Computer-Assisted Navigation—Total Knee Arthroplasty

ArthroNavi framework: stereo endoscope-guided instrument localization for arthroscopic minimally invasive surgeries

Significance

As an example of a minimally invasive arthroscopic surgical procedure, arthroscopic osteochondral autograft transplantation (OAT) is a common option for repairing focal cartilage defects in the knee joints. Arthroscopic OAT offers considerable benefits to patients, such as less post-operative pain and shorter hospital stays. However, performing OAT arthroscopically is an extremely demanding task because the osteochondral graft harvester must remain perpendicular to the cartilage surface to avoid differences in angulation.

Aim

We present a practical ArthroNavi framework for instrument pose localization by combining a self-developed stereo endoscopy with electromagnetic computation, which equips surgeons with surgical navigation assistance that eases the operational constraints of arthroscopic OAT surgery.

Approach

A prototype of a stereo endoscope specifically fit for a texture-less scene is introduced extensively. Then, the proposed framework employs the semi-global matching algorithm integrating the matching cubes method for real-time processing of the 3D point cloud. To address issues regarding initialization and occlusion, a displaying method based on patient tracking coordinates is proposed for intra-operative robust navigation. A geometrical constraint method that utilizes the 3D point cloud is used to compute a pose for the instrument. Finally, a hemisphere tabulation method is presented for pose accuracy evaluation.

Results

Experimental results show that our endoscope achieves 3D shape measurement with an accuracy of < 730    μ m . The mean error of pose localization is 15.4 deg (range of 10.3 deg to 21.3 deg; standard deviation of 3.08 deg) in our ArthroNavi method, which is within the same order of magnitude as that achieved by experienced surgeons using a freehand technique.

Conclusions

The effectiveness of the proposed ArthroNavi has been validated on a phantom femur. The potential contribution of this framework may provide a new computer-aided option for arthroscopic OAT surgery.

Minimal invasive and computer-assisted total knee replacement compared with the minimal invasive technique: a prospective, randomized trial with short-term outcomes

INTRODUCTION

Up to now, no prospective, randomized comparisons between minimal invasive and computer-assisted total knee arthroplasty (MICA-TKA), and minimal invasive technique (MI-TKA) has been documented to evaluate not only clinical, but also radiologic results of the MICA-TKA. This prospective, randomized study was performed to compare the short-term results of MICA-TKA with minimal invasive technique MI-TKA for 6-month follow-up.

PATIENTS AND METHODS

We reported the clinical and radiological results of 80 subjects who had cruciate-substituting, TKA-implanted primary total knee arthroplasties using either minimal invasive and computer-assisted technique (40 patients Group I) or minimal invasive technique (40 patients, Group II). Tourniquet time, length of skin incision, and total blood loss were compared. Knee society scores (KSSs), knee society functional scores (KSFSs), range of motion (ROM), and radiographic results were assessed and reported preoperatively and at 6-month follow-up.

RESULTS

The accuracy of the implantations in relation to the coronal mechanical axis in Group I was superior to that of Group II (P < 0.05). The femoral rotational profile revealed the prosthesis in Group I that was implanted with significantly less internal rotation than in Group II. The average blood loss in patients of Group I was significantly reduced as compared to patients of Group II. No significant difference was detected in terms of tourniquet time or length of skin incision. Clinical results, with regard to ROMs and KSSs, as well as KSFSs were equally good in both the groups.

CONCLUSIONS

Better alignment and similarity of good clinical results at short-term follow-up may provide subjects who receive MICA-TKA with long-term endurance of their implants. Further studies on longer-term outcomes and functional improvements are required to validate these possibilities.