Avoiding and Managing Temporomandibular Joint Total Joint Replacement Surgical Site Infections

Evaluation of grafts fixation techniques for temporomandibular joint reconstruction with medial femoral condyle flap: A numerical study

Reconstruction for large-scale temporomandibular joint (TMJ) defects can be challenging. Previously, we utilized the medial femoral condyle (MFC) flap for TMJ reconstruction. However, the optimal fixation method remains uncertain. In this study, finite element analysis was used to study the effects of three different fixation types of bone graft: overlap type, bevel type, and flush type. Models of different fixation types of MFC flap were reconstructed from CT images. A standard internal fixation model for extracapsular condylar fracture was also included as a control. Displacement of bone graft, deformation of plates and screws, and stress distribution of plates, screws, and cortical and cancellous of the bone graft were analyzed by finite element analysis to investigate their biomechanical features. The displacement of the bone graft and deformation of plates and screws in three different fixation types showed no significant difference. The overlap type and flush type of fixation displayed the lowest and highest stress respectively. All three fixation types could satisfy the mechanical requirement and face no risk of breakage and the major displacement of the MFC bone graft. These results provide insights into the optimal fixation approach for MFC bone grafts, offering valuable guidance and reference for clinical application.

Temporomandibular joint alloplastic replacement failure

Temporomandibular joint disorders are common, with alloplastic temporomandibular joint replacement (TMJR) being one method of addressing chronic pain and movement limitations that cannot otherwise be managed. Despite this, TMJR has known complications that can lead to failure. We present our experience of managing these cases and review the current evidence on the management and outcomes of alloplastic TMJR failures. Until 2015 our unit regularly used Dundee full metal prostheses, and encountered multiple issues such as infection, heterotopic bone formation, and progression of osteoarthritis beneath the condylar element. We also present our experience with other standard TMJR implants. One common cause of failure we observed is improper placement of a prosthesis due to poor technique, for instance, placement of the fossa implant too close to the ear canal can cause unresolved postoperative pain. There is no consensus on the management of TMJR, but non-surgical measures are preferred initially and surgical intervention is reserved for later stages. Recently our unit has managed numerous failure cases, employing a multidisciplinary approach combined with thorough preoperative planning and postoperative care, which has proven effective in reducing complications and improving outcomes. Based on our experience, we do not recommend the use of Dundee full metal prostheses for TMJR. Appropriate training in the placement of contemporary implants remains crucial. Suboptimal alignment of the implant in some cases does not need surgical intervention, but surgical management is justifiable in cases of persistent symptoms and functional limitations. When placing stock implants or designing a custom-made implant for an adult, we recommend that the posterior edge of the fossa component is at least 3 mm away from the bone of the ear canal.

Effect of duration of preoperative pain on outcomes of total temporomandibular joint replacement

The purpose of the study was to determine whether the duration of preoperative pain affects outcomes of temporomandibular joint replacement (TMJR). Twenty-seven patients who underwent primary TMJR between 1 July 2020 and 31 October 2022 were retrospectively assessed for duration of preoperative pain, level of preoperative and postoperative pain on a visual analogue scale (VAS; 0, none; 10, severe), preoperative and postoperative range of motion (ROM), and net change in quality of life (much better, better, same, worse, much worse), reporting the longest available follow up for each patient. Surgical success was defined as postoperative pain of ≤4 and postoperative ROM of ≥30 mm, or net change (Δ) in ROM of ≥10 mm. Regression analyses evaluated associations between independent variables and postoperative pain and ROM. At a mean follow-up of 17.8 (SD: 6.8, range 3-32) months , pain (5.1, SD: 2.2, p < 0.001) and ROM (9.3 mm, SD: 8.0, p<0.001) significantly improved. Quality of life was much better in 16 patients, better in eight, the same in one, and worse in two. Longer duration of preoperative pain tended to be negatively associated with postoperative ROM (β = -0.27; 95% CI -0.6 to 0.0; p = 0.078) but was not associated with severity of postoperative pain. Surgical success was achieved in 23/27 patients. The successful group tended to have lower pain on VAS preoperatively (5.9, SD: 1.9) vs 7.5, SD: 1.3) and postoperatively (0.4, SD: 0.8 vs 4.8, SD: 2.6), and greater improvement in quality of life (much better: 14/23 vs 2/4). In conclusion, longer duration of preoperative pain tended to be associated with worse postoperative ROM following TMJR. Higher preoperative pain may be a predictor for unsuccessful surgery.

The Chimeric LFC and DCIA Flap in Combined Mandibular and Condylar Head and Neck Reconstruction-A Case Series

Background: Defects of the ascending ramus of the mandible, including the condylar head and neck or the whole temporomandibular joint (TMJ), are difficult to reconstruct. Reconstruction is mainly based on the use of alloplastic joint prosthesis, costochondral grafting, distraction osteogenesis of the dorsal part of the mandibular ramus, or osseous microvascular flaps of various origin. With the objective of developing a method that overcomes the restrictions of these methods, we recently introduced a sequential chimeric flap consisting of a lateral femoral condyle flap (LFC) and deep circumflex iliac artery flap (DCIA) for reconstruction of up to half of the mandible and the condylar head and neck. Methods: The chimeric flap was used in four patients with the following diagnoses: therapy-refractory osteomyelitis, extended recurrent odontogenic keratozyst, Goldenhar syndrome, and adenocarcinoma of the parotid gland. After a diagnostic workup, LFC and DCIA flaps were harvested in all patients and used in a sequential chimeric design for the reconstruction of the mandibular body and condylar head and neck. Results: Follow-up from at least 24 months up to 70 month after surgery showed a successful reconstruction in all four patients. The LFC provided a cartilaginous joint surface, allowing for a satisfactory masticatory function with a stable occlusion and unrestricted mouth opening and preserved or regained lateral and medial excursions in all patients. The DCIA allowed for a bony reconstruction anatomically resembling a non-atrophied mandibular body. No flap-related complications were observed. Conclusions: The sequential chimeric LFC and DCIA flap is an appropriate method for reconstructing up to half of the mandible and the condylar head and neck. It is suitable in cases where alloplastic joint replacement cannot be used or where other methods have failed. Due to the necessity of harvesting two flaps, the burden of care is increased, and a careful indication is required. The technique is reserved for maxillofacial surgeons who have already gained significant experience in the field of microsurgery.

Hybrid total alloplastic temporomandibular joint replacement prosthesis: a pilot study to evaluate feasibility, functional performance and impact on post-operative quality of life

PURPOSE

The aim of the present study was to investigate the clinical efficiency of hybrid alloplastic temporomandibular joint (TMJ) prosthesis in patients undergoing TMJ total alloplastic joint replacement (TMJR). The prosthesis utilized for this study for TMJR is a hybrid variant with combination of stock prototype design and a partial customization of components.

MATERIALS AND METHODS

A prospective clinical study was conducted involving five patients with unilateral TMJ ankylosis or end-stage joint disease (ESJD) indicated for and requiring TMJR. The patients underwent resection of the joint or gap arthroplasty followed by TMJR using the hybrid alloplastic TMJ prosthesis. The subjective and objective variables that included the jaw function (JF), inter-incisal opening (IO), diet intake (DI) and quality of life (QoL) were assessed using the psychometric modified Likert scale. The nutritional status of the patients was evaluated using the mid-upper arm circumference (MUAC) as reference.

RESULTS

The assessed study variables demonstrated functional and observational improvement in the post-operative follow-up when compared to the pre-operative period. The patients showed an improvement in overall QoL and nutritional status post-operatively. The follow-up period showed subjective and objective improvement in the parameters assessed among the study population.

CONCLUSION

There is a technical and clinical feasibility to utilize the hybrid alloplastic TMJ prosthesis as a reliable alloplastic option for treating patients requiring TMJR, with prudent indications.

Antibiotic prophylaxis in alloplastic temporomandibular joint replacement surgery: A multi-national survey of temporomandibular joint surgeons

Temporomandibular disorders include a wide spectrum of extra-articular and intra-articular conditions affecting the temporomandibular joint (TMJ). In salvage cases involving intra-articular end-stage disease, alloplastic temporomandibular joint replacement (TMJR) is a management option which can be utilised to rehabilitate a disabled joint's function and form. Whilst post-TMJR infection is rare, it is one of the most serious complications. The principles governing TMJR surgery antibiotic prophylaxis have been based on those established in orthopaedic surgery literature. Antibiotic resistance due to antibiotic over-use is a significant concern, therefore antibiotic stewardship has been developed to deal with this world-wide public health concern. The TMJ's anatomical proximity to the external auditory canal and oral cavity creates the potential for bacterial contamination. The aim of this study was to explore the views of 39 sub-specialist TMJ surgeons across nine nations usual approach to antibiotic prophylaxis and their management of TMJR infection. To accomplish this, an international survey was developed and conducted using Google Forms. The results demonstrated that 97.4% of the respondents employ prophylactic antibiotics at TMJR surgery, 83.8% on discharge. Variability in antibiotic choice with additional antimicrobial perioperative practices were also reported. Opinions on the management of a TMJR infection also varied. This survey establishes there is an agreement on the use of antibiotic prophylaxis, However the variability in choice, timing, course, duration of antibiotic use as well as the management of a postoperative TMJR infection demonstrates the need for further study leading to development of standardised antibiotic prophylaxis and infection management protocols for TMJR surgery.

Treatment of late-onset temporomandibular joint prosthesis infection by prosthesis revision: a case report

Late-onset infection of an inserted temporomandibular joint prosthesis is a difficult complication to treat. Most treatment protocols for late prosthetic infections include device replacement. A 40-year-old female patient with an infected and exposed temporomandibular joint prosthesis presented 3 years after implant placement. The patient was treated with prosthesis revision including fistula coverage with a temporalis muscle flap and prolonged antibiotic therapy for 10 weeks. Since completion of treatment, the patient has been infection-free.

Utilization of extended temporomandibular joint replacements in patients with hemifacial microsomia

Hemifacial microsomia (HFM) patients may benefit from extended temporomandibular joint replacements (eTMJR) to improve function and quality of life. A cross-sectional survey was sent to surgeons who place alloplastic temporomandibular joints regarding their experience with and complications encountered when placing eTMJR in patients with HFM. Fifty-nine responded to the survey. Thirty-six (61.0%) reported treating patients with HFM and 30 (50.8%) of those reported placing an alloplastic temporomandibular joint (TMJ) prosthesis for patients with HFM. Twenty-three of the 30 surgeons (76.7%) placing alloplastic TMJ prostheses reported using an eTMJR in patients with HFM. The average maximum inter-incisal opening (MIO) after an eTMJR in HFM patients was repor ted as> 25 mm by 82.6% of the participants, and between 16 mm and 25 mm by 17.4%. No participants reported MIO < 15 mm. To avoid condylar sag and open bite changes postoperatively, over 70% reported using some form of modification to stabilize the occlusion. Respondents reported good functional outcomes for eTMJR in patients with HFM with relatively few complications. Therefore, eTMJR could be considered a viable option in the management of this patient population.

Management of Intraoperative Contamination of the Custom Total Temporomandibular Joint Prosthesis

Management of intraoperative contamination of a custom total temporomandibular joint prosthesis has not been reported in the literature. As this complication is rare, it can be unsettling for the surgeon. Improper management may lead to a complicated treatment course and financial consequences. Prevention is the primary strategy for avoidance and appropriate management is dependent on many variables. The purpose of this report is to identify a unique complication associated with placement of a custom temporomandibular joint prosthesis and offer an algorithm for management.

Reconstruction of the TMJ and condyle in inflammatory arthritis

Inflammatory arthritis presents a unique destructive process to the temporomandibular joint. This article provides information on the proper diagnosis, treatment planning, and surgical management aimed to provide patients with improvement in pain, function, stability and facial aesthetics. Additionally, it aims to provide a detailed insight on the joint reconstruction options including alloplastic joint replacement, autogenous joint replacement, orthognathic surgery and distraction osteogenesis.

Antimicrobial Prophylaxis in Neonates and Children Undergoing Dental, Maxillo-Facial or Ear-Nose-Throat (ENT) Surgery: A RAND/UCLA Appropriateness Method Consensus Study

Surgical site infections (SSIs) represent a potential complication in surgical procedures, mainly because clean/contaminated surgery involves organs that are normally colonized by bacteria. Dental, maxillo-facial and ear-nose-throat (ENT) surgeries are among those that carry a risk of SSIs because the mouth and the first respiratory tracts are normally colonized by a bacterial flora. The aim of this consensus document was to provide clinicians with recommendations on surgical antimicrobial prophylaxis in neonates (<28 days of chronological age) and pediatric patients (within the age range of 29 days−18 years) undergoing dental, maxillo-facial or ENT surgical procedures. These included: (1) dental surgery; (2) maxilla-facial surgery following trauma with fracture; (3) temporo-mandibular surgery; (4) cleft palate and cleft lip repair; (5) ear surgery; (6) endoscopic paranasal cavity surgery and septoplasty; (7) clean head and neck surgery; (8) clean/contaminated head and neck surgery and (9) tonsillectomy and adenoidectomy. Due to the lack of pediatric data for the majority of dental, maxillo-facial and ENT surgeries and the fact that the recommendations for adults are currently used, there is a need for ad hoc studies to be rapidly planned for the most deficient areas. This seems even more urgent for interventions such as those involving the first airways since the different composition of the respiratory microbiota in children compared to adults implies the possibility that surgical antibiotic prophylaxis schemes that are ideal for adults may not be equally effective in children.

Reasons for failure of total temporomandibular joint replacement: a systematic review and meta-analysis

The aim of this study was to evaluate the revision rate after total alloplastic temporomandibular joint replacement (TMJR) and determine whether there is a higher risk of revision surgery with stock or custom-fitted prostheses (the two most current TMJR prosthesis types). A systematic review was performed, with a search of PubMed, Google Scholar, and the Cochrane Library in November 2020. Overall, 27 articles were included in this study, describing Biomet and TMJ Concepts prostheses and including postoperative data on complications requiring a return to the operating room. A total of 2247 prostheses were analysed: 1350 stock Biomet prostheses and 897 custom-fitted TMJ Concepts and custom-fitted Biomet prostheses. The global revision rate was 1.19 per 100 prosthesis-years. The most common reason for revision was heterotopic bone formation. Stock prostheses appeared to have a lower risk of revision compared to custom prostheses: rate ratio 0.52 (95% confidence interval 0.33-0.81, P-value 0.003). Regarding causes of revision, the only significant difference between the types of devices was a higher rate of heterotopic bone formation for custom-made prostheses (P = 0.001). The results of this study revealed a low revision rate post TMJR revision, with stock devices even less prone to such risk. Nevertheless, these results can be explained by the fact that custom-made prostheses are more likely to be used for cases in which the anatomy is significantly abnormal or there is a history of multiple joint surgeries, which carry a greater risk of complications and heterotopic bone formation.

Imaging of the Postoperative Jaws and Temporomandibular Joints

Surgical procedures in the oral cavity and maxillofacial complex are diverse and involve multiple tissues unique to this region. These procedures are used to remove pathology and infection, restore function, optimize occlusal relationships, prosthetically replace teeth and temporomandibular joints, improve esthetics, and increase upper respiratory tract dimensions. Procedures in the oral cavity are often complicated by infection stemming from the naturally occurring oral flora, but can also be complicated iatrogenically. This article explores the more commonly encountered surgical procedures through examination of the indications, anatomy to consider, and the radiographic imaging of success and failure of these procedures.

Current Concepts in Prophylactic Antibiotics in Oral and Maxillofacial Surgery

Antibiotic prophylaxis is the use of antibiotics in the perioperative period to prevent surgical site infections from local flora. Specific guidelines and criteria exist to prevent these infections while also practicing antimicrobial stewardship. Most dentoalveolar procedures do not require antibiotic prophylaxis. For nondentoalveolar procedures, the decision to provide antibiotic prophylaxis is based on involvement of the respiratory, oral, or pharyngeal mucosa. Special considerations exist for patients at high risk for infective endocarditis, patients with head and neck cancer, and temporomandibular joint replacement procedures. This article discusses indications for antibiotic prophylaxis during oral and maxillofacial surgical procedures.

Total Temporomandibular Joint Replacement and Simultaneous Orthognathic Surgery Using Computer-Assisted Surgery

Background

Disorders of the temporomandibular joint (TMJ) are frequent and are usually associated with other disorders of the facial skeleton. Surgery might be needed to correct TMJ anatomy and function and, in cases where pathologies coexist, a two-stage corrective surgery might be needed. However, the current fashion of single-stage procedures is feasible with the aid of new technologies such as computer-assisted surgery (CAS). This is a step forward toward performing complex procedures such as a TMJ replacement with simultaneous orthognathic surgery. CAS allows designing patient-fitted prosthesis and more predictable and accurate surgeries. Moreover, intraoperative development can be controlled in real time with intraoperative navigation, and postoperative results can be measured and compared afterwards.

Aims

The primary purpose of this article is to present the protocol used in our institution for orthognathic surgery associated with unilateral and bilateral TMJ replacement with patient-fitted prostheses guided with CAS.

Materials and methods

We present two cases to illustrate our protocol and its results.

Results

In the first case, the difference in millimeters between planning and surgical outcomes was 1.72 mm for the glenoid component and 2.16 mm for the condylar prosthesis; for the second case, differences in the right side were 2.59 mm for the glenoid component and 2.06 mm for the ramus, and in the left side, due to the anatomy the difference was a little greater, without clinical significance.

Conclusion

Combined surgery of the midface and mandible with total TMJ replacement is feasible and beneficial for the patient. CAS facilitates the planning and design of custom-fit prosthesis and execution of these procedures.

Digitally designed, personalized bone cement spacer for staged TMJ and mandibular reconstruction - Introduction of a new technique

The aim of this paper is to introduce an innovative workflow for staged reconstruction of the mandible, including the temporomandibular joint (TMJ), using a temporary, patient-specific spacer. In cases of partial mandibular resection including disarticulation, sometimes needed to treat inflammatory bone disease, the spacer is intended to retain symmetry of the hard tissues, to preserve the soft tissues, and to act as a bactericidal agent. When complete healing of the affected surrounding tissues has occurred, final reconstruction using a patient-matched total TMJ endoprosthesis, in combination with an autogenous free bone flap, can be performed as a second-stage procedure. The crucial steps of the workflow are virtual surgical planning, manufacturing of a two-part silicone mold, and chairside manufacturing of the spacer using an established bone cement with gentamycin. The method was first introduced in two patients suffering from therapy-resistant chronic osteomyelitis. The presented protocol of staged surgery allows a much safer and predictable reconstruction compared with immediate reconstruction. The workflow also minimizes the potential risk of endoprosthesis infection - one of the major risks of implant failure.

Temporomandibular joint reconstruction with medial femoral condyle osseocartilaginous flap: a case series

Reconstruction for large-scale temporomandibular joint (TMJ) defects can be challenging. We have used the medial femoral condyle (MFC) osseocartilaginous flap for repair of TMJ defects. The aim of this paper was to describe our technique and to present the preliminary results. The MFC osseocartilaginous flap was used as a free vascularized graft for TMJ defect in four patients who had undergone resection for benign tumor of the TMJ region (n = 2) or TMJ ankylosis (n=2). A computer-assisted technique was used in all cases. Symmetry of the mandible was objectively evaluated by postoperative computed tomography. Complications were recorded during follow-up visits. Lower extremity functional status was assessed by the Lower Extremity Functional Scale (LEFC) questionnaire. The MFC osseocartilaginous flap success rate was 100%; bony union was obtained in all four patients, and normal occlusion was achieved within 6-11 months after surgery. No flap-related complications occurred. All patients were satisfied with their postoperative facial symmetry and oral function. The LEFC score ranged from 72 to 80, indicating normal lower extremity function. Vascularized MFC osseocartilaginous flap appears to be a reliable option for reconstruction of large-scale TMJ defects.

Antibiotic prophylaxis in oral and maxillofacial surgery: a systematic review

Surgical site infections are a complication of oral and maxillofacial procedures, with the potential for significant morbidity and mortality. Use of preoperative, perioperative, and postoperative antibiotic prophylaxis to reduce the incidence of surgical site infections must be balanced with considerations of a patients' risk of antibiotic-related adverse events. This review aimed to provide evidence-based recommendations for antibiotic prophylaxis. Searches were conducted using MEDLINE, the Cochrane Library, EMBASE, and PUBMED for maxillofacial procedures including: treatment of dental abscesses, extractions, implants, trauma, temporomandibular joints, orthognathics, malignant and benign tumour removal, and bone grafting, limited to articles published since 2000. A total of 98 out of 280 retrieved papers were included in the final analysis. Systematic reviews were assessed using AMSTAR criteria. Randomised controlled trials were assessed for bias using Cochrane Collaborative tools. The overall quality of evidence was assessed using GRADE. Prophylactic antibiotic use is recommended in surgical extractions of third molars, comminuted mandibular fractures, temporomandibular joint replacements, clean-contaminated tumour removal, and complex implants. Prophylactic antibiotic use is not routinely recommended in fractures of the upper or midface facial thirds. Further research is required to provide recommendations in orthognathic, cleft lip, palate, temporomandibular joint surgery, and maxillofacial surgical procedures in medically-compromised patients.

Total temporomandibular joint replacement without a submandibular incision

Temporomandibular joint replacement is a well-accepted and successful treatment option for advanced pathology of the temporomandibular joint. There are however a number of complications associated with the procedure such as post-operative infection, facial nerve damage and scarring. Total joint replacement has traditionally involved the use of both a pre-auricular and submandibular incision. We present an approach that uses only a pre-auricular incision without the need for a submandibular incision. This approach is less invasive and has the potential to decrease risk of damage to the marginal mandibular branch of facial nerve and scarring of the neck.

Advancements in temporomandibular joint total joint replacements (TMJR)

The goal of this paper is to review the advantages and disadvantages of the various treatment options of temporomandibular joint (TMJ) total joint replacement (TJR). TMJ articles published within the last 20 years were reviewed to collect the information on non-invasive and invasive TMD treatment methods. Recent technological advancements helped the evolution of treatment methods and offered significant value to TMD patients and surgeons. Considering the TMD levels, the therapeutic procedures can involve general health examiniations, physical therapy, medication, oral rehabilation or as an end stage clinical invention, temporomandibular joint replacement. In fact when intra-articular TMD is present, the effective treatment method appears to be TJR. However, concern for infection, material hypersensitivity, device longevity and screws loosening issues still exists. Further combined research utilizing the knowledge and expertise of, surgeons, material scientists, and bioengineers is needed for the development of improved TMD therapeutic treatment.

Prevention and detection of prosthetic temporomandibular joint infections-update

Prosthetic joint infections are not only distressing complications for patients and surgeons, but also have an enormous financial impact on healthcare systems. The reported incidence of prosthetic joint infection is likely underestimated due to difficulties in their diagnosis. This unfortunate complication has challenged joint replacement surgeons for years, despite all the advances made in this surgical discipline. Since eradication of these infections can be very difficult, prevention remains the primary objective. Identifying recipient risk factors, adopting a proper surgical technique, appropriate wound care, optimizing the operating room environment, and appropriate postoperative care have become some of the core elements that can help to minimize the overall incidence of this complication. The purpose of this article is to provide the temporomandibular joint replacement surgeon with an update on the prevention and detection of prosthetic joint infections based on a review of the most recent information published in the orthopedic and surgical literature.

Temporomandibular joint reconstruction

PURPOSE OF REVIEW

Temporomandibular joint (TMJ) reconstruction represents one of the more challenging clinical problems that a head and neck surgeon encounters. Fortunately, the problem is fairly uncommon; however, at the same time, clear clinical guidelines have not been formulated. The goal of this review is to present the established solutions to this difficult reconstructive challenge and highlight key developments that have been recently published.

RECENT FINDINGS

Modern-day approaches to TMJ reconstruction include a handful of surgical modalities: costochondral grafting, revascularized tissue transfer, distraction osteogenesis, and alloplastic temporomandibular joint replacement (APTMJR). Over the past several years, publications have focused primarily on distraction osteogenesis and APTMJR. In particular, APTMJR is emerging as a highly successful and versatile surgical modality when faced with TMJ defects.

SUMMARY

With long-term follow-up after APTMJR approaching 20 years at several of the pioneering centers, alloplastic total joint replacement is emerging as the clinical standard when faced with TMJ defects in a variety of clinical situations. Unfortunately, the dogma of serious complications that occurred during early development may still be stalling widespread acceptance of APTMJR. Due to the complexity of the surgery, its relative infrequency and the lack of exposure in the majority of residency training programs, this surgery is currently best performed by tertiary referral centers.

Potential Indications for Tissue Engineering in Temporomandibular Joint Surgery

PURPOSE

Musculoskeletal tissue engineering has advanced to the stage where it has the capability to engineer temporomandibular joint (TMJ) anatomic components. Unfortunately, there is a paucity of literature identifying specific indications for the use of TMJ tissue engineering solutions. The objective of this study was to establish an initial set of indications and contraindications for the use of engineered tissues for replacement of TMJ anatomic components.

FINDINGS

There was consensus among the authors that the management of patients requiring TMJ reconstruction as the result of 1) irreparable condylar trauma, 2) developmental or acquired TMJ pathology in skeletally immature patients, 3) hyperplasia, and 4) documented metal hypersensitivities could be indications for bioengineered condyle and ramus TMJ components. There was consensus that Wilkes stage III internal derangement might be an indication for use of a bioengineered TMJ disc or possibly even a disc-like bioengineered "fossa liner." However, there was some controversy as to whether TMJ arthritic disease (e.g., osteoarthritis) and reconstruction after failed alloplastic devices should be indications. Further research is required to determine whether tissue-engineered TMJ components could be a viable option for such cases. Contraindications for the use of bioengineered TMJ components could include patients with TMJ disorders and multiple failed surgeries, parafunctional oral habits, persistent TMJ infection, TMJ rheumatoid arthritis, and ankylosis unless the underlying pathology can be resolved.

CONCLUSIONS

Biomedical engineers must appreciate the specific indications that might warrant TMJ bioengineered structures, so that they avoid developing technologies in search of problems that might not exist for patients and clinicians. Instead, they should focus on identifying and understanding the problems that need resolution and then tailor technologies to address those specific situations. The aforementioned indications and contraindications are designed to serve as a guide to the next generation of tissue engineers in their strategic development of technologies to address specific clinical issues.

Prosthesis Loading After Temporomandibular Joint Replacement Surgery: A Musculoskeletal Modeling Study

One of the most widely reported complications associated with temporomandibular joint (TMJ) prosthetic total joint replacement (TJR) surgery is condylar component screw loosening and instability. The objective of this study was to develop a musculoskeletal model of the human jaw to assess the influence of prosthetic condylar component orientation and screw placement on condylar component loading during mastication. A three-dimensional model of the jaw comprising the maxilla, mandible, masticatory muscles, articular cartilage, and articular disks was developed. Simulations of mastication and a maximum force bite were performed for the natural TMJ and the TMJ after prosthetic TJR surgery, including cases for mastication where the condylar component was rotated anteriorly by 0 deg, 5 deg, 10 deg, and 15 deg. Three clinically significant screw configurations were investigated: a complete, posterior, and minimal-posterior screw (MPS) configuration. Increases in condylar anterior rotation led to an increase in prosthetic condylar component contact stresses and substantial increases in condylar component screw stresses. The use of more screws in condylar fixation reduced screw stress magnitudes and maximum condylar component stresses. Screws placed superiorly experienced higher stresses than those of all other condylar fixation screws. The results of the present study have important implication for the way in which prosthetic components are placed during TMJ prosthetic TJR surgery.

The use of prophylactic antibiotics prior to dental procedures in patients with prosthetic joints: Evidence-based clinical practice guideline for dental practitioners--a report of the American Dental Association Council on Scientific Affairs

BACKGROUND

A panel of experts (the 2014 Panel) convened by the American Dental Association Council on Scientific Affairs developed an evidence-based clinical practice guideline (CPG) on the use of prophylactic antibiotics in patients with prosthetic joints who are undergoing dental procedures. This CPG is intended to clarify the "Prevention of Orthopaedic Implant Infection in Patients Undergoing Dental Procedures: Evidence-based Guideline and Evidence Report," which was developed and published by the American Academy of Orthopaedic Surgeons and the American Dental Association (the 2012 Panel).

TYPES OF STUDIES REVIEWED

The 2014 Panel based the current CPG on literature search results and direct evidence contained in the comprehensive systematic review published by the 2012 Panel, as well as the results from an updated literature search. The 2014 Panel identified 4 case-control studies.

RESULTS

The 2014 Panel judged that the current best evidence failed to demonstrate an association between dental procedures and prosthetic joint infection (PJI). The 2014 Panel also presented information about antibiotic resistance, adverse drug reactions, and costs associated with prescribing antibiotics for PJI prophylaxis.

PRACTICAL IMPLICATIONS AND CONCLUSIONS

The 2014 Panel made the following clinical recommendation: In general, for patients with prosthetic joint implants, prophylactic antibiotics are not recommended prior to dental procedures to prevent prosthetic joint infection. The practitioner and patient should consider possible clinical circumstances that may suggest the presence of a significant medical risk in providing dental care without antibiotic prophylaxis, as well as the known risks of frequent or widespread antibiotic use. As part of the evidence-based approach to care, this clinical recommendation should be integrated with the practitioner's professional judgment and the patient's needs and preferences.

Late reconstruction of condylar neck and head fractures

Condyle fractures are a common injury, but only a few of these injuries require immediate or late reconstruction. The complications that most frequently necessitate condylar reconstruction include proximal segment degeneration, malunion, and ankylosis. Costochondral grafts and total joint prostheses, both stock and custom, remain the most common methods of reconstruction. Reconstruction plates with condylar extensions should only be used temporarily as an unacceptable number cause serious complications. Distraction osteogenesis may have an occasional role in reconstructing the posttraumatic condyle.