Mechanical comparison of biodegradable femoral fixation devices for hamstring tendon graft – A biomechanical study in a porcine model

Background

Initial fixation strength is critical for the early post-operative rehabilitation of patients with anterior cruciate ligament reconstructions. However, even the best femoral fixation devices remain controversial. We compared the biomechanical characteristics of tendon grafts fixed by different biodegradable femoral fixation devices following anterior cruciate ligament reconstruction.

Methods

The Bio-TransFix, Rigidfix, Bioscrew with EndoPearl augmentation and Bioscrew devices were used to fix porcine flexor digitorum profundus tendon grafts in 32 porcine femora. Displacement of each tendon graft was evaluated after cyclic loading testing. Stiffness, ultimate failure load and failure mode of these fixation devices were measured with load-to-failure testing.

Findings

The displacement of the femur–graft–cement complex in response to cyclic loading was lower (P < 0.05) for the Bio-TransFix than the Rigidfix, Bioscrew with EndoPearl augmentation, and Bioscrew groups. The fixation stiffness values of the Rigidfix and the Bioscrew were significantly greater (P < 0.05) than that of the Bio-TransFix. The ultimate failure load was significantly greater for the Bio-TransFix and the Rigidfix than the Bioscrew with EndoPearl augmentation or the Bioscrew (P < 0.05).

Interpretation

The Bio-TransFix provided the least graft displacement under cyclic loading. However, this device gave less stability. The Rigidfix device provided better stability and stiffness of the tendon graft among those fixation devices that showed no significant differences in graft displacement under cyclic loading. However, no single fixation device provided less displacement along with a larger failure load and stiffness in this study.     

A novel internal fixation method for open book injuries of the pubic symphysis— A biomechanical analysis

BackgroundPelvic fractures in adults are common injuries and account for up to 3.64% of all fractures. Usually, the treatment of open book injuries (Types B1.1 and B1.2 AO-Classification) is open reduction and plate stabilization using dynamic compression plates, with or without interlocking screws. These implants seem to enhance the outcome of such injuries, but also variety of complications occurs. To reduce complications and achieve appropriate reduction and stabilization, this study compared established stabilization techniques to a novel minimally invasive internal fixation method using an internal fixator system that is already being utilized for spinal fractures.MethodsThis study was performed on 32 composite pelvises in a bilateral stance biomechanical model. The pelvises were variously stabilized with an internal fixator, a 4.5 mm dynamic compression plate and a 3.5 mm symphyseal locking dynamic compression plate. The contact area and loading forces were assessed by a sensor film inside the symphyseal gap.FindingsThis study showed significantly greater reduction and loading capabilities of the internal fixator compared to the other implants (p < 0.05). There was also significantly greater contact area with the use of an internal fixator compared to the other implants (p < 0.05). The 3.5 mm interlocking plate showed significantly greater contact area compared to the 4.5 mm plate (p < 0.05).InterpretationThe internal fixator that is already proven in spinal surgery is biomechanically superior to conventional implants used in pelvic surgery. The contact area analysis furthermore showed a more physiological loading pattern, which can improve ligamentous healing in a clinical context.     

Increased consultation frequency in primary care,a risk marker for cancer: a case–control study

Objective: To identify early diagnostic profiles such as diagnostic codes and consultation patterns of cancer patients in primary care one year prior to cancer diagnosis.

Design: Total population-based case–control study.

Setting and subjects: 4562 cancer patients and 17,979 controls matched by age, sex, and primary care unit. Data were collected from the Swedish Cancer Register and the Regional Healthcare Database.

Method: We identified cancer patients in the Västra Götaland Region of Sweden diagnosed in 2011 with prostate, breast, colorectal, lung, gynaecological, and skin cancers including malignant melanoma. We studied the symptoms and diagnoses identified by diagnostic codes during a diagnostic interval of 12 months before the cancer diagnosis.

Main outcome measures: Consultation frequency, symptom density by cancer type, prevalence and odds ratios (OR) for the diagnostic codes in the cancer population as a whole.

Results: The diagnostic codes with the highest OR were unspecified lump in breast, neoplasm of uncertain behaviour, and abnormal serum enzyme levels. The codes with the highest prevalence were hyperplasia of prostate, other skin changes and abdominal and pelvic pain. The frequency of diagnostic codes and consultations in primary care rose in tandem 50 days before diagnosis for breast and gynaecological cancer, 60 days for malignant melanoma and skin cancer, 80 days for prostate cancer and 100 days for colorectal and lung cancer.

Conclusion: Eighty-seven percent of patients with the most common cancers consulted a general practitioner (GP) a year before their diagnosis. An increase in consultation frequency and presentation of any symptom should raise the GP’s suspicion of cancer.

Key Points

Knowledge about the prevalence of early symptoms and other clinical signs in cancer patients in primary care remains insufficient.

• Eighty-seven percent of the patients with the seven most common cancers consulted a general practitioner 12 months prior to cancer diagnosis.

• Both the frequency of consultation and the number of symptoms and diseases expressed in diagnostic codes rose in tandem 50–100 days before the cancer diagnosis.

• Unless it is caused by a previously known disease, an increased consultation rate for any symptom should result in a swift investigation or referral from primary care to confirm or exclude cancer.

     

Drugs for men and women - how important is gender as a risk factor for TdP?

The cardiac arrhythmia known as torsade de pointes (TdP), which is a very rare but potentially lethal side effect of a variety of drugs, occurs approximately twice as often in women as it does in men. Most drugs that have this adverse effect prolong the repolarization phase of the cardiac action potential which can be detected by a lengthening of the QT interval on the ECG. The gender difference in susceptibility to TdP only appears after puberty suggesting that sex hormones are contributory factors. Studies in patients indicate that testosterone-induced shortening of action potential duration may account for the shorter rate-corrected QT interval in men rather than any effect of estradiol in women, whereas drug-induced QT prolongation can be potentiated by estradiol. Experimental investigations suggest that sex hormones may alter either Ca(2+) currents, K(+) currents, or both and that actions on these ionic currents may account for the gender differences in cardiac repolarization. Although estradiol exacerbated drug-induced TdP in an in vivo model, no similar information is available for progesterone or testosterone. Further studies are required to clarify the influence of these sex hormones and to investigate the importance of the balance between sex hormones in both genders. Such information would assist in risk:benefit analysis and may allow the development of "drugs for men" and "drugs for women".     

Increased risk for major depressive disorder in severely obese patients after bariatric surgery — a 12-year nationwide cohort study

Abstract

Background: Bariatric surgery is associated with a significant improvement in depressive mood in the initial postoperative years, but the maintenance of the improvement is under debate.

Aim: To explore the association between bariatric surgery and major depressive disorder (MDD) in a 12-year nationwide cohort study.

Method: Using the National Health Insurance Research Database of Taiwan, we identified 2302 patients who underwent bariatric surgery in 2001–2009. These patients were matched by propensity score to 6493 obese patients who did not receive bariatric surgery. We followed the surgical and control cohorts until death, any diagnosis of MDD or 31 December 2012. We used Cox proportional hazard regression models to calculate the relative risk of MDD in those who received bariatric surgery.

Results: Overall, there was a 1.70-fold (95% CI: 1.27–2.27) higher risk of MDD in the surgical group. Subjects receiving malabsorptive procedures showed a higher risk of MDD (3.01, 95% CI: 1.78–5.09) than those receiving restrictive procedures (1.51, 95% CI: 1.10–2.07). Stratified by follow-up period, there was a higher risk of MDD in the surgical group (2.92, 95% CI: 1.75–4.88) than in the restrictive group four years after bariatric surgery.

Conclusions: Bariatric surgery was significantly associated with an elevated risk of MDD.

• KEY MESSAGES

• Bariatric surgery is associated with a significant improvement in depressive mood in the initial postoperative years, but the improvement is not maintained. Less is known about the relationship between bariatric surgery and risk of major depressive disorder.

• This was the first nationwide cohort study which found that bariatric surgery was significantly associated with an elevated risk of MDD (aHR: 1.70; CI: 1.27–2.27), mainly with malabsorptive procedures (aHR: 3.01; CI: 1.78–5.09) and at time points more than four years after surgery (aHR: 2.92; CI: 1.75–4.88) compared with the risk in matched controls. These findings imply an association between long-term malabsorption and the postoperative incidence of MDD.

• Long-term malabsorption might be related to the incidence of major depressive disorder after bariatric surgery. The possible causal relationship between nutritional deficiency after bariatric surgery and major depressive disorder warrants further investigation.

     

Is a helical shaped implant a superior alternative to the Dynamic Hip Screw for unstable femoral neck fractures? A biomechanical investigation

Background

The Dynamic Hip Screw is well established for the treatment of femoral neck fractures. However, cut-out occurs in 1–6% of all cases. This study compared the biomechanical performance of a helical shaped implant (DHS-Blade) to the Dynamic Hip Screw in an unstable femoral neck fracture model.

Methods

Ten pairs of human cadaveric femora were either instrumented with a DHS-Blade or a Dynamic Hip Screw. Osteotomies were created using a custom-made saw-guide. Cyclic loading was performed by introducing in vivo measured load-trajectories to the femoral head. Starting at 1500 N, the load was stepwise increased until failure of the construct. Radiographs were taken in 5000 cycles increments to identify onset of femoral head migration with respect to the implant. A survival analysis was performed on the cycles to onset of migration. A paired t-test was carried out on the displacements of the femoral head relative to the shaft as determined by optical motion tracking.

Findings

One hundred percent migrations occurred for the Dynamic Hip Screw compared to 50% for the DHS-Blade. The survival probability in terms of implant anchorage was found higher for the blade (P = 0.023). However, significant higher deformation of the repair construct was observed for the DHS-Blade (P = 0.004).

Interpretation

The study showed superior implant anchorage of the DHS-Blade compared to the DHS, which might reduce the cut-out risk. Nevertheless, the blade allowed higher deformation of the femur mainly resulting in shortening of the neck, which might be due to a systematic loss of fracture reduction.     

Can a modified interspinous spacer prevent instability in axial rotation and lateral bending? A biomechanical in vitro study resulting in a new idea

BACKGROUND: Interspinous spacers are mainly used to treat lumbar spinal stenosis and facet arthrosis. Biomechanically, they stabilise in extension but do not compensate instability in axial rotation and lateral bending. It would therefore be desirable to have an interspinous spacer available, which provides for more stability also in these two planes. At the same time, the intervertebral disc should not completely be unloaded to keep it viable. To meet these requirements, a new version of the Coflex interspinous implant was developed, called "Coflex rivet", which can be more rigidly attached to the spinous processes. The aim was to investigate whether this new implant compensates instability but still allows some load to be transferred through the disc. METHODS: Twelve human lumbar spine segments were equally divided into two groups, one for Coflex rivet and one for the original Coflex implant. The specimens were tested for flexibility under pure moment loads in the three main planes. These tests were carried out in the intact condition, after creation of a destabilising defect and after insertion of either of the two implants. Before implantation, the interspinous spacers were equipped with strain gauges to measure the load transfer. FINDINGS: Compared to the defect condition, both implants had a strong stabilising effect in extension (P<0.05). Coflex rivet also strongly stabilised in flexion and to a smaller degree in lateral bending and axial rotation (P<0.05). In contrast, in these three loading directions, the original Coflex implant could not compensate the destabilising effect of the defect (P>0.05). The bending moments transferred through the implants were highest in extension and flexion. Yet, they were no more than 1.2 Nm in median. INTERPRETATION: The new Coflex rivet seems be a suitable option to compensate instability. Its biomechanical characteristics might even make it suitable as an adjunct to fusion, which would be a new indication for this type of implant.     

Preoperative pain as a risk factor for chronic post-surgical pain – Six month follow-up after radical prostatectomy

BackgroundChronic post-surgical pain (CPSP) by definition develops for the first time after surgery and is not related to any preoperative pain. Preoperative pain is assumed to be a major risk factor for CPSP. Prospective studies to endorse this assumption are missing.MethodsIn order to assess the incidence and the risk factors for CPSP multidimensional pain and health characteristics and psychological aspects were studied in patients prior to radical prostatectomy. Follow-up questionnaires were completed three and six months after surgery.ResultsCPSP incidences in 84 patients after three and six months were 14.3% and 1.2%. Preoperatively, CPSP patients were assigned to higher pain chronicity stages measured with the Mainz Pain Staging System (MPSS) (p = 0.003) and higher pain severity grades (Chronic Pain Grading Questionnaire) (p = 0.016) than non-CPSP patients. CPSP patients reported more pain sites (p = 0.001), frequent pain in urological body areas (p = 0.047), previous occurrence of CPSP (p = 0.008), more psychosomatic symptoms (Symptom Check List) (p = 0.031), and worse mental functioning (Short Form-12) (p = 0.019). Three months after surgery all CPSP patients suffered from moderate to high-risk chronic pain (MPSS stages II and III) compared to 66.7% at baseline and 82.3% had high disability pain (CPGQ grades III and IV) compared to 41.7% before surgery. CPSP patients scored significantly less favorably in physical and mental health, habitual well-being, and psychosomatic dysfunction three months after surgery.ConclusionsAll patients with CPSP reported on preoperative chronic pain. Patients with preoperative pain, related or not related to the surgical site were significantly at risk to develop CPSP. High preoperative pain chronicity stages and pain severity grades were associated with CPSP. CPSP patients reported poorer mental health related quality of life and more severe psychosomatic dysfunction before and 3 months after surgery.     

Clinical outcomes for babies born between 27 – 31 weeks of gestation: Should they be regarded as a single cohort?

Preterm babies born between 27 and 31 weeks of gestation are understudied and historically, have been grouped as a single cohort. Increased evidence relating to clinical outcomes is shaping models of care for babies born ≤26 weeks of gestation. Similar consideration of births between 27 and 31 weeks of gestation is now warranted. To address this, a clear understanding of the impact of progressive maturation in utero on the clinical care required, and on neonatal and infant outcomes of this group of preterm babies is helpful.In this review we highlight the spectrum of clinical presentations for babies born at 27–31 weeks of gestation. We discuss this with respect to key stages of organ/system development occurring in-utero during this five-week period and reveal a consistent trend of decreasing incidence of mortality and major morbidity with increasing gestational age at birth from 27 to 31 weeks. The clinical care required and the outcomes between babies born at either end of this gestational age range appear to be substantially different. This suggests it may be more appropriate to report outcomes by week of gestation rather than as a group in future research. Preterm health service delivery providers and decision makers need to consider this in planning services for the future, especially in environments where neonatal intensive care resources ought to be optimised for those at greatest need.     

Can the need for a physician as part of the pediatric transport team be predicted? A prospective study.

OBJECTIVES: To evaluate the quality of objective information obtained during telephone requests for the transport of pediatric patients. To evaluate the ability of subjective judgment, the Pediatric Risk of Mortality (PRISM) score, and the presence of tachycardia for age to predict the need for a physician on as a member of the pediatric transport team. DESIGN: Prospective data collection. SETTING: The pediatric transport program of a children's hospital. PATIENTS: All 129 infants and children transported over a 4-month period. MEASUREMENTS AND MAIN RESULTS: We defined an objective measure of the need for a physician's presence during the transport of a pediatric patient, based on either the necessity for procedural or medical interventions during the time of transport or on direct admission to the pediatric ICU after transport. At the time of initial telephone contact, a physician's subjective opinion of the need for physician presence was recorded, a PRISM score was derived, and the presence of tachycardia (adjusted for age) was determined. Subsequently, the vital signs recorded on the record of this request were compared with those vital signs charted at the referring hospital at the time of the initial telephone request. A total of 96% of vital signs obtained during the initial telephone contact were consistent with those percentages in the referring hospital medical records. Fifty (39%) of 129 transported patients required procedural or medical interventions or pediatric ICU admission. Subjective judgments predicted physician need with a high sensitivity (0.98), but with a low specificity (0.18). PRISM score predicted 62 (48%) of 129 transports to be "physician-required" (sensitivity = 0.72; specificity = 0.67). There was no statistical association between tachycardia for age and the objective need for a physician's presence. CONCLUSIONS: Objective information obtained during request for transfer was reliable. At the time of request for transfer, subjective judgment, PRISM score, and the presence of tachycardia did not predict the need for a physician presence during transport.     

Mallet finger – A modified technique using the finger nail as a fixation point for the temporary immobilization of the distal interphalangeal joint – A biomechanical study

BackgroundThe aim of the current biomechanical study was to investigate a newly developed surgical technique for mallet fingers. The new method is based on the Ishiguro method which requires a K-wire through the distal interphalangeal joint for temporary fixation. The new technique avoids the joint trans fixation using a specially designed finger nail holder. This method was compared to the established Ishiguro's technique.MethodsFor biomechanical testing, 32 paired, fresh-frozen human fingers (Digit II–V) of 4 donors (ages 60 to 71 years) were used. The paired fingers were assigned to either the new method or Ishiguro's technique. The biomechanical testing consisted of a cyclic cantilever bending (2000 cycles, 1–7N) followed by a load to failure test. The groups were evaluated for plastic deformation, stiffness, change in stiffness during cyclic loading, subluxation and failure load by analysing force-deflect data and fluoroscopic images.FindingsThe nail fixation group showed significantly higher failure loads and stiffness than the trans fixation group. The values of plastic deformation were significantly lower in the nail fixation group. No differences were found in the change of stiffness. No subluxation was found in both groups.InterpretationIn the current biomechanical study, nail fixation performed at least as good as Ishiguro's trans fixation technique. The results and ease of implementation indicate that the newly developed nail fixation technique might be a useful treatment method in daily clinical practice without the need of temporary joint trans-fixation avoiding possible associated problems. To establish this method, clinical trials will be necessary.     

Care managers can be useful for patients with depression but their role must be clear: a qualitative study of GPs’ experiences

Abstract

Objective: Explore general practitioners’ (GPs’) views on and experiences of working with care managers for patients treated for depression in primary care settings. Care managers are specially trained health care professionals, often specialist nurses, who coordinate care for patients with chronic diseases.

Design: Qualitative content analysis of five focus-group discussions.

Setting: Primary health care centers in the Region of Västra Götaland and Dalarna County, Sweden.

Subjects: 29 GPs.

Main outcome measures: GPs’ views and experiences of care managers for patients with depression.

Results: GPs expressed a broad variety of views and experiences. Care managers could ensure care quality while freeing GPs from case management by providing support for patients and security and relief for GPs and by coordinating patient care. GPs could also express concern about role overlap; specifically, that GPs are already care managers, that too many caregivers disrupt patient contact, and that the roles of care managers and psychotherapists seem to compete. GPs thought care managers should be assigned to patients who need them the most (e.g. patients with life difficulties or severe mental health problems). They also found that transition to a chronic care model required change, including alterations in the way GPs worked and changes that made depression treatment more like treatment for other chronic diseases.

Conclusion: GPs have varied experiences of care managers. As a complementary part of the primary health care team, care managers can be useful for patients with depression, but team members’ roles must be clear.

• KEY POINTS

• A growing number of primary health care centers are introducing care managers for patients with depression, but knowledge about GPs’ experiences of this kind of collaborative care is limited.

• GPs find that care managers provide support for patients and security and relief for GPs.

• GPs are concerned about potential role overlap and desire greater latitude in deciding which patients can be assigned a care manager.

• GPs think depression can be treated using a chronic care model that includes care managers but that adjusting to the new way of working will take time.

     

The desire to be fashionable. Should we consider it a risk factor for infection in adolescents with acute leukaemia?

Three cases of skin infection, two with Pseudomonas aeruginosa and one with Staphylococcus aureus in three adolescents with acute leukaemia are described. In all cases the infection was clearly related to the latest fashion in shoes. This report underline the fact that factors related to everyday life and less frequently considered than those related to the underlying illness can also put increase the risk of developing severe infections in immunocompromised patients.