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

Abstract

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.

Introduction

The temporomandibular joint (TMJ) is an atypical diarthrodial synovial joint capable of performing both translation and rotation movements, formed by the mandibular condyle and glenoid fossa of the squamous part of the temporal bone, and separated into upper and lower cavities by the presence of an articular fibrocartilaginous disc. This joint may be the subject of change as a result of numerous different factors, with different causes and intensities, leading to partial or complete loss of functionality.

Although minor disarrangements may be treated by means of more conservative procedures such as discopexy, eminectomy, or arthroplasties, extreme cases can result in ankylosis, severe resorption, or irreparable joint degeneration, making the reestablishment of the functions of the TMJ by these surgical procedures impossible. In these cases, reconstruction by installation of prosthetic TMJ devices has become the best therapeutic choice and provides a safe and viable alternative.

The use of a TMJ prosthesis, when compared to other reconstructive procedures (costochondral grafts, for example), reduces the duration of surgery, reduces morbidity since a donor site is not required, leads to shorter hospitalization times, and provides immediate function, with no need for postoperative intermaxillary fixation (IMF). However, the TMJ prosthesis may also present some disadvantages, including the lack of predictability for a surgical revision, prosthesis failure secondary to either loosening of a screw or fracture of the prosthesis from metal fatigue, the limited fit of stock prostheses, the loss of laterality and protrusion movements due to detachment of the lateral pterygoid muscle, and its high cost.

In recent decades, many prosthetic systems have been developed and marketed but in the long term have given unsatisfactory clinical results and have led to postoperative complications of great importance. Nowadays, just three of these devices are still in use and have been approved by the US Food and Drug Administration (FDA): TMJ Concepts (Ventura CA, USA), TMJ Implants (aka Christensen) (Golden, CO, USA), and Biomet/Lorenz (Jacksonville, FL, USA).

The aim of this study was to evaluate the postoperative clinical results obtained in 300 patients submitted to installation of the Biomet/Lorenz Microfixation TMJ Replacement System over a period of 10 years.

Materials and methods

For this study, data were collected from 300 patients (180 men and 120 women) aged between 20 and 60 years who underwent installation of the Biomet/Lorenz Microfixation TMJ Replacement System between the years 2000 and 2010. Among these patients, 201 underwent unilateral reconstruction and 99 bilateral reconstruction. All patients were considered candidates for joint reconstruction after clinical and imaging examinations (panoramic radiography, computed tomography scans (CT), and, if necessary, magnetic resonance imaging (MRI)) – evaluations that allowed the diagnosis of severe joint changes such as ankylosis, condylar resorption, and articular changes resulting from previous surgical procedures or trauma sequelae. The only inclusion criterion for this study was the joint changes; there was no discrimination with regard to age, gender, race, or dental or occlusal conditions.

Objective (maximum inter-incisal opening; MIO) and subjective (function and speech, diet, and pain) data were collected preoperatively and during postoperative clinical follow-ups performed during a control period of 10 years (mean 3.5, standard deviation (SD) 2.1, range 1–10 years). All patients included in the study were followed for a minimum of 1 year.

Mean values for the results collected during the preoperative period and postoperative period – at 7 days, 1 month, 6 months, 1 year, and annually from the second year after the procedure – were analyzed with the paired t -test (two-sided, α = 5%). Statistical tests were performed with the use of BioEstat software, version 5.0 (BioCistron, Amazon, Brazil)

The Biomet/Lorenz Microfixation TMJ replacement system

This TMJ prosthetic system received approval of its Investigational Device Exception from the FDA in July 1995, and later received Pre-market Approval (PMA). It is a stock prosthetic system composed of three main components: (1) the fossa (temporal) component: made of ultra high molecular weight polyethylene (UHMWPE) this is designed to replace the mandibular fossa and articular eminence of the temporal bone. It is available in three sizes: small, medium, and large. (2) The mandibular component: this is designed to replace the mandibular condyle and is made of cobalt chromium alloy with its undersurface coated with titanium plasma spray for increased bony integration. It is presented in two different designs, standard and narrow, and is also available in three sizes: 45 mm, 50 mm, and 55 mm. (3) The fixation screws: made of 6AL/4V titanium, the screws are self-retaining and self-tapping to facilitate ease of insertion. The fossa component fixating screws are 2.0 mm in diameter and the mandibular component screws are 2.7 mm in diameter.

Surgical procedure

The surgical placement of the prosthetic devices followed a previously established protocol. All patients underwent surgery under general anaesthesia with nasotracheal intubation and complete muscle relaxation. During anaesthetic induction, a prophylactic antibiotic (cefazolin 2 g) and steroid anti-inflammatory (dexamethasone 10 mg) were administered. After infiltration of local anaesthetic with vasoconstrictor in the preauricular region, the TMJ was accessed through a preauricular incision, dissection of the superficial muscle layers, and careful identification and preservation of the facial nerve, until the identification of the joint capsule, which was incised on its lateral portion to expose the condyle and articular fossa. Under continuous irrigation an arthrotomy cut was performed at the level of the sigmoid notch for removal of the compromised condyle. In cases of ankylosis, the ankylotic mass was carefully removed with chisels and round burs. The mandibular fossa was then flattened and the temporal component template of the prosthetic system was adapted and installed after checking the stability and parallelism to the zygomatic arch.

Temporary IMF was then performed to preserve or restore the vertical dimension and occlusion, and the mandibular ramus was accessed through a Risdon incision and communication of the accesses was achieved. The lateral surface of the mandibular ramus was regularized and the mandibular component template was installed and secured to articulate with the previously installed temporal component.

The intermaxillary blockage was then removed, and occlusion, vertical dimension, and mandibular movement were checked. In the case of occlusion or vertical dimension instability, the templates were repositioned and a new occlusal evaluation was performed. In the case of movement restrictions, a second osteotomy, or, if necessary, a coronoidectomy was performed and the templates were reinstalled.

Once no changes were detected, the templates were then replaced for the final prosthetic components and a new mouth opening evaluation was performed. The wounds were carefully rinsed with saline solution and then closed with 4-0 absorbable sutures (polyglactin 910) for the deeper layers and 5-0 nylon sutures for the skin. None of the patients received postoperative IMF. Postoperative medications (antibiotics, anti-inflammatories, and analgesics) were prescribed for all patients.

Postoperative follow-up

The patients were discharged from hospital on average 24 h after surgery and were allowed to function immediately, with freedom to choose any diet.

Intensive physical therapy was initiated 48 h after the procedure. In the first 2 postoperative weeks physical therapy consisted of mandibular opening and closing exercises and stimulation of maximum mouth opening by keeping the mouth open at the wider range limit for a few seconds. From the third postoperative week on, forced mouth opening exercises were introduced with the help of wooden spatulas inserted between the posterior teeth bilaterally, alternating sides, or simultaneously for 2–3 min. The proposed therapy was performed at weekly sessions for a minimum period of 2 months. Patients were encouraged to maintain the exercise routine at home, doing them 3–5 times a day over a period of at least 12 weeks.

For clinical evaluation, each patient was monitored weekly during the first 2 postoperative months. After this period, monthly assessments were performed until the postoperative month 12, and then monitoring was held annually to review progress.

Plain film radiographs were obtained at the first postoperative evaluation, at 6 months, and at the annual visits after the surgery, respecting the radiographic principle of ALARA (‘as low as reasonably achievable’ radiation applied).

Materials and methods

For this study, data were collected from 300 patients (180 men and 120 women) aged between 20 and 60 years who underwent installation of the Biomet/Lorenz Microfixation TMJ Replacement System between the years 2000 and 2010. Among these patients, 201 underwent unilateral reconstruction and 99 bilateral reconstruction. All patients were considered candidates for joint reconstruction after clinical and imaging examinations (panoramic radiography, computed tomography scans (CT), and, if necessary, magnetic resonance imaging (MRI)) – evaluations that allowed the diagnosis of severe joint changes such as ankylosis, condylar resorption, and articular changes resulting from previous surgical procedures or trauma sequelae. The only inclusion criterion for this study was the joint changes; there was no discrimination with regard to age, gender, race, or dental or occlusal conditions.

Objective (maximum inter-incisal opening; MIO) and subjective (function and speech, diet, and pain) data were collected preoperatively and during postoperative clinical follow-ups performed during a control period of 10 years (mean 3.5, standard deviation (SD) 2.1, range 1–10 years). All patients included in the study were followed for a minimum of 1 year.

Mean values for the results collected during the preoperative period and postoperative period – at 7 days, 1 month, 6 months, 1 year, and annually from the second year after the procedure – were analyzed with the paired t -test (two-sided, α = 5%). Statistical tests were performed with the use of BioEstat software, version 5.0 (BioCistron, Amazon, Brazil)

The Biomet/Lorenz Microfixation TMJ replacement system

This TMJ prosthetic system received approval of its Investigational Device Exception from the FDA in July 1995, and later received Pre-market Approval (PMA). It is a stock prosthetic system composed of three main components: (1) the fossa (temporal) component: made of ultra high molecular weight polyethylene (UHMWPE) this is designed to replace the mandibular fossa and articular eminence of the temporal bone. It is available in three sizes: small, medium, and large. (2) The mandibular component: this is designed to replace the mandibular condyle and is made of cobalt chromium alloy with its undersurface coated with titanium plasma spray for increased bony integration. It is presented in two different designs, standard and narrow, and is also available in three sizes: 45 mm, 50 mm, and 55 mm. (3) The fixation screws: made of 6AL/4V titanium, the screws are self-retaining and self-tapping to facilitate ease of insertion. The fossa component fixating screws are 2.0 mm in diameter and the mandibular component screws are 2.7 mm in diameter.

Surgical procedure

The surgical placement of the prosthetic devices followed a previously established protocol. All patients underwent surgery under general anaesthesia with nasotracheal intubation and complete muscle relaxation. During anaesthetic induction, a prophylactic antibiotic (cefazolin 2 g) and steroid anti-inflammatory (dexamethasone 10 mg) were administered. After infiltration of local anaesthetic with vasoconstrictor in the preauricular region, the TMJ was accessed through a preauricular incision, dissection of the superficial muscle layers, and careful identification and preservation of the facial nerve, until the identification of the joint capsule, which was incised on its lateral portion to expose the condyle and articular fossa. Under continuous irrigation an arthrotomy cut was performed at the level of the sigmoid notch for removal of the compromised condyle. In cases of ankylosis, the ankylotic mass was carefully removed with chisels and round burs. The mandibular fossa was then flattened and the temporal component template of the prosthetic system was adapted and installed after checking the stability and parallelism to the zygomatic arch.

Temporary IMF was then performed to preserve or restore the vertical dimension and occlusion, and the mandibular ramus was accessed through a Risdon incision and communication of the accesses was achieved. The lateral surface of the mandibular ramus was regularized and the mandibular component template was installed and secured to articulate with the previously installed temporal component.

The intermaxillary blockage was then removed, and occlusion, vertical dimension, and mandibular movement were checked. In the case of occlusion or vertical dimension instability, the templates were repositioned and a new occlusal evaluation was performed. In the case of movement restrictions, a second osteotomy, or, if necessary, a coronoidectomy was performed and the templates were reinstalled.

Once no changes were detected, the templates were then replaced for the final prosthetic components and a new mouth opening evaluation was performed. The wounds were carefully rinsed with saline solution and then closed with 4-0 absorbable sutures (polyglactin 910) for the deeper layers and 5-0 nylon sutures for the skin. None of the patients received postoperative IMF. Postoperative medications (antibiotics, anti-inflammatories, and analgesics) were prescribed for all patients.

Postoperative follow-up

The patients were discharged from hospital on average 24 h after surgery and were allowed to function immediately, with freedom to choose any diet.

Intensive physical therapy was initiated 48 h after the procedure. In the first 2 postoperative weeks physical therapy consisted of mandibular opening and closing exercises and stimulation of maximum mouth opening by keeping the mouth open at the wider range limit for a few seconds. From the third postoperative week on, forced mouth opening exercises were introduced with the help of wooden spatulas inserted between the posterior teeth bilaterally, alternating sides, or simultaneously for 2–3 min. The proposed therapy was performed at weekly sessions for a minimum period of 2 months. Patients were encouraged to maintain the exercise routine at home, doing them 3–5 times a day over a period of at least 12 weeks.

For clinical evaluation, each patient was monitored weekly during the first 2 postoperative months. After this period, monthly assessments were performed until the postoperative month 12, and then monitoring was held annually to review progress.

Plain film radiographs were obtained at the first postoperative evaluation, at 6 months, and at the annual visits after the surgery, respecting the radiographic principle of ALARA (‘as low as reasonably achievable’ radiation applied).

Results

Numerical MIO results were obtained using a calliper rule, with reference to the upper and lower central incisors on the same side. The subjective data evaluation (function and speech, diet, and pain) was performed using a visual analogue scale (VAS), where for each variable there were six scores (ranging from 0 to 5). Descriptions of the scores for each variable are presented in the separate results sections below ( Fig. 1 ).

Fig. 1
Comparison of the visual analogue scale values during the 10-year period.

Maximum inter-incisal opening (MIO)

The average preoperative MIO was 11.33 mm (SD 4.2). Of the 300 patients evaluated, 168 (56%) had a maximum aperture ranging from 6 to 10 mm and 111 (37%) ranging from 11 to 15 mm. The greatest aperture obtained at this stage was 30 mm, in only one patient. Immediately after surgery, there was a significant increase in MIO (mean 28.1 mm, SD 4.2). At this evaluation, 120 patients presented MIO values equal to 30 mm or greater (maximum 39 mm). At 6 months after surgery, only 13 patients presented an MIO of less than 25 mm; all of these patients reported not having properly performed the postoperative physical therapy exercises, and were again instructed and referred for treatment. After a period of 1 year, only one patient had an MIO of less than 25 mm. The results of MIO increased significantly at all clinical assessments performed during the 3-year period after surgery, reaching an average of 41.8 mm (SD 4.5), with no significant changes from the fourth year of monitoring onwards ( Table 1 ).

Table 1
Maximum inter-incisal opening. This item was evaluated at the following time points: preoperative, immediate postoperative, 7 days, 1 month, 3 months, 6 months, and every year of postoperative follow-up.
Time Patients, n Maximum inter-incisal opening – MIO (mm) P -value (95% CI)
Mean SD Min Max
Preoperative 300 11.33 4.2 6 30 <0.0001 (−17.1, −16.6)
Immediate PO 300 28.1 4.2 21 39 <0.0001 (−0.45, −0.33)
7 days 300 28.6 4.2 21 38 <0.0001 (−1.81, −1.56)
1 month 300 30.3 4.8 21 40 <0.0001 (−7.36, −7.00)
6 months 300 37.4 5.9 23 49 <0.0001 (−1.53, −1.28)
1 year 300 38.9 6 24 49 <0.0001 (−0.58, −0.37)
2 years 279 39.5 5.7 25 49 <0.0001 (−2.2, −1.81)
3 years 212 41.8 4.5 26 49 NS
4 years 193 41.8 4.4 26 49 NS
5 years 166 41.7 4.1 29 49 NS
6 years 114 42.1 3.9 32 49 NS
7 years 77 41.8 3.8 33 48 NS
8 years 49 42 3.8 33 48 NS
9 years 21 42 4.2 32 48 NS
10 years 7 41.4 2.6 38 45
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Jan 24, 2018 | Posted by in Oral and Maxillofacial Surgery | Comments Off on A ten-year experience and follow-up of three hundred patients fitted with the Biomet/Lorenz Microfixation TMJ replacement system
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