Surgical Treatment of Marginal Impaction Injuries of The Acetabulum Associated with Posterior Wall Fractures
Authors: Chloros George D. , Ali Ahmed , Kanakaris Nikolaos K. , Giannoudis Peter V. 
Published: March 2022

Background:
Posterior-wall acetabular fractures have been reported to be associated with marginal impaction characteristics in approximately 16% to 38% of cases
1–3
. Early recognition of this special entity of joint impaction is essential for effective preoperative planning, intraoperative execution, and favorable outcomes. The 2-level reconstruction technique is safe and effective in experienced hands.

Description:
The procedure is performed with the patient under general anesthesia, placed under traction in either the prone or lateral position with use of a radiolucent flat-top fracture table and fluoroscopic guidance. The Kocher-Langenbeck approach is utilized. The big posterior wall fracture is identified and reflected in order to visualize the joint surface. Subsequently, traction is applied to facilitate visualization of the marginal impaction area(s). With use of an osteotome, the impacted fragments are disimpacted and elevated. The femoral head is utilized as a template for accurate reduction of the impacted fragments to the acetabular joint surface. The resultant subchondral void is assessed and may be grafted with use of a variety of bone graft materials. The 2-level reconstruction technique may also be considered when the surgeon desires to optimize stability of the impacted fragments and maintain anatomical reduction. The big posterior wall fragment is reduced and fixed with use of the standard posterior-wall reconstruction technique. Finally, irrigation and wound closure in layers is performed.

Alternatives:
Treatment alternatives include either delayed or acute primary total hip arthroplasty in elderly patients >70 years old.

Rationale:
Preoperative identification of the marginal impaction is critical because articular incongruency leads to the development of early posttraumatic osteoarthritis. Achieving joint congruency is especially important in the young population in order to avoid an otherwise unnecessary early total hip arthroplasty.

Expected Outcomes:
Expected radiographic outcomes are excellent or good in 82% of cases, as measured with use of the Matta radiographic score
1–3
. Expected function outcomes are good to excellent in 67.5% of patients, as measured with use of the Modified Merle d’Aubigné system
1–3
. Total hip arthroplasty has been reported as a secondary procedure within 2 years postoperatively in 7.6% of patients
1–3
.

Important Tips:

Joint irrigation is crucial in order to clarify the details of the fragmentation and facilitate removal of debris.Impacted articular cartilage fragments are often rotated and face away from the femoral head.Utilize osteotomes to elevate the impacted area, taking care to mobilize adequate subchondral bone and the accompanying cartilage in case the 2-level reconstruction technique is needed and can be successfully applied.Utilize the femoral head as a template after traction is released to facilitate anatomical reduction.A 1.6-mm Kirschner wire should be available in case it is needed to temporarily stabilize the impacted fragments.Avoid overstuffing the void with bone graft because this may subsequently hinder successful reduction of the posterior wall fragment.

Acronyms and Abbreviations:

CT = computed tomographyAP = anteroposteriorK wire = Kirschner wirePDS = polydioxanone sutureAVN = avascular necrosis