Review of evolution of tunnel position in anterior cruciate ligament reconstruction

Table 1 Anatomy and evolution summary

Ref.	Study type	Results/conclusion
Petersen et al[1]	Anatomical	Describes the anatomy of ACL with histology. Describes definite landmarks of ACL attachments
Ferretti et al[2]	Cadaveric	The medial tibial eminence and the intermeniscal ligament may be used as landmarks to guide the correct tunnel placement in an anatomical ACL reconstruction
Schultz et al[8]	Histological	In this first histological demonstration of mechanoreceptors in human ACL, it seemed likely that mechanoreceptors provide proprioceptive information and contribute to reflexes inhibiting injurious movements of the knee
Schutte et al[9]	Histological	Three morphological types of mechanoreceptors and free nerve-endings were identified: two of the slow-adapting ruffini type and the third, a rapidly adapting pacinian corpuscle. Rapidly adapting receptors signal motion and slow-adapting receptors subserve speed and acceleration. Free nerve-endings, which are responsible for pain, were also identified within the ligament. These neural elements comprise 1 percent of the area of the anterior cruciate ligament
Adachi et al[11]	Histological	Positive correlation between the number of mechanoreceptors and accuracy of the joint position sense, suggesting that proprioceptive function of the ACL is related to the number of mechanoreceptors. Recommended preserving ACL remnants during ACL reconstruction
Georgoulis et al[12]	Anatomical and histological	In patients with an ACL remnant adapted to the PCL, mechanoreceptors exist even 3 yr after injury
Mae et al[17]	Cross over trial using cadaveric laboratory study	The ACL reconstruction via 2 femoral sockets using quadrupled hamstring tendons provides better anterior-posterior stability compared with the conventional reconstruction using a single socket
Strauss et al[24]	Descriptive laboratory study	During hamstring ACL reconstructions, the constraints imposed by a coupled drilling technique result in nonanatomic femoral tunnels that are superior and posterior to the native femoral insertion. Clinical relevance: Anatomic femoral tunnel placement during hamstring ACL reconstructions may not be possible using a coupled, transtibial drilling approach
Zavras et al[26]	Controlled laboratory study	Laxity was restored best by grafts tensioned to a mean of 9 ± 14 N, positioned isometrically and 3 mm posterior to the isometric point. Their tension remained low until terminal extension. Grafts 3 mm anterior to the isometric point caused significant overconstraint, and had higher tension beyond 80 degrees knee flexion
Musahl et al[30]	Controlled laboratory study	Neither femoral tunnel position restores normal kinematics of the intact knee. A femoral tunnel placed inside the anatomical footprint of the ACL results in knee kinematics closer to the intact knee than does a tunnel position located for best graft isometry
Siebold et al[18]	Cadaveric dissection Laboratory study	Clinical relevance: This study provides an anatomic description of the femoral AM and PL insertions including gender differences, landmarks, and arthroscopic orientation models for DB bone tunnel placement
Hefzy et al[31]	Cadaveric	Study found that altering the femoral attachment had a much larger effect than had altering the tibial attachment. The axis of the 2 mm region was nearly proximal-distal in orientation and located near the center of the ACL’s femoral insertion. Attachments located anterior to the axis moved away from the tibial attachment with flexion, whereas attachments located posterior to the axis moved toward the tibia
Hutchinson et al[34]	Cadaveric	The phenomenon of “resident’s ridge” is accounted for by a distinctive change in slope of the femoral notch roof that occurs just anterior to the femoral attachment of the ACL. The density change apparent at the time of notchplasty is probably caused by the transition between normal cortical thickness just anterior to the ACL and the cortical thickness of the ACL attachment. No distinctive increased cortical thickness can be identified as "resident’s ridge"-
Ferretti et al[35]	Histological and cadaveric anatomic study	The ACL femoral attachment has a unique topography with a constant presence of the lateral intercondylar ridge and often an osseous ridge between AM and PL femoral attachment, the lateral bifurcate ridge. Clinical relevance: These findings may assist surgeons to perform ACL surgery in a more anatomic fashion
Purnell et al[36]	Descriptive cadaveric study	Clinical relevance: Bony landmarks can be used to aid in anatomical anterior cruciate ligament reconstruction
Bernard et al[38]	Cadaveric anatomic study	By using this radiographic quadrant method combined with fluoroscopic control during surgery, authors were able to reinsert the ACL at its anatomic insertion site. This method is independent of variation in knee size or film-focus distance, easy to handle, and reproducible.
Colombet et al[40]	Cadaveric study	The Retro Eminence Ridge provides an easily identifiable and accurate reference point that can be used clinically. On a lateral radiograph, the positions of the tibial attachments can be referenced to Amis and Jakob's line. This method, different from Blumensaat's line, is independent of knee flexion
Amis et al[41]		A study of knee anatomy and graft placement concluded that the tibial attachment must be posterior enough to avoid graft impingement against the femur, and methods to attain this were presented

ACL: Anterior cruciate ligament; AM: Anteromedial; PL: Posterolateral.

Table 2 Biomechanics summary

Ref.	Study type	Femoral tunnelpositioning	Anatomic or isometricgraft placement	Tibial tunnelpositioning	Results
Loh et al[43]	Controlled laboratory study	Reconstructed bone-patella tendon-bone graft at the 10 and 11-o’clock position	-	-	Both the tunnel positions were equally effective under an anterior tibial load, the 10-o’clock position more effectively resists rotatory loads when compared to the 11-o’clock position
Scopp et al[45]	Controlled laboratory study	Reconstructed bone-patella tendon-bone graft at standard or oblique tunnel position	-	-	The group with the standard 30° from vertical reconstruction had significantly more laxity in internal rotation. The oblique 60° femoral tunnel more closely restored normal knee kinematics
Markolf et al[44]	Controlled laboratory study	Compared the ACL graft placed at the 11-o’clock and 9:30- to 10-o’clock femoral tunnel positions during a simulated pivot shift event	-	-	There were no significant differences in tibial rotations or tibial plateau displacements during the pivot shift between standard and oblique femoral tunnels
Musahl et al[30]	Controlled laboratory study	-	Tested cadaveric knees in response to a 134 N anterior load and a combined 10 Nm valgus and 5 Nm internal rotation load	-	A femoral tunnel placed inside the anatomical footprint of the ACL results in knee kinematics closer to the intact knee than does a tunnel position located for best graft isometry
Driscoll et al[46]	Controlled laboratory study	-	Compared femoral tunnels that were reamed through the anteromedial portal and centred alternatively in either the AM portions of the femoral footprint or the centre of the femoral footprint		Femoral tunnel positioned in the true anatomic centre of the femoral origin of the ACL may improve rotatory stability without sacrificing anterior stability
Abebe et al[47]	Controlled laboratory study	-	Compared femoral tunnels that was placed near the anterior and proximal border of the ACL and another near the centre of the ACL footprint	-	Grafts placed anteroproximally on the femur were in a more vertical orientation and therefore less likely to provide sufficient restrain. Normal orientation of the graft was better achieved with anatomical placement of the graft ultimately resulting in a more stable knee
Bedi et al[50]	Controlled laboratory study	-	-	Evaluated the effect of 3 tibial tunnel positions on restoration of knee kinematics after ACL reconstruction: over the top (non-anatomic positioning), anterior footprint and posterior footprint with a standard central femoral tunnel position at the femoral ACL footprint	Anterior positing of the tibial tunnel either in the over the top position or at the anterior foot print produces favourable kinematics than posterior positioning of the tibial tunnel. However, there is a risk of causing secondary notch impingement leading to graft attrition and failure

ACL: Anterior cruciate ligament; AM: Anteromedial.

Table 3 Clinical studies summary

Ref.	Year	Study type	Study size	Graft type	Femoral tunnel positioning	Tibial tunnel positioning	Follow-up time	Outcome measures	Results
Adebe et al[57]	2011	Retrospective cohort	22 patients	Hamstring and (BPTB)	Anatomic vs non-anatomic	-	6-36 mo	Tibial translation and rotation	Anatomic tunnel more stable in terms of anterior and medial translation and internal rotation
Alentorn-Geli et al[65]	2010	Cross-sectional comparative	47 patients	BPTB	Transtibial vs anteromedial portal techniques	-	2-5 yr	IKDC score; knee stability; ROM; one-leg hop test; mid-quadriceps circumference; VAS for satisfaction with surgery; Lysholm score; Tegner score; SF-12	From AMP technique, significantly lower recovery time from surgery to walking without crutches, return to normal life, return to jogging, training and play. Significantly better knee stability values but no difference in other functional scores surgery
Avadhani et al[69]	2010	Prospective cohort	41 patients	BPTB	-	AP position of tunnel	Minimum 2 yr	IKDC score; modified lysholm score	Placing the tibial tunnel in the anterior 25% of the tibial plateau was associated with poor knee outcomes
Behrend et al[59]	2006	Retrospective cohort	50 patients	BPTB	Position assessed using quadrant method of bernard and hertel	Position assessed using criteria of staubli and rauschning	Mean 19 mo	IKDC score	More anterior the femoral canal, highly significant correlation with poorer IKDC score. Position of the tibial tunnel had no statistically significant effect on IKDC score
Duffee et al[61]	2013[6]	Prospective cohort	436 patients	Hamstring and BPTB	Transtibial vs anteromedial portal techniques	-	6 yr	KOOS	No difference between the techniques in terms of predicting functional outcome with KOOS
Fernandes et al[60]	2014	Prospective cohort	86 patients	Hamstring and BPTB	Anteromedial footprint (anatomic) and high anteromedial position	-	6 and 12 mo	IKDC score; tegner score; lysholm scale; return to sports	Femoral tunnel positions at AM footprint and high AM position associated with earlier return to sports on previous Tegner score level and better functional outcomes at 12 mo
Franceschi et al[62]	2013	Retrospective cohort	94 patients	Hamstring	Transtibial vs anteromedial portal techniques	-	Minimum 5 yr	IKDC score; Lysholm scale; KT-1000 arthrometer; Lachman test; Pivot shift test; radiographic assessment	No difference between the two techniques in terms of functional scores (lysholm and IKDC) though the anteromedial portal technique provided better rotational and anterior translational stability
Hatayama et al[68]	2013	Prospective cohort	60 patients	Hamstring	-	AP position of tibial tunnel	2 yr	Pivot shift test; stress radiographs; 2nd look arthroscopy	Anterior placement of the tibial tunnel inside the footprint led to better anterior knee stability
Hosseini et al[58]	2012	Retrospective cohort	26 patients	Hamstring, BPTB and allograft	Non-anatomic	Non-anatomic	-	Patients undergoing revision ACL surgery: MRI based 3D modelling	Both the tibial and femoral tunnel positions in the failed ACLR were non-anatomic compared to native ACL values
Jepsen et al[55]	2007	Prospective randomised trial	60 patients	Hamstring	High (1 o’clock) vs Low (2 o’clock) positions	-	1 yr	Laxity; IKDC Evaluation and Examination forms; radiograph assessment	No significant difference in the laxity at 25 degrees and 70 degrees or scores on the IKDC examination form. Significant difference in the scores on the IKDC evaluation form
Koutras et al[64]	2013	Prospective cohort	51 patients	Hamstring	Transtibial vs anteromedial portal techniques	-	3 and 6 mo	Lysholm score; isokinetic tests; functional tests	AMP technique had significantly better suggesting a quicker return to function and performance
Noh et al[52]	2013	Prospective randomised trial	61 patients	Allograft	Transtibial vs anteromedial portal techniques	-	Mean 30.2 mo	Lachman test; pivot shift test; IKDC score; lysholm score; tegner activity scale; radiograph and MRI assessment	AMP technique resulted in a more posterior femoral tunnel position than the TT technique and knees with this technique were more stable with a higher lysholm score
Ohsawa et al[67]	2012	Retrospective cohort	121 patients	Hamstring	-	Posterior tibial landmark vs anterior tibia landmark	Minimum 2 yr	3D CT; 2nd look arthroscopy + EUA; Lachman, pivot shift and side-side stability tests; lysholm score	Pivot shift and side to side stability tests and knee flexion were significantly better in the anterior landmark group
Park et al[54]	2010	Cross-sectional	70 patients	Allograft	High (1 o’clock) vs low (2 o’clock) positions	-	Intraoperative	Intraoperative anterior and rotational knee stability at differing degrees of flexion	The low femoral tunnel group showed significantly better intraoperative internal rotational stability at 0° and 30° of flexion
Rahr-Wagner et al[63]	2013	Prospective cohort	9239 patients	-	Transtibial vs anteromedial technique	-	4 yr	Need for revision; pivot-shift and instrumented objective test	Increased risk of revision ACL surgery when using the AM technique compared with the TT technique
Sadoghi et al[56]	2011	Prospective cohort	53 knees	Hamstring and BPTB	Anatomic vs non-anatomic	Anatomic vs non-anatomic	1 yr	3D CT; Tegner score;WOMAC score; IKDC score; KT-1000 arthrometer measurements; pivot-shift test	Significantly superior clinical outcome in anatomic ACL reconstructions in terms of higher clinical scores (tegner and IKDC), higher anterior posterior stability, and less pivot shift
Seon et al[53]	2011	Prospective cohort	58 patients	Allograft	High (1 o’clock) vs low (2 o’clock) positions	-	Minimum 2 yr	Lysholm; Tegner; Clinical and radiographic stability	Low tunnel group had significantly better internal rotational stability at 0 and 30 degrees of knee flexion
Seo et al[66]	2013	Retrospective cohort	89 patients	Allograft	Transtibial vs“outside in” techniques	-	Minimum 1 yr	3D CT; pivot-shift; lachman; IKDC; lysholm; tegner; ROM	A more anatomical femoral tunnel with better knee joint rotational stability on pivot shift test
Taketomi et al[51]	2013	Case series	34 patients	Hamstring	Anatomic	-	2 yr	Lysholm score; IKDC score; KT-2000 arthrometer; lachman test; reverse pivot-shift test	Excellent short-term using the anatomic femoral tunnel objectively, subjectively and in terms of knee stability

ACL: Anterior cruciate ligament; AM: Anteromedial; TT: Transtibial; KOOS: Knee injury and osteoarthritis outcomes score; ACLR: Anterior cruciate ligament reconstruction; SF-12: Short form 12; VAS: Visual analogue scale; AP: Anter posterior; TT: Transtibial; AMP: Antero medial portal; ROM: Range of movements.