Commitment toward the natural T (iNKT) cell lineage occurs at the CD4+8+ stage of thymic ontogeny

T lineage commitment occurs in a discrete, stage-specific manner during thymic ontogeny. Intrathymic precursor transfer experiments and the identification of CD4(+)8+ double-positive (DP), V alpha 14J alpha 18 natural T (iNKT) cells suggest that commitment to this lineage might occur at the DP stage. Nevertheless, this matter remains contentious because others failed to detect V alpha 14J alpha 18-positive iNKT cells that are CD4(+)8+. In resolution to this issue, we demonstrate that retinoic acid receptor-related orphan receptor gamma (ROR gamma)0/0 thymi, which accumulate immature single-positive (ISP) thymocytes that precede the DP stage, do not rearrange V alpha 14-to-J alpha 18 gene segments, suggesting that this event occurs at a post-ISP stage. Mixed radiation bone marrow chimeras revealed that RORgamma functions in an iNKT cell lineage-specific manner. Further, introgression of a Bcl-x(L) transgene into ROR gamma(0/0) mice, which promotes survival and permits secondary rearrangements of distal V alpha and J alpha gene segments at the DP stage, rescues V alpha 14-to-J alpha 18 recombination. Similarly, introgression of a rearranged V alpha 14J alpha 18 transgene into ROR gamma(0/0) mice results in functional iNKT cells. Thus, our data support the "T cell receptor-instructive (mainstream precursor) model" of iNKT cell lineage specification where V alpha 14-to-J alpha 18 rearrangement, positive selection, and iNKT cell lineage commitment occur at or after the DP stage of ontogeny.     

The causes of total knee arthroplasty failure: Avoiding your next revision

This article is a personal retrospective of the author׳s more than 35 years of experience as an arthroplasty surgeon and specifically addresses how to avoid revision total knee arthroplasty.

• 1.Avoid revision surgery if the patient is satisfied, unless imminent danger of prosthetic failure appears.
• 2.Use proper technique at the primary arthroplasty to avoid the problems of aseptic loosening, instability, malalignment, and infection that force most revisions. Scrupulous attention to detail in patient selection and operative technique at the primary surgery will help avert revision surgery.
• 3.Remember that surgical technique is prosthesis specific. Understanding the design and insertion philosophy of each implant is crucial to success; every implant system is different.
• 4.Strive to understand the underlying reason that an arthroplasty has failed to make a patient satisfied and fix the problem at revision. If the reason for revision is unclear, it is unlikely that surgery will make the patient better.
• 5.Avoid revision surgery if the problem is pain with no identifiable, surgically correctable problem.
• 6.Maintain strict selection criteria for obese patients, who have higher prevalence of problems that can lead to total knee revision. Surgeons who operate on obese patients likely will have more revision cases. Often, however, obese patients have gratifying results in terms of pain relief and improved function.

     

Revision Surgery for Failed Cervical Spine Reconstruction: Review Article

Background

As the number of cervical spine procedures performed continues to increase, the need for revision surgery is also likely to increase. Surgeons need to understand the etiology of post-surgical changes, as well as have a treatment algorithm when evaluating these complex patients.

Questions/Purposes

This study aims to review the rates and etiology of revision cervical spine surgery as well as describe our treatment algorithm.

Methods

We used a narrative and literature review. We performed a MEDLINE (PubMed) search for “cervical” and “spine” and “revision” which returned 353 articles from 1993 through January 22, 2014. Abstracts were analyzed for relevance and 32 articles were reviewed.

Results

The rates of revision surgery on the cervical spine vary by the type and extent of procedure performed. Patient evaluation should include a detailed history and review of the indication for the index procedure, as well as lab work to rule out infection. Imaging studies including flexion/extension radiographs and computed tomography are obtained to evaluate potential pseudarthrosis. Magnetic resonance imaging is helpful to evaluate the disc, neural elements, soft tissue, and to differentiate scar from infection. Sagittal alignment should be corrected if necessary.

Conclusions

Recurrent or new symptoms after cervical spine reconstruction can be effectively treated with revision surgery after identifying the etiology, and completing the appropriate workup.

Electronic supplementary material

The online version of this article (doi:10.1007/s11420-014-9394-8) contains supplementary material, which is available to authorized users.     

Does joint line elevation after revision knee arthroplasty affect tibio-femoral kinematics,contact pressure or collateral ligament lengths? An in vitro analysis

Introduction

Correct restoration of the joint line is generally considered as crucial when performing total knee arthroplasty (TKA). During revision knee arthroplasty however, elevation of the joint line occurs frequently. The general belief is that this negatively affects the clinical outcome, but the reasons are still not well understood.

Material and methods

In this cadaveric in vitro study the biomechanical consequences of joint line elevation were investigated using a previously validated cadaver model simulating active deep knee squats and passive flexion-extension cycles. Knee specimens were sequentially tested after total knee arthroplasty with joint line restoration and after 4 mm joint line elevation.

Results

The tibia rotated internally with increasing knee flexion during both passive and squatting motion (range: 17° and 7° respectively). Joint line elevation of 4 mm did not make a statistically significant difference. During passive motion, the tibia tended to become slightly more adducted with increasing knee flexion (range: 2°), while it went into slighlty less adduction during squatting (range: –2°). Neither of both trends was influenced by joint line elevation. Also anteroposterior translation of the femoral condyle centres was not affected by joint line elevation, although there was a tendency for a small posterior shift (of about 3 mm) during squatting after joint line elevation. In terms of kinetics, ligaments lengths and length changes, tibiofemoral contact pressures and quadriceps forces all showed the same patterns before and joint line elevation. No statistically significant changes could be detected.

Conclusions

Our study suggests that joint line elevation by 4 mm in revision total knee arthroplasty does not cause significant kinematic and kinetic differences during passive flexion/extension movement and squatting in the tibio-femoral joint, nor does it affect the elongation patterns of collateral ligaments. Therefore, clinical problems after joint line elevation are probably situated in the patello-femoral joint or caused by joint line elevation of more than 4 mm.     

Comparison between the SCL-90-R and MMPI in TMD patients with psychological problems

Oral Diseases (2012) 18 , 140–146 Objective: The aim of the study was to investigate the relationships between the Symptom Checklist‐90‐Revision (SCL‐90‐R) and the Minnesota Multiphasic Personality Inventory (MMPI) in temporomandibular disorders (TMD) patients with psychological problems. Materials and Methods: Subjective symptoms, objective signs, and psychological characteristics of 36 TMD patients with psychological problems were analyzed. The symptom severity index (SSI) and craniomandibular index (CMI) were used to assess subjective symptoms and objective signs of patients with TMD, respectively. The SCL‐90‐R and MMPI were used for psychological evaluation. Results: The SSI was not significantly correlated with the CMI in TMD patients with psychological problems, and these indices displayed significant correlations with the SCL‐90‐R and MMPI in several selected subscales. The results of SCL‐90‐R had a limited relationship with those of MMPI in these patients. Based on the MMPI diagnosis, the SCL‐90‐R somatization subscale showed moderate to high sensitivity and specificity, but the SCL‐90‐R depression subscale showed moderate to low sensitivity and specificity. Conclusions: Considering the limited relationship between the SCL‐90‐R and MMPI in TMD patients with psychological problems, more comprehensive psychological tests are recommended when clinicians suspect patients with TMD of having accompanying psychological problems.     

Complications in lumbar spine surgery: A retrospective analysis

Background:

Surgical treatment of adult lumbar spinal disorders is associated with a substantial risk of intraoperative and perioperative complications. There is no clearly defined medical literature on complication in lumbar spine surgery. Purpose of the study is to retrospectively evaluate intraoperative and perioperative complications who underwent various lumbar surgical procedures and to study the possible predisposing role of advanced age in increasing this rate.

Materials and Methods:

From 2007 to 2011 the number and type of complications were recorded and both univariate, (considering the patients’ age) and a multivariate statistical analysis was conducted in order to establish a possible predisposing role. 133 were lumbar disc hernia treated with microdiscetomy, 88 were lumbar stenosis, treated in 36 cases with only decompression, 52 with decompression and instrumentation with a maximum of 2 levels. 26 patients showed a lumbar fracture treated with percutaneous or open screw fixation. 12 showed a scoliotic or kyphotic deformity treated with decompression, fusion and osteotomies with a maximum of 7.3 levels of fusion (range 5-14). 70 were spondylolisthesis treated with 1 or more level of fusion. In 34 cases a fusion till S1 was performed.

Results:

Of the 338 patients who underwent surgery, 55 showed one or more complications. Type of surgical treatment (P = 0.004), open surgical approach (open P = 0.001) and operative time (P = 0.001) increased the relative risk (RR) of complication occurrence of 2.3, 3.8 and 5.1 respectively. Major complications are more often seen in complex surgical treatment for severe deformities, in revision surgery and in anterior approaches with an occurrence of 58.3%. Age greater than 65 years, despite an increased RR of perioperative complications (1.5), does not represent a predisposing risk factor to complications (P = 0.006).

Conclusion:

Surgical decision-making and exclusion of patients is not justified only by due to age. A systematic preoperative evaluation should always be performed in order to stratify risks and to guide decision-making for obtaining the best possible clinical results at lower risk, even for elderly patients.     

Results of Wagner SL revision stem with impaction bone grafting in revision total hip arthroplasty

Background:

As the number of total hip arthroplasties (THAs) performed increases, so do the number of required revisions. Impaction bone grafting with Wagner SL Revision stem is a good option for managing bone deficiencies arising from aseptic osteolysis. We studied the results of cementless diaphyseal fixation in femoral revision after total hip arthroplasty and whether there was spontaneous regeneration of bone stock in the proximal femur after the use of Wagner SL Revision stem (Zimmer, Warsaw, IN, USA) with impaction bone grafting.

Materials and Methods:

We performed 53 hip revisions using impaction bone grafting and Wagner SL Revision stems in 48 patients; (5 cases were bilateral) for variety of indications ranging from aseptic osteolysis to preiprosthetic fractures. The average age was 59 years (range 44-68 years). There were 42 male and 6 female patients. Four patients died after surgery for reasons unrelated to surgery. 44 patients were available for complete analysis.

Results:

The mean Harris Hip Score was 42 before surgery and improved to 86 by the final followup evaluation at a mean point of 5.5 years. Of the 44 patients, 87% (n=39) had excellent results and 10% (n=5) had good results. The stem survival rate was 98% (n=43).

Conclusion:

Short term results for revision THA with impaction bone grafting and Wagner SL revision stems are encouraging. However, it is necessary to obtain long term results through periodic followup evaluation, as rate of complications may increase in future.