Trapping and Ground-State Cooling of a Single H_{2}

We demonstrate co-trapping and sideband cooling of a H_{2}^{+}-^{9}Be^{+} ion pair in a cryogenic Paul trap. We study the chemical lifetime of H_{2}^{+} and its dependence on the apparatus temperature, achieving lifetimes of up to 11_{-3}^{+6} h at 10 K. We demonstrate cooling of two of the modes of translational motion to an average phonon number of 0.07(1) and 0.05(1), corresponding to a temperature of 22(1) and 55(3) µK, respectively. Our results provide a basis for quantum logic spectroscopy experiments of H_{2}^{+}, as well as other light ions such as HD^{+}, H_{3}^{+}, and He^{+}.

Impaction bone grafting for the reconstruction of large bone defects in revision knee arthroplasty.

OBJECTIVE: Regeneration of autologous bone stock and formation of a stable implant bed by impaction of morselized bone allograft. INDICATIONS: Bone loss after septic and aseptic loosening or tumour resection. CONTRAINDICATIONS: Persistent infection, one-stage septic revision, poor therapeutic compliance, extensive uncontained metaphyseal defects with cortical thinning of the diaphysis. SURGICAL TECHNIQUE: Whilst the surgeon removes the loose prosthesis, the assistant prepares the graft. The medullary canal is sealed with a cement restrictor. Graft particles of different sizes are densely impacted around a trial stem. The highest level of stability is achieved by using large particles interspersed with small filler particles. Low-viscosity cement facilitates cement penetration and ensures strong interdigitation with the impacted graft mass after implantation of the prosthesis. Uncontained metaphyseal defects are treated with prosthetic augments. POSTOPERATIVE MANAGEMENT: Gait training, physiotherapy with isometric quadriceps exercises, partial weight-bearing for 6 weeks, resistance training begins 8 weeks postoperatively. RESULTS: Between 2010 and 2012, 28 patients with large bone defects [Anderson Orthopaedic Research Institute (AORI) grade: 21 × F3, 3 × F2, 13 × T3, 8 × T2] underwent total knee revision with impaction bone grafting. The mean follow-up was 27.7 months (range 21-47 months). On average, patients had undergone 2.5 previous revisions. Implant survival was 82.0 % (95 % CI = 62.5 %-92.1 %) for any reason of revision as the endpoint and 93.1 % (95 % CI = 74.5-98.4 %) for aseptic revision as the endpoint. The mean postoperative Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score was 35.4 (range 3.3-101.6, SD ± 26.2). The mean KSS was 70.6 (range 20-100, SD ± 26.8).

[Open biopsy of bone and soft tissue tumors : guidelines for precise surgical procedures]. / Offene biopsie von knochen- und weichteiltumoren : richtlinien für ein korrektes chirurgisches vorgehen.

OBJECTIVE: The objective of an open biopsy is to obtain a sufficient amount of representative tumor tissue in terms of adequate quality and quantity, without adverse effects on later therapy. INDICATIONS: Suspected malignancy after non-invasive diagnostic procedures. Histopathologic evaluation of tumor entity and grading. Planning of the definitive tumor resection and initiation of neoadjuvant therapeutic regimen. Obtaining unfixed, fresh-frozen tumor samples for molecular/genetic analyses or tumor tissue bank. CONTRAINDICATIONS: Hemorrhagic diathesis. Tumor is only accessible with a surgical approach leading to a significant damage of the surrounding tissue. High probability of tumor cell contamination with incisional biopsy. Poor physical status. Poor therapeutic compliance. SURGICAL TECHNIQUE: The biopsy tract should be carefully planned according to oncological principles. The operation begins with a small incision in longitudinal direction to the extremity. The shortest path between skin and lesion that avoids contamination of other compartments is selected. The biopsy tract should be located within the surgical approach which is later used for definitive tumor resection. During the definitive procedure it should be possible to resect the biopsy approach with adequate surgical margins because it is considered to be contaminated with tumor cells. In principle, a wide resection of the biopsy tract should be possible. During the operation meticulous hemostasis has to be performed because any hematoma around a tumor may contaminate the entire extremity. In cases of an intraosseous tumor a cortical window should be made to obtain intramedullary tumor tissue. Drains should be located in continuity with the skin incision or in direct extension of the wound. Wound closure with intracutaneous suture technique. Excisional biopsy in terms of marginal resection should be performed only in the presence of small, epifascial lesions that are assumed to be benign after completion of basic diagnostic procedures. In cases of larger or subfascial tumors an incisional biopsy should be conducted. POSTOPERATIVE MANAGEMENT: Compressive dressing to prevent postoperative hematoma. In cases of tumors affecting load-bearing bones, weight-bearing should be prohibited after biopsy, if there is any fracture risk. Upon receipt of the histopathological results the definitive tumor resection is planned.

[Nerve lesions after minimally invasive total hip arthroplasty]. / Nervenläsionen nach minimal-invasiver Hüftendoprothetik.

Although there is no clear evidence, minimally invasive hip arthroplasty seems to be associated with slightly higher complication rates compared to standard procedures. Major nerve palsy is one of the least common but most distressing complications. The key for minimizing the incidence of nerve lesions is to analyze preoperative risk factors, accurate knowledge of the anatomy and minimally invasive techniques. Once clinical signs of nerve injury are evident, the first diagnostic steps are localization of the lesion and quantification of the damage pattern. Therefore, clinical assessment of the neurological deficits should be performed as soon as possible. Apart from rare cases of isolated transient conduction blockade or complete transection, the damage pattern is mostly combined. Thus, there can be evidence for dysfunction of nerve conduction (neuropraxia) and structural nerve damage (axonotmesis or neurotmesis) simultaneously. Because the earliest signs of denervation are detectable via electromyography after 1 week, it is not possible to make any reliable prognosis within the first days after nerve injury using electrophysiological methods. This review article should serve as a guideline for prevention, diagnostics and therapy of neural lesions in minimally invasive hip arthroplasty.