Objectives

Our aim was to assess the use of intra-operative fluoroscopy in the assessment of the position of the tibial tunnel during reconstruction of the anterior cruciate ligament (ACL).

Previous research has shown that tunnel placement is critical in ACL reconstruction. The ultimate position of both the femoral and tibial tunnel determines knee kinematics and overall function of the knee post surgery. As with all techniques there is a definite learning curve for the arthroscopic technique. However, the effect of the learning curve on tunnel placement has been studied sparsely. The purpose of this project therefore is to investigate the effect of the learning curve on tunnel placement. Postoperative radiographs of the first 200 anterior cruciate reconstructions with bone-tendon-bone patella tendon of a single orthopaedic surgeon performed during the first four years of independent practice were analysed for tunnel placement. Radiographs were digitalised and imported into a CAD program. Tunnel placement both femoral and tibial antero-posterior and sagittal was assessed using Sommer's criteria. A rating scale was developed to assess overall placement. A total of 100 points indicated perfect placement. A maximum of 30 points each were allocated for sagittal femoral and tibial placement and a maximum of 20 points each were allocated for coronal placement. Tunnel placement scores improved from 66 for the first 25 procedures to 87 for the last 25 procedures. Sagittal femoral placement (zone 1–4 with zone 1 being the preferred zone of placement) improved from an average of 1.44 to 1.08. Sagittal tibial placement (45% from anterior border of tibia) did not change significantly and remained between 42.82 t0 44.76%. Coronal femoral placement (between 10:00–11:00 o'clock for the right knee and 1:00–2:00 for the left knee) ranged from 10.45–11.15 and 12:45-1:15 o'clock respectively. This finding may be related to the transtibial tibial technique used to place the femoral tunnel. Coronal tibial placement (45% from medial tibial border) ranged from 45-46.58%. Correct placement of the femoral and tibial bone tunnels is important for a successful reconstruction of the anterior cruciate ligament (ACL). This study demonstrated a definitive learning curve and steady improvement of tunnel placement. Whilst there was no significant improvement in sagittal placement, overall placement improved significantly

There is increasing interest in the placement of the femoral and tibial tunnels for anterior cruciate ligament (ACL) reconstruction, with a trend towards a more anatomically accurate reconstruction. Non-anatomical reconstruction of the ACL has been suggested to be one of the major causes of osteoarthritis in the knee following ACL rupture. Knee surgeons from an international community were invited to demonstrate their method for arthroscopic ACL tunnel placement in an ACL deficient cadaveric knee. These positions were recorded with image intensification and compared with the native ACL insertion sites, which had previously been recorded with image intensification, before the ACL had been resected. Some clear trends were observed; the use of three tunnel placement techniques (anatomic ridges, ‘ruler method’ and use of image intensification) was associated with most accurate position of the femoral tunnel in the centre of the native ACL femoral insertion site. The choice of arthroscopy portals also affected tunnel placement. There is considerable variation in ACL reconstruction tunnel placement amongst experienced knee surgeons. This study provides useful information as to which tunnel placement methods are associated with the most anatomically accurate ACL reconstruction

Introduction. An accurate and reproducible tibial tunnel placement without danger for the posterior neurovascular structures is a crucial condition for successful arthroscopic reconstruction of the posterior cruciate ligament (PCL). This step is commonly performed under fluoroscopic control. Hypothesis: Performing the tibial tunnel under exclusive arthroscopic control leads to accurate tunnel placement according to recommendations in the literature. Materials and Methods. Between February 2007 and December 2009, 108 arthroscopic single bundle PCL reconstructions in tibial tunnel technique were performed. The routine postoperative radiographs were screened according to defined quality criterions: 1. Overlap of the medial third of the fibular head by the tibial metaphysis on a-p views 2. Overlap of the dorsal femoral condyles within a range of 4 mm on lateral views 3. X-ray beam parallel to tibial plateau in both views. The radiographs of 48 patients (48 knees) were enrolled in the study. 10 patients had simultaneous ACL reconstruction and 7 had PCL revision surgery. The tibial tunnel was placed under direct arthroscopic control through a posteromedial portal using a standard tibial aming device. Key anatomical landmarks were the exposed tibial insertion of the PCL and the posterior horn of the medial meniscus. During digital analysis of the postoperative radiographes, the centre of the posterior tibial outlet was determined. On the a-p view, the horizontal distance of this point to the medial tibial spine was measured. The distance to the medial border of the tibial plateau was related to its total width. On the lateral view the vertical tunnel position was measured perpendicularly to a tangent of the medial tibial plateau. Results. The mean mediolateral tunnel position was 49,3 ± 4,6%, 6,7 ± 3,6 mm lateral to the medial tibial spine. On the lateral view the tunnel centre was 10,1 ± 4,5 mm distal to the bony surface of the medial tibial plateau. Neurovascular damage was observed in none of our patients. Conclusion. The results of this radiological study confirm that exclusive arthroscopic control for tibial tunnel placement in PCL reconstruction yields reproducible and accurate results according to the literature. Our technique avoids radiation, facilitates the operation room setting and enables the surgeon to visualize the key landmarks for tibial tunnel placement

Introduction. Anatomical reconstruction of the Anterior Cruciate Ligament (ACL) reconstruction has been shown to improve patient outcome. The posterior border of the anterior horn of the lateral meniscus (AHLM) is an easily identifiable landmark on MRI and arthroscopy, which could help plan tibial tunnel position in the sagittal plane and provide anatomical graft position intra-operatively. Method. Our method for anatomical tibial tunnel placement is to establish the relation of the posterior border of AHLM to the centre of the ACL footprint on a pre-operative sagittal MRI. Based on this relationship studied on preoperative MRI scan, posterior border of AHLM is used as an intra- operative arthroscopic landmark for anatomic tibial tunnel placement during ACL reconstruction. This relationship has been studied on 100 MRI scans where there was no ACL or LM injury (Bone and Joint Journal 2013 vol 95-B, SUPP 19). The aim of the study is to validate our method for anatomical tibial tunnel placement. Results. 25 patients with ACLR where there were both pre and post op MRI scan with good quality images of AHLM and tibial tunnel opening were included in this study. The preoperative relationship between posterior border of AHLM and centre of ACL footprint was compared with that between the posterior border of AHLM and centre of tibial tunnel on postop MRI scans. The measurements were done by two observers on two different occasions to establish intra and inter observer correlation. Discussion and Conclusion. There was significant correlation between pre-op (0.4mm) and post-op (0.4mm) distances between the AHLM and the centre of the ACL footprint/graft. There was significant inter-observer correlation (paired T-test =0.89, p<0.05) in pre- and post-op measurements. No significant difference was found in the difference between the means in pre-op and post-op MRI scans between observers (p=0.79). These results suggest that the AHLM is a reliable and valid intra-operative marker for anatomic ACL tibial tunnel placement

Correct femoral tunnel position in anterior cruciate ligament reconstruction (ACLR) is critical in obtaining good clinical outcomes. We aimed to delineate whether any difference exists between the anteromedial (AM) and trans-tibial (TT) portal femoral tunnel placement techniques on the primary outcome of ACLR graft rupture. Adult patients (>18year old) who underwent primary ACLR between January 2011 – January 2018 were identified and divided based on portal technique (AM v TT). The primary outcome measure was graft rupture. Univariate analysis was used to delineate association between independent variables and outcome. Binary logistic regression was utilised to delineate odds ratios of significant variables. 473 patients were analysed. Median age at surgery was 27 years old (range 18–70). A total of 152/473, (32.1%) patients were AM group compared to 321/473 (67.9%) TT. Twenty-five patients (25/473, 5.3%) sustained graft rupture. Median time to graft rupture was 12 months (IQR 9). A higher odds for graft rupture was associated with the AM group, which trended towards significance (OR 2.03; 95% CI 0.90 – 4.56, p=0.081). Older age at time of surgery was associated with a lower odds of rupture (OR 0.92, 95% CI 0.86 – 0.98, p=0.014). There is no statistically significant difference in ACLR graft rupture rates when comparing anteromedial and trans-tibial portal technique for femoral tunnel placement. There was a trend towards higher rupture rates in the anteromedial portal group

Background: As many as 175,000 anterior cruciate ligament (ACL) reconstructions are performed annually in the United States at a cost > 1 billion dollars. Estimates of the rate of revision surgery are as high as 10%–20%, potentially resulting in as many as 35,000 revisions a year. In addition, errors that are not obvious at short-term or mid-term follow-up may have significant long--term effects in young patients. Studies have demonstrated that the majority of visions are related to technical errors, primarily tunnel placement. Computer-aided navigation systems provide enhanced precision in tunnel placement and may reduce the rate of revision surgery. Computer-aided systems can provide valuable data on rotational and translational laxity of the knee. Aim: To assess the accuracy of tibial and femoral tunnel placement comparing the Acuflex and Arthrex guides with navigated technique. Methods: Five formalin preserved cadavers were divided into two groups. An experienced Surgeon comfortable with the jigs and the navigation technique performed all the reconstructions. Group A knees had ACL reconstructions using the Arthrex guide (4 knees) and Group B using the computer navigated technique (5 knees). Quadrupled Hamstring tendon grafts were used for reconstruction. All 9 knees were examined following ligament reconstruction with plain radiography and CT scans to assess the accuracy of the tunnel placement. Computer navigation was performed using the Brain Lab software. Implants used for fixation were Ezlock (Arthrotek, UK) for the femur and interference screw for the tibia. Results: The findings suggest variability of accuracy in tunnels placement using the two techniques. ACL reconstruction should be carried out with accurate tunnel placement. Care should be taken in placing the tunnel as errors will lead to failure of the reconstructed ligament. Computer aided navigation is recommended in performing ACL reconstructions

Abstract. The radiographic or bony landmark techniques are the two most common methods to determine Medial patellofemoral ligament (MPFL) femoral tunnel placement. Their intra/inter-observer reliability is widely debated. The palpation technique relies on identifying the medial epicondyle (ME) and adductor Tubercle (AT). The central longitudinal artery and associated vessels (CLV) are consistently seen in the surgical dissection during MPFL reconstruction. The aim of this study was to investigate the anatomic relationship of CLV to ME-AT and thereby use CLV as an important vascular landmark during MPFL reconstruction. A retrospective review of MRI scans in skeletally mature patients presenting to a tertiary referral knee clinic was undertaken. Group-N consisted of any presentation without patellofemoral instability or malalignment (PFI). Group-P with PFI. MRI's were reviewed and measured by two Consultant Radiologists for the CLV-ME-AT anatomy and relationship. Following exclusions 50 patients were identified in each group. The CLV passed anterior to the AT and ME in all patients. ME morphology did not differ greatly between the groups except in the tubercle height, where there was a statically but not clinically significant difference (larger in the non-PFI group, 2.95mm vs 2.52mm, p=0.002). The CLV to ME Tip distance was consistent between the groups (Group PFI group 3.8mm & ‘normal’ non-PFI Group 3.9mm). The CLV-ME-AT relationship remained consistent despite patients presenting pathology. The CLV consistently courses anterior to ME and AT. The CLV could be used as a vascular landmark assisting femoral tunnel placement during MPFL reconstruction

Aim: To study the effect intra-operative image guidance has on the position of both femoral and tibial tunnel placement in primary anterior cruciate ligament reconstruction surgery. Methods: Prospective study of 2 consecutive series of 10 patients undergoing ACL reconstruction surgery all operated on by the same surgeon (the senior author). In the first group intra-operative image guidance in the form of a standard image intensifier was used to guide the surgeon in the positioning of the tibial and femoral tunnels. In the second group no image guidance was used. The position of the femoral and tibial tunnels were assessed on AP and lateral radiographs post operatively and recorded. The two groups were compared. Conclusion: There was no significant difference in the position of the femoral tunnel position between the 2 groups (p=0.23). There was no significant difference in the position of the tibial tunnel between the 2 groups, in either the AP (p=0.37) or lateral (p=> 0.5) plane. There appears to be no benefit to using an image intensifier to aid in tunnel preparation in ACL reconstruction surgery

Introduction. Anatomical reconstruction of the Anterior Cruciate Ligament (ACL) reconstruction has been shown to be desirable and improve patient outcome. The posterior border of the anterior horn of the lateral meniscus (AHLM) is an easily identifiable arthroscopic landmark, which could guide anatomic tibial tunnel position in the sagital plane. The aim of the study was to establish the relationship between the posterior border of AHLM and the centre of the ACL foot print to facilitate anatomical tibial tunnel placement. Materials/Methods. We analysed 100 knee MRI scans where there was no ACL or lateral meniscal injury. We measured the distance between the posterior border of the AHLM and the midpoint of the tibial ACL footprint in the sagital plane. The measurements were repeated 2 weeks later for intra-observer reliability. Results. The mean distance between the posterior border of the AHLM and the ACL midpoint was −0.1mm (i.e. 0.1mm posterior to the ACL midpoint). The range was 5mm to −4.6mm. The median value was 0.00mm. 95% confidence interval was from 0.3 mm to −0.5 mm. A normal, parametric distribution was observed and Intra-observer variability showed significant correlation (p=0.01) using Pearsons Correlation test. Conclusion. Using the posterior border of the AHLM is a reliable, reproducible and anatomic marker for the midpoint of the ACL footprint in the majority of cases. It can be used intra-operatively as a guide for tibial tunnel and graft placement allowing anatomical reconstruction. There will inevitably be some anatomical variation. Pre-operative MRI assessment of the relationship between AHLM and ACL footprint is advised to improve surgical planning

The outcome following arthroscopic anterior cruciate (ACL) reconstruction is dependant on a combination of surgical and non-surgical factors. Technical error is the commonest cause for graft failure, with poor tunnel placement accounting for over 80% of those errors. A routine audit of femoral and tibial tunnel positions following single bundle hamstring arthroscopic ACL reconstruction identified apparent inconsistent positioning of the tibial tunnel in the sagittal plane. Intra-operative fluoroscopy was therefore introduced (when available) to verify tibial guide wire position prior to tunnel reaming. This paper reports a comparison of tibial interference screw position measured on post-operative radiographs with known tunnel position as shown on intra-operative fluoroscopic images in 20 patients undergoing routine primary ACL reconstruction between January and June 2009. Surgery took a mean of 5 minutes longer when intra-operative fluoroscopy was used. In 3/20 patients, fluoroscopy led to re-positioning of the tibial guide wire prior to tunnel reaming. The mean tibial tunnel position as indicated by the tunnel reamer was 41 +/− 2.7 % of the total plateau depth (range 37% to 47%). The mean position projected from the tibial screw on post operative radiographs was 46 +/− 9.2% (range 38% to 76%). A paired t-test showed a significant difference (p = 0.022) between true tunnel position and tibial screw position. 6/20 patients had post operative screw positions that were > 5% more posterior than the known position of the tibial tunnel. The position of the tunnel should be measured at its mid-point where this is evident. On most early radiographic images, the margins of the tunnel are not clear and therefore a line projected from the centre of the screw is used. This audit demonstrates the potential inaccuracy associated with this

Purpose. The purpose of this study was to determine whether intra-operative identification of osseous ridge anatomy (lateral intercondylar “residents” ridge and lateral bifurcate ridge) could be used to reliably define and reconstruct individuals' native femoral ACL attachments in both single-bundle (SB) and double-bundle (DB) cases. Methods. Pre-and Post-operative 3D, surface rendered, CT reconstructions of the lateral intercondylar notch were obtained for 15 patients undergoing ACL reconstruction (11 Single bundle, 4 Double-bundle or Isolated bundle augmentations). Morphology of native ACL femoral attachment was defined from ridge anatomy on the pre-operative scans. Centre's of the ACL attachment, AM and PL bundles were recorded using the Bernard grid and Amis' circle methods. During reconstruction soft tissue was carefully removed from the lateral notch wall with RF coblation to preserve and visualise osseous ridge anatomy. For SB reconstructions the femoral tunnel was sited centrally on the lateral bifurcate ridge, equidistant between the lateral intercondylar ridge and posterior cartilage margin. For DB reconstructions tunnels were located either side of the bifurcate ridge, leaving a 2mm bony bridge. Post-operative 3D CTs were obtained within 6 weeks post-op to correlate tunnel positions with pre-op native morphology. Results. Pre-op native ACL attachment site morphology was very similar to previous in-vitro studies: the mean centre was found at 27% along Blumensaat's line (range 19-33%) and 38% the width of the lateral femoral condyle (range 31-43%). Despite the variability between individuals there was close correlation between pre-operative localization of the femoral attachment centre and position of single bundle ACL reconstructions tunnels on the post-op CT (R=0.92). Similar results were observed for double-bundle and isolated bundle augment reconstructions. Conclusion. ACL attachment site morphology varies between individuals. Intra-operative localization of the osseous landmarks (lateral intercondylar and bifurcate ridges) appears to lead to accurate, individualised anatomical tunnel placement whether using single or double-bundle reconstruction techniques

There is significant disagreement among surgeons regarding optimal placement of the femoral tunnel for anterior cruciate ligament reconstruction. Placement of the femoral tunnel via a transtibial approach usually will not allow consistent overlap between the tunnel and the anterior cruciate ligament footprint. This remains true in recent publications in spite of the fact that the tunnel center lay totally outside the femoral footprint.

We have performed radiographic studies (Feller et al, 1993), cadaveric studies (Kaseta et al 2008) and currently postoperative studies showing that femoral tunnel creation is much more anatomic with an independent drilling technique. We have performed postoperative high resolution MRI exams of both knees using a protocol that reliably shows the anterior cruciate ligament footprint on the normal knee and the tunnel on the surgical knees. The centers are approximately 2mm. apart for independent techniques and 9mm. apart of the transtibially created tunnels.

We are now using dual angle fluoroscopy and high resolution MRI mapping to evaluate the in vivo kinematics of knees following anterior cruciate ligament reconstruction with independent or transtibial techniques.

Background

Recent publications have supported the anatomic placement of anterior cruciate grafts to optimise knee function. However, anatomic placement using the anteromedial portal has been shown to have a higher failure rate than traditional graft placement using the transtibial method. This is possibly due to it being more technically difficult and to the short femoral tunnel compromising fixation methods. It also requires the knee to be in hyper flexion. This position is not feasible during with a tourniquet in situ on the heavily muscled thighs of some athletes.

Hypothesis: That navigation can be used to place the femoral tunnel in the anatomic position via a more medial transtibial tunnel.

ACL reconstruction is successful in restoring sagittal stability of the knee but has been less consistent in restoring rotational stability. Increasing coronal graft obliquity improves rotational constraint of the knee in cadaveric biomechanical models. The purpose of this study was to determine whether there is a correlation between coronal graft alignment and tibial rotation during straight line activities.

Seventy-four patients who had undergone ACL reconstruction using a transtibial technique were evaluated. They came from three distinct time periods during which the operating surgeon had deliberately changed the position of the femoral tunnel to progressively achieve a more oblique graft alignment in the coronal plane. Post-operative radiographs were analyzed for the coronal graft orientation and femoral and tibial tunnel positions. Tibial rotation was measured during level walking (n=74) and single-limb landing (n=42) tasks using a motion analysis system. Radiographic measurements of graft and tunnel orientation were correlated with rotational excursion of the knee recorded during these tasks. No correlations were found between knee rotational excursion and either the coronal tibial tunnel angle or the coronal graft angle during level walking. For the single-limb landing task, a significant negative correlation was observed between the coronal angle of the tibial tunnel and rotational excursion (r=−0.3, p=0.05) i.e. increasing tunnel obliquity was associated with decreasing rotational excursion. For the coronal angle of the ACL graft, the correlation was also negative, but was not significant (r=−0.24, p=0.12).

Increases in graft obliquity in the coronal plane were associated with reduced tibial rotational excursions during single limb landing. These findings support the notion that ACL graft orientation may play a role in rotational kinematics of the ACL reconstructed knee, particularly during higher impact activities.

Aim: To evaluate whether a guiding pin for a femoral tunnel could be positioned through the tibial tunnel into the center of the anatomical ACL attachment. Methods: 77 knees underwented arthroscopic ACL reconstruction with hamstrings. The femoral tunnel was drilled through an anteromedial portal at the center of the anatomic insertion at about 10.00 resp.14.00 position. Tibial tunnel (mean diameter 7.55 ± 0.54 mm) was drilled using a guide inserted at 90 degrees of knee flexion. Then, through the tibial tunnel, a 4mm offset femoral drill guide was positioned as close as possible to the femoral tunnel and a 2.5 mm guide wire was drilled. The position of the guide wire was photographed arthroscopically and the deviation was measured as the distance between the center of the femoral tunnel and the guide wire. Results: The mean deviation was 4.50 ± 1.54 mm (p = 0.00000004) In 74 knees (96.1%) the guidewire did not reach the femoral tunnel. Only in 3 knees it reached the superomedial edge of the femoral tunnel. No statistical relationship was found between deviation and tibial tunnel inclination angles or tibial tunnel diameter. Conclusions: Transtibial femoral tunnel drilling does not reach the anatomic site of the ACL insertion, even with larger tibial tunnels (for hamstring grafts up to 8.5 mm). Transtibial tunnel drilling should be replaced by drilling through the anteromedial portal at least for tunnels with diameters < 9 mm.

Anatomic all-inside ACL reconstruction using TransLateral technique is a relatively new technique that reduces surgical invasion and pain leading to early recovery. We evaluated clinical outcomes of patients undergoing primary anatomic all-inside ACL reconstruction using TransLateral technique. Retrospective case-series evaluating patients undergoing surgery from June 2013 – December 2017. Patients were followed up clinically and using PROMS including EQ-5D, KOOS, IKDC and Tegner scores. Paired two-tailed student t-tests were used to assess clinical significance. 138 patients were included (115 males, 23 females). Mean age was 30 years (range 16.0 – 60.2). Graft choice included isolated semitendinosus (n=115) or both semitendinosus and gracilis (n=26). Mean graft length and diameter were 62.1mm and 8.7mm. Sixteen cases (11.3%) returned to theatre; MUA for arthrofibrosis (n=4), infection (n=2), haemarthrosis (n=1) and metalwork failure (n=1). Incidence of graft re-rupture was 5.7% (n=8); 7 cases were in the mid-bundle femoral tunnel placement. 52.5% (n=74) had complete peri-operative PROMS scores. Mean peri-operative EQ-5D VAS scores were 69.8 and 78.2 (p=0.02). Mean peri-operative KOOS scores for all domains demonstrated significant improvements (p<0.001). Mean peri-operative IKDC scores were 46.1 and 72.5 (p<0.05) and peri-operative Tegner activity scores were 3.3 and 5.3 (p<0.001). Anatomic all-inside ACL reconstruction using TransLateral technique demonstrates favourable clinical and biomechanical advantages including independent anatomic femoral tunnel placement, bone preservation and use of single tendon graft. Patients report significant improvements in pain, functional outcome, quality of life and return to sports. Mid-bundle femoral tunnel placement has been abandoned due to higher failure rate

Introduction: Recent data suggests that Double Bundle ACL reconstruction is bio-mechanically and potentially clinically superior. The success of Doudle bundle ACL reconstruction is dependent on tunnel placement. Of clinical concern is the increased technical difficulty and the potential for complications. The aim of our study was to determine how big the learning curve was for a high volume ACL Surgeon. Methods: Ten Double bundle ACL reconstruction procedures were carried out on suitable individuals. Following the procedure all patients underwent a CT scan of the relevant knee. Femoral tunnel placement was measured according to the quadrant technique described by Bernard and Hertel. The ideal tunnel locations used for analysis were those described by Zantop et al. On the tibial side, the radiographic measurements were performed according to Staubli and Rauschning. The centres of the AM and PL bundles were expressed as percentages of the maximum tibial sagittal diameter. The tibial ACL attachment at the centre of the AM bundle was taken to be 30% of the maximal tibial diameter and the centre of the PL bundle was located at 44%. The tunnel positions were measured for each patient. Results: Good tunnel placement was achieved in the majority of patients. There was an initial learning curve with improvement in tunnel placement as experience increased. Femoral tunnel positions had the greatest variation. There were no complications. The technical challenges are discussed. Conclusion: We have shown that it is possible for a high volume ACL surgeon to convert from a single bundle reconstruction technique to a double bundle reconstruction with relative accuracy

Purpose: To define the positions of the attachments of the anteromedial (AM) and posterolateral (PL) bundles of the ACL facilitating accurate tunnel placement during two-bundle reconstruction. Methods: The positions of the femoral and tibial attachments of the AM and PL bundles was determined in 7 fresh-frozen, unpaired, cadaveric knees by 6 independent observers, using landmarks visible at arthroscopy. This included, on the tibia, the retro-eminence ridge (lying just anterior to the PCL), a bony landmark that could be reliably identified arthroscopically. Tantallum beads were then inserted so that the bundle attachments could be clearly identified on a plain lateral radiograph of the knee. The position of the centres of the AM and PL attachments were described relative to Amis and Jakob’s line on the tibia and Bernard’s grid on the femur. Results: The AM femoral attachment lay high and deep in the notch with the most posterior fibres 1.8 mm anterior to the “over–the-top” position. The PL femoral attachment was low and shallow in the notch with the most anterior fibres 2.8 mm from the border of the articular cartilage. The centres of the bundles were 8.2 mm apart. The position of the bundles relative to Bernhard’s grid is shown in figure 1. On the tibia, the centre of the AM attachment was located 18 mm anterior to the Retro-eminence ridge (RER). The centre of the PL bundle lay 8.4 mm posterior to the centre of the AM bundle. These positions were at 35% and 52% along Amis and Jacob’s line. Conclusions: This study details the morphology of the AM and PL bundle attachments and demonstrates reliable arthroscopic techniques to assist with accurate tunnel placement in reconstruction surgery. In addition, it provides reference data for radiographic evaluation of tunnel placement

Purpose: The increasing number of ACL reconstructions has led to the introduction of new techniques irrespective of the fact optimal tunnel angle placement has yet to be established. Improper tunnel angle placement is associated with a variety of complications including graft failure. The purpose of this retrospective study was to compare the reliability of tibial tunnel angles produced by two experienced surgeons using a free hand method or mechanical guide (HowellTM 65° Tibial Guide). Method: Tibial tunnel angles in the coronal and sagittal planes were determined from anteroposterior and lateral radiographs, respectively, taken at 2 to 6 months postoperatively. Fifty-two sets of digital radiographs were analyzed (free hand = 28, mechanical = 24) with the knee in full extension 100 cm from the beam source. Tunnel angle measurements were calculated using NIH ImageJ software. Each angle was measured by two investigators on three separate occasions with minimum 7 days between each analysis. Results: There was a significant difference (p< 0.05) in tibial tunnel angle placement between the mechanical guide (64.76 ± 5.88) and free hand (61.11 ± 5.04) group in the coronal plane. No significant difference in tibial tunnel placement in the sagittal plane was detected (mechanical guide =73.63 ± 7.69, free hand = 73.51 ± 6.68). Intra-rater and Inter-rater reliability for measurements in the sagittal (ICC = 0.809; 0.733) and coronal (ICC = 0.69; 0.812) plane ranged from high (> 0.75) to moderate (0.75–0.40), respectively. Conclusion: Tibial tunnel angles in the coronal plane produced with a mechanical guide are more accurate than those drilled free hand when the intended angle of placement is 65°. The method used to measure tibial angles in this study was reliable within and between investigators. Further research will be conducted to investigate the correlation between tunnel angle placement and patient outcome measures