Learning curve of robot-assisted total knee arthroplasty and its effects on implant position in asian patients: a prospective study.

BACKGROUND: Robot-assisted total knee arthroplasty (r-TKA) can reportedly achieve more accurate implant positioning than conventional total knee arthroplasty (c-TKA), although its learning curve is controversial. Moreover, few studies have investigated r-TKA in Asians, who have different anatomical characteristics. This study aimed to determine the learning curve for r-TKA and compare implant positions between r-TKA and c-TKA according to the learning curve in Asian patients. METHODS: This prospective study included 50 consecutive c-TKAs (group C), followed by 50 consecutive r-TKAs conducted using the MAKO robotic system (Stryker, USA). Cumulative summation analyses were performed to assess the learning curve for operative time in r-TKA. Accordingly, the r-TKA cases were divided into the initial (group I) and proficiency cases (group P). The femoral and tibial component positions in the coronal, sagittal, and axial planes and lower limb alignment were compared among the three groups. RESULTS: r-TKA was associated with a learning curve for operative time in 18 cases. The operative time was significantly shorter in groups C and P than that in group I, with no significant difference between groups C and P. Groups I and P demonstrated fewer outliers with respect to lower limb alignment, femoral component coronal position, axial position, and tibial component sagittal position than those in group C, with no significant difference between groups I and P. CONCLUSION: The operative time did not differ significantly between r-TKA and c-TKA after the learning curve. Surgeons could expect more accurate and reproducible lower limb alignment and implant positioning with r-TKA in Asian patients, irrespective of the learning curve.

Preoperative patellar bone marrow lesions with full thickness cartilage defects correlate with residual anterior knee pain in total knee arthroplasty without patellar resurfacing.

PURPOSE: Residual anterior knee pain is one of the most common problems after total knee arthroplasty (TKA). However, the contributing factors affecting postoperative anterior knee pain (AKP) remain poorly understood. This study aimed to evaluate the effect of preoperative patellar bone marrow lesions (BMLs) and patellar cartilage defects on postoperative AKP after patellar non-resurfacing TKA. METHODS: This retrospective study included 336 patients who underwent unilateral TKA without patella resurfacing. All patients underwent preoperative magnetic resonance imaging (MRI) to assess the presence of BMLs and the degree of cartilage defects in the patella. Patients were categorized into four groups according to the presence of BMLs (with or without BMLs) and the degree of cartilage defects (with or without full thickness cartilage defects). The Kujala Anterior Knee Pain Scale (AKPS) and the Hospital for Special Surgery Knee Rating Scale (HSS) scores at 2 years after TKA were compared among the groups. RESULTS: Preoperative BMLs in the patella were found in 132 (39.3%) of 336 cases. Among the four groups, the group with both BMLs and full-thickness cartilage defects demonstrated significantly lower AKPS compared to the other groups at 2 years after TKA (p < 0.01), but no significant difference was shown in the HSS scores, between these groups. There were no significant differences in either AKPS or HSS scores among the other three patient groups. CONCLUSIONS: The presence of preoperative BMLs with full-thickness cartilage defects in the patella was associated with worse postoperative AKP after TKA without patella resurfacing. Patella resurfacing should be considered in this patient group to minimize the risk of developing residual AKP after TKA. LEVEL OF EVIDENCE: III.

The Association of Intravenous Iron Administered the Day before Total Knee Arthroplasty with Postoperative Anemia and Functional Recovery.

Background and Objectives: Total knee arthroplasty (TKA) involves blood loss, increasing the risk of postoperative anemia and delayed functional recovery. Intravenous (IV) iron supplementation limits postoperative anemia; however, the effectiveness of IV iron, administered one day before TKA, on postoperative anemia and functional recovery has scarcely been studied. Materials and Methods: We conducted a retrospective cohort study with propensity score matching using two consecutive groups of patients who underwent TKA using tranexamic acid: the iron group received 500 mg ferric derisomaltose intravenously one day before surgery (n = 46); the non-iron group did not (n = 46). Hemoglobin (Hb) level was determined at postoperative days (PODs) 2, 4, 6, 14, and 30. Ferritin, transferrin saturation (TSAT), and functional iron deficiency anemia (IDA) rate were measured at PODs 2, 4, 6, and 14. Length of hospital stay and transfusion rate were also evaluated. Results: The iron group had higher Hb levels at PODs 6, 14, and 30 and higher ferritin and TSAT at PODs 2, 4, 6, and 14. The functional IDA rate was significantly higher in the non-iron group at PODs 2, 4, 6, and 14. Length of hospital stay was significantly shorter in the iron group; however, the rate of transfusion did not differ between the two groups. Conclusions: IV iron administered one day before TKA was associated with postoperative anemia recovery and length of hospital stay; however, it did not lower the postoperative transfusion rate.

Comparing the Anterior-Based Muscle-Sparing Approach with the Direct Anterior Approach in Hip Arthroplasty: A Systematic Review and Pairwise Meta-Analysis.

Background and Objectives: The anterior-based muscle-sparing (ABMS) approach, which utilizes the interval between the tensor fasciae latae posteriorly, offers several advantages, such as the reduced risk of nerve injury and the freedom to choose various implants. Herein, we aimed to compare the outcome of ABMS to the direct anterior (DA) approach using pairwise meta-analysis techniques. Materials and Methods: A systematic search of the MEDLINE (PUBMED), Embase, and Cochrane Library databases was performed for studies published up to 7 June 2023, which compared the ABMS approach with the DA approach for hip arthroplasty. We compared (1) perioperative outcomes (operation time, visual analog scale (VAS) score, total opioid consumption, length of hospital stay (LOS), and the number of patients discharged to their homes); (2) postoperative complications (neuropraxia/nerve injury, dislocation, surgical site infection, intraoperative fracture, and reoperation rate); and (3) implant position (cup inclination, cup anteversion, and stem alignment). Results: Ten studies were eligible for meta-analysis, including 1737 patients who underwent hip arthroplasty with the ABMS approach and 1979 with the DA approach. The pooled analysis showed no differences in all outcome variables, including perioperative outcomes, postoperative complications, and the implant position between the two surgical approaches. Conclusions: In current meta-analysis, the ABMS approach demonstrated comparable results to the conventional DA approach in terms of both clinical and radiologic outcomes as well as postoperative complications. Furthermore, the ABMS approach has the advantage of a broader indication and fewer limitations in terms of the surgical position compared to the DA approach. Therefore, the ABMS approach can be even more beneficial as an option within MSA, surpassing the utility of the DA approach.

Effectiveness of Intravenous Non-Opioid Analgesics for Postoperative Pain Management of in Patients Undergoing Hip Surgery: A Systematic Review and Meta-Analysis.

Background and Objectives: Intravenous (IV) non-opioid analgesics (NOAs) have been extensively investigated as a multimodal analgesic strategy for the management of acute pain after hip surgery. This pair-wise meta-analysis examined IV NOA effects following hip surgery. Materials and Methods: A systematic search of the MEDLINE (PUBMED), Embase, and Cochrane Library databases was performed for studies investigating the effect of IV NOA for postoperative pain management following hip surgery up to 7 June 2023. We compared in-admission opioid use, postoperative VAS (visual analogue scale) score, hospital stay duration, and opioid-related adverse events between IV NOA and control groups. Results: Seven studies were included with a total of 953 patients who underwent hip surgery. Of these, 478 underwent IV NOA treatment, and 475 did not. The IV NOA groups had lower opioid use within 24-h following hip surgery (SMD, -0.48; 95% CI, -0.66 to -0.30; p < 0.01), lower VAS score (SMD, -0.47; 95% CI, -0.79 to -0.16; p < 0.01), shorter hospital stay (SMD, -0.28; 95% CI, -0.44 to -0.12; p < 0.01), and lower incidence of nausea and vomiting (OR, 0.32; 95% CI, 0.15 to 0.67; p < 0.01) compared with the control groups. Conclusions: This meta-analysis demonstrated that IV NOA administration following hip surgery may have more favorable postoperative outcomes than those in control groups.

Combined use of topical intraarticular tranexamic acid and rivaroxaban in total knee arthroplasty safely reduces blood loss, transfusion rates, and wound complications without increasing the risk of thrombosis.

BACKGROUND: Blood loss and deep vein thrombosis (DVT) are important complications after total knee arthroplasty (TKA). Topical tranexamic acid (TXA) effectively reduces wound bleeding but may elevate the risk of DVT. In contrast, rivaroxaban potently prevents DVT but has been associated with bleeding complications. The simultaneous use of topical TXA and rivaroxaban in TKA has not been much investigated. METHODS: A retrospective cohort study was conducted with two consecutive groups of patients who underwent TKA. Intraoperatively, one group (RVTX group) received topical, intraarticular TXA, while the other (RV group) did not. Both groups were administered rivaroxaban postoperatively for 14 days and underwent Doppler ultrasound for DVT screening. After propensity score matching, both groups consisted of 52 patients (104 patients in total) and were compared regarding total drain output, nadir haemoglobin (Hb), maximum Hb decrease, calculated total blood loss, transfusion rate, and incidence of DVT and wound complications. RESULTS: Both groups showed no significant differences in the propensity-matched variables of age, sex, body mass index, American Society of Anesthesiologists physical status score, and preoperative Hb. The RVTX group showed a significantly higher nadir Hb (p < 0.001), lower drain output (p < 0.001), Hb decrease (p = 0.015), total blood loss (p < 0.001), and rate of transfusion (p < 0.001) and fewer wound complications (p = 0.027). However, the incidence of DVT (p = 1.000) did not differ significantly between the two groups, and all cases were asymptomatic. CONCLUSIONS: The combined use of intraarticular topical TXA with rivaroxaban in patients undergoing TKA is a safe and effective method to reduce blood loss, the need for transfusion, and wound complications without elevating the risk of DVT.

Do the Clinical and Radiological Features of Knees with Mucoid Degeneration of the Anterior Cruciate Ligament Differ According to Knee Osteoarthritis Status?

Background: The etiology and pathology of mucoid degeneration of the anterior cruciate ligament (MD-ACL) remain poorly understood. MD-ACL may be associated with knee osteoarthritis (OA) or a mechanism other than OA. This study evaluated the radiological differences between knees with MD-ACL and those with a normal ACL and compared the clinical and radiological features of knees with MD-ACL according to the knee OA status. Methods: This retrospective study compared the radiological features of the intercondylar notch width index (NWI) and posterior tibial slope (PTS) of 67 MD-ACL patients (MD group) and 67 age-, sex-, and OA grade-matched patients with a normal ACL (control group). During the subgroup analysis, MD-ACL patients were divided into the non-OA subgroup (n = 41) and OA subgroup (n = 26). The pain location and characteristics of the knee, PTS, and NWI were compared between these subgroups. Results: Compared to the control group, the MD group had a lower NWI (0.26 ± 0.03 vs. 0.28 ± 0.01, p < 0.001) and a larger PTS (11.3° ± 3.0° vs. 9.2° ± 2.5°, p < 0.001). During the subgroup analysis, the most common pain locations were the posterior and medial aspects of the knee in the non-OA subgroup (43.9%) and OA subgroup (53.8%), respectively. Pain on terminal flexion was the most common pain characteristic in both subgroups (non-OA subgroup, 73.1%; OA subgroup, 53.8%). The PTS was not different between subgroups (11.7° ± 3.2° in the non-OA subgroup vs. 10.6° ± 2.7° in the OA subgroup; p = 0.159). However, the non-OA subgroup had a lower NWI than the OA subgroup (0.25 ± 0.03 vs. 0.28 ± 0.02, p = 0.001). Conclusions: Patients with MD-ACL had a lower NWI and a larger PTS than patients with a normal ACL. Furthermore, the clinical and radiological features of MD-ACL differed according to the knee OA status. A narrow intercondylar notch may be more closely associated with the development of MD-ACL without OA.

Incidence of Convergence Between Distally and Anteriorly Oriented ALL Femoral Tunnels and ACL Femoral Tunnels in Combined ACL and ALL Reconstruction: 3-Dimensional Computed Tomography Analysis of 227 Patients.

BACKGROUND: Adjusting the direction of the anterolateral ligament (ALL) femoral tunnel is suggested to avoid tunnel convergence during anterior cruciate ligament (ACL) reconstruction. Yet, there has been no in vivo clinical study reporting the effect of changing the direction of the ALL tunnel on the incidence of convergence with the ACL tunnel. PURPOSE: To report the incidence of convergence between the ACL femoral tunnel and a distally and anteriorly directed ALL femoral tunnel and to determine a safe distal angle and anterior angle. STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: A total of 227 patients undergoing concomitant ALL and anatomic single-bundle ACL reconstruction between January 2020 and December 2022 were retrospectively reviewed. The tunnel convergence rate, angular orientation of the tunnels, and distance between tunnels were obtained using postoperative computed tomography. The patients were grouped based on the direction of the ALL tunnel (transverse vs distal anterior) and the presence of tunnel convergence (convergence vs no convergence). RESULTS: The overall tunnel convergence rate was 53.3% (121/227 patients). Tunnel convergence was observed less frequently in the distal anterior group (33.7%) than in the transverse group (65.2%) (P < .001). The no convergence group showed an ALL tunnel oriented more distally (20.2°± 11.1°) and anteriorly (19.5°± 10.2°) compared with the convergence group (8.7°± 6.5° and 6.9°± 5.3°, respectively) (P = .005 and P = .008, respectively). There were no cases of tunnel convergence for ALL tunnels >24.3° distally and >25.5° anteriorly. There was no difference in the angle of the ACL femoral tunnel between all groups. CONCLUSION: A distally and anteriorly directed ALL femoral tunnel reduced the incidence of convergence with the ACL femoral tunnel. A distal angle >24.3° and an anterior angle >25.5° of an ALL tunnel are suggested to safely avoid convergence with the ACL tunnel.

Validation of Sagittal age-adjusted Score in Predicting Proximal Junctional Kyphosis/Failure and Clinical Outcomes Following Adult Spinal Deformity Surgery.

STUDY DESIGN: Retrospective study. OBJECTIVES: To validate the sagittal age-adjusted score (SAAS) in predicting proximal junctional kyphosis/failure (PJK/F) and good clinical outcomes following adult spinal deformity (ASD) surgery. SUMMARY OF BACKGROUND DATA: SAAS is a relatively new assessment system that incorporates age-adjusted sagittal parameters of pelvic incidence (PI) - lumbar lordosis (LL), pelvic tilt (PT), and T1 pelvic angle (TPA) to predict the PJK/F. External validation is required to verify its clinical usefulness. METHODS: We included patients with ASD undergoing ≥5-level fusion including the sacrum or pelvis. SAAS was calculated based on the scores of the three components: PI-LL, PT, and TPA. PJK/F rates and clinical outcomes were compared among the correction categories (undercorrection, matched correction, and overcorrection) for the SAAS as well as for each of the three components. PJK/F rates were compared according to the correction groups of the sagittal components and total SAAS using the chi-square test. Receiver operating characteristic (ROC) analysis was performed to evaluate the predictive ability of overcorrection to develop PJK/F for the three sagittal parameters and SAAS. PROMs at final follow-up were compared among correction groups using ANOVA with Bonferroni post-hoc corrections. RESULTS: A total 411 patients were included in the study (mean age: 69.3 y, mean body mass index: 25.9 kg/m2, total levels fused: 7.7 levels, and follow-up duration: 43.3 mo). Postoperative SAAS categories were as follow: undercorrection (13.4%), matched correction (30.2%), and overcorrection (56.4%). The PJK/F rates were significantly higher in the overcorrection group relative to PI-LL component (P=0.001) as well as SAAS (P=0.038) compared to undercorrection or matched correction groups. The clinical outcomes were best in patients who achieved matched correction relative to PI-LL component as well as SAAS compared to the other correction groups. However, the differentiating power of clinical outcomes across the correction categories was greater in the PI-LL component than in the SAAS. CONCLUSION: This study validated the efficacy of SAAS system to differentiate PJK/F development and good clinical outcomes. However, its differentiating power seems to be largely attributable to the function of the PI-LL component, as the PI-LL correction status better predicted PJK/F risk and clinical outcomes than SAAS.

Do Preoperative Vastus Medialis Volume and Quality Affect Functional Outcomes after Total Knee Arthroplasty?

BACKGROUND: Vastus medialis function has been implicated in the development and progression of knee osteoarthritis; however, studies evaluating the influence of its preoperative volume and quality on functional outcomes following total knee arthroplasty (TKA) remain scarce. This study aimed to determine the association between vastus medialis volume, quality, and clinical outcomes after TKA. METHODS: Among the patients who underwent unilateral TKA, 92 who had undergone magnetic resonance imaging (MRI) before TKA were included. Preoperative vastus medialis volume and quality were assessed using the cross-sectional area (CSA) and fat infiltration ratio on MRI. Clinical outcomes were evaluated using the Knee Society knee score (KSKS) and Knee Society function score (KSFS) at baseline and 1 year after surgery. The relationships between preoperative CSA, fatty infiltration ratio, and clinical outcomes were analyzed using univariate and multivariate linear regression. RESULTS: Only the fatty infiltration ratio was significantly associated with postoperative KSFS in the univariate linear regression analysis. In the multivariate linear regression analysis, age and fatty infiltration ratio were significantly associated with postoperative KSFS. CONCLUSIONS: Increased vastus medialis fat infiltration is associated with worse functional outcomes after TKA. Preserving vastus medialis quality could improve functional outcomes, and surgeons should encourage patients to perform quadriceps strengthening exercises before surgery.

Suprascapular Nerve Block Is an Effective Pain Control Method in Patients Undergoing Arthroscopic Rotator Cuff Repair: A Randomized Controlled Trial.

BACKGROUND: Effective pain control in patients who have undergone arthroscopic rotator cuff surgery improves functional recovery and early mobilization. Interscalene blocks (ISBs), a widely used approach, are safe and provide fast pain relief; however, they are associated with complications. Another pain management strategy is the use of a suprascapular nerve block (SSNB). HYPOTHESIS: We hypothesized that indwelling SSNB catheters are a more effective pain control method than single-shot ISBs. We also hypothesized that indwelling SSNB catheters will reduce the level of rebound pain and the demand for opioid analgesics. STUDY DESIGN: Randomized controlled trial; Level of evidence, 1. METHODS: Included in this study were 93 patients who underwent arthroscopic rotator cuff surgery between May 2012 and January 2019. These patients were assigned to either the indwelling SSNB catheter group, the single-shot ISB group, or the control (sham/placebo) group (31 patients per group). Level of pain was measured with a visual analog scale (VAS; 0 to 10 [worst pain]) on the day of the operation. The preoperative VAS score was recorded at 6 AM on the day of operation, and the postoperative scores were recorded at 1, 8, and 16 hours after surgery and then every 8 hours until postoperative day 3. RESULTS: The VAS pain scores were lower in the SSNB and ISB groups than in the control group up to postoperative hour (POH) 8, with the most significant difference at POH 8. At POH 1 and POH 8, the mean VAS scores for each group were 2.29 and 1.74 (SSNB), 2.59 and 2.50 (ISB), and 3.42 and 4.48 (control), respectively. VAS scores in the SSNB and ISB groups were consistently <3, compared with a mean VAS score of 3.1 ± 1.58 in the control group (P < .001). Compared with the ISB group, the SSNB group had significantly fewer side effects such as rebound pain duration as well as lower VAS scores (P < .001). CONCLUSION: VAS scores were the lowest in the indwelling SSNB catheter group, with the most pronounced between-group difference in VAS scores at POH 8. Severity and recurring frequency of pain were lower in the indwelling SSNB catheter group than in the single-shot ISB group.

Preoperative rotational assessment of the distal femur with CT may cause femoral component malrotation in TKA.

BACKGROUND: Before total knee arthroplasty (TKA), rotational assessment of the distal femur can be performed using either magnetic resonance imaging (MRI) or computed tomography (CT). Until now, there has been no study comparing the two modalities regarding rotational assessment of the distal femur in the same patients. METHODS: We retrospectively reviewed the preoperative CT and MRI images of 110 knees in 110 patients who underwent TKA. In the axial planes of CT and MRI scan, the posterior condylar axis (PCA), anatomical transepicondylar axis (aTEA), and perpendicular line to anteroposterior axis (pAPA) were identified; the angles between these studied lines were calculated. During TKA, the angles measured on the preoperative CT and MRI were compared with the measurements obtained in the intraoperative field. RESULTS: The mean aTEA-PCA angle was 6.2 ± 1.9° with CT and 5.1 ± 1.8° with MRI. The mean pAPA-PCA angle was 4.7 ± 2.1° with CT and 3.5 ± 2.0° with MRI. The mean aTEA-PCA (1.1 ± 1.3°, p = 0.001) and pAPA-PCA (1.2 ± 1.2°, p = 0.012) angles significantly differed between CT and MRI. Intra-operatively, the mean aTEA-PCA angle was 4.7 ± 1.1° and the mean pAPA-PCA angle was 3.2 ± 0.9°. Reliability analysis between the preoperative CT/MRI and the intraoperative measurements gave kappa values of 0.72 for aTEA-PCA and 0.66 for pAPA-PCA with CT, and 0.82 for aTEA-PCA and 0.84 for pAPA-PCA with MRI. CONCLUSIONS: Preoperative rotational assessment of the distal femur with CT may cause higher external rotation of femoral component in TKA.

Safety evaluation of drowsy driving advisory system: Alabama case study.

INTRODUCTION: The present study discusses roles, characteristics, and safety assessment of a drowsy driving advisory (DDA) system, implemented on rural interstates of Alabama. The DDA system is an engineering countermeasure designed to reduce the likelihood of drowsy driving crashes. It consists of a series of roadside signs with warning and advisory messages for drowsy drivers. The DDA system was implemented upstream of rural rest areas based on a comprehensive crash analysis. METHOD: A post-implementation study was conducted three years after the DDA system implementation to assess its safety effects. An empirical bayes (EB) method along with predictive methods of the Highway Safety Manual was used in the safety assessment. To overcome the underreported issue of drowsy driving crashes in the crash analysis, the present study used a concept called, expanded definition of drowsy driving (EDD) crashes. RESULT: The analysis found that the DDA system could reduce total and EDD crashes by 64% and 49%, respectively. It is important to note that such huge crash reduction effects are due to a combined effect of both rest areas and the DDA system, not because of a single treatment. The safety effect of a rest area itself, without considering the effect of the DDA system, was also investigated. Results show that total and EDD crashes would increase about 12-45% and 5-33%, respectively if there is no presence of a rest area. CONCLUSION: Our findings conclude that the DDA system could significantly reduce both total and drowsy driving crashes when it cooperates with a rest area facility. Practical Application: The findings also provide the guidance of using the DDA system on high-speed roads as a safety countermeasure of drowsy driving crashes. Readers can find details of the DDA system used in this study with its layout, dimension, and roadside safety messages.

Arthroscopic Treatment of Osteochondral Lesions of the Talus in a Suspended Position With the Patient in a Prone Position.

BACKGROUND: The purpose of this study was to evaluate the clinical results and the safety of arthroscopic microfracture with the ankle suspended on a shoulder-holding traction frame for simultaneous anterior and posterior ankle arthroscopy in the prone position. METHODS: Between May 2010 and January 2016, 31 patients with posterior osteochondral lesions of the talus (OLTs) were treated with arthroscopic microfracture in a suspended position with the patient prone. Ankle distraction was achieved by suspending the affected ankle on a shoulder-holding traction frame. The 100 mm visual analog scale (VAS) and the Foot Function Index (FFI) were checked preoperatively and at final follow-up. Postoperative complications related to the suspended position were analyzed. Lower leg intramuscular compartment pressure was checked after the surgery to determine if there was any risk of compartment syndrome. RESULTS: The mean 100-mm VAS score, and FFI improved from 62.8 ±11.3 and 48.5 ± 12.1, respectively, preoperatively to 15.8 ± 10.4 and 16.4 ± 9.2, respectively, at final follow-up (P = .025, and P = .005, respectively). The mean anterior, lateral, superficial posterior, and deep posterior compartment pressures were 7.3 ± 1.5, 8.1 ± 1.1, 5.6 ± 1.9, and 9.2 ± 2.4 mmHg, respectively. No compartment syndrome occurred. CONCLUSION: Arthroscopic treatment of OLT in a prone position with the ankle suspended on a shoulder-holding traction frame allowed the use of simultaneous anterior and posterior portals for viewing and instrumentation without major operative complications, such as compartment syndrome. LEVEL OF EVIDENCE: Level IV, retrospective case series.

Structure and expression analysis of the cecropin-E gene from the silkworm, Bombyx mori.

Cecropins belong to the antibacterial peptides family and are induced after injection of bacteria or their cell-wall components. By silkworm cDNA microarray analysis, a novel type of Cecropin family gene was identified as a cDNA up-regulated in early embryo, 1 day after oviposition. The cDNA isolated was 394 bp with 198 ORF translating 65 amino acids, encoding BmCecropin-E (BmCec-E). Using Southern hybridization and genome search analysis, the number of BmCec-E gene was estimated to be at least two per haploid, which consisted of two exons, as in other Cecropin family members. BmCec-E mRNA was expressed transiently 1 day after egg-laying (AEL, germ-band formation stage), and was specifically expressed in the degenerating intestine during the pre-pupal and pupal stages, unlike other Cecropin family genes. Immune challenge analysis showed that BmCec-E gene expression was more strongly induced by Escherichia coli (gram-negative) than by Micrococus luteus (gram-positive), and not by virus injection. By bacterial challenge, expression of BmCec-E mRNA was induced 12 h after injection, and was maintained for 24 h. Expression of BmCec-E after immune challenge was observed strongly in excretory organs, such as hindgut and malphigian, slightly in fat body, skin, and midgut.