Both low and high knee flexion angles during tibial graft fixation yield comparable outcomes following ACL reconstruction with quadriceps tendon autograft: A systematic review
Bibliographic record
Abstract
IMPORTANCE: A paucity of clinical evidence surrounds the effect of the knee flexion angle during tibial fixation of the graft during anterior cruciate ligament (ACL) reconstruction. While biomechanical studies have recently sought to revive this area of study in both single- and double-bundle graft populations, they have done so using variants of the hamstring graft. This does not shed light on the optimal fixation of other autograft options, namely, the quadriceps tendon (QT) autograft. OBJECTIVES: To determine the effect of the knee flexion angle during tibial graft fixation on functional and clinical outcomes following ACL reconstruction using single-bundle QT autograft, inclusive of both soft-tissue and bone-plug graft types. EVIDENCE REVIEW: An electronic search of MEDLINE, EMBASE, Web of Science, and the Cochrane Library was carried out from database inception to June 2020. Following study screening, patient demographics and fixation technique as well as both subjective and objective clinical outcomes were abstracted. Studies were divided based on the knee flexion angle during tibial fixation of the graft. The low knee flexion angle (L-KFA) group included patients with a tibial fixation angle of < 30° of flexion, and the high knee flexion (H-KFA) group included those with a tibial fixation of exactly 30° of flexion. The data were qualitatively synthesized due to significant heterogeneity across the included studies. FINDINGS: Sixteen studies (1,169 patients) were included for analysis. There were 675 patients in the L-KFA group (mean age range, 18.7-34.5 years) and 494 patients in the H-KFA group (mean age range, of 23.2-32.1 years). Both groups yielded statistically significant improvements from preoperative to postoperative scores across several functional and clinical outcomes. Return to pre-injury activity levels ranged from 64% to 81% in L-KFA studies and from 73.3% to 86.7% in H-KFA studies. All-cause graft failure rates ranged from 1.4% to 4.3% in L-FKA studies and from 0%-10.7% in H-KFA studies. CONCLUSION: Both low- and high-knee flexion angles during tibial graft fixation produce improved postoperative clinical and functional outcomes with comparable outcomes across groups. There is inconclusive evidence to recommend the ideal knee flexion angle for graft fixation in primary ACLR. LEVEL OF EVIDENCE: Level IV.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.008 | 0.040 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.009 | 0.009 |
| Bibliometrics | 0.008 | 0.010 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.004 | 0.002 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.002 | 0.001 |
| Insufficient payload (model declined to judge) | 0.004 | 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 source (direct Gemma or distilled Codex), 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".