Current techniques in anatomic anterior cruciate ligament reconstruction

Accessory plantaris muscle can result in symptomatic hardware impingement following ACL reconstruction

Anatomic variants of lower extremity musculature, such as the gastrocnemius, popliteus, and the plantaris have been well described in the literature. The impact of these anatomical variations on clinical outcomes depends on their proximity to and effects on adjacent anatomical structures, particularly in the context of planned surgical procedures in the region. While the presence of the accessory plantaris is rare, no previous cases have described it negatively affecting surgical outcomes to our knowledge. We present a case of a 42-year-old patient who underwent an anterior cruciate ligament (ACL) reconstruction using a femoral Endobutton for graft fixation positioned just beneath an accessory plantaris, leading to impingement and persistent knee pain. This case highlights the importance of understanding anatomical variations when planning and performing surgical procedures and suggests the need for further research in this area.

Incorporating BMP-2 and skeletal muscle to a semitendinosus autograft in an oversized tunnel yields robust bone tunnel ossification in rabbits: Toward single-step revision of failed anterior cruciate ligament reconstruction

BACKGROUND

Bone tunnel widening after anterior cruciate ligament (ACL) reconstruction is a known complication that can lead to graft failure. Subsequent revision surgery typically involves a two-stage procedure. The aim of this study was to test a novel autologous tendon graft retaining muscle tissue combined with Human Recombinant Bone Morphogenetic Protein-2 (rh-BMP-2) leading to rapid ossification of the muscle tissue, simultaneously replenishing bone stock and producing a mechanically stable bone-tendon insertion.

METHODS

In 12 skeletally mature New Zealand rabbits, the ACL was resected and oversized bone tunnels were drilled to model tunnel widening. The ipsilateral semitendinosus muscle-tendon graft was harvested and folded twice. Muscle tissue was removed in the middle third but retained at both distal ends. One side was wrapped in a collagen sponge loaded with rh-BMP-2 while the other end was used as its own control.

RESULTS

All animals were euthanized after six weeks. Micro-computed tomography (micro-CT) was used to analyze bone formation in 12 animals, with additional biomechanical testing to failure and histology performed for six animals each. Micro-CT showed that bone densities were higher by a factor of 2.4 in treated graft ends compared with their controls. Biomechanical testing showed a mean overall failure load of 37.5 N. Histology showed that the trabecular bone surrounding the implant was significantly (P = 0.0087) thicker on the treated (85.5 μm) compared with the control side (68.2 μm).

CONCLUSIONS

We conclude that a semitendinosus graft retaining the muscle tissue stimulated by recombinant Bone Morphogenetic Protein-2 (BMP-2) allows robust osseointegration of the graft within an oversized bone tunnel in an animal model.

New Trends in Anterior Cruciate Ligament Reconstruction: A Systematic Review of National Surveys of the Last 5 Years

The purpose of this study was to analyze national surveys of orthopaedic surgeons on anterior cruciate ligament (ACL) reconstruction to determine their preferences related to the preferred graft, femoral tunnel positioning, fixation and tensioning methods, antibiotic and anti-thromboembolic prophylaxis, and use of tourniquet and drains. A systematic search of PubMed, Web of Science, and Cochrane Library was performed. Inclusion criteria were surveys of ACL reconstruction trends and preferences published in the past 5 years (2011–2016), involving members of national societies of orthopaedics. Information regarding survey modalities, population surveyed, graft choice both in the general or in the athletic population, surgical technique, fixation, use of antibiotic, tourniquet, drains, and anti-thromboembolic prophylaxis was extracted. Eight national surveys were included from Europe (three), North or Latin America (three), and Asia (two). Overall, 7,420 questionnaires were sent, and 1,495 participants completed the survey (response rate ranging from 16 to 76.6%). All surveys reported the hamstring tendon (HT) autograft as the preferred graft, ranging from 45 to 89% of the surveyed population, followed by bone-patellar tendon-bone (BPTB) graft (2–41%) and allograft (2–17%). Only two surveys focusing on graft choice in athletic population underlined how in high-demand sportive population the graft choices changes in favor of BPTB. Single-bundle reconstruction was the preferred surgical technique in the four surveys that investigated this issue. Five surveys were in favor of anteromedial (AM) portal and two in favor of trans-tibial technique. Suspension devices for femoral fixation were the preferred choice in all but one survey, while interference screws were the preferred method for tibial fixation. The two surveys that investigated graft tensioning were in favor of manual tensioning. The use of tourniquet, antibiotics, drains, and anti-thromboembolic prophylaxis were vaguely reported. A trend toward the preference of HT autograft was registered in all the surveys; however, sport participation has been highlighted as an important variable for increased use of BPTB. Single-bundle reconstruction with AM portal technique and suspension femoral fixation and screws fixation for the tibia seem the preferred solution. Other variables such as tensioning, antibiotic, anti-thromboembolic prophylaxis, tourniquet use, and drains were investigated scarcely among the surveys; therefore, no clear trends could be delineated. This is a Level V, systematic review of expert opinion study.

Pseudoaneurysm of the articular branch of the descending genicular artery following double-bundle anterior cruciate ligament reconstruction

This report describes a case of a pseudoaneurysm of the articular branch of the descending genicular artery following double-bundle anterior cruciate ligament (ACL) reconstruction. An 18-year-old male received double-bundle ACL reconstruction. During ACL reconstruction, a far anteromedial portal was created for femoral tunnel drilling. The patient presented with pulsatile swelling on the medial side of the knee on the second post-operative day. The pseudoaneurysm was diagnosed using contrast computed tomography and Doppler ultrasonography and was subsequently treated by embolization with a microcatheter. Although a vascular injury is a very rare complication of knee arthroscopy, it should be considered a possibility in patients who undergo such procedures.

LEVEL OF EVIDENCE

V.

Anteromedial Portal Anterior Cruciate Ligament Reconstruction With Tibialis Anterior Allograft

In an effort to better restore normal joint function and kinematics, recent emphasis has been placed on surgical techniques that provide a more anatomic reconstruction of the anterior cruciate ligament (ACL). With femoral tunnel placement shown to play a vital role in the biomechanics, stability, and clinical outcomes after ACL reconstruction, approaches that better approximate the ACL's native femoral origin have been adopted. The independent anteromedial portal technique is thought to better position the femoral tunnel within the native ACL footprint and leave the graft more posteroinferior on the wall of the lateral femoral condyle than the more traditional transtibial approach. This article outlines the surgical technique for an anteromedial portal ACL reconstruction with a tibialis anterior allograft fixed with the Mitek Femoral and Tibial Intrafix sheath and screw system (DePuy Synthes, Raynham, MA).

Transportal Anterior Cruciate Ligament Reconstruction with Quadrupled Hamstring Tendon Graft: A Prospective Outcome Study

BACKGROUND

Anterior cruciate ligament (ACL) reconstruction has been one of the most commonly performed procedures throughout the world. Unsatisfactory outcome with conventional ACL reconstruction has been attributed to nonanatomic graft placement. Researchers have advised placing the graft in the native footprint of ACL to avoid nonanatomic graft placement. The goal of this study was to analyze the outcome of anatomic single bundle ACL reconstruction using transportal technique.

MATERIALS AND METHODS

This was a prospective outcome study conducted on 85 consecutive patients of ACL reconstruction of which 62 patients met inclusion and exclusion criteria and were analyzed for final results. All the patients underwent ACL reconstruction by quadrupled hamstring tendon graft using transportal technique and the accessory anteromedial (AAM) portal for femoral tunnel creation. The graft was fixed with endobutton on femoral side and bioabsorbable screw on the tibial side. Patients were evaluated for range of motion, International Knee Documentation Committee (IKDC) score, and Lysholm scores at a minimum followup period of 2 years. The mean pre- and postoperative scores were compared using Wilcoxon signed-rank test.

RESULTS

The mean Lysholm and IKDC scores improved significantly (P < 0.0001) from preoperative value. According to IKDC score, 90.3% (n = 56) were either normal or near normal at final followup. According to Lysholm score, 75.8% of patients had excellent and 13.3% had good results. Preoperatively, pivot shift was present in 85.5% (n = 53) of patients which reduced to 4.8% (n = 3) postoperatively. Infection and knee stiffness occurred in two patients, and femoral tunnel blowout and graft re-rupture occurred in one patient each.

CONCLUSION

Anatomic ACL reconstruction by AAM portal is a reproducible technique which gives good clinical outcome at short-term followup.

Biomechanics of the anterior cruciate ligament: Physiology, rupture and reconstruction techniques

The influences and mechanisms of the physiology, rupture and reconstruction of the anterior cruciate ligament (ACL) on kinematics and clinical outcomes have been investigated in many biomechanical and clinical studies over the last several decades. The knee is a complex joint with shifting contact points, pressures and axes that are affected when a ligament is injured. The ACL, as one of the intra-articular ligaments, has a strong influence on the resulting kinematics. Often, other meniscal or ligamentous injuries accompany ACL ruptures and further deteriorate the resulting kinematics and clinical outcomes. Knowing the surgical options, anatomic relations and current evidence to restore ACL function and considering the influence of concomitant injuries on resulting kinematics to restore full function can together help to achieve an optimal outcome.

Review of evolution of tunnel position in anterior cruciate ligament reconstruction

Anterior cruciate ligament (ACL) rupture is one of the commonest knee sport injuries. The annual incidence of the ACL injury is between 100000-200000 in the United States. Worldwide around 400000 ACL reconstructions are performed in a year. The goal of ACL reconstruction is to restore the normal knee anatomy and kinesiology. The tibial and femoral tunnel placements are of primordial importance in achieving this outcome. Other factors that influence successful reconstruction are types of grafts, surgical techniques and rehabilitation programmes. A comprehensive understanding of ACL anatomy has led to the development of newer techniques supplemented by more robust biological and mechanical concepts. In this review we are mainly focussing on the evolution of tunnel placement in ACL reconstruction, focusing on three main categories, i.e., anatomical, biological and clinical outcomes. The importance of tunnel placement in the success of ACL reconstruction is well researched. Definite clinical and functional data is lacking to establish the superiority of the single or double bundle reconstruction technique. While there is a trend towards the use of anteromedial portals for femoral tunnel placement, their clinical superiority over trans-tibial tunnels is yet to be established.

Influences of knee flexion angle and portal position on the location of femoral tunnel outlet in anterior cruciate ligament reconstruction with anteromedial portal technique

PURPOSE

To evaluate the influences of knee flexion angle and portal position on the location of femoral tunnel outlet in anterior cruciate ligament (ACL) reconstruction with the anteromedial (AM) portal technique.

METHODS

We recruited 6 volunteers with 12 normal knees. Each knee was flexed 120° or 135° and scanned with an open MRI. A 3D knee model was created. Virtual femoral tunnels were created on the footprint of the AM bundle and the posterolateral (PL) bundle of the ACL from three arthroscopic portals: the standard AM portal, the far medial and low portal, and the far medial and high (FMH) portal. The location of the femoral tunnel outlet was evaluated by comparing to the dissected cadaveric knee.

RESULTS

Both increased flexion angle and lowering the drilling portal have a similar influence on the femoral tunnel outlet by moving them anterior and distally. Medialization of the portal moves them posteriorly and distally. PL tunnels created on the 120° knee model are more likely to be located under the lateral head of the gastrocnemius especially when they are drilled through the AM or FMH portals.

CONCLUSION

If the femoral tunnel outlet is located under the soft tissue such as gastrocnemius attachment, suspension fixation devices may lapse into fixation failure by sitting on the soft tissue rather than the cortex bone surface. It is more desirable to drill in 135° knee flexion rather than 120°, and through a lower portal, to avoid creating the femoral tunnel outlet under soft tissues.

Three-dimensional computed tomography evaluation of anterior cruciate ligament footprint for anatomic single-bundle reconstruction

PURPOSE

Femoral and tibial footprint coordinates have been well studied in double-bundle anterior cruciate ligament (ACL) reconstruction. However, in a single-bundle reconstruction approach, the central coordinate of femoral and tibial footprints have not been determined. The purpose of this study was to describe the central point locations of the ACL footprints visualized by three-dimensional computed tomography (3D CT) images and analysed by the quadrant method.

METHODS

Eight cadaveric knees were dissected, and the central points of ACL femoral and tibial footprints were marked and analysed using 3D CT images.

RESULTS

In the present study, the means (and standard deviation) of ACL femoral footprint dimensions were in the ventral-dorsal plane and in the cranial-caudal plane 9.4 ± 0.8 and 15.6 ± 0.9 mm, respectively. In the tibial side, the means of ACL footprint dimensions were in the anterior-posterior and in the medial-lateral 18.5 ± 1.9 and 15.5 ± 1.0 mm, respectively. In the tomographic analyses, the means of femoral central location coordinates in the ventral-dorsal (y) and in the cranial-caudal (x) axes were 35.3 ± 4.5 and 30.0 ± 1.6 %, respectively. The means of tibial central location coordinates were in the anterior-posterior (y) and in the medial-lateral (x) axes, respectively: 40.5 ± 5.3 and 50.2 ± 1.3 %, respectively.

CONCLUSIONS

These computed tomographic coordinates might help future studies as a reference on ACL single-bundle anatomic reconstruction, with respect to the management of ACL revision surgery or in symptomatic patients after ACL reconstruction. Improvements in three-dimensional image acquisition could facilitate its intraoperative applicability in the coming years.

Clinical and three-dimensional computed tomographic comparison between ACL transportal versus ACL transtibial single-bundle reconstructions with hamstrings

BACKGROUND

Anterior cruciate ligament (ACL) reconstruction using a single-bundle transtibial technique can achieve good or excellent results in more than 90% of patients, but anatomical and biomechanical studies have questioned its ability to restore knee function. The purpose of this study was to evaluate clinical and tomographic results (patient satisfaction, knee function, and tunnel location) of patients who underwent transportal or transtibial single-bundle ACL reconstruction.

METHODS

Seventy-one patients with ACL tears were included. Forty-one patients were treated by the single-bundle transportal technique and 30 patients were treated by the single-bundle transtibial technique. Clinical and tomographic data were analyzed in both groups.

RESULTS

After a minimum of 2-year period, the transportal group showed more patients with normal clinical tests than the transtibial group (Lachman [p=0.037], pivot shift [0.00], anterior drawer [0.002]; and arthrometer [0.002] tests). Regarding CT evaluation, transportal and transtibial groups obtained the following femoral central tunnel location (mean [SD]), as percentage: 30 (6.5) and 4.2 (6.4) in high-low axis; and 30.9 (5.9) and 33.2 (4.6) in the deep-shallow axis. Values in the tibial side were, respectively: 38 (6.5) and 46.0 (6.8) in the anterior-posterior axis; and 47.2 (2.5) and 46.9 (2.1) in the medial-lateral axis.

CONCLUSION

CT findings showed that the transportal single-bundle technique positions the ACL tunnel closer to the native ACL footprint in both femur and tibia compared with the transtibial single-bundle technique. Moreover, mild asymptomatic instability and extension deficit were observed more often in the transtibial group.

A Three-Dimensional Evaluation of EndoButton Displacement Direction After Anterior Cruciate Ligament Reconstruction in CT Image Using Tunnel Axis

The goal of this study was to propose a threedimensional evaluation of the EndoButton displacement direction after anterior cruciate ligament reconstruction in the multidetector-row computed tomography (MDCT) image by using the tunnel axis. The proposed method was applied experimentally to six subjects. The result of the simulated experiment revealed that the proposed method could analyze EndoButton displacement direction satisfactorily because the error was less than that of the MDCT image resolution. The clinical experiment results revealed displacement relative to the tunnel between time-zero and the followup point. We conclude that the proposed method can quantitatively evaluate the EndoButton displacement direction from the raw MDCT image after anterior cruciate ligament reconstruction; further, our findings suggest that the EndoButton was displaced relative to the tunnel between time-zero and the follow-up point.

Tibial tunnel placement accuracy during anterior cruciate ligament reconstruction: independent femoral versus transtibial femoral tunnel drilling techniques

PURPOSE

This study aimed to compare the accuracy of tibial tunnel placement using independent femoral (IF) versus transtibial (TT) techniques.

METHODS

Ten matched pairs of cadaveric knees were randomized so that one knee in the pair underwent arthroscopic TT drilling of the femoral tunnel and the other underwent IF drilling through an accessory medial portal. For both techniques, an attempt was made to place the femoral and tibial tunnels as close to the center of the respective anterior cruciate ligament (ACL) footprints as possible. Preoperative and postoperative computed tomography using a technique optimized for ligament evaluation allowed comparison of the anatomic ACL tibial footprint to the tibial tunnel aperture. The percentage of tunnel aperture contained within the native footprint, as well as the distance from the center of the tunnel aperture to the center of the footprint, was measured. Additionally, graft obliquity relative to the tibial plateau was evaluated in the sagittal plane.

RESULTS

The percentage of tibial tunnel aperture contained within the native footprint averaged 71.6% ± 17.2% versus 52.1% ± 23.4% (P = .04) in the IF and TT groups, respectively. The distance from the center of the footprint to the center of the tibial tunnel aperture was 3.50 ± 1.6 mm and 4.40 ± 1.7 mm (P = .27) in the IF and TT groups, respectively. TT drilling placed 6 of 10 tunnels posterior to the center of the footprint versus 3 of 10 tunnels in IF drilling. The graft obliquity angles were 54.8° in TT specimens and 47.5° in IF specimens (P = .09).

CONCLUSIONS

This study adds to the literature suggesting that TT drilling with an 8-mm reamer has deleterious effects on tibial tunnel aperture and position. IF drilling, which does not involve repeated reaming of the tibial tunnel, is associated with the placement of a higher percentage of the tunnel aperture within the native tibial footprint. There was not a significant difference between the IF and TT techniques in their ability to place the center of the tibial aperture near the center of the footprint or in graft obliquity.

CLINICAL RELEVANCE

ACL reconstruction has continued to evolve in an attempt to restore the functional anatomy and biomechanical behavior of the knee. Tibial tunnel characteristics-such as location, aperture topography, and tunnel obliquity-are important factors to consider in ACL reconstruction. This study compares tibial tunnels after IF and TT techniques.

Simulated anterior cruciate ligament reconstruction using preoperative three-dimensional computed tomography

PURPOSE

The aim of this study was to ascertain the ideal far anteromedial portal location to avoid damaging the medial femoral condyle in anterior cruciate ligament (ACL) reconstruction.

METHODS

Forty patients received preoperative computed tomography (CT) scans at 120° of knee flexion. Three-dimensional CT (3D CT) reconstruction of the knee was performed using volume rendering. The insertion of anteromedial (AM) and posterolateral bundle of ACL of the femur was marked on the 3D CT. A line (Line A) was drawn 8-mm proximal and parallel to the anterior ridge of the medial tibial plateau. A tangential line to the medial femoral condyle was drawn from the AM position that was already marked to Line A. The length from the intersection of the lines to the medial edge of the patellar tendon was measured.

RESULTS

In all 40 patients, the mean length between the medial edge of the patellar tendon and the far anteromedial portal was 27.5 ± 0.7 mm (range 19.8-34.5). In men 29.5 ± 0.7 mm (range 25-34.5); 28.7 ± 0.8 mm in the shorter group (height ≤ 170 cm) and 30.1 ± 1.2 mm in the taller group (height ≥ 170 cm). In women 25.5 ± 1.0 mm (range 19.8-30.5); 22.9 ± 1.0 mm in the shorter group (height ≤ 158 cm) and 29.6 ± 0.5 mm in the taller group (height ≥ 158 cm).

CONCLUSIONS

An optimum far anteromedial portal position was proposed. Knowing the optimum location of the far anteromedial portal position before surgery allows the surgeons to perform more safety ACL reconstruction.

LEVEL OF EVIDENCE

IV.

Anatomic single-bundle ACL surgery: consequences of tibial tunnel diameter and drill-guide angle on tibial footprint coverage

PURPOSE

To investigate the consequences of differences in drill-guide angle and tibial tunnel diameter on the amount of tibial anatomical anterior cruciate ligament (ACL) footprint coverage and the risk of overhang of the tibial tunnel aperture over the edges of the native tibial ACL footprint.

METHODS

Twenty fresh-frozen adult human knee specimens with a median age of 46 years were used for this study. Digital templates mimicking the ellipsoid aperture of tibial tunnels with a different drill-guide angle and a different diameter were designed. The centres of these templates were positioned over the geometric centre of the tibial ACL footprint. The amount of tibial ACL footprint coverage and overhang was calculated. Risk factors for overhang were determined. Footprint coverage and the risk of overhang were also compared between a lateral tibial tunnel and a classic antero-medial tibial tunnel.

RESULTS

A larger tibial tunnel diameter and a smaller drill-guide angle both will create significant more footprint coverage and overhang. In 45% of the knees, an overhang was created with a 10-mm diameter tibial tunnel with drill-guide angle 45°. Furthermore, a lateral tibial tunnel was found not to be at increased risk of overhang.

CONCLUSION

A larger tibial tunnel diameter and a smaller drill-guide angle both will increase the amount of footprint coverage. Inversely, larger tibial tunnel diameters and smaller drill-guide angles will increase the risk of overhang of the tibial tunnel aperture over the edges of the native tibial ACL footprint. A lateral tibial tunnel does not increase the risk of overhang.

Biomechanics of single-tunnel double-bundle anterior cruciate ligament reconstruction using fixation with a unique expandable interference screw

BACKGROUND

Single-tunnel double-bundle (STDB) anterior cruciate ligament (ACL) reconstruction can restore biomechanical function and anatomic structure, but existing methods of graft fixation are not adequate. The aims of this study are to examine knee biomechanics after STDB reconstruction using a unique expandable interference screw for fixation.

METHODS

The biomechanical parameters of six pairs of human cadaveric knee specimens were measured with the ACL intact, after ACL removal, and after STDB reconstruction using the interference screw or single-tunnel single-bundle (STSB) reconstruction. Anterior tibial translation under 134 N anterior tibial load in a neutral position as well as in 15° and 30° internal and external knee rotation and the internal tibial rotation angle under the rotatory load (5 N·m internal tibial rotation) were measured.

RESULTS

Anterior tibial translations at each degree of knee flexion in the STDB group were significantly less than in the STSB group (all, P<0.05). The internal rotation angles in the STSB group at five flexion angles were significantly higher than in the ACL intact group, whereas there were significantly less than those of the ACL absent group (P<0.05). Under rotatory loads in the neutral position, the tibial internal rotation angles of the STDB group were significantly lower than in the STSB group at all flexion angles (all, P<0.05).

CONCLUSIONS

STDB ACL reconstruction with the expandable interference screw provides better anteroposterior and rotational stability than STSB reconstruction.

CLINICAL RELEVANCE

The technique provides the advantages of double-bundle reconstruction using a single-tunnel technique.

Anatomic and nonanatomic double-bundle anterior cruciate ligament reconstruction: an in vivo kinematic analysis

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.

Can a tibial tunnel in ACL surgery be placed anatomically without impinging on the femoral notch? A risk factor analysis

PURPOSE

To analyze anatomical risk factors and surgical technique dependent variables, which determine the risk for femoral notch impingement in anatomically correct placed tibial tunnels for anterior cruciate ligament (ACL) surgery.

METHODS

Twenty fresh frozen adult human knee specimens under the age of 65 years were used. Digital templates mimicking a tibial tunnel aperture at the tibia plateau were designed for different tibial tunnel diameters and different drill-guide angles. The centres of these templates were placed over the geometric centre of the native tibial ACL footprint. The distances between the anterior borders of the templates and the anterior borders of the footprints (graft free zone) were measured and compared. Furthermore, anatomic risk factors for femoral notch impingement were determined.

RESULTS

The graft free zone was statistically significantly longer for larger drill-guide angles compared to smaller drill-guide angles (p < 0.00001). Furthermore, 8 mm diameter tibial tunnels had a statistically significant larger graft free zone compared to 10-mm-diameter tibial tunnels (p < 0.00001). For the 10 mm diameter tibial tunnels with drill-guide angle of 45°, 9 out of 20 knees (45 %) were "at risk" for notching and 4 out of 20 knees (20 %) had "definite" notching. For 10-mm tunnels with drill-guide angle of 45°, a risk for notching was associated with smaller tibial ACL footprint (p < 0.05).

CONCLUSION

If a perfect centrally positioned tibial tunnel is drilled, a real risk for femoral notch impingement exists depending on the size of the tibial ACL footprint and surgery-related factors. Therefore, in anatomical tibial tunnel placement in single bundle ACL reconstruction surgery, particular attention should be paid to size of the tunnel and drill-guide angle to minimize the risk of femoral notch impingement.

Far anteromedial portal technique for posterolateral femoral tunnel drilling in anatomic double-bundle anterior cruciate ligament reconstruction: a cadaveric study

PURPOSE

To identify the relationship between knee flexion angle and femoral tunnel length, as well as the exit points of guidewires, when using a far anteromedial portal technique for posterolateral femoral tunnel drilling in double-bundle anterior cruciate ligament reconstruction.

METHODS

Using the far anteromedial portal technique in 8 cadaveric knees, femoral tunnel drilling for the posterolateral bundle was performed at 3 knee flexion angles: 90°, 110° and 130°. We measured the femoral tunnel length and the distances from each guidewire to the closest relevant structures.

RESULTS

The mean tunnel length at 90° knee flexion (25.8 ± 1.8 mm) was significantly shorter than the length at 110° and 130° knee flexion (32.1 ± 2.6 and 33.1 ± 2.5 mm, respectively). The average distance between the exit point of the guidewire and the posterior articular cartilage of the lateral femoral condyle was the shortest at 90° knee flexion (3.3 ± 2.2 mm). The distance between the guidewire and the centre of the origin of the lateral collateral ligament was the shortest at 130° knee flexion (8.0 ± 1.8 mm). The guidewires penetrated the origin of the lateral gastrocnemius tendon in 2 cases at 110° knee flexion and in 1 case each at 90° and 130° knee flexion.

CONCLUSIONS

When using the far anteromedial portal technique, more than 110° knee flexion is desirable to achieve ideal femoral tunnel length and avoid articular cartilage injury. In addition, the risk of damage to the origin of the lateral collateral ligament increases when the knee flexion angle increases to 130°. A knee flexion angle between 110° and 120° was recommended when using the far anteromedial portal technique.

Transtibial ACL femoral tunnel preparation increases odds of repeat ipsilateral knee surgery

BACKGROUND

Recent efforts to improve the results of anterior cruciate ligament (ACL) reconstruction have focused on placing the femoral tunnel anatomically. Medial portal femoral tunnel techniques facilitate drilling of femoral tunnels that are more anatomic than those made with transtibial techniques. Few studies have compared the clinical outcomes of these two femoral tunnel techniques. We hypothesized that the transtibial technique is associated with decreased Knee injury and Osteoarthritis Outcome Scores (KOOS) and an increased risk of repeat surgery in the ipsilateral knee when compared with the anteromedial portal technique.

METHODS

Four hundred and thirty-six patients who had undergone primary isolated autograft ACL reconstruction with a transtibial (229 patients) or anteromedial portal (207 patients) technique in 2002 or 2003 were identified in a prospective multicenter cohort. A multiple linear regression model was used to determine whether surgical technique (transtibial or anteromedial portal) was a significant predictor of KOOS at six years postoperatively, after controlling for preoperative KOOS, patient age, sex, activity level, body mass index (BMI), smoking status, graft type, and the presence of meniscal and chondral pathology at the time of reconstruction. A multiple logistic regression model was used to determine whether surgical technique was a significant predictor of repeat ipsilateral knee surgery, after controlling for patient age and activity level, graft type, and meniscal pathology at the time of reconstruction.

RESULTS

Postoperative KOOS were available for 387 patients (88.8%). Femoral tunnel drilling technique was not a predictor of the KOOS Quality of Life subscore (p = 0.72) or KOOS Function, Sports and Recreational Activities subscore (p = 0.36) at the six-year follow-up evaluation. Data regarding the prevalence of repeat surgery were available for 380 patients. Femoral tunnel technique was a significant predictor of subsequent ipsilateral knee surgery (odds ratio [OR] = 2.49, 95% confidence interval [CI] = 1.30 to 4.78, p = 0.006).

CONCLUSIONS

Patients who underwent ACL reconstruction with a transtibial technique had significantly higher odds of undergoing repeat ipsilateral knee surgery relative to those who underwent reconstruction with an anteromedial portal technique.

Long-term results after reconstruction of the ACL with hamstrings autograft and transtibial femoral drilling

PURPOSE

To evaluate the long-term clinical, patient-reported and radiological outcome of patients reconstructed for anterior cruciate ligament (ACL) insufficiency. We wanted to examine the relationship between clinical findings and patient-reported scores.

METHODS

The 96 first successive patients that underwent ACL reconstruction using transtibial technique, hamstrings autograft and tunnel placement ad modum Howell were evaluated 10 years post-operatively. Subjective outcomes were Lysholm score, IKDC 2000 subjective score and Tegner activity scale. The clinical examination included evaluation of rotational and sagittal laxity. Evaluation of osteoarthritis was done radiologically.

RESULTS

Eighty-three patients (86%) were available for follow-up at mean 10.2 years post-operatively. Three patients had revision ACL surgery prior to the 10-year evaluation. The mean Lysholm score, subjective IKDC 2000 score and Tegner activity scale were 89 (SD 13), 83 (SD 15) and 5 (range, 3-9), respectively. Six patients (8%) had moderate or severe osteoarthritis. Eighty-six per cent of patients had normal or near-normal anterior-posterior ACL laxity. Twenty per cent of patients had positive pivot shift and 42 % had a pivot glide. The former group had a significant lower Lysholm score compared to the rest of the patients.

CONCLUSIONS

Although the mean Lysholm score was classified as good (89) at the 10-year follow-up, a positive pivot shift was found in 20% of these patients. Compared to patients with normal rotational laxity or pivot glide, this patient group reported significant lower subjective satisfaction at the long-term follow-up.

LEVEL OF EVIDENCE

Case series, level IV.

Anteromedial portal versus transtibial drilling techniques in anterior cruciate ligament reconstruction: any clinical relevance? A retrospective comparative study

PURPOSE

This study aimed to undertake a retrospective analysis of prospectively collected data comparing, at a minimum follow-up of 5 years (78.1 ± 5.3 months v 75.6 ± 4.8 months), the clinical, functional, and radiographic outcomes of 2 homogeneous groups of athletes who had undergone arthroscopic single-bundle autologous hamstring reconstruction of the anterior cruciate ligament (ACL) using a transtibial (TT) or an anteromedial portal (AMP) approach to drill the femoral tunnel.

METHODS

Ninety-four patients were operated on in 2005 and 2006, and 88 (93.6%) (73 men, 15 women) were evaluated subjectively and objectively, using the Lysholm and International Knee Documentation Committee (IKDC) scores, manual maximum displacement test with a KT-1000 arthrometer (MEDmetric, San Diego, CA) and the Lachman test, and rotational instability with the pivot shift test. Degenerative changes were assessed on radiographs according to the Fairbank classification.

RESULTS

The median age at operation was 29 years (20 to 43 years; SD, 5.4) in the TT group 1 and 28 years (19 to 45 years; SD, 6.1) in the AMP group 2. At the last appointment, the 2 groups had similar results for the Lysholm and IKDC scores (primary outcome). Patients who underwent the AMP approach had less glide pivot shift (P = .42) and Lachman (P = .47) phenomena, with no statistically significant intergroup difference. Radiography showed fewer, but not significantly different, degenerative changes in the AMP ACL reconstruction group at final follow-up (P = .47).

CONCLUSIONS

In our series, ACL reconstruction using a femoral tunnel drilled through an AMP provided better rotational stability and anterior translation than drilling the femoral tunnel using the TT technique. This difference likely is not relevant from a clinical and functional viewpoint. The 2 groups of patients were not significantly different in terms of development of degenerative changes seen radiographically at a minimum follow-up of 5 years.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

Double-bundle anterior cruciate ligament reconstruction with split Achilles allograft and single tibia tunnel for small ACL tibial footprint : technical note with clinical results

PURPOSE

We describe a surgical technique of double-bundle ACL reconstruction with a single tibia tunnel and report the clinical outcome.

METHODS

The Achilles tendon portion was split longitudinally into two separate bundles, namely, an anteromedial (AM) bundle with 7-8 mm diameter and a posterolateral (PL) bundle with 4-6 mm diameter. The central portion of the calcaneal bone plug was prepared with a diameter of 10 mm and a length of 30 mm. For the femoral tunnel preparation, we preferred inside out target through an accessory anteromedial portal for an approach to native ACL footprint and outside in reaming through separate incision on the lateral aspect of distal thigh to prevent cartilage injury of medial femoral condyle. 10 mm diameter of single tibia tunnel was prepared at the central portion of ACL tibial footprint. After graft passage from tibia to femoral side, fixation of calcaneal bone plug within the tibia tunnel was performed using two bioabsorbable cross pins. Then, AM bundle was first fixed at 45° of flexion while the PL bundle was fixed at 10° of flexion using bioabsorbable interference screws and augmented staples. Clinical results of 22 patients (18 males and 4 females, average age 30.7 years) who underwent double-bundle anterior cruciate ligament (ACL) reconstruction with this technique were evaluated.

RESULTS

At an average follow-up of 30 months, there was significant improvement of the Lysholm knee score, the 2,000 IKDC subjective knee score, the median Tegner activity score and the side-to-side difference. According to the 2,000 IKDC knee examination form, the grade rated as normal in seven patients, nearly normal in 14 patients and abnormal in one patient at the latest follow-up. There were no postoperative complications and revisional surgeries.

CONCLUSIONS

Split Achilles allograft and single tibia tunnel technique for double-bundle ACL reconstruction can be an alternative option for patients with small tibial insertion sites.

LEVEL OF EVIDENCE

Level IV, therapeutic study.

Effect of ACL reconstruction tunnels on stress in the distal femur

PURPOSE

This study examined the change in femoral stress caused by graft tunnels drilled for anterior cruciate ligament (ACL) reconstruction. Using a computational model, the number, geometry and position of the graft tunnels exits were varied to determine the effect on bone stress.

METHODS

A finite element model of the distal femur was developed from a CT scan of a cadaveric knee. To assess the model, the strain calculated computationally was compared to experimentally measured strains in eleven unpaired human cadaver femurs. Using the computational model, the number, geometry and position of the graft tunnel exits were varied to determine the effect on bone stress based on the stress concentration factor: the ratio of bone stress with tunnels to intact bone stress.

RESULTS

The results indicated that the second tunnel in double-bundle ACL reconstruction results in approximately a 20 % increase in the maximum femoral stress as compared to single-bundle reconstruction. The highest stresses occur at the tunnel exits. The position of the tunnel exits effects femoral stress with the stress increasing slightly (AM SCR from 0.7 to 1 and PL SCR from 1.2 to 1.3) when the AM tunnel exit is moved anteriorly and having greater increases as the posterior lateral (PL) tunnel exit is moved laterally (PL SCR from 1.2 to 1.7) or posteriorly (PL SCR from 1.2 to 2).

CONCLUSION

In anatomical ACL reconstruction, the tunnel entrances are dictated by anatomy; however, there can be variations in tunnel exit positions. Consideration should be given when positioning tunnel exits on the effect on stress in the femur. Moving the PL tunnel exit laterally or posteriorly increases in the stress at the PL tunnel exit.

Anterior cruciate ligament reconstruction femoral tunnel characteristics using an accessory medial portal versus traditional transtibial drilling

PURPOSE

To evaluate anterior cruciate ligament femoral tunnel characteristics using an accessory medial (AM) portal and transtibial (TT) drilling.

METHODS

Ten matched pairs of cadaveric knees underwent arthroscopic AM portal or TT femoral drilling with 8-mm reamers. All knees underwent computed tomography scanning and were evaluated for tunnel aperture area, shape as described by the length of the long and short axes, location of the tunnel relative to the anterior and inferior aspects of the articular surface with the knee in extension, tunnel angle in the coronal and axial planes, and tunnel length.

RESULTS

The femoral tunnel aperture area was 50.5 ± 4.8 mm(2) for AM portal drilling and 51.9 ± 4.6 mm(2) for TT drilling (P = .5). The femoral tunnel aperture long axis was 8.5 ± 1.1 mm for AM portal drilling and 9.2 ± 1.3 mm for TT drilling (P = .2), and the short axis was 8.0 ± 0.5 mm for AM portal drilling and 8.0 ± 0.5 mm for TT drilling (P = .8). The femoral tunnel aperture was 5.0 ± 1.4 mm from the anterior wall for AM portal drilling and 9.9 ± 1.7 mm for TT drilling (P < .001), and it was 7.6 ± 2.4 mm from the inferior articular surface for AM portal drilling and 8.9 ± 2.2 mm for TT drilling (P = .2). The femoral tunnel orientation in the coronal plane was 42.1° ± 4.8° for AM portal drilling and 60.9° ± 6.7° for TT drilling (P < .001), and the orientation in the axial plane was 20.9° ± 4.4° for AM portal drilling and 22.7° ± 13.5° for TT drilling (P = .7). The femoral tunnel length was 35.6 ± 2.8 mm for AM portal drilling and 40.3 ± 7.9 mm for TT drilling (P = .1).

CONCLUSIONS

The use of an AM portal creates a tunnel more anterior and more horizontal than tunnels created by a TT technique.

CLINICAL RELEVANCE

The femoral tunnel characteristics may have an effect on the strain placed on the graft, the graft bending angle, whether enough graft can be placed into the tunnel, and, ultimately, the ability of the body to fully heal the graft.

Anatomic femoral tunnel drilling in anterior cruciate ligament reconstruction: use of an accessory medial portal versus traditional transtibial drilling

BACKGROUND

During anatomic anterior cruciate ligament (ACL) reconstruction, we have found that the femoral footprint can best be visualized from the anteromedial portal. Independent femoral tunnel drilling can then be performed through an accessory medial portal, medial and inferior to the standard anteromedial portal.

PURPOSE

To compare the accuracy of independent femoral tunnel placement relative to the ACL footprint using an accessory medial portal versus tunnel placement with a traditional transtibial technique.

STUDY DESIGN

Controlled laboratory study.

METHODS

Ten matched pairs of cadaveric knees were randomized such that within each pair, one knee underwent arthroscopic transtibial (TT) drilling, and the other underwent drilling through an accessory medial portal (AM). All knees underwent computed tomography (CT) both preoperatively and postoperatively with a technique optimized for ligament evaluation (80 keV with maximum mAs). Computed tomography was performed with a dual-energy scanner. Commercially available third-party software was used to fuse the preoperative and postoperative CT scans, allowing anatomic comparison of the ACL footprint to the drilled tunnel. The ACL footprint was marked in consensus by an orthopaedic surgeon and a musculoskeletal radiologist and then compared with the tunnel aperture after drilling. The percentage of tunnel aperture contained within the native footprint as well as the distance from the center of the tunnel aperture to the center of the footprint was measured.

RESULTS

The AM technique placed 97.7% ± 5% of the tunnel within the native femoral footprint, significantly more than 61.2% ± 24% for the TT technique (P = .001). The AM technique placed the center of the femoral tunnel 3.6 ± 1.2 mm from the center of the native footprint, significantly closer than 6.0 ± 1.9 mm for the TT technique (P = .003).

CONCLUSION

This study demonstrates that use of an accessory medial portal will facilitate more accurate placement of the femoral tunnel in the native ACL femoral footprint.

CLINICAL RELEVANCE

More accurate placement of the femoral tunnel in the native ACL femoral footprint should improve the ability to achieve more anatomic positioning of the ACL graft.

Clinical comparisons between the transtibial technique and the far anteromedial portal technique for posterolateral femoral tunnel drilling in anatomic double-bundle anterior cruciate ligament reconstruction

PURPOSE

The purpose of this study was to compare the clinical results of the transtibial and far anteromedial portal techniques for posterolateral (PL) femoral tunnel drilling in double-bundle anterior cruciate ligament reconstruction.

METHODS

This study involved 50 patients who underwent double-bundle anterior cruciate ligament reconstruction and were followed up for more than 2 years. The anteromedial bundle was reconstructed with the far anteromedial portal technique in all patients. However, the PL bundle was reconstructed with the transtibial and far anteromedial portal techniques in 22 patients (group T) and 28 patients (group F), respectively. The follow-up visits included evaluation of Lysholm knee scores, KT-2000 measurement of anterior knee laxity (MEDmetric, San Diego, CA), the pivot-shift test, and radiography.

RESULTS

The length of the PL femoral tunnel in group F (32.2 mm) was significantly shorter than that in group T (39.0 mm). Lateral knee radiographs showed that the positions of the EndoButtons (Smith & Nephew Endoscopy, Andover, MA) for the PL bundles were significantly more posterior (12.8 mm) and distal (3.1 mm) in group F than in group T. The mean KT-2000 side-to-side difference in group T (0.9 mm) and group F (0.7 mm) did not significantly differ. In addition, no significant difference was noted between the groups with respect to Lysholm knee scores and the pivot-shift test results.

CONCLUSIONS

This study showed that the far anteromedial portal technique is as effective as the transtibial technique and results in good restoration of joint stability and knee scores despite shorter femoral tunnel length and inferoposterior position of the EndoButton.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

Accidental perforation of the lateral femoral cortex in ACL reconstruction: an investigation of mechanical properties of different fixation techniques

PURPOSE

The aim of this study was to evaluate the mechanical properties of anterior cruciate ligament (ACL) reconstruction using the medial portal technique with cortical fixation and hybrid fixation after penetration of the lateral cortex by use of different drill sizes.

METHODS

In this biomechanical study a porcine in vitro model was used. The testing protocol consisted of a cyclic loading protocol (1,000 cycles, 50 and 250 N) and subsequent ultimate failure testing. Number of cyclic loadings survived, stiffness, yield load, maximum load, and graft elongation, as well as failure mode, were analyzed after ACL reconstruction with 5- to 9-mm soft-tissue grafts. In the control group, conventional penetration of the lateral cortex with a 4.5-mm drill and cortical fixation were performed. In the tested groups, the lateral cortex was penetrated with a drill matching the graft size. In the first part of the study, we used cortical fixation. In the second part, we used hybrid fixation with an interference screw.

RESULTS

In the first part of the study, ACL reconstruction with 5- to 6-mm perforation of the lateral cortex showed no significant differences in ultimate failure load after cyclic loading compared with the control group (P > .05). Specimens with reconstruction with 7- to 9-mm perforation of the lateral cortex and cortical fixation did not survive the cyclic loading protocol. In the second part of the study, with a hybrid fixation technique, ultimate failure testing after cyclic loading of specimens with 7- to 9-mm penetration showed no significant differences in tested parameters compared with the control group (P > .05).

CONCLUSIONS

After penetration of the lateral cortex with a drill size of more than 6 mm, cortical ACL fixation results in poor mechanical properties. Hybrid fixation increases the mechanical properties significantly after penetration with a 7- to 9-mm drill.

CLINICAL RELEVANCE

We advise caution to avoid penetration of the lateral femoral cortex when using cortical flip-button fixation. In case of accidental perforation of the lateral cortex with a diameter greater than 6 mm, we recommend performing hybrid fixation.

The effect of graft fixation angles on anteroposterior and rotational knee laxity in double-bundle anterior cruciate ligament reconstruction: evaluation using computerized navigation

BACKGROUND

One of the main differences affecting outcome between single-bundle and double-bundle anterior cruciate ligament (ACL) reconstructions may be graft fixation angles and initial force settings; however, there has been little research to investigate these effects in either technique.

HYPOTHESIS

Anteroposterior and rotational knee laxities will be less in double-bundle ACL reconstructions than single-bundle reconstructions, and different graft fixation angles affect knee kinematics and pivot-shift phenomenon in double-bundle ACL reconstructions.

STUDY DESIGN

Controlled laboratory study.

METHODS

Eleven patients who underwent double-bundle ACL reconstruction were included in this study. The anteromedial bundle (AMB) and the posterolateral bundle (PLB) were provisionally fixed to a graft tensioning system during surgery. The graft fixation settings were as follows: (1) AMB only at 20° (A20), (2) PLB only at 20° (P20), (3) AMB at 20° and PLB at 0° (A20P0), (4) AMB at 20° and PLB at 20° (A20P20), and (5) AMB at 20° and PLB at 45° (A20P45). All the grafts were tensioned at a constant stress level. Anterior tibial translation (ATT), internal rotation (IR), and external rotation (ER) at 30° and 90° of knee flexion applied with manual maximum load were measured before graft insertion and in each setting using a navigation system. A pivot-shift test was also evaluated manually with modified International Knee Documentation Committee criteria in each setting.

RESULTS

A20 was less constrained than A20P20 and A20P45 in ATT at 30° and less constrained than A20P45 in IR at 30°. P20 was less constrained than any other settings in ATT at 30° and less constrained than A20P45 in IR at 30°. A20P0 was less constrained than A20P45 in IR at 30° and in ER at 30°. Grade 1 pivot-shift phenomenon persisted in 8 cases in P20, in 4 cases in A20, and in 3 cases in A20P0, whereas no case showed a positive pivot-shift result in A20P20 and A20P45.

CONCLUSION

In this in vivo laboratory model, double-bundle ACL reconstruction with fixation of AMB at 20° and PLB at 20° or 45° restored better stability than single AMB or single PLB reconstruction in which the graft was of smaller size.

CLINICAL RELEVANCE

In double-bundle ACL reconstruction, fixation of the PLB at 0° might be looser and function worse compared with that of PLB at 20° or 45° when the AMB is fixed at 20°, with the individual variability that should lead to caution until it can be better assessed by surgeons.

Embossing of a screw thread and TCP granules enhances the fixation strength of compressed ACL grafts with interference screws

PURPOSE

Fixation of soft tissue grafts with interference screws relies on the friction of the graft between the screw and the bone tunnel. The goal of this study was to precondition such grafts by mechanical compression in order to reduce anticipated and undesired viscoelastic adaptation of the graft to screw pressure. Further, the otherwise slippery graft surface was modified with impressed tricalcium phosphate granules (TCP) to improve friction and mechanical hold.

METHODS

Fresh flexor digitorum tendons from young bovines were used to create bundles with a diameter of 8-9 mm and were divided into 10 groups to compare the pullout strength and bone damage in a variety of construct scenarios. Specifically, the effects of graft precompression to reduce preimplantation graft diameter were investigated. Further the effects of impressing TCP granules and/or a screw thread into the tendon surface during the compression process were studied.

RESULTS

In sawbone tests, radial graft compression allowed for a smaller bone tunnel (7 mm), but resulted in a significantly lower pullout strength of 174 N (95% CI: 97, 250), compared with controls [315 N (204, 426)]. In contrast, TCP coated [402 N (243, 561)], screw embossed grafts [458 N (302, 614)], and the combination of TCP and embossing [409 N (274, 543)] achieved higher pullout strengths when compared to the standard technique. In porcine bone, untreated grafts using an 8 mm screw pulled out at 694 ± 93 N, significantly higher loads were required to pullout compressed grafts with or without TCP coating (870 ± 74 and 878 ± 131 N), yet fixed with a 7 mm screw.

CONCLUSION

Modification of the tendon graft surface has a large influence on the biomechanical performance of interference screw fixation and results in less bone damage inflicted during insertion to a smaller tunnel diameter, while simultaneously achieving superior pullout strength.

COMPARATIVE STUDY OF ACL RECONSTRUCTION WITH ANATOMICAL POSITIONING OF THE TUNNELS USING THE PATELLAR TENDON VERSUS HAMSTRING TENDON

Objective: To compare ACL reconstruction with anatomical positioning of the tunnels using the hamstring or patellar tendons. Methods: We prospectively evaluated 52 patients who underwent ACL reconstruction using the Chambat's technique, with anatomical positioning of the tunnels drilled outside in. They were divided into group A, with 27 patients, using the patellar tendon as a graft, and group B, with 25 patients, using the hamstring. Results: In group A 26 patients were very satisfied or satisfied and 1 unhappy, in group B. 25 patients were very satisfied or satisfied with the procedure (p = 0.990). According to the Lysholm scale, group A had a mean score of 96.11 and group B, 95.32 (p=0.594). In relation to preoperative IKDC, 100% of the patients in group A and 92% of those in group B were IKDC C or D (p = 0.221); in the assessment with a minimum of two-year follow-up, 96% of group A and 92% of group B were IKDC A or B (p = 0.256). The Lachman test, pivot shift, return to sports activities, and the comparative difference in anterior translation (Rolimeter^TM) also showed no statistically significant difference. In group A, 5 patients (18.5%) were unable to kneel on a hard surface, whereas no patient in group B had this complaint. Conclusion: The anterior cruciate ligament reconstruction presents similar results using the hamstring or patellar tendon with anatomical positioning of the tunnels. Drilling the femoral tunnel outside in is a reproducible and accurate option in the correct placement the femoral tunnel.

Visualization of postoperative anterior cruciate ligament reconstruction bone tunnels: reliability of standard radiographs, CT scans, and 3D virtual reality images

BACKGROUND AND PURPOSE

Non-anatomic bone tunnel placement is the most common cause of a failed ACL reconstruction. Accurate and reproducible methods to visualize and document bone tunnel placement are therefore important. We evaluated the reliability of standard radiographs, CT scans, and a 3-dimensional (3D) virtual reality (VR) approach in visualizing and measuring ACL reconstruction bone tunnel placement.

METHODS

50 consecutive patients who underwent single-bundle ACL reconstructions were evaluated postoperatively by standard radiographs, CT scans, and 3D VR images. Tibial and femoral tunnel positions were measured by 2 observers using the traditional methods of Amis, Aglietti, Hoser, Stäubli, and the method of Benereau for the VR approach.

RESULTS

The tunnel was visualized in 50-82% of the standard radiographs and in 100% of the CT scans and 3D VR images. Using the intraclass correlation coefficient (ICC), the inter- and intraobserver agreement was between 0.39 and 0.83 for the standard femoral and tibial radiographs. CT scans showed an ICC range of 0.49-0.76 for the inter- and intraobserver agreement. The agreement in 3D VR was almost perfect, with an ICC of 0.83 for the femur and 0.95 for the tibia.

INTERPRETATION

CT scans and 3D VR images are more reliable in assessing postoperative bone tunnel placement following ACL reconstruction than standard radiographs.

Tibial rotation under combined in vivo loading after single- and double-bundle anterior cruciate ligament reconstruction

PURPOSE

To evaluate in vivo the differences in tibial rotation between single- and double-bundle anterior cruciate ligament (ACL)-reconstructed knees under combined loading conditions.

METHODS

An 8-camera optoelectronic system and a force plate were used to collect kinematic and kinetic data from 14 patients with double-bundle ACL reconstruction, 14 patients with single-bundle reconstruction, 12 ACL-deficient subjects, and 12 healthy control individuals while performing 2 tasks. The first included walking, 60° pivoting, and stair ascending, and the second included stair descending, 60° pivoting, and walking. The 2 variables evaluated were the maximum range of internal-external tibial rotation and the maximum knee rotational moment.

RESULTS

Tibial rotation angles were not significantly different across the 4 groups (P = .331 and P = .851, respectively) or when side-to-side differences were compared within groups (P = .216 and P = .371, respectively) for the ascending and descending maneuvers, nor were rotational moments among the 4 groups (P = .418 and P = .290, respectively). Similarly, for the descending maneuver, the rotational moments were not significantly different between sides (P = .192). However, for the ascending maneuver, rotational moments of the affected sides were significantly lower by 20.5% and 18.7% compared with their intact counterparts in the single-bundle (P = .015) and double-bundle (P = .05) groups, respectively.

CONCLUSIONS

High-intensity activities combining stair ascending or descending with pivoting produce similar tibial rotation in single- and double-bundle ACL-reconstructed patients. During such maneuvers, the reconstructed knee may be subjected to significantly lower rotational loads compared with the intact knee.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

Effect of malpositioned anterior cruciate ligament replacement on knee joint structures: a biomechanical model

Any sort of malpositioning of anterior cruciate ligament (ACL) replacement leads to an overload of single fibers of the ACL replacement. As long as this does not result in a tear of these fibers so that isometry of the ACL replacement is restored, the abnormal forces acting in and on the ACL replacement are transmitted from the ACL replacement to the remainder of the knee joint structures. We assumed that the posterior cruciate ligament (PCL) is notably affected. The present biomechanical model illustrates the relevant force vectors and reveals the extent of the effect of malpositioned ACL replacement on knee joint structures, particularly the PCL. Further investigations are needed to find out if the presumably occurring overload of a malpositioned ACL replacement can be calculated from its position on an individual basis. This may help deduce recommendations for ACL replacement procedures in the future.

[Medical appraisal of anterior cruciate ligament ruptures]

BACKGROUND

Anterior cruciate ligament tears are one of the most common human ligament ruptures. The assessment of such ruptures is particularly difficult because most ACL injuries involve minimal to no contact. The steps of the assessment are presented with the necessary requirements.

METHOD

Criteria for determining the cause of anterior cruciate ligament ruptures are discussed against the background of our experience and the literature. Different definitions of causality apply to German statutory accident insurance (workers' compensation) on the one hand and to private accident insurance on the other.

RESULTS

The assessment of disability within the scope of workers' compensation in most cases results in "under 10 to 30%", while in private accident insurance it is rated as 1/10 to 1/20 degree of disablement.

Validation of a new technique to determine midbundle femoral tunnel position in anterior cruciate ligament reconstruction using 3-dimensional computed tomography analysis

PURPOSE

The purpose of this study was to investigate and report on a new intraoperative measuring technique to place the anterior cruciate ligament (ACL) femoral tunnel in the center of the native ACL femoral insertion site.

METHODS

We investigated a novel measuring technique based on identifying the proximal border of the articular cartilage and using a specific ruler parallel to the femoral axis to locate the origin of the ACL. The accuracy of this technique was validated by measuring tunnel position on postoperative 3-dimensional computed tomography scans. Bony tunnels created by the ruler technique were compared with tunnels drilled by a traditional technique referenced from the back wall of the notch.

RESULTS

Fifty ACL reconstructions were performed by the novel measuring technique, with placement of the femoral tunnel at the center of the femoral insertion. The mean position for the center of the femoral tunnel measured by the ruler technique was 0.9 mm from the theoretic optimal center position but was a very distinct 5 mm from the mean position in the traditional tunnels.

CONCLUSIONS

The ruler technique produced femoral tunnels comparable to published radiographic criteria used for tunnel placement and is reproducible and accurate. We recommend placement of the femoral tunnel at the midpoint of the lateral femoral condyle when using the anatomic single-bundle technique.

LEVEL OF EVIDENCE

Level IV, case series.

Anatomic double-bundle anterior cruciate ligament reconstruction using bone-patellar tendon-bone and gracilis tendon graft: a comparative study with 2-year follow-up results of semitendinosus tendon grafts alone or semitendinosus-gracilis tendon grafts

PURPOSE

The purpose of this study was to assess the clinical results of anatomic double-bundle anterior cruciate ligament (ACL) reconstruction by use of bone-patellar tendon-bone and gracilis tendon (BPTB-G) grafts and to compare them with the results of double-bundle ACL reconstruction by use of semitendinosus tendon (ST) or semitendinosus-gracilis tendon (ST-G) grafts, with particular emphasis on the postoperative incidence of anterior knee pain.

METHODS

The study comprised 144 patients who underwent unilateral anatomic double-bundle ACL reconstruction with 3 graft types, including 55 BPTB-G, 56 ST, and 33 ST-G grafts. A traumatic graft rupture occurred within 2 years postoperatively in 5 patients (1 BPTB-G, 3 ST, and 1 ST-G). Clinical results and incidence and severity of anterior knee pain were assessed and compared among the 3 different graft groups at 2 years postoperatively. Potential variables influencing postoperative anterior knee pain development were subjected to univariate analysis, followed by logistic regression analysis to identify risk factors for anterior knee pain.

RESULTS

Both subjective and objective clinical results in anatomic double-bundle ACL reconstruction with BPTB-G graft were similar to those using ST or ST-G graft at 2 years postoperatively. The incidences of anterior knee pain at 2 years' follow-up were 18.5%, 9.4%, and 9.3% in the BPTB-G, ST, and ST-G groups, respectively, indicating no statistically significant difference among the 3 groups. Multivariate logistic regression analyses showed that BPTB graft harvest and patellofemoral cartilage defect failed to be significant factors for anterior knee pain whereas quadriceps peak torque at 60°/s was the only significant factor for anterior knee pain at 2 years.

CONCLUSIONS

Clinical results including the incidence of anterior knee pain 2 years after anatomic double-bundle ACL reconstruction with BPTB-G grafts were comparable to those after ACL reconstruction with ST or ST-G grafts.

LEVEL OF EVIDENCE

Level III, therapeutic, retrospective comparative study.

Structural properties of a new fixation strategy in double bundle ACL reconstruction: the MiniShim

INTRODUCTION

Double-bundle reconstruction of the ACL has become the focus of scientific and clinical interest in the last years. However, there is still a discussion about the most appropriate technique for graft fixation. Both, extracortical fixation systems like the Endobutton and aperture fixation by interference screws have advantages as well as disadvantages. Aim of this study was to analyze the biomechanical properties of a new small wedge shaped implant (MiniShim, Karl Storz, Germany) for the fixation of a soft tissue graft in double bundle ACL reconstruction and to compare it to an aperture fixation by interference screw and an extracortical fixation.

METHODS

Porcine knees and flexor tendons were used for this study. 5 and 6 mm tunnels were drilled. The following fixation strategies were tested: 4 and 5 mm MiniShim (Karl Storz Germany), 6 mm interference screw (MegaFix, Karl Storz, Germany), hybridfixation by FlippTack (FlippTack, Karl Storz, Germany) and MiniShim and hybridfixation by FlippTack and 6 mm interference screw. All fixation strategies were tested with a 5 and 6 mm tendon graft. Maximum load, yield load and stiffness were recorded using a material testing machine. Load was applied in line with the bone tunnel. Grafts were cyclically preconditioned between 0 and 20 N for 10 cycles before the graft-bone-complex was loaded to failure. Statistical evaluation was performed using SPSS Version 11.0.

RESULTS

Load to failure for the 5 mm graft was 81.1 and 118.0 N for the 4 and 5 mm MiniShims. Fixation by interference screw reached 237.4 N. The extracortical fixation resulted in a load to failure of 471.7 N. Load to failure for the 6 mm tendon grafts was 52.0 and 92.8 N for the 4 and 5 mm MiniShims. Fixation by interference screw resulted in a load to failure of 214.0 N. Extracortical fixation failed at 451.7 N. The difference between MiniShim and interference screw was statistically significant. Load to failure was significantly higher for extracortical fixation compared to fixation by MiniShim or interference screw. Hybrid fixation showed higher fixation strength compared to fixation by interference screw or MiniShim alone. This difference was statistically significant. Stiffness was significantly higher for fixation by interference screw compared to extracortical fixation and fixation by MiniShim. Four different modes of failure could be seen. All 4 mm MiniShims failed by slippage of the tendon past the MiniShim. In the 5 mm group the fixation failed by pullout of the MiniShim or the tendon past the MiniShim. Hybrid fixation failed by rupture of the linkage material. When the graft was fixed by an interference screw failure occurred by rupture of the tendon at the fixation side.

CONCLUSION

Hybrid fixation using the MiniShim provides biomechanical properties strong enough to withstand the forces occurring during rehabilitation and comparable to the fixation strength provided by interference screw. While fixation by MiniShim alone does not provide sufficient fixation strength in double bundle ACL reconstruction, hybridfixation using a cortical fixation by FlippTack is an alternative to aperture fixation by interference screw concerning primary stability.

Anatomical single bundle anterior cruciate ligament reconstruction

We present a review of the literature looking at the anatomy of the Anterior Cruciate Ligament, the biomechanical aspects of ACL reconstruction, review the outcomes of single and double bundle ACL reconstruction and present the current techniques for anatomic single bundle reconstruction.

All-inside anterior cruciate ligament graft-link technique: second-generation, no-incision anterior cruciate ligament reconstruction

We describe an anatomic, single-bundle, all-inside anterior cruciate ligament (ACL) graft-link technique using second-generation Flipcutter guide pins (Arthrex, Naples, FL), which become retrograde drills, and second-generation cortical suspensory fixation devices with adjustable graft loop length: femoral TightRope (Arthrex) and tibial ACL TightRope-Reverse Tension (Arthrex). The technique is minimally invasive using only four 4-mm stab incisions. Graft choice is no-incision allograft or gracilis-sparing, posteriorly harvested semitendinosus material. The graft is sutured 4 times through each strand in a loop and linked, like a chain, to femoral and tibial adjustable TightRope graft loops. With this method, graft tension can be increased even after graft fixation. The technique may be modified for double-bundle ACL reconstruction.

Radiographic landmarks for tunnel positioning in double-bundle ACL reconstructions

PURPOSE

The purpose of this study was to establish quantitative and qualitative radiographic landmarks for identifying the femoral and tibial attachment sites of the AM and PL bundles of the native ACL and to assess the reproducibility of identification of these landmarks using intraclass correlation coefficients. It was hypothesized that the radiographic positions of the AM and PL bundles could be defined in relation to anatomic landmarks and radiographic reference lines.

METHODS

The femoral and tibial attachment sites of the AM and PL bundles on twelve cadaveric knees were labeled with radio-opaque markers. The positions of the AM and PL bundle attachment sites were quantified on radiographs by three independent examiners.

RESULTS

On the lateral femoral view, the AM bundle was located at 21.6 ± 5.6% of the sagittal diameter of the femur drawn along Blumensaat's line and 14.2 ± 7.7% distal to the notch roof along the maximum notch height. The PL bundle was located at 28.9 ± 4.6% of the sagittal diameter and 42.3 ± 6.0% of the notch height. The knee flexion angle at which the AM and PL bundle attachment sites were horizontally oriented was 115 ± 7.1°. On the tibial AP view, the AM and PL bundles were located at 44.2 ± 3.4 and 50.1 ± 2.1%, respectively, from the medial aspect of the tibia along its coronal diameter. On the lateral view, the distances from the AM and PL bundles to the anterior tibial margin measured along the tibial sagittal diameter were 36.3 ± 3.8 and 51.0 ± 4.0%, respectively. The center of the PL bundle attachment was located almost precisely at the center of the tibial plateau in both the coronal and sagittal planes.

CONCLUSIONS

This study defines the radiographic locations of the femoral and tibial bundle attachment sites of the native ACL and a reliable and transferrable protocol for identifying these sites on radiographs in relation to surrounding landmarks and digitally projected reference lines. In addition, it was found that the femoral attachments of the AM and PL bundles were horizontally aligned at 115° of knee flexion and the PL bundle tibial attachment was located essentially at the center of the tibia.

Avoiding tunnel collisions between fibular collateral ligament and ACL posterolateral bundle reconstruction

PURPOSE

The purpose of this study was to evaluate the risk of tunnel collisions of the fibular collateral ligament (FCL) and posterolateral bundle anterior cruciate ligament (PLB-ACL) tunnels during a combined FCL and double-dundle (DB) ACL reconstruction.

METHODS

Thirty-six 4th-generation synthetic femurs (Sawbones, Pacific Research Laboratories, Vashon, WA) were utilized, and two different femur sizes were used. A FCL tunnel and a PLB-ACL tunnel were reamed on each femur. The tunnels of synthetic specimens that did not have a collision were filled with an epoxy resin augmented with BaSO(4) and radiographic evaluation, and Multidetector CT exams of the specimens were performed.

RESULTS

The rate of tunnel collision when the FCL tunnel was reamed to a depth of 30 mm was 75 and 69.4% for the 25 mm depth. There was a significantly increased risk of tunnel collision when the FCL tunnel was reamed proximally with coronal angulations of 20° and 40°. No collisions were noted when the FCL tunnel was reamed parallel to the distal condylar line and with axial angulations of 20° and 40°.

CONCLUSION

This study provides new insight into tunnel positioning during a combined FCL and DB-ACL reconstruction. The results show that a concomitant FCL injury do not represent a contraindication to perform a DB-ACL reconstruction as long as the FCL tunnel is reamed with no proximal angulation and is directed anteriorly with an axial angulation between 20° and 40°.

Anatomical placement of double femoral tunnels in anterior cruciate ligament reconstruction: anteromedial tunnel first or posterolateral tunnel first?

PURPOSE

The purpose of this study was to know which tunnel--the anteromedial (AM) bundle or the posterolateral (PL) bundle--should be prepared first to create the 2 femoral tunnels accurately in anatomic double-bundle (DB) anterior cruciate ligament (ACL) reconstruction.

METHODS

Thirty-four patients were divided into 2 groups of 17 depending on the sequence of preparation of the 2 femoral tunnels. In group A, the AM tunnel was prepared first, whereas the PL tunnel was prepared first in group P. ACL reconstruction was performed using a three-dimensional (3-D) fluoroscopy-based navigation system to place the double femoral tunnels through an accessory medial portal. The double femoral socket positioning was evaluated by 3-D computed tomography (CT) scan image.

RESULTS

The non-anatomical placement of the femoral sockets occurred in 5 patients (29%) in group A, whereas the 2 sockets were placed anatomically in all patients in group P (P < 0.05). Evaluation of the AM and the PL socket location on the 3-D CT images using the quadrant method showed more similar values to the laboratory data in a literature in group P than in group A. No complication occurred in group A, whereas complications such as socket communications or back wall blowout occurred in 5 patients (29%) in group P (P < 0.05).

CONCLUSION

The sequence of creating 2 femoral tunnels through accessory medial portal affected the resultant location of the sockets and the rate of the complications. When femoral tunnels are prepared with a transportal technique, PL tunnel first technique seems to be superior to AM first technique regarding anatomic placement. However, PL tunnel first technique accompanies the risk of socket communication.

ACL injury and surgical treatment options

The anterior cruciate ligament (ACL) has been the focus of a substantial amount of research. Thousands of studies have evaluated the structure and function of the intact ACL, as well as the best reconstruction techniques. Despite the amount of literature, many controversies remain regarding the ACL and its surgical reconstruction. This article reviews the anatomy and function of the native ACL, the nature of injury, and aspects of ACL reconstruction, including surgical approach, tunnel positioning, graft choice, and graft fixation.

Use of the 70° arthroscope for improved visualization with common arthroscopic procedures

The vast majority of common arthroscopic procedures are performed with a 30° arthroscope for visualization. Although the 70° arthroscope has been described for a myriad of applications, its utility has recently been forgotten. We have explored the use of the 70° arthroscope for a myriad of arthroscopic procedures and identified a number of circumstances in which it offers superior visualization to a 30° arthroscope. These procedures include arthroscopic shoulder stabilization, distal clavicle resection, acromioclavicular joint reconstruction, rotator cuff repair, elbow arthroscopy, anterior cruciate ligament reconstruction, posterior cruciate ligament reconstruction, arthroscopy of the posterior knee compartments, hip arthroscopy, and subdeltoid shoulder arthroscopy.

MRI analysis of tibial position of the anterior cruciate ligament

This study aimed to establish normal values for the position of the native anterior cruciate ligament (ACL) insertion on the tibia to assist in the evaluation of tunnel placement after primary ACL reconstruction or prior to revision surgery. One hundred consecutive MRI studies performed on patients with a mean age of 29 years (range 20-35) from a single MRI facility were reviewed. Patients with prior surgery, significant osteoarthritis, acute ACL injury, or evidence of ACL reconstruction were excluded. Using digital image software, measurements were taken of anterior-most and posterior-most portions of the ACL insertion on the tibia. Depth of the tibia was also measured from the anterior edge of the tibial plateau to the posterior edge at the origin of the posterior cruciate ligament. The anterior insertion of the native ACL was located at a mean of 14 ± 3 mm (28 ± 5%) from the anterior tibial articular margin; the posterior portion of the ACL was located at a mean of 31 ± 4 mm (63 ± 6%). The tibial insertion of the ACL is located between 28 and 63% of the total anterior-posterior depth of the tibia. The results from this study are clinically relevant as they provide the clinician with baseline data to describe the position of the tibial footprint of the native ACL on sagittal MR imaging. Further, this data can be used as a guide to evaluate tibial tunnel position prior to primary ACL reconstruction, revision ACL surgery, or in ACL-reconstructed patients who continue to experience pain, instability, or dysfunction postoperatively.