Commentary on
"Cementless Acetabular Reconstruction After Acetabular Fracture"
By Carlo Bellabarba, MD, et al.

Commentary by Dennis K. Collis, MD*,
Orthopedic Healthcare Northwest, Eugene, OR

This article will be helpful to the orthopaedic surgeon planning total hip arthroplasty in patients with painful degenerative arthritis secondary to acetabular fracture. Bellabarba et al. conclude that cementless acetabular components work as well in this patient population as they do in patients with nontraumatic arthritis. They appropriately point out that there has been very little in the literature about the use of cementless prostheses in the treatment of painful arthritis following traumatic injury to the acetabulum¹. The authors also reported that the results of uncemented acetabular components were better than those previously reported² for cemented acetabular components in the same clinical setting.

Personally, I found the most useful part of this article to be the authors' description of the surgical techniques used in these procedures. In the surgical details included in the Materials and Methods section, they indicated that hardware was removed only as needed to allow proper press-fitting of the acetabular component. The authors furthermore stated that, when bone-graft was required, morselized cancellous bone-graft was sufficient and that structural bone-grafting was not necessary. Only one of these thirty total hip replacements required revision. It involved an attempt to stabilize a pelvic nonunion with the prosthesis itself. The authors recommend that pelvic nonunion be stabilized with appropriate internal fixation prior to implanting the acetabular component. Bellabarba et al. attempt to compare the results of cementless acetabular reconstruction in patients who have had previous open reduction and internal fixation of the original acetabular injury with those of patients who had closed treatment of the acetabular injury. Unfortunately, only fifteen hips in each treatment group does not permit a sufficiently high power to their statistical analysis. They were able to report, as one might expect, that the patients who did not have previous operative treatment of their acetabular fractures had a much shorter operative time (by an average of 45 minutes) and much less intraoperative blood loss (an average difference of 503 mL). Furthermore, they indicated that more patients in the open-reduction group required elevated acetabular liners to obtain stability. All of these findings would be expected, but it is important to be reminded that previous hip surgery necessitates a more complicated total hip replacement. The authors appropriately do not use these differences as any indication for whether to utilize open reduction and internal fixation for the primary treatment of acetabular fracture. Since these thirty consecutive hips are collected from an unknown denominator of acetabular fractures, it would be beyond the scope of this study to draw such conclusions.

In this study, it is difficult to discern how severe the original injuries were since the authors were not the original treating surgeons and probably did not even have the original radiographs. In Table 1, all thirty fractures were described as high-energy injuries, but I suspect that some resulted from high-speed auto accidents and others, from falls. Therefore, the extent of trauma to the acetabulum was probably quite different in the open-reduction group and the closed-treatment group.

The most disappointing part of this article is the authors' attempt to compare this series of thirty hip replacements with another study of total hip replacements conducted previously at the same institution³. Although Bellabarba et al. attempted to illustrate that the two arthritis groups (posttraumatic and nontraumatic) were similar (Table I), it should be pointed out that the previously reported study involved a consecutive series of cementless total hip arthroplasties performed between 1984 and 1985, when uncemented components were first being used; therefore, those procedures were all performed in the early phase of the learning curve for placement of uncemented components, sixteen years ago or more. In contrast, the group of thirty patients with posttraumatic osteoarthritis in this report were treated between 1984 and 1995, and, thus, many had the benefit of ten years of learning experience. When comparing these two studies, the conclusions become less valid. Even though the two groups are similar with regard to gender and age, the duration of follow-up is considerably longer (104 months) in the nontraumatic group³ compared with that in the posttraumatic group (63 months) in the present study. Therefore, the fact that a similar failure rate has been noted in both groups is less meaningful. One indication that the failure rate of the thirty hips reported by Bellabarba et al. might indeed increase with a longer duration of follow-up is illustrated by the 67% prevalence of radiolucent lines in the posttraumatic group compared with 41% in the nontraumatic group. Therefore, I think that although the authors have demonstrated that success with use of a cementless acetabular component can be obtained in patients with posttraumatic arthritis secondary to acetabular injury, they do not establish that the results are comparable with those of a standard primary hip replacement in patients with nontraumatic degenerative arthritis.

In summary, I think that this article is valuable because it describes techniques and methods for surgical treatment of posttraumatic osteoarthritis in hips that have sustained acetabular injuries and it illustrates the complexities inherent in these operations. Necessarily, Bellabarba et al. have not provided firm indications for which patients with an acute acetabular fracture should be treated operatively. However, restoration of the osseous anatomy would appear to be an appropriate goal of treatment. This article gives the clear message that uncemented acetabular components are more efficacious than cemented components when hip replacement is necessary in patients with posttraumatic osteoarthritis after acetabular injury.

*The author did not receive grants or outside funding in support of his research or preparation of this manuscript. He did not receive payments or other benefits or a commitment or agreement to provide such benefits from a commercial entity. No commercial entity paid or directed, or agreed to pay or direct, any benefits to any research fund, foundation, educational institution, or other charitable or nonprofit organization with which the author is affiliated or associated.

References

1. Pritchett JW, Bortel DT. Total hip replacement after central fracture dislocation of the acetabulum. Orthop Rev. 1991;20:607-10.
2. Romness DW, Lewallen DG. Total hip arthroplasty after fracture of the acetabulum. Long-term results. J Bone Joint Surg Br. 1990;72:761-4.
3. Tompkins GS, Jacobs JJ, Kull LR, Rosenberg AG, Galante JO. Primary total hip arthroplasty with a porous-coated acetabular component. Seven-to-ten-year results. J Bone Joint Surg Am. 1997;79:169-76.