories. RESULTS: Average follow-up after bicompartmental arthroplasty was 11.8 ± 5.4 years (4-17 years). Among the nine patients there were eight females and one male at an average age at operation of 64 ± 5 years. No surgical revisions were required following bicompartmental arthroplasty. The KSS score increased from a preoperative 68.8 ± 26.2 to 175.5 ± 22.9 at latest follow-up (p = 0.002). WOMAC was 18.3 ± 8.6 at latest follow-up. All patients included were satisfied (n = 3) or very satisfied (n = 6) with the outcome of this surgical procedure. CONCLUSION: This small case series shows that a bicompartmental arthroplasty can be a successful approach to prevent or postpone TKA. However, this intervention is technically demanding and requires experience in both UKA and PFR.

Unicondylar knee arthroplasty in middle-aged patients: a minimum 5-year follow-up.

The purpose of this study was to report the results of unicompartmental knee arthroplasty in patients 60 years or younger for a period long enough to be statistically significant. In a cohort of 1173 unicompartmental knee prostheses implanted between 1991 and 2006, 161 knees from 158 patients 60 years or younger at the time of surgery who had 5 to 14 years of follow-up were reviewed. The Genesis unicompartmental knee replacement (Smith & Nephew, Memphis, Tenn) with the metal-back or full-poly design was implanted in these patients. The Knee Society score at most recent follow-up was 94.02, and average function score was 93.76. Survivorship for the entire cohort was 94.50% at 10 years and 88.48% at 12 years.

Long-term results with the first patellofemoral prosthesis.

UNLABELLED: We retrospectively reviewed 70 patients, representing 79 knees, who had isolated patellofemoral arthroplasty between 1975 and 1991 using the Richards II and III implants. Seventy-five percent of the prostheses were still functioning at a minimum of 6 and average followup of 10 years after implantation. The main cause of failure was secondary femorotibial osteoarthritic deterioration (8 knees). Only two complications of a mechanical nature related to the implant have been observed. Surgical revisions have not presented any particular difficulties. The main indication for this type of implant is advanced patellofemoral osteoarthritis secondary to a constitutional trochlear dysplasia occurring in a correctly aligned knee for which no other therapeutic procedure allows the same type of result to be achieved. LEVEL OF EVIDENCE: Therapeutic Study, Level IV (case series). See the Guidelines for Authors for a complete description of levels of evidence.