Bio

Clinical Focus


  • Residency

Professional Education


  • MD, Duke University, Medicine. Alpha Omega Alpha. (2016)
  • BA, University of California, Berkeley, Molecular and Cell Biology, Emphasis Biochemistry and Molecular Biology. Phi Beta Kappa. Honors. Summa Cum Laude (2012)

Publications

All Publications


  • Venous Thromboembolism Prophylaxis After TKA: Aspirin, Warfarin, Enoxaparin, or Factor Xa Inhibitors? Clinical orthopaedics and related research Bala, A., Huddleston, J. I., Goodman, S. B., Maloney, W. J., Amanatullah, D. F. 2017

    Abstract

    There is considerable debate regarding the ideal agent for venous thromboembolism (VTE) prophylaxis after TKA. Numerous studies and meta-analyses have yet to provide a clear answer and often omit one or more of the commonly used agents such as aspirin, warfarin, enoxaparin, and factor Xa inhibitors.Using a large database analysis, we asked: (1) What are the differences in VTE incidence in primary TKA after administration of aspirin, warfarin, enoxaparin, or factor Xa inhibitors? (2) What are the differences in bleeding risk among these four agents? (3) How has use of these agents changed with time?We queried a combined Humana and Medicare database between 2007 and Quarter 1 of 2016, and identified all primary TKAs performed using ICD-9 and Current Procedural Terminology codes. All patients who had any form of antiplatelet or anticoagulation prescribed within 1 year before TKA were excluded from our study cohort. We then identified patients who had either aspirin, warfarin, enoxaparin, or factor Xa inhibitors prescribed within 2 weeks of primary TKA. Each cohort was matched by age and sex. Elixhauser comorbidities and Charlson Comorbidity Index for each group were calculated. We identified 1016 patients with aspirin, and age- and sex-matched 6096 patients with enoxaparin, 6096 patients with warfarin, and 5080 patients with factor Xa inhibitors. Using ICD-9 codes, with the understanding that patients at greater risk may have had more-attentive surveillance, the incidence of postoperative deep venous thrombosis (DVT), pulmonary embolism (PE), bleeding-related complications (bleeding requiring surgical intervention, hemorrhage, hematoma, hemarthrosis), postoperative anemia, and transfusion were identified at 2 weeks, 30 days, 6 weeks, and 90 days postoperatively. A four-way chi-squared test was used to determine statistical significance. Utilization was calculated using compound annual growth rate.There was a difference in the incidence of DVT at 90 days (p < 0.01). Factor Xa inhibitors (2.9%) had the lowest incidence of DVT followed by aspirin (3.0%) and enoxaparin (3.5%), and warfarin (4.8%). There was a difference in the incidence of PE at 90 days (p < 0.01). Factor Xa inhibitors (0.9%) had the lowest incidence of PE followed by enoxaparin (1.1%), aspirin (1.2%), and warfarin (1.6%). There was a difference in the incidence of postoperative anemia at 90 days (p < 0.01). Aspirin (19%) had the lowest incidence of postoperative anemia followed by warfarin (22%), enoxaparin (23%), and factor Xa inhibitors (23%). There was a difference in the incidence of a blood transfusion at 90 days (p < 0.01). Aspirin (7%) had the lowest incidence of a blood transfusion followed by factor Xa inhibitors (9%), warfarin (12%), and enoxaparin (13%). There were no differences in bleeding-related complications (p = 0.81) between the groups. Aspirin use increased at a compound annual growth rate of 30%, enoxaparin at 3%, and factor Xa inhibitors at 43%, while warfarin use decreased at a compound annual growth rate of -3%.Factor Xa inhibitors had the highest growth in utilization during our study period, followed by aspirin, when compared with enoxaparin and warfarin. When selected for the right patient, factor Xa inhibitors provided improved VTE prophylaxis compared with enoxaparin and warfarin, with a lower rate of blood transfusion. Aspirin provided comparable VTE prophylaxis compared with factor Xa inhibitors with improved VTE prophylaxis compared with enoxaparin and warfarin with the lowest risk of bleeding.Level III, therapeutic study.

    View details for DOI 10.1007/s11999-017-5394-6

    View details for PubMedID 28569372

  • Complications of total hip arthroplasty following solid organ transplantation. Journal of orthopaedic science Klement, M. R., Penrose, C. T., Bala, A., Green, C. L., Mather, R. C., Wellman, S. S., Bolognesi, M. P., Seyler, T. M. 2017; 22 (2): 295-299

    Abstract

    Solid organ transplants (SOT) continue to increase with recipients living longer than ever before. The lifelong immunosuppression in these patients also may place them at increased risk for postoperative complications. The efficacy of total hip arthroplasty (THA) in this patient population is undisputed but previous studies investigating the complication profiles in these patients often are underpowered to identify rare complications as well as make comparisons between individual organs. The purpose of this study was to use a large database to compare complications of a combined SOT cohort as well as each individual organ to a control population.A search of the entire Medicare database from 2005 to 2011 was performed using International Classification of Disease version 9 (ICD-9) codes to identify patients who underwent THA after one or more solid organ transplants. A large cohort of patients served as a control with minimum 2-year follow-up. Post-operative complications at 30-day, 90-day, and overall time points were investigated.Transplant patients carry more medical comorbidities and are prone to increased medical complications, dislocations (OR 1.45, p < 0.001), need for irrigation and debridement (OR 1.90, p < 0.001), and periprosthetic infection (OR 1.69, p < 0.001) compared to patients without SOT. Total hip arthroplasty after renal transplantation has the worst complication profile of the individual organs whereas lung and pancreas transplants were no different than control with regard to overall surgical complications.The complications of THA after SOT vary by individual organ and these results may aid in patient selection and perioperative patient counseling.

    View details for DOI 10.1016/j.jos.2016.12.004

    View details for PubMedID 28027829

  • Analysis of complication rates following perioperative transfusion in shoulder arthroplasty. Journal of shoulder and elbow surgery Grier, A. J., Bala, A., Penrose, C. T., Seyler, T. M., Bolognesi, M. P., Garrigues, G. E. 2017

    Abstract

    Postoperative anemia requiring a blood transfusion is not uncommon following anatomic total shoulder arthroplasty (TSA) or reverse total shoulder arthroplasty (RTSA). However, the potential complications in patients undergoing transfusion after shoulder arthroplasty remain unclear. The goal of this study was to examine the postoperative outcomes of patients receiving blood transfusions following TSA and RTSA.Using the Medicare Standard Analytic Files database, we identified all patients undergoing TSA or RTSA between 2005 and 2010. Using International Classification of Diseases, Ninth Revision, Clinical Modification and Current Procedural Terminology codes, we identified the procedure, transfusion status, comorbidities, and postoperative complications of interest. Odds ratios and 95% confidence intervals were calculated.We identified 7,794 patients who received a perioperative blood transfusion following TSA or RTSA, as well as 34,293 age- and gender-matched controls, during the study period. Patients who received a perioperative transfusion had statistically significantly higher rates of myocardial infarction, pneumonia, systemic inflammatory response syndrome or sepsis, venous thromboembolic events, and cerebrovascular accidents at all time points in question. Patients who received a blood transfusion also showed an increased incidence of surgical complications, including periprosthetic infection and mechanical complications, up to 2 years postoperatively.To our knowledge, this represents the largest study to examine the relationship between the need for perioperative blood transfusion and postoperative medical and surgical outcomes following TSA and RTSA. The results observed in this study highlight the importance of preoperative counseling and medical optimization prior to shoulder arthroplasty, particularly in patients with preoperative anemia or multiple medical comorbidities.

    View details for DOI 10.1016/j.jse.2016.11.039

    View details for PubMedID 28153684

  • Glenohumeral arthritis as a risk factor for proximal humerus nonunion INJURY-INTERNATIONAL JOURNAL OF THE CARE OF THE INJURED Klement, M. R., Nickel, B. T., Bala, A., Penrose, C. T., Zura, R. D., Garrigues, G. E. 2016; 47: S36-S39

    Abstract

    Proximal humerus fractures are common injuries and nonsurgical treatment has proven to yield good to excellent clinical results. A small percentage of these fractures go on to delayed or nonunion and the incidence and risk factors for this complication are poorly understood. We hypothesize that adjacent joint stiffness of the glenohumeral joint might lead to an increased rate of nonunion for proximal humerus fractures.A search of the entire Medicare database from 2005 to 2011 was performed to identify 38,754 patients who sustained a proximal humerus fracture including 13,802 with co-existing ipsilateral shoulder osteoarthritis (OA) and 24,952 with co-existing diagnosis of rheumatoid arthritis (RA). A cohort of 301,987 patients served as a control. Medical co-morbidities and fracture complications were compared between the cohorts.The incidence of delayed union at 3 and 6 months for OA and RA groups were significantly increased compared to control at 0.79% and 1.74%, and 0.67% and 1.86%, respectively (p < 0.001). Nonunion rates were also significantly increased (p < 0.001) in the OA and RA cohorts at 9 months and 1 year with incidences of 2.39%, 2.89% and 2.59% and 3.08%, Respectively. The incidence of nonunion in the control cohort at the same time points was 1.13% and 1.35%.The coexistence of shoulder OA or a diagnosis of RA nearly doubled in the incidence of proximal humerus nonunion. This is the first study investigating this association in the shoulder and should be considered along with traditional nonunion risk factors in the treatment algorithm.

    View details for Web of Science ID 000395193100009

    View details for PubMedID 28040076

  • Total shoulder arthroplasty in patients with HIV infection: complications, comorbidities, and trends JOURNAL OF SHOULDER AND ELBOW SURGERY Bala, A., Penrose, C. T., Visgauss, J. D., Seyler, T. M., Randell, T. R., Bolognesi, M. P., Garrigues, G. E. 2016; 25 (12): 1971-1979

    Abstract

    Patients with human immunodeficiency virus (HIV) infection were previously at substantial risk for immunosuppression-related complications. As a result of highly active antiretroviral therapy, HIV-infected patients are living longer and are presenting for elective surgery. Outcomes in HIV-infected patients are well described for hip and knee arthroplasty but not for total shoulder arthroplasty (TSA). The purpose of this study was to examine postoperative complications of TSA in HIV-positive patients.We queried the entire 2005 to 2012 Medicare database. Current Procedural Terminology and International Classification of Diseases, Ninth Revision, Clinical Modification codes were used to identify the procedure, demographics, comorbidities, and postoperative complications. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated.The query returned 2528 HIV-positive patients who underwent TSA or reverse TSA (RTSA). There was increased utilization of TSA and RTSA in this population from 2005 to 2012; 1353 patients had 2-year follow-up. These patients were slightly older and had higher prevalence of comorbidities, suggesting a sicker cohort. HIV-positive patients had alarmingly higher rates of 90-day cerebrovascular accident (OR, 35.98; CI, 30.34-42.67). HIV-positive patients had higher overall rates of broken prosthetic joints (OR, 1.72; CI, 1.20-2.47), periprosthetic infection (OR, 1.36; CI, 1.01-1.82), and TSA revision or repair (OR, 2.44; CI, 1.81-3.28).To our knowledge, this is the first study that directly examines the postoperative outcomes of HIV-positive patients after TSA or RTSA. As more of these patients present for surgery, surgeons should be aware that these patients might be at increased risk for certain postoperative surgical and medical complications.

    View details for DOI 10.1016/j.jse.2016.02.033

    View details for Web of Science ID 000389699100014

    View details for PubMedID 27117043

  • Psychiatric disorders increase complication rate after primary total knee arthroplasty KNEE Klement, M. R., Nickel, B. T., Penrose, C. T., Bala, A., Green, C. L., Wellman, S. S., Bolognesi, M. P., Seyler, T. M. 2016; 23 (5): 883-886

    Abstract

    Psychiatric disease is difficult to screen preoperatively and the incidence of mental health disorders in patients undergoing total knee arthroplasty (TKA) may be underappreciated. The purpose of this study is to evaluate the perioperative complication profile in patients with psychiatric disorders.A search of the entire Medicare database from 2005 to 2011 was performed to identify patients who underwent primary TKA with bipolar disorder (20,972), depression (187,448), and schizophrenia (7607). A cohort of 1,271,464 patients as controls with minimum 2.5-year follow-up. Medial and surgical complications at 30-days, 90-days, and overall were compared between the two cohorts.Patients with any psychiatric disease were more likely to be younger (age<65 OR 5.5, p<0.001), female (OR 2.61, p<0.001), and more medically complex (significant increase in 28/28 Elixhauser medical comorbidities, p<0.05). There was a significant increase (p<0.001) in 11/14 (78.5%) of recorded postoperative medical complication rates at 90-days. There was a statistically significant increase in periprosthetic infection (OR 2.17 p<0.001), periprosthetic fracture (OR 2.40, p<0.001), revision TKA (OR 2.06, p<0.001), and extensor mechanism rupture (OR 2.41, p<0.001) at 90day and overall time points.Patients with psychiatric disorders who undergo elective primary TKA have significantly increased medical and surgical complication rates in the global period and short term follow-up. An ideal screening tool is yet to be determined and these patients need to be counseled appropriately regarding the increased complication rates before proceeding with TKA.

    View details for DOI 10.1016/j.knee.2016.05.007

    View details for Web of Science ID 000384867600023

    View details for PubMedID 27288068

  • Is Metal-On-Metal Total Hip Arthroplasty Associated With Neurotoxicity? journal of arthroplasty Bala, A., Penrose, C. T., Seyler, T. M., Randell, T. R., Wellman, S. S., Bolognesi, M. P. 2016; 31 (9): 233-236 e1

    Abstract

    Isolated case reports in the literature describe systemic neurologic side effects associated with metal-on-metal (MOM) bearing surfaces, yet the incidence of these effects have not been evaluated beyond individual cases. The purpose of this study was to compare new diagnoses of these side effects described in isolated cases in large patient cohorts of MOM vs metal on polyethylene (MOP).We queried the entire Medicare database from 2005 to 2012. Total hip arthroplasty (THA) and bearing surface were determined using International Classification of Diseases, 9th revision procedure codes. Patients with 5-year follow-up were selected. Using International Classification of Diseases, 9th revision codes, we identified new diagnoses of previously reported neurologic side effects: peripheral neuropathy, sensorineural hearing loss, visual impairment, paresthesias, tinnitus, and vertigo. Comorbidities and demographics were collected. Odds ratios, CIs, and P values were calculated.Overall, 29,483 MOM THAs and 23,587 age- and gender-matched MOP THAs were identified. The average Charlson Comorbidity Index was 5 for both groups. MOM and MOP patients had 26 of 30 identical prevalence of Elixhauser-measure comorbidities. There was no statistically significant difference in new diagnoses of any of the side effects at any time point between the 2 groups over 5 years.This study represents, to our knowledge, the first longitudinal analysis of systemic neurotoxicity after THA in a large cohort of patients. The results of our study suggest that on the large scale, neurologic side effects previously described do not occur as a common attributable complication. Rather, these cases may be due to individual patient hypersensitivity to metal ions.

    View details for DOI 10.1016/j.arth.2016.03.035

    View details for PubMedID 27118351

  • Should We Think Twice About Psychiatric Disease in Total Hip Arthroplasty? journal of arthroplasty Klement, M. R., Bala, A., Blizzard, D. J., Wellman, S. S., Bolognesi, M. P., Seyler, T. M. 2016; 31 (9): 221-226

    Abstract

    Psychiatric disease (PD) is common, and the effect on complications in total hip arthroplasty (THA) is poorly understood. The purpose of this study was to evaluate the medical and surgical postoperative complication profile in patients with PD, and we hypothesize that they will be significantly increased compared with control group.A search of the entire Medicare database from 2005 to 2011 was performed using International Classification of Disease version 9 codes to identify 86,976 patients who underwent primary THA with PD including bipolar (5626), depression (82,557), and schizophrenia (3776). A cohort of 590,689 served as a control with minimum 2-year follow-up. Medical and surgical complications at 30-day, 90-day, and overall time points were compared between the 2 cohorts.Patients with PD were more likely to be younger (age < 65 years; odds ratio [OR] = 4.51, P < .001), female (OR = 2.02, P < .001) and more medically complex (significant increase in 28/28 Elixhauser medical comorbidities, P < .001). There was a significant increase (P < .001) in 13/14 (92.8%) recorded postoperative medical complications rates at the 90-day time point. In addition, there was a statistically significant increase in periprosthetic infection (OR = 2.26, P < .001), periprosthetic fracture (OR = 2.09, P < .001), dislocation (OR = 2.30, P < .001), and THA revision (OR = 1.93, P < .001) at overall follow-up.Patients with PD who undergo elective primary THA have significantly increased medical and surgical complication rates in the global period and short-term follow-up, and these patients need to be counseled accordingly.

    View details for DOI 10.1016/j.arth.2016.01.063

    View details for PubMedID 27067760

  • Perioperative Dexamethasone Administration Does Not Increase the Incidence of Postoperative Infection in Total Hip and Knee Arthroplasty: A Retrospective Analysis JOURNAL OF ARTHROPLASTY Richardson, A. B., Bala, A., Wellman, S. S., Attarian, D. E., Bolognesi, M. P., Grant, S. A. 2016; 31 (8): 1784-1787

    Abstract

    Dexamethasone is frequently used for the treatment of postoperative nausea and vomiting and as an adjunct in multimodal postoperative analgesia after total joint arthroplasty; however, the incidence of periprosthetic joint infection (PJI) after the use of perioperative dexamethasone in total joint arthroplasty has yet to be fully elucidated.A retrospective chart review was conducted of all patients who underwent total hip or knee arthroplasty (N = 6294) between January 1, 2002 and January 31, 2014. The primary outcome was PJI requiring surgical intervention. Patients were subdivided into 2 cohorts; patients who received perioperative dexamethasone, a single 4- to 10-mg intravenous dose, as prophylaxis against postoperative nausea and vomiting (Dex group; N = 557) and those that did not receive perioperative dexamethasone (No Dex group; N = 5737). Secondary measures included timing of infection, culture data, and the type and number of subsequent procedures. Statistical analysis was performed using a chi-square or Fisher's exact test where appropriate.Seventy-four joints of the 6294 joints included in this analysis ultimately developed a PJI for an overall incidence of infection of 1.2%. Seven of the 557 joints (1.3%) in the Dex group developed a PJI; 67 of the 5737 joints (1.2%) in the No Dex group developed an infection. This difference was not significant (P = .8022). No significant difference in the timing of infection or the number of subsequent procedures was seen.A single intravenous perioperative dose of dexamethasone had no statistically significant difference in the rate of PJI after total hip or knee arthroplasty.

    View details for DOI 10.1016/j.arth.2016.01.028

    View details for Web of Science ID 000380258100034

    View details for PubMedID 26869066

  • Computer-Navigated Total Knee Arthroplasty Utilization JOURNAL OF KNEE SURGERY Bala, A., Penrose, C. T., Seyler, T. M., Mather, R. C., Wellman, S. S., Bolognesi, M. P. 2016; 29 (5): 430-435

    Abstract

    Computer-navigated total knee arthroplasty (CN-TKA) has been used to improve component alignment, though the evidence is currently mixed on whether there are clinically significant differences in long-term outcomes. Given the established increased costs and operative time, we hypothesized that the utilization rate of CN-TKA would be decreasing relative to standard TKA in the Medicare population given the current health care economic environment. We queried 1,914,514 primary TKAs performed in the entire Medicare database from 2005 to 2012. Current Procedural Terminology (CPT) and International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes were used to identify and separate CN-TKAs. Utilization of TKA was compared by year, gender, and region. Average change in cases per year and compound annual growth rate (CAGR) were used to evaluate trends in utilization of the procedure. We identified 30,773 CN-TKAs performed over this time period. There was an increase in utilization of CN-TKA per year from 984 to 5,352 (average = 572/year, R (2) = 0.85, CAGR = 23.58%) from 2005 to 2012. In contrast, there was a slight decrease in overall TKA utilization from 264,345 to 230,654 (average = 4297/year, R (2) = 0.74, CAGR = - 1.69%). When comparing proportion of CN-TKA to all TKAs, there was an increase from 0.37 to 2.32% (average 0.26%/year, R (2) = 0.88, CAGR = 25.70%). CN-TKA growth in males and females was comparable at 24.42 and 23.11%, respectively. The South region had the highest growth rate at 28.76%, whereas the Midwest had the lowest growth rate at 15.51%. The Midwest was the only region that peaked (2008) with a slow decline in utilization until 2012. Despite increased costs with unclear clinical benefit, CN-TKA is increasing in utilization among Medicare patients. Reasons could include patient preference, advertising, proper of coding the procedure, and increased publicly available information about arthroplasty options.

    View details for DOI 10.1055/s-0035-1564724

    View details for Web of Science ID 000379848500016

    View details for PubMedID 26480343

  • How Do Previous Solid Organ Transplant Recipients Fare After Primary Total Knee Arthroplasty? JOURNAL OF ARTHROPLASTY Klement, M. R., Penrose, C. T., Bala, A., Wellman, S. S., Bolognesi, M. P., Seyler, T. M. 2016; 31 (3): 609-?

    Abstract

    Total knee arthroplasty (TKA) has been proven to increase knee outcome scores after solid organ transplantation (SOT), but many authors are concerned about a higher complication rate. The purpose of this study is to evaluate the complication profile of TKA after previous SOT.A search of the entire Medicare database from 2005 to 2011 was performed using International Classification of Disease, version 9, codes to identify 3339 patients who underwent TKA after 1 or more solid organ transplants including the kidney (2321), liver (772), lung (129), heart (412), and pancreas (167). A cohort of 1,685,295 patients served as a control with minimum 2-year follow-up. Postoperative complications at 30-day, 90-day, and overall time points were compared between the 2 cohorts.Patients with any SOT were younger (age: <65, odds ratio [OR]: 6.58, P < .001), male (OR: 1.88, P < .001), and medically complex (significant increase in 28 of 29 Elixhauser comorbidities, P < .05). There was a significant increase (P < .05) in 11 of 13 (84.6%) recorded postoperative medical complications rates at 90 days. There was a significant increase overall in periprosthetic infection (OR: 2.11, P < .001), periprosthetic fracture (OR: 1.78, P < .001), and TKA revision (OR: 1.36, P < .001). When analyzed by individual organ, heart and lung transplants carried the fewest medical and surgical complications.The results of this study demonstrate that patients with previous SOT who undergo elective primary TKA have more postoperative complications in the global period and at short-term follow-up. Yet, complication profiles by individual organ varied significantly.

    View details for DOI 10.1016/j.arth.2015.10.007

    View details for Web of Science ID 000370663800010

    View details for PubMedID 26639984

  • Outcomes after Total Knee Arthroplasty for post-traumatic arthritis KNEE Bala, A., Penrose, C. T., Seyler, T. M., Mather, R. C., Wellman, S. S., Bolognesi, M. P. 2015; 22 (6): 630-639

    Abstract

    Total Knee Arthroplasty (TKA) is an important treatment for posttraumatic arthritis (PTA), but evidence on outcomes is sparse. The purpose of this study was to evaluate the impact of PTA versus primary osteoarthritis (OA) on postoperative outcomes after TKA.We queried the entire Medicare database from 2005 to 2012. International Classification of Diseases, 9th revision and Current Procedural Terminology codes were used to identify the procedure, indication, and complications. Patients with minimum two-years follow-up were selected. Odds ratios (ORs), confidence intervals, and p-values (p) were calculated.For PTA, 3509 patients had TKA. For OA, 257,611 patients with TKA served as controls. The average Charlson Comorbidity Index for both groups was five. PTA patients were younger; only eight out of 29 Elixhauser comorbidities were higher. PTA patients had higher incidence of periprosthetic infection (OR 1.72, p<0.001), cellulitis or seroma (OR 1.19, p<0.001), knee wound complications (OR 1.80, p<0.001), TKA revision (OR 1.23, p=0.01), and arthrotomy/incision and drainage (OR 1.55, p<0.001). Blood transfusion rate was lower in PTA patients. There were no significant differences in bleeding complications, prosthetic dislocation, broken prostheses, periprosthetic fracture, osteolysis and polywear, neurovascular injury, and extensor mechanism rupture.This study represents, to our knowledge, TKA outcomes in the largest cohort of PTA patients to date. Our findings indicate that these patients are at higher risk for many, but not all, postoperative surgical complications despite being as healthy as patients receiving TKA for primary OA.

    View details for DOI 10.1016/j.knee.2015.10.004

    View details for Web of Science ID 000367634100032

    View details for PubMedID 26526636