The effect of backpack weight on the standing posture and balance of schoolgirls with adolescent idiopathic scoliosis and normal controls

Concerns have been raised regarding the effect of carrying a backpack on adolescent posture and balance, but the effect of backpack loading combined with other factors affecting balance, such as adolescent idiopathic scoliosis (AIS), has not been determined. This study examines the effects of backpack load on the posture and balance of schoolgirls with AIS and normal controls. The standing posture of 26 schoolgirls with mild AIS (mean age 13, Cobb angle 10-25 degrees ) and 20 age-matched normal schoolgirls were recorded without a backpack and while carrying a standard dual-strap backpack loaded at 7.5%, 10%, 12.5% and 15% of the subject's bodyweight (BW). Kinematics of the pelvis, trunk and head were recorded using a motion analysis system and centre of pressure (COP) data were recorded using a force platform. Reliable COP data could only be derived for 13 of the subjects with AIS. Increasing backpack load causes a significantly increased flexion of the trunk in relation to the pelvis and extension of the head in relation to the trunk, as well as increased antero-posterior range of COP motion. While backpack load appears to affect balance predominantly in the antero-posterior direction, differences between groups were more evident in the medio-lateral direction, with AIS subjects showing poor balance in this direction. Overall, carrying a backpack causes similar sagittal plane changes in posture and balance in both normal and AIS groups. Load size or subject group did not influence balance, but the additive effect of backpack carrying and AIS on postural control alters the risk of fall in this population. Therefore, load limit recommendations based on normal subjects should not be applicable to subjects with AIS.

Curve correction effect of rigid spinal orthosis in different recumbent positions in adolescent idiopathic scoliosis (AIS): a pilot MRI study

In this pilot cross-sectional study, the effectiveness of rigid spinal orthoses in the correction of spinal curvature of 14 patients with moderate adolescent idiopathic scoliosis (AIS) at different recumbent positions (supine, prone, right and left decubitus) was investigated. Using magnetic resonance (MR) imaging and multi-planar reconstruction technique, evaluation of the scoliotic spine in the coronal, sagittal and axial planes and the effect of spinal orthosis on AIS at different recumbent positions was studied. There was significant reduction of coronal Cobb's angle (p < 0.05) with bracing at all four recumbent positions and the maximal reduction was found in the prone position (18% reduction). The sagittal Cobb's angle was only significantly reduced at the supine position while the axial rotation did not change significantly in all positions.

A comparison of the clinical effectiveness of spinal orthoses manufactured using the conventional manual method and CAD/CAM method in the management of AIS

Spinal orthoses are commonly prescribed to patients with moderate AIS for prevention of further deterioration. In a conventional manufacturing method, plaster bandages are used to get patient's body contour and plaster cast is rectified manually. With the introduction of CAD/CAM system, a series of automated processes from body scanning to digital rectification and milling of positive model can be performed in a fast and accurate fashion. This project is to study the impact of CAD/CAM method as compared with the conventional method. In assessing the 147 recruited subjects fitted with spinal orthoses (43 subjects using conventional method and 104 subjects using CAD/CAM method), significant decreases (p<0.05) were found in the Cobb angles when comparing the pre-intervention data with that of the first year of intervention. Regarding the learning curve, Orthotists are getting more competent with the CAD/CAM technique in four years time. The mean productivity of the CAD/CAM method is 2.75 times higher than that of the conventional method. The CAD/CAM method could achieve similar clinical outcomes and with its high efficiency, could be considered as substitute for conventional methods in fabricating spinal orthoses for patients with AIS.

Effects of backpack loading on the pulmonary capacities of normal schoolgirls and those with adolescent idiopathic scoliosis

STUDY DESIGN

A prospective evaluation of the effects of backpack carriage on the pulmonary function of schoolgirls without spinal deformity versus those with adolescent idiopathic scoliosis (AIS).

OBJECTIVE

To establish if recommended backpack load limits for normal schoolchildren are also appropriate for study participants with AIS.

SUMMARY OF BACKGROUND DATA

The weight of schoolchildren's backpacks are of concern because of effects including compromise of pulmonary function. Impaired pulmonary function is also found with AIS, but the effect of backpack carriage on the respiratory parameters of schoolchildren with AIS has not previously been examined.

METHODS

Forced vital capacity (FVC), forced expiratory volume (FEV1), peak expiratory flow (PEF), and forced expiratory flow (FEF25-75%) were recorded in 17 girls (mean age, 12 years) with moderate AIS (Cobb angle, 26 degrees-50 degrees) and 18 girls (mean age, 11 years) without musculoskeletal deformity during carriage of a backpack loaded at 0%, 5%, 7.5%, 10%, 12.5%, and 15% body weight in random order. Absolute values and proportions of reference values were analyzed by repeated-measures analysis of variance. RESULTS.: No interaction between load and group was found, indicating that backpack loading has a similar effect on the pulmonary function of both normal and AIS groups. However, all recorded pulmonary parameters were found to be significantly lower in the AIS than normal group, significantly so for the referenced FVC and PEF. A significant decrease in FVC and FEV1 was found with increasing backpack load, and the load at which these changes were found to be significant was lower than those established in previous studies.

CONCLUSIONS

Pulmonary function may be more sensitive to backpack load than previously considered, especially when study participants with AIS are being considered, and the recommended loading limit of 10% body weight may not be applicable to schoolgirls with AIS.

Molecular mechanisms of survival and apoptosis in RAW 264.7 macrophages under oxidative stress

Organisms living in an aerobic environment are continuously exposed to reactive oxygen species (ROS). Apoptosis of cells can be induced by ROS and cells also develop negative feedback mechanisms to limit ROS induced cell death. In this study, RAW264.7 murine macrophage cells were treated with H(2)O(2) and cDNA microarray technique was used to produce gene expression profiles. We found that H(2)O(2) treatment caused up-regulation of stress, survival and apoptosis related genes, and down-regulation of growth and cell cycle promoting genes. Numerous genes of metabolism pathways showed special expression patterns under oxidative stress: glycolysis and lipid synthesis related genes were down-regulated whereas the genes of lipid catabolism and protein synthesis were up-regulated. We also identified several signaling molecules as ROS-responsive, including p53, Akt, NF-kappa B, ERK, JNK, p38, PKC and INF-gamma . They played important roles in the process of apoptosis or cell survival. Finally, an interactive pathway involved in cellular response to oxidative stress was proposed to provide some insight into the molecular events of apoptosis induced by ROS and the feedback mechanisms involved in cell survival.

The effect of load carriage on the gait of girls with adolescent idiopathic scoliosis and normal controls

Adolescent idiopathic scoliosis (AIS) and load-bearing both appear to place similar demands on gait, but no data regarding the combined effects of load-bearing gait in subjects with AIS could be found. The gait patterns of 22 normal adolescent girls and 28 girls with mild AIS (Cobb angle<25 degrees ) were recorded at backpack loads of 0, 7.5, 10, 12.5 and 15% body weight. Temporal-distance and joint kinematic, moment and power parameters were analyzed by repeated measures ANOVA. Findings showed that backpack carriage places an increased demand on the musculature of the lower limb and results in a gait characterized by reduced pelvic motion and greater hip flexion-extension. AIS has a generally similar effect on gait kinematics as backpack carriage, with AIS subjects having significantly longer double support durations, shorter single support durations and lower knee joint power generation and absorption than normal subjects. No interaction between backpack load and AIS was found however, although investigation of parameters indicating a critical response to load showed that this typically occurred at lower backpack loads (7.5% body weight) in the AIS group. Overall, both AIS and load-bearing place increased demands on gait, but carriage of a loaded backpack does not appear to cause any greater demand on subjects with AIS than normal controls.

The effect of backpack load on the gait of normal adolescent girls

Concerns regarding the effects of load carriage have led to recommendations that backpacks be limited to 10?-?15% of body weight, based on significant changes in physical performance. However, gait responses to backpack loads are not entirely consistent and there is a particular lack of data regarding load-bearing gait in adolescent females. Gait patterns of 22 normal adolescent girls were recorded at backpack loads of 0, 7.5, 10.0, 12.5 and 15.0% body weight. Temporal-distance, ground reaction force and joint kinematic, moment and power parameters were analysed by repeated measures ANOVA with factors of backpack load and side (left or right). Walking speed and cadence decreased significantly with increasing backpack load, while double support time increased. Kinematic changes were most marked at the proximal joints, with a decreased pelvic motion but a significant increase in the hip sagittal plane motion. Increased moments and power at the hip, knee and ankle showed increasing demand with backpack load. Parameters showed different responses to increasing load, and those that suggested a critical load indicated this to be approximately 10% body weight. While this may be due to a change in gait due to increased demand, further work is required to verify this and also to examine the cumulative effects of backpack load on the musculoskeletal system, which may be more appropriate in determining recommended load limits.

A comparison of treatment effectiveness between the CAD/CAM method and the manual method for managing adolescent idiopathic scoliosis

The treatment effectiveness of the CAD/CAM method and the manual method in managing adolescent idiopathic scoliosis (AIS) was compared. Forty subjects were recruited with twenty subjects for each method. The clinical parameters namely Cobb's angle and apical vertebral rotation were evaluated at the pre-brace and the immediate in-brace visits. The results demonstrated that orthotic treatments rendered by the CAD/CAM method and the conventional manual method were effective in providing initial control of Cobb's angle. Significant decreases (p < 0.05) were found between the pre-brace and immediate in-brace visits for both methods. The mean reductions of Cobb's angle were 12.8 degrees (41.9%) for the CAD/CAM method and 9.8 degrees (32.1%) for the manual method. An initial control of the apical vertebral rotation was not shown in this study. In the comparison between the CAD/CAM method and the manual method, no significant difference was found in the control of Cobb's angle and apical vertebral rotation. The current study demonstrated that the CAD/CAM method can provide similar result in the initial stage of treatment as compared with the manual method.

A work study of the CAD/CAM method and conventional manual method in the fabrication of spinal orthoses for patients with adolescent idiopathic scoliosis

A study was conducted to compare the CAD/CAM method with the conventional manual method in fabrication of spinal orthoses for patients with adolescent idiopathic scoliosis. Ten subjects were recruited for this study. Efficiency analyses of the two methods were performed from cast filling/ digitization process to completion of cast/image rectification. The dimensional changes of the casts/ models rectified by the two cast rectification methods were also investigated. The results demonstrated that the CAD/CAM method was faster than the conventional manual method in the studied processes. The mean rectification time of the CAD/CAM method was shorter than that of the conventional manual method by 108.3 min (63.5%). This indicated that the CAD/CAM method took about 1/3 of the time of the conventional manual to finish cast rectification. In the comparison of cast/image dimensional differences between the conventional manual method and the CAD/CAM method, five major dimensions in each of the five rectified regions namely the axilla, thoracic, lumbar, abdominal and pelvic regions were involved. There were no significant dimensional differences (p < 0.05) in 19 out of the 25 studied dimensions. This study demonstrated that the CAD/CAM system could save the time in the rectification process and offer a relatively high resemblance in cast rectification as compared with the conventional manual method.

Comparative study on the inclusion behavior between meso-tetrakis(4-N-ethylpyridiniurmyl)porphyrin and beta-cyclodextrin derivatives

5,10,15,20-Tetrakis(4-N-ethylpyridiniurmyl)porphyrin (TEPyP) formed 1:1 stoichiometry inclusion complexes with beta-cyclodextrin (beta-CD) and its derivatives including hydroxypropyl-beta-cyclodextrin (HP-beta-CD), sulfobutylether-beta-cyclodextrin (SBE-beta-CD) in basic aqueous solution. The supramolecular system was investigated by the methods of fluorescence, UV-vis absorption spectroscopy, nuclear magnetic resonance (NMR) technique. The inclusion ability of cyclodextrins exhibited remarkable difference for beta-CD, HP-beta-CD and SBE-beta-CD. Association constants as high as K=1.1 x 10(4) M(-1) in the case of HP-beta-CD/TEPyP and 2.0 x 10(5) M(-1) in the case of SBE-beta-CD/TEPyP complexes were determined, whereas a lower value (K=550 M(-1)) was given in the case of beta-CD/TEPyP. The results showed that hydrogen bonding and charge attraction play important roles in the processes of host-guest interaction. The interaction mechanism of inclusion processes could be explained by the analysis of NMR spectroscopy. The supramolecular assembly was formed. beta-CD and HP-beta-CD approached from the primary face of cavities of CDs.

Enhancement of prosthetics and orthotics learning and teaching through e-Learning technology and methodology

A Write-Once Publish-Everywhere model was used to create and deliver on-line clinical training and education for undergraduate prosthetics and orthotics students. This project consisted of three phases: developing multimedia learning and teaching tools, integrating these tools into the curriculum (combination of e-Learning and live practical sessions), and evaluating the outcomes. Video-based multimedia contents were captured and integrated with graphic, audio and text into a PowerPoint presentation software format. The web-based content was integrated into the WebCT platform for course management. Questionnaires were used to obtain student feedback on this e-Learning approach. Results were compared within the prosthetics and orthotics (P&O) programme, with other Health Sciences programmes, and overall with the University. P&O student responses were significantly higher than other groups for career relevance and problem solving. Qualitative feedback indicated that students appreciated the easy access, integrated and interactive approach of the text materials, concise PowerPoint presentation, demonstration video and the on-line case discussion via the WebCT platform. Educators appreciated the ability easily to maintain contents and publish the modules across multiple media without recreating the contents.

Critical review on non-operative management of adolescent idiopathic scoliosis

There are a number of different non-operative interventions which aim to control moderate adolescent idiopathic scoliosis (AIS) from progression. Clinicians may find difficulties in the selection of appropriate interventions for AIS. A comprehensive literature review was carried out to study all contemporary non-operative interventions, it was noted that rigid spinal orthoses apparently give more curve control; however, it would compromise the patient's quality of life via those inevitable factors--physical constraint, poor acceptance and psychological disturbance. There is a trend to develop more effective, acceptable and user-friendly interventions. Under such an aspiration, the theories and clinical evidence of different interventions should be developed along the clinical pathway of early intervention with reliable indicators/predictors, patient's active participation, dynamic control mechanism, holistic psychological and psychosocial considerations, and effective and long-lasting outcome.

Effect of different casting methods on adolescent idiopathic scoliosis

Scoliosis is a three-dimensional spinal deformity. Although orthotic treatment for moderate adolescent idiopathic scoliosis (AIS) has been well recognized, there are few studies documenting the effectiveness of different casting methods in the fabrication of thoracolumbo-sacral orthoses (TLSO). The current study was a retrospective clinical evaluation of the effectiveness of two commonly used casting methods namely, the frame casting method and the supine with traction casting method in the treatment of AIS. Eighty (80) female patients with AIS were recruited and they were all treated by TLSOs. The frame casting method was used in 37 patients while the remaining 43 patients were under the supine with traction casting method. The responses of spinal deformities under the two different casting methods were analyzed for the period from pre-brace to 2 years after bracing. The studied parameters included the AP Cobb's angle, the apical vertebral rotation and the trunk listing (cervico-sacral lateral offset). The results of the current study showed that the orthoses manufactured from the two casting methods could provide an effective control of AIS (change of Cobb's angle within (+/- 5 degrees). For the frame casting, the Cobb's angles at pre-brace and 2 years after off-brace were 36.0 degrees and 33.8 degrees respectively while for the supine with traction casting, the corresponding Cobb's angles were 32.7 degrees and 34.0 degrees. The frame casting method could give a better control of the apical vertebral rotation at the early stage of treatment (pre-brace = 18.2 degrees and the 4th month = 13.8 degrees while the supine with traction casting method was more effective in the long-term control of the trunk listing (pre-brace = 10mm and 2 years after off-brace = 3.3mm).

Quantum dots as strain- and metabolism-specific microbiological labels

Biologically conjugated quantum dots (QDs) have shown great promise as multiwavelength fluorescent labels for on-chip bioassays and eukaryotic cells. However, use of these photoluminescent nanocrystals in bacteria has not previously been reported, and their large size (3 to 10 nm) makes it unclear whether they inhibit bacterial recognition of attached molecules and whether they are able to pass through bacterial cell walls. Here we describe the use of conjugated CdSe QDs for strain- and metabolism-specific microbial labeling in a wide variety of bacteria and fungi, and our analysis was geared toward using receptors for a conjugated biomolecule that are present and active on the organism's surface. While cell surface molecules, such as glycoproteins, make excellent targets for conjugated QDs, internal labeling is inconsistent and leads to large spectral shifts compared with the original fluorescence, suggesting that there is breakup or dissolution of the QDs. Transmission electron microscopy of whole mounts and thin sections confirmed that bacteria are able to extract Cd and Se from QDs in a fashion dependent upon the QD surface conjugate.

[Current perspectives of orthogonal polarization spectral imaging in plastic surgery]

The technology of Orthogonal Polarization Spectral Imaging (OPSI), patented in the United States in 1999, has been heralded as an alternative to conventional intravital microscopy for several reasons, including ease of application and ability to perform continued observations. In the following examples, OPSI was applied to reconstructive plastic surgery. Two experimental and one clinical model are presented. Currently, the image quality does not allow a qualitative analysis of the microvasculature. The data analysis of images remains inconclusive. However, a technically modified version with improved image resolution and software could become a valuable experimental as well as clinical tool in the field of reconstructive plastic surgery in the future.

Effect of using prismatic eye lenses on the posture of patients with adolescent idiopathic scoliosis measured by 3-d motion analysis

This is a preliminary investigation to detect the body sway and postural changes of patients with AIS under different spatial images. Two pairs of low-power prismatic eye lenses (Fresnel prisms) with 5 dioptre and 10 dioptre were used. In the experiment, the apices of the prisms were orientated randomly at every 22.5 degrees from 0 degrees to 360 degrees to test changes. Four patients with mean age of 11 and Cobb's angle of 30 degrees were recruited and the results showed that the low-power prisms at specific orientations (157.5 degrees and 180 degrees) could cause positive postural changes (2.1 degrees-2.7 degrees reduction of angle of trunk mis-alignment) measured by 3-D motion analysis. This might be used for controlling their scoliotic curves by induced visual bio-feedback. Apart from this laboratory test, a longitudinal study is necessary to investigate the long-term effect of the prisms at different powers and orientations (under both static and dynamic situations) on the patient's posture, spinal muscular activities, vision, eye-hand coordination, psychological state and other daily activities before it becomes an alternative management of AIS.

Recent advances in radiotherapy for head and neck cancers

Advancements in surgery have made it possible to resect cancers that had previously been regarded as incurable. Similarly, new developments in radiation oncology have helped improve the outlook for patients with locally advanced or recurrent head and neck cancers. Among these advancements are refinements in altered fractionation, three-dimensional conformal radiotherapy, intensity-modulated radiotherapy, stereotactic radiosurgery and fractionated stereotactic radiotherapy, neutron-beam radiotherapy, charged-particle radiotherapy, and intraoperative radiotherapy. These recent developments have allowed radiation oncologists to escalate the dose of radiation delivered to tumors while minimizing the dose delivered to surrounding normal tissue. Additionally, more continues to be learned about the optimum delivery of chemotherapy. This article provides an update on the status of these new developments in the treatment of head and neck cancers.

Ceruloplasmin promotes iron uptake rather than release in BT325 cells

This study was initiated to investigate the mechanism of ceruloplasmin (CP)-mediated iron release from brain cells using BT325 cells (a glioblastoma cell line); however, negative results were obtained. The BT325 cells were preloaded with 1 microM 59Fe2+ in sucrose (pH 5.8) for 60 min, and then with CP (0-300 microg/ml) for 30 min at 37 degrees C. The addition of CP, either at low (25 microg/ml) or high (300 microg/ml) concentrations, did not lead to a significant change in iron release from iron-loaded BT325 cells. No significant difference in total iron of cells was found between all CP treated groups and the control (P>0.05). Although apotransferrin (apoTf) was shown to have a role in iron release from the cells, the effect of apoTf was not significantly affected by the addition of different concentrations of CP. When the cells were incubated with 1 microM 59Fe2+ in the presence of varying amounts of CP for 30 min at 37 degrees C, it was found that CP increased iron uptake. The total iron uptake by BT325 cells in CP treatment groups (25, 75, 150, 300 microg/ml) was significantly higher than that in the control (no CP addition) (all P<0.01). Furthermore, in contrast to our expectation, CP was shown to promote significantly iron uptake in not only iron-sufficient but also iron-deficient cells. These results showed that CP had a role in iron uptake rather than release in BT325 cells.

Effect of receptor phosphorylation on the binding between IRS-1 and IGF-1R as revealed by surface plasmon resonance biosensor

A receptor binding assay based on the surface plasmon resonance (SPR) biosensor technique was developed to study the interaction between insulin-like growth factor-1 receptor (IGF-1R) and its intracellular substrate protein insulin receptor substrate-1 (IRS-1). The sensor surface was modified with anti-IGF-1R (alpha-subunit) monoclonal antibodies for the capturing of the receptor-containing membrane fragments from cell lysates. The IGF-1R was successfully immobilized on the sensor surface with binding capability for its intracellular substrates. SPR measurements showed that the tyrosine phosphorylation of IGF-1R induced by its extracellular ligand insulin-like growth factor-1 caused the receptor to bind with IRS-1 10 times faster than the unactivated receptor. As a result, the affinity constants of IRS-1 to phosphorylated and unphosphorylated IGF-1R were (8.06+/-5.18)x10(9) M(-1) and (9.81+/-4.61)x10(8) M(-1), respectively.

Effectiveness of audio-biofeedback in postural training for adolescent idiopathic scoliosis patients

The possibility of using learned physiological responses in control of progressive adolescent idiopathic scoliosis (AIS) was investigated. Sixteen (16) AIS patients with progressing or high-risk curves (Cobb's angle between 25 degrees and 35 degrees at start and reducible by lateral bending) were fitted with a device with tone alarm for poor posture. In the first 18 months of application, 3 patients defaulted and 4 showed curve progression > 10 degrees (2 changed to rigid spinal orthoses and 2 underwent surgery). The curves for the other 9 patients were kept under control (within +/- 5 degrees of Cobb's angle) and 5 of them have reached skeletal maturity and terminated the application. The remaining 4 patients were still using the devices until skeletal maturity or curve progression. The curve control rate was 69%. A long-lasting active spinal control could be achieved through the patient's own spinal muscles. Nevertheless, before the postural training device could become a treatment modality, a long-term study for more AIS patients was necessary. This project is ongoing in the Duchess of Kent Children's Hospital, Sandy Bay, Hong Kong.

Effectiveness and biomechanics of spinal orthoses in the treatment of adolescent idiopathic scoliosis (AIS)

In this prospective study, the effectiveness and biomechanical factors of spinal orthoses in the treatment of moderate adolescent idiopathic scoliosis (AIS) patients were investigated. In the first 20 months of orthotic treatment, the values of standing AP Cobb's angle, apical vertebral rotation, lumbar lordosis as well as thoracic kyphosis showed significant reduction (P<0.05), however, the angle of trunk inclination and trunk listing did not. The values of those reducible parameters reached their lowest values within the first 12 months of orthotic treatment and then the values gradually increased but they were still below the pre-brace values. The mean pressure of The pressure pads was found to be 7.09 +/- 1.77 kPa (53.2 +/- 13.3 mmHg) while the mean tension of the straps was 26.8 +/- 5.2N. The standing AP Cobb's angle strongly correlated with the pad pressure (correlation coefficient=0.931, p<(.05) and strap tension (correlation coefficient=0.914, p<0.05). The strap tension and pad pressure strongly correlated and the correlation coefficient was 0.873 (p<0.05). This suggests that in the consideration of biomechanical function of spinal orthoses, the focus may be upon how tightly the orthosis was fastened and if the location and direction of the pressure pads are the correct. Therefore, for enhancing independent standard tension should be set in each strap, and regular and close monitoring is needed.

Potency preservation after three-dimensional conformal radiotherapy for prostate cancer: preliminary results

We sought to assess potency preservation after three-dimensional conformal radiotherapy (3D-CRT) in prostate cancer patients eligible for radical prostatectomy, conventional radiotherapy, 3D-CRT, or transperineal prostate implantation. Patients with more advanced disease are commonly treated with hormonal therapy, which can cause impotence, and were consequently excluded from the analysis. Between December 1991 and June 1998, 198 prostate cancer patients were treated with 3D-CRT at the University of California, Davis Medical Center. Fifty-two of these patients had a pretreatment prostate-specific antigen (PSA) level of 10.0 ng/ml or less, a Gleason score of 6 or less, and a 1997 AJCC clinical stage T1bN0M0 to T2bN0M0. One patient was not evaluable. None of the 51 evaluable patients had diabetes mellitus. In 40 patients, the prostate gland only was irradiated to a total dose of 66 to 79.2 Gy by using daily 1.8-Gy fractions. In 11 patients, the prostate and seminal vesicles were treated to 44 to 55.8 Gy. Lymph nodes were not included in the clinical target volume. The median age was 68 years, and the median length of follow-up was 15 months. Potency in this study is defined as an erection sufficient for vaginal penetration. Kaplan-Meier analysis was used to describe potency as a function of time after 3D-CRT. Of the 51 evaluable patients, 35 (69%) were potent, 15 were impotent, and 1 was sexually inactive before 3D-CRT. Kaplan-Meier estimates of the potency preservation rates 1, 2, and 3 years after 3D-CRT are 100%, 83%, and 63%, respectively. On multivariate analysis, age, total radiation dose, and a history of transurethral resection of the prostate did not significantly affect potency preservation rates. Three (43%) of 7 patients who became impotent after 3D-CRT and used sildenafil were subsequently able to achieve erections sufficient for vaginal penetration. The preliminary results reported herein suggest that approximately two thirds of prostate cancer patients will retain their potency 3 years after 3D-CRT. Further follow-up is necessary to assess long-term potency after 3D-CRT. Sildenafil should be considered in patients who develop radiation-induced impotence.