Stemmed femoral knee prostheses: Effects of prosthetic design and fixation on bone loss

Although the revision rates for modern knee prostheses have decreased drastically, the total number of revisions a year is increasing because many more primary knee replacements are being done. At the time of revision, bone loss is common, which compromises prosthetic stability. To improve stability, intramedullary stems are often used. The aim of this study was to estimate the effects of a stem, its diameter and the interface bonding conditions on patterns of the bone remodeling in the distal femur.

We created finite element models of the distal half of a femur in which 4 types of knee prostheses were placed. The bone remodeling process was simulated using a strain-adaptive bone remodeling theory. The amount of such remodeling was determined by calculating the changes in bone mineral density in 9 regions of interest from simulated DEXA scans.

The computer simulation model showed that revision prostheses tend to cause more bone resorption than primary ones, especially in the most distal regions. Predicted long-term bone loss due to a revision prosthesis with a thin stem equalled that around a prosthesis with an intercondylar box. However, strong regional differences were found- the stemmed prostheses having more bone loss in the most distal areas and some bone gain in the more proximal ones. A prosthesis with a thick stem led to an increase in bone loss. When the prosthesis-cement interface was bonded, more bone loss was predicted than with an unbonded interface. These results suggest that a stem which increases stability initially may reduce stability in the long term. This is due to an increase in stress shielding and bone resorption.     

Changes in bone mineral density, lean body mass and fat content as measured by dual energy x-ray absorptiometry in patients with prostate cancer without apparent bone metastases given androgen deprivation therapy

PURPOSE: We characterize the consequences of androgen deprivation therapy on body composition in elderly men. MATERIALS AND METHODS: Using a dual energy x-ray absorptiometry instrument, we determined the changes in bone mineral density, bone mineral content, fat body mass and lean body mass in 35 patients with prostate cancer without bone metastases who received luteinizing hormone releasing hormone analogue for 12 months. RESULTS: At baseline conditions 46% of cases were classified as osteopenic and 14% as osteoporotic at the lumbar spine and 40% were osteopenic and 4% osteoporotic at the hip. Androgen deprivation significantly decreased bone mineral density either at the lumbar spine (mean gm./cm.2 [SD] 1.00 [0.194], 0.986 [0.172] and 0.977 [0.182] at baseline, and 6 and 12 months, respectively, p <0.002) or the hip (0.929 [0.136], 0.926 [0.144] and 0.923 [0.138], p <0.03). A more than 2% decrease in bone mineral density was found at the lumbar spine in 19 men (54.3%) and at the hip in 15 (42.9%). Bone mineral content paralleled the bone mineral density pattern. Lean body mass decreased (mean gm. [SD] 50,287 [6,656], 49,296 [6,554] and 49,327 [6,345], p <0.003), whereas fat body mass consistently increased (18,115 [6,209], 20,724 [6,029] and 21,604 [5,923] p <0.001). CONCLUSIONS: Serial bone densitometry evaluation during androgen deprivation therapy may allow the detection of patients with prostate cancer at risk for osteoporotic fractures, that is those with osteopenia or osteoporosis at baseline and fast bone loss. The change in body composition may predispose patients to accidental falls, thus increasing the risk of bone fracture.     

Preoperative localization of indeterminate pulmonary nodules before videothoracoscopic resection

Background: The management of a solitary pulmonary nodule is the subject of debate and minimally invasive diagnostic approaches have low sensitivity for small peripheral nodules. We discuss the role of video-assisted thoracoscopic surgery (VATS) in the management of solitary pulmonary nodules (SPNs) ?1 cm performed with a preoperatory computed tomography-guided wire localization. Methods: Thirty-five selected patients underwent VATS resection for SPN, with localization by guide wire before surgery. Results: Seven patients, after VATS exploration, underwent thoracotomy because of pleuropulmonary adhesions, depth or dimensions. Histological diagnosis was obtained in all procedures; there was no postoperative morbility or morbidity. Conclusion: Preoperative computed tomography hook-wire localization is a suitable strategy for peripheral nodules ?1 cm in diameter.     

Latissimus dorsi transfer for primary treatment of irreparable rotator cuff tears

Transfer of the musculotendinous unit of the latissimus dorsi was performed in seven patients (5 men and 2 women, with a mean age of 57 years) with irreparable rotator cuff tear who had had no previous surgery for cuff repair. Preoperatively, the mean active shoulder motion was 86° in flexion, 74° in abduction and 22° in external rotation. One patient had a positive lift-off test. The average preoperative Constant and Murley score was 44%. Diagnosis of irreparability of the cuff leasion was made preoperatively only in one case. In the remaining patients, the preoperative data only led to suspect that the tear was irreparable. At surgery, all patients had an irreparable tear of the superoinferior portion of the cuff and one patient also had a tear of the subscapularis tendon. In all cases the latissimus dorsi tendon was inserted to the greater tuberosity and, in four cases, to the subscapularis tendon; in three patients it was sutured to the bicipital tendon. Postoperatively all patients had relief of shoulder pain. The mean improvement in active flexion, abduction and external rotation was, respectively, 39°, 29° and 10°: At the latest follow-up, the average Constant and Murley score was 64%. The results of surgery were rated as excellent in three cases, good in two, fair in one and poor in one. All patients but one returned to preoperative work. Transfer of the latissimus dorsi muscle is an effective procedure for patients in middle or early elderly age who have an irreparable tear of the supraspinatus and infraspinatus tendons. Received: 18 December 2001/Accepted: 4 January 2002     

Role of non-polio enterovirus infection in pediatric hemolytic uremic syndrome

Verocytotoxin-producing Escherichia coli(VTEC) infections cause most cases of hemolytic uremic syndrome (HUS); 10-30% of patients, however, are negative for VTEC infection. The etiology of HUS in VTEC-negative cases remains poorly understood. Before the association between VTEC infection and HUS was recognized, sporadic cases of HUS with enterovirus infection were reported in the literature. Since May 1988, most cases of HUS in Italy have been reported to the Italian surveillance system, and in 73% of these, evidence of VTEC infection was demonstrated. The aim of this study was to determine whether the frequency of enteroviral infections was different in the acute phase of VTEC-positive and VTEC-negative HUS. Eighty-nine patients were investigated for enteroviral infection, of whom 58 were VTEC positive and 31 VTEC negative. Two serum samples from each patient were examined for seroconversion to enterovirus (coxsackie, echovirus, and picornavirus) by a complement fixation test. Serological evidence of acute infection with non-polio enterovirus was found in 33 patients (37%) [20/58 (34.5%) VTEC positive and 13/31 (41.9%) VTEC negative]. There was no statistically significant difference between the two groups. These results demonstrate that there are no significant differences for enteroviral infection in VTEC-positive and VTEC-negative patients and, therefore, enteroviral infections should not be considered a cause of HUS in VTEC-negative children.     

Intravascular hemolysis in patients with new-generation prosthetic heart valves: a prospective study

OBJECTIVE: A prospective clinical study was designed to assess the frequency and severity of intravascular hemolysis in patients with new-generation, normally functioning prosthetic heart valves. METHODS: Hemolysis was evaluated in 172 patients with a mechanical prosthesis (53 CarboMedics and 119 Sorin Bicarbon) and in 106 patients with a bioprosthesis (15 St Jude Medical Toronto, 19 Baxter Perimount, and 72 Medtronic Mosaic) in the aortic position, mitral position, or both. Aortic valve replacement was performed in 206 patients, mitral valve replacement in 59 patients, and double valve replacement in 13 patients. The presence of hemolysis was assessed on the basis of the level of serum lactic dehydrogenase and serum haptoglobin and the presence and amount of reticulocytes and schistocytes in the peripheral blood. Severity of intravascular hemolysis was estimated on the basis of serum lactic dehydrogenase. Clinical, echocardiographic, and hematologic evaluations were performed 1, 6, and 12 months after discharge. RESULTS: None of the 278 patients experienced decompensated anemia, whereas at 12 months, mild subclinical hemolysis was identified in 49 patients, 44 (26%) with a mechanical prosthesis and 5 (5%) with a bioprosthesis (P <.001). At multivariate analysis, independent predictors of the presence of subclinical hemolysis were mitral valve replacement (P <.001), use of a mechanical prosthesis (P =.002), and double valve replacement (P =.02). Frequency of hemolysis in patients with stented aortic bioprostheses was 3%, whereas it was absent in those with stentless valves. Among mechanical valve recipients, double versus single valve replacement (P =.04) and mitral versus aortic valve replacement (P =.05) were correlated with the presence of hemolysis; double valve recipients also showed a more severe degree of hemolysis (P =.03). In patients with a Sorin Bicarbon prosthesis, hemolysis was less frequent (22% vs 34%, P =.09) and severe (P <.001) than in those with a CarboMedics prosthesis. CONCLUSIONS: In normally functioning prosthetic heart valves, subclinical hemolysis is a frequent finding. A low incidence of hemolysis is found in stented biologic prostheses, and it is absent in stentless aortic valves. Modifications of valve design may contribute to minimize the occurrence of hemolysis in mechanical prostheses.     

Temporary vena cava filters in the prevention of pulmonary embolism during total hip arthroplasty

Thromboembolism constitutes one of the most dangerous complications during the immediate postoperative period of prosthetic surgery. Pharmacological prophylaxis and mechanical vascular compression are not always sufficient to protect from this surgical complication. In patients at greatest risk for thromboembolism, often with a positive history for pulmonary embolism, temporary vena cava filters may be used to reduce the incidence of vascular and pulmonary complications. However useful, these filters cannot be routinely used in orthopedic surgery. We present our results with the use of Filcard RFO2 vena cava filters in an open, randomized study of 30 patients. Received: 5 November 2001/Accepted: 30 November 2001     

The use of touch preparation for the evaluation of sentinel lymph nodes in breast cancer

Background

This study was undertaken to evaluate the accuracy of touch preparation (touch prep) in the evaluation of sentinel lymph nodes (SLNs).

Methods

We performed a retrospective review of 402 breast cancer patients who underwent SLN biopsy.

Results

A SLN was identified in 381 patients. Of 61 patients with a true positive result, 59 underwent axillary node dissection, and in 22 the SLN was the only node with metastases. Thirty-six (9.44%) had at least 1 false negative result. Twenty-five with a false negative results were due to macrometastases, with 17 (2.4%) false negatives occurring in patients with invasive ductal and 6 (5.5%) in those with invasive lobular histology, P = .04. Touch prep had an overall sensitivity of 62.89% and specificity of 98.94%.

Conclusions

Touch prep for the evaluation of SLNs in breast cancer compares favorably to reported results for frozen section. False negative findings are more likely with micrometastases and invasive lobular histology.     

Microleakage of glass ionomer formulations after erbium:yttrium-aluminium-garnet laser preparation

The aim of this study was to investigate the microleakage in class V cavities restored with four conventionally setting glass ionomers (CGIs) and one resin-modified glass ionomer (RMGI) following erbium:yttrium–aluminium–garnet (Er:YAG) laser or conventional preparation. Four hundred class V cavities were assigned to four groups: A and B were prepared by an Er:YAG laser; C and D were conventionally prepared. In groups B and D, the surface was additionally conditioned with Ketac conditioner. Each group was divided into five subgroups according to the glass ionomer cement (GIC) used: groups 1 (Ketac Fil), 2 (Ketac Molar), 3 (Ionofil Molar), 4 (Ionofil Molar Quick) and 5 (Photac Fil Quick). After thermocycling, a 2% methylene blue solution was used as dye. Scanning electron microscope (SEM) photographs were taken to show the conditioner’s effect. Complete marginal sealing could not be reached. PhotacFil showed less microleakage than the conventionally setting glass ionomer cements (CGICs) investigated. Conditioning laser-prepared cavities did not negatively influence microleakage results except for Ionofil Molar Quick.     

Acute abdomen in renal transplant recipients. Epidemiology and treatment in not referral transplantation centers

The incidence of gastrointestinal complications in renal transplant recipients is relatively high while about 10% is related to acute abdomen. Data concerning gastrointestinal (GI) complications were reported in literature mainly from referral center studies. A multicenter retrospectively survey was performed in Lazio, Italy, in order to evaluate the incidence of acute abdomen in renal transplant recipients observed to the emergency departments of not referral transplantation centers. Clinical and demographic findings regarding 14 patients who experienced acute abdomen between February 2005 and Dicember 2008 have been collected. The following data was investigated: etiology, diagnostic workup, duration of symptoms, elapsed time between admission and emergency operation if performed, morbility and mortality. The severity of disease at presentation was assessed by mean of the Acute Physiology and Chronic Health Evaluation score (APACHE II). Acute abdomen was due to pancreatitis in three patients (23.1%); to cholecystitis in three (23.1%); to acute diverticolitis with colon perforation in two patients (15.4%); to acute appendicitis in two (15.4%) and to intestinal obstruction in 2 patients (15.4%). Small bowel perforation was observed in two patients (15.4%) which one case, upon pathological examination, showed malignant lymphoma. The mean APACHE II score was 14.0 ± 5.9. Ten patients (71.4%) were submitted to surgery. Overall mortality and morbidity were 35% and 42% respectively. Statistical analysis showed admission APACHE II score (p<0.01), duration of symptoms (p<0.05), and total time elapsed between the onset of symptoms and treatment (p<0.04) as factors significantly related to mortality.