Biomechanical Evidence

https://pubmed.ncbi.nlm.nih.gov/18982310/

• 👥 Patient population: 28 consecutive patients (mean age 30 years) undergoing single-bundle hamstring ACL reconstruction with over-the-top femoral fixation plus extra-articular plasty
• 📍 Study design:

In vivo, intra-operative computer-assisted navigation measured AP tibial translation at

1. 30° (Lachman)
2. 90° (drawer test)

across medial, central, and lateral compartments

• 📉 Effect of single-bundle (SB) graft:
• Reduced AP translation ~4.8 mm at 30°
• Reduced ~3.2 mm at 90°

Primary stabilizer for anterior translation

• ➕ Added effect of extra-articular (EA) plasty:
• Further reduced lateral compartment translation by 1.6 mm at 30°
• Reduced AP laxity by ~1 mm at 90°

Significant control of coupled tibial translation, especially in the lateral compartment

• 🔬 Key biomechanical insight:

Extra-articular plasty improves control of residual rotational/lateral laxity not fully addressed by single-bundle reconstruction alone

https://pubmed.ncbi.nlm.nih.gov/21710111/

• 👥 Patient population: 35 consecutive patients with isolated chronic ACL injury
• Anatomic Double-Bundle (ADB): 15 patients
• Over-the-Top Single-Bundle + Lateral Plasty (SBLP): 20 patients
• 📊 Static laxity (AP, VV, IE tests):

Both techniques significantly reduced anterior–posterior, varus/valgus, and rotational laxity.

Overall static stability was similar between groups.

• ➕ Lateral compartment control (SBLP advantage):

Extra-articular tenodesis better restrained:

1. Lateral compartment AP translation (especially at 90°)
2. Varus/valgus opening at 0° and 30°
3. Rotational displacement at 90°
• 🔄 Dynamic stability (ADB advantage):

Anatomic double-bundle reconstruction better controlled:

1. Pivot-shift phenomenon
2. Peak anterior displacement of lateral compartment
3. Hysteresis area during pivot-shift
4. Tibial reduction acceleration
• 🧠 Key insight:

Over-the-top + lateral plasty enhances peripheral/lateral compartment control

while anatomic double-bundle more closely restores dynamic rotational behavior.

https://pubmed.ncbi.nlm.nih.gov/31260843/

• 👥 Patient population: 42 patients (mean age 26 ± 8 years) with isolated ACL injury, randomized into:
• Single-Bundle (SB)
• Single-Bundle + Lateral Plasty (SBLP, over-the-top)
• Non-anatomic Double-Bundle (DB)
• 📉 All techniques reduced laxity compared to preoperative values across AP, IE, VV, and pivot-shift tests.
• 🥇 SBLP showed the greatest AP reduction at 90°

Superior to DB (p = 0.012); trend vs SB.

• 🔄 Superior rotational control (SBLP):

Greater reduction in internal–external rotation at 30° and 90° compared to both SB and DB (p < 0.05).

• 🦴 Lateral compartment restraint:

SBLP better controlled lateral tibial translation during drawer and rotational stress tests.

• 🎯 Pivot shift:

No significant difference among techniques for dynamic pivot-shift reduction.