Accuracy of an adjustable patient-specific guide for acetabular alignment in hip replacement surgery (Optihip)

Abstract

Implant malalignment in hip arthroplasty increases the risk of revision surgery due to problems such as hip instability, wear, and impingement. Traditional instrumentation lacks accuracy and does not individualize the goal. Computer-assisted surgery (CAS) and patient-specific solutions improve accuracy but add considerably to the cost, amongst other drawbacks. We developed an adjustable mechanical device, called Optihip, which is set to a patient-specific goal preoperatively and is independent of pelvis position intraoperatively. The purpose of the present study was to evaluate Optihip's accuracy ex vivo. Acetabular components were implanted into six cadaveric specimens, 12 hips, by two surgeons, with the device individually adjusted according to preoperative templating on computed tomography (CT) images relative to defined acetabular rim landmarks; options also exist for templating on single or biplanar X-rays. Intraoperatively, the device was positioned on the corresponding anatomical landmarks allowing the insertion of a guide pin, which then defined the desired orientation of the acetabular cup during impaction. Mean absolute difference between the preoperatively planned cup alignment and final acetabular cup orientation, measured from postoperative CT images, was 2.5±1.2° for inclination and 2.5±2.2° for version with maximum values of 4.7° and 6.8°, respectively. Compared with previous in vivo reports, Optihip guided the acetabular cup orientation more accurately than conventional hip arthroplasty, and comparably to CAS or patient-specific systems, while fitting into the normal surgical workflow. Although clinical testing is required to confirm these experimental results, the positive ex vivo accuracy suggests good potential for improving revision rates and patient functional outcome.

Good vs Poor Results After Total Hip Arthroplasty: An Analysis Method Using Implant and Anatomic Parameters With the EOS Imaging System

“…The lack of statistical significance between the good-results and poor-results groups on most parameters confirms the common finding that some patients look-good-feel-bad, whereas some patients look-bad-feel-good. The fact that there was a significant difference in acetabular orientation agrees with the recognized need to improve the accuracy of component placement [4,26]. Fig.…”

“…Component placement, including acetabular cup orientation and depth, and the individual's functional posture, play key roles [4,5]. The challenge is how to measure these.…”

Computer-Assisted Orthopedic Surgery: Current State and Future Perspective

“…By this means, the planned position and orientation of the template in spatial relation to the bone are stored in a structural way and can be reproduced intra-operatively by adjusting the contact faces of the templates until an exact fit to the bone is achieved. By integrating holes and/or slots, individualized templates function as tool guides, e.g., for the preparation of pedicle screw holes ( 32 ) or as cutting jigs used in total knee and hip replacement surgery ( 33 – 35 ).…”

“…Recently, computer-assisted surgery using individual templates has gained increasing attention. Initially developed for pedicle screw fixation ( 32 ), such a technique has been successfully reintroduced to the market for total knee arthroplasty ( 33 , 68 , 69 ), hip resurfacing ( 34 , 70 ), total hip arthroplasty ( 35 ), and pelvic tumor resection ( 71 , 72 ) (See Figure 7 for an example). It should be noted that most of the individual templates are produced using additive manufacturing techniques, while most of the associated implants are produced conventionally.…”

Validating a Modified Circle Theorem Method for the Measurement of Acetabular Cup Anteversion on Plain Radiography with Intra-Operative Data from Robotic Assisted Total Hip Arthroplasty

“…Several methods have been developed to help surgeons correctly position the acetabular component intra-operatively. These methods can be divided into implantation with the assistance of anatomical landmarks [6], mechanical alignment guides [7], computer navigation [8] and robotic assistance [9].…”