Perioperative bladder management after primary total hip arthroplasty.

A retrospective review of 95 consecutive primary total hip arthroplasty patients was performed to assess the clinical outcome of two postoperative bladder management protocols. The first 49 patients (group 1) were treated with a pro re nata straight catheterization protocol. The next 46 patients (group 2) were treated with an indwelling catheterization protocol. There were no differences between the groups with respect to sex or age. The patients in group 2 had significantly lower incidences of urinary retention (P < .0005) and bladder distention (P < .0005) than those in group 1. Preoperative systemic diseases and urologic symptoms did not correlate with the occurrence of postoperative urinary retention or bladder distention. There were no infections in group 1. In group 2, one patient (2%) had bacteriuria and one patient (2%) had a urinary tract infection (P > .1). This trend of increased contamination in the catheterization group may be related to a mean catheterization duration of 72 hours.

Total hip arthroplasty cemented femoral component distal stem centralizer. Effect on stem centralization and cement mantle.

The effectiveness, benefits, and potential risks of employing a total hip arthroplasty cemented femoral component distal centralizer were evaluated. First postoperative (6-week) radiographs of 100 primary hybrid total hip arthroplasties in consecutive groups of 50 patients without and 50 patients with a femoral stem distal centralizer were retrospectively reviewed. Femoral stems with a distal centralizer were more centralized within the femoral canal (center of stem tip to center of intramedullary canal: mean, 1.1 mm with a centralizer, 3.2 mm without; P<.0001) and more neutrally aligned (mean, 0.7 degrees valgus with a centralizer, 1.3 degrees valgus without; P < .01). Femoral stems with a distal centralizer were less likely to have a cement mantle with suboptimal thickness, that is, less than 2 mm at the medial distal femoral stem (3 of 50 stems with a centralizer, 22 of 50 stems without; chi-square, P<.0001). There were no complications, adverse effects on the cement mantle, radiographic evidence of loosening, or implant failures associated with the use of a distal centralizer, with a minimum follow-up period of 2 years.

Postoperative surveillance for deep venous thrombosis with duplex ultrasonography after total knee arthroplasty.

Duplex ultrasonography of the lower extremity was used for routine non-invasive screening for asymptomatic proximal and distal deep venous thrombosis, for monitoring of potential propagation of deep venous thrombosis from distal to proximal, and for confirmation of the resolution of proximal deep venous thrombosis after treatment. In the first part of the study, to substantiate the accuracy of duplex ultrasonography, 130 lower limbs (seventy-nine patients) were studied with that modality as well as with venography after a total hip or total knee arthroplasty. Compared with venography, duplex ultrasonography demonstrated 100 per cent sensitivity, specificity, and accuracy for the detection of proximal deep venous thrombosis and 88 per cent sensitivity, 98 per cent specificity, and 98 per cent accuracy for the detection of distal deep venous thrombosis. In the second part of the study, 100 patients who had had a total knee arthroplasty and had been managed with pneumatic stockings and aspirin for prophylaxis against deep venous thrombosis had screening of both lower extremities with duplex ultrasonography on the fourth postoperative day. Duplex ultrasonography demonstrated proximal deep venous thrombosis in seven patients and distal deep venous thrombosis in twenty-two patients; all twenty-nine patients were asymptomatic. The patients who had distal deep venous thrombosis had surveillance with serial duplex ultrasonography on the seventh and fourteenth postoperative days; five of these patients were found to have had propagation of the thrombosis to the proximal deep veins.(ABSTRACT TRUNCATED AT 250 WORDS)

Routine postoperative duplex ultrasonography screening and monitoring for the detection of deep vein thrombosis. A survey of 110 total hip arthroplasties.

The use of duplex ultrasonography for routine noninvasive screening, monitoring, and management of deep venous thrombosis after total hip arthroplasty was evaluated. The reliability of duplex ultrasonography for detection of deep vein thrombosis was confirmed in an initial cohort of 51 total hip arthroplasty patients (102 lower extremities), demonstrating 91% sensitivity, 98% specificity, and 97% accuracy when compared with venography. A second cohort of 110 total hip arthroplasty patients using pneumatic compression stockings and aspirin as deep vein thrombosis prophylaxis underwent screening duplex ultrasonography of both lower extremities on postoperative Day 4. Duplex ultrasonography screening showed 10 (9.1%) patients with proximal deep vein thrombosis and 10 (9.1%) with distal deep vein thrombosis, all of whom were asymptomatic. The 10 patients with proximal deep vein thrombosis on duplex ultrasonography were prescribed therapeutic anticoagulation. Duplex ultrasonography subsequently confirmed resolution of proximal deep vein thrombosis in these patients before discontinuation of anticoagulation; none developed symptomatic pulmonary embolism through 12-month clinical followup. The 10 patients with distal deep vein thrombosis diagnosed by duplex ultrasonography were not treated with anticoagulation, but were monitored by serial duplex ultrasonography through postoperative Day 14 for propagation of distal to proximal deep vein thrombosis; none manifested symptomatic deep vein thrombosis or pulmonary embolism through 12-month clinical followup. The 90 patients with negative duplex ultrasonography results were followed clinically; 3 developed late symptomatic proximal deep vein thrombosis (1 of these later manifested pulmonary embolism). Therefore, duplex ultrasonography was used after total hip arthroplasty for the following: (1) to screen routinely in the hospital for asymptomatic proximal and distal deep vein thrombosis; (2) to monitor for potential propagation of distal to proximal deep vein thrombosis; (3) to minimize exposure to therapeutic anticoagulation by confirming the absence of proximal deep vein thrombosis in 97 of 110 patients; and (4) to demonstrate the effectiveness of mechanical and systemic deep vein thrombosis management by confirming the absence or resolution of deep vein thrombosis in all 110 patients.

The entire rotator cuff contributes to elevation of the arm.

The function of the infraspinatus, teres minor, and subscapularis during elevation of the arm remains poorly defined. These muscles may generate moments that contribute to abduction of the arm, although they frequently are classified as humeral depressors. The purposes of this study were to measure the contributions to abduction made by the more inferiorly positioned rotator cuff muscles relative to the contributions of the supraspinatus and to determine the range of motion at which the muscles are most effective. Five fresh cadaveric shoulder girdles were mounted in an apparatus designed to simulate contraction of the deltoid and rotator cuff while maintaining the normal relationship between glenohumeral and scapulothoracic motions. The deltoid force required for elevation was measured without simulated contraction of the rotator cuff and with simulated contraction of the entire rotator cuff, of the supraspinatus only, and of the infraspinatus-teres minor and subscapularis only. A significant reduction in deltoid force when other muscle activity was added indicated that the additions contributed significantly to abduction. The deltoid force required with concurrent contraction of the entire rotator cuff averaged 41% less than with the deltoid alone but was not significantly different than with the deltoid and supraspinatus or with the deltoid, infraspinatus-teres minor, and subscapularis. Concurrent application of forces to the supraspinatus or the infraspinatus-teres minor and subscapularis significantly reduced the required deltoid force over the range of motion studied by an average of 28 and 36%, respectively. The contributions of the rotator cuff muscles to abduction of the arm were greatest at low abduction angles (30 and 60 degrees) and were insignificant by 120 degrees. The infraspinatus-teres minor and subscapularis contribute significantly to abduction: their contribution was equal to that of the supraspinatus and, like the supraspinatus, they are most effective during the first 90 degrees of abduction.

Anatomic and biomechanical assessment of transarticular screw fixation for atlantoaxial instability.

The purpose of this study is to elucidate anatomically the atlantoaxial transarticular screw fixation described by Magerl in 1979 and compare it biomechanically with Gallie wiring. Five human C1-C2 specimens were tested in flexion/extension and rotation intact, then after wiring and screw fixation. Mean screw length was 39 mm, 25 mm in the C2 lamina and 14 mm in the lateral mass. Angular displacement of screwed specimens was significantly less than control or wired groups. Stiffness at 0-0.5 Nm loads was significantly greater for screwed specimens than for wired or controls (101 +/- 49 Nm, 10.3 +/- 9.2 Nm, and 1.96 +/- 0.18 Nm, respectively). All specimens withstood 5 Nm in flexion and extension without failure. Screw fixation provides stability comparable to Gallie wiring and is stiffer at low-range forces and rotational angles.

Open fractures of the pelvis. Review of 43 cases.

We reviewed 43 patients treated from 1984 to 1988 for open fractures of the pelvis. There were four Gustilo type I wounds, seven type II and 32 type III; 22 fractures were stable and 21 unstable. The overall mortality was 30%; the average Injury Severity Score was 30, being 26 in the survivors and 40 in the fetal cases. We analysed the influence of a number of factors on the mortality rate. The most important were the ISS and the age in years, while the presence of a type III wound and instability of the fracture also had an influence. We describe two simple methods of assessment of the prognosis in individual cases, based on these factors.

Biomechanics of cervical spine internal fixation.

Recent advances in the area of cervical spine internal fixation have resulted in important additions to the armamentarium of the spine surgery. However, a sophisticated knowledge of the biomechanics of these devices is important. This article discusses the biomechanics of odontoid screws, anterior cervical plates, posterior cervical plates, and posterior C1-C2 screw arthrodesis. It is hoped that this information will aid in implant selection.

Interrenal function in larval Ambystoma tigrinum. I. Responses to alterations in external electrolyte concentrations.

Larval Ambystoma tigrinum were acclimated to distilled water, 150 mM NaCl, or 100 mM KCl to alter electrolyte balance. The effects on electrolyte balance and circulating interrenal steroids were observed by analysis of plasma and urine samples. Steroid titers were measured by radioimmunoassay. Acclimation to distilled water decreased plasma and urinary [Na+] and elevated circulating aldosterone (sixfold) and corticosterone (45%) but did not affect cortisol. Larvae acclimated to 150 mM NaCl experienced increases in plasma and urinary [Na+]. In this group aldosterone titer was depressed (47%), corticosterone was elevated (100%), and cortisol was unchanged. Salamanders acclimated to 100 mM KCl increased plasma and urinary [K+] and shifted to net renal K+ secretion. This group elevated aldosterone (150%); however, corticosterone was not significantly affected. Reciprocity between the Na+-loaded and K+-loaded groups was observed. Acclimation to high potassium stimulated fractional renal Na+ reabsorption while Na+ loading stimulated fractional K+ reabsorption. These findings are consistent with aldosterone having opposite effects on renal Na+ and K+ transport, stimulating the reabsorption of the former and the net secretion of the latter.