Temperature rise during reamed tibial nailing

The current study determined the temperature rise during reamed tibial intramedullary nailing in vivo. Eighteen adult patients were studied. The tibial medullary canal diameter ranged from 8 to 11 mm and was reamed to at least 1.5 mm above the required nail diameter with AO reamers. Reaming of the medullary cavity ranged from 9 to 12 mm before nail insertion. Intraoperative monitoring of the heat produced during reaming of the medullary cavity was done by inserting two platinum resistance thermometer probes into the cortical bone at the short isthmic segment of the tibial shaft. The probes were connected to a data logger, and temperature readings were taken every 5 seconds during each reaming procedure. The mean tibial temperature before initiation of reaming was 35.6 degrees C (standard deviation, +/- 0.5 degrees), and peak temperatures recorded were from 36.1 degrees C to 51.6 degrees C. A direct correlation was observed between temperature elevation and amount of reaming. With reaming above 10 mm, tibias with a canal diameter of 8 mm showed a statistically higher temperature rise compared with tibias with a canal diameter of 9, 10, or 11 mm. No patients had intraoperative or postoperative complications related to skin or bone thermal necrosis, and bony healing progressed uneventfully. The small amount of reaming required to insert a nail into a normal 9-, 10-, or 11- mm tibial canal does not seem to produce a clinical problem. Reaming smaller canals (8 mm) to a larger size may induce a significant heating effect.

Fluoroscopy-based multiplanar image guidance for insertion of sacroiliac screws

A prospective controlled experimental study was done to assess the value of fluoroscopy-based, computer-assisted orthopaedic surgery for the insertion of sacroiliac screws and to compare this new technology with the conventional technique, using image intensification. In a simulated surgical setup, 140 cannulated screws were placed into the S1 and S2 vertebral bodies of 35 pelvic models. The screws were inserted under fluoroscopy-based image guidance or with the conventional technique. Different drills were tested with both techniques, including a 2.8-mm guide wire and a 5-mm solid drill. The 2.8-mm guide wire proved inaccurate with the computer-assisted image guidance system because of guide wire flexibility. Using the more rigid 5-mm drill, the results of computer-assisted image guidance were comparable with the image intensifier technique. The radiation exposure during screw insertion was reduced considerably when using the image guidance system. System-specific requirements warranted adjustment of surgical technique and instruments. The major advantages of this new technology are immediate intraoperative image acquisition and provision of surgical guidance in as much as four planes simultaneously. The results of this experimental study are encouraging and have led to initiation of a clinical trial.

Extending fixation beyond the working length of an intramedullary nail with a linked intramedullary and extramedullary fixation in complex femoral fractures; a brief series

We report the use of a fixed-angle side-plate device linked to an intramedullary nail in the femur with the interlocking screws applied through the plate. The 95 degrees device extends the effective length of the nail and increases the stability of the fixation. This technique is one of various adaptations that can be recommended to stabilise a complex combination of femoral fractures. This is a report of four such patients.

TNF alpha is required for hypoxia-mediated right ventricular hypertrophy

Hypoxia has been shown to activate the pleiotropic cytokine TNFalpha in the lung. TNFalpha in turn, is known to induce pulmonary vasoconstriction. Additional effects of this cytokine in hypoxia mediated cardiopulmonary remodeling are poorly understood. To further evaluate the role of TNFalpha in chronic hypoxia we exposed TNFalpha null (TNFalpha-/-) and wild-type mice to three weeks of hypobaric hypoxia (10% O2). Equivalent erythocytosis (Hematocrit increased by > 40%) developed in both genetic backgrounds. In contrast, right ventricular systolic pressure increased in response to three weeks of hypoxia in the wild-type mice (> or = 75%), yet was unaltered in the TNFalpha-/- mice. Concomitantly right ventricular hypertrophy was attenuated in the TNFalpha-/- mice (35 +/- 5% increase) when compared to wild-type mice (124 +/- 6% increase p < 0.001, n > or = 20). Interestingly in both strains the lung wet weights increased to a similar degree in response to hypoxia. In conclusion, our data demonstrate that TNFalpha is an integral autocoid in chronic hypoxia mediated right ventricular hypertrophy. Moreover, additional components of cardiopulmonary remodeling may be regulated by TNFalpha signaling as suggested by the negligible right ventricular systolic pressure response to hypoxia in the absence of TNFalpha.

Static friction properties between human palmar skin and five grabrail materials

The purpose of this study was to investigate the static friction properties between human palmar skin and five grabrail materials (chrome, stainless steel, power-coated steel, textured aluminium and knurled steel) for dry, wet and soapy hands. Thirty subjects (15 female, 15 male) participated in this study, their ages ranging from 19 to 45 years with a mean age of 28 years. The normal force, friction force, and coefficient of static friction were determined by measuring three-dimensional forces while slipping the palm of the hand over the surface of a grabrail. A repeated measures ANOVA indicated that gender, age, hand size and trial effect had no significant influence (p>0.05) on these results. The coefficient of friction (p<0.001) and friction force (p<0.001) were significantly lower when the hand was soapy than when it was dry or wet. The normal force applied when the hand was soapy was significantly greater (p<0.001) than when it was dry or wet. No significant difference was found between dry and wet hands. The two textured materials displayed superior friction properties when the hand was soapy, while the smooth materials performed best when the hand was dry.

Plasma membrane resident 'fusion complexes' mediate reconstituted exocytosis

Calcium-triggered exocytosis is thought to be mediated by membrane-associated protein complexes. In sea urchin eggs, high concentrations of calcium activate multiple 'fusion complexes' per cortical vesicle-plasma membrane docking site. Some of these fusion complexes are known to reside in the vesicle membrane. It is not known if fusion complexes also reside in the plasma membrane, or if plasma membrane-resident fusion complexes require cognate partners in the vesicle membrane. Using reconstitution, we show that N-ethylmaleimide treatment of either vesicles or plasma membrane fragments prior to reconstitution does not completely inhibit exocytosis. Treatment of both components did result in complete inhibition. Upon reconstitution, cortical vesicles and the early endosomes formed by compensatory endocytosis both contributed, on average, two fusion complexes per reconstituted docking site. The plasma membrane contributed, on average, two fusion complexes per docking site when assembled with cortical vesicles, but only one complex when reconstituted with endosomes. We conclude that there are at least two types of plasma membrane-resident fusion complexes that participate in reconstituted cortical vesicle-plasma membrane fusion. The activity of one of these fusion complexes is target-specific for cortical vesicles, while the second type also supports fusion with endosomes.

Inter-segment foot motion and ground reaction forces over the stance phase of walking

OBJECTIVE

To compare the magnitude and patterns of motion of the rearfoot segment relative to the leg, forefoot segment relative to the rearfoot, height change in the medial longitudinal arch and ground reaction forces of normal adult males during the stance phase of walking.

BACKGROUND

Knowledge of normal motion of the rearfoot and forefoot segments and of the arch during stance phase is important in clinical management.

METHODS

Motion data were obtained from surface markers, and force data from a force plate, from the right limb of participants while walking at a self-selected pace.

RESULTS

Stance phase range of motion across sagittal, frontal and transverse planes was 12 degrees, 4 degrees and 10 degrees for the forefoot, compared to 22 degrees, 8 degrees and 10 degrees for the rearfoot. Most motion occurred at the beginning and end of stance phase when support was via only the rearfoot or forefoot, and when forces were maximal. Arch height decreased from heel contact and increased after heel rise to its maximum at toe-off.

CONCLUSIONS

The extent of forefoot segment motion confirms the significance of midfoot joints to normal foot function. Between foot flat and heel rise, the forefoot pattern of motion is indicative of foot stability. Typical foot motion does not obey descriptions of triplanar motion such as 'pronation' and 'supination'.

RELEVANCE

Typical stance phase foot motion has been described according to a forefoot:rearfoot model and rearfoot:leg model of motion, together with profiles of medial longitudinal arch height and ground reaction forces. This information can be applied in the management of foot dysfunction and should stimulate research into midfoot motion and overall control of the foot.

Removal of the retained fragment of broken solid nails by the intra-medullary route

The development of solid nails has not eliminated the risk of occasional nail failure. It has been suggested that subsequent intra-medullary removal of solid nail fragment may be virtually impossible and thus major surgery is required for their revision. We report two cases of hardware failure of a solid intra-medullary nail (Synthes solid femoral and tibial nail) and describe their successful intra-medullary removal using the Synthes extraction kit.

Comparison of Roche MONITOR and Organon Teknika NucliSens assays to quantify human immunodeficiency virus type 1 RNA in cerebrospinal fluid

We compared Roche MONITOR and Organon Teknika NucliSens assays for human immunodeficiency virus type 1 (HIV-1) RNA in cerebrospinal fluid (CSF). Results of 282 assays were highly correlated (r = 0.826), with MONITOR values being 0.29 +/- 0.4 log(10) copies/ml (mean +/- standard deviation) values. Both assays can reliably quantify HIV-1 RNA in CSF.

Bilateral, simultaneous, spontaneous rupture of quadriceps tendons without trauma in an obese patient: a case report

This is a single case report of bilateral, simultaneous, spontaneous rupture of the quadriceps tendon caused by obesity without trauma. The patient was a 52-year-old, 350-pound, morbidly obese man with a sedentary life style whose quadriceps tendons ruptured while he was descending a staircase. He presented with a large deficit superior to the patella and an inability to straighten his knees. After surgery, his knees were immobilized in extension for 6 weeks, followed by gradual weight bearing and gait training with braces. He was weaned off the braces as he increased the range of motion and strength in his knees. The rehabilitation process was protracted, and he returned to full-time work 6 months postinjury. Physiatrists should be familiar with the diagnosis, treatment, and rehabilitation of this rare condition.

Extrinsic muscle activity, foot motion and ankle joint moments during the stance phase of walking

This study examined stance phase foot kinematics, kinetics and electromyographic (EMG) activity of extrinsic muscles of 18 healthy males. Three-dimensional kinematic and kinetic data were obtained via video analysis of surface markers and a force plate. Ankle joint moments are described about orthogonal axes in a segmental coordinate system. Kinematic data comprise rearfoot and forefoot motion, described about axes of a joint coordinate system, and medial longitudinal arch height. Surface EMG was obtained for tibialis anterior, soleus, gastocnemius medialis and lateralis, peroneus longus and peroneus brevis and extensor digitorum longus. It was concluded that the demands on the controlling muscles are greatest prior to foot flat and after heel rise. Tibialis anterior restrained rearfoot plantarflexion from heel contact to 10% stance, and eversion between 10% stance and footflat. Activity in peroneus longus was consistent with its role in causing eversion after heel contact, then as a stabiliser of the forefoot after heel rise. Activity in peroneus brevis suggested a role in restraining lateral rotation of the leg over the foot, late in stance.

Induction of immune hyporesponsiveness after portal vein immunization with ovalbumin

BACKGROUND

Previous work has demonstrated prolonged allograft survival after donor-specific portal vein immunization before the transplantation. The purpose of this study was to examine the potential mechanism of portal vein-induced hyporesponsiveness after portal vein immunization with the soluble protein ovalbumin.

METHODS

Balb/c mice were immunized with a portal vein injection of ovalbumin. After the immunization, in vivo delayed-type hypersensitivity response and in vitro proliferative response of ovalbumin-specific T cells were assessed to determine host immune response. Type 1 (IL-2, IL-12, IFN-gamma) and type 2 (IL-4, TGF-beta) regulatory cytokines were assessed by semiquantitative reverse transcriptase polymerase chain reaction. Sera anti-ovalbumin IgG, IgG1, and IgG2a were measured by enzyme-linked immunosorbent assay, and the antigen-presenting ability of liver nonparenchymal cells (NPCs) was assessed by T-cell proliferation to ovalbumin in vitro.

RESULTS

There was significant inhibition of ovalbumin-specific delayed-type hypersensitivity and T-cell proliferation in portal vein-immunized mice compared with intraperitoneal-immunized or control mice. Reverse transcriptase polymerase chain reaction analysis results showed that lymphocytes from portal vein-immunized mice exhibited decreased type 1 and increased type 2 cytokine messenger RNA expression compared with intraperitoneal-immunized or control animals. The type 2 cytokine response of lymphocytes from ovalbumin portal vein-immunized mice correlated with increased sera ovalbumin-IgG1 and decreased IgG2a. The results of an antigen-presenting assay revealed that liver NPCs were deficient antigen-presenting cells compared with adherent cells from heart or spleen.

CONCLUSIONS

Processing of ovalbumin by hepatic NPCs results in hyporesponsiveness to ovalbumin by an impaired type 1 cytokine response and a preferential shift toward a type 2 cytokine response, possibly because of defective antigen presentation by hepatic NPCs. Intrahepatic processing of antigen may play an important role in the development of strategies to reduce host immunoreactivity against transplanted allografts.

The ocular impression: A review of the literature and presentation of an alternate technique

Improved fit is one advantage of a custom ocular prosthesis. Numerous methods exist to gain intimate tissue adaptation. This article reviews the literature concerning such methods and presents an improved technique for fabrication of a custom ocular impression tray.

Guanine nucleotide transport by atractyloside-sensitive and -insensitive carriers in isolated heart mitochondria

In previous work (McKee EE, Bentley AT, Smith RM Jr, and Ciaccio CE, Biochem Biophys Res Commun 257: 466-472, 1999), the transport of guanine nucleotides into the matrix of intact isolated heart mitochondria was demonstrated. In this study, the time course and mechanisms of guanine nucleotide transport are characterized. Two distinct mechanisms of transport were found to be capable of moving guanine nucleotides across the inner membrane. The first carrier was saturable, displayed temperature dependence, preferred GDP to GTP, and did not transport GMP or IMP. When incubated in the absence of exogenous ATP, this carrier had a V(max) of 946 +/- 53 pmol. mg(-1). min(-1) with a K(m) of 2.9 +/- 0.3 mM for GDP. However, transport of GTP and GDP on this carrier was completely inhibited by physiological concentrations of ATP, suggesting that this carrier was not involved with guanine nucleotide transport in vivo. Because transport on this carrier was also inhibited by atractyloside, this carrier was consistent with the well-characterized ATP/ADP translocase. The second mechanism of guanine nucleotide uptake was insensitive to atractyloside, displayed temperature dependence, and was capable of transporting GMP, GDP, and GTP at approximately equal rates but did not transport IMP, guanine, or guanosine. GTP transport via this mechanism was slow, with a V(max) of 48.7 +/- 1.4 pmol. mg(-1). min(-1) and a K(m) = 4.4 +/- 0.4 mM. However, because the requirement for guanine nucleotide transport is low in nondividing tissues such as the heart, this transport process is nevertheless sufficient to account for the matrix uptake of guanine nucleotides and may represent the physiological mechanism of transport.

Adaptation of a relocatable head frame for stereotactic radiotherapy

An important role of the maxillofacial prosthodontist is to support the radiotherapist in the administration of therapy. For example, a device can be made that properly and repeatedly positions the patient for each radiation treatment. This article describes a procedure for adapting a relocatable head frame to be used during stereotactic radiotherapy, a treatment modality for malignant intracranial tumors.

Isolated cervical recurrence of squamous cell carcinoma in the previously treated neck

PURPOSE

Our study goal was to identify clinical factors associated with, and that might predict, treatment outcome for patients with an isolated cervical recurrence of squamous cell carcinoma in the previously treated neck (ICR-PTN).

MATERIALS AND METHODS

We reviewed all patients with noncutaneous head and neck squamous cell carcinoma treated at our tertiary care center between 1987 and 1997, and identified 17 patients (2%) who later developed an isolated recurrence in a previously treated neck. These patients made up our study group, and their charts were thoroughly reviewed. Outcome of salvage therapy (surgery, radiation, or combined therapy) for these patients was compared with pooled clinicopathologic data using the Fisher exact test (one tail).

RESULTS

Fifteen such ICR-PTN patients consented to salvage therapy. Six patients were without disease at last follow-up, and 3 were successfully palliated. A statistically significant association between the side of ICR-PTN relative to the primary tumor and outcome of salvage therapy (P =.026) was noted, with ipsilateral neck recurrence being a favorable prognostic factor. Trends that did not meet the standard for statistical significance were observed between a better outcome of salvage therapy and the following parameters: age of less than 60, nonsurgical initial treatment of the neck, and lack of a history of a recurrence before they developed the ICR-PTN.

CONCLUSIONS

The current study showed that only the side of the ICR-PTN relative to the primary site is associated with outcome of salvage therapy. Based on our findings and a review of the literature, we have developed a summary of factors that might predict which patients with an ICR-PTN are most likely to benefit from aggressive salvage therapy.

Multiple ectopic parathyroid glands

Parathyroid surgery to correct primary hyperparathyroidism is successful in 80 to 97 per cent of initial explorations. Failures are often linked to inability to locate ectopic parathyroid glands. Although ectopic parathyroid glands are relatively common (15%) multiple ectopic glands are rarely reported. We describe a case of multiple ectopic parathyroid glands and the intraoperative approach to their localization and review the anatomy and embryology of ectopic parathyroid glands. A 39-year-old woman presented with fatigue, lethargy, and depression. On biochemical evaluation she was noted to be hypercalcemic and hyperparathyroid. Preoperative parathyroid localization failed to identify abnormal parathyroid glands. At exploration three of four parathyroid glands, including an adenoma, were located in ectopic positions by a meticulous and systematic dissection. A careful exploration coupled with a thorough knowledge of parathyroid anatomy and embryology will produce successful surgical correction of primary hyperparathyroidism in greater than 95 per cent of patients even in the few patients with multiple ectopic parathyroid glands.

Simultaneous bilateral femoral fractures: systemic complications in 14 cases

We have retrospectively reviewed 14 patients with bilateral femoral shaft fractures who attended our institution between January 1993 and March 1999. The mean age of the patients was 38 years (19-75) and the median injury severity score (ISS) was 16 (interquartile range 10-20). Thirteen patients were treated with intramedullary nailing and 1 with plating and nailing within 24 h of admission to hospital. The mean resuscitation requirements were 10.6 (6-16) litres of colloid and crystalloid and 8.6 (4-30) units of blood. The mean intensive care unit/high dependency unit (ICU/HDU) stay was 4 days (1-14) and the mean hospital stay was 36.3 days (3-210). There were 6 cases of adult respiratory distress syndrome (ARDS), 1 compartment syndrome, 1 case of osteomyelitis, 1 above-knee amputation and 2 deaths (14.2%). The mean time to union was 24.5 weeks (12-37). Comparison to patients with unilateral injuries revealed a higher ISS, resuscitation requirements, ARDS, hospital stay and mortality.