Nonanatomic Anterior Cruciate Ligament Reconstruction Research Articles

Anatomical ACL Reconstruction

Dr Freddie Fu was a pioneer of sports medicine, making numerous scientific contributions that ultimately improved patient care. He was perhaps best known as a world expert on the anterior cruciate ligament (ACL). Herein we review the seminal studies of Dr Fu guiding the evolution and adoption of anatomical ACL reconstruction. From these studies, Dr Fu defined the ACL as a dynamic structure, rich in neurovascular supply and comprised of distinct bundles, which function synergistically to facilitate normal knee kinematics in concert with bony morphology. Characterized by individual uniqueness, the ACL is inherently subject to both anatomical and morphological variations as well as physiologic aging. Accordingly, anatomical ACL reconstruction entails the functional restoration of the ACL to its native dimensions, collagen orientation, and insertion sites according to individual anatomy. Anatomical ACL reconstruction has been consistently demonstrated to be superior to traditional (Ie, non-anatomical) ACL reconstruction in restoring knee stability, but graft failure and an inability to return to pre-injury sporting levels remain a challenge. In embracing the past discoveries and lessons afforded us by Dr Fu, we may embrace future efforts to improve outcomes for patients with an ACL injury.

Clinical Outcome Evaluation of Anatomic Anterior Cruciate Ligament Reconstruction With Tunnel Positioning Using Gold Standard Techniques: A Systematic Review and Meta-analysis.

Background:There have been conflicting results about the theoretical advantages of anatomic double-bundle anterior cruciate ligament (ACL) reconstruction.Purpose:To evaluate the clinical and functional outcomes comparing anatomic single- versus double-bundle techniques, anatomic versus nonanatomic techniques, and transportal versus outside-in tunnel drilling for ACL reconstruction.Study Design:Systematic review; Level of evidence, 3.Methods:A search was performed in the MEDLINE and EMBASE databases up to August 2018 for clinical trials comparing anatomic ACL reconstruction (with tunnel positioning demonstrated using gold standard radiologic techniques) with another technique, with a minimum functional and biomechanical follow-up of 6 months. A meta-analysis was performed to compare clinical and functional outcomes between anatomic single- versus double-bundle reconstruction and between anatomic versus nonanatomic techniques, using the risk difference or the mean difference. Risk of bias of the included studies was assessed using the Newcastle-Ottawa Scale for cohort and case-control studies and the Cochrane Risk of Bias tool and Jadad Score for randomized controlled trials.Results:Included were 15 studies comprising 1290 patients (follow-up, 12-36 months). No significant differences favoring anatomic double-bundle over anatomic single-bundle reconstruction or outside-in over transportal techniques were found. The meta-analyses showed significant differences in the International Knee Documentation Committee (IKDC) objective score (risk difference, –0.14; 95% confidence interval, –0.27 to –0.01) favoring anatomic over nonanatomic reconstruction. No statistically significant differences were found between anatomic and nonanatomic surgical techniques on other functional scores or clinical examination outcomes, including the IKDC subjective score, Lysholm score, Tegner score, KT-1000 arthrometer test, or pivot-shift test.Conclusion:Double-bundle reconstruction was not superior to the single-bundle technique in clinical and functional outcomes. Anatomic ACL reconstruction shows significantly superior results over nonanatomic ACL reconstruction, reinforcing the anatomic technique as the gold standard choice for clinical practice.

A Histological Comparison Between Anterior Cruciate Ligament Remnant Tissue, Anatomically Reconstructed Graft, and Non-Anatomically Reconstructed Graft.

Introduction: To our knowledge, no studies have investigated the histological comparison between primary injured anterior cruciate ligament (ACL), initially anatomically reconstructed grafts and non-anatomically reconstructed grafts at the time of revision ACL reconstruction. The purpose of this study was to histologically clarify the differences between ACL remnant tissue, reconstructed graft after anatomic double-bundle ACL reconstruction, and reconstructed graft after non-anatomic single-bundle ACL reconstruction.Methods: This histological study included five patients after anatomic double-bundle ACL reconstruction, three patients after non-anatomic single-bundle ACL reconstruction performed who injured their operated knees again, and five patients who injured their ACL for the first time and agreed to participate. All of the grafts and ACL remnant tissue were harvested, stained with hematoxylin and eosin, S-100, and alpha smooth muscle actin and evaluated using light microscopy.Results: There was no area of necrosis in the reconstructed graft after an anatomic double-bundle ACL reconstruction. However, there were obvious areas of necrosis in the reconstructed graft after non-anatomic single-bundle ACL reconstruction. Additionally, the collagen fibers were more longitudinally oriented, and most cells were spindle shaped like those in ACL remnant tissue after an anatomic double-bundle ACL reconstruction in contrast with the finding of the grafts after non-anatomic single-bundle ACL reconstruction.Conclusion: Initially reconstructed graft after an anatomic double-bundle ACL reconstruction may be beneficial if preserved at the time of the revision surgery.

Anatomic ACL reconstruction reduces risk of post-traumatic osteoarthritis: a systematic review with minimum 10-year follow-up.

To systematically review the literature for radiographic prevalence of osteoarthritis (OA) at a minimum of 10years following anterior cruciate ligament (ACL) reconstruction (ACLR) with anatomic vs. non-anatomic techniques. It was hypothesized that the incidence of OA at long-term follow-up would be lower following anatomic compared to non-anatomic ACLR. A systematic review was performed by searching PubMed, MEDLINE, EMBASE, and the Cochrane Library, for studies reporting OA prevalence by radiographic classification scales at a minimum of 10years following ACLR with autograft. Studies were categorized as anatomic if they met or exceeded a score of 8 according the Anatomic ACL Reconstruction Scoring Checklist (AARSC), while those with a score less than 8 were categorized as non-anatomic/non-specified. Secondary outcomes included graft failure and measures of knee stability (KT-1000, Pivot Shift) and functional outcomes [Lysholm, Tegner, subjective and objective International Knee Documentation Committee (IKDC) scores]. OA prevalence on all radiographic scales was recorded and adapted to a normalized scale. Twenty-six studies were included, of which 5 achieved a score of 8 on the AARSC. Using a normalized OA classification scale, 87 of 375 patients (23.2%) had diagnosed OA at a mean follow-up of 15.3years after anatomic ACLR and 744 of 1696 patients (43.9%) had OA at mean follow-up of 15.9years after non-anatomic/non-specified ACLR. The AARSC scores were 9.2 ± 1.3 for anatomic ACLR and 5.1 ± 1.1 for non-anatomic/non-specified ACLR. Secondary outcomes were relatively similar between techniques but inconsistently reported. This study showed that anatomic ACLR, defined as an AARSC score ≥ 8, was associated with lower OA prevalence at long-term follow-up. Additional studies reporting long-term outcomes following anatomic ACLR are needed, as high-level studies of anatomic ACLR are lacking. The AARSC is a valuable resource in performing and evaluating anatomic ACLR. Anatomic ACLR, as defined by the AARSC, may reduce the long-term risk of post-traumatic OA following ACL injury to a greater extent than non-anatomic ACLR. IV.

Eight-year results of transtibial nonanatomic single-bundle versus double-bundle anterior cruciate ligament reconstruction: Clinical, radiologic outcomes and survivorship.

To compare the long term outcomes of transtibial nonanatomic single-bundle (SB) and double-bundle (DB) anterior cruciate ligament (ACL) reconstruction. Between January 2008 and September 2010, we retrospectively evaluated 377 patients who underwent primary ACL reconstruction and who were available at 8 years of follow-up. Patients who received transtibial nonanatomic SB ACL reconstruction ( n = 263) were assigned to group SB and DB ACL reconstruction ( n = 114) to group DB. The patients were assessed with the International Knee Documentation Committee (IKDC), the Lysholm scores, Tegner activity score, knee joint stability tests, and patellofemoral osteoarthritis (OA) findings using the Kellgren-Lawrence (K-L) classification. Contralateral ACL (CACL) injury was also evaluated. Thirteen patients underwent revision ACL surgery during the follow-up. Ultimately, 256 patients in group SB and 108 patients in group DB were available at the 8-year follow-up. At final follow-up, the IKDC subjective score ( p = 0.04) and Lysholm score ( p = 0.02) showed significantly superior results in group DB compared to group SB. However, there was no significant difference of Tegner activity score ( p = 0.30), range of motion ( p = 0.81), and knee joint stability tests. There was significant progression of patellofemoral OA between preoperative and final follow-up in ipsilateral knee of both groups but not significant progression in contralateral knee. However, there was no significant difference between the two groups at the follow-up. There were 2.7% ipsilateral ACL graft failure in group SB, compared with 5.2% in group DB ( p = 0.12) and 6.4% CACL tear in group SB, compared with 5.2% in group DB ( p = 0.65). The mean survivorship of ACL graft was 9.47 ± 0.05 years (95% confidence interval (CI), 9.36-9.58) in group SB and 9.87 ± 0.16 years (95% CI, 9.54-10.20) in group DB, and there was no significant difference ( p = 0.25). DB ACL reconstruction resulted in significantly better clinical IKDC subjective scores and Lysholm scores. However, most of the differences in clinical scores were small, and the clinical relevance of this difference is unknown. In addition, there was no significant difference in Tegner activity score, knee joint stability tests, patellofemoral OA, and survivor rate of the ACL graft and CACL after reconstruction after a minimum of 8-year follow-up. Level of Evidence: Cohort study; level of evidence, 3.

No correlation between femoral tunnel orientation and clinical outcome at long-term follow-up after non-anatomic anterior cruciate ligament reconstruction

PurposeThis study aimed to determine the influence of femoral tunnel orientation on long-term clinical outcome and osteoarthritis in patients undergoing ACL reconstruction and to test the reliability of the implemented radiographic measurement methods. It was hypothesized that a more horizontal femoral tunnel would correlate with superior clinical outcome.MethodsA cohort of 193 patients who underwent non-anatomic ACL reconstruction was examined. In this specific study, non-anatomic is defined by the surgeons’ pursuit of optimal isometry, not to emulate the native ACL anatomy. At follow-up, the Lachman test, the KT-1000, the pivot-shift test, the one-leg-hop test and the IKDC-2000 were evaluated. Osteoarthritis was evaluated radiographically. Posteroanterior and lateral radiographs were used to determine the position of the femoral tunnel in the coronal and sagittal planes and the angle of the tunnel in the coronal plane. A method for determining femoral rotation on the lateral radiographs was developed and its reliability was evaluated. The femoral tunnel orientation was analyzed to examine its influence on clinical outcome and osteoarthritis.ResultsA total of 101 patients were analyzed at a mean of 16.4 (± 1.3) years postoperatively. The reliability of the measurement methods was regarded as good to excellent (ICC 0.57–0.97). The mean coronal femoral tunnel angle was 9.6° (± 9.4°). The coronal femoral tunnel was positioned at a mean of 43% (± 3.5%) of the distance measured from lateral to medial. The mean sagittal femoral tunnel position, measured using the quadrant method, was 40% (± 6.4%) from posterior to anterior. No significant associations were found between tunnel orientation and the clinical outcome variables.ConclusionsThe orientation of the femoral tunnel did not predict the long-term subjective outcome, functional outcome or the development of osteoarthritis in patients undergoing non-anatomic ACL reconstruction. The method for determining femoral rotation on lateral radiographs was found to be reliable.Level of evidenceRetrospective cohort study, level of evidence IV.

In vivo posterior cruciate ligament elongation in running activity after anatomic and non-anatomic anterior cruciate ligament reconstruction.

The goals of this study were to (1) investigate the in vivo elongation behaviour of the posterior cruciate ligament (PCL) during running in the uninjured knee and (2) evaluate changes in PCL elongation during running after anatomic or non-anatomic anterior cruciate ligament (ACL) reconstruction. Seventeen unilateral ACL-injured subjects were recruited after undergoing anatomic (n=9) or non-anatomic (n=8) ACL reconstruction. Bilateral high-resolution CT scans were obtained to produce 3D models. Anterolateral (AL) and posteromedial (PM) bundles insertion sites of the PCL were identified on the 3D CT scan reconstructions. Dynamic knee function was assessed during running using a dynamic stereo X-ray (DSX) system. The lengths of the AL and PM bundles were estimated from late swing through mid-stance. The contralateral knees served as normal controls. Control knees demonstrated a slight decrease in AL bundle and a significant decrease in PM bundle length following foot strike. Length and elongation patterns of the both bundles of the PCL in the anatomic ACL reconstruction group were similar to the controls. However, the change in dynamic PCL length was significantly greater in the non-anatomic group than in the anatomic reconstruction group after foot strike (p<0.05). The AL bundle length decreased slightly, and the PM bundle length significantly decreased after foot strike during running in uninjured knees. Anatomic ACL reconstruction maintained normal PCL elongation patterns more effectively than non-anatomic ACL reconstruction during high-demand, functional loading. These results support the use of anatomic ACL reconstruction to achieve normal knee function in high-demand activities. Case-control study, Level III.

Anterior Cruciate Ligament Reconstruction Using a Flexible Reamer System: Technique and Pitfalls.

Anatomic reconstruction of the anterior cruciate ligament (ACL) has been shown to improve stability of the knee, particularly rotational stability, potentially leading to superior clinical outcomes and a shorter return to sport. Nonanatomic ACL reconstruction has been linked to graft failure and abnormal cartilage loading thought to contribute to progression of degenerative joint disease. Use of the far anteromedial portal (FAMP) to uncouple the tibial and femoral tunnels has led to improved reproduction of the femoral footprint and facilitates drilling of the femoral tunnel in an anatomic position. The use of the FAMP and straight reamer systems introduces its own set of potential complications, including short femoral tunnels and peroneal nerve injury. These potential complications have been addressed by drilling the femoral tunnel in a hyperflexed position, which can lead to difficulty with positioning the operative extremity, visualization, and identification of anatomic landmarks. The purpose of this case report was to review the advantages and technical aspects of using a flexible reamer system and the FAMP to achieve an anatomic ACL reconstruction while avoiding potential complications and pitfalls. Flexible reamer systems allow an additional way of uncoupling the tibial and femoral tunnels to clearly visualize and establish an anatomic starting point within the femoral footprint of the native ACL while avoiding the complications associated with knee hyperflexion and straight reamers with the far anteromedial portal. In the authors’ experience, an anatomic reconstruction of the ACL can be achieved safely using flexible reamers while avoiding some of the difficulties seen with straight reamers used in conjunction with an uncoupled, far anteromedial approach.

Nonanatomic Anterior Cruciate Ligament Reconstruction With Double-Stranded Semitendinosus Grafts in Children With Open Physes

Background: Nonanatomic anterior cruciate ligament (ACL) reconstruction (ACLR) with double-stranded semitendinosus grafts in children with open physes has been described as a successful surgical technique in short-term follow-up clinical reports. Purpose: To evaluate the clinical outcomes of nonanatomic ACLR in children with open physes and a minimum of 15 years’ follow-up. Study Design: Case series; Level of evidence, 4. Methods: Twelve patients with an average age of 10.7 years (range, 8.3-12.4 years) underwent ACLR between 1991 and 1998. All patients were classified as Tanner development stage 2 or lower. The surgical technique involved transphyseal tibial tunnel drilling and over-the-top (OTT) femoral fixation using a double-stranded graft for all patients. Clinical outcomes were evaluated in terms of the manual Lachman test, pivot-shift test, return to sports activity, and International Knee Documentation Committee (IKDC) score at the end of growth and at a minimum 15-year follow-up (range, 15-22 years). Results: No clinically significant growth disturbance was observed. Ten patients had a grade A IKDC score, and 2 patients had a grade B IKDC score at the end of growth. There was no progression of laxity or modification of knee stability with growth. Three patients (25%) had ACL reruptures during sports activities after growth plate closure. All patients with reruptured ACLs underwent additional reconstructive surgery. Conclusion: Anterior cruciate ligament reconstruction using the OTT technique in the femur and the transphyseal technique in the tibia produces good results with regard to growth plate closure but a high failure rate in adulthood.

Knee Moment and Shear Force Are Correlated With Femoral Tunnel Orientation After Single-Bundle Anterior Cruciate Ligament Reconstruction

Background: Increasing evidence has shown that anatomic single-bundle anterior cruciate ligament reconstruction (ACLR) better restores normal knee kinematics and functionality than nonanatomic ACLR. Whether anatomic reconstruction results in better knee kinetics during daily activities has not been fully investigated. Purpose: To assess the relationship between femoral tunnel angle and kinetic parameters of the knee joint during walking after single-bundle ACLR and to compare the radiographic and kinetic results of patients who underwent anatomic ACLR with those of patients who underwent nonanatomic ACLR. Study Design: Controlled laboratory study. Methods: Twenty-one patients who underwent unilateral ACLR were recruited, and 20 healthy subjects from a previous study were used as a control group. All surgical procedures were performed by a single surgeon, 11 using the transtibial (TT) technique and 10 using the anteromedial portal (AMP) technique. Femoral tunnel orientation was measured from posterior-to-anterior radiographs. Dynamic knee joint moments and shear forces during gait were evaluated using 3-dimensional motion analysis and inverse dynamics. Relationships between femoral tunnel angles and kinetic results were evaluated via linear regression. Results were compared between 2 ACLR groups and controls using 1-way analysis of variance. Results: Femoral tunnel angle had significant correlations with peak external knee flexion moment and posterior shear force during early stance. The TT group had a significantly smaller (more vertical) mean femoral tunnel angle (19.4° ± 4.1°) than the AMP group (36.4° ± 5.8°). Significant reductions were found in the normalized peak external knee flexion moment (TT, 0.15 ± 0.12 Nm/kg·m; AMP, 0.25 ± 0.12 Nm/kg·m; control, 0.25 ± 0.16 Nm/kg·m) (P = .032) and posterior shear force (TT, 0.64 ± 0.55 N/kg; AMP, 1.10 ± 0.58 N/kg; control, 1.35 ± 0.55 N/kg) (P = .024) in the TT group compared with controls, but not in the AMP group. Moreover, a significantly greater medial shear force was found in the TT group during the late stance phase (TT, 1.08 ± 0.32 N/kg; AMP, 0.89 ± 0.26 N/kg; control, 0.83 ± 0.22 N/kg) (P = .038). A greater peak external knee adduction moment was found in both ACL groups during the early stance phase (TT, 0.25 ± 0.07 Nm/kg·m; AMP, 0.25 ± 0.07 Nm/kg·m; control, 0.19 ± 0.05 Nm/kg·m) (P < .01). Conclusion: Knee joint kinetic changes are seen within months (~10 months) after ACLR. This study revealed significant relationships between femoral tunnel orientation and postoperative knee joint flexion moment and posterior shear force during walking. The AMP technique provides better restoration of these knee kinetic parameters compared with the TT technique at this postoperative time point. Clinical Relevance: The femoral tunnel angle measured from plain radiographs can be used as an important metric of postoperative knee joint kinetics. This information provides a better understanding of the knee joint’s biomechanical environment after ACLR using commonly used single-bundle techniques.

Rotational laxity after anatomical ACL reconstruction measured by 3-D motion analysis: a prospective randomized clinical trial comparing anatomic and nonanatomic ACL reconstruction techniques.

To compare the ability of three different anterior cruciate ligament (ACL) reconstruction techniques to normalize rotational knee stability 1 year after ACL reconstruction. Two of these techniques are so-called anatomic techniques. Three different ACL reconstruction techniques were tested for their ability to normalize rotational knee stability in a prospective randomized study. Forty-seven ACL-deficient (ACLD) patients were randomized to transtibial single-bundle (SB), anatomic SB, and double-bundle ACL reconstruction. Three-dimensional motion analysis was performed preoperatively and at 1-year follow-up to evaluate tibial rotation and rotational stiffness. Motion data were captured using an eight-camera motion analysis system. Tibial rotation was determined during walking, running, and a pivoting task. Other outcome parameters were KT-1000 knee laxity measurements and the subjective outcome scores KOOS and IKDC. Three-dimensional motion analysis demonstrated that the tibial internal rotation and the rotational stiffness did not differ between the ACL reconstruction techniques during walking, running, and pivoting at 1-year follow-up. Objective knee stability and subjective outcome scores did not differ between the reconstruction groups. No significant difference in rotational stability walking, running, and pivoting was seen between anatomic and nonanatomic ACL reconstruction techniques at 1-year follow-up. Therapeutic study, Level I.

Change of the tunnel configuration in the non-anatomic trans-tibial double bundle ACL reconstruction

BackgroundThe objectives of this study were to evaluate tunnel widening and morphologic change at the tunnel aperture. MethodsA prospective study that included 17 trans-tibial double bundle anterior cruciate ligament (ACL) patients was conducted for the evaluation of serial computed tomography (CT) scan. The OsiriX® was used for remodeling of CT images with a tunnel direction. Tunnel widening and change of the aperture morphology were assessed. ResultsWith regard to the comparison of tunnel widening of the anteromedial (AM) tunnel, the entrance (p=0.01) and mid (p=0.02) of the coronal image, and the entrance (p < 0.01) and mid (p < 0.01) of the sagittal image showed statistically significant differences. The entrance (p=0.01) of the sagittal image only showed statistical significance in the posterolateral (PL) tunnel. With regard to the comparison between the AM and PL tunnels, the mid-portion (p = 0.04) of the sagittal image showed statistical differences, and the AM tunnel showed larger widening than the PL tunnel. Change of tunnel aperture was observed in the posterior, medial, and lateral portions of the AM tunnel and the anterior, posterior, and lateral portions of the PL tunnel. ConclusionsIn some aspects, occurrence of tunnel widening was observed in most sites. Widening occurred mainly at the entrance and mid-portions of the AM tunnel and the entrance of the PL tunnel. Change of tunnel aperture was observed at most directions in both tunnels. This is a non-anatomic ACL reconstruction and similar study with anatomic ACL reconstruction would be required in the future.

Anatomic and Nonanatomic Double-Bundle Anterior Cruciate Ligament Reconstruction

Background: There have been no direct in vivo biomechanical comparisons performed between an anatomic double-bundle (ADB) and a nonanatomic double-bundle (NADB) anterior cruciate ligament (ACL) reconstruction. Hypothesis: There are differences in kinematic outcomes between ADB and NADB ACL reconstruction techniques. Study Design: Controlled laboratory study. Methods: Twenty-six consecutive patients (mean age, 30 years; range, 18-32 years; 23 men, 3 women; 17 right knees, 9 left knees) with an isolated ACL injury were included in the study. The first 13 consecutive patients underwent NADB reconstruction (combination of a single-bundle and an over-the-top reconstruction), and the following 13 consecutive patients were treated with an ADB approach (using 2 tibial tunnels and 2 femoral tunnels placed in the center of the native femoral and tibial insertion sites). Grafts were pretensioned at 80 N and secured with cortical fixation systems under manual maximum force tension. Standard clinical laxity and pivot-shift tests were quantified at time zero before and after ACL reconstruction by means of a surgical navigation system dedicated to kinematic assessment; displacement of the medial and lateral compartments during the tests was also analyzed. Results: The ADB-reconstructed knees showed a larger preoperative-to-postoperative difference in anterior-posterior tibial plateau displacement of the medial and lateral compartments when compared with the NADB-reconstructed knees during the internal-external rotation test at 30° of flexion (P < .050). No other significant differences in laxity or pivot-shift values were noted. The mean surgical time for ADB reconstruction was significantly higher than that for NABD reconstruction (62 ± 13 and 43 ± 10 minutes, respectively; P < .0001). Conclusion: Results showed a greater anterior-posterior translation of both compartments during the rotational passive laxity test in the ADB reconstruction group or overconstraint caused by the NADB technique. The 2 analyzed double-bundle ACL reconstructions did not show any significant quantitative difference in isolated anterior-posterior laxity and pivot-shift phenomenon at time zero. Clinical Relevance: Nonanatomic double-bundle ACL reconstruction can control anterior-posterior laxity and the pivot-shift phenomenon as well as ABD ACL reconstruction.

The in vivo relationship between anterior neutral tibial position and loss of knee extension after transtibial ACL reconstruction

BackgroundRestoration of anterior tibial stability while avoiding knee extension deficit are a common goal of anterior cruciate ligament (ACL) reconstruction. However, achieving this goal can be challenging. The purpose of this study was to determine whether side-to-side differences in anterior tibial neutral position and laxity are correlated with knee extension deficit in subjects 2years after ACL reconstruction. MethodsIn the reconstructed and contralateral knees of 29 subjects with transtibial reconstruction, anterior tibiofemoral neutral position was measured with MRI and three-dimensional modeling techniques; terminal knee extension at heel strike of walking and during a seated knee extension were measured via gait analysis; and anterior laxity was measured using the KT-1000. ResultsKnees that approached normal anterior stability and anterior tibial position had increased extension deficit relative to the contralateral knee. On average the reconstructed knee had significantly less (2.1±4.4°) extension during active extension and during heel strike of walking (3.0±4.3º), with increased anterior neutral tibial position (2.5±1.7mm) and anterior laxity (1.8±1.0mm). There was a significant correlation between side-to-side difference in anterior neutral tibial position with both measures of knee extension (walking, r=−0.711, p<0.001); active knee extension, r=−0.544, p=0.002). ConclusionThe results indicate a relationship between the loss of active knee extension and a change in anterior neutral tibial position following non-anatomic transtibial ACL reconstruction. Given the increasing evidence of a link between altered kinematics and premature osteoarthritis, these findings provide important information to improve our understanding of in vivo knee function after ACL reconstruction.

Anatomical versus Non-Anatomical Single Bundle Anterior Cruciate Ligament Reconstruction: A Cadaveric Study of Comparison of Knee Stability

BackgroundThe purpose of this study was to compare the initial stability of anatomical and non-anatomical single bundle anterior cruciate ligament (ACL) reconstruction and to determine which would better restore intact knee kinematics. Our hypothesis was that the initial stability of anatomical single bundle ACL reconstruction would be superior to that of non-anatomical single bundle ACL reconstruction.MethodsAnterior tibial translation (ATT) and internal rotation of the tibia were measured with a computer navigation system in seven pairs of fresh-frozen cadaveric knees under two testing conditions (manual maximum anterior force, and a manual maximum anterior force combined with an internal rotational force). Tests were performed at 0, 30, 60, and 90 degrees of flexion with the ACL intact, the ACL transected, and after reconstruction of one side of a pair with either anatomical or non-anatomical single bundle ACL reconstruction.ResultsUnder manual maximal anterior force, both reconstruction techniques showed no significant difference of ATT when compared to ACL intact knee state at 30° of knee flexion (p > 0.05). Under the combined anterior and internal rotatory force, non-anatomical single-bundle ACL reconstruction showed significant difference of ATT compared to those in ACL intact group (p < 0.05). In contrast, central anatomical single bundle ACL reconstruction showed no significant difference of ATT compared to those in ACL intact group (p > 0.05). Internal rotation of the tibia showed no significant difference in the ACL intact, the ACL transected, non-anatomical reconstructed and anatomical reconstructed knees.ConclusionsAnatomical single bundle ACL reconstruction restored the initial stability closer to the native ACL under combined anterior and internal rotational forces when compared to non-anatomical ACL single bundle reconstruction.

PCL to graft impingement pressure after anatomical or non-anatomical single-bundle ACL reconstruction

Anterior cruciate ligament (ACL) graft impingement against the posterior cruciate ligament (PCL) has been postulated, but not thoroughly investigated. To evaluate PCL impingement pressure and biomechanical stability with different tibial and femoral tunnel positions in ACL reconstruction. In 15 porcine knees, the impingement pressure between ACL and PCL was measured using pressure sensitive film before and after ACL single-bundle reconstruction. ACL reconstructions were performed in each knee with three different tibial and femoral tunnel position combinations: (1) tibial antero-medial (AM) tunnel to femoral AM tunnel (AM-AM), (2) tibial postero-lateral (PL) tunnel to femoral High-AM tunnel (PL-High-AM) and (3) tibial AM tunnel to femoral High-AM tunnel (AM-High-AM). Anterior tibial translation (ATT) was evaluated after each ACL reconstruction using robotic/universal force-moment sensor testing system. There was no significant difference of the impingement pressure between AM and AM, PL-High-AM reconstructed groups and intact ACL. Only AM-High-AM ACL reconstruction group showed significantly higher impingement pressure compared with intact ACL. With regard to ATT, AM-AM group had significantly higher stiffness than PL-High-AM group. Anatomical ACL reconstruction does not cause PCL impingement and it has biomechanical advantage in ATT when compared with non-anatomical ACL reconstructions in porcine knee. For the clinical relevance, in the anatomical ACL reconstruction, no ACL-PCL impingement is found.

Anatomic Double-Bundle Anterior Cruciate Ligament Reconstruction Restores Patellofemoral Contact Areas and Pressures More Closely Than Nonanatomic Single-Bundle Reconstruction

To investigate the effects of anterior cruciate ligament (ACL) deficiency and nonanatomic single-bundle (SB) and anatomic double-bundle (DB) ACL reconstruction on the contact characteristics of the patellofemoral (PF) joint. By use of a materials testing system, 7 fresh-frozen human cadaveric knees were tested. The following states were tested: ACL-intact knee, nonanatomic SB ACL reconstruction, anatomic DB ACL reconstruction, and ACL-deficient knee. Hamstring autografts were used. PF contact pressures and areas were measured with pressure-sensitive film at 30°, 60°, and 90° of knee flexion with a constant 100-N load on the quadriceps tendon. The total contact area of ACL-deficient and nonanatomic SB ACL-reconstructed knees (123.8 ± 63.9 and 149.6 ± 79.3 mm(2), respectively) significantly decreased when compared with those of the intact knee (206.1 ± 83.6 mm(2)) at 30° of knee flexion. The lateral-facet peak pressure of ACL-deficient and nonanatomic SB ACL-reconstructed knees (1.12 ± 0.52 and 1.22 ± 0.54 MPa, respectively) significantly decreased when compared with those of the intact knee (0.68 ± 0.38 MPa) at 90° of knee flexion. Anatomic DB ACL reconstruction restored the contact pressures and areas to values similar to those of the intact knee (no significant difference). ACL deficiency resulted in a significant decrease in the total and medial PF contact areas and in an increase in the lateral PF contact pressure. Anatomic DB ACL reconstruction more closely restored normal PF contact area and pressure than did nonanatomic SB ACL reconstruction. Our findings suggest that the changes in the PF contact area and pressures in ACL deficiency and after nonanatomic SB ACL reconstruction may be one of the causes of PF osteoarthritis or other related PF problems found at long-term follow-up. Anatomic DB ACL reconstruction may reduce the incidence of PF problems by closely restoring the contact area and pressure.

A long journey to be anatomic

In 1836, Weber and Weber from Gottingen, Germany performed dissection studies and described the anterior cruciate ligament (ACL) as two separate bundles that tension at different knee flexion angles [21, 33]. Many years later in 1912, the first ACL reconstruction was performed by Giertz, the mentor of Palmer, using a single-bundle of tensor fascia lata [5]. In 1917, Hey-Groves used an open ACL reconstruction technique that was ‘‘quite’’ anatomic [9]. He used tunnels to locate the graft, drilling the femoral tunnel inside-out, aiming to place the tunnel aperture on the outer aspect of the notch to produce an oblique graft. In 1938, Palmer proposed the idea of double-bundle reconstruction in his thesis on the ACL [20], though the concept received little attention at the time and his work was not appropriately accredited until many years later. The first arthroscopically assisted ACL reconstruction was performed in 1980 by Dandy [4]. However, arthroscopic surgery was far more challenging than open reconstruction. Arthroscopic anatomic reconstruction of the ACL has a learning curve, as Snow et al. demonstrate in their paper [26]. Surgeons and industry started focusing on developing standardized techniques to facilitate easier and more efficient graft placement, employing techniques such as the o0clock reference, notchplasty, isometry and drill guides. Some of these terms like the o0clock reference and isometry turned into almost mandatory but often misleading technical descriptions. The resulting surgical techniques were indeed fast and efficient, but as Behrend et al. [2] show in their study on the over-the-top guide, unable to place the tunnels in the ACL insertion site. It was such techniques that lead the field away from the teachings of Weber, Palmer and their colleagues. Anatomic tunnel placement was not a priority, and the two-bundle anatomy of the ACL was never considered. This had surgeons asking: ‘‘Does anatomy matter?’’ since the general consensus was that these arthroscopic techniques were effective for restoring knee function. However, as longer-term follow-up data and better kinematic analysis techniques emerged, it has become clear that conventional non-anatomic ACL reconstruction techniques do not prevent the development of early osteoarthritis after ACL injury [6, 14, 16] nor do they restore normal dynamic knee function [27]. These results indicate that our reconstruction techniques need to be improved and restoring anatomy may be the key to success. Therefore, efforts to make reconstruction techniques more anatomic as well as critically evaluate them, such as by Silva et al. [24, 25] and Serrano-Fernandez et al. [23], should be applauded. ‘‘Anatomic’’ ACL reconstruction can be defined as the functional restoration of the ACL to its native dimensions, collagen orientation and insertion sites (Fig. 1) [29]. It is a detailed and meticulous procedure that involves visualization of the native ACL insertion site, measuring ACL and knee dimensions, appropriate graft tensioning and evaluation of graft and tunnel position using MRI and 3D CT scan. It encompasses singleand double-bundle reconstruction and can be applied to primary, revision and augmentation surgery. The development of the anatomic technique has made us take a closer look at the ACL anatomy. Just a few years ago, you would not have seen F. H. Fu Department of Orthopaedic Surgery, University of Pittsburgh Medical Center, Kaufman Building Suite 1011, 3471 Fifth Avenue, Pittsburgh, PA 15213, USA