PurposeThe primary purpose of this study was to determine if isolated medial patellofemoral ligament (MPFL) reconstruction for lateral patellofemoral instability altered the patellar height ratio. Secondary purposes were to use disease‐specific quality‐of‐life scores to determine if MPFL reconstruction is as successful in patients with patella alta, compared to those without; and whether the change in the patellar height ratio after MPFL reconstruction is influenced by demographic and clinical factors. MethodsDemographic and clinical data were collected pre‐operatively on 283 patients with recurrent patellofemoral instability. Pre‐operative and 6‐month post‐operative true‐lateral radiographs were assessed to determine the patellar height ratio using the Caton‐Deschamps index. A Caton‐Deschamps index ≥ 1.2 was defined as patella alta. Paired t tests evaluated the effect of MPFL reconstruction on the Caton‐Deschamps index. Using a two‐sample t test, pre‐ and 24‐month post‐operative Banff Patellofemoral Instability Instrument (BPII) scores were assessed for differences in clinical outcomes between patients with and without patella alta. Pearson (for continuous variables) and Spearman rank correlations (for binary/ordinal variables) were calculated to determine the relationship between the patellar height ratio, demographic and pathoanatomic risk factors, and pre‐ and post‐operative BPII scores. ResultsPre‐ and post‐operative true‐lateral radiographs were admissible for 229/283 patients (81%) following isolated MPFL reconstruction. A statistically significant difference in the Caton‐Deschamps index was evident from pre‐ to post‐operative for the entire cohort (p < 0.001). The mean decrease in ratio was 0.03, and the effect size was 0.27, classified as small. Pre‐operatively 52/229 patients (22.7%) demonstrated a Caton‐Deschamps index ≥ 1.2, mean = 1.27 (SD = 0.08); post‐operatively 21/229 patients (9.2%) demonstrated patella alta, mean = 1.18, (SD = 0.10), p < 0.001 (two‐tailed). The mean decrease in the Caton‐Deschamps index for patients with pre‐operative patella alta was 0.10; the effect size was 0.82, classified as large. Pearson r correlation of patella alta to the pre‐ and post‐operative BPII scores demonstrated no statistically significant relationship. ConclusionThis study has demonstrated that treatment of lateral patellofemoral instability with an isolated MPFL reconstruction results in a statistically significant decrease in patellar height ratio, with the effect size being greatest in patients with higher pre‐operative Caton‐Deschamps indices. In patients that presented with patella alta, normalization of the patellar height ratio occurred in 31/52 (59.6%) of the cases. Pre‐operative patella alta was not associated with a statistically significant difference in disease‐specific BPII outcome scores at any time point. Given these findings, the utility and results of tibial tubercle distalization in patients with patella alta should be a focus of further research.Level of evidenceIV.

The maintenance of a plasmid in the absence of selection for plasmid-borne genes is not guaranteed. However, plasmid persistence can evolve under selective conditions. Studying the molecular mechanisms behind the evolution of plasmid persistence is key to understanding how plasmids are maintained under nonselective conditions. Given the current crisis of rapid antibiotic resistance spread by multidrug resistance plasmids, this insight is of high medical relevance. The conventional method for monitoring plasmid persistence (i.e., the fraction of plasmid-containing cells in a population over time) is based on cultivation and involves differentiating colonies of plasmid-containing and plasmid-free cells on agar plates. However, this technique is timeconsuming and does not easily lend itself to high-throughput applications. Here, we present flow cytometry (FCM) and real-time quantitative PCR (qPCR) as alternative tools for monitoring plasmid persistence. For this, we measured the persistence of a model plasmid, pB10::gfp, in three Pseudomonas hosts and in known mixtures of plasmid-containing and -free cells. We also compared three performance criteria: dynamic range, resolution, and variance. Although not without exceptions, both techniques generated estimates of overall plasmid loss rates that were rather similar to those generated by the conventional plate count (PC) method. They also were able to resolve differences in loss rates between artificial plasmid persistence assays. Finally, we briefly discuss the advantages and disadvantages for each technique and conclude that, overall, both FCM and real-time qPCR are suitable alternatives to cultivation-based methods for routine measurement of plasmid persistence, thereby opening avenues for high-throughput analyses.

Background:Idiopathic adhesive capsulitis is a condition of uncertain etiology characterized by pain and decreased shoulder range of motion (ROM) that occurs without a known intrinsic disorder. Many treatments have been advocated, yet the best option remains unclear. The purpose of this study was to determine if arthrographic injection of the shoulder joint with steroid and local anesthetic results in decreased pain and increased shoulder function in a cohort of patients with idiopathic adhesive capsulitis.Methods:This is a retrospective case series of patients who were treated with an arthrographic steroid and local anesthetic injection for adhesive capsulitis. The injections were all given by the same musculoskeletal radiologist using image guidance, and the patients were all from the same surgeon's practice. Patients were evaluated with the Shoulder Pain and Disability Questionnaire (SPADI) and Constant Shoulder Score and their shoulder ROM was tested. Descriptive statistics in the form of counts, percentages, means and standard deviations were used, as well as parametric and non-parametric tests.Results:Thirty-three shoulders in 25 patients were examined. The average length of follow-up was 17 months. Sixty-nine percent of the cohort continued to complain of some shoulder pain in the post-injection follow-up clinic, however, their pain had improved from 8.8/10 pre-injection to 2.2/10 post-injection (p=0.01). The average score of the SPADI Pain, SPADI Disability and Constant Score were 36, 31 and 64, respectively.Conclusion:All patients who received an arthrographic injection using steroid and local anesthetic reported improved pain and mobility. In addition, those who had tried other treatment modalities felt that the injection had been the most beneficial.

Background: Exercise is widely regarded to improve pain and function in patients with knee osteoarthritis (OA) through building supportive muscle mass, facilitating weight loss, and through the other beneficial effects associated with it. Purpose: To explore literature that presents clinical guidelines for the use of exercise in the treatment of knee OA to inform an evidence-based position statement for the Arthroscopy Association of Canada. Study Design: Position statement. Methods: PubMed, MEDLINE, Embase, and Cochrane databases were searched for guidelines commenting on the role of exercise for knee OA. The search was limited to guidelines published in the last 10 years. Articles were screened for relevance, focusing on recently published research with clinical guidelines. Inclusion criteria involved all articles providing clinical guidelines for exercise and knee OA. Results: Eight guidelines were identified. All eight recommended exercise as an important component of treatment for knee OA, with 6/8 strongly recommending it. Conclusion: Exercise is an effective and important component of the non-pharmacological management of knee OA. The Arthroscopy Association of Canada strongly recommends the use of exercise in the management of knee OA.

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