Anatomy and pathomechanics of ring and small finger carpometacarpal joint injuries

PURPOSE: The purpose of this study was to detail the pathomechanics and pathoanatomy of fracture dislocations of the ring finger and small finger carpometacarpal (CMC) joint by duplicating the pathomechanics of the fist blow. METHODS: A custom-made jig was used to position 20 fresh-frozen cadaver upper extremities in forearm neutral rotation, 90 degrees of elbow flexion, 20 degrees of wrist extension, and 20 degrees and 30 degrees of flexion at the ring and small finger CMC joint, respectively. First 7.7 kg of weight were dropped from a height of 0.76 m to 1.1 m to axially load the ring and small metacarpal (MC) heads through a custom-made apparatus. Fluoroscopic examination before and after loading, and detailed dissection after loading, were used to identify any osseous and/or ligamentous injuries. RESULTS: The most common fractures were a dorsal capitate fracture and a middle MC dorsal base fracture. The most common combinations of fractures were the dorsal capitate and dorsal hamate fractures. Multiple fractures often were identified in a number of locations including dorsally: the capitate, hamate, and index through small metacarpal bases, and volarly: the hook of the hamate and the middle through the small MC bases. CONCLUSIONS: The patterns of injuries encountered at the ring and small CMC joints can be explained by the direction and force of the applied load, position of the CMC joint at the time of loading, and the constraints imposed by specific CMC ligaments. A detailed analysis of the fracture patterns and associated ligament anatomy suggests that the typical ring and small carpometacarpal fracture dislocations are a more complex combination of fractures than identified by plain radiographs alone. The complexity of these injuries is greater than previously recognized and is most likely the result of a combination of axial load and shear stresses resulting in carpal fractures and ligament avulsions as well as fracture dislocations. This study suggests that computed tomography may be the preferred diagnostic imaging method for complete assessment of these injuries.     

Radial artery as conduit for distal renal artery reconstruction

Reconstruction of the renal artery with both saphenous vein and prosthetic material as bypass graft is durable in atherosclerotic disease. Extensive experience with saphenous vein grafts in pediatric patients and patients without atherosclerosis reveals a disturbing incidence of vein graft aneurysm degeneration. Distal renal artery reconstruction involving small branch vessels is generally not amenable to prosthetic reconstruction. We report a new approach to distal renal artery bypass grafting to avert these limitations. CASE: A 43-year-old man with previously normal blood pressure had malignant hypertension, which proved difficult to control despite use of a beta-blocker and an angiotensin II inhibitor. At renal angiography a fusiform aneurysm was revealed in a posterior branch of the right renal artery. The renal artery aneurysm was resected, and the left radial artery was harvested and used as a sequential aortorenal bypass graft to the two branch renal arteries. The postoperative course was uneventful, and the patient now has normal blood pressure with a calcium channel blocker for maintenance of the radial artery graft. Pathologic analysis revealed a pseudoaneurysm with dissection between the media and external lamella, consistent with fibromuscular dysplasia. CONCLUSION: Autologous artery is the preferred conduit for renal reconstruction in the pediatric population. On the basis of cardiac surgery experience, we used the radial artery and found it to be a technically satisfactory conduit for distal renal reconstruction in a patient without atherosclerosis.     

Risk factors for occult nodal metastasis in clinical T1N0 lung cancer: a negative impact on survival

BACKGROUND: The application of CT imaging has increased the identification of patients with clinical T1N0 (cT1N0) lung cancer. The optimal management strategy for these early stage lung cancers remains unclear. We analyzed the impact of occult nodal metastasis on cT1N0 lung cancer patients. METHODS: We studied patients with cT1N0 lung cancer enrolled in our database from January 1995 to December 2002. Preoperative staging was confirmed by review of CT and PET scan studies. Pathology specimens were reviewed. Multivariate analysis was performed to determine the risk of occult nodal involvement. Kaplan-Meier method was applied to analyze survival. RESULTS: Two hundred and ninety-seven patients with cT1N0 disease were identified. Fifty-eight percent of patients were pathological T1N0. Overall, 15% of patients had occult nodal metastasis. Logistic regression analysis demonstrated a three-fold increase in the risk of having pathologic stage II or stage III disease with every 1.0 cm increase in tumor size (odds ratio 3.2; 95% CI: 2.3-4.6). Multivariate analysis demonstrated tumor size to be a significant predictor of nodal metastasis (adjusted odds ratio 3.5; 95% CI: 2.4-5.1). Median survival was different between pathological stage I (96.3 months), stage II (41.4 months), and stage III (36.1 months) disease (p=0.002). CONCLUSION: Clinical T1N0 tumors are often understaged. The risk of occult nodal disease increases with tumor size, and this occult disease negatively impacts survival. Because of the limitations of clinical staging, we believe that lobectomy and lymph node analysis should be offered to cT1N0 lung cancer patients to provide accurate staging and to optimize multimodality adjuvant treatment of lung cancer.     

Cellular strategies for enhancement of fracture repair

Tissue engineering seeks to translate scientific knowledge into tangible products to advance the repair, replacement, or regeneration of organs and tissues. Current tissue engineering strategies have progressed recently from a historical approach that is based primarily on biomaterials to a cell and tissue-based approach that includes understanding of cell-sourcing and bioactive stimuli. New options include methods for harvest and transplantation of tissue-forming cells, bioactive matrix materials that act as tissue scaffolds, and delivery of bioactive molecules within scaffolds. These strategies are already benefiting patients, and they place increasing demands on orthopaedic surgeons to have a solid foundation in the contemporary concepts and principles of cell-based tissue engineering. Essentially all orthopaedic tissue engineering strategies can be distilled to a strategy or combination of strategies that seek to increase the number or relative performance of bone-forming cells. The global term connective tissue progenitors has been used to define the heterogeneous populations of stem and progenitor cells that are found in native tissue and that are capable of differentiating into one or more connective tissue phenotypes. These stem or progenitor populations are found in various tissue sources, with varying degrees of ability to differentiate along connective tissue lineages. Available cell-based strategies include targeting local cells with use of scaffolds or bioactive factors, or transplantation of autogenous connective tissue progenitor cells derived from bone marrow or other tissues, with or without processing to change their concentration or prevalence. The future may include means of homing circulating connective tissue progenitor cells with use of intrinsic chemokine systems, or modifying the biological performance of connective tissue progenitor cells by means of genetic modifications.     

Laparoscopic Reoperative Bariatric Surgery: Experience from 27 Consecutive Patients

Background: 10 to 25% of patients undergoing bariatric surgery will require a revision, either for unsatisfactory weight loss or for complications. Reoperation is associated with a higher morbidity and has traditionally been done in open fashion.The purpose of this study was to determine the safety and efficacy of reoperative surgery using a laparoscopic approach. Methods: A retrospective review of medical records over a 22-month period was conducted. 27 consecutive obesity surgery patients, who had undergone a laparoscopic revision, were identified. 26 of the 27 patients were women. The average age was 40.3 years (range 20 to 58 years) and average original preoperative body mass index (BMI) was 51.6 kg/m2 (range 42 to 66.5).The 27 primary bariatric operations consisted of vertical banded gastroplasty (12), gastric band placement (9) and gastric bypass (6). 17 of them were open procedures. After the primary surgery, the lowest average BMI was 37.6 kg/m² (range 21 to 52), which increased to 42.7 kg/m² (range 29 to 56) before reoperation. 24 of the 27 reoperations were indicated for insufficient weight loss. On average, revision was undertaken 52 months after the primary procedure (range 12 to 240 months). Results: 24 of the 27 laparoscopic reoperations were conversions to a gastric bypass. A second reoperation was indicated for insufficient weight loss on four occasions. In one case, conversion to open surgery was required. The average operative time was 232 ± 18.5 minutes (range 120 to 480) and length of hospital stay was 3.7 days (range 1 to 9). 22% percent of patients (6) experienced complications, including pneumothorax, gastric remnant dilation, gastrojejunostomy stenosis, port-site hernia and protein malnutrition. There was no mortality in the study.The average BMI was 35.9 kg/m² (range 27 to 45.5) 8 months after surgery (range 1 to 22 months). Compared with a preoperative BMI of 42.7 kg/m², the weight loss was statistically significant (p<0.001). Conclusion: Our results compare favorably with those reported for open reoperative bariatric surgery. A laparoscopic approach may be considered a feasible and safe alternative to an open operation.     

Sensitivity to acute insulin-mediated suppression of plasma free fatty acids is not a determinant of fasting VLDL triglyceride secretion in healthy humans

One important mechanism whereby obesity-associated insulin resistance leads to VLDL overproduction is thought to be by the increased flux of free fatty acids (FFAs) from extrahepatic tissues to liver, which arises as a direct consequence of impaired insulin action in adipose tissue and skeletal muscle. The aim of the present study was to address whether direct measures of peripheral tissue insulin sensitivity with regard to FFAs and glucose in the fasting state are good predictors of postabsorptive VLDL triglyceride secretion rate (VLDL-TG ASR) in humans, independent of obesity. Eighteen healthy control subjects, after an overnight fast, underwent three studies 3 weeks apart, in random order. Study 1: VLDL-TG levels, fractional clearance rate (per h), and VLDL-TG ASR were determined after an intravenous bolus of [1,1,2,3,3-(2)H(5)] glycerol. Study 2: Insulin sensitivity (S(I)), acute insulin response (AIR), and acute C-peptide response to glucose were assessed by frequently sampled intravenous glucose tolerance test using the minimal model approach. Study 3: Insulin-mediated suppression of plasma FFAs (k) and insulin clearance were assessed in response to a low-dose stepwise intravenous insulin infusion. BMI (R(2) = 0.54), AIR, and fasting insulin levels were positively and S(I) negatively correlated with VLDL-TG ASR, but there was no significant association with plasma FFAs or k. Only BMI remained significantly associated with VLDL-TG ASR in multivariate analysis. The best multivariate model for VLDL-TG ASR (R(2) = 0.61, P = 0.0008) included BMI (P = 0.0008) and S(I) (P = 0.12, inversely correlated). VLDL-TG secretion is predicted by BMI, independently of direct measures of insulin sensitivity. The sensitivity to insulin's acute suppressive effect on plasma FFA levels during fasting is not an important determinant of postabsorptive VLDL-TG secretion in humans.     

Early posttransplant inflammation promotes the development of alloimmunity and chronic human lung allograft rejection

BACKGROUND: Chronic human lung allograft rejection, represented by bronchiolitis obliterans syndrome (BOS), is the single most important factor that limits the long-term survival following lung transplantation (LT). However, the pathogenesis of BOS remains unclear. We hypothesized that the early posttransplant inflammation would promote the development of donor anti-human leukocyte antigen (HLA) alloimmunity and predispose to BOS. METHODS: Serum levels of interleukin (IL)-1beta, IL-2, IL-4, IL-5, IL-6, IL-7, IL-8, IL-10, IL-12, IL-13, IL-15, IL-17, Eotaxin, IP-10, MIG, MCP-1, MIP-1alpha, MIP-1beta, RANTES, tumor necrosis factor (TNF)-alpha, interferon (IFN)-alpha, IFN-gamma, granulocyte-macrophage colony-stimulating factor, IL-1Ralpha, and IL-2R were serially analyzed in 31 BOS+ and matched 31 BOS- patients using quantitative multiplex bead immunoassays. Donor-specific HLA class II cellular immunity was analyzed using enzyme-linked immunospot (ELISPOT) by testing recipient peripheral blood mononuclear cells against mismatched donor HLA-DR peptides. Anti-HLA class II antibodies were monitored using flow panel reactive antibodies. RESULTS: There was early posttransplant elevation in basal serum levels of proinflammatory chemokines IP-10 and MCP-1 and Th1-cytokines IL-1beta, IL-2, IL-12, and IL-15 in BOS+ patients, compared to BOS- and normal subjects. In addition, a threefold decline in IL-10 levels was found during BOS development. BOS+ patients revealed increased development of HLA class II alloantibodies and Th1-predominant donor-specific cellular immunity with high frequency of IFN-gamma and low IL-5 producing T-cells. CONCLUSION: Early posttransplant elevation of proinflammatory mediators is associated with alloimmunity and chronic human lung allograft rejection.     

p16INK4A immunohistochemistry is superior to HPV in situ hybridization for the detection of high-risk HPV in atypical squamous metaplasia

In situ hybridization (ISH) assays for high-risk human papillomavirus (HR-HPV) and immunohistochemical (IHC) assays for surrogate markers such as p16 can be useful in detecting HR-HPV in cervical dysplasia, but the use of these markers in problematic cervical biopsies has not been well-established. We evaluated 3 chromogenic ISH assays (Ventana INFORM HPVII and HPVIII and DakoCytomation GenPoint) in conjunction with p16 IHC and HPV polymerase chain reaction in a study set consisting of 12 low-grade squamous intraepithelial lesions, 16 high-grade squamous intraepithelial lesions, and 30 benign cervix samples. A test set of 28 cases of atypical squamous metaplasia were also evaluated withVentana HPVIII ISH and p16 IHC. In the study set, the sensitivity of the DakoCytomation ISH assay (which detects HPV subtypes 16, 18, 31, 33, 35, 39, 45, 52, 56, 58, 59, and 68) was similar to the Ventana HPVII assay but less than that of the Ventana HPVIII ISH assay (both of which detect HPV subtypes 16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, and 66) and less than p16 IHC (55.6% vs. 53.6 vs. 69.2% vs. 82.1%). All HPV ISH assays exhibited 100% specificity. p16 reactivity consisted of 2 patterns: focal strong and diffuse strong. Because focal strong p16 reactivity was identified in benign squamous epithelium (6.7% cases) and dysplastic epithelium, it was considered an equivocal result and only diffuse strong reactivity was considered to be specific for the presence of HR-HPV. In the squamous intraepithelial lesions study set, the difference in sensitivity between Ventana HPVIII ISH and p16 was not statistically significant. However, in the atypical squamous metaplasia test set cases, p16 reactivity (focal strong and diffuse strong) was significantly more sensitive than Ventana HPVIII ISH in correlating with the presence of human papillomavirus as detected by polymerase chain reaction (83.3% vs. 33.3% P=0.004). Because focal strong p16 reactivity is less specific, cases with this staining pattern are considered atypical and require further evaluation by other means. Overall, p16 IHC is considered the best candidate for the initial assessment of cervical biopsies that are histologically indeterminate for dysplasia given its wide availability, comparative ease of interpretation, and high sensitivity and specificity.