A sliding stem in revision total knee arthroplasty provides stability and reduces stress shielding: An RSA study using impaction bone grafting in synthetic femora

Background and purpose

In the reconstruction of unicondylar femoral bone defects with morselized bone grafts in revision total knee arthroplasty, a stem extension appears to be critical to obtain adequate mechanical stability. Whether stability is still assured by this reconstruction technique in bicondylar defects has not been assessed. The disadvantage of relatively stiff stem extensions is that bone resorption is promoted due to stress shielding. We therefore designed a stem that would permit axial sliding movements of the articulating part relative to the intramedullary stem.

Methods

This stem was used in the reconstruction with impaction bone grafting (IBG) of 5 synthetic distal femora with a bicondylar defect. A cyclically axial load was applied to the prosthetic condyles to assess the stability of the reconstruction. Radiostereometry was used to determine the migrations of the femoral component with a rigidly connected stem, a sliding stem, and no stem extension.

Results

We found a stable reconstruction of the bicondylar femoral defects with IBG in the case of a rigidly connected stem. After disconnecting the stem, the femoral component showed substantially more migrations. With a sliding stem, rotational migrations were similar to those of a rigidly connected stem. However, the sliding stem allowed proximal migration of the condylar component, thereby compressing the IBG.

Interpretation

The presence of a functional stem extension is important for the stability of a bicondylar reconstruction. A sliding stem provides adequate stability, while stress shielding is reduced because compressive contact forces are still transmitted to the distal femoral bone.     

Developing Entrustable Professional Activities as the Basis for Assessment of Competence in an Internal Medicine Residency: A Feasibility Study

BACKGROUND

Graduate medical education programs assess trainees’ performance to determine readiness for unsupervised practice. Entrustable professional activities (EPAs) are a novel approach for assessing performance of core professional tasks.

AIM

To describe a pilot and feasibility evaluation of two EPAs for competency-based assessment in internal medicine (IM) residency.

SETTING/PARTICIPANTS

Post-graduate year-1 interns (PGY-1s) and attendings at a large internal medicine (IM) residency program.

PROGRAM DESCRIPTION

Two Entrustable professional activities (EPA) assessments (Discharge, Family Meeting) were piloted.

PROGRAM FEASIBILITY EVALUATION

Twenty-eight out of 43 (65.1 %) PGY-1 s and 32/43 (74.4 %) attendings completed surveys about the Discharge EPA experience. Most who completed the EPA assessment (10/12, 83.8 %, PGY-1s; 9/11, 83.3 %, attendings) agreed it facilitated useful feedback discussions. For the Family Meeting EPA, 16/26 (61.5 %) PGY-1s completed surveys, and most who participated (9/12 PGY1s, 75 %) reported it improved attention to family meeting education, although only half recommended continuing the EPA assessment.

DISCUSSION

From piloting two EPA assessments in a large IM residency, we recognized our reminder systems and time dedicated for completing EPA requirements as inadequate. Collaboration around patient safety and palliative care with relevant clinical services has enhanced implementation and buy-in. We will evaluate how well EPA-based assessment serves the intended purpose of capturing trainees’ trustworthiness to conduct activities unsupervised.     

Prediction of virologic response in difficult-to-treat chronic hepatitis C patients during high-dose interferon induction therapy

Objective. To determine (i) whether early viral kinetics or other markers during a modified treatment regimen are predictors of treatment outcome and (ii) whether fast responders can be treated for 24 weeks, without compromising the sustained virologic response (SVR) rate. Material and methods. One hundred “difficult-to-treat” chronic hepatitis C patients (46 previous non-responders/relapsers (any genotype), 54 treatment-naive patients genotypes 1 and 4) were treated with triple antiviral induction therapy: amantadine hydrochloride and ribavirin, combined with 6 weeks interferon alfa-2b induction (weeks 1–2: 18 MU/day, weeks 3–4: 9 MU/day, weeks 5–6: 6 MU/day), thereafter combined with weekly peginterferon alfa-2b. Fast responders (≥3 log₁₀ HCV RNA decline at week 4) were randomized to 24 or 48 weeks. Slow responders (<3 log₁₀ HCV RNA decline at week 4) were treated for 48 weeks. Treatment was stopped in patients with detectable HCV RNA at week 24. Results. Thirty-six patients achieved SVR: 28 of 60 fast responders (47%) versus 8 of 32 slow responders (25%, p<0.05). Relapse rates among fast responders treated for 24 or 48 weeks were 27% and 20%, respectively (p=NS). SVR in fast responders was independent of baseline HCV RNA ≥ or <600,000 IU/mL. All treatment-naive patients with HCV RNA <5 IU/mL at week 1 or 2 achieved SVR; all treatment-naive patients with HCV RNA ≥5 IU/mL at week 16 became non-SVR. In previous non-responders/relapsers, the predictive value for SVR was 83% if HCV RNA was <5 IU/mL at week 2; all previous non-responders/relapsers with HCV RNA ≥5 IU/mL at week 8 became non-SVR. Conclusions. With high-dose interferon induction, SVR and non-SVR can be predicted reliably within 16 weeks. Fast responders can be treated for 24 weeks, and SVR is independent of baseline viral load in fast responders.     

Bone Mineral Density is Not Correlated with One-Year Functional Outcome in Distal Radial Fractures: A Preliminary Study

Abstract Introduction:   The intrinsic stability of fractures related to soft tissue injury and the comminution of the metaphyseal part of the distal radius influence the chance of secondary displacement in distal radial fractures treated conservatively. A low bone mineral density may also contribute to this secondary displacement and could therefore play a role in functional outcome. This possible relation between functional outcome and bone mineral density is poorly studied. Patients and Methods:   Patients with a unilateral conservatively treated distal radial fracture were assessed one year after their fracture with the DASH score (disabilities of the arm, shoulder and hand) and the Cooney score. Fractures were classified according to the AO classification. Radial inclination, radial shift, radial tilt and ulnar variance were measured on the first and follow-up radiographies. Bone mineral densities of both the hip and lumbar spine were measured by DXA and expressed as T-scores. Results:   Fifty-four patients participated in this study (mean age 68 years). Osteoporosis (T-score ≤ –2.5) was present in 20 patients (37%), osteopenia (T-score of –1 to –2.5) in 30 patients (56%), and normal bone density (T-score > –1) in four patients (7%). The distribution of fracture types according to the AO classification showed 32 A-type fractures, eight B-type fractures and 14 C-type fractures. Both univariate linear and multivariate regression analysis with covariates of age, sex, body mass index and AO classification showed no significant correlation between T-score and functional outcome. Conclusion:   The functional outcome of conservatively treated distal radial fractures in this study does not correlate with bone mineral density. Therefore, BMD measurement cannot be used to predict functional outcome in these patients.     

Is surveillance of the small bowel indicated for Lynch syndrome families?

BACKGROUND: Small bowel cancer (SBC) is one of the tumours associated with Lynch syndrome (LS). To advise on screening for this tumour it is paramount to be informed about the lifetime risk. The aim of this study was to calculate the lifetime risk of SBC in LS and to identify possible risk factors. METHODS: Clinical and pathological data were collected on 1496 proven or putative carriers of a mismatch repair gene mutation from 189 families. Kaplan-Meier survival analysis was used to calculate the lifetime risk and to assess potential risk factors. RESULTS: 28 (1.9%) of the 1496 (putative) mutation carriers were identified with SBC. The median age at diagnosis was 52 years (range 23-69 years). The lifetime risk of developing SBC was 4.2%. There was no difference in risk between males and females (log rank: p = 0.2470), or between MLH1 and MSH2 mutation carriers (log rank: p = 0.2754). SBC was not observed in MSH6 mutation carriers (n = 203). The previous occurrence of colorectal cancer and a family history of SBC did not increase the risk significantly. CONCLUSIONS: Approximately, one out of 25 mutation carriers will develop SBC during life. No specific risk factors were identified. The risk appeared to be too low to advise screening by means of an invasive burdensome procedure like double balloon enteroscopy. However, screening by a non-invasive procedure (videocapsule endoscopy) might be considered if future studies will show its cost effectiveness. In patients with unexplained abdominal complaints and/or unexplained iron deficiency anaemia SBC should be considered.     

Keeping up with the next generation: massively parallel sequencing in clinical diagnostics

The speed, accuracy, efficiency, and cost-effectiveness of DNA sequencing have been improving continuously since the initial derivation of the technique in the mid-1970s. With the advent of massively parallel sequencing technologies, DNA sequencing costs have been dramatically reduced. No longer is it unthinkable to sequence hundreds or even thousands of genes in a single individual with a suspected genetic disease or complex disease predisposition. Along with the benefits offered by these technologies come a number of challenges that must be addressed before wide-scale sequencing becomes accepted medical practice. Molecular diagnosticians will need to become comfortable with, and gain confidence in, these new platforms, which are based on radically different technologies compared to the standard DNA sequencers in routine use today. Experience will determine whether these instruments are best applied to sequencing versus resequencing. Perhaps most importantly, along with increasing read lengths inevitably comes increased ascertainment of novel sequence variants of uncertain clinical significance, the postanalytical aspects of which could bog down the entire field. But despite these obstacles, and as a direct result of the promises these sequencing advances present, it will likely not be long before next-generation sequencing begins to make an impact in molecular medicine. In this review, technical issues are discussed, in addition to the practical considerations that will need to be addressed as advances push toward personal genome sequencing.     

An integrated approach to determine left atrial volume, mass and function in hypertrophic cardiomyopathy by two-dimensional echocardiography

Methods

The study included 25 hypertrophic cardiomyopathy (HCM) patients (15 non-obstructive and 10 obstructive) and 25 controls for assessment of left atrial (LA) volume, mass and function by two-dimensional echocardiography. Measurement included mean LA diameter (LAD), LA mass = {(mean LAD + anterior LA wall + posterior LA wall)³ ? mean LAD³} × 0.8 + 0.6, LA volume = [(8/3 π L · A1 · A2), where L is LA length, A1 and A2 are LA area in 4-chambers and 2-chambers, respectively] including maximum (V _max), minimum (V _min), and pre-atrial contraction (V _pre-A), total atrial stroke volume (TA-SV), TA emptying fraction (TA-EF), active atrial SV (AA-SV), AA-EF, passive atrial SV (PA-SV), PA-EF, atrial expansion index (AEI), and LA kinetic energy (LA-KE) = ½ × AA-SV × P × V².

Results

LAD, LA mass, V _max, V _min, and V _pre-A were significantly higher in HCM than controls. TA-SV and TA-EF were comparable in both HCM subgroups and controls. AA-SV and LA-KE were significantly higher in both HCM subgroups than controls. LA-KE was significantly higher in obstructive HCM than non-obstructive (P < 0.001). PA-EF and AEI were significantly lower in obstructive HCM than controls (P < 0.05).

Conclusion

HCM is associated with increased LA size and augmented LA pump function especially obstructive type. LA conduit and reservoir functions are impaired in obstructive HCM.     

Long-term outcome of juvenile idiopathic arthritis following a placebo-controlled trial: sustained benefits of early sulfasalazine treatment

OBJECTIVES: A previous 24-week randomised trial demonstrated that sulfasalazine (SSZ) treatment was superior to placebo (PLAC) in suppressing disease activity in patients with oligo- and polyarticular onset juvenile idiopathic arthritis (JIA). The current study determines the long-term outcome of the trial participants and evaluates whether the benefits of SSZ allocation are sustained over time. METHODS: Between 2001 and 2003, 32 SSZ and 29 PLAC patients (90% of all patients) were prospectively examined clinically and by chart review, median 9 years (range 7 to 10) after trial inclusion. In the follow-up assessment, variables of the American College of Rheumatology Pediatric 30 (ACR Pedi 30) criteria were collected. The assessor was blinded to trial treatment allocation. RESULTS: After the trial, patients had been routinely followed in rheumatology referral centres, and treated at the discretion of the attending physician. Almost all patients continued or started disease-modifying antirheumatic drugs (DMARDs) (SSZ 91%, PLAC 93%; SSZ treatment in about 80%). DMARD treatment appeared less intensive in the SSZ group as evidenced by a significantly shorter duration of SSZ use (median 2.5 vs 5.2 years; p = 0.02) and a trend towards less use of methotrexate and other DMARDs. More than one-third of the patients reported long periods of non-compliance with DMARD treatment in both groups. At follow-up, 74% of the patients had active joints, and 30% showed active polyarthritis. Almost all outcome scores were better for SSZ compared with PLAC patients. Differences (often exceeding 50%) were significant for the number of active joints, patients' overall well-being, number of patients with episodes of clinical remission off medication (CROM) and duration of these episodes, patients in CROM and ACR Pedi 30 response at follow-up. Additional exploratory analyses performed to detect potential confounders related to patient characteristics or follow-up treatment showed that DMARD treatment compliance was positively correlated with an ACR Pedi 30 response (odds ratio 3.8, 95% confidence interval (CI) 1.1 to 13.4; p = 0.03). Adjusted for compliance, an SSZ patient was 4.2 times as likely as a PLAC patient to be an ACR Pedi 30 responder at follow-up (95% CI 1.3 to 14.3; p = 0.02). CONCLUSIONS: This follow-up study shows that effective suppression of disease activity by SSZ treatment early in active disease in JIA patients has beneficial effects that persist for many years. Given these results, compliance with DMARD treatment deserves serious attention.