CHAPTER 51 Elbow Arthroplasty: Historical Perspective and Emerging Concepts
INTRODUCTION
The first “modern” total elbow arthroplasty using bone cement was performed by Dee in 1972. However, in the late 1940s and early 1950s, documentation of replacement of the elbow by means of hemiarthroplasties as well as custom distal humerus or proximal ulna articular bearing materials exists. All of these efforts suffered from poor fixation and lack of understanding of the joint kinematics. In 1952, Venable48 and in 1965 Barr and Eaton3 designed endoprostheses for the distal humerus, usually for reconstructing traumatic deficiencies (Fig. 51-1). There were also efforts made to create a custom ulnohumeral joint when the elbow was unstable and fusion was the only alternative.11,28,29 These early elbow designs exhibited various articular and fixation concepts (Fig. 51-2). However, without bone cement, these prostheses usually became loose and unstable (see Fig. 51-1).
In the 1970s, the concept of resurfacing emerged. These designs were intended for more limited pathology. Mayo was actively involved with early efforts to design both hemi and articulated devices (Fig. 51-3).23 The so-called “saddle” was a true resurfacing of the olecranon designed at Mayo in the later 1960s, and was successful in some instances38 (Fig. 51-4). Street and Stevens47 are credited with the first use of a convex trochlea and capitellum replacement of the distal humerus (Fig. 51-5). The goal of these implants was a hemiarthroplasty replacement that required less bone resection and, it was hoped, preservation of the collateral ligaments. Materials such as nylon, acrylic, stainless steel, and even vulcanized rubber were used in these early prostheses. Although some were successful in relieving pain, most had limited motion, were often unstable without adequate ligamentous support and loosened over time. A few long-term successes were reported; but in general, joint function was limited and the clinical experience consisted of only a few patients.
The era of total elbow joint prosthetic replacement followed the limited success with these custom-designed and resurfacing hemiarthroplasty. We consider the “modern” era of prosthetic replacement to have begun in the early 1970s with the design of Dee, followed by a number of hinged elbow arthroplasties7,9,19,21,39,46 (Fig. 51-6). This and other prostheses almost uniformly provided pain relief and a reasonable range of elbow motion (20 degrees of extension, to 110 to 120 degrees of flexion).
The important features of the Dee prosthesis is that it was the first implant to use cement fixation. However, the lack of understanding the complex anatomy and biomechanics resulted in a particularly high early failure rate that progressed to virtually 100% failure with time. The disadvantage of rigid fixation and predictable failure was recognized worldwide. Some devices were modified to address the initial design flaws such as the GSB from Zurich (Fig. 51-7). Roland Pritchard was one of the first in this country to recognize the value of a “loose hinge” and a polyethylene bushing (Fig. 51-8). Others sought the desirability of stability and flexibility with a “snap-fit” articulation. The design by Volz also incorporated a radial head to better distribute the forces crossing the joint49 (see Fig. 51-8). Unfortunately these design concepts suffered from deficiencies of technique, soft tissue balance and bushing wear. A less constrained articulation was also attained by a snap fit with some systems (see Fig. 51-8). Finally, Coonrad recognized the problem with a medial/lateral articulation and a collared polyethylene bushing was introduced in 1970 (Fig. 51-9).
Unfortunately, complication rates proved very high from loosening, component fracture, and infection leading to a rate of reoperation of 22% to 30%. Hence, the whole concept was reassessed.
Loosening at the bone-cement interfaces was the predicated price paid for rigid-constraint prostheses.7,10,17 Early recognition of this problem prompted interest in and the development of more prostheses that were not mechanically coupled. These so-called resurfacing or uncoupled designs14,16,25,46 (Fig. 51-10) are best termed unlinked implants and prompted various efforts to restore the anatomic contour. The earliest designs also tried, unsuccessfully, to avoid the use of a stemmed implant. These implants intended to lessen stresses on the bone-cement interface, allowing the soft tissue capsule and ligaments to transmit forces and decrease the risk of mechanical loosening. Over the years, these theoretical advantages have proved to be effective, however, only to the extent that the unlinked device is also less constrained at the articulation. We now know that it is the articular constraint, not the linkage per se, that influences loosening.
Our clinical experience with the more modern designs at the Mayo Clinic began in 1971 with the original Coonrad hinged prosthesis. This was composed of humeral and ulna components separated by a high-density polyethylene bushing (see Fig. 51-9).35 Our experience with this design was flawed by poor stem fixation (Fig. 51-11). With a more sophisticated understanding of biomechanics and after studying our own and the clinical experience of others, a three-piece, semiconstrained, flanged device was designed in 1978 (Fig. 51-12). Morrey inserted two of these devices, and the second one dislocated. The design was abandoned, but the value of the flange concept was believed to be sound and it was incorporated into the Coonrad implant.
