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AimsThe aim of this study was to determine whether chilled irrigation saline decreases the incidence of clinical upper limb palsy (ULP; a reduction of one grade or more on manual muscle testing; MMT), based on the idea that ULP results from thermal damage to the nerve roots by heat generated by friction during bone drilling.MethodsIrrigation saline for drilling was used at room temperature (RT, 25.6°C) in open-door laminoplasty in 400 patients (RT group) and chilled to a mean temperature of 12.1°C during operations for 400 patients (low-temperature (LT) group). We assessed deltoid, biceps, and triceps brachii muscle strength by MMT. ULP occurring within two days post-operatively was categorised as early-onset palsy.ResultsThe incidence of ULP (4.0% vs9.5%, p = 0.003), especially early-onset palsy (1.0% vs5.5%, p < 0.001), was significantly lower for the LT group than for the RT group. Multivariate analysis indicated that RT irrigation saline use, concomitant foraminotomy, and opened side were significant predictors for ULP.DiscussionUsing chilled irrigation saline during bone drilling significantly decreased the ULP incidence, particularly the early-onset type, and shortened the recovery period for ULP. Chilled irrigation saline can thus be recommended as a simple method for preventing ULP.Take home message: Chilled irrigation during laminoplasty reduces C5 palsy.Cite this article: Bone Joint J2016;98-B:117–24.

Abnormal activation of SETBP1through overexpression or missense mutations is highly recurrent in various myeloid malignancies; however, it is unclear whether such activation alone is able to induce leukemia development. Here we show that Setbp1overexpression in mouse bone marrow progenitors through retroviral transduction is capable of initiating leukemia development in irradiated recipient mice. Before leukemic transformation, Setbp1overexpression significantly enhances the self-renewal of hematopoietic stem cells (HSCs) and expands granulocyte macrophage progenitors (GMPs). Interestingly, Setbp1overexpression also causes transcriptional repression of critical hematopoiesis regulator gene Runx1and this effect is crucial for Setbp1-induced transformation. Runx1repression is induced by Setbp1-mediated recruitment of a nucleosome remodeling deacetylase (NuRD) complex to Runx1promoters and can be reversed by treatment with histone deacetylase (HDAC) inhibitors Entinostat and Vorinostat. Moreover, treatment with these inhibitors caused efficient differentiation of Setbp1activation-induced leukemia cells in vitro, and significantly extended the survival of mice transplanted with such leukemias, suggesting that HDAC inhibition could be an effective strategy for treating myeloid malignancies with SETBP1activation.

Using the transverse processes of fresh porcine lumbar spines as an experimental model we evaluated the heat generated by a rotating burr of a high-speed drill in cutting the bone. The temperature at the drilled site reached 174°C with a diamond burr and 77°C with a steel burr. With water irrigation at a flow rate of 540 ml/hr an effective reduction in the temperature was achieved whereas irrigation with water at 180 ml/hr was much less effective. There was a significant negative correlation between the thickness of the residual bone and the temperature measured at its undersurface adjacent to the drilling site (p < 0.001). Our data suggest that tissues neighbouring the drilled bone, especially nerve roots, can be damaged by the heat generated from the tip of a high-speed drill. Nerve-root palsy, one of the most common complications of cervical spinal surgery, may be caused by thermal damage to nerve roots arising in this manner.

We evaluated 30 patients with cervical myelopathy before and after decompressive surgery and compared them with 42 healthy controls. All were asked to grip and release their fingers as rapidly as possible for 15 seconds. Films recorded with a digital camera were divided into three files of five seconds each. Three doctors independently counted the number of grip and release cycles in a blinded manner (N1 represents the number of cycles for the first five-second segment, N2 for the second and N3 for the third). N2 and N3 of the pre-operative group were significantly fewer than those of the control group, and the postoperative group’s results were significantly greater than those of the pre-operative group. In the control group, the numbers decreased significantly with each succeeding five-second interval (fatigue phenomenon). In the pre-operative myelopathy group there was no significant difference between N1 and N2 (freezing phenomenon).The 15-second test is shown to be reliable in the quantitative evaluation of cervical myelopathy. Although it requires a camera and animation files, it can detect small changes in neurological status because of its precise and objective nature.

In order to clarify the risk of cancer development in patients with rheumatoid arthritis (RA), the incidence of malignant tumors during a follow-up period was investigated in RA patients at the Center for Adult Diseases, Osaka, Japan. Six hundred and fifty-five eligible rheumatoid patients (131 males, 524 females) who were admitted to our institute between 1980 and 1989 were matched against the files of the Osaka Cancer Registry. Among them, a total of 26 patients (5 males, 21 females) were noted to have developed some kinds of cancer. The female RA patients demonstrated a significantly higher incidence of all cancers than the general population, with an observedexpected (OE) ratio of 1.71 (95% confidence interval = 1.06-2.62). Cancer of the buccal cavity /pharynx and thyroid cancer also showed a higher incidence in female RA patients, with O/E ratios of 12.93 and 2.74, respectively.