EP2.41 Biomechanical Impact of Capsulotomy on Hip Range of Motion following Periacetabular Osteotomy
Bibliographic record
Abstract
Abstract Background: Periacetabular osteotomy (PAO) aims to surgically correct hip dysplasia, restoring hip function by optimizing acetabular coverage. However, changes in acetabular positioning may alter tension forces on capsular ligaments, causing impingements or inappropriate relaxation, creating range of motion (ROM) constraints in addition to the osseous acetabular structure. The effect of capsulotomy in PAO, adapted from hip arthroscopy, and its ability to restore capsular mechanics has not yet been investigated. Purpose: To evaluate how distal iliofemoral ligament (IFL) capsulotomy following PAO influences joint ROM and kinematic stability. Methods: An experimental study, with radiographic markers implanted into medial and lateral arms of the IFL in six cadaveric hip joints was employed. ROM and joint stability were assessed in maximum flexion, external rotation (ER) of 90°, and internal rotation (IR) of 90°. Each hip underwent PAO and was retested, with preservation of capsular ligaments. Following PAO, stepwise capsulotomy was performed, preserving zona orbicularis and labrum. ROM was reassessed, and marker displacement analyzed with preoperative, postoperative, and post-capsulotomy radiographs. Joint stability was verified via hip translation, distraction, and dislocation. Paired sample t-tests compared ROM in experimental settings (CI = 95%). Results: Flexion and ER ROM demonstrated no significant change after PAO (P > 0.05). IR decreased from 16° ± 4.0° preoperatively, to 4° ± 2.5° postoperatively (P = 0.0039); reversed with inverse T-capsulotomy (P = 0.0341). Vertical capsulotomy did not significantly improve mobility planes (P > 0.05). Full H-capsulotomy increased IR (20° ± 3.2°, P = 0.0028), ER (50° ± 3.2°, P = 0.0031), and flexion (111.25° ± 8.3°, P = 0.006), but compromised stability. PAO slackened anterior and tightened inferoposterior structures. Inverted T-capsulotomy inferomedialized and anterosuperiorly translated medial and lateral radiographic markers as capsules de-tensioned. This indirectly improved ligamentous conformations of ischiofemoral and pubofemoral ligaments. Conclusions: Capsular ligament reorientation constrained functional motion in cadaveric specimens. With the balancing of femoral and acetabular anteversion, and positioning to optimize coverage, the hip capsule may be left open or loosely closed after capsulotomy without promoting iatrogenic instability. Inverted T-capsulotomy restored hip ROM, specifically IR, and may present a valuable tool in addressing functional limitations after PAO.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.002 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".