June 14, 2018
3 min read

Patient-specific planning, navigation system improves the THA experience

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Total hip arthroplasty routinely provides patients with greatly improved quality of life, however the process of performing THA requires that many anatomical issues must be addressed that are not predicted on preoperative radiographs. Ideally, the surgeon and the operative team should be aware of all major anatomical considerations and the planned process to address these before the surgery starts.

The HipXpert System (HipXpert) allows the surgeon and surgical team to be aware of major anatomical and component considerations prior to surgery and it enables the surgeon to accomplish the task of performing THA with precision and efficiency. The system uses patient-specific CT imaging to create 3-D models, establish pelvic and femoral coordinate systems and plan component sizing and placement. The plan is provided to the surgeon who is then free to further modify the plan in an efficient manner both before and during surgery.

Smart navigation tool

The system includes a smart navigation tool (Figure 1) that is adjusted on a patient-specific basis to achieve accurate cup orientation, and it provides straightforward methods for reporting changes in leg length and offset that are based on simply obtained intraoperative information (Figure 2). Using the system, the entire team knows the planned sizes of the components and their intended positions in advance and can prepare the surgery instruments accordingly. The process can not only improve surgical accuracy, but also can accelerate the surgery and greatly reduce the need for intraoperative imaging and radiation exposure to the team.

The HipXpert System has many advantages over planning systems that do not include tracking technology and also over tracking technologies that do not incorporate intraoperative imaging. Such image-free systems are also knowledge-free in that there is not only a complete absence of information about anatomical issues and component sizing, but these are also based on establishing an unvalidated, intraoperative coordinate system, which makes all subsequent measurements similarly unvalidated.

In contrast, the smart navigation system not only provides detailed patient-specific information about anatomical considerations and component sizing but has been shown in multiple studies to be accurate. More over, it has been shown in some research to be more accurate than surgical robotics.

HipXpert Tool and planning
Figure 1. This is how the HipXpert Tool appears in the planning software.
Figure 2. The HipXpert is shown docked on a patient’s pelvis during cup placement.
Figure 3. The femoral component planning and implant overview window is shown.
Figure 4. Shown is the acetabular component planning and implant overview window.
Figure 5. Images of acetabular peripheral osteophytes are displayed in a window, which helps the surgical team develop a resection plan.

Source: J. Scott Reid, MD


Downloadable surgical plans

The workflow for a joint reconstruction practice is straightforward. The surgeon logs onto the website to download the plans for each surgery. He or she then reviews and fine-tunes the plan according any personal preferences there may be regarding the associated viewer application that runs locally on the physician’s laptop. Planning for the femoral stem (Figure 3) and for the acetabular component (Figure 4) are performed. The implant overview window shows the team the exact component sizes and reports to the surgeon the planned effects of leg length and offset change, as well of native and planned femoral anteversion and planned anteversion of the cup. When the surgeon enters the OR, he or she plugs the laptop into the rolling workstation, as well as a large touchscreen that controls the application features. The entire team then sees the proposed component sizes, prepares the instruments and calls for the implants accordingly in advance. During surgery, the surgical team works toward the planned goals and fine tunes any variables in surgery and in the plan using the touchscreen as needed. After the cup is implanted using the patient-specific smart mechanical navigation instrument, the full 3-D view of the pelvis and cup is displayed to visually confirm concordance between the plan and what is seen in surgery. In this way, the team can see any peripheral osteophytes that need to be resected (Figure 5). The team also knows the leg length and offset changes that will be affected by the surgery due to the selected neck and head components and their sizes, even before performing the trial reduction. Following completion of a satisfactory trial reduction, the implants, which are already in the room, are implanted. Intraoperative imaging is unnecessary under typical circumstances since it is already known where the components were placed.

Having such preoperative knowledge, intraoperative accuracy and streamlining of the entire operative workflow can lead to precise surgery that is efficient and safe, a predicate to optimal outcome following THA.

Disclosure: Reid reports no relevant financial disclosures.