To the best of our knowledge, there have been no previous reports on results of TEA conducted at a nationwide level. The mean annual incidence of TEA was 1.3 per 100,000. We found no differences in survival between different TEA designs or concepts, based on the data recorded in the Finnish Arthroplasty Register. The most significant finding in our study was the better TEA survival when performed in a hospital that specialized in the treatment of rheumatoid arthritis.
We are aware that the current register-based study had certain limitations. For example, we were not able to report any subjective outcome measurements, e.g. Mayo Elbow Performance Score or disease-specific quality of life measurements. Moreover, it is not possible to conduct radiographic analyses in the large number of register-based patients. Furthermore, when rheumatoid patients are involved, a register-based study may have the pitfall that some of the patients diagnosed as having RA may actually be affected by juvenile arthritis or other subtypes of chronic arthritis. Little is known about TEA in different subtypes of chronic arthritis (Connor et al 1998
The primary indication for TEA is a painful arthritic elbow with Larsen grade-IV or grade-V (Larsen et al. 1977
) rheumatic destruction (Scott et al. 1986
, Hämäläinen et al. 1991
, Little et al. 2005a
). There are only limited published data to guide a surgeon in implant selection. A recent systematic review of the English-language literature (Little et al. 2005a
) found that a high proportion of the published studies on TEA had originated from the establishments of the designers of the implants. In addition, no recognized form of survival analysis such as the Kaplan-Meier technique had usually been used in these studies. In their attempt to re-calculate the revision rates for different TEA designs in patients with RA, Little et al. found an overall revision rate of 13% at 5 years. Our register-based study has revealed a similar rate of prosthesis survival, with 88–89% of patients revision-free at 7 years.
Traditionally, the TEA designs have been divided into 3 categories: fully constrained rigid-hinge design, semi-constrained hinge design, and unconstrained unlinked design. Fully constrained designs have a lack of flexibility in the coronal plane and in rotation, resulting in high shear stresses and early loosening rates, and these model are no longer in use (Garrett et al. 1977
, Amis et al. 1981
). Unconstrained models rely on sufficient bone stock and an intact soft tissue sleeve, whereas the semi-constrained designs can be used in an elbow that is unstable because of bone or soft tissue deficiency (Wright et al. 2000
). There are, however, reports of favorable results after TEA with the use of the unconstrained Souter-Strathclyde implant for the severest forms of rheumatic destruction and substantial bone loss (Ikävalko et al. 2004
). On the other hand, Kamineni and colleagues (2005)
found large variation in intrinsic constraint of unlinked TEA designs. Thus, it may not be practical to consider all unlinked prostheses as a group. In their review article, Little and colleagues (2005a)
found no differences in survival between different prostheses or concepts. In the studies comparing contemporary TEA designs, it has not been possible to demonstrate the superiority of one model or concept over another (Connor et al. 1998
, Wright et al. 2000
, Little et al. 2005b
In the present study, we pooled the results of the Kudo prosthesis and its latest version (i.B.P.), and we also pooled the data for the NESimplavit and its former brand, the Norway prosthesis. In spite of this, we could not find statistically significant differences between survival rates of the different designs. In their comparative study of 3 implants using any revision as the endpoint, Little and coworkers (2005b)
found the 5-year survival rates of the Souter-Strathclyde, Kudo, and Coonrad-Morrey implants to be 85%, 93%, and 90%. The differences were not statistically significant, however. Our survival rates () are in line with their findings.
Several studies have found an association between the hospital volume and adverse events in the context of total hip arthroplasty (THA), but no such studies on TEA have been published. Both surgeon volume and hospital volume have been suggested to be the best indicators of orthopedic adverse events in patients undergoing THA (Solomon et al. 2002
). In a systematic literature review, an association was found between higher hospital volumes and lower rates of mortality and hip dislocation (Shervin et al. 2007
). Inferior survival rates of the TEAs performed in the unpecialized hospitals demonstrate the importance of proper indications, surgical technique, and postoperative follow-up, and endorse the centralization of these operations at specialized units.
The inferior survival rates in the Souter-Strathclyde TEAs implanted in the early years of the Finnish Arthroplasty Register have improved over the years. Possible reasons for this include better surgical technique with triceps-sparing approaches, better cementing technique and equipment, and a postoperative regime that allows the triceps to heal. Also, it is possible that the elbows that underwent earlier operations may have undergone more severe destruction from RA, and were thus less optimal for implant arthroplasty.
According to our results, it appears that success of reconstruction of a non-weight bearing joint such as the elbow by means of TEA is not as affected by implant choice to the same extent as hip (Eskelinen et al. 2005
) and knee (Robertsson et al. 2001
) arthroplasty. The explanation for this may be that both the contemporary semi-constrained and unconstrained TEA designs perform in a more or less unconstrained manner when properly inserted (Hargreaves and Emery 1999