ACL Evidence Book · 8.2.1
Viewed arthroscopically at 90° of flexion, the center of the whole ACL femoral attachment lies about 6 mm on the low side of the lateral intercondylar ridge and about 2 mm deep to the bifurcate ridge; on three-dimensional CT, tunnel position is judged against a reference point at about 28%–30% depth and 35% height and by the relation of the aperture to that ridge.
Read the articleStudies agree on where the ACL attaches to the femur and tibia, but published attachment areas differ several-fold depending on which part of the attachment was measured, and center coordinates depend on the reference grid and on how the center is defined. The review percentiles and regional averages often used as targets describe study means, not individual knees, and cannot be used to judge whether a tunnel is acceptable.
AM, PL and IM are useful names for fiber regions with different positions and tension behavior. Adult anatomical studies do not establish a constant septum that divides the ACL into independently enclosed, countable bundles.
When the superficial iliotibial band and its femoral attachments remain intact, the ITB and its deep connections provide the main extra-articular restraint to internal rotation at larger flexion angles. MRI abnormalities in an individual anterolateral structure do not directly determine the clinical pivot-shift grade.
ACL force and load sharing change with flexion angle, external loading and muscle activity, with force rising near extension under several tested conditions. Attachment-site elongation, local strain and directly measured ligament force are different quantities and cannot be converted interchangeably.
Noncontact ACL injury is best explained by combined loading in several planes, while visible late collapse and reduction may follow the rupture itself. Repeated subfailure loading can also contribute to fatigue damage, although its relative contribution to injury in living athletes remains uncertain.
MRI is more reliable for detecting ACL injury than for grading a partial tear or locating the tear. Assessment of the femoral attachment, targeted oblique or flexed-knee images, and clinical laxity testing are central when imaging findings and knee function do not agree.
Treatment decisions for partial ACL tears depend on the remaining fibers’ ability to restrain anterior translation and rotation, rather than tear proportion on MRI. Nonoperative care requires scheduled reassessment of laxity and earlier review after an episode of giving way.
ACL reconstruction choices depend on tunnel placement, graft source, graft configuration, and the patient's activity demands. Autograft and bundle-number choices have stronger comparative evidence than artificial ligaments and autograft–artificial composites, whose claimed early advantages are limited by inconsistent reporting and a lack of demonstrated long-term benefit.
Peroneus longus should not be a routine first-choice graft for primary isolated ACL reconstruction, particularly for patients returning to high-intensity sport when periarticular knee autograft is available. Knee scores are often similar to those after hamstring grafting, but failure-risk comparisons remain inadequate and objective tests show ankle strength deficits.
Hamstring harvest can leave persistent weakness that depends on test position and muscle length, even when whole-range peak torque has recovered. Tendon regeneration does not establish restoration of normal muscle function, and neither a single strength threshold nor an apparently satisfactory knee score captures the full donor-site effect.
Rehabilitation after ACL reconstruction advances according to function and symptoms. Return to high-load or contact sport requires both a minimum time interval and functional criteria; a strength symmetry score alone does not establish readiness.
For primary ACL reconstruction, the author’s practice combines preincision cefazolin and graft vancomycin soaking, without postoperative antibiotics. Evidence supporting these measures differs; extending antibiotics after surgery has not shown benefit in ACL reconstruction.
CRP must be interpreted in relation to postoperative timing, symptoms, and findings in uncomplicated recovery. A normal CRP cannot exclude infection, and suspected joint infection requires prompt aspiration rather than waiting for a second CRP result.
Postoperative swelling requires early distinction between superficial ecchymosis, deep hematoma and vascular or infectious emergencies. Local treatment and rehabilitation should follow the bleeding compartment, hematoma consistency and tissue response, while routine postoperative prophylaxis should not be mistaken for treatment of an established hematoma.