Aseptic midterm survival rates between different cemented tibial stem designs in hinged total knee arthroplasty: a 6-year evaluation from the German Arthroplasty Registry.

INTRODUCTION: The rate of revision TKA and thus the use of hinged implants (HI) steadily rises. Aseptic loosening lies on the top of the failure patterns. However, no evidence exists until now based on national scale high-caseloads that analyzes the impact of cemented HI stem-design on aseptic survival rates. METHODS: Data on aseptic HI-revisions with full-cemented tibia-stems were conducted from the German Arthroplasty Registry. Cases were divided in primary HI (PHI) and HI used in revision operations (RHI). Endpoint was a new revision following either a PHI or an RHI. The impact of stem conicity (conical vs. cylindrical), diameter (≤ 13 mm vs. > 13 mm), length (≤ 90 mm vs. > 90 mm) and offset on the 6-Year-Cumulative-Aseptic-Revision-Rate (6Y-CARR) was estimated via Kaplan-Meier curve and compared between groups via Log-Rank-Tests. RESULTS: 3953 PHI and 2032 RHI fulfilled inclusion-criteria. Stem conicity had no impact on 6Y-CARR (p = 0.08 and p = 0.8). Diameter > 13 mm hat an impact on PHI (p = 0.05) with lower 6Y-CARR but not on RHI (p = 0.2). Length > 90 mm showed significantly worst 6Y-CARR in PHI (p = 0.0001) but not in RHI (p = 0.3). Offset-stems showed significantly better 6Y-CARR in PHI (p = 0.04), but not in RHI (p = 0.7). CONCLUSION: There was no significant impact of the cemented tibia-stem conicity on 6Y-CARR, neither in PHI nor in RHI. The effect of length, diameter and offset on the 6Y-CARR observed in the PHI, was not detectable in the more complex RHI-cases reflecting its limited clinical relevance by itself in more multifactorial backgrounds. Therefore, results must be interpreted with caution due to considerable system-effects and different utilization-scenarios.

Improving embryonic stem cell expansion through the combination of perfusion and Bioprocess model design.

BACKGROUND: High proliferative and differentiation capacity renders embryonic stem cells (ESCs) a promising cell source for tissue engineering and cell-based therapies. Harnessing their potential, however, requires well-designed, efficient and reproducible expansion and differentiation protocols as well as avoiding hazardous by-products, such as teratoma formation. Traditional, standard culture methodologies are fragmented and limited in their fed-batch feeding strategies that afford a sub-optimal environment for cellular metabolism. Herein, we investigate the impact of metabolic stress as a result of inefficient feeding utilizing a novel perfusion bioreactor and a mathematical model to achieve bioprocess improvement. METHODOLOGY/PRINCIPAL FINDINGS: To characterize nutritional requirements, the expansion of undifferentiated murine ESCs (mESCs) encapsulated in hydrogels was performed in batch and perfusion cultures using bioreactors. Despite sufficient nutrient and growth factor provision, the accumulation of inhibitory metabolites resulted in the unscheduled differentiation of mESCs and a decline in their cell numbers in the batch cultures. In contrast, perfusion cultures maintained metabolite concentration below toxic levels, resulting in the robust expansion (>16-fold) of high quality 'naïve' mESCs within 4 days. A multi-scale mathematical model describing population segregated growth kinetics, metabolism and the expression of selected pluripotency ('stemness') genes was implemented to maximize information from available experimental data. A global sensitivity analysis (GSA) was employed that identified significant (6/29) model parameters and enabled model validation. Predicting the preferential propagation of undifferentiated ESCs in perfusion culture conditions demonstrates synchrony between theory and experiment. CONCLUSIONS/SIGNIFICANCE: The limitations of batch culture highlight the importance of cellular metabolism in maintaining pluripotency, which necessitates the design of suitable ESC bioprocesses. We propose a novel investigational framework that integrates a novel perfusion culture platform (controlled metabolic conditions) with mathematical modeling (information maximization) to enhance ESC bioprocess productivity and facilitate bioprocess optimization.

Periprosthetic fractures in the distal femur following total knee replacement: A review and guide to management.

The management of distal femoral fractures following a total knee replacement can be complex and requires the equipment, perioperative support and surgical skills of both trauma and revision arthroplasty services. Recent advances in implant technology have changed the management options of these difficult fractures. This article describes the options available and discusses the latest evidence.

Does image guidance improve accuracy of core needle biopsy in diagnosis of soft tissue tumours?

The aim of this study was to compare accuracy of an image guided percutaneous core needle biopsy (PCNB), using ultrasound or computed tomography, to PCNB without image guidance in the diagnosis of palpable soft tissue tumours. One hundred forty patients with a suspected soft tissue sarcoma underwent a percutaneous core needle biopsy with or without image guidance. One hundred eleven patients had subsequent surgical excision. The accuracy of guided PCNB and blind PCNB was calculated by comparing the histological results of the needle biopsy to the surgical specimen. The diagnostic accuracy of blind percutaneous core needle biopsy was 78% (36 of 46 biopsies) and was significantly lower (p < or = 0.025) in comparison to image guided percutaneous core needle biopsy, which was 95% (62 of 65 biopsies). We suggest that image guidance improves the diagnostic accuracy of PCNB especially for small-size deep sited suspected soft tissue tumours.

Minimally invasive versus open transforaminal lumbar interbody fusion: evaluating initial experience.

The aim of this study was to compare our experience with minimally invasive transforaminal lumbar interbody fusion (MITLIF) and open midline transforaminal lumbar interbody fusion (TLIF). A total of 36 patients suffering from isthmic spondylolisthesis or degenerative disc disease were operated with either a MITLIF (n = 18) or an open TLIF technique (n = 18) with an average follow-up of 22 and 24 months, respectively. Clinical outcome was assessed using the visual analogue scale (VAS) and the Oswestry disability index (ODI). There was no difference in length of surgery between the two groups. The MITLIF group resulted in a significant reduction of blood loss and had a shorter length of hospital stay. No difference was observed in postoperative pain, initial analgesia consumption, VAS or ODI between the groups. Three pseudarthroses were observed in the MITLIF group although this was not statistically significant. A steeper learning effect was observed for the MITLIF group.

Microendoscopic discectomy compared with standard microsurgical discectomy for treatment of uncontained or large contained disc herniations.

OBJECTIVE: Minimally invasive spinal techniques have been developed for years in an attempt to minimize trauma. However, most endoscopic techniques have been unable to address uncontained or large contained disc herniations. The aim of this prospective study was to compare the results of microendoscopic discectomy (MED) and microsurgical discectomy in the treatment of patients with uncontained or large contained disc herniations. METHODS: An independent observer reviewed the treatment of 28 patients. The study group included 14 consecutive patients who underwent MED and 14 consecutive patients who underwent microsurgical discectomy for radicular pain secondary to uncontained or large contained disc herniations during the same period. Patients were followed up for an average of 12 months. They were assessed by use of Oswestry disability questionnaire and low back pain outcome score. RESULTS: The average outcome score improvement was of clinical significance in both patient groups. No difference in the scores was found between the two groups. Patients in the MED group required less postoperative analgesia during their stay. One patient in the MED group had a dural tear. CONCLUSION: MED is at least as effective as microsurgical discectomy for treatment of uncontained or large contained disc herniations, although the advantages over the open technique are short lived and did not reach significance. Nonetheless, for the surgeon accustomed to endoscopic techniques, MED seems to be a safe procedure.