Parathyroid hormone-related protein regulates proliferation of condylar hypertrophic chondrocytes.

The condylar cartilage, an important growth site in the mandible, shows characteristic modes of growth and differentiation, e.g., it shows delayed appearance in development relative to the limb bud cartilage, originates from the periosteum rather than from undifferentiated mesenchymal cells, and shows rapid differentiation into hypertrophic chondrocytes as opposed to the epiphyseal growth plate cartilage, which has resting and proliferative zones. Recently, attention has been focused on the role of parathyroid hormone-related protein (PTHrP) in modulating the proliferation and differentiation of chondrocytes. To investigate further the characteristic modes of growth and differentiation of this cartilage, we used mice with a disrupted PTHrP allele. Immunolocalization of type X collagen, the extracellular matrix specifically expressed by hypertrophic chondrocytes, was greatly reduced in the condylar cartilage of homozygous PTHrP-knockout mice compared with wild-type mice. In contrast, immunolocalization of type X collagen of the tibial cartilage did not differ. In wild-type mice, proliferative chondrocytes were mainly located in both the flattened cell layer and hypertrophic cell layer of the condylar cartilage, but were limited to the proliferative zone of the tibial cartilage. The number of proliferative chondrocytes was greatly reduced in both cartilages of homozygous PTHrP-knockout mice. Moreover, apoptotic chondrocytes were scarcely observed in the condylar hypertrophic cell layer, whereas a number of apoptotic chondrocytes were found in the tibial hypertrophic zone. Expression of the type I PTH/PTHrP receptor was localized in the flattened cell layer and hypertrophic cell layer of the condylar cartilage, but was absent from the tibial hypertrophic chondrocytes. It is therefore concluded that, unlike tibial hypertrophic chondrocytes, condylar hypertrophic chondrocytes have proliferative activity in the late embryonic stage, and PTHrP plays a pivotal role in regulating the proliferative capacity and differentiation of these cells.     

Bowel Obstruction after Laparoscopic Roux-en-Y Gastric Bypass

Background: Bowel obstruction has been frequently reported after laparoscopic Roux-en-Y gastric bypass (LRYGBP). The aim of this study was to review our experience with bowel obstruction following LRYGBP, specifically examining its etiology and management and to strategize maneuvers to minimize this complication. Methods: We retrospectively reviewed the charts of 9 patients who developed postoperative bowel obstruction after LRYGBP. Each chart was reviewed for demographics, timing of bowel obstruction from the primary operation, etiology of obstruction, and management. Results: 9 of our initial 225 patients (4%) who underwent LRYGBP developed postoperative bowel obstruction. The mean age was 46 ± 12 years, with mean BMI 47 ± 9 kg/m². 6 patients developed early bowel obstruction, and 3 patients developed late bowel obstruction. The mean time interval for development of early bowel obstruction was 16 ±16 days. The causes for early bowel obstruction included narrowing of the jejunojenunostomy anastomosis (n=3), angulation of the Roux limb (n=2), and obstruction of the Roux limb at the level of the transverse mesocolon (n=1). The mean time interval for development of late bowel obstruction was 7.4 ± 0.5 months. The causes for late bowel obstruction included internal herniation (n=2) and adhesions (n=1). 6 of 9 bowel obstructions (66%) were considered technically related to the learning curve of the laparoscopic approach. Eight of the 9 patients required operative intervention, and 6 of the 8 reoperations were managed laparoscopically. Management included laparoscopic bypass of the jejunojejunostomy obstruction site (n=5), open reduction of internal hernia (n=2), and laparoscopic lysis of adhesion (n=1). Conclusions: Bowel obstruction is a frequent complication after LRYGBP, particularly during the learn ing curve of the laparoscopic approach. Specific measures should be instituted to minimize bowel obstruction after LRYGBP as most of these complications are considered technically preventable.     

Coronary artery vasospasm causing acute myocardial infarction in a heart transplant recipient.

The etiology of cardiac allograft vasculopathy is not known, but may be preceded by both endothelial cell and smooth muscle dysfunction of the epicardial coronary arteries. We here report a case of acute, reversible coronary artery vasospasm which caused a myocardial infarction in a cardiac transplant recipient. The patient had a complex post-transplant course, including an episode of severe vascular rejection several months before this presentation. Interestingly, the event was captured in its early stages because the patient presented with chest pain: a rare event because of the denervation of the transplanted heart. Our ability to document the etiology of this patient's myocardial infarction supports the concept that cardiac allograft vasculopathy is a progressive disease that, in its early stages, may include a reversible component of abnormal vasoreactivity.     

Accuracy of axillary MR imaging in treated breast cancer for distinguishing between recurrent tumour and treatment effects: does intravenous Gd-DTPA enhancement help in cases of diagnostic dilemma?

AIM: To evaluate the sensitivity and specificity of axillary magnetic resonance imaging (MRI) in symptomatic patients, who had previously been treated for breast cancer, compared with clinical outcome after a minimum of 1 year.METHODS: One hundred and five patients underwent axillary MRI examinations and were diagnosed as axillary tumour, metastatic tumour, treatment effect or normal. RESULTS: At MRI, 48 patients had axillary tumour, 51 had metastatic tumour (37 had both), 27 had treatment effect and 22 were normal. At outcome (median follow-up, 484 days), 54 patients were positive for axillary tumour, 59 for metastatic disease (40 had both), 21 had treatment effect alone and 18 were clear. Magnetic resonance imaging showed 89% sensitivity, 100% specificity and 94% accuracy for recurrent axillary tumour, and 85% sensitivity, 98% specificity and 90% accuracy for metastatic tumour. Soft tissue plaques were the commonest axillary disease pattern seen (37). Small volume soft tissue plaques gave the most diagnostic difficulty. Non-dynamic enhancement with intravenous Gadopentetate dimeglumine (Gd-DTPA) in a subset of 34 patients improved sensitivity for axillary tumour from 40 to 74%, and improved diagnostic confidence in 11 patients (32%). Magnetic resonance imaging had a positive management impact leading to treatment alteration in 45 patients, 43 of whom had recurrent axillary and/or metastatic tumour.CONCLUSIONS: Tumour plaques were the commonest pattern of recurrent axillary disease. Forty-eight percent of the patients had metastatic deposits identified by MRI. Magnetic resonance imaging had excellent specificity (100%) and good sensitivity (89%) for recurrent axillary tumour compared with outcome at 1 year, which was improved by non-dynamic administration of Gd-DTPA in 32% of the subset who received it.     

Conversion from extracorporeal membrane oxygenation to total cardiopulmonary bypass: a simplified method

Pediatric patients who have preoperative hemodynamic instability or postoperative cardiac decompensation may frequently require the use of extracorporeal membrane oxygenation (ECMO) for stabilization of cardiac and respiratory function. While ECMO can be a therapeutic treatment for the congenital pediatric patient, it does not allow the additional functions of a complete cardiopulmonary bypass (CPB) circuit should subsequent surgical revision in the operating room be required. This paper will discuss our approach to converting the ECMO circuit to total cardiopulmonary bypass allowing the use of cardioplegia, cardiotomy suction, and modified ultrafiltration. This technique allows the conversion to CPB without ceasing support to the critically ill patient or exposing them to additional blood products or surface area in the priming of a new extracorporeal circuit. In addition, this circuit design allows for the resumption of ECMO support utilizing the same circuit if the patient necessitates it.     

Surgeon experience and clinical and economic outcomes for shoulder arthroplasty

BACKGROUND: Previous studies have demonstrated that a high surgical volume for certain surgical procedures reduces morbidity and improves economic outcome; however, to our knowledge, no study has demonstrated a similar relationship between volume and outcome for total shoulder arthroplasty and hemiarthroplasty. The objective of this study was to determine whether increased surgeon experience was associated with improved clinical and economic outcomes for patients undergoing total shoulder arthroplasty or hemiarthroplasty. METHODS: We analyzed discharge data on patients treated between 1994 and 2000 from the Maryland Health Services Cost Review Commission, which has a statewide hospital discharge database of all patients in the state of Maryland. The database included all patients undergoing total shoulder arthroplasty and hemiarthroplasty. We assessed the relationship between surgeon volume (low, medium, and high) and the risk of complications, length of stay, and total charges. The statistics were adjusted for procedure, age, gender, race, marital status, comorbidity, diagnosis, insurance type, income, and hospital volume. RESULTS: For the 1868 discrete total shoulder arthroplasties and hemiarthroplasties done in the state of Maryland, the risk of at least one complication associated with the procedures done by the high-volume surgeon group was nearly half that associated with the procedures done by the low-volume surgeon group (adjusted odds ratio, 0.6; 95% confidence interval, 0.4 to 0.9). High-volume surgeons were three times more likely than were low-volume surgeons to have patients with a hospital stay of less than six days (odds ratio, 0.3; 95% confidence interval, 0.2 to 0.6). Although the average cost of hospitalization was $1000 less in the high-volume surgeon group compared with the low-volume surgeon group, this reduction did not reach significance after adjustment for multiple variables (odds ratio, 0.8; 95% confidence interval, 0.5 to 1.4). CONCLUSIONS: This study indicates that the patients of surgeons with higher average annual caseloads of total shoulder arthroplasties and hemiarthroplasties have decreased complication rates and hospital lengths of stay compared with the patients of surgeons who perform fewer of these procedures. These analyses of hospital discharge data are limited because of a lack of prospective data, operative details, and patient outcomes data. However, this study emphasizes the importance of continued education for orthopaedic surgeons who perform shoulder arthroplasty.     

Parathyroid exploration in the reoperative neck: improved preoperative localization with 4D-computed tomography

BACKGROUND: Reoperation for hyperparathyroidism (HPT) carries an increased risk for morbidity and failure to cure. Accurate preoperative localization minimizes operative risk but is often difficult to achieve in the reoperative setting. Four-dimensional computed tomography (4D-CT) is an emerging technique that uses functional parathyroid anatomy for precise preoperative localization. We evaluated 4D-CT as a tool for localization of hyperfunctioning parathyroid tissue in the reoperative setting. STUDY DESIGN: A prospective endocrine database was queried to identify 45 patients who underwent reoperative parathyroidectomy after preoperative localization using 4D-CT. The patients were categorized into 1 of 3 groups: group 1 included those who had previous neck surgery for non-HPT conditions; group 2 included those who had undergone a previously unsuccessful neck exploration for HPT; and group 3 included patients with HPT who had a previous neck exploration with resection of at least 1 hypercellular parathyroid. RESULTS: The sensitivity of 4D-CT for localization was 88% compared with 54% for sestamibi imaging. Four-dimensional CT more often correctly localized (p=0.0003) and lateralized (p=0.005) hyperfunctional parathyroid tissue than sestamibi did. Four-dimensional CT successfully localized hyperfunctional parathyroid tissue in 18 (82%) of 22 group 1 patients, 10 (91%) of 11 group 2 patients, and 8 (67%) of 12 group 3 patients. Three patients were lost to followup. At a mean followup of 9.8 months, 39 (93%) of 42 patients were surgically cured and 3 patients (7%; 2 in group 3) had persistent HPT. CONCLUSIONS: Four-dimensional-CT is an ideal tool for preoperative localization of hyperfunctioning parathyroid tissue in the reoperative setting. Localization and successful reoperation are most difficult in patients who have undergone an earlier operation that included resection of at least one hypercellular parathyroid suggesting multigland disease.