Thoracic Outlet Syndrome Secondary to Vascular Insufficiency from Congenital Pseudarthrosis of the Clavicle: A Case Report.

CASE: An 18-year-old woman with a history of congenital pseudarthrosis of the clavicle (CPC) presented with episodes of right upper extremity ischemia. Vascular studies demonstrated an extensive thrombus with complete occlusion of the brachial artery. She underwent urgent thrombectomy. Subsequently, she underwent first rib resection and scalenectomy as well as pseudarthrosis takedown and fixation. Postoperatively, she returned to Division I collegiate soccer with complete symptomatic resolution. CONCLUSION: We report a case of arterial thoracic outlet syndrome secondary to CPC.

The Starfish Procedure for Independent Digital Control of a Myoelectric Prosthesis.

Management of partial hand amputations is a notable clinical challenge. Historically, myoelectric prostheses have not allowed for independent digital control, resulting in unsatisfactory function and high rejection rates among upper extremity amputees. The Starfish Procedure was developed for patients who sustained loss of multiple digits through the level of the base of the proximal phalanx or distal metacarpal. The procedure involves the pedicled transfer of 1 or more dorsal interosseous muscles to a subcutaneous location. This allows for a myoelectric sensor to capture the signals generated by these transferred muscles, thereby enabling intuitive, independent, digital prosthetic flexion and extension. In this article, we detail the relevant anatomy, indications, and technique for performing the Starfish Procedure. Given our patients' promising outcomes to date, we hope this technique paper will encourage upper extremity surgeons of all training backgrounds to perform this relatively straightforward procedure, thereby allowing patients with life-altering finger amputations to regain meaningful function by enhancing control of digital prostheses.

The Impact of Certificate of Need Status on the Utilization and Reimbursement of Open and Endoscopic Carpal Tunnel Release.

A certificate of need (CON) permits a healthcare organization to build new facilities only if significant medical needs exist. Many states have implemented CON programs to prevent procedure overutilization and price inflation. We hypothesized that there are no differences in reimbursement or utilization for open and endoscopic carpal tunnel release (CTR) when comparing states with and without CON programs. We queried a private-payer database to identify open and endoscopic CTRs performed between 2007 and 2015. In total, 82,689 CTRs were identified: 70,160 open, 12,529 endoscopic. Reimbursement increased for open procedures (compound annual growth rate [CAGR] 1.0% CON, 1.4% non-CON) but only marginally increased or decreased in the endoscopic group (CAGR -0.8% CON, 0.2% non-CON). Utilization increased across all settings, and was highest in the endoscopic CON group (CAGR 17.9%). Least growth was seen in the open non-CON group (CAGR 10.0%). Overall, CON programs may not actually decrease CTR spending or utilization. (Journal of Surgical Orthopaedic Advances 30(2):090-092, 2021).

Rod-Screw Constructs Composed of Dissimilar Metals Do Not Affect Complication Rates in Posterior Fusion Surgery Performed for Adult Spinal Deformity.

STUDY DESIGN: This was a retrospective cohort study. OBJECTIVE: The objective of this study was to compare implant-related complications between mixed-metal and same-metal rod-screw constructs in patients who underwent posterior fusion for adult spinal deformity. SUMMARY OF BACKGROUND DATA: Contact between dissimilar metals is discouraged due to potential for galvanic corrosion, increasing the risk for metal toxicity, infection, and implant failure. In spine surgery, titanium (Ti) screws are most commonly used, but Ti rods are notch sensitive and likely more susceptible to fracture after contouring for deformity constructs. Cobalt chrome (CC) and stainless steel (SS) rods may be suitable alternatives. No studies have yet evaluated implant-related complications among mixed-metal constructs (SS or CC rods with Ti screws). METHODS: Adults with spinal deformity who underwent at least 5-level thoracic and/or lumbar posterior fusion or 3-column osteotomy between January 2013 and May 2015 were reviewed, excluding neuromuscular deformity, tumor, acute trauma or infection. Implant-related complications included pseudarthrosis, proximal junctional kyphosis, hardware failure (rod fracture, screw pullout or haloing), symptomatic hardware, and infection. RESULTS: A total of 61 cases met inclusion criteria: 24 patients received Ti rods with Ti screws (Ti-Ti, 39%), 31 SS rods (SS-Ti, 51%), and 6 CC rods (CC-Ti, 9.8%). Median follow-up was 37-42 months for all groups. Because of the limited number of cases, the CC-Ti group was not included in statistical analyses. There were no differences between Ti-Ti and SS-Ti groups with regard to age, body mass index, or smokers. Implant-related complications did not differ between the Ti-Ti and SS-Ti groups (P=0.080). Among the Ti-Ti group, there were 15 implant-related complications (63%). In the SS-Ti group, there were 12 implant-related complications (39%). There were 3 implant-related complications in the CC-Ti group (50%). CONCLUSION: We found no evidence that combining Ti screws with SS rods increases the risk for implant-related complications.

Use of Navigation-Enhanced Instrumentation to Mitigate Surgical Outliers During Total Knee Arthroplasty.

Computer-assisted orthopedic surgery improves mechanical alignment and the accuracy of surgical cuts in the context of total knee arthroplasty (TKA). A simplified, navigation-enhanced instrumentation system was assessed to determine whether the same effects could be achieved with a less intrusive system. Two cohorts of surgeons (experienced and trainees) performed a series of TKA cuts using models with and without navigation-enhanced instrumentation. The accuracy of each system was determined via the rate of outliers, measured as any cut that deviated from the planned cut by more than 2° or 2 mm. The effect of experience level was limited, with only the outlier rate for tibial varus or valgus measurement showing a significant difference between user groups with conventional instrumentation (P=.004). The use of navigation-enhanced instrumentation significantly reduced the total outlier rate compared with conventional instrumentation from 35% to 4% for experienced users (P<.001) and from 34% to 10% for trainees (P<.001). These results suggest that navigation-enhanced instrumentation is a viable alternative to conventional instrumentation to reduce outlier rates and improve cut accuracy. This trial also showed that additional experience may not correlate with improved surgical accuracy. Outliers may not reflect individual surgical ability as much as limitations of the instrumentation or other unidentified factors. [Orthopedics. 2021;44(1):54-57.].

Cannabinoid and Opioid Use Among Total Joint Arthroplasty Patients: A 6-Year, Single-Institution Study.

Evidence is limited regarding cannabinoid use among total joint arthroplasty (TJA) patients, despite increased availability and popularity for treating chronic pain. The authors hypothesized that preoperative cannabinoid use increased and opioid use decreased during a 6-year interval in total hip arthroplasty (THA) and total knee arthroplasty (TKA) patients, and also asked whether complications were associated with use of these substances. This retrospective, single-institution study reviewed electronic medical records and the Veterans Affairs Surgical Quality Improvement Program (VASQIP) database for TJA cases from 2012 through 2017. Primary outcomes were the prevalence and trends of active cannabinoid and opioid use, as determined by routine preoperative urine toxicology screening. Multivariable regression analyses were conducted to investigate a secondary outcome, whether there was an association between cannabinoid or opioid use and postoperative complications. A total of 1778 operations (1161 TKAs and 617 THAs) performed on 1519 patients were reviewed. The overall prevalence of pre-operative cannabinoid and opioid use was 11% and 23%, respectively. Comparing 2012 with 2017, cannabinoid use increased from 9% to 15% (P=.049), and opioid use decreased from 24% to 17% (P=.040). Cannabinoid users were more likely to be taking opioids than nonusers (P=.002). Controlling for age, sex, surgery type, and American Society of Anesthesiologists score, cannabinoid use was not associated with 90-day readmission, infection, reoperation, or other VASQIP-captured complications. Laboratory testing indicated a much higher prevalence of cannabinoid use among TJA patients than previously reported. During a 6-year period, cannabinoid use increased more than 60%, and opioid use decreased approximately 30%. These findings indicate that cannabinoid use did not appear to be associated with perioperative complications. [Orthopedics. 2021;44(1):e101-e106.].

Bilateral Medial Patella Sleeve Fractures in a Child: A Case Report.

CASE: An 8-year-old girl presented with a displaced right medial patella sleeve fracture. She underwent open reduction and suture fixation. Three years later, she presented with a left medial patella sleeve fracture that was less displaced than on the right. This was treated with immobilization and structured rehabilitation. She was able to return to full activity with normal radiographs at the final follow-up. CONCLUSION: Patella sleeve fractures are rare. We report a unique case of bilateral medial patella sleeve fractures in an otherwise healthy child in which one side was treated operatively and the other was treated nonoperatively.

Preoperative Exercise Participation Reflects Patient Engagement and Predicts Earlier Patient Discharge and Less Gait Aid Dependence After Total Joint Arthroplasty.

Whether preoperative physical therapy actually leads to improved clinical outcomes after total joint arthroplasty (TJA) remains unclear. The authors sought to use participation in a preoperative online exercise and education program as a marker for patient engagement. They hypothesized that increased preoperative participation with the program would predict shorter length of stay (LOS) and gait independence. Forty consecutive patients undergoing primary total hip arthroplasty (THA) or total knee arthroplasty (TKA) by a single surgeon were given access to the PrimePrehab Prehabilitation Exercise Program (NextPT, Boulder, Colorado). Patients were guided through questionnaires, and the program generated educational readings and exercise modules directed toward initial ability. Preoperative completion of readings, completion of exercise modules, and improvement in exercise difficulty were tracked. Patients received a standardized postoperative protocol, including physical therapy on the day of surgery and subsequent hospital days. Length of stay and gait aid use at 90 days postoperatively were recorded. Analyses were simple or multiple regression with a significance of P≤.05. Patients completed a mean of 7 exercise modules with 30% improvement in difficulty. Controlling for demographic variables, the frequency of program completion correlated with shorter LOS (P=.037). This finding was not different between THA and TKA (P=.387). No association was found between the frequency of program completion and gait aid use at 90 days (P=.213), although there was a decrease in gait aid use at 90 days with improvement in exercise difficulty (P=.034). A preoperative education and exercise program can predict patient engagement, which correlates with a shorter LOS and suggests that increasing exercise difficulty is associated with gait independence after TJA. [Orthopedics. 2020;43(5):e364-e368.].

Reimbursement and Complications in Outpatient vs Inpatient Unicompartmental Arthroplasty.

BACKGROUND: Increasing utilization of unicompartmental knee arthroplasty (UKA) has driven a greater push for outpatient treatment and cost containment in the setting of bundled payments. The purpose of this study is to evaluate utilization trends of inpatient vs outpatient UKA, index episode and 90-day reimbursement, and any differences in medical or surgical complications. METHODS: The PearlDiver database was employed to identify all inpatient and outpatient UKAs performed between 2007 and 2016 with 2-year follow-up. Patients were matched by age, gender, and Elixhauser Comorbidity Index. We tracked index procedure and global period reimbursement, 90-day medical and surgical complications, and 2-year surgical complications. RESULTS: The reimbursement and utilization cohort included 3181 outpatient and 5490 inpatient UKAs. Outpatient UKA and overall utilization of UKA increased over the study period. Mean index reimbursement of inpatient UKA was $2486.16 higher per procedure (P < .001) while mean global period reimbursement was $2782.13 higher per inpatient procedure (P < .001). Ninety-day medical complications including postoperative anemia (P < .001), transfusion (P = .024), and arrhythmia (P = .004) were more common with inpatient UKAs, whereas surgical wound complications (P = .001) and operative debridement (P = .028) were more common among outpatient UKAs. Outpatient UKA was not associated with an increased risk of periprosthetic joint infection (P > .05), aseptic loosening (P > .05), or revision surgery (P > .05) when compared to inpatient UKA. CONCLUSION: Outpatient UKA utilization is increasing and is associated with decreased reimbursement compared to inpatient UKA without increased risk of major medical complications, although it is associated with increased risk of wound complication and need for operative debridement at 90 days.

Postoperative continuous adductor canal block for total knee arthroplasty improves pain and functional recovery: A randomized controlled clinical trial.

STUDY OBJECTIVE: Investigate the use of a postoperative continuous adductor canal block (cACB) after epidural analgesia to decreases opioid consumption and improve visual analog scale (VAS) scores compared to a sham catheter. DESIGN: Double-blinded randomized placebo-controlled trial. SETTING: Inpatient setting in tertiary care teaching hospital with outpatient follow-up. PATIENTS: One-hundred and sixty-five subjects (cACB n = 82 and sham catheter n = 83) with end-stage degenerative joint disease undergoing elective unilateral total knee arthroplasty. INTERVENTIONS: Patients were block randomized to receive a cACB or sham catheter. An epidural catheter was placed preoperatively and discontinued on postoperative day 1. Patients then received a cACB with bupivacaine or sham catheter which remained for the duration of the hospitalization. MEASUREMENTS: Primary outcome was total opioid consumption. Secondary outcomes included VAS scores, knee range of motion (ROM), ambulation distance, and WOMAC scores. MAIN RESULTS: Seventy patients completed the study (cACB n = 38 and sham catheter n = 32). Compared to sham catheter, in the first 20 h after placement of a cACB, patients used 22.5 mg less opioid (95% CI: -43.1 to -1.94 mg, P = 0.03). VAS score area under the curve decreased 7.8 mm (95% CI: -15.5 - -0.058 mm, P = 0.04) with a cACB. At 3-week follow-up, WOMAC scores were significantly improved with the cACB with a mean difference of 8.72 (95% CI: -17.3 to -0.11, P = 0.04). There were no statistically significant differences in secondary outcomes on postoperative day 2. Paired outcomes at 6 weeks compared to baseline ROM, showed significant improvement in knee ROM with a cACB (mean difference 11.77°, 95% CI: 3.1-20.5°, P = 0.01). CONCLUSION: A postoperative cACB after total knee arthroplasty significantly reduces total opioid consumption and pain scores compared to sham catheter. Ambulatory ability was not affected and patients recovered function earlier. ClinicalTrials.govNCT02121392.

Immortalized Mouse Achilles Tenocytes Demonstrate Long-Term Proliferative Capacity While Retaining Tenogenic Properties.

Investigating the cellular processes underlying tendon healing can allow researchers to improve long-term outcomes after injury. However, conducting meaningful studies to uncover the injury healing mechanism at cellular and molecular levels remains challenging. This is due to the inherent difficulty in isolating, culturing, and expanding sufficient primary tenocytes, due to their limited proliferative capacity and short lifespan. In this study, we sought to establish a novel line of immortalized mouse Achilles tenocytes (iMATs) with primary tenocyte properties, but increased proliferative capacity suitable for extensive in vitro experimentation. We show that isolated primary mouse Achilles tenocytes (pMATs) can be effectively immortalized using a piggyBac transposon expressing SV40 large T antigen flanked by FLP recombination target site (FRT). The resulting iMATs exhibit markedly greater proliferation and survival, which can be reversed with FLP recombinase. Furthermore, iMATs express the same set of tendon-specific markers as that of primary cells, although in lower levels, and respond similarly to exogenous stimulation with bone morphogenetic protein 13 (BMP13) as has been previously reported with pMATs. Taken together, our results suggest that iMATs acquire long-term proliferative capacity while maintaining tenogenic properties. We believe that iMATs are a suitable model for studying not only the native cellular processes involved in injury and healing, but also potential therapeutic agents that may augment the stability of tendon repair.

Effect of Obesity on Total Ankle Arthroplasty Outcomes.

BACKGROUND: The purpose of this study was to evaluate the effect of obesity on intermediate- to long-term implant failure rates and survivorship after total ankle arthroplasty. METHODS: A chart review was performed for all patients who underwent primary total ankle arthroplasty between 2004 and 2009 with a minimum 5-year follow-up. Patients were separated into a reference group with a body mass index less than 30 kg/m2 and an obese group with an index greater than or equal to 30 kg/m2. Minimum 5-year follow-up outcomes were available for 49 patients in the obese group and 48 patients in the nonobese group. Mean follow-up was 8.2 ± 2.0 years (range, 5.1-11.5 years) in the reference group and 7.7 ± 2.0 years (range, 5.0-11.9 years) in the obese group (P = .26). RESULTS: Based on multivariable logistic regression, obese patients had a significantly greater probability of implant failure by final follow-up (adjusted odds ratio, 2.8 [95% CI, 1.04-7.53]; P = .04). Cox regression analysis of 5-year implant survivorship showed no significant difference between the 2 groups (adjusted hazard ratio, 1.89 [95% CI, 0.77-4.65]; P = .17). When compared with obese patients with inflammatory or posttraumatic arthritis, obese patients with osteoarthritis demonstrated a significantly decreased 5-year survivorship (adjusted hazard ratio, 3.73 [95% CI, 1.05-10.43]; P = .04). CONCLUSION: This study demonstrated an increased long-term risk of implant failure among obese patients that was not seen in the intermediate term. Furthermore, obese patients with primary osteoarthritis were found to have a significantly decreased 5-year implant survivorship after ankle arthroplasty as compared with obese patients with inflammatory or posttraumatic arthritis and therefore should be counseled appropriately when deciding between arthroplasty and arthrodesis. LEVEL OF EVIDENCE: Level III, retrospective comparative series.

Development of genu valgum after removal of osteochondromas from the proximal tibia.

Genu valgum is a well-documented deformity secondary to hereditary multiple exostoses about the knee. Post-traumatic tibia valgus is also a well-described phenomenon that occurs in children who sustain an incomplete fracture of the proximal tibia. The finding is considered to be secondary to asymmetric blood flow to the proximal tibial physis. The existing literature only describes genu valgum as a sequela of the hereditary multiple exostoses disorder itself and does not address genu valgum occurring as a postoperative consequence of mass excision. In this paper, we report on three pediatric patients who developed unilateral genu valgum after removal of osteochondromas from the medial proximal tibia. Chart and radiographic data were retrospectively reviewed for a series of three patients. Three patients developed genu valgum after medial proximal tibial osteochondroma excision. The maximum tibiofemoral angle varied from 17 to 23°. One case resolved spontaneously with observation, one was addressed surgically with guided growth correction, and another was advised to undergo operative correction, but declined. We conclude that genu valgum can arise secondary to osteochondroma excision when the mass is resected near the proximal tibial physis. Surgeons should counsel patients on the possibility of postoperative angular growth deformity and monitor closely for its development.

A Novel Organ Culture Model of Mouse Intervertebral Disc Tissues.

The intervertebral disc (IVD) is a fibrocartilaginous joint between two vertebral bodies. An IVD unit consists of a gelatinous central nucleus pulposus, encased by the annulus fibrosus, which is sandwiched between cartilaginous endplates (EPs). The IVD homeostasis can be disrupted by injuries, ageing and/or genetic predispositions, leading to degenerative disc disorders and subsequent lower back pain. The complex structure and distinct characteristics of IVDs warrant the establishment of robust in vitro IVD organ culture for studying the etiology and treatment of disc degeneration. Here, we isolate mouse lumbar IVDs and culture the minimal IVD units in submersion or suspension medium supplemented with 2% bovine serum or 10% fetal bovine serum (FBS). We find the minimal IVD units remain healthy for up to 14 days when cultured in submersion culture supplemented with 10% FBS. New bone formation in the EPs of the cultured IVDs can be assessed with calcein labeling. Furthermore, the cultured IVDs can be effectively transduced by recombinant adenovirus, and transgene expression lasts for 2 weeks. Thus, our findings demonstrate that the optimized IVD organ culture system can be used to study IVD biology and screen for biological factors that may prevent, alleviate and/or treat disc degeneration.

Molecular pathogenesis and therapeutic strategies of human osteosarcoma.

Osteosarcoma (OS) is a devastating illness with rapid rates of dissemination and a poor overall prognosis, despite aggressive standard-of-care surgical techniques and combination chemotherapy regimens. Identifying the molecular mechanisms involved in disease pathogenesis and progression may offer insight into new therapeutic targets. Defects in mesenchymal stem cell differentiation, abnormal expression of oncogenes and tumor suppressors, and dysregulation within various important signaling pathways have all been implicated in development of various disease phenotypes. As such, a variety of basic science and translational studies have shown promise in identifying novel markers and modulators of these disease-specific aberrancies. Born out of these and similar investigations, a variety of emerging therapies are now undergoing various phases of OS clinical testing. They broadly include angiogenesis inhibitors, drugs that act on the bone microenvironment, receptor tyrosine kinase inhibitors, immune system modulators, and other radio- or chemo-sensitizing agents. As new forms of drug delivery are being developed simultaneously, the possibility of targeting tumors locallywhile minimizing systemic toxicityis is seemingly more achievable now than ever. In this review, we not only summarize our current understanding of OS disease processes, but also shed light on the multitude of potential therapeutic strategies the scientific community can use to make long-term improvements in patient prognosis.

Insider information: Testing cancer drug sensitivity for personalized therapy.

Cancer death is usually caused by incurable drug-resistant and metastatic cancers. Although tremendous progress has been made in anticancer drug development during the past two decades, cancer medicine still faces unprecedented challenges associated with choosing effective treatments for individual patients. Three recent reports have offered encouraging approaches towards potentially personalized cancer drug selection.

TqPCR: A Touchdown qPCR Assay with Significantly Improved Detection Sensitivity and Amplification Efficiency of SYBR Green qPCR.

The advent of fluorescence-based quantitative real-time PCR (qPCR) has revolutionized the quantification of gene expression analysis in many fields, including life sciences, agriculture, forensic science, molecular diagnostics, and medicine. While SYBR Green-based qPCR is the most commonly-used platform due to its inexpensive nature and robust chemistry, quantifying the expression of genes with low abundance or RNA samples extracted from highly restricted or limited sources can be challenging because the detection sensitivity of SYBR Green-based qPCR is limited. Here, we develop a novel and effective touchdown qPCR (TqPCR) protocol by incorporating a 4-cycle touchdown stage prior to the quantification amplification stage. Using the same cDNA templates, we find that TqPCR can reduce the average Cq values for Gapdh, Rps13, and Hprt1 reference genes by 4.45, 5.47, and 4.94 cycles, respectively, when compared with conventional qPCR; the overall average Cq value reduction for the three reference genes together is 4.95. We further find that TqPCR can improve PCR amplification efficiency and thus increase detection sensitivity. When the quantification of Wnt3A-induced target gene expression in mesenchymal stem cells is analyzed, we find that, while both conventional qPCR and TqPCR can detect the up-regulation of the relatively abundant target Axin2, only TqPCR can detect the up-regulation of the lowly-expressed targets Oct4 and Gbx2. Finally, we demonstrate that the MRQ2 and MRQ3 primer pairs derived from mouse reference gene Tbp can be used to validate the RNA/cDNA integrity of qPCR samples. Taken together, our results strongly suggest that TqPCR may increase detection sensitivity and PCR amplification efficiency. Overall, TqPCR should be advantageous over conventional qPCR in expression quantification, especially when the transcripts of interest are lowly expressed, and/or the availability of total RNA is highly restricted or limited.

Insulin-like growth factor (IGF) signaling in tumorigenesis and the development of cancer drug resistance.

One of the greatest obstacles to current cancer treatment efforts is the development of drug resistance by tumors. Despite recent advances in diagnostic practices and surgical interventions, many neoplasms demonstrate poor response to adjuvant or neoadjuvant radiation and chemotherapy. As a result, the prognosis for many patients afflicted with these aggressive cancers remains bleak. The insulin-like growth factor (IGF) signaling axis has been shown to play critical role in the development and progression of various tumors. Many basic science and translational studies have shown that IGF pathway modulators can have promising effects when used to treat various malignancies. There also exists a substantial body of recent evidence implicating IGF signaling dysregulation in the dwindling response of tumors to current standard-of-care therapy. By better understanding both the IGF-dependent and -independent mechanisms by which pathway members can influence drug sensitivity, we can eventually aim to use modulators of IGF signaling to augment the effects of current therapy. This review summarizes and synthesizes numerous recent investigations looking at the role of the IGF pathway in drug resistance. We offer a brief overview of IGF signaling and its general role in neoplasia, and then delve into detail about the many types of human cancer that have been shown to have IGF pathway involvement in resistance and/or sensitization to therapy. Ultimately, our hope is that such a compilation of evidence will compel investigators to carry out much needed studies looking at combination treatment with IGF signaling modulators to overcome current therapy resistance.

Sustained high level transgene expression in mammalian cells mediated by the optimized piggyBac transposon system.

Sustained, high level transgene expression in mammalian cells, especially stem cells, may be desired in many cases for studying gene functions. Traditionally, stable transgene expression has been accomplished by using retroviral or lentiviral vectors. However, such viral vector-mediated transgene expression is often at low levels and can be reduced over time due to low copy numbers and/or chromatin remodeling repression. The piggyBac transposon has emerged as a promising non-viral vector system for efficient gene transfer into mammalian cells. Despite its inherent advantages over lentiviral and retroviral systems, piggyBac system has not been widely used, at least in part due to the limited availability of piggyBac vectors with manipulation flexibilities. Here, we seek to optimize piggyBac-mediated transgene expression and generate a more efficient, user-friendly piggyBac system. By engineering a panel of versatile piggyBac vectors and constructing recombinant adenoviruses expressing piggyBac transposase (PBase), we demonstrate that adenovirus-mediated PBase expression significantly enhances the integration efficiency and expression level of transgenes in mesenchymal stem cells and osteosarcoma cells, compared to that obtained from co-transfection of the CMV-PBase plasmid. We further determine the drug selection timeline to achieve optimal stable transgene expression. Moreover, we demonstrate that the transgene copy number of piggyBac-mediated integration is approximately 10 times higher than that mediated by retroviral vectors. Using the engineered tandem expression vector, we show that three transgenes can be simultaneously expressed in a single vector with high efficiency. Thus, these results strongly suggest that the optimized piggyBac system is a valuable tool for making stable cell lines with sustained, high transgene expression.