Accuracy of fit analysis of the patient-specific Groningen temporomandibular joint prosthesis

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.

Four-Dimensional Determination of the Patient-Specific Centre of Rotation for Total Temporomandibular Joint Replacements: Following the Groningen Principle

For patients who suffer from severe dysfunction of the temporomandibular joint (TMJ), a total joint replacement (TJR) in the form of a prosthesis may be indicated. The position of the centre of rotation in TJRs is crucial for good postoperative oral function; however, it is not determined patient-specifically (PS) in any current TMJ-TJR. The aim of this current study was to develop a 4D-workflow to ascertain the PS mean axis of rotation, or fixed hinge, that mimics the patient’s specific physiological mouth opening. Twenty healthy adult patients were asked to volunteer for a 4D-scanning procedure. From these 4D-scanning recordings of mouth opening exercises, patient-specific centres of rotation and axes of rotation were determined using our JawAnalyser tool. The mean CR location was positioned 28 [mm] inferiorly and 5.5 [mm] posteriorly to the centre of condyle (CoC). The 95% confidence interval ranged from 22.9 to 33.7 [mm] inferior and 3.1 to 7.8 [mm] posterior to the CoC. This study succeeded in developing an accurate 4D-workflow to determine a PS mean axis of rotation that mimics the patient’s specific physiological mouth opening. Furthermore, a change in concept is necessary for all commercially available TMJ-TJR prostheses in order to comply with the PS CRs calculated by our study. In the meantime, it seems wise to stick to placing the CR 15 [mm] inferiorly to the CoC, or even beyond, towards 28 [mm] if the patient’s anatomy allows this.

3D printing in oral and maxillofacial surgery: a nationwide survey among university and non-university hospitals and private practices in Germany

OBJECTIVES

Oral and maxillofacial surgery (OMFS) has undergone pioneering progress through the development of three-dimensional (3D) printing technologies. The aim of this study was to evaluate the use of 3D printing at OMFS university and non-university hospitals and private practices in Germany.

MATERIALS AND METHODS

For explorative assessment, a dynamic online questionnaire containing 10-22 questions about the current use of 3D printing and the reasons behind it was sent to OMFS university and non-university hospitals and private practices in Germany by the study group from the German Association of Oral and Maxillofacial Surgery (DGMKG).

RESULTS

In total, 156 participants responded from university (23 [14.7%]) and non-university hospitals (19 [12.2%]) and private practices without (85 [50.5%]) and with 29 (18.6%) inpatient treatment facility. Highest applications of 3D printing were in implantology (57%), microvascular bone reconstructions (25.6%), and orthognathics (21.1%). Among the participants, 37.8% reportedly were not using 3D printing. Among the hospitals and private practices, 21.1% had their own 3D printer, and 2.5% shared it with other departments. The major reason for not having a 3D printer was poor cost efficiency (37.6%). Possessing a 3D printer was motivated by independence from external providers (91.3%) and rapid template production (82.6%). The preferred printing methods were stereolithography (69.4 %) and filament printing (44.4%).

CONCLUSIONS

OMFS 3D printing is established in Germany with a wide range of applications.

CLINICAL RELEVANCE

The prevalence of 3D printing in hospitals and private practices is moderate. This may be enhanced by future innovations including improved cost efficiency.