JOT - 2026-09-23 - Journal Article
Pre-Reduction Position of Posterior Wall Fragment is Associated with Intra-Articular Displacement.
Park CC, Barth KA, Falgons CG, Galloway J, Gardner S, Lee Chip Routt M, Kellam PJ, Eastman JG, Warner SJ
Topics
Key Takeaway
When a posterior wall fragment is positioned medial to the femoral head before closed reduction, 100% of fragments that subsequently displaced intra-articularly shared this position, and medial position was associated with non-concentric reduction in 74.2% of cases (OR 6.5).
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Summary
This study examined the rate and predictors of posterior wall fragment intra-articular displacement following closed reduction of posterior acetabular fracture-dislocations in 44 patients with pre-reduction CT demonstrating fragment interposition. Post-reduction CT confirmed intra-articular displacement in 21 of 44 patients (47.7%). Medial pre-reduction fragment position (100% vs. 26.1%, p<0.001), inferior position (OR 37.5, p<0.001), and smaller fragment length (2.6 vs. 3.6 cm, p=0.003) each independently associated with intra-articular translation; medial position also predicted non-concentric reduction (OR 6.5, p=0.015).
Key Limitation
The extremely wide confidence interval for inferior fragment position (OR 37.5, 95% CI 4.2–333.1) reflects the small sample size and renders the magnitude of that association unreliable for clinical decision thresholds.
Original Abstract
OBJECTIVES
To characterize the rate and risk factors for a posterior wall fragment becoming intra-articular following closed reduction in posterior acetabular fracture-dislocations when the fragment was positioned between the femoral head and acetabulum prior to reduction.
METHODS
Design: Retrospective case series.
SETTING
Regional Level 1 trauma center.
PATIENT SELECTION CRITERIA
Patients with posterior wall, posterior column-posterior wall, or transverse-posterior wall acetabular fracture-dislocations and posterior hip dislocation between January 2019 and December 2023 were reviewed. Inclusion required pre- and post-reduction CT imaging demonstrating a posterior wall fragment between the femoral head and acetabulum.
OUTCOME MEASURES AND COMPARISONS
Pre- and post-reduction CT scans were reviewed to define fragment position relative to the femoral head and determine whether fragments were intra- or extra-articular after reduction.
RESULTS
Of 44 patients with a posterior wall fragment positioned between the femoral head and acetabulum prior to reduction, 21 (47.7%) had the fragment become intra-articular following closed reduction. All fragments that displaced into the joint were medial to the femoral head (100%) prior to closed reduction (mean age 37.4 years [18.0-77.0], 57.1% male) and 23 (52.3%) remained extra-articular (mean age 34.3 years [20.0-80.0], 65.2% male). Among intra-articular fragments, 21 of 21 (100.0%) were medial to the femoral head before reduction compared with 6 of 23 (26.1%) extra-articular fragments (p<0.001). Inferior fragment position was present in 20 of 21 (95.2%) intra-articular fragments and 8 of 23 (34.8%) extra-articular fragments (OR 37.5, 95% CI 4.2-333.1; p<0.001). Fragment length was 2.6 ± 1.1 cm versus 3.6 ± 1.0.98 cm (p=0.003). Medial fragment position was associated with non-concentric reduction (74.2% vs. 30.8%; OR 6.5, 95% CI 1.6-26.9; p=0.015), whereas inferior fragment position was not (p=0.172; OR 2.9, 95% CI 0.8-10.9; p=0.172).
CONCLUSIONS
Medial and inferior posterior wall fragment position before reduction were each associated with post-reduction intra-articular translation, while medial position was also associated with non-concentric reduction. Recognition of this morphology may aid surgical planning and anticipation of fragment retrieval.
LEVEL OF EVIDENCE
Prognostic Level IV.