Unlinked Prosthesis Research Articles

Revision of Unstable Capitellocondylar (Unlinked) Total Elbow Replacement

Instability is a recognized complication associated with unlinked total elbow implants. The best form of treatment of this problem is uncertain as very little has been written about it. Twelve patients underwent operative treatment of instability at the site of a capitellocondylar unlinked total elbow replacement, and the results were reviewed retrospectively. The study group included ten women and two men with an average age of fifty-eight years. Ten patients had rheumatoid arthritis. Three elbows underwent conversion to a semi-constrained hinged prosthesis. In the other nine elbows, an attempt was made to continue with an unlinked prosthesis: three had reconstruction of one or both collateral ligaments, four had component revision, and two had both ligament reconstruction and component revision. After an average duration of follow-up of six years (range, two to fifteen years) only three patients had retained a functioning unlinked prosthesis. Of the remaining nine patients, three had had a conversion to a semi-constrained arthroplasty at the time of the index procedure, four had had a conversion to a semi-constrained prosthesis at the time of a salvage procedure, one had had a resection arthroplasty, and one had a painfully dislocated elbow and had declined revision. Thus, seven elbows eventually underwent conversion to a semi-constrained prosthesis; these conversion procedures were technically difficult, with perforation of the humerus occurring in six patients and perforation of the ulna occurring in four. After all procedures, the average elbow flexion was 132 degrees and the average flexion contracture was 25 degrees. According to the Mayo Elbow Performance Index, there were four excellent results, three good results, three fair results, and one poor result. Revision of an unlinked total elbow prosthesis to a linked total elbow prosthesis is difficult, but it restores elbow function. Although the present series documents the unpredictability of attempts to salvage an unstable unlinked prosthesis, it seems reasonable to attempt at least one soft-tissue procedure before converting to a linked prosthesis.

REVISION OF UNSTABLE CAPITELLOCONDYLAR (UNLINKED) TOTAL ELBOW REPLACEMENT

Background: Instability is a recognized complication associated with unlinked total elbow implants. The best form of treatment of this problem is uncertain as very little has been written about it. Methods: Twelve patients underwent operative treatment of instability at the site of a capitellocondylar unlinked total elbow replacement, and the results were reviewed retrospectively. The study group included ten women and two men with an average age of fifty-eight years. Ten patients had rheumatoid arthritis. Three elbows underwent conversion to a semiconstrained hinged prosthesis. In the other nine elbows, an attempt was made to continue with an unlinked prosthesis: three had reconstruction of one or both collateral ligaments, four had component revision, and two had both ligament reconstruction and component revision. Results: After an average duration of follow-up of six years (range, two to fifteen years) only three patients had retained a functioning unlinked prosthesis. Of the remaining nine patients, three had had a conversion to a semiconstrained arthroplasty at the time of the index procedure, four had had a conversion to a semiconstrained prosthesis at the time of a salvage procedure, one had had a resection arthroplasty, and one had a painfully dislocated elbow and had declined revision. Thus, seven elbows eventually underwent conversion to a semiconstrained prosthesis; these conversion procedures were technically difficult, with perforation of the humerus occurring in six patients and perforation of the ulna occurring in four. After all procedures, the average elbow flexion was 132° and the average flexion contracture was 25°. According to the Mayo Elbow Performance Index, there were four excellent results, three good results, three fair results, and one poor result. Conclusions: Revision of an unlinked total elbow prosthesis to a linked total elbow prosthesis is difficult, but it restores elbow function. Although the present series documents the unpredictability of attempts to salvage an unstable unlinked prosthesis, it seems reasonable to attempt at least one soft-tissue procedure before converting to a linked prosthesis. Level of Evidence: Therapeutic Level IV. See Instructions to Authors for a complete description of levels of evidence.

Importance of a radial head component in Sorbie unlinked total elbow arthroplasty.

The effects of a radial head component on total elbow arthroplasty kinematics and stability were evaluated using an anatomic design unlinked total elbow prosthesis. An electromagnetic tracking device recorded motion and varus and valgus displacements under various conditions in 10 cadaveric elbows. The motion patterns of the intact elbows and the Sorbie-Questor total elbow prostheses with a radial head component were similar, as both tended to have a valgus position in extension, varus at midflexion, and more valgus toward full flexion. Under conditions of simulated muscle loading, the maximum valgus and varus laxity of the elbow prosthesis was, on average, 8.6 degrees +/- 4.0 degrees greater than normal. Without the radial head component, however, significant kinematic disturbances and instabilities were seen. The varus and valgus displacements were 13.3 degrees +/- 5.5 degrees greater than the intact elbows. One total elbow arthroplasty without a radial head dislocated during testing. Increasing the muscle loading across the elbow significantly enhanced dynamic stability of the total elbow arthroplasties, especially in the extension half of elbow motion where instability is greatest. However, this dynamic enhancement of stability was seen only in those elbows in which the radial head component had been implanted. The radial head component is an important stabilizer, particularly in extension for this prosthesis, and possibly for other unlinked total elbow prostheses. Although instability of unlinked prostheses depends on the prosthetic design, the use of a radial head replacement may be an important factor in preventing such instability. Perhaps even more importantly, a radial head component balances the load distribution across the articulation, which could decrease stress on the ulnohumeral articulation and therefore possibly reduce polyethylene wear, osteolysis, and loosening.

Kudo total elbow arthroplasty in patients with rheumatoid arthritis: a long-term follow-up study.

Improvements in the design of total elbow prostheses over the last two decades have led to better and more consistent results. The type-3 Kudo total elbow prosthesis was developed in 1980. The long-term results of use of this implant have not been reported. Because it is an unlinked prosthesis, it is not known whether preservation of the anterior oblique component of the ulnar collateral ligament at the time of implantation is important. A type-3 Kudo total elbow arthroplasty with cement was performed in forty-seven patients (fifty elbows) with rheumatoid arthritis. Revision rates, clinical symptoms, postoperative complications, and radiographic changes were assessed eleven to sixteen years (mean, thirteen years) postoperatively. The overall survival rate of the prosthesis was 90% at sixteen years. The mean Mayo elbow performance scores were all poor (mean overall score, 43 points) initially. The overall score was substantially improved at both the intermediate follow-up examination (four to six years after the operation) and the late follow-up examination (eleven to sixteen years after the operation), to 81 and 77 points, respectively. The overall rate of radiolucency about the humeral component was 45% at the intermediate follow-up examination and 100% at the long-term follow-up examination. The rate of radiolucency about the ulnar component at the intermediate and late follow-up examinations was 4.3% and 8.9%, respectively. No great differences in results were found with preservation of the anterior oblique component of the ulnar collateral ligament. This long-term follow-up study showed acceptable results of the type-3 Kudo total elbow arthroplasty in patients with rheumatoid arthritis. Preservation of the ulnar collateral ligament does not seem to be necessary when performing this procedure.

Total Elbow Replacement in the Treatment of Rheumatoid Disease

Improvements in total elbow arthroplasty during the last 20 years have resulted in clinical outcomes which now are comparable with the results of hip arthroplasty. The main types of prostheses used are unlinked prostheses or semiconstrained hinged prostheses. The unlinked prostheses require the preservation of bone stock and the ability to reconstruct the collateral ligaments to achieve stability. Semiconstrained, hinged prostheses have inherent stability but humeral loosening was initially a problem. Stress transfer through the humeral stem can be reduced by using a prostheses with anterior flanges (Coonrad-Morrey or GSB3). Survivorship analyses beyond 10 years now are becoming available for these prostheses. There has been no universal agreement as to which outcome measure should be used for total elbow replacements. Future developments will include an evolution of principles as understanding of elbow biomechanics progresses. Operative technique is likely to be modified by the development of alignment aids and jigs.

Non-constrained elbow arthroplasty for mutilans deformity in rheumatoid arthritis

Six highly unstable elbows with severe bone loss due to rheumatoid arthritis were replaced by a non-constrained, unlinked prosthesis. Bone defects were filled with autogenous bone grafts. The mean follow-up was 4.5 years (2 to 8). The clinical results were excellent in four elbows and good in two, with good varus-valgus stability in all. Radiological follow-up showed no appreciable signs of loosening, and the bone grafts had retained most of their original size, with minimal resorption. There were no major complications such as dislocation, skin necrosis, infection or ulnar neuropathy. The study has shown that the so-called mutilans elbow can be successfully replaced using a properly selected type of non-constrained, unlinked prosthesis with bone grafting of the major defects.

Non-constrained elbow arthroplasty for mutilans deformity in rheumatoid arthritis: a report of six cases.

Six highly unstable elbows with severe bone loss due to rheumatoid arthritis were replaced by a non-constrained, unlinked prosthesis. Bone defects were filled with autogenous bone grafts. The mean follow-up was 4.5 years (2 to 8). The clinical results were excellent in four elbows and good in two, with good varus-valgus stability in all. Radiological follow-up showed no appreciable signs of loosening, and the bone grafts had retained most of their original size, with minimal resorption. There were no major complications such as dislocation, skin necrosis, infection or ulnar neuropathy. The study has shown that the so-called mutilans elbow can be successfully replaced using a properly selected type of non-constrained, unlinked prosthesis with bone grafting of the major defects.

Excision of the Cruciate Ligaments in Total Knee Replacement

The cruciate ligaments (and the intercondylar eminence of the tibia) should be removed when the knee is replaced. A mechanically unlinked prosthesis can be designed which will then be capable of restoring "cruciate" stability, i.e., anteroposterior stability of the tibia in the flexed knee. A knee replaced with such a prosthesis will only be stable if the prosthesis is inserted using the correct instruments and technique. Stability depends as much on precise surgical technique as it does on prosthetic design.