Templating software is advantageous when preoperative planning for shoulder arthroplasty
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Templating software can be helpful in cases when a CT scan alone is insufficient for proper preoperative planning of total shoulder arthroplasty and intraoperative placement of TSA implants, particularly the glenoid component.
Surgeons use TSA templating software programs for various reasons based on their experience. Research has shown some advantages with use of this technology including overall decreased deviation in version and inclination of glenoid components that are implanted.
Source: Joseph A. Abboud, MD, FAAOS
There is growing evidence that this technology improves the execution of the operation and potentially the outcome for patients, as well.
In addition, use of the templating software provides an opportunity for fellows and residents to stop, think about a case, discuss it and simulate its execution prior to carrying out the surgical procedure. Although any time the surgeon spends with a fellow or resident to think through the logistics of the procedure may add to the overall surgical time, it is not wasted time, because this effort can result in an invaluable opportunity for team education.
Impact on joint kinematics, fixation
Joseph P. Iannotti, MD, PhD, has been a leader in the trend of virtual planning and patient-specific instrumentation for TSA and has inspired other surgeons to use this technology, in particular with regard to glenoid component positioning. His research has shown templating and planning may have an indirect effect on many aspects of the surgery, including joint kinematics, soft tissue forces, contact pressures and the stresses on the fixation.
Improper positioning and sizing of TSA implants, which can be mitigated through templating, can lead to shoulder instability, which may then lead to early glenoid loosening and possibly rotator cuff issues, as well (Figure 1).
Preoperative TSA planning and use of patient-specific instruments (PSI) may not completely prevent gradual glenoid component subluxation and subsequent glenoid component dislocation, but it plays a role at the front end of the surgery ensuring that the surgeon does their due diligence contemplating the implants to be used during surgery. With regard to the glenoid, templating software helps the surgeon recognize the severity of the glenoid erosion, the presence of any excessive inclination/subluxation, as well the extent of glenoid bone loss and any joint line medialization. Furthermore, it permits the surgeon to simulate the preoperative sizes of glenoid components that may be used and assesses the adequacy of the backside glenoid support. Additionally, preoperative TSA templating improves the workflow of the OR and minimizes the inventory of components and instruments needed for procedures, which is especially critical as more shoulder arthroplasties are being performed in ASCs vs. the hospital setting.
There are modest drawbacks to using templating software including potential added cost if patient-specific guides are made.
3D vs 2D virtual planning
Virtual planning in 3D offers advantages over 2D virtual planning as it is more accurate in terms of how the head height, canal diameter and wear of the glenoid are assessed, including the paleoglenoid and neoglenoid (Figure 2). Software from each templating company uses similar algorithms, although the algorithms are somewhat unique, meaning each software company has different nomenclature with which to become familiar. Similar among software packages, however, are the ability to help the surgeon determine the starting retroversion, inclination and subluxation of the patient’s shoulder. This also provides visual feedback regarding the amount of central axis reaming that is necessary, the location where the implant is being seated, and the ability to attain 95% implant coverage.
Templating can be helpful in a variety of patients, including patients with B2 or B3 glenoids, with deformity or severe osteoarthritis. It is also useful to determine preoperatively whether a patient who is indicated for TSA, and has an intact rotator cuff, may have a better result with RSA, for example (Figure 3). This may be due to reasons such as severe posterior humeral subluxation (>80%) or extreme retroversion greater than 35°.
If patient-specific guides are used, these help to perfectly place the centering pin, which is critical for templated TSA because the glenoid reaming and other steps of the procedure are built off of the positioned pin. Iannotti and colleagues showed in several studies that TSA is more reproducible when this technology is used vs. the “eyeball” method. Once the pin is placed, the remainder of the surgery involves execution of the surgical steps, including reaming of the glenoid face, drilling the peripheral peg holes and central hole for the glenoid component and cementing the glenoid into position (Figure 4).
Reproducible operation
TSA templating is a technology that has shown increasing value in the last 10 years in terms of the ability to perform shoulder arthroplasty. Often, manufacturers offer the templating feature for free to surgeons to use. However, there may be a cost associated with using PSI in the OR. Regardless, templating TSA surgery is worth learning and using to achieve better surgical planning and execution in the OR.
- References:
- Heylen S, et al. J Shoulder Elbow Surg. 2016;doi:10.1016/j.jse.2015.07.024.
- Iannotti J, et al. J Bone Joint Surg Am. 2014;doi:10.2106/JBJS.L.01346.
- Iannotti JP, et al. J Bone Joint Surg Am. 2015;doi:10.2106/JBJS.N.00493.
- Iannotti JP, et al. J Bone Joint Surg Am. 2019;doi:10.2106/JBJS.17.01614.
- Schoch BS, et al. J Shoulder Elbow Surg. 2020;doi:10.1016/j.jse.2020.03.014.
- For more information:
- Joseph A. Abboud, MD, FAAOS, can be reached at Rothman Orthopaedic Institute, 925 Chestnut St., 5th Floor, Philadelphia PA 19107; email: abboudj@gmail.com.
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