Kerboull acetabular ring device with allograft for chronic pelvic discontinuity

Background

The demand for total hip and knee replacement is increasing at a frenetic rate. Data from prior studies ^, and projection investigations demonstrate that the number of revision total hip arthroplasty (THA) will rise 137% over the next 25 years in the United States, and similar trends have been observed in the United Kingdom and Australia. ^, Among revision THA, Bozic et al. have shown that acetabular component revision was the third most common procedure (12.7%) following femoral component revision (13.2%) and all-component revision (41.1%). Major advances have been made in the engineering and manufacturing of alternative bearing surfaces. Among these, ceramics and first- and second-generation highly crossed-linked polyethylene (XLPE) are now available for primary THAs, dramatically mitigating wear and osteolysis. Nevertheless, although significantly decreased, osteolysis is still responsible for up to 11% of all revision THAs. ^,

DeLee and Charnley mapped the retroacetabular region into three different zones to identify areas of osteolysis. This classification is still in use nowadays. Chiang et al. have shown that the pattern of osteolysis differs between modes of fixation of the acetabular component. For cemented cups, osteolysis predominantly occurs in DeLee zones III and I, whereas it is mostly observed in DeLee zones II and III for cementless cups. Resultant osteolysis and bone loss patterns can be categorized through different classifications. (Bone loss classifications are detailed in Chapter 2 ).

Reconstruction techniques of the damaged acetabulum are guided by the severity of the bone defects. Studies have demonstrated that when contact between viable bleeding host bone and a porous-coated acetabular implant is greater than 50%, assuming adequate initial mechanical stability, then reliable osseointegration can be expected. In contrast, when 50% of contact cannot be obtained between host bone and the acetabular component, studies have shown that an acetabular reinforcement ring is indicated.

In this chapter, we will discuss the use of the Kerboull Acetabular Reconstruction Device (KARD) with allograft in the setting of chronic pelvic discontinuity. Premise: This technique is based on the combination of an acetabular reinforcement cage (Kerboull device) with bone allograft and a cemented acetabular component to manage massive acetabular bone defects (including pelvic discontinuity) during revision THA.

The Kerboull acetabular reinforcement device and its evolution

In the early 1970s, at the authors’ institution, chronic pelvic discontinuities associated with acetabular bone loss were encountered in some cases of failed metal on metal (MoM) THAs. In 1974, Marcel Kerboull designed a special acetabular ring, hemispheric cross-shaped, with four arms, an inferior hook, and a superior plate to fix the fracture and implant a new cup in one stage. Initially intended for this indication, this device was subsequently used as a guide and reinforcement with bulky frozen femoral head allografts in almost all acetabular reconstruction procedures. This device can also be used in primary THAs in which there is weak bone or remodeled acetabular anatomy seen with prior acetabular fractures or pelvic osteotomies. A series of reconstructions performed with the original KARD have been reported from France, whereas modifications to its design and material have been made in Japan by Chiaki Tanaka, with favorable results. It should be emphasized that most of the early failures were related to inadequate surgical technique.

Mechanical principles

The KARD design is a semi-rigid and open component which prevents graft overloading during the initial osseointegration process that begins with osteoclastic resorption. Moreover, because of its specific design, when adequately positioned, one can expect to accurately reconstruct the acetabular bone defect and position the acetabular cup. To reach this goal, it is paramount to choose the adequate size of the KARD and not alter its shape, which modifies its mechanical properties and jeopardizes long-term clinical outcomes.