Accuracy of custom temporomandibular joint replacement surgery using a virtual surgical planning protocol

Novel Use of Virtual Reality and Augmented Reality in Temporomandibular Total Joint Replacement Using Stock Prosthesis

This technical innovation demonstrates the use of ImmersiveTouch Virtual Reality (VR) and Augmented Reality (AR)-guided total temporomandibular joint replacement (TJR) using Biomet stock prosthesis in 2 patients with condylar degeneration. TJR VR planning includes condylar resection, prosthesis selection and positioning, and interference identification. AR provides real-time guidance for osteotomies, placement of prostheses and fixation screws, occlusion verification, and flexibility to modify the surgical course. Radiographic analysis demonstrated high correspondence between the preoperative plan and postoperative result. The average differences in the positioning of the condylar and fossa prosthesis are 1.252 ± 0.269 mm and 1.393 ± 0.335 mm, respectively. The main challenges include a steep learning curve, intraoperative technical difficulties, added surgical time, and additional costs. In conclusion, the case report demonstrates the advantages of implementing AR and VR technology in TJR's using stock prostheses as a pilot study. Further clinical trials are needed prior to this innovation becoming a mainstream practice.

Biomechanical Evaluation of Temporomandibular Joint Reconstruction Using Individual TMJ Prosthesis Combined with a Fibular Free Flap in a Pediatric Patient

The main aim of this study was to perform a complex biomechanical analysis for a custom-designed temporomandibular joint (TMJ) prosthesis in combination with a fibular free flap in a pediatric case. Numerical simulations in seven variants of loads were carried out on 3D models obtained based on CT images of a 15-year-old patient in whom it was necessary to reconstruct the temporal-mandibular joints with the use of a fibula autograft. The implant model was designed based on the patient's geometry. Experimental tests on a manufactured personalized implant were carried out on the MTS Insight testing machine. Two methods of fixing the implant to the bone were analyzed-using three or five bone screws. The greatest stress was located on the top of the head of the prosthesis. The stress on the prosthesis with the five-screw configuration was lower than in the prosthesis with the three-screw configuration. The peak load analysis shows that the samples with the five-screw configuration have a lower deviation (10.88, 0.97, and 32.80%) than the groups with the three-screw configuration (57.89 and 41.10%). However, in the group with the five-screw configuration, the fixation stiffness was relatively lower (a higher value of peak load by displacement of 171.78 and 86.46 N/mm) than in the group with the three-screw configuration (where the peak load by displacement was 52.93, 60.06, and 78.92 N/mm). Based on the experimental and numerical studies performed, it could be stated that the screw configuration is crucial for biomechanical analysis. The results obtained may be an indication for surgeons, especially during planning personalized reconstruction procedures.

A five-year review of the OMX temporomandibular prosthetic total joint replacement system

PURPOSE

The aim of this study was to undertake a 5-year review of the OMX temporomandibular prosthetic total joint replacement system (OMX-TMJ).

METHODS

Data was collected from patients who had an OMX-TMJ implanted between May 2015 and November 2020 at Epworth-Freemasons and St. Vincent's hospitals in Melbourne, Australia. The data points included patient demographics, primary diagnosis, and clinical outcomes in terms of visual analogue scale (VAS) for pain, maximum inter-incisal mouth opening, and complication events.

RESULTS

There were 206 OMX-TMJ devices implanted in 151 patients over the 5-year study period. The vast majority were female patients (n = 137, 90.7%) with a mean age of 44.8 years (range 20-76 years) at the time of surgery. Most patients presented with primary (idiopathic) osteoarthritis (119 joints-57.8%) that failed to respond to conservative measures. Based on a mean follow-up period of 36 months (range 12 months to 73 months), the average mouth opening improved from 30.8 mm pre-surgery to an average of 39.1 mm following OMX-TMJ surgery (p < 0.05). Joint pain (VAS: 0-10) significantly improved from 6.14 pre-surgery to 0.87 following OMX-TMJ surgery (p < 0.001). Twenty-one patients (13.9%) experienced device-related complications which resulted in explantation of 7 (3.4%) OMX-TMJ devices over the 5-year period.

CONCLUSION

This study shows that the OMX-TMJ prosthetic total joint replacement system is a reasonably safe, versatile, and reliable implant that effectively improves mandibular opening and reduces joint pain across a broad range of end-stage TMJ disorders.

Condylar Position is Maintained in Maxillomandibular Advancement Surgery Utilizing Custom Cutting Guides and Plates

PURPOSE

The objective of this study is to compare virtual surgical planned (VSP) and postoperative condylar positioning outcomes in patients who underwent maxillomandibular advancement surgery with custom mandibular cutting guides and osteosynthesis plates to establish reliability and effectiveness using these forms of technology.

METHODS

An ambispective case series was performed by obtaining preoperative and postoperative computed tomography (CT) scans of obstructive sleep apnea patients who underwent maxillomandibular advancement surgery with VSP and custom printed mandibular cutting guides and plates at the San Francisco Veterans Affairs Healthcare System from February 2019 to October 2021. The primary predictor variables were the use of custom guides and plates compared to VSP over the course of a year. The outcome variable was the maintained condylar position, defined as the mean differences between the VSP and postoperative positioning. The comparison group was the preoperative VSP position. Covariates were planned surgical movements, age, and gender. Measurements were taken bilaterally in sagittal CT sections measuring the condylar positioning within the posterior space, superior space, and anterior space of the glenoid fossae. Similarly, coronal CT section measurements were taken to measure the condylar positioning within the coronal lateral space, coronal central space, and coronal medial space. A Wilcoxon signed rank test was used.

RESULTS

This study included 6 male participants (n = 6) aged 32 to 57 years (mean 46.5). The median differences for the posterior space, superior space, and anterior space planned versus postoperative position were 0.25 (0.40), 0.40 (0.35), and 0.40 (0.55) mm, respectively. The median differences for the coronal lateral space, coronal central space, and coronal medial space planned versus postoperative position were 0.30 (0.30), 0.78 (0.70), and 0.40 (0.30) mm, respectively. There was no statistically significant difference in the planned and postoperative condylar position (Wilcoxon signed rank test, P > .5). A qualitative analysis showed little to no displacement or rotation of the condyle in the virtually planned and postoperative condylar positions.

CONCLUSIONS

Qualitative and quantitative comparisons of the preoperative virtual surgical planned and the postoperative condylar position with the use of custom-printed mandibular cutting guides and plates support the null hypothesis that there is no difference between planned and postoperative positioning.