Extended total temporomandibular joint replacements: a classification system.

Prosthetic total temporomandibular joint (TMJ) replacement (TJR) is well established in the United Kingdom, with clear guidelines for indications and nationally published outcomes. CAD/CAM technology has made it possible to push the boundaries of custom-made TJR to include extended versions (eTJR), which may replace segmental mandibular defects or defects in the skull base with extended components for the ramus and fossa, respectively. Such prostheses are uncommon, and published reports are restricted to isolated cases and series of cases. We know of no previous attempts to classify such prostheses, and here we suggest a bipartite classification system for use in communications between surgeons and manufacturers based on a review of 19 prostheses provided by one manufacturer (TMJ Concepts, Ventura, CA).

[Masticatory system and maxillofacial prosthesis: From pathology to function recovering]. / Appareil manducateur et prothèse maxillo-faciale : de la pathologie à la fonction retrouvée.

Maxillofacial prosthesis (MFP) can be defined as the art and science of esthetic and functional reconstruction of the facial bones, art because it uses hand-crafted and empirical rules, science because of its technical rigorism and its integration in medicine. MFP aims to multidisciplinary rehabilitate patients presenting with cutaneous and underlying structures defects, It also allows for functional speech and swallowing rehabilitation related to temporo-mandibular joint disorders. Whatever the origin, (traumatic, infectious ortumoral), surgical treatment of these TMJ disorders is usually not indicated in first-line. Functional treatment is often sufficient if started early in an observant patient. The aim of our article was to present the different types devices available for the rehabilitation of the masticatory system according to pathology. The first part will treat about the preservation of the TMJ range of motion in a preventive way. A second part will treat about the possibilities to recover the range of motion in a curative way. A third part will treat about mandibular reposition. At last, we will focus on the devices allowing for mandibular kinetic rehabilitation in adults and in a special pediatric case.

Reverse Shoulder Arthroplasty Prosthesis Design Classification System.

Multiple different reverse total shoulder arthroplasty (rTSA) prosthesis designs are available in the global marketplace for surgeons to perform this growing procedure. Subtle differences in rTSA prosthesis design parameters have been shown to have significant biomechanical impact and clinical consequences. We propose an rTSA prosthesis design classification system to objectively identify and categorize different designs based upon their specific glenoid and humeral prosthetic characteristics for the purpose of standardizing nomenclature that will help the orthopaedic surgeon determine which combination of design configurations best suit a given clinical scenario. The impact of each prosthesis classification type on shoulder muscle length and deltoid wrapping are also described to illustrate how each prosthesis classification type impacts these biomechanical parameters.

The role of total elbow arthroplasty in traumatology.

UNLABELLED: Fractures of the distal humerus account for 5% of osteoporotic fractures in subjects older than 60 years. A history of osteoporosis, co-morbidities, and joint comminution make their management difficult. The therapeutic options are limited to functional treatments, osteosynthesis, or either partial or total arthroplasty. Functional treatment of distal humerus fractures in the elderly subject provide inconsistent results, often with persistence of pain with a stiff or unstable elbow. Osteosynthesis remains the reference treatment for these fractures, following the principle of stable and rigid osteosynthesis allowing early mobilization. However, joint comminution and a history of osteoporosis occasionally make it impossible to meet this objective, with a considerable rate of complications and surgical revisions. Total elbow arthroplasty remains an alternative to osteosynthesis with very satisfactory immediate results restoring a painless, stable, and functional elbow. These results seem reproducible and sustainable over time. The complication rate is not uncommon with an approximately 10% surgical revision rate. Elbow hemiarthroplasty remains to be validated in this indication. LEVEL OF EVIDENCE: V.

[Effect of sterilisation with formaldehyde, gamma irradiation and ethylene oxide on the properties of polyethylene joint replacement components]. / Vliv sterilizace formaldehydem, gama zárením a etylenoxidem na vlastnosti polyetylenových komponent kloubních náhrad.

PURPOSE OF THE STUDY: Each method of sterilisation has some effect on the structure and properties of UHMWPE and thus also on joint replacement longevity. This study was designed to compare, using objective methods of measurement, several kinds of sterilisation and to recommend the one which has the best prospect for making joint replacements last longer. MATERIAL AND METHODS: Two groups of UHMWPE samples were tested. Group 1 included virgin GUR 1020 polyethylene, non-modified and non-sterilised (Meditech, Germany). Group 2 comprised of three sets of samples sterilised with formaldehyde, gamma irradiation and ethylene oxide, respectively. In both groups, physicochemical properties were assessed by infrared spectroscopy (IR), and the oxidation (OI) and trans-vinyl (VI) indices, which show the degree of oxidation of a material, were determined. Free-radical concentrations were measured by the method of electron spin resonance (ESR). The mechanical properties of each sample were studied using small punch tests (SPT) and testing microhardness (MH). Any change in mechanical properties can affect, to various degrees, the quality and longevity of a prosthetic joint. RESULTS: The samples sterilised by gamma irradiation showed higher values of both the OI (0.37) and the VI index (0.038) than the other samples (OI, 0.02 to 0.05 and VI, 0). Also, the free-radical concentration was detectable only in the gamma-sterilised sample. Values obtained for mechanical properties were as follows: peak load in the range of 58.48 N (gamma irradiation) to 59.60 N (ethylene oxide); ultimate load in the range of 46.69 N (gamma irradiation) to 57.50 N (ethylene oxide); ultimate displacement in the range of 4.29 mm (gamma irradiation) to 4.58 mm (virgin polyethylene and formaldehyde); and work to failure in the range of 185.18 mJ (gamma irradiation) to 205.89 mJ (virgin polyethylene). Microhardness values were obtained in the following ranges: 41.2 to 44.6 MPa (virgin polyethylene); 40.2 to 44.1 MPa (formaldehyde); 46.1 to 49.3 MPa (gamma irradiation); and 40.3 to 44.2 MPa (ethylene oxide). DISCUSSION: The samples sterilised with formaldehyde and ethylene oxide have mechanical properties very similar to virgin polyethylene, they are not damaged by oxidation and do not contain free radicals. Owing to these characteristics, the immediate and long-term oxidation stability of the three samples is higher. The sample sterilised by gamma irradiation showed the presence of free radicals and immediate and long-term oxidative degradation. This results in the deterioration of mechanical properties and the growth of crystallinity due to enhanced oxidation and leads to higher polyethylene microhardness. CONCLUSIONS: Sterilisation with gamma irradiation results in oxidative degradation and mechanical property deterioration, which is one of the potential risks of a shorter life span of joint replacements. The use of ethylene oxide or formaldehyde does not change polymer properties nor has any effect on oxidation of materials. Therefore, a longer life expectancy of the joint replacements sterilised with ethylene oxide can be expected. The life span of their joint replacements is a key issue for the patients. Prosthetic joint loosening is painful and the patient often requires re-implantation. A higher number of re-implantations is associated with higher costs for the institution involved and, consequently, for the whole health care system. Although this study basically deals with chemical issues, it informs the surgeon of the latest developments leading to the improvement of implanted materials, which can increase the life expectancy of joint replacements and patients' satisfaction.

UK temporomandibular joint replacement database: report on baseline data.

Our goal is to establish the long-term collection of data on temporomandibular joint replacement from all centres in the UK where this is done. Currently, 16 surgeons have been identified, and 13 of them had entered data when this paper was being prepared. Data are entered online through the Snap Survey and then analysed annually. We report on 402 patients (332 (83%) female and 70 (17%) male) who had 577 joints inserted between 1994 and 2012. The main diagnoses that resulted in total joint replacement were osteoarthritis, failed operation, ankylosis, and seronegative arthritis. Preoperatively, the median (IQR) maximal incisal opening was 20 (15-26)mm (mean 20) and the median pain scores on the visual analogue scale (VAS 0-10) were 8 for both joints. The median (IQR) baseline dietary score (liquid 0 - solid 10) was 4 (3-6). A total of 173 (43%) patients had had one or more open procedure(s) before total replacement, 177 (44%) had not had open operation, and 52 (13%) had no data entered. The 3 primary systems used were the TMJ Concepts System (Ventura, USA), the Biomet System (Biomet/Lorenz Microfixation, Jacksonville, USA), and the Christensen System (TMJ Implants, Golden, USA). The median (IQR) duration of inpatient stay was 3 (2-4) days (mean 3). Follow-up data will be collected to assess patient recorded outcome measures (PROM) and objective measurements of total joint replacements in the UK from 1994 onwards.

A classification of growth friendly spine implants.

BACKGROUND: Various types of spinal implants have been used with the objective of minimizing spinal deformities while maximizing the spine and thoracic growth in a growing child with a spinal deformity. PURPOSE: The aim of this study was to describe a classification system of growth friendly spinal implants to allow researchers and clinicians to have a common language and facilitate comparative studies. Growth friendly spinal implant systems fall into 3 categories based upon the forces of correction the implants exert on the spine, which are as follows: Distraction-based systems correct spinal deformities by mechanically applying a distractive force across a deformed segment with anchors at the top and bottom of the implants, which commonly attach to the spine, rib, and/or the pelvis. The present examples of distraction-based implants are spine-based or rib-based growing rods, vertical expandable titanium rib prosthesis, and remotely expandable devices. Compression-based systems correct spinal deformities with a compressive force applied to the convexity of the curve causing convex growth inhibition. This compressive force may be generated both mechanically at the time of implantation, as well as over time resulting from longitudinal growth of vertebral endplates hindered by the spinal implants. Examples of compression-based systems are vertebral staples and tethers. Guided growth systems correct spinal deformity by anchoring multiple vertebrae (usually including the apical vertebrae) to rods with mechanical forces including translation at the time of the initial implant. The majority of the anchors are not rigidly attached to the rods, thus permitting longitudinal growth over time as the anchors slide over the rods. Examples of guided growth systems include the Luque trolley and Shilla. CONCLUSIONS: Each system has its benefits and shortcomings. Knowledge of the fundamental principles upon which these systems are based may aid the clinician to choose an appropriate treatment for patients. Having a common language for these systems may aid in comparative research. Vertical expandable titanium rib prosthesis is used with humanitarian exemption. The other devices mentioned in this manuscript are not approved for growing constructs by the Food and Drug Administration and are used off-label.

A ten-year experience and follow-up of three hundred patients fitted with the Biomet/Lorenz Microfixation TMJ replacement system.

The purpose of this paper is to present the postoperative results obtained after full temporomandibular joint (TMJ) reconstruction employing the Biomet/Lorenz Microfixation TMJ replacement system (Jacksonville, FL, USA) in 300 patients (201 unilateral, 99 bilateral). Objective data (maximum inter-incisal opening; MIO) and subjective data (function and speech, diet, and pain) were collected preoperatively and at postoperative evaluations performed over a 10-year period (mean 3.5, standard deviation 2.1 years). The MIO measures were obtained using a calliper rule. Subjective data were evaluated using a visual analogue scale with scores ranging from 0 to 5 for each variable. The results were analyzed with the paired t-test (two-sided, α=5%). Each patient showed significant improvements for all of the variables at evaluation on postoperative day 7. The results for MIO, function and speech, and diet, showed improvements at each postoperative evaluation over a maximum of 3 years, with stabilization of the results from the fourth year. Complaints of pain decreased considerably up to the 1-month postoperative evaluation, and no patient reported severe pain at 6 months after surgery. The results presented show that the reconstruction of the TMJ through the installation of the Biomet/Lorenz system prosthesis is a safe and effective option for proper reestablishment of the joint and stomatognathic system function; significant long-term improvements in mandibular range of motion are promoted and pain levels decrease.

The use of an eccentric glenosphere compared with a concentric glenosphere in reverse total shoulder arthroplasty: two-year minimum follow-up results.

PURPOSE: The current models of reverse shoulder arthroplasty (RSA) expose the procedure to the risk of scapular notching, possibly leading to loosening of the glenoid. We compared the clinical and radiographic results obtained with a concentric or eccentric glenosphere to assess whether the eccentric design might give better clinical results and avoid or decrease the risk of scapular notching METHODS: Of our patients, 31 underwent RSA using a concentric glenosphere (group A), while 29 had an eccentric glenosphere (group B). Postoperatively, patients were followed-up at one to 12 months and annually thereafter, with the mean being 33 months in group A and 27.5 in group B. In both groups the minimum follow up (F-U) was 24 months. Preoperatively and at each F-U starting from six months, patients were assessed using the Constant score. On radiographs, prosthesis scapular neck angle (PSNA), distance between scapular neck and glenosphere (DBSNG) and peg-glenoid rim distance (PGRD) were calculated. The severity of notching was classified in four grades. RESULTS: In group A the mean Constant score increased by 30 points compared to the preoperative score and the active ROM increased considerably. At latest F-U, the mean PSNA, DBSNG and PGRD were, respectively, 87°, 3.4 mm and 19.8 mm. Glenoid notching was present in 42% of cases. In group A, the mean Constant score increased by 34 points and the mean ROM was better than in group A. The average PSNA, PGRD and DBSNG were, respectively, 92°, 21.2 mm and 4.3 mm. Radiographs showed no inferior scapular notching. CONCLUSIONS: The eccentric glenosphere yielded better clinical results than the concentric glenosphere and was associated with no scapular notching.

Shoulder arthroplasty. Part 1: Prosthesis terminology and classification.

Shoulder arthroplasty is the third most common joint replacement procedure in the UK, and there are a number of different implant options available to surgeons to treat a variety of shoulder disorders. With an increasing burden placed on clinical follow-up, more patients are remaining under the care of their general practitioners and musculoskeletal triage assessment services and are not necessarily being seen by specialists. Referrals to orthopaedic specialists are therefore often prompted by radiological reports describing evidence of implant failure. This article is the first of two reviews on shoulder arthroplasty, concentrating on implant features and the indications for their use. The second article will address the modes of failure of shoulder arthroplasty and describe the relevant associated radiological features.

Challenges in prosthesis classification.

Accurate prosthesis classification is critical for total joint arthroplasty surveillance and assessment of comparative effectiveness. Historically, prosthesis classification was based solely on the names of the prosthesis manufacturers. As a result, prosthesis designs changed without corresponding name changes, and other prostheses' names changed over time without substantial design modifications. As the number of prostheses used in total joint arthroplasty on the market increased, catalog and lot numbers associated with prosthesis descriptions were introduced by manufacturers. Currently, these catalog and lot numbers are not standardized, and there is no consensus on categorization of these numbers into brands or subbrands. Classification of the attributes of a prosthesis also varies, limiting comparisons of prostheses across studies and reports. The development of a universal prosthesis classification system would standardize prosthesis classification and enhance total joint arthroplasty research collaboration worldwide. This is a current area of focus for the International Consortium of Orthopaedic Registries (ICOR).

Difference in occurrence of heterotopic ossification according to prosthesis type in the cervical artificial disc replacement.

STUDY DESIGN: Retrospective study of the difference of heterotopic ossification (HO) occurrence according to 3 different types of prosthesis. OBJECTIVE: This study was designed to investigate the difference of HO occurrence according to different type of prosthesis. SUMMARY OF BACKGROUND DATA: HO is defined as formation of the bone outside the skeletal system. Reported HO occurrence rate in cervical artificial disc replacement (ADR) was unexpectedly high and varied. But the influencing factors of HO in cervical ADR have not been elucidated well. The prosthesis-related factors for making difference of HO occurrence were investigated in this study. METHODS: A total of 170 patients undergoing cervical arthroplasty with the Bryan cervical disc prosthesis (Medtroic Sofamor Danek, Memphis, TN), Mobi-C disc prosthesis (LDR Medical, Troyes, France), and ProDisc-C (Synthes, Inc., West Chester, PA) were included. Cervical lateral radiographs obtained before and after surgery were used to identify HO. Occurrence rate, occurrence-free period, location, and grade of HOs were investigated according to the different prosthesis. RESULTS: Each prosthesis group included patients as follows: Bryan disc, 81 patients; Mobi-C, 61 patients; and ProDisc-C, 28 patients. Overall HO rate was 40.6% (69 of 170 patients). Each HO occurrence rate by prosthesis was as follows: the Bryan disc group, 21.0%; Mobi-C group, 52.5%; and the ProDisc-C group, 71.4%. In the survival analysis, all patients showed 27.1 +/- 3.7 months as the median survival. The Bryan disc group showed statistically longer survival (48.4 +/- 7.4 months) than the other groups. CONCLUSION: Occurrence of HO is an inevitable postoperative complication after cervical ADR. The occurrence rate of HO was higher than our expectation. Moreover, definite differences in occurrence rate according to the prosthesis type were identified by this study.

Temporomandibular joint total replacement prosthesis: current knowledge and considerations for the future.

This paper provides a review of the current knowledge of temporomandibular joint total replacement systems. An electronic Medline search was performed to identify all the relevant English-language, peer-reviewed articles published during 1990-2006. Twenty-eight references were considered for review, seven of which were reviews, 17 clinical trials or case series, and four single-patient case reports. Therapeutic outcomes were encouraging for all three total prosthetic systems for which follow-up data from a consistent sample of patients exist. A lack of homogeneity between studies in patient selection and indications for the intervention was noted. A better integration between clinical and research settings is needed to achieve a standardized definition of the rationale and indications for total temporomandibular joint replacement. Findings from the available studies are promising, and need to be confirmed by multicenter trials taking into account interoperator variability.

The effect of metallic radial head arthroplasty on radiocapitellar joint contact area.

OBJECTIVE: This study determined the effect of metallic radial head arthroplasty on radiocapitellar joint contact area. DESIGN: The contact area of eight intact radiocapitellar joints was assessed during simulated compressive loading. Subsequently, the same experiments were repeated after reconstruction with three different radial head implant sizes. BACKGROUND: There has been an increasing use of metal radial head implants relative to silicone implants. However, the contact characteristics with the metal reconstruction have not been determined. METHODS: A 100 N compressive load was applied to the radiocapitellar joint at three different flexion angles for the native joint and three different sizes of a metal head implant. An impression material was employed to quantify joint contact area. RESULTS: Following metallic radial head arthroplasty, the contact area decreased by approximately two-thirds relative to the native radiocapitellar joint (P<0.001). Smaller implant sizes resulted in slightly larger contact areas (P<0.05). In addition, contact area decreased as joint flexion angle increased (P<0.04). CONCLUSIONS: Selection of radial head implant size is likely not a significant factor with regard to contact area mechanics of the radiocapitellar articulation. RELEVANCE: The effect of radial head implant size on the contact area produced with the native capitellum is not known. This study shows that the design or selection of a metallic radial head implant from the viewpoint of size is likely not an important factor with regard to minimizing joint contact stresses.

Intrinsic stability of an unconstrained metacarpophalangeal joint implant.

OBJECTIVE: To compare the intrinsic stability of an unconstrained resurfacing metacarpophalangeal arthroplasty to that of a normal human cadaveric joint. DESIGN: Cadaveric joints and metacarpophalangeal prostheses were studied in a mechanical testing machine at different angles and axial loads to determine the stability ratio in eight directions of movement. BACKGROUND: An unconstrained resurfacing arthroplasty was designed to replicate the normal anatomy with the exception of the proximal component having a greater arc of curvature on its dorsal aspect. METHODS: Eight fresh-frozen cadaveric joints and five different sizes of the AVANTA metacarpophalangeal prosthesis were studied at 0 degrees, 45 degrees and 90 degrees angles of flexion and at eight different directions of motion with three different axial loads (0, 20, 40 N). A 6-component load cell measured the force needed to sublux the joint. The stability ratio was the measured outcome and is defined as ratio of the force of subluxation to the axial force. RESULTS AND CONCLUSIONS: The unconstrained resurfacing arthroplasty has more intrinsic stability than the cadaveric metacarpophalangeal joint in all eight directions tested. RELEVANCE: A major complication of metacarpophalangeal implants is ulnopalmar subluxation. The AVANTA implant is designed to decrease the risk of ulnopalmar subluxation by having a greater arc of curvature on the dorsal aspect of the proximal component. This study shows that the designed implant has greater stability due to the geometry of the implant compared to that of the anatomical joint.

Localization and diagnosis of septic endoprosthesis infection by using 99mTc-HMPAO labelled leucocytes.

The aim of this study was to evaluate, retrospectively, the diagnostic value of Tc hexamethylpropylene amine oxime (99mTc-HMPAO) labelled autologous leucocytes for the preferred septic localizations of the infection of the endoprosthesis. We retrospectively reviewed 67 patients with implanted endoprostheses. Diagnosis was found in 42/67 patients. In 25/67 patients we were able to negate an acute pathological process of infection of the endoprosthesis. Our patients were divided into three groups according to the type of endoprosthesis (hip joint, knee joint, shoulder joint). The localizations of the endoprosthesis disorders are shown. The preferred localizations of the acute infection of the hip endoprosthesis are the regio intertrochanterica and the middle part of the shaft of the prosthesis. The preferred localization of the acute infection of the knee endoprosthesis is the proximal shaft of the tibia. The preferred localization of the acute infection of the shoulder endoprosthesis is the distal end of the prosthesis in the proximal humerus. It is hoped that the knowledge of these preferred localizations of infection of endoprosthesis will help patients and doctors in diagnosis and treatment in the future.

Retrieved glenoid components: a classification system for surface damage analysis.

There have been many reports describing modes of damage in retrieved total hip and total knee arthroplasty components. The most common mechanism in total hip arthroplasties has been shown to be surface wear. Fatigue failure shown as pitting and delamination are observed more often in total knee components. There has been no previous analysis of retrieved polyethylene glenoid components. This study evaluated the wear mechanisms contributing to failure of total shoulder glenoid components. Polyethylene glenoid components from 10 consecutive total shoulder arthroplasties have been retrieved and analyzed. Wear mechanisms were analyzed under low-power magnification, and a classification system was designed for total shoulder arthroplasties. This classification system is an adaptation of previous models of hip and knee surface damage. The severity of each damage mode was graded in 4 separate quadrants. The most prevalent damage modes were abrasion, pitting, and delamination. These data show a combination of abrasive wear and fatigue in retrieved total shoulder specimens. Surface wear and subsurface fatigue failure mechanisms both contribute to glenoid implant failure.

Medical devices; reclassification of the shoulder joint metal/polymer/metal nonconstrained or semi-constrained porous-coated uncemented prosthesis. Food and Drug Administration, HHS. Final rule.

The Food and Drug Administration (FDA) is announcing that it is reclassifying the shoulder joint metal/polymer/metal nonconstrained or semi-constrained porous-coated uncemented prosthesis intended to replace a shoulder joint from class III to class II (special controls). The agency is also announcing that it has issued an order in the form of a letter to the Orthopedic Surgical Manufacturers Association (OSMA) reclassifying the device. The special control that will apply is a guidance document entitled "Class II Special Controls Guidance: Shoulder Joint Metal/Polymer/Metal Nonconstrained or Semi-Constrained Porous-Coated Uncemented Prosthesis." The agency is classifying this device into class II because special controls, in addition to general controls, would provide reasonable assurance of the safety and effectiveness of the device, and there is sufficient information to establish special controls.