Orthopedics 2020 Projects

Project Title: The Impact of Computer Navigation on Screw Number and Screw Length in Reverse Total Shoulder Arthroplasties

Faculty Mentor: Joseph King
Email: kingjj@ortho.ufl.edu 

Student: Keegan Hones 
Email: khones@ufl.edu  

Research Project Description:

Reverse Total Shoulder Arthroplasty (RTSA) surgery was approved by the FDA for use in the United States in 2003, and since then, RTSA has significantly impacted the management of shoulder arthritis patients with non-functional rotator cuffs or tears which could not be adequately treated with an anatomical Total Shoulder Arthroplasty (TSA). Recent numbers show RTSAs are now estimated to be done on over 20,000 patients yearly in the United States(1) and these numbers are showing increasing trends(2). This procedure has continuously evolved to include management of fractures, isolated massive rotator cuff tears, revision from TSA, and management of oncologic pathology(3), with postoperative results showing functional outcomes in many patients(4).

Despite all these benefits, RTSA surgery is not without risks. The most common complications include neurologic injury, periprosthetic fracture, hematoma, infection, scapular notching, dislocation, mechanical baseplate failure, and acromial fracture(5). In efforts to improve surgical outcomes and minimize risk, computer navigation for glenoid baseplate placement in shoulder arthroplasty surgery was created. Computer navigation involves 3-D computer preoperative planning of baseplate placement per the surgeon’s preference, meshing that model with bony landmarks intraoperatively using small sensors, and then navigation preparation of the glenoid for the baseplate and placement of the baseplate screws in the best position based on the surgeon’s preference. Computer navigation for RTSA surgery became available with the idea being that the computer-assisted shoulder replacement surgery allows surgeons to place screws more precisely than what can be done with the human eye, allowing surgeons to have excellent fixation with less screws at the time of implantation. Prior to approval for shoulder surgery, computer navigation has been utilized for total knee arthroplasties for many years now, with evidence of improved postoperative alignment compared to conventional total knee arthroplasty(6,7,8). Given the success in knee surgery, it is thought that similar improvements in RTSA implant placement and potential beneficial impacts on clinically significant outcomes are possible through computer navigation.

To this point, there has not been an in-depth analysis of how computer navigation technology in RTSA surgery has affected patient outcomes and/or complications though. It is well known that poor screw placement and placement of too many screws risk complications such as nerve irritation, scapular spine fractures, and glenoid fractures(9,10). Additionally, previous studies have acknowledged surgical benefits of using fewer screws in RTSA without significant negative effect on overall implant baseplate motion(11). Thus, it is important to further elucidate whether computer navigation has any effect on these possible complications. This would be the first study to evaluate the effect that computer navigation has on screw length and/or number of screws used in RTSA. With more patients undergoing RTSA, and with current estimates indicating acromial and/or scapular spine fractures affect about 2.8% of patients after RTSA(12), it is thought that computer navigation in RTSA surgery is leading to less screws being used and a shorter average screw length, and thus surgical outcomes may be improving and complications may decrease.

We will test the hypothesis that radiographs show patients undergoing reverse total shoulder arthroplasty surgery with computer navigation required less screws and used longer screws than patients who had a RTSA before computer navigation was used. It is thought that computer navigation improves the execution of preoperative planning, intraoperative implant placement, and potentially outcomes. By studying screw qualities specifically, we can start to assess quantitatively these hypothesized improvements in surgical outcomes and decreases in complications for the benefit of patients undergoing reverse total shoulder arthroplasties.


  1. Westermann, Robert W, et al. “Reverse Shoulder Arthroplasty in the United States: A Comparison of National Volume, Patient Demographics, Complications, and Surgical Indications.” The Iowa Orthopaedic Journal, vol. 35, 2015, pp. 1-7.
  2. Dillon, Mark T., et al. “Yearly Trends in Elective Shoulder Arthroplasty, 2005-2013.” Arthritis Care & Research, vol. 69, no. 10, 19 Dec. 2016, pp. 1574–1581., doi:10.1002/acr.23167.
  3. Drake, Gregory N., et al. “Indications for Reverse Total Shoulder Arthroplasty in Rotator Cuff Disease.” Clinical Orthopaedics and Related Research®, vol. 468, no. 6, June 2010, pp. 1526–1533., doi:10.1007/s11999-009-1188-9.
  4. Monir, Joseph G., et al. “Reverse Shoulder Arthroplasty in Patients Younger than 65 Years, Minimum 5-Year Follow-Up.” Journal of Shoulder and Elbow Surgery, 7 Feb. 2020, doi:10.1016/j.jse.2019.10.028.
  5. Cheung E., Willis M., Walker M., Clark R., Frankle M.A., “Complications in Reverse Total Shoulder Arthroplasty.” Journal of the American Academy of Orthopaedic Surgeons, 19(7):439–449, July 2011
  6. Mason, J. Bohannon, et al. “Meta-Analysis of Alignment Outcomes in Computer-Assisted Total Knee Arthroplasty Surgery.” The Journal of Arthroplasty, vol. 22, no. 8, 1 Dec. 2007, pp. 1097–1106., doi:10.1016/j.arth.2007.08.001.
  7. Suero, Eduardo M., et al. “Computer Navigation for Total Knee Arthroplasty Achieves Better Postoperative Alignment Compared to Conventional and Patient-Specific Instrumentation in a Low-Volume Setting.” Orthopaedics & Traumatology: Surgery & Research, vol. 104, no. 7, Nov. 2018, pp. 971–975., doi:10.1016/j.otsr.2018.04.003.
  8. Petursson, Gunnar, et al. “Computer-Assisted Compared with Conventional Total Knee Replacement.” The Journal of Bone and Joint Surgery, vol. 100, no. 15, 1 Aug. 2018, pp. 1265–1274., doi:10.2106/jbjs.17.01338.
  9. Crosby, Lynn A., et al. “Scapula Fractures After Reverse Total Shoulder Arthroplasty: Classification and Treatment.” Clinical Orthopaedics and Related Research®, vol. 469, no. 9, 2011, pp. 2544–2549., doi:10.1007/s11999-011-1881-3.
  10. Otto, Randall J., et al. “Scapular Fractures after Reverse Shoulder Arthroplasty: Evaluation of Risk Factors and the Reliability of a Proposed Classification.” Journal of Shoulder and Elbow Surgery, vol. 22, no. 11, 7 May 2013, pp. 1514–1521., doi:10.1016/j.jse.2013.02.007.
  11. James, Jaison, et al. “Reverse Shoulder Arthroplasty Glenoid Fixation: Is There a Benefit in Using Four Instead of Two Screws?” Journal of Shoulder and Elbow Surgery, vol. 22, no. 8, 13 Jan. 2013, pp. 1030–1036., doi:10.1016/j.jse.2012.11.006.
  12. King, J. J., et al. “How Common Are Acromial and Scapular Spine Fractures after Reverse Shoulder Arthroplasty?” The Bone & Joint Journal, 101-B, no. 6, June 2019, pp. 627–634., doi:10.1302/0301-620x.101b6.bjj-2018-1187.r1

Project Title: Periprosthetic Humerus Fractures after Shoulder Arthroplasty: A Multicenter Retrospective Evaluation of Management and Outcomes

Faculty Mentor: Matthew Patrick 
Email: patrimr@ortho.ufl.edu 

Student: Mike Kuhn 
Email: zinokuhn@ufl.edu   

Research Project Description:

Since 2004, the number of shoulder arthroplasties has been increasing linearly. This can be attributed to the advent of the reverse total shoulder arthroplasty and the aging population (1). As the number of shoulder arthroplasties increases, the incidence of complications is also expected to increase. The prevalence of periprosthetic humeral shaft fractures in shoulder arthroplasty has been reported between 1.6 and 2.4% (2, 3). Although an uncommon complication, a periprosthetic fracture of the humerus is a devastating complication that significantly reduces function and can be exceedingly difficult to manage. Since the incidence of these injuries is low, there is limited information about the ideal management of this condition, and the literature that is available consists of case reports and small retrospective series (2-9). The largest series published to date reported on the management of 34 patients. (10)

It’s difficult to assess the literature for comparison of outcomes and treatment strategies due to the fact there is no widely accepted classification system. There are currently four classification systems for periprosthetic fractures of the humerus. The Wright/Cofield classification was described in 1995 (4). The classification was based on the reports of nine periprosthetic humerus fractures and is the most frequently cited classification system. The second system, described by Campbell et al., was based on a review of 21 fractures (5). The third classification system was described by Groh et al.; it was based on the review of 15 patients (6). The fourth system was described by Worland in 1999 and is an adaptation of the Vancouver Classification for periprosthetic femur fractures (3). The Wright/Cofield system is based on the location of the fracture, but it doesn’t account for fracture comminution or stability of the implant. It is also not helpful in guiding management of the fracture. Recently, Andersen retrospectively reviewed 34 patients and applied the classification system and showed good intra-observer reliability but poor inter-observer reliability (7). The Campbell and Groh classifications are similar to the Wright/Cofield classification in that they describe the location of the fracture relative to the humeral stem, but they also do not account for comminution or implant stability (5,6). These classification systems have yet to be validated. The Worland classification system takes into account location of the fracture, the degree of comminution, and the stability of the implant stem (3). As a result, the classification system can ideally be used to guide management of periprosthetic fractures and can also be used to appropriately classify fractures to facilitate accurate comparisons in the literature. However, to date, this classification system has not been validated in periprosthetic humerus fracture due to the number of patients required.

There is also limited information on the functional outcomes and complications after treatment of these fractures. As mentioned above, most reports on these injuries are small case series and reports. In most of these series, functional scores were not reported (2-6, 8, 9). In order to report clinically useful outcomes scores, a large number of patients will be needed, and the outcomes need to be stratified based on fracture classification and treatment strategy utilized. There is also limited information on the appropriate treatment for these injuries. Case reports have discussed non-operative management, open reduction internal fixation (ORIF), and revision of the shoulder prosthesis with or without ORIF (2-10). Again, because of the small numbers and inconsistent classification results, studies are difficult to compare and arrival at a conclusion for best management is complicated.

As mentioned above, we believe that the Worland classification system has the highest potential to properly classify fractures and appropriately guide fracture management. Our hope is that by creating a large enough study cohort, definitive conclusions can be made about classification, management, and expected outcomes, while also documenting the rate of complications. If a certain classification system can be validated, we will apply the appropriate classification to all fractures that were treated at the 2+ institutions and evaluate the different management strategies, functional outcomes, fracture union rates, and times to union. If no system can be statistically validated, we plan to set forth our own classification system for periprosthetic humerus fractures that has a high intra- and inter-observer reliability, as well as high predictive success for appropriate fracture management and functional outcomes.


  1. Kim SH, Wise BL, Zhang Y, Szabo M. Increasing incidence of shoulder arthroplasty in the United States. JBJS. 2011; 93: 2249-54.
  2. Boyd AD, Thornhill TS, Barnes CL. Factures adjacent to humeral prostheses. J Bone joint Surg Am. 1992; 74: 1498-504.
  3. Worland RL, Kim DY, Arredondo J. Periprosthetic humeral fracture: management and classification. j Shoulder Elbow surg. 1999;8: 590-4.
  4. Wright TW, Cofield RH. Humeral fractures after shoulder arthroplasty. JBJS. 1995; 77: 1340- 46.
  5. Campbell JT, Moore RS, Iannotti JP, Norris TR, Williams GR. Periprosthetic humeral fractures: mechanisms of fracture and treatment options. JSES. 1998; 7: 406-13.
  6. Groh GI, Keckman MM, Wirth MA, Curtis RJ, Rockwood CA. Treatment of fractures adjacent to humeral prostheses. JSES. 2008; 17: 85-89.
  7. Andersen JR, Williams CD, Cain R, Mighell M, Frankle M. Surgically treated humeral shaft fractures following shoulder arthroplasty. JBJS 2013; 95: 9- 18.
  8. Kim DH, Clavert P, Warner J. Displaced periprosthetic humeral fracture treated with functional bracing: A reports of two cases. JSES. 2005; 14: 221-223.
  9. Kumar S, Sperling J, Haidukewych G, Cofield R. Periprosthetic humeral fractures after shoulder arthroplasty. JBJS. 2004; 86-A: 680-89.
  10. Wutzler S, Laurer H, Hahnstock S, Geiger E, Beuhren V, Marzi I. Periprosthetic humeral fractures after shoulder arthroplasty: operative management and functional outcome. Arch Orthop Trauma Surg. 2009; 129: 237-43.

Project Title: Management of severe acetabular defects in revision THA with jumbo cups and posterior column plating

Faculty Mentor: Luis Pulido 
Email: pulidlf@ortho.ufl.edu 

Student: Edvinas Sipavicius 
Email: sipaviciused@ufl.edu 

Research Project Description:

THA (Total hip arthroplasty/replacement) is currently one of the most common orthopedic operations used to treat joint failure, most commonly due to osteoarthritis. THA is one of the most successful procedures in all of medicine; however, some patients may need one or more revisions of a THA for multiple reasons, most commonly: infection, repetitive hip dislocation, or mechanical failure (wear/loosening/breakage). As the number of primary THA procedures continues to rise, the burden of revision THA procedures is also expected to rise. A known problem after THA is a loss of bone mineral density around the prosthesis known as periprosthetic bone loss. Periacetabular bone loss is a common complication that must be managed to properly revise a failed THA.

Management of acetabular bone loss in revision THA entails the use of different reconstruction techniques and different implants depending on the severity of the bone loss.[1] At the University of Florida’s Department of Orthopedics, we have been using the combination of a Jumbo cup and posterior column plating to treat severe acetabular bone loss and pelvic discontinuity. Most of the studies addressing reconstructions of Paprosky III acetabular defects used other solutions[2, 3]. Tantalum augments is now the standard reconstruction technique in the U.S. to treat theses major acetabular defects. Survival rates of 92.8 % at 4.5 years have been reported in the literature.[4] Therefore, the purpose of this retrospective study is to add to the current body of literature by presenting a technique with two decades of records for treating massive acetabular bone loss and pelvic discontinuity with a Jumbo cup and posterior column plating. The hypothesis of this study is that there is a difference in survival rates of the management of acetabular bone loss in revision THA using the combination of a Jumbo cup and posterior column plating versus the standard reconstruction technique in the U.S.

As this unique surgical technique has never been described, we aim first to give the details of its realization, step-by-step using drawings, pictures, x-rays, key points and pitfalls, making it understandable and easily reproducible to the orthopaedic community.
Second, we aim to report mid- to long-term outcomes, including survivorship, of this technique. This part will include demographic data of the studied population (age, height, weight, BMI, gender, duration of follow-up, number and type of prior hip surgeries, severity of the acetabular defect, main diagnosis ICD9 or ICD10 code or actual diagnosis; length of hospital stay (LOS)). Clinical analysis will include the Merle d’Aubigné grading system[5]. The Merle d’Aubigné grading system is based on three clinical criteria (Pain, range of motion and ability to walk) and is gathered through the patients’ orthopaedic notes. This score classifies clinical results into six categories: excellent (18 points), very good (17 points), good (16 points), fair (15 points), poor (14 points) and bad (13 points). Using this grading system we will be able to compare the pre-operatives scores to those obtained at the last follow-up. Complications and re-operations (e.g. infection, dislocation, nerve palsy, fracture, loosening, etc.) will also be reported. Radiological analysis will include measurement of the abduction angle of the Jumbo cup, loosening of the cup, defined as a continuous radiolucent line wider than 2 mm and/or migration > 5 mm, and any implant breakage.


  1. Sheth, N.P., et al., Acetabular bone loss in revision total hip arthroplasty: evaluation and management. The Journal of the American Academy of Orthopaedic Surgeons, 2013. 21(3): p. 128-139.
  2. Gibon, E., et al., Acetabular reinforcement rings associated with allograft for severe acetabular defects. International Orthopaedics, 2018.
  3. Gibon, E., et al., Revision total hip arthroplasty using the Kerboull acetabular reinforcement device for Paprosky type III defects involving the inferior margin of the acetabulum: a minimum five-year follow-up study. Bone Joint J, 2018. 100-B(In presse).
  4. Grappiolo, G., et al., Trabecular Metal Augments for the Management of Paprosky Type III Defects Without Pelvic Discontinuity. The Journal of Arthroplasty, 2015. 30(6): p. 1024-1029.
  5. Biau, D.J. and R.A. Brand, Robert Merle d’Aubigné, 1900-1989. Clinical Orthopaedics and Related Research, 2009. 467(1): p. 2-6.

Project Title: Observer Accuracy and Consistency of “Center-Center” Ankle Radiograph

Faculty Mentor: Christopher Reb 
Email: rebcw@ortho.ufl.edu 

Student: Jose Zermeno
Email: emily.beydler@ufl.edu  

Research Project Description:

It has been estimated that nearly a quarter of ankle fractures involve damage to the distal tibiofibular syndesmosis. To restore proper function of the ankle joint after syndesmotic injury it is critical to correctly align the tibiofibular joints during surgical reduction. It has previously been reported that while using an open technique with direct visualization there is still a malreduction rate of up to 15% (Miller et al. 2009). A recently proposed method in current clinical use involves aligning the fibula and tibia on a modified lateral view X-ray image (Cancienne 2015). It is unknown, and therefore necessary to investigate, how accurately and consistently Orthopaedic surgeons can make a visual assessment of this X-ray image. It is also of importance to determine if an additional marker on the X-ray images will facilitate or improve the visual assessment performed by the surgeons.

It is hypothesized that if surgeons are asked to decide whether a given X-ray image is in perfect alignment or not, they will be more accurate in detecting X-rays with larger magnitudes of rotation out of ideal alignment. Surgeons will have more difficulty with judging X-rays with smaller magnitudes or those that are ideally aligned. In addition, the addition of a small marker at the center of the tibia will not improve the accuracy nor reduce the cognitive load by a significant amount.

The aim of this study is to determine the accuracy of Orthopaedic surgeons in the visual assessment of a modified lateral ankle X-ray to determine tibiofibular joint alignment. We also aim to answer the question of whether the addition of a visual marker on X-ray will aid in accuracy or reduce cognitive load.

Orthopaedic surgeon observers will be presented a randomized series of lateral ankle X-ray images. They will be tasked with judging the accuracy of the tibia and fibula alignment (perfectly aligned vs not aligned). Tibia and fibula alignment will be predetermined and fall into one of 10 categories of alignment (9 not aligned and 1 in perfect alignment). The same series of pictures will be presented again, in a different order, with the addition of a small marker at the midpoint of the tibia. The surgeons will again be tasked with judging the accuracy of the tibia and fibula alignment (perfectly aligned vs not aligned). Accuracy and Intrarater reliability will be calculated and compared for the series of images without the marker against the images with the marker. Subjective cognitive task load will be described by Paas Score and NASA Task Load Index questionnaires.


  1. Cancienne, JM, Yarboro, S. Center-center syndesmosis fixation technique. Tech Foot Ankle Surg. 2015;14(3):134-138.
  2. Koenig SJ, Tornetta P 3rd, Merlin G, Bogdan Y, Egol KA, Ostrum RF, Wolinsky PR. J Orthop Trauma. 2015 Sep;29(9):e326-30
  3. Miller AN, Carroll EA, Parker RJ, et al. Direct visualization for syndesmotic stabilization of ankle fractures. Foot Ankle Int. 2009;30:419–426
  4. Miller, AN, Barei, DP, Iaquinto, JM, Ledoux, WR, Beingessner, DM. Iatrogenic syndesmosis malreduction via clamp and screw placement. J Orthop Trauma. 2013;27(2):100-106.
  5. Zalavras C, David T. J Am Acad Orthop Surg 2007;15:330339