Osseointegrated wrist-joint prostheses: A 15-year follow-up with focus on bony fixation

Five patients with rheumatoid arthritis or osteoarthrosis of the wrist joint were followed up for 15 (14–17) years after wrist-joint arthroplasty with semiconstrained artificial joint mechanisms that had been anchored to bone using the osseointegration principle. They were fixed by one titanium screw introduced into the radius, and two or more titanium screws introduced distally into the metacarpal bones. In four cases a screw was also introduced into the ulna thereby constituting one component in a distal radio-ulnar (DRU) joint mechanism. The titanium screw introduced into the radius and the distal metacarpal screws osseointegrated in all cases. In three cases the mechanism of the wrist joint or parts of it were replaced with new components that could be attached to the screws that were already osseointegrated. We conclude that wrist joint prostheses can be anchored to the surrounding bone using osseointegration and that they remain fixed for at least 15 years. The principle allows replacement of the joint mechanism, if needed, with maintenance of the osseointegrated anchoring elements.     

Zygoma fixture in the management of advanced atrophy of the maxilla: technique and long-term results.

Despite refinements in surgical technique, including bone grafting and sophisticated prosthetic reconstructions, there are limitations to what can be achieved with bone-anchored fixed prostheses in patients with advanced atrophy of the maxillae. A new approach was suggested by a long-term study on onlay bone grafting and simultaneous placement of a fixture based on a new design: the zygoma fixture, and the aim of this study was to assess its potential. Twenty-eight consecutive patients with severely resorbed edentulous maxillae were included, 13 of whom had previously had multiple fixture surgery in the jawbone that had failed. A total of 52 zygoma fixtures and 106 conventional fixtures were installed. Bone grafting was deemed necessary in 17 patients. All patients have been followed for at least five years, and nine for up to 10 years. All patients were followed up with clinical and radiographic examinations, and in some cases rhinoscopy and sinoscopy as well. Three zygoma fixtures failed; two at the time of connection of the abutment and the third after six years. Of the conventional fixtures placed at the time of the zygoma fixture, 29 (27%) were lost. The overall prosthetic rehabilitation rate was 96% after at least five years of function. There were no signs of inflammatory reaction in the surrounding antral mucosa. Four patients with recurrent sinusitis recovered after inferior meatal antrostomy. To conclude, the zygoma fixture seems to be a valuable addition to our repertoire in the management of the compromised maxilla.     

Osseointegration in maxillofacial prosthetics. Part I: Intraoral applications

Osseointegrated implants can provide anchorage and promote prosthesis stability in a variety of oral defect situations. The application of proven TIP fixture principles and techniques to these patients has allowed high level of function to be attained with great promise for longevity.     

Biomechanical characterization of osseointegration: An experimental in vivo investigation in the beagle dog

This study reports the results of torsion tests, pull-out tests, and lateral Ioading tests on osseointegrated commercially pure titanium fixtures. The tests were performed in vivo on six beagie dogs. Three fixtures, each with a diameter of 3.7mm, were installed bilaterally in the tibia of each animal. The mean maximal pull-out load was 1.55 kN (n = 4) the mean maximal lateral transverse load was 0.21 kN (n = 2), the mean maximal lateral axial load was (0.18 kN (n = 2)) the mean breakpoint torque was 0.31 Nm (n = 3), and the mean maximal torque was 0.43 Nm (n = 3). The torsion test revealed an almost immediate plastic deformation of the interface between the implant and bone: this indicates that although the contact between the bone and the implant is close, there is no strong bond, at least not in shear. The major transfer of load from the implant to the surrounding bone tissue must therefore depend on the design of the implant. A histological evaluation with measurements of the amount of bone in contact with the fixtures was performed. By the use of the histological and mechanical data, it is possible to estimate shear stresses in bone tissue (pull-out test) and in the interface (torque test), The mean maximal shear stress in bone tissue in the pull-out tests was 100 MPa (n = 4); the mean shear stress in the interface was 4.3 MPa (n = 3) in the torsion tests at the breakpoint torque and was 6.0 MPa (n = 3) at the maximal torque. It was also possible to estimate the shear modulus of elasticity in the pull-out and torque tests. The mean shear modulus in pull-out was 119 MPa (n = 4), and the mean apparent shear modulus in torsion was 9 kPa (n = 3) for an assumed interface thickness of 100 nm and was 86 kPa (n = 3) for an assumed interface thickness of 1.000 nm.     

A clinical evaluation of fixed-bridge restorations supported by the combination of teeth and osseointegrated titanium implants

Abstract. The present paper reports on the result of the use of osseointegrated titanium fixtures and teeth as combined abutments for fixed-bridge restorations in 10 partially dentate patients. In these patients, the remaining teeth were too few or too unfavourably distributed in the jaws to serve as sole abutments for fixed bridgework. Titanium fixtures ad modum Brånemark were therefore implanted in suitable positions and used as abutments in combination with the remaining teeth. Evaluations at periods of 6 to 30 months postoperatively revealed good clinical results. Some tissue reactions, however, were also observed, indicating the presence of certain clinically significant differences in the functional behaviour of tooth abutments and titanium fixture abutments. These reactions and differences are discussed.     

Osseointegration of titanium implants

Forty-eight screws, six double cylindrical implants and six T-plates were inserted into the tibia or femur of 6 dogs. Two titanium screws were inserted into the proximal tibia of 5 patients to anchor a titanium mould. The implants were removed en bloc with adjacent bone tissue after 3 to 14 months. They were sectioned using a technique that allowed analysis of the intact tissue-to-metal specimens. Osseointegration, defined as a direct bone-to-implant contact without interposed soft tissue, was confirmed in all screw-shaped implants while the cylindres had only partial bone contact as did the T-plates. We conclude that osseointegrated implants may be applicable in joint reconstruction for arthrosis or rheumatoid arthritis.     

Clinical evaluation of the zygoma implant: 3-year follow-up at 16 clinics.

PURPOSE: The purpose of this clinical investigation was to evaluate the treatment outcome with zygoma implants with regard to implant survival, patient satisfaction, and function of prosthesis replacement after 3 years. PATIENTS AND METHODS: The treatment outcome of 76 patients treated with 145 zygoma fixtures at 16 centers was evaluated with regard to implant survival. Status of peri-implant mucosa and amount of plaque were registered annually. Patients' and dentists' evaluations of the functional and esthetic outcome of the treatment were assessed at delivery of prosthesis and thereafter at each follow-up visit. RESULTS: Sixty of 76 patients were followed for 3 years after prosthetic delivery. Five of 145 placed zygoma implants failed during the course of the study resulting in an overall implant survival rate of 96.3%. At the 3-year follow-up, 75% of the implants sites were registered with normal peri-implant mucosa and 68% with no visible plaque. The patients were fully satisfied with the esthetic and functional outcome of the treatment in 86% and 71%, respectively, at the 3-year follow-up visit. All reported data from dentists scored from acceptable to excellent. CONCLUSION: The multicenter study showed a high predictability of the zygoma implant-supported rehabilitation.     

An experimental method for in vivo studies of pulmonary platelet sequestration

It has been reorted in earlier in vitro studies that soft tissue trauma and endotoxin-induced shock causes pulmonary platelet trapping (PPT). This paper describes a noninvasive in vivo technique for dynamic studies of PPT in rabbits. Autologous platelets were labeled with¹¹¹In and reinfused into the animals. The following day, the rabbits were anesthetized and placed in a supine position under a scintillation camera. Continuous measurement of the activity distribution in the animal was performed for 35 min. The first 5 min represented a preshock measurement, whereafter endotoxinE. coli was injected IV. The following 2–3 min showed a sudden increase of radioactivity in the lungs indicating PPT, and thereafter a slow decrease to almost the preshock level. A simultaneous decrease in the number of platelets and the radioactivity in peripheral blood also indicated the induction of PPT. This study clearly shows that PPT can be detected in vivo with an easy, noninvasive scintillation camera method.This study was supported by grants from John and Augusta Persson's Foundation for Scientific Research, Lund, Sweden