Imaging of spindle cell lipoma.

AIM: To review the evaluation, diagnosis, and treatment of spindle cell lipoma (SCL) with emphasis on the location of these tumours and the spectrum of magnetic resonance imaging (MRI) and computed tomography (CT) appearances. MATERIALS AND METHODS: The MRI and CT findings of 27 histopathologically proven SCLs were evaluated retrospectively. Imaging features evaluated included margins, percentage visible fat, MRI signal characteristics, oedema, and contrast enhancement patterns. RESULTS: Patient ages ranged from 18 to 80 years with an average age of 56.5 years. Men were affected twice as frequently as women (M=18, F=9). SCLs ranged in size from 2 to 10 cm, with an average greatest dimension of 5.5 cm. Five lesions (19%) contained no visible fat on CT or MRI, and the leading differential diagnosis of high-grade soft-tissue sarcoma diagnosis was suggested by referring surgeons. Five lesions (19%) had <50% fatty areas, nine lesions (52%) demonstrated >50% but <90% fat at MRI or CT. Only three of 25 lesions (12%) had an appearance of a typical lipoma on unenhanced MRI sequences. All SCLs that were imaged with contrast medium (n = 18) demonstrated some degree of enhancement, with eight (44%) showing marked enhancement, four (22%) showing moderate, and six (33%) minimal enhancement. CONCLUSION: SCLs have considerably variable imaging appearances and may have minimal or no visible fat at MRI or CT. Imaging features may make it difficult to distinguish this benign tumour from a potentially higher-grade malignant tumour.

Survival after induction chemotherapy and surgical resection for high-grade soft tissue sarcoma. Is radiation necessary?

BACKGROUND: Induction chemotherapy can produce dramatic necrosis in sarcomas-raising the question of whether or not radiation is necessary. This study reviews the clinical outcome of a subset of patients with high-grade extremity soft tissue sarcomas (STS) who were treated with induction chemotherapy and surgical resection but without radiation. METHODS: Nonmetastatic, large, high-grade STS of the pelvis and extremities were treated with intra-arterial cisplatin, adriamycin, and, after 1995, ifosfamide. After induction, oncologic resection and histologic evaluation were performed. Good responders with good surgical margins were not treated with radiation. RESULTS: Thirty-three patients, with a median follow-up of 5 years, were included. Limb salvage rate was 94%. Median tumor necrosis was 95%. Four patients developed metastatic disease with three subsequent deaths. Two local recurrences occurred; both patients were salvaged with reresection and adjuvant external beam radiotherapy, although one died of metastatic disease 10 years later. Relapse-free and overall survival is 80% and 88% at 5 and 10 years by Kaplan-Meier analysis. CONCLUSIONS: Intensive induction chemotherapy can be extremely effective for high-grade STS, permitting limb-sparing surgery in lieu of amputation. Radiation may not be necessary if a good response to induction chemotherapy and negative wide margins are achieved. All patients with large, deep, high-grade STS of the extremities should be considered candidates for induction chemotherapy.

Reconstruction of hip stability after proximal and total femur resections.

Dislocation is the most common complication after proximal and total femur endoprosthetic reconstruction. The current study describes a surgical technique of acetabular preservation and reconstruction of the joint capsule and abductor mechanism that recreates joint stability and avoids dislocation. Between 1980 and 1996, 57 patients underwent proximal or total femur resection with endoprosthetic reconstruction. Forty-six patients had primary sarcoma of bone, nine had other bone tumors, and two had metabolic bone disease. The acetabulum was spared and not resurfaced in all patients. Bipolar hemiarthroplasty was performed in 49 patients, and fixed unipolar hemiarthroplasty was performed in eight. Soft tissue reconstruction included Dacron tape capsulorrhaphy over the prosthetic neck, reattachment of the abductor mechanism to the prosthesis, and extracortical bone fixation. The average followup period was 6.5 years (range, 2-18.2 years). Dislocation occurred in only one (1.7%) patient, and aseptic prosthetic loosening occurred in three (5.3%) patients. Four patients with primary bone sarcoma had local recurrence, of whom one required amputation of the limb. The limb salvage rate was 98%. Eighty-one percent of the patients had a good to excellent functional outcome. Acetabular preservation, capsulorrhaphy, and reconstruction of the abductor mechanism recreate hip stability and avoid dislocation after proximal and total femur endoprosthetic reconstruction.

The percutaneous needle biopsy is safe and recommended in the diagnosis of musculoskeletal masses.

BACKGROUND: The purpose of this study was to analyze the role of percutaneous core needle biopsy in the diagnosis of musculoskeletal sarcomas. METHODS: One hundred eighty-five biopsy procedures were performed on 161 musculoskeletal tissue masses suspected of being a sarcoma in 155 patients who underwent subsequent tumor resection. A percutaneous core needle biopsy was performed on all masses either in the clinic or under radiologic guidance. If an adequate diagnosis could not be made on the basis of this biopsy specimen, an open incisional biopsy was performed. RESULTS: One hundred seventy-three core needle biopsy procedures were performed: 90 without radiologic guidance, 55 computed tomography guided, and 28 fluoroscopically guided. Twelve open incisional biopsies were performed. Eighty-three sarcomas, 67 benign mesenchymal tumors, and 11 metastatic epithelial tumors were identified. Analysis of the data reveals that only 7.4% of the masses required open biopsy. In 88.2% of the masses, a single percutaneous biopsy procedure was adequate, and no additional biopsy was necessary. There was a 1.1% rate of complications; none caused a change in the patient's treatment plan. There was a 1.1% rate of major diagnostic errors, none of which ultimately impacted on the patient's outcome. There were no unnecessary amputations. Percutaneous needle biopsy showed a positive predictive value of 100%, a negative predictive value of 82%, a sensitivity of 81.8%, and a specificity of 100%. The accuracy of a single-needle biopsy procedure to identify benign versus malignant lesions, exact grade, and exact pathology was 92.4%, 88.6%, and 72.7%, respectively. CONCLUSIONS: The percutaneous needle biopsy was found to be extremely effective and safe for the diagnosis of musculoskeletal masses. This method allowed 88% of patients with suspected sarcomas to undergo a single-needle biopsy procedure before the initiation of definitive treatment. Patients undergoing percutaneous needle biopsy had lower rates of major diagnostic errors and complications than previously described for open biopsy. Open biopsy offered limited additional information when preceded by a needle biopsy, given that these tumors were difficult to identify even after final resection.

Extraspinal bone and soft-tissue tumors as a cause of sciatica. Clinical diagnosis and recommendations: analysis of 32 cases.

STUDY DESIGN: Between 1982 and 1997, the authors treated 32 patients with sciatica who subsequently were found to have a tumor along the extraspinal course of the sciatic nerve. SUMMARY OF BACKGROUND DATA: Extraspinal compression of the sciatic nerve by a tumor is a rare cause of sciatica. Signs and symptoms overlap those of the more common causes of sciatica (i.e., herniated disc and spinal stenosis). OBJECTIVE: To characterize the unique clinical presentation of these patients and to formulate guidelines that may lead to early diagnosis. METHODS: All pertinent clinical data and studies were reviewed retrospectively, and standard demographic data were collected for analysis. RESULTS: These patients typically sought treatment for an insidious onset of sciatic pain that was constant, progressive, and unresponsive to change in position or bed rest. The mean time to final diagnosis was 11.9 months (median, 6 months). Seventeen patients were able to locate their pain to a specific point along the extraspinal course of the sciatic pain, and a mass was noted in 13 patients. Eighteen of these tumors were in the pelvis, 10 in the thigh, and 4 in the popliteal fossa and calf. CONCLUSIONS: A high index of clinical suspicion is the key to early diagnosis of bone or soft-tissue tumors as a cause of sciatica; special attention should be given to pain pattern, physical examination of the entire course of the sciatic nerve, and selection of proper imaging studies. Routine anteroposterior plain radiography of the pelvis as part of the initial imaging screening process is recommended.

Cryosurgery in the treatment of giant cell tumor. A long-term followup study.

Between 1983 and 1993, 102 patients with giant cell tumor of bone were treated at three institutions. Sixteen patients (15.9%) presented with already having had local recurrence. All patients were treated with thorough curettage of the tumor, burr drilling of the tumor inner walls, and cryotherapy by direct pour technique using liquid nitrogen. The average followup was 6.5 years (range, 4-15 years). The rate of local recurrence in the 86 patients treated primarily with cryosurgery was 2.3% (two patients), and the overall recurrence rate was 7.9% (eight patients). Six of these patients were cured by cryosurgery and two underwent resection. Overall, 100 of 102 patients were cured with cryosurgery. Complications associated with cryosurgery included six (5.9%) pathologic fractures, three (2.9%) cases of partial skin necrosis, and two (1.9%) significant degenerative changes. Overall function was good to excellent in 94 patients (92.2%), moderate in seven patients (6.9%), and poor in one patient (0.9%). Cryosurgery has the advantages of joint preservation, excellent functional outcome, and low recurrence rate when compared with other joint preservation procedures. For these reasons, it is recommended as an adjuvant to curettage for most giant cell tumors of bone.

Assessing strength of preference for abortion method using 'willingness to pay': a useful research technique for measuring values.

Policy makers and practitioners need to differentiate between patient preferences which are strongly held, and those which are not. This study measured not only women's preferences for medical abortion versus surgical vacuum aspiration, but also the strength of these preferences, using a 'willingness to pay' (WTP) technique. Fifty women were recruited and interviewed prior to and following termination of early pregnancy. Due to the sensitivity of the situation, the WTP approach was administered by interview. Results revealed that 34 (64%) preferred to have the medical method. The amounts offered for each method were similar; however, a minority gave higher values for the medical method, thus for those women their strength of preference for that method was more intense. Validity of the technique was supported by the finding of a positive association with social class and the importance women attached to having choice. It is argued that WTP is an acceptable method for the elicitation of strength of treatment preferences. Its further use by nurses and midwives to assess health care preferences should be explored, particularly when considering aspects of care which are traditionally difficult to identify and measure.

Medical abortion or vacuum aspiration? Two year follow up of a patient preference trial.

OBJECTIVE: To describe and compare health outcomes two years after medical abortion or vacuum aspiration in women recruited into a patient preference trial during 1990 to 1991. DESIGN: Women recruited to the original, partially randomised study were contacted for assessment using a structured interview. SETTING: Grampian region of Scotland, UK. PARTICIPANTS: One hundred and forty women who had participated in a partially randomised study of first trimester abortion two years previously. INTERVENTION: Vacuum aspiration or medical abortion using mifepristone and gemeprost. MAIN OUTCOME MEASURES: Long-term general, reproductive and psychological health; acceptability of procedure; perceived value of choice of method of termination. RESULTS: There were no significant differences between women who had undergone medical abortion or vacuum aspiration two years previously in general, reproductive or psychological health. Almost all women placed a high value on the provision of choice of method of termination. There was a significant difference in perception of long term procedure acceptability among women who had been randomised to a method of termination. CONCLUSIONS: Women should have the opportunity to choose the method of termination. This opportunity will result in high levels of acceptability, particularly at gestations under 50 days of amenorrhoea.

PIP: In a comparative study conducted during 1990-91, 363 Scottish women with pregnancies of less than 64 days of gestation were given the option of selecting medical abortion with mifepristone/gemeprost or surgical vacuum aspiration abortion; those without a preference were randomly assigned to a method. There were no differences between groups in efficacy or medical complications at the 21-day postabortion follow-up. Medical abortion was associated with significantly more pain during the procedure, but not following hospital discharge, and its efficacy decreased with advancing gestation. At a median time interval of 26 months after the abortion, 140 women from the original cohort were reinterviewed to assess long-term acceptability. There were no significant differences between the medical and surgical abortion groups at long-term follow-up in their assessment of their current health status, the nature and incidence of subsequent morbidity requiring a doctor's care, consultations for psychiatric problems, or menstrual disorders. 9% of women who opted for surgical abortion and 11% who chose medical abortion indicated they would select a different method in the future. Vacuum aspiration remained significantly more acceptable than medical abortion among women who were randomly allocated to an abortion group. 97 women (69%) rated the opportunity to choose an abortion method as highly important, and 86-90% indicated a willingness to pay for the provision of such choice.

Intractable pelvic pain following Filshie clip application.

PIP: Presented is the case of a 37-year-old South Australian woman who experienced intractable pelvic pain following laparoscopic sterilization with Filshie clips. The pelvic anatomy was normal and one Filshie clip was applied to each Fallopian tube. The patient stated she had experienced right-sided lower abdominal pain that radiated down the anterior part of her right thigh since regaining consciousness after general anesthesia. The pain had failed to resolve seven days after the procedure and the patient was unable to perform even simple tasks. Analgesics provided only temporary, partial relief. There were no signs of infection or any other exacerbating condition. At diagnostic laparoscopy, instillation of bupivacaine around the clip provided transient relief, but the pain returned the next day at the same level of severity. After one month of intractable pain, laparoscopic bilateral salpingectomy was performed to remove the clips and the pain disappeared. Although back pain has been reported in up to 14% of women undergoing laparoscopic sterilization, this is the first published case of long-term abdominal pain associated with the Filshie clip.^ieng

The costs of treating miscarriage: a comparison of medical and surgical management.

OBJECTIVES: To estimate and compare the costs of surgical and medical treatment of miscarriage to the National Health Service. DESIGN: A patient-centred, partially randomised trial. SETTING: A teaching hospital in Scotland. PARTICIPANTS: Four hundred and thirty-seven women with a proven first trimester miscarriage. MAIN OUTCOME MEASURES: The cost per patient of surgical and medical management of miscarriage plus the extra cost per patient of introducing medical management of miscarriage under three different scenarios are calculated. RESULTS: The average cost of surgical treatment was Pounds 397 compared with Pounds 347 for medical treatment. Sensitivity analysis showed that the extra cost of introducing the medical management of miscarriage ranged from a cost saving of Pounds 71 per patient to an additional cost of Pounds 47 per patient. CONCLUSIONS: Our analysis showed that it may be possible to generate cost savings by introducing medical methods in the management of early miscarriage. However, the savings assume that costs associated with theatre use can be fully realised.

Delayed reduction of traumatic knee dislocation. A case report and literature review.

Knee dislocation after high energy trauma poses a major challenge to patients and treating physicians. The case presented documents the history and treatment of an unreduced posterior knee dislocation discovered 24 weeks after injury. Delayed surgical reduction was achieved, and satisfactory results were obtained with 22 months of followup of the patient. A detailed review of the literature found no comparable examples of longstanding traumatic dislocations of the knee but shed light on the probable cause for this unusual case. Close clinical followup, even after appropriate initial treatment of knee dislocations, is needed to eliminate similar occurrences.

3-Nitropropionic acid neurotoxicity is attenuated in copper/zinc superoxide dismutase transgenic mice.

The mitochondrial toxin 3-nitropropionic acid (3-NP) produces selective striatal lesions in both experimental animals and humans. The pathogenesis of the lesions involves secondary excitotoxicity that may then lead to free radical generation. To test this further we examined the effects of 3-NP in both transgenic (Tg) mice that carry the complete sequence for the human copper/zinc superoxide dismutase (SOD) gene as well as non-Tg littermate controls. The Tg-SOD mice showed a pronounced attenuation of Nissl-stained striatal lesions compared with non-Tg mice. Systemic administration of 3-NP resulted in production of hydroxyl free radicals as assessed by the conversion of salicylate to 2,3- and 2,5-dihydroxybenzoic acid. This production was attenuated significantly in Tg-SOD mice. In a similar way, 3-NP produced significant increases in 3-nitrotyrosine/tyrosine, a marker for peroxynitrite-mediated damage, which were significantly attenuated in Tg-SOD mice. These results support that oxygen free radicals and peroxynitrite play an important role in the pathogenesis of 3-NP neurotoxicity.

Basic fibroblast growth factor protects against excitotoxicity and chemical hypoxia in both neonatal and adult rats.

Basic fibroblast growth factor (bFGF) is a polypeptide growth factor that promotes neuronal survival. We recently found that systemic administration of bFGF protects against both excitotoxicity and hypoxia-ischemia in neonatal animals. In the present study, we examined whether systemically administered bFGF could prevent neuronal death induced by intrastriatal injection of N-methyl-D-aspartate (NMDA) or chemical hypoxia induced by intrastriatal injection of malonate in adult rats and 1-methyl-4-phenylpyridinium (MPP+) in neonatal rats. Systemic administration of bFGF (100 micrograms/kg) for three doses both before and after intrastriatal injection of either NMDA or malonate in adult rats produced a significant neuroprotective effect. In neonatal rats, bFGF produced dose-dependent significant neuroprotective effects against MPP+ neurotoxicity, with a maximal protection of approximately 50% seen with either a single dose of bFGF of 300 micrograms/kg or three doses of 100 micrograms/kg. These results show that systemic administration of bFGF is effective in preventing neuronal injury under circumstances in which the blood-brain barrier may be compromised, raising the possibility that this strategy could be effective in stroke.

Psychological responses following medical abortion (using mifepristone and gemeprost) and surgical vacuum aspiration. A patient-centered, partially randomised prospective study.

BACKGROUND: A substantial body of objective data now exists to support the consensus view that induced abortion results in a low incidence of psychiatric morbidity. However, these data do not include more recent advances in abortion technology. Medical abortion entails a participatory role on the part of the woman, who may perceive more pain or see products of conception. The physical and psychological events experienced by women undergoing this procedure may lead to differences in psychopathology. METHODS: 363 women undergoing legal induced abortion up to 63 days gestation were allocated by a prospective partially randomised design to undergo medical abortion (using mifepristone 600 mg followed 48 h later by gemeprost 1 mg vaginal pessary) or vacuum aspiration performed under general anesthesia. This study design allowed women with a preference for a particular method to undergo that method; women without preferences were allocated at random. Women completed sensitive and reliable psychometric instruments (the Hospital Anxiety and Depression Scale and a semantic differential rating scale designed to measure self-esteem) prior to abortion and 16 days later. RESULTS: There were no significant differences between women allocated at random to medical abortion or vacuum aspiration in post-abortal anxiety, depression or low self-esteem. Women with high levels of mood disturbance prior to abortion, who were smokers or who had medical complications following abortion were at highest risk of post-abortal mood disorder. CONCLUSIONS: Medical abortion is a psychologically safe as surgical vacuum aspiration. The quantitative findings of the study support the consensus view that abortion is associated with high incidence of psychological benefit, whichever method is used.

PIP: A prospective study of 363 abortion patients failed to provide evidence that women who receive a mifepristone/gemeprost medical abortion are at any greater risk of subsequent psychiatric morbidity than those who undergo the traditional vacuum aspiration procedure. Since women who undergo medical abortions are exposed to more pain, may see the products of conception, and generally play a more participatory role in the process, they were hypothesized to experience more psychological trauma than other abortion patients. The 168 women in the medical abortion subgroup received 600 mg of mifepristone followed 48 hours later by a vaginal pessary containing 1 mg of gemeprost. All subjects completed the Hospital Anxiety and Depression Scale and a self-esteem measure before and an average of 16 days after abortion. Overall, 165 women (45.5%) were significantly anxious and 67 (18,5%) were clinically depressed at baseline; after abortion, these rates had dropped to 37 (10.2%) and 9 (2.5%), respectively. Only 4 women who were non-anxious at baseline were anxious at follow up, while post-abortion depression developed in just 2 women. 190 women (55%) reported an improvement in self-esteem at follow up compared to baseline, 25 (7%) experienced no change, and 130 (38%) reported a decrease in self-esteem--a finding that is considered temporary and an integral part of the post-abortion grieving process. There was a significant correlation between anxiety and depression subscale scores before and after abortion and a significant negative correlation with self-esteem scores. There were no significant differences in any of these scores, however, between women who received medical versus vacuum aspiration procedures. Depression subscale scores at follow up were significantly related to postabortal medical complications, while anxiety scores after abortion were correlated with the number of physician consultations and the time required to resume normal activities. Baseline characteristics significantly associated with high anxiety and depression scores included cigarette smoking and a pre-existing mood disorder.

A comparison of medical abortion (using mifepristone and gemeprost) with surgical vacuum aspiration: efficacy and early medical sequelae.

A total of 363 women undergoing legal abortion at < 63 days of amenorrhoea were allocated by a patient-centered, partially randomized study design to undergo medical abortion (using mifepristone 600 mg followed 48 h later by gemeprost 1 mg vaginal pessary) or vacuum aspiration (performed under general anaesthesia). The aim of the study was to compare the efficacy and complications of the two procedures. Main outcome measures included efficacy rates, medical complications within 21 days of abortion and unplanned family doctor consultation rates within 8 weeks following abortion. Sequelae such as pain, vaginal bleeding and recovery time were assessed by the change in haemoglobin level, the time taken to return to work or normal activity and the analgesic use. Results were gestation-related; at 50 days of amenorrhoea there was little to choose between the two procedures. At 50-63 days of amenorrhoea medical abortion becomes more painful and less effective, whereas vacuum aspiration retains high tolerance and efficacy. Women who are unsure which method to use are likely to find vacuum aspiration more acceptable at longer gestations.

PIP: In Aberdeen, Scotland, researchers compared the efficacy rate of medical abortion with that of vacuum aspiration and examined their complications and the nature and incidence of short-term sequelae. All 363 pregnant women had amenorrhea for less than 63 days. The medical abortion procedure consisted of administration of 600 mg mifepristone followed by 1 mg gemeprost (vaginal pessary) 48 hours later. Women who underwent medical abortion at less than 50 days gestation were less likely to experience pain than those who underwent medical abortion between 50 and 63 days gestation (mean pain related index [PRI] scores, 20.5 vs. 25.5, p = 0.04 and analgesia during inpatient treatment, 43% vs. 63%; p = 0.02). Medical abortion was less effective at 50-63 days gestation than at less than 50 days gestation (complete abortion, 98% vs. 92.6%). 90% of women requiring curettage after medical abortion were at 50-63 days gestation. Gestation affected neither pain nor efficacy rates of vacuum aspiration, however. At follow-up 16 days after the procedure, the significant differences in the medical sequelae of the 2 procedures during and immediately after abortion disappeared. The short-lived sequelae did not greatly affect recovery times. For example, even though women who underwent vacuum aspiration required more time off work than those who underwent medical abortion (2.5 vs. 1.2 days; p = 0.007), the return of normal daily activities was essentially the same for both groups (0.6-1.3 vs. 0.8-1.5 days). These results suggest that at gestations of less than 50 days, the 2 procedures are equally effective and have similar 0-21 day complication rates. On the other hand, at 50-63 days gestation, medical abortion becomes more unpleasant and its efficacy begins to diminish. In conclusion, at higher gestations, women who do not prefer one method over another will probably find vacuum aspiration more acceptable than medical abortion.

Cross-talk among ROR alpha 1 and the Rev-erb family of orphan nuclear receptors.

We have cloned Rev-erb beta, a novel isoform of the Rev-erb alpha orphan nuclear receptor. The DNA binding domains of Rev-erb alpha and beta are highly related to each other and to the retinoic acid related orphan receptor (ROR)/RZR subfamily of nuclear receptors. Indeed, we find that all three receptors bind as monomers to the sequence AATGT-AGGTCA. Whereas ROR alpha 1 constitutively activates transcription through this sequence, both isoforms of Rev-erb are inactive. When coexpressed, both Rev-erb isoforms suppress the transcriptional activity of ROR alpha 1. Our data define Rev-erb and ROR/RZR as a family of related receptors with opposing activities on overlapping regulatory networks.

Fit of the uncemented femoral component and the use of cement influence the strain transfer the femoral cortex.

To determine whether the strain patterns produced in the femoral cortex after uncemented femoral arthroplasty are influenced by the fit of the component and whether these patterns are different from those of cemented components, cortical surface strains of cadaveric femurs subjected to loads simulating single-limb stance were measured before and after the insertion of uncemented, collared, straight-stemmed femoral components. The effects of press fit, loose fit, and precise fit of the components were evaluated and were contrasted to the strain patterns occurring after insertion of cemented femoral components. Strains varied markedly, depending on the fit of the stem of the uncemented femoral component within the isthmus. Nearly normal patterns of femoral strain were produced when the femoral stem was fit precisely at the isthmus, and the proximal femoral strains were similar to those of the intact state. In contrast, press fit and loose fit at the isthmus altered the strain patterns. The proximal medial axial strains were significantly reduced with press fit, to a mean of 39% of normal (p < 0.05), and increased with loose fit, to a mean of 141% of normal (p < 0.05). The prostheses fixed with cement showed a mean reduction in proximal medial axial strains to 33% of normal, which was comparable with press fit uncemented components even though the collar was well seated. Thus, our findings indicated that, in the immediate postoperative period, femoral strain patterns can be influenced by the fit of an uncemented component within the isthmus and by the use of cement.

Malonate produces striatal lesions by indirect NMDA receptor activation.

We previously showed that local striatal injections of malonate produce age-dependent excitotoxic lesions. In the present study volumetric analysis confirmed that malonate produces age-dependent striatal lesions. Pretreatment with the non-competitive and competitive NMDA receptor antagonists, MK-801 and LY274614, and with lamotrigine resulted in significant protection in 4-month-old animals. In vivo magnetic resonance imaging of lesion area showed a significant correlation of increasing lesion size and lactate production in rats ranging from 1 to 12 months of age. Histological evaluation showed NADPH-diaphorase neurons were spared. The results provide further evidence that a subtle impairment of energy metabolism may play a role in neurodegenerative diseases.

High assembly strains and femoral fractures produced during insertion of uncemented femoral components. A cadaver study.

The assembly strains produced in cadaver femurs during uncemented femoral arthroplasty were measured using strain gages and photoelastic coatings. Resecting the femoral neck, reaming the canal with power drills, and rasping with an optimal size rasp, as determined by preoperative radiographic templating, produced small assembly strains, up to 300 microstrain. Insertion of an optimal-size prosthesis after preparing the femoral canal with instruments the same size as the prosthesis produced moderate assembly strains, up to 1,000 microstrain. Half a millimeter press-fit of optimal prostheses produced larger assembly strains, up to 2,000 microstrain. Half a millimeter press-fit of a prosthesis that was also one size (1.0 mm) larger than that determined to be optimum produced even larger assembly strains (2,000-6,000 microstrain) and longitudinal linear fractures in the femoral cortex. Insertion of prostheses that were smaller than the rasps produced minimal strains in the femoral cortex. The magnitude of peak strains produced by press-fitting the femoral components and the small amounts of disparity between the size of the recess and the prosthesis necessary to produce these strains show the narrow range of tolerances available to the surgeon. Cementless femoral arthroplasty requires great care in preparing the femoral canal to the appropriate size as determined from preoperative templating, using accurate and precisely toleranced instrumentation and prosthetic components in order to avoid femoral fractures, yet obtain a stable fit.