A breach of the medial acetabular wall is a phenomenon seen frequently due to over-reaming during total hip arthroplasty (THA). The consequences of this issue are not fully understood particularly in cementless THA. A retrospective study was performed to answer whether: (1) immediate postoperative full-weight bearing in the presence of a medial acetabular wall breach after THA results in more short-term revisions of the acetabular component, (2) increases the risk for migration of the acetabular component?

Immediate full-weight bearing in the presence of a medial breach is not associated with an increased likelihood for acetabular-related revision surgery or migration of the cup.

In this retrospective cohort study, consecutive patients (n=95; mean age 68±13 years; 67 female) who underwent THA with an uncemented acetabular component were identified and a retrospective chart review was performed (follow-up 23±17 months, range 6 to 79 months). The presence of a postoperative radiographic medial acetabular breach was documented and the need for revision surgery and the rate of acetabular component migration were assessed during follow-up.

Some extent of radiographic medial acetabular wall breach was seen in 26/95 patients (27%). With regard to the primary outcome, 2/95 patients (2%) required revision surgery during follow up. All revision surgeries occurred in the group without a medial breach (p=0.280) for causes related to the femoral or the head components. Persistent pain was present in 1/26 patients (3.8%) in the medial breach group and 8/69 patients in the control group (11.6%; p=0.436). In the radiographic follow-up, (n=81), there was no significant difference between the control group and the medial breach group with regard to cup migration (Δ ilio-ischial overlap (distance between the ilio-ischial line and a parallel line tangential to the acetabular cup on AP views): −0.5±0.9mm (range, −2.9 to 0.8) vs. −0.3±1.7mm (range, −1.9 to 2.2), Δ overlap tangent (defined as the distance between the two crossings of ilio-ischial line and the acetabular component on AP views): −2.2±6.1mm (range, −21.4 to 0.0) vs. 0.4±6.9mm (range, −6.2 to 17.6). Similarly, according to variation in the ilio-ischial overlap distance between postoperative and follow-up on pelvic AP views, 0/56 hips (0%) had cup migration≥5mm in the control group versus 1/25 (4%) in the medial breach cohort (p=0.3).

In this retrospective observation of patients with immediate postoperative full-weight bearing after THA, a radiographic breach of the medial acetabular wall was not associated with an increased risk for short-term revision surgery or radiographic migration at follow-up. According to the findings of this study and in the light of previous biomechanical studies, there is no clear evidence for postoperative partial-weight bearing in case of a medial breach as far as the surgeon feels that the acetabular component is stable.

IV, Retrospective cohort study.