Postoperative evaluation of femoral tunnel position in ACL reconstruction: plain radiography versus computed tomography

Comparison of L1-S1 neuroforaminal dimensions derived from plain film radiography versus computed tomography

PURPOSE

To compare measurements of lumbar neuroforaminal dimensions (NFD) derived from plain film radiography (PFR) and computed tomography (CT) of young patients without spinal pathology.

METHODS

We analyzed 213 patients between 18 and 35 years of age without spinal pathology who received PFR and CT within one year of each other. NFD were defined as foraminal height, sagittal anterior-to-posterior width, and area. Statistical analyses assessed correlations and differences between PFR- and CT-derived NFD measurements.

RESULTS

111 subjects were female and 102 were male. Significant differences between PFR- and CT-derived NFD measurements were observed for all levels L1-S1, with those for foraminal height listed as follows: 4.10 mm at L1-L2, 1.58 mm at L2-L3, 3.23 mm at L3-L4, 4.27 mm at L4-L5, and 1.75 mm at L5-S1. Regarding foraminal area, these differences were 72.20, 73.45, 61.80, 35.38, and 16.18 mm2, respectively. PFR-derived measurements of NFD were larger compared to those derived from CT across all levels (p < .001). Only weak (0 ≤ r ≤ .4) or moderate (.4 ≤ r ≤ .7) correlations were observed between PFR- and CT-derived NFD measurements for all levels from L1-S1.

CONCLUSION

This study describes 9585 measurements from L1-S1 of neuroforaminal measurements derived from CT and plain film radiography from a sample of young patients without spinal pathology. Among these patients, plain film measurements of the neuroforamina are larger compared to those derived from CT for all levels from L1-S1. There is poor correlation and reliability between plain film and CT measurements of neuroforaminal dimensions.

Technology-assisted anterior cruciate ligament reconstruction improves tunnel placement but leads to no change in clinical outcomes: a systematic review and meta-analysis

PURPOSE

To investigate the effect of technology-assisted Anterior Cruciate Ligament Reconstruction (ACLR) on post-operative clinical outcomes and tunnel placement compared to conventional arthroscopic ACLR.

METHODS

CENTRAL, MEDLINE, and Embase were searched from January 2000 to November 17, 2022. Articles were included if there was intraoperative use of computer-assisted navigation, robotics, diagnostic imaging, computer simulations, or 3D printing (3DP). Two reviewers searched, screened, and evaluated the included studies for data quality. Data were abstracted using descriptive statistics and pooled using relative risk ratios (RR) or mean differences (MD), both with 95% confidence intervals (CI), where appropriate.

RESULTS

Eleven studies were included with total 775 patients and majority male participants (70.7%). Ages ranged from 14 to 54 years (391 patients) and follow-up ranged from 12 to 60 months (775 patients). Subjective International Knee Documentation Committee (IKDC) scores increased in the technology-assisted surgery group (473 patients; P = 0.02; MD 1.97, 95% CI 0.27 to 3.66). There was no difference in objective IKDC scores (447 patients; RR 1.02, 95% CI 0.98 to 1.06), Lysholm scores (199 patients; MD 1.14, 95% CI - 1.03 to 3.30) or negative pivot-shift tests (278 patients; RR 1.07, 95% CI 0.97 to 1.18) between the two groups. When using technology-assisted surgery, 6 (351 patients) of 8 (451 patients) studies reported more accurate femoral tunnel placement and 6 (321 patients) of 10 (561 patients) studies reported more accurate tibial tunnel placement in at least one measure. One study (209 patients) demonstrated a significant increase in cost associated with use of computer-assisted navigation (mean 1158€) versus conventional surgery (mean 704€). Of the two studies using 3DP templates, production costs ranging from $10 to $42 USD were cited. There was no difference in adverse events between the two groups.

CONCLUSION

Clinical outcomes do not differ between technology-assisted surgery and conventional surgery. Computer-assisted navigation is more expensive and time consuming while 3DP is inexpensive and does not lead to greater operating times. ACLR tunnels can be more accurately located in radiologically ideal places by using technology, but anatomic placement is still undetermined because of variability and inaccuracy of the evaluation systems utilized.

LEVEL OF EVIDENCE

Level III.

The incidence of tibial tunnel coalition is higher than femoral tunnel coalition in double-bundle anterior cruciate ligament reconstruction using hamstring autografts: A systematic review

INTRODUCTION

Intra-operative and postoperative coalition of tunnels may occur in double-bundle (DB) anterior cruciate ligament reconstruction (ACLR). However, the incidence and effect on clinical outcomes of tunnel coalition following primary DB ACLR using a hamstring autograft has yet be analyzed, and thus remains unknown. The objective of this systematic review was to identify the incidence of tunnel coalition upon DB ACLR using hamstring autografts and to elucidate any clinical outcomes and/or complications that tunnel coalition may have postoperatively.

HYPOTHESIS

The incidence of tunnel coalition would increase in respect to time from the index surgery, and that tunnel coalition would be related to poorer clinical outcomes compared to non-coalition cases.

METHODS

Three databases (PubMed, EMBASE, Cochrane Library) were searched in accordance with PRISMA and R-AMSTAR guidelines on June 15, 2020. Relevant studies were screened in duplicate and data regarding patient demographics, incidence of femoral and tibial tunnel coalition, and outcomes were extracted. Coalition rate was also compared between follow up at 1 month or less defined as "shorter-term", and 6 months or greater as "longer-term". Coalition is defined as the missing of a bony bridge between the two tunnels.

RESULTS

Thirty-six studies examining 1,574 patients, mean age 29.1 years, were included in this study. 29 studies (1,110 knees) reported the incidence of femoral coalition with a pooled rate of coalition of 8% (95% CI=4-12%). 28 studies (1,129 knees) reported an incidence of tibial coalition with a pooled rate of coalition of 21% (95% CI=13-30%). The incidence of tibial coalition was significantly higher than the incidence of femoral coalition across 21 comparative studies (OR=3.37, 95% CI=1.41-8.09, p=0.0065). Only two studies (111 knees) compared tunnel coalition and non-coalition groups for clinical outcome and no significant differences were observed with regards to Lysholm score, Tegner activity scale, and knee laxity measured with a KT-1000 arthrometer.

DISCUSSION

The rate of tibial tunnel coalition in DB ACLR is higher than femoral tunnel coalition, particularly at longer-term follow-up. Despite the higher radiographic evidence of coalition, the clinical effects of such remain to be ascertained, and further comparative studies are required to facilitate this understanding.

LEVEL OF EVIDENCE

IV, systematic review.

Imaging Findings of Complications After Lateral Extra-Articular Tenodesis of the Knee: A Current Concepts Review

Background:

Despite successful anterior cruciate ligament (ACL) reconstruction, many patients continue to experience persistent anterolateral rotatory instability. Lateral extra-articular tenodesis (LET) is used to address this instability by harvesting a portion of the iliotibial band, passing it underneath the fibular collateral ligament, and attaching it just proximal and posterior to the lateral femoral epicondyle. Based on the most recent clinical evidence, the addition of LET to ACL reconstruction improves clinical outcomes, which has led to an increase in the use of this technique.

Purpose:

To provide an overview of the postoperative complications of the LET procedure and their associated imaging findings, with a focus on magnetic resonance imaging (MRI).

Study Design:

Narrative review.

Methods:

In this scoping review, the authors reviewed available radiographic, computed tomography, and MRI scans of patients who experienced postoperative complications after ACL reconstruction with LET, in which the complication was determined to be from the LET procedure. Images were reviewed and subsequently described by an on-staff musculoskeletal radiologist.

Results:

The authors found 9 different complications associated with LET: graft failure, hematoma, infection, chronic pain, tunnel convergence, fixation device migration, muscular hernia, peroneal nerve palsy, and knee stiffness. They supplemented these findings with radiographic evidence from 6 patients.

Conclusion:

As extra-articular reconstruction techniques including LET become more popular among orthopaedic surgeons, it is important that radiologists and surgeons be adept at recognizing the normal imaging findings of LET and associated complications.

More anatomic tunnel placement for anterior cruciate ligament reconstruction by surgeons with high volume compared to low volume

PURPOSE

Correct placement of the femoral and tibial tunnels in the anatomic footprint during anterior cruciate ligament reconstruction (ACLR) is paramount for restoring rotatory knee stability. Recent studies have looked at surgeon volume and its outcomes on procedures such as total knee arthroplasty and infection rates, but only few studies have specifically examined tunnel placement after ACLR based on surgeon volume. The purpose of this study was to compare the placement of femoral and tibial tunnels during ACLR between high-volume and low-volume surgeons. It was hypothesized that high-volume surgeons would have more anatomic tunnel placement compared with low-volume surgeons.

METHODS

A retrospective review of all ACLR performed between 2015 and 2019 at an integrated health care system consisting of both academic and community hospitals with 68 orthopaedic surgeons was conducted. Surgeon volume was categorized as less than 35 ACLR per year (low volume) and 35 or more ACLR per year (high volume). Femoral tunnel placement for each patient was determined using an exact strict lateral radiograph (less than 6 mm of offset between the posterior halves of the medial and lateral condyles) taken after the primary ACLR using the quadrant method. The centre of the femoral tunnel was measured in relation to the posterior-anterior (PA) and proximal-distal (PD) dimensions (normal centre of anatomic footprint: PA 25% and PD 29%). Tibial tunnel placement for each patient was determined on the same lateral radiographs by measuring the mid-sagittal tibial diameter and the centre of the tibial attachment area of the ACL from the anterior tibial margin (normal centre of anatomic footprint: 43%). Each lateral radiograph was reviewed by one of two blinded reviewers.

RESULTS

A total of 4500 patients were reviewed, of which 645 patients met all the inclusion/exclusion criteria and were included in the final analysis. There were 228 patients in the low-volume group and 417 patients in the high-volume group. Low-volume surgeons performed a mean of 5 ACLRs per year, whereas surgeons in the high-volume group performed a mean of 40 ACLRs per year. In the PA dimension, the low-volume group had significantly more anterior femoral tunnel placement compared with the high-volume group (32 ± 10% vs 28 ± 9%, p < 0.01). In the PD dimension, the low-volume group had statistically significant more proximal femoral tunnel placement compared to the high-volume group (32 ± 9% vs 35 ± 9%, p < 0.01). For the tibial tunnel, the low-volume group had significantly more posterior tibial tunnel placement compared with the high-volume group (41 ± 10% vs 38 ± 7%, p < 0.01).

CONCLUSION

Low-volume surgeons placed their femoral tunnels significantly more anterior and proximal (high) during ACLR, and placed their tibial tunnels significantly more posterior, compared with high-volume surgeons. Prior research has indicated that anatomic placement of the femoral and tibial tunnels during ACLR leads to improved rotatory knee stability. The findings of this study demonstrate the importance of surgical volume and experience during ACLR.

LEVEL OF EVIDENCE

III.

How Important is the Tunnel Position in Outcomes Post-ACL Reconstruction: A 3D CT-Based Study

BACKGROUND

Drilling the femoral and tibial tunnels at their anatomical locations are critical for good outcomes and involve seeing the footprints well. We intended to compare two techniques of drilling the tunnels and the patient-reported outcomes and knee stability of patients undergoing single bundle ACL reconstruction using 3D CT to evaluate if the tunnels were anatomical or not.

MATERIALS AND METHODS

Sixty single bundle ACL reconstructions were analyzed, 30 each with Technique A and B. Pre-operative and after a minimum 27 month follow-up Lysholm, IKDC, Tegner score, hop test, and Lachman test were noted. 3D CT was done to classify femoral tunnels positions as being well placed, slightly or grossly misplaced and tibial tunnels as optimal or suboptimal and compared.

RESULTS

Sixty ACL reconstructions had full follow-up with a mean follow-up of 34 months. There was no significant difference between tunnel positions between the two techniques. Well-placed femoral tunnel had better Lysholm score (62.2 ± 16.2 v/s 48.5 ± 17.2, p 0.002) and IKDC score (62.5 ± 14.3 v/s 52.7 ± 15.1, p 0.012).). Those who had their surgeries within 3 months of their injury had better hop test (4.4 ± 0.9 v/s 3.9 ± 1, p 0.034) and IKDC scores (62.5 ± 15.8 v/s 33.2 ± 13.8, p 0.026) as compared to those that had surgery done after 3 months.

CONCLUSION

Tibial tunnel positions were optimal in most cases and did not differ between the two techniques. Well-placed femoral tunnels and surgeries done within 3 months of the injury produced best results.

Does radiological evaluation of endobutton positioning in the sagittal plane affect clinical functional results in single-bundle anterior cruciate ligament reconstruction?

INTRODUCTION

Sports injuries are increasing today due to the increased interest in sports. The most common injured knee ligament is the anterior cruciate ligament (ACL) in sport injuries. Accordingly, surgical treatment of the ACL is performed frequently. In this study, it was aimed to retrospectively evaluate whether the location of an endobutton on lateral knee radiography was effective on knee functional scores in patients who underwent ACL reconstruction.

MATERIALS AND METHODS

One hundred thirty patients who underwent ACL reconstruction between January 2015 and February 2019 were identified. The patients were divided into three groups according to the location of the endobutton on lateral radiographs taken in the postoperative period. Group 1 patients were classified as anterior, group 2 as middle, and group 3 as posterior according to the location of the endobutton. Functional scoring, physical examination tests, comparative thigh diameter measurements, and single-leg hop tests were compared between the groups. It was evaluated as to whether there was a statistically significant difference between the groups.

RESULTS

There were 38 patients in group 1, 63 patients in group 2, and 29 patients in group 3. The mean age was 29.1 in group 1, 29.1 in group 2, and 29.7 in group 3. The mean follow-up period of the patients was 18.4 months in group 1, 19.1 months in group 2, and 21.4 months in group 3. The average Lysholm score was 92.9 in group 1, 93.3 in group 2, and 91.7 in group 3. The mean modified Cincinnati scores were 27.0, 27.1, and 26.6, respectively, in the groups. The mean IKDC score of the subjective knee assessments was 92.5, 92.8, and 91, respectively, according to the groups. The average thigh atrophy value was 1 cm, 1 cm, and 1.2 cm, respectively, in the groups. In the single-leg hop test, 34 patients in group 1 jump to over 85% of the distance compared with the intact side, while 58 patients in group 2, and 23 patients in group 3 were successfully able to jump this distance. The effect of the placement of the endobutton in the anterior, middle or posterior was not statistically significant on functional scores and physical examination results. In patients with endobuttons in the middle, functional scores were found better than in those with anterior or posterior placement.

CONCLUSIONS

No statistically significant differences were found in clinical functional results when comparing patients' endobutton location on femur. For this reason, surgical time should not be extended using unnecessary extra effort to change the orientation of the exit hole during surgery.

Do Rotation and Measurement Methods Affect Reliability of Anterior Cruciate Ligament Tunnel Position on 3D Reconstructed Computed Tomography?

Background:

The literature has seldom investigated the anterior cruciate ligament (ACL) tunnel position while considering the effect of rotation of 3-dimensional computed tomography (3D-CT) images during measurements.

Hypothesis:

We hypothesized that (1) measurement of the ACL tunnel position in the femur and tibia through use of 3D-CT is considerably influenced by rotation of the 3D model and (2) there exists a reliable measurement method for ACL tunnel position least affected by rotation.

Study Design:

Controlled laboratory study.

Methods:

The 3D-CT images of 30 randomly selected patients who underwent single-bundle ACL reconstruction were retrospectively reviewed. For femoral tunnel assessments, rectangular reference frames were used that involved the highest point of the intercondylar notch and outer margins of the lateral femoral condyle (method 1), the highest point of the intercondylar notch and outer margins of the lateral wall of the intercondylar notch (method 2), and the lowest point of the intercondylar notch and outer margins of the lateral femoral condyle (method 3). For tibial tunnel assessments, rectangular reference frames with the cortical outline at the articular surface of the tibia (method A) and the cortical outline of the proximal tibia (method B) were used. For both femoral and tibial assessments, the tunnel positions at 5°, 10°, and 15° of rotation of the 3D model were compared with that at a neutral position.

Results:

The values measured by methods 1 and 3 showed significant differences at greater than 5° of rotation compared with the value at the neutral position, whereas method 2 showed relatively consistent results. However, the values measured with both methods A and B showed significant differences at greater than 5° of rotation compared with the value at the neutral position.

Conclusion:

The tunnel position on 3D-CT images was significantly influenced by rotation during measurements. For femoral tunnel position, measurement with a reference frame using the lateral wall of the intercondylar notch (method 2) was the least affected by rotation, with relatively consistent results.

Clinical Relevance:

This study demonstrates that measurement using the lateral wall of the intercondylar notch might be a consistent and reliable method for evaluating the ACL femoral tunnel position considering the effect of 3D-CT image rotation during measurements. However, both methods to measure tibial tunnel position described in this study were similarly affected by rotation.

The quadrant method measuring four points is as a reliable and accurate as the quadrant method in the evaluation after anatomical double-bundle ACL reconstruction

PURPOSE

The quadrant method was described by Bernard et al. and it has been widely used for postoperative evaluation of anterior cruciate ligament (ACL) reconstruction. The purpose of this research is to further develop the quadrant method measuring four points, which we named four-point quadrant method, and to compare with the quadrant method.

METHODS

Three-dimensional computed tomography (3D-CT) analyses were performed in 25 patients who underwent double-bundle ACL reconstruction using the outside-in technique. The four points in this study's quadrant method were defined as point1-highest, point2-deepest, point3-lowest, and point4-shallowest, in femoral tunnel position. Value of depth and height in each point was measured. Antero-medial (AM) tunnel is (depth1, height2) and postero-lateral (PL) tunnel is (depth3, height4) in this four-point quadrant method. The 3D-CT images were evaluated independently by 2 orthopaedic surgeons. A second measurement was performed by both observers after a 4-week interval. Intra- and inter-observer reliability was calculated by means of intra-class correlation coefficient (ICC). Also, the accuracy of the method was evaluated against the quadrant method.

RESULTS

Intra-observer reliability was almost perfect for both AM and PL tunnel (ICC > 0.81). Inter-observer reliability of AM tunnel was substantial (ICC > 0.61) and that of PL tunnel was almost perfect (ICC > 0.81). The AM tunnel position was 0.13% deep, 0.58% high and PL tunnel position was 0.01% shallow, 0.13% low compared to quadrant method.

CONCLUSIONS

The four-point quadrant method was found to have high intra- and inter-observer reliability and accuracy. This method can evaluate the tunnel position regardless of the shape and morphology of the bone tunnel aperture for use of comparison and can provide measurement that can be compared with various reconstruction methods. The four-point quadrant method of this study is considered to have clinical relevance in that it is a detailed and accurate tool for evaluating femoral tunnel position after ACL reconstruction.

LEVEL OF EVIDENCE

Case series, Level IV.

Radiological evaluation of the femoral tunnel positioning in anterior cruciate ligament reconstruction

OBJECTIVE

To evaluate the inclination and the length of the femoral tunnel in patients submitted to anterior cruciate ligament reconstruction (ACL) surgery by transtibial and anatomical techniques.

METHODS

This is an analytical observational study in patients with ACL injury that underwent arthroscopic reconstruction through transtibial and anatomical surgical techniques. In the immediate postoperative period, computed tomography (CT) and anteroposterior (AP) view digital radiographs (X-rays) were performed to evaluate the inclination and length of the femoral tunnel.

RESULTS

Forty-two patients were analyzed: 27 underwent anatomical reconstruction and 15, transtibial reconstruction. The inclination angle and tunnel length by the transtibial technique are always greater than by the anatomical technique. The mean inclination angles were 59.75° (53.9-66.1°) in the X-rays and 54.17° (43.5-62.3°) in CT for the transtibial technique, and 42.91° (29.3-57.4°) in the X-rays and 39.10° (23.8-50.6°) in CT for the anatomical technique. Regarding the length of the femoral tunnel, the transtibial technique promotes longer tunnels: mean 55.7 mm (40.0-70.2 mm) in the transtibial and 35.5 mm (24.5-47 mm) in the anatomical technique. No statistically significant correlation was observed between the length and the inclination of the tunnel, regardless of the technique used. Thus, these variables can be considered as independent.

CONCLUSION

The anatomical reconstruction technique presented shorter femoral tunnels and lower angle of inclination than the transtibial technique. The CT showed smaller inclination angle than the X-rays, regardless of the surgical technique.

Validation of an MRI Protocol for Routine Quantitative Assessment of Tunnel Position in Anterior Cruciate Ligament Reconstruction

BACKGROUND

No standardized methodology and objective criteria currently exist to accurately and objectively assess tunnel placement and consequent graft orientation in anterior cruciate ligament (ACL) reconstruction (ACLR) through a single imaging modality. Advances in magnetic resonance imaging (MRI) technology have enabled the use of volumetric high spatial and contrast resolution proton density-weighted sequencing, which allows precise delineation of graft orientation, tunnel position, and quantitative assessment of tunnel position relationship to adjacent reproducible anatomic landmarks.

PURPOSE

To establish an MRI protocol that would provide an accurate alternative to 3-dimensional computed tomography (3D-CT) for standardized assessment of bone tunnel placement in ACLR, as a component of assessing ACLR outcomes and to assist in presurgical planning for revision ACLR.

STUDY DESIGN

Cohort study (diagnosis); Level of evidence, 2.

METHODS

Twenty-four participants diagnosed with a failed ACLR underwent MRI and 3D-CT per the imaging protocols of the Sydney Orthopaedic Research Institute, in which the acquired data were converted to 3D models. The bone tunnels of the previous ACLR were then intraoperatively digitized at the tunnel aperture and along the length of the tunnel (barrel) and used as the reference standard to evaluate the accuracy of high-resolution MRI and 3D-CT. Differences in geometry between the image-based model and the reference point cloud were calculated through point-to-point comparison.

RESULTS

At the tunnel apertures, no significant differences were detected between the MRI and 3D-CT models versus the reference models for the femur ( P = .9472) and tibia ( P = .5779). Mean ± SD tunnel barrel deviations between MRI and 3D-CT were 0.48 ± 0.28 mm (femur) and 0.46 ± 0.27 mm (tibia). No significant differences were detected between the MRI and 3D-CT models versus the reference models for the femoral ( P = .5730) and tibial ( P = .3002) tunnel barrels.

CONCLUSION

This study demonstrated that, in addition to being the optimum modality for assessment of soft tissue injury of the knee, a high-resolution 3D turbo spin echo proton density sequence can provide an accurate assessment of tunnel placement, without the use of ionizing radiation. Therefore, this protocol provides the foundation for an objective standardized platform to quantitatively evaluate the location of ACL bone tunnels and graft orientation for routine postoperative assessment, presurgical planning, and evaluation of clinical outcomes.

Intraoperative Graft Isometry in Anatomic Single-Bundle Anterior Cruciate Ligament Reconstruction

Purpose

Little is known about the isometry of anatomic single-bundle anterior cruciate ligament (ACL) tunnel positions in vivo although it is closely related to graft tension throughout the range of motion. The purpose of this study was to evaluate intraoperative graft isometry in anatomic single-bundle ACL reconstruction in vivo.

Materials and Methods

Graft length changes were assessed before bio-screw fixation in the tibial tunnel by pulling the graft with tensions of 20 lbs and 30 lbs in full extension at flexion angles of 30°, 60°, 90°, and 120°.

Results

At the flexion angle of 30°, 20 lbs and 30 lbs of tension showed −0.4 mm and −0.6 mm length changes, respectively. The greater the flexion angle of the knee, the shorter the graft length in the joint. At the flexion angles of 90° and 120°, there was significant difference in the graft length change between 20 lbs and 30 lbs of tension.

Conclusions

Anatomic single-bundle ACL reconstruction was non-isometric. The graft length was the longest in full extension. The tension of graft became loose in flexion. At the flexion angles of 90° and 120°, there was significant difference in the graft length change between 20 lbs and 30 lbs of tension.

The posterior horn of the lateral meniscus is a reliable novel landmark for femoral tunnel placement in ACL reconstruction

PURPOSE

Femoral tunnel placement is essential for good outcome in anterior cruciate ligament (ACL) reconstruction. In the past, several attempts have been made to optimize femoral tunnel placement. It was observed that the posterior horn of the lateral meniscus was always located directly below to the desired femoral ACL tunnel position, when the knee was brought to deep flexion (> 120°). The goal of the present study was to verify the hypothesis that the posterior horn of the lateral meniscus can be used as a landmark for femoral tunnel placement.

METHODS

Out of a consecutive series of ACL reconstructions done by a single surgeon, 55 lateral radiographs were evaluated according to the quadrant method by Bernard and Hertel. Additionally, on anterior-posterior radiographs the femoral tunnel angle was determined.

RESULTS

In the present case series the posterior horn of the lateral meniscus could be identified and used as a landmark for femoral tunnel placement in all cases. The mean tunnel depth was 24 ± 5.1% and the mean tunnel height was 31.3 ± 5.7%. The mean femoral tunnel angle was 41 ± 4.9° using the anatomical axis as a reference. Compared to previous cadaver studies the data of the present study were within their anatomical range of the native ACL insertion site.

CONCLUSION

The suggested technique using the posterior horn of the lateral meniscus as a landmark for femoral tunnel placement showed reproducible results and matches the native ACL insertion site compared to previous cadaveric studies. In particular, non-experienced ACL surgeons will benefit from this apparent landmark and the corresponding easy-to-use ACL reconstruction method.

LEVEL OF EVIDENCE

IV.

Plain radiographs can be used for routine assessment of ACL reconstruction tunnel position with three-dimensional imaging reserved for research and revision surgery

PURPOSE

The position of the osseous tunnels and graft during anterior cruciate ligament (ACL) reconstruction has been the subject of multiple studies aiming for either anatomical placement or an alternative. The assessment of these positions, using post-operative imaging, is therefore of interest to the surgeon in both the evaluation of surgical performance and surveillance of potential complications. The purpose of this review is to identify the optimal use of imaging in both the surveillance of clinical practice and in planning revision surgery.

METHODS

A comprehensive systematic review was performed using Medline and Pubmed searches to identify radiological methods used to assess ACL reconstruction tunnel position. Commonly used methods were identified with correlation to either native anatomy or clinical results.

RESULTS

The findings suggest that plain radiographs can be used to assess tunnel position and identify grafts that are positioned non-anatomically and may be at increased risk of complications. Computer tomography (CT) offers additional information about the tunnel aperture shape and size that is of importance for revision surgery and research projects whilst magnetic resonance imaging (MRI) provides further assessment of both graft integrity and associated soft tissue damage.

CONCLUSION

In the surveillance of routine clinical practice, plain radiographs are sufficient to define tunnel position. The additional information provided by three-dimensional imaging is only required in revision surgery or research studies.

LEVEL OF EVIDENCE

IV.

Editorial Commentary: Prognosticators for Outcomes After Anterior Cruciate Ligament Reconstruction…Time to Beat a Different Dead Horse?

The outcomes of anterior cruciate ligament reconstruction, be it single or double bundle, continue to be analyzed with exhaustion. There is strong evidence regarding the measurable effects of femoral tunnel position as well as the contributions that age, time to surgery, and concomitant pathology have on outcomes of this procedure. We are surgeons with big egos. We like to think that what we do in surgery is all that dictates the outcome. Maybe it is time to broaden the focus of our investigation.

Loss of Internal Tibial Rotation After Anterior Cruciate Ligament Reconstruction

The flexion angle of the knee and the position of the tibia need to be considered during tensioning of the anterior cruciate ligament (ACL) graft to avoid overconstraining the knee. The purpose of this report was to describe 2 cases of loss of tibial internal rotation after single-bundle anatomic ACL reconstruction with graft tensioning in flexion. Retrospective review of each patient's operative chart revealed that the graft was tensioned in flexion and placed in an anatomic position in the femoral tunnel at the time of the index operation. Primary outcome was ACL revision surgery. Secondary outcome data included Lysholm scores and Lachman and pivot shift tests. Two patients underwent revision ACL reconstruction with a more vertical tunnel placed through a transtibial technique. The graft was tensioned in full knee extension and neutral rotation of the tibia. This resulted in restoration of normal tibial internal rotation to 10°. Lysholm scores improved from 35 to 90 in patient 1 and from 12 to 61 in patient 2. Patient 1 returned to college soccer at 6 months postoperatively. Her knee was stable to Lachman and pivot shift tests. Patient 2 has been followed for 12 months and has returned to all normal activities without pain or dysfunction. Anatomic femoral placement of the ACL with improper positioning of the knee during tensioning of the graft may capture the knee and lead to loss of the normal internal rotation. The surgeon should be aware of this complication during primary ACL reconstruction. [Orthopedics. 2018; 41(1):e22-e26.].

Tunnel positioning assessment after anterior cruciate ligament reconstruction at 12months: Comparison between 3D CT and 3D MRI. A pilot study

BACKGROUND

Tunnel positioning assessment is a major issue after anterior cruciate ligament (ACL) reconstruction surgery. Historically, it used plain X-ray and, more recently, CT with 3D reconstruction. MRI is a reliable method of assessing ACL graft integrity and postoperative complications. To our knowledge, there have been no studies of efficacy in tunnel positioning assessment. The aim of this study was to assess the efficacy of 3D MRI in assessing femoral and tibial tunnel positioning after ACL reconstruction. The hypothesis was that 3D MRI sequences with reconstruction are as accurate as 3D CT for tunnel positioning assessment in ACL reconstruction.

METHODS

Twenty-two patients who underwent an arthroscopic ACL reconstruction using hamstring graft were included in a prospective study. All patients were examined on 3D CT and 3D MRI at 12months post-surgery. Tunnel positioning was assessed on both imaging systems by a musculoskeletal radiologist and an orthopedic surgeon specialized in knee arthroscopy, both blind to all clinical data.

RESULTS

No statistically significant difference was found between 3D CT and 3D MRI on coronal and sagittal reconstructions. For coronal assessment of tibial tunnel orifice, sagittal assessment of tibial tunnel orifice and sagittal assessment of femoral tunnel orifice, P-values ranged from 0.37 to 0.99, 0.051 to 0.64 and 0.19 to 0.59, respectively. For tibial and femoral tunnel angulation, P-values were respectively 0.52 and 0.29.

CONCLUSION

3D MRI is a reliable method to assess femoral and tibia tunnel positioning in ACL reconstruction, compared to 3D CT as gold standard. Indeed, in our opinion 3D MRI could in the future replace CT for ACL reconstruction assessment, concerning not only the meniscus and ligaments but also tunnel position.

LEVEL OF EVIDENCE

Level 3; comparative prospective study.

Tunnel malpositions in anterior cruciate ligament risk cartilaginous changes and bucket-handle meniscal tear: Arthroscopic survey in both primary and revision surgery

OBJECTIVES

There are not many chances to arthroscopically reassess how graft tunnel malpositions in primary anterior cruciate ligament reconstruction (ACLR) associate with intra-articular degeneration in revision ACLR. This study was aimed to evaluate whether radiographic tunnel position in primary ACLR affect cartilaginous changes and bucket-handle meniscus tears in revision ACLR.

METHODS

Thirty-five patients who underwent revision ACLR were recruited; their primary surgeries were single-bundle reconstructions. Tunnel positions were evaluated using the plain radiographs after primary surgery. The sagittal tunnel positions of the femur (FP) and tibia (TP) were determined on the lateral view. The articular cartilage was evaluated arthroscopically at primary and revision surgery using the International Cartilage Repair Society (ICRS) score. A progression of two grades was considered as cartilaginous changes. Meniscal tears were evaluated with an arthroscopic probe. Logistic regression analysis was conducted using the prevalence of cartilaginous changes or bucket-handle meniscus tears as the dependent variable; tunnel parameters were used as the independent variables.

RESULTS

Seven patients (20.0%) had cartilaginous changes and nine patients (25.7%) had bucket-handle tears in the medial meniscus. In logistic regression analysis, %FP [odds ratio (OR): 1.212; P = 0.007] and the cut-off of 60% in the FP (OR: 22.000; P = 0.008) were correlated with cartilaginous changes. %TP (OR: 1.126; P = 0.036) was correlated with the prevalence of bucket-handle meniscus tears.

CONCLUSIONS

Anterior femoral tunnel malposition in the femur was associated with the cartilaginous changes, and posterior tibial tunnel malposition with the development of bucket-handle meniscus tears.

Three dimensionalCT analysis of femoral tunnel position after ACL reconstruction. A prospective study of one hundred and thirty five cases

BACKGROUND

One of the principal causes for failure of anterior cruciate ligament reconstruction (ACL) is femoral tunnel mal-position. Several studies compare the position of femoral tunnels achieved with various techniques, with small series and using a quadrant assessment method.

QUESTIONS

(1) What is the incidence of anatomical positioning of the intra-articular femoral tunnel aperture in primary ACL reconstruction in a university knee surgery? (2) What are the main errors in positioning?

METHODS

3D-CT scans were performed after primary ACL reconstruction in 135 consecutive cases. The intra-articular position of the femoral tunnel aperture was analyzed using the Magnussen classification.

RESULTS

The intra-articular tunnel position was deemed anatomical in 77%, intermediate in 20.8%, and non-anatomical in 2.2%. Among the mal-positioned tunnels, 54.8% were vertical, 29% were anteriorly positioned, and 16.1% were both.

CONCLUSIONS

The intra articular femoral tunnel aperture was well positioned using an outside-in technique. The main error of tunnel positioning was a tunnel too vertical.

LEVEL OF EVIDENCE

Level III, prospective study (case series).

The Anatomic Centers of the Femoral and Tibial Insertions of the Anterior Cruciate Ligament: A Systematic Review of Imaging and Cadaveric Studies Reporting Normal Center Locations

BACKGROUND

The anterior cruciate ligament (ACL) is regularly reconstructed if knee joint function is impaired. Anatomic graft tunnel placement, often assessed with varying measurement methods, in the femur and tibia is considered important for an optimal clinical outcome. A consensus on the exact location of the femoral and tibial footprint centers is lacking.

PURPOSE

To systematically review the literature regarding anatomic centers of the femoral and tibial ACL footprints and assess the mean, median, and percentiles of normal centers.

STUDY DESIGN

Systematic review.

METHODS

A systematic literature search was performed in the PubMed/Medline database in November 2015. Search terms were the following: "ACL" and "insertion anatomy" or "anatomic footprint" or "radiographic landmarks" or "quadrant methods" or "tunnel placement" or "cadaveric femoral" or "cadaveric tibial." English-language articles that reported the location of the ACL footprint according to the Bernard and Hertel grid in the femur and the Stäubli and Rauschning method in the tibia were included. Weighted means, weighted medians, and weighted 5th and 95th percentiles were calculated.

RESULTS

The initial search yielded 1393 articles. After applying the inclusion and exclusion criteria, 16 studies with measurements on cadaveric specimens or a healthy population were reviewed. The weighted mean of the femoral insertion center based on measurements in 218 knees was 29% in the deep-shallow (DS) direction and 35% in the high-low (HL) direction. The weighted median was 26% for DS and 34% for HL. The weighted 5th and 95th percentiles for DS were 24% and 37%, respectively, and for HL were 28% and 43%, respectively. The weighted mean of the tibial insertion center in the anterior-posterior direction based on measurements in 300 knees was 42%, and the weighted median was 44%; the 5th and 95th percentiles were 39% and 46%, respectively.

CONCLUSION

Our results show slight differences between the weighted means and medians in the femoral and tibial insertion centers. We recommend the use of the 5th and 95th percentiles when considering postoperative placement to be "in or out of the anatomic range."

Influence of change of tunnel axis angle on tunnel length during double-bundle ACL reconstruction via the transportal technique

BACKGROUND

Commercially available flexible reamer and curved guide systems allow a certain degree of control over intra-articular tunnel orientation, therefore allows a wide range of intra-osseous femoral tunnel orientations, contrary to the femoral tunneling technique using a straight guide pin, which are determined by knee flexion angle. We sought to find the clinical relevance of intra-osseous femoral tunnel orientations in the respect of tunnel length. To evaluate the relationship between the tunnel axis angle in three orthogonal planes and tunnel length in the anteromedial (AM) and posterolateral (PL) femoral tunnels in patients who underwent anatomic double-bundle anterior cruciate ligament reconstruction (DB-ACLR) using the transportal (TP) technique with a 42^o curved guide.

METHODS

A total of 40 patients who underwent primary DB-ACLR with the TP technique using a curved guide were evaluated retrospectively. The tunnel axis angle in three orthogonal planes were evaluated on a three-dimensional surface model constructed using an axial computed tomography scan obtained after reconstruction. Then, correlations with tunnel length were analyzed.

RESULTS

In the AM tunnel, tunnel axis angles in the coronal (β = 0.0252, p = 0.022) and sagittal (β = 0.0168, p = 0.029) plane showed significant correlations with tunnel length, while the axial plane did not (p = 0.493) (adjusted R² = 0.801). In the PL tunnel, only tunnel axis angles in the axial plane (β = 0.0262, p = 0.008) showed a significant relationship with tunnel length (adjusted R² = 0.700).

CONCLUSION

Drilling at a higher angle in the coronal and sagittal planes in AM tunnels and at a higher angle in the axial plane in PL tunnels decreases the incidence of short femoral tunnels.

In-out versus out-in technique for ACL reconstruction: a prospective clinical and radiological comparison

Background

Several studies have recently shown better restoration of normal knee kinematics and improvement of rotator knee stability after reconstruction with higher femoral tunnel obliquity. The aim of this study is to evaluate tunnel obliquity, length, and posterior wall blowout in single-bundle anterior cruciate ligament (ACL) reconstruction, comparing the transtibial (TT) technique and the out–in (OI) technique.

Materials and methods

Forty consecutive patients operated on for ACL reconstruction with hamstrings were randomly divided into two groups: group A underwent a TT technique, while group B underwent an OI technique. At mean follow-up of 10 months, clinical results and obliquity, length, and posterior wall blowout of femoral tunnels in sagittal and coronal planes using computed tomography (CT) scan were assessed.

Results

In sagittal plane, femoral tunnel obliquity was 38.6 ± 10.2° in group A and 36.6 ± 11.8° in group B (p = 0.63). In coronal plane, femoral tunnel obliquity was 57.8 ± 5.8° in group A and 35.8 ± 8.2° in group B (p = 0.009). Mean tunnel length was 40.3 ± 1.2 mm in group A and 32.9 ± 2.3 mm in group B (p = 0.01). No cases of posterior wall compromise were observed in any patient of either group. Clinical results were not significantly different between the two groups.

Conclusions

The OI technique provides greater obliquity of the femoral tunnel in coronal plane, along with satisfactory length of the tunnel and lack of posterior wall compromise.

Level of evidence

II, prospective study.

Anatomic ACL reconstruction: the normal central tibial footprint position and a standardised technique for measuring tibial tunnel location on 3D CT

PURPOSE

The aim of this study was to define the normal ACL central tibial footprint position and describe a standardised technique of measuring tibial tunnel location on 3D CT for anatomic single-bundle ACL reconstruction.

METHODS

The central position of the ACL tibial attachment site was determined on 76 MRI scans of young individuals. The central footprint position was referenced in the anterior-posterior (A-P) and medial-lateral (M-L) planes on a grid system over the widest portion of the proximal tibia. 3D CT images of 26 young individuals had a simulated tibial tunnel centred within the bony landmarks of the ACL footprint, and the same grid system was applied over the widest portion of the proximal tibia. The MRI central footprint position was compared to the 3D CT central footprint position to validate the technique and results.

RESULTS

The median age of the 76 MRI subjects was 24 years, with 32 females and 44 males. The ACL central footprint position was at 39 (±3 %) and 48 (±2 %), in the A-P and M-L planes, respectively. There was no significant difference in this position between sexes. The median age of the 26 CT subjects was 25.5 years, with 10 females and 16 males. The central position of the bony ACL footprint was at 38 (±2 %) and 48 (±2 %), in the A-P and M-L planes, respectively. The MRI and CT central footprint positions were not significantly different in relation to the medial position, but were different in relation to the anterior position (A-P 39 % vs. 38 %, p = 0.01). The absolute difference between the central MRI and CT reference positions was 0.45 mm.

CONCLUSIONS

The ACL's normal central tibial footprint reference position has been defined, and the technique of measuring tibial tunnel location with a standardised grid system is described. This study will assist surgeons in evaluating tibial tunnel position in anatomic single-bundle ACL reconstruction.

LEVEL OF EVIDENCE

III.

Anterior cruciate ligament reconstruction tunnel size: causes of tunnel enlargement and implications for single versus two-stage revision reconstruction

Anterior cruciate ligament (ACL) reconstructions have increased over the past 25 years. The increased incidence of ACL reconstructions has translated into a larger number of graft failures and revision ACL procedures. It is important to understand the causes of graft failure when evaluating for a revision ACL reconstruction and to appreciate changes in tunnel anatomy over time prior to planning revision surgery. In this manuscript, tunnel size for ACL reconstruction and implications for single-stage versus two-stage revision ACL reconstruction will be discussed, as well as causes of tunnel enlargement, including mechanical and biological factors.

COMPARISON BETWEEN RENDERING 3D-CT AND TRANSPARENT 3D-CT IN ACL TUNNEL POSITIONING

Objective:

To compare the transparent 3D computed tomography (CT) image protocol against conventional 3D-CT image-rendering protocol to assess femoral tunnel position in anatomic anterior cruciate ligament (ACL) reconstructions.

Methods:

Eight knee CT scans from cadavers were analyzed by image rendering 3D-CT protocol, using Rhinoceros^(r) software. The central point of the ACL tunnel was set using the sagittal plane. Same CT scans were analyzed using transparent 3D-CT measurement protocol with OsiriX^(r) software. Central point of the ACL tunnel was set using sagittal, coronal and axial planes. The grid system described by Bernard and Hertel was used to compare tunnel positions between protocols, using height and length parameters.

Results:

There was a significant difference between measurements using image rendering 3D-CT and transparent 3D-CT protocol for height (23.8 ± 7.9mm and 33.0 ± 5.0mm, respectively; p=0.017) and no differences for length (18.6 ± 4.2mm and 18.3 ± 4.5mm, respectively; p=0.560).

Conclusion:

Height in transparent CT protocol was different and length was the same as compared to 3D-CT rendering protocol in Bernard and Hertel method for tunnel measurements. Level of Evidence II, Descriptive Laboratory Study.

Reliability of 3-Dimensional Computed Tomography for Application of the Bernard Quadrant Method in Femoral Tunnel Position Evaluation After Anatomic Anterior Cruciate Ligament Reconstruction

PURPOSE

To validate whether the Bernard quadrant method, which was developed for application on simple lateral radiography, can be used with 3-dimensional computed tomography (3D CT) to localize the femoral insertion of the reconstructed anterior cruciate ligament (ACL).

METHODS

We analyzed 32 knees with ACL tears that were reconstructed using a metal interference screw for fixation at the femoral tunnel between March 2012 and May 2013. Postoperative lateral radiographs and 3D CT images were obtained 7 days after the operation. By use of the Bernard quadrant method, the location of the femoral tunnel was measured by 2 orthopaedic surgeons by locating the position of the metal interference screw using 3D CT imaging and simple lateral knee radiography. The correlation between the femoral tunnels on the 2 radiographic images was compared using the MedCalc statistical analysis program.

RESULTS

On the 3D CT image, the position of the femoral insertion of the ACL as measured by the position of the metal screw head was 36.3% ± 6.0% in the x-coordinate and 39.6% ± 9.1% in the y-coordinate compared with 37.6% ± 5.8% and 41.0% ± 11.6%, respectively, on the simple radiograph. The Pearson correlation coefficients between 3D CT and simple radiography were 0.840 for the x-coordinate and 0.858 for the y-coordinate. Intraobserver reliability and interobserver reliability for both coordinates were greater than 0.9 on 3D CT.

CONCLUSIONS

Application of the Bernard quadrant method on 3D CT showed high correlation to the originally described method using lateral radiographs and can be used reliably for localizing the reconstructed ACL.

LEVEL OF EVIDENCE

Level III, diagnostic study.

Two-Stage Revision Anterior Cruciate Ligament Reconstruction

The number of primary anterior cruciate ligament (ACL) tears is rapidly increasing. In patients who wish to return to their preoperative level of function, specifically as it pertains to participation in sports, the gold standard of treatment following an ACL tear remains an anterior cruciate ligament (ACL) reconstruction. Despite a majority of good/excellent results following primary ACL reconstruction, there is a growing subset of patients with persistent or recurrent functional instability who require revision ACL reconstruction. Preoperative planning for revision ACL reconstruction requires a careful understanding of the root cause of ACL failure, including possible technical causes of primary ACL failure and the presence of combined knee pathology that was not addressed at the index ACL reconstruction. The decision to perform 2-stage revision ACL reconstruction is multifactorial and is reached by technical considerations that may make a 1-stage revision less optimal, including tunnel widening, arthrofibrosis, active infection, and others. Concomitant knee pathology such as meniscal deficiency, malalignment (including an increase in posterior tibial slope), chondral lesions, and other ligamentous laxity may also require a staged approach to treatment. This evidence-based review covers the indications for 2-stage revision ACL reconstruction, surgical techniques, evidence for and technique of bone grafting prior ACL tunnels, and outcomes of 2-stage revision stratified by initial cause of ACL reconstruction failure. With proper preoperative planning and an understanding of the cause of failure following the primary ACL reconstruction, revision ACL reconstruction can offer excellent outcomes in the motivated patient. [Orthopedics. 2016; 39(3):e456-e464.].

CT assessment of femoral tunnel placement after partial ACL reconstruction

INTRODUCTION

When one of the anterior cruciate ligament (ACL) bundles is torn, it seems appropriate to preserve the remaining bundle to improve the vascularization and proprioception of the graft, and to reproduce the attachment sites of the torn bundle. After ACL reconstruction, the functional result is worse when the tunnels are positioned further away from the native ACL's isometric attachment points. The goal of this study was to use CT 3D reconstructions to analyse the position of the femoral tunnel following partial ACL reconstruction and to compare it to complete ACL reconstruction cases. We hypothesized that the femoral tunnel positioning was optimal during partial ACL reconstruction.

METHODS

In this prospective single-centre study, 16 patients who underwent isolated anteromedial bundle reconstruction were evaluated during the immediate postoperative period using 3D reconstruction of CT images. During this same period, 180 patients who underwent complete ACL reconstruction in the same surgery unit served as a control group.

RESULTS

In the partial ACL reconstruction group, 6 tunnels (37.5%) were in the optimal position and 10 tunnels (62.5%) were not. In the complete ACL reconstruction group, 124 femoral (68.9%) were in the optimal position and 56 (31.1%) were not (P<0.05).

DISCUSSION

Femoral tunnel positioning is not always optimal in patients who undergo partial ACL reconstruction. Three-dimensional CT reconstruction is a good tool to help surgeons detect and learn from their errors.

LEVEL OF EVIDENCE

III (case-control study).

Measurements of tunnel placements after anterior cruciate ligament reconstruction--A comparison between CT, radiographs and MRI

BACKGROUND

A non-anatomic placement of the femoral and tibial tunnels may affect outcome in anterior cruciate ligament (ACL) reconstructions. Tunnel placements are validated with varying imaging modalities. We compared measurements of tunnel placements between radiographs, computed tomography (CT) and magnetic resonance imaging (MRI) in a clinical setting, assessed the reliability and aimed to decide on a possible "gold standard".

METHODS

All patients who had undergone at least two of three modalities, radiographs, MRI and CT, after ACL reconstruction between January 2011 and June 2013 were included. Two radiologists measured tunnel placements according to a standardized protocol. Interobserver agreement was assessed with intraclass correlation coefficients (ICC), the intermodality differences with Bland-Atman plots. Radiation data for CT studies were collected.

RESULTS

Forty-six CTs, 45 radiographs and 30 MRIs were reviewed. Femoral inter-observer agreement for radiographs was ICC=0.64, for CT ICC=0.86 and for MRI ICC = 0.75. Tibial inter-observer agreement for radiographs was ICC=0.92, for CT-mip ICC=0.91, for CT and MRI ICC = 0.87. No intermodality differences between the femoral measurements were observed. In the tibia, there were differences between radiographs and CT (-3.9%), radiographs-MRI (-3.6%), CT-CT mip (3.2%) and CTmip-MRI (-3.1%). The effective radiation doses varied between 0.025 and 0.045 mSv, mean and median was 0.033 mSv.

CONCLUSION

There were differences in the tibial measurements between summation and single slice images. Only 3D-CT depicted the femoral tunnel in both directions. CT was consistently reliable in both femoral and tibial measurements. Effective radiation dose from CT was lower than previously reported. CT can safely be used in routine clinical practice to evaluate tunnel placements after ACL reconstruction.

Position of anterior cruciate ligament after single-bundle arthroscopic reconstruction

PURPOSE

The goal of this study was to assess the position of the reconstructed anterior cruciate ligament (ACL) in arthroscopic single-bundle ligamentoplasties through an anteromedial portal technique based on a clinical case series of 74 patients followed prospectively.

METHODS

This cohort study involved 100 patients who underwent arthroscopic ACL reconstruction between January 2012 and January 2014. Patients who underwent isolated ACL reconstruction were selected from 194 cases with associated lesions. Graft placement at the femoral side was within the femoral footprint of ACL. All patients received computed tomography scans and magnetic resonance imaging of both knees to compare ACL graft position to tht of the native ACL in the unaffected knee and to show whether drilling the femoral tunnel through the anteromedial portal closely approximates the native ACL alignment.

RESULTS

Seventy-four patients were available for follow-up. Mean value for the sagittal angle was 52.6° ± 2.9° for the graft-Blumensaat angle was 4.73° ± 0.75°., closely matching measurements in the contralateral normal knee.

CONCLUSION

Using the anteromedial portal for single-bundle arthroscopic ACL reconstruction enables graft positioning within the normal footprint and as close as possible to anatomic ACL orientation.

A modified quadrant method for describing the femoral tunnel aperture positions in ACL reconstruction using two-view plain radiographs

PURPOSE

A modified quadrant method was developed for description of femoral tunnel aperture positions on the sagittal plane after double-bundle anterior cruciate ligament (ACL) reconstruction, which can be measured by using two-view radiographs. The purpose of the study is to provide a new measurement method and to evaluate the reproducibility and accuracy of the method.

METHODS

Forty-one patients who had undergone a double-bundle ACL reconstruction were investigated. Two-view plain radiographs, a 45-degree-flexion posterior-anterior standing (Rosenberg) and a lateral view, were taken at 1 year postoperatively, and the femoral tunnel positions were measured. Intra- and inter-observer reproducibility was calculated by means of intra-class correlation coefficient (ICC). Also, the accuracy of the method was evaluated by comparing the measurement from three-dimensional computed tomography (3D-CT).

RESULTS

Intra-observer reproducibility was excellent (ICC > 0.9). Inter-observer reproducibility of antero-medial (AM) tunnel position was almost perfect (ICC > 0.8) and that of postero-lateral (PL) tunnel was substantial (ICC > 0.7). The accuracy of the method was assessed by comparing the measurement from 3D-CT and was found to be almost perfect (ICC > 0.8). With the modified quadrant method, the average height of AM and PL tunnels were 17.8 and 44.4 %, respectively, and the depth of AM and PL tunnels were 25.5 and 36.7 %, respectively.

CONCLUSIONS

A modified quadrant method was found to have acceptable reproducibility and accuracy. The method is useful for describing the femoral tunnel aperture positions in ACL reconstruction because of its easiness and simplicity. By using this method, it is possible to analyse the femoral tunnel position even in the cases without CT analysis.

LEVEL OF EVIDENCE

IV.

Farmedial versus anteromedial portal drilling of the femoral tunnel in ACL reconstruction: a computed tomography analysis

INTRODUCTION

The success of ACL reconstruction is predicated on a variety of factors. Tunnel placement plays one of the most significant roles in achieving knee kinematics and function. The purposes of this study were to compare femoral tunnel position, angle, length and posterior wall blow-out after ACL reconstruction with hamstring tendons autograft through either a farmedial portal or an anteromedial portal technique.

MATERIALS AND METHODS

We evaluated 36 patients who underwent ACL reconstruction between January 2014 and July 2014 in our institute, in a prospective, randomised cohort study. All the surgical procedures were performed by a sports fellowship-trained orthopaedic surgeon with experience in both portal reaming. The operated knees were evaluated with 0.5 mm fine CT scans of 3-D CT between days 3 and 5 postoperatively.

RESULTS

According to the 3-D CT measurements, the mean femoral tunnel length was significantly longer (p < 0.05) in the FAM group compared with the AM group. The femoral bone tunnel length averaged 34.2 ± 3.6 mm versus 36.6 ± 3.0 mm (p = 0.042) in AM and the FAM groups, respectively. The femoral tunnel position, as evaluated with use of the quadrant method, was more anterior in the FAM transportal technique group, and the difference between the two groups was significant (p < 0.05).

CONCLUSION

FAM tranportal drilling of the femoral tunnel creates longer and anterior femoral tunnels with regard to the AM portal drilling techniques. Additional studies with clinical outcomes are required for the clinical relevance of these techniques and to show which one is superior.

LEVEL OF EVIDENCE

Level I, prospective randomised comparative cohort study.

3D computer tomography for measurement of femoral position in acl reconstruction

Objective:

To validate intra- and inter-class correlation coefficients of a transparent 3D-TC protocol and investigate relationships between different axial rotations.

Methods:

Twenty unilateral knee TCs (iSite - Philips) were evaluated by means of a transparent 3D-TC OsiriX Imaging Software (v.3.9.4), 3D MPR protocol. Mathematical model of femoral tunnel projections acquired on vertical and horizontal rotations from -20 to +20 degrees. Height (h'/H) and length (t'/T) of tunnel projections have been analyzed by the Bernard and Hertel's method.

Statistics:

power of study=80%, ICC, ANOVA, p<0.05 (SPSS-19). Results: Transparent 3D-TC showed high reliability of both intra-observer (h'/H=0.941; t'/T=0.928, p<0.001) and inter-observer (h'/H=0.921; t'/T=0.890, p<0.001) ICC. ACL Length (t'/T) and Height (h'/H) projections were statistically different on vertical and horizontal rotations: p=0.01 and p<0.001, respectively.

Conclusion:

This new transparent 3D-TC protocol is an accurate and reproducible method that can be applied for ACL femoral tunnel or footprint measurement with high ICC reliability. Level of Evidence II, Descriptive Laboratory Study.

Skeletal imaging following reconstruction of the posterior cruciate ligament: in vivo comparison of fluoroscopy, radiography, and computed tomography

OBJECTIVE

Intra- and postoperative validation of anatomic footprint replication in posterior cruciate ligament (PCL) reconstruction can be conducted using fluoroscopy, radiography, or computed tomography (CT) scans. However, effectiveness and exposure to radiation of these imaging modalities are unknown. The objective of this study was to evaluate the comparative effectiveness of fluoroscopy, radiography, and CT in detecting femoral and tibial tunnel positions following an all-inside reconstruction of the PCL ligament in vivo. The study design was a retrospective case series.

MATERIALS AND METHODS

Intraoperative fluoroscopic images, postoperative radiographs, and CT scans were obtained in 50 consecutive patients following single-bundle PCL reconstruction. The centers of the tibial and femoral tunnel apertures were identified and correlated to measurement grid systems. The results of fluoroscopic, radiographic, and CT measurements were compared to each other and accumulated radiation dosages were calculated.

RESULTS

Comparing the imaging groups, no statistically significant difference could be detected for the reference of the femoral tunnel to the intercondylar depth and height, for the reference of the tibial tunnel to the mediolateral diameter of the tibial plateau and for the superoinferior distance of the tibial tunnel entry to the tibial plateau and to the former physis line. Effective doses resulting from fluoroscopic, radiographic, and CT exposure averaged 2.9 mSv, standard deviation (±SD) 4.1 mSv, to 1.3 ± 0.8 mSv and to 3.6 ± 1.0 mSv, respectively.

CONCLUSIONS

Fluoroscopy, radiography, and CT yield approximately equal effectiveness in detecting parameters used for quality validation intra- and postoperatively. An accumulating exposure to radiation must be considered.

Clinical outcome of anatomic double-bundle ACL reconstruction and 3D CT model-based validation of femoral socket aperture position

PURPOSE

The purpose of this study was to evaluate the clinical results of anatomic double-bundle (DB) anterior cruciate ligament (ACL) reconstruction in which anatomic position of femoral socket apertures was validated using three-dimensional (3D) computed tomography (CT) modelling.

METHODS

Anatomic DB ACL reconstructions with hamstring autografts were performed in 34 patients. Two femoral sockets were created through a far anteromedial (AM) portal behind the lateral intercondylar ridge with the assistance of intraoperative 3D fluoroscopic navigation. Femoral tunnel aperture positioning was investigated postoperatively using 3D CT images in all patients. Clinical results were also evaluated subjectively and objectively at least up to 2 years.

RESULTS

Measurement of the AM and the posterolateral (PL) femoral socket locations on the 3D CT images using the quadrant method showed that the centre of the AM socket aperture was located at a depth of 21.0 ± 4.1% and a height of 30.5 ± 9.3% and that of the PL socket aperture was located at a depth of 31.3 ± 5.8% and a height of 57.2 ± 7.7%. The femoral socket locations were considered as anatomic in accordance with previous cadaveric studies examining the positions of ACL femoral insertion site. Subjectively, the mean Lysholm score was 96.9 ± 4.0 points. According to IKDC final objective scores, 26 knees (76%) were objectively graded as normal, 8 (24%) as nearly normal, and 0 (0%) as abnormal or severely abnormal. Postoperative side-to-side anterior translation measured with a KT-2000 arthrometer averaged 0.7 ± 1.2 mm.

CONCLUSIONS

DB ACL reconstructions in which femoral socket apertures were validated anatomically using 3D CT provided satisfactory short-term results.

LEVEL OF EVIDENCE

Case series, Level IV.

Knee rotation influences the femoral tunnel angle measurement after anterior cruciate ligament reconstruction: a 3-dimensional computed tomography model study

PURPOSE

Femoral tunnel angle (FTA) has been proposed as a metric for evaluating whether ACL reconstruction was performed anatomically. In clinic, radiographic images are typically acquired with an uncertain amount of internal/external knee rotation. The extent to which knee rotation will influence FTA measurement is unclear. Furthermore, differences in FTA measurement between the two common positions (0° and 45° knee flexion) have not been established. The purpose of this study was to investigate the influence of knee rotation on FTA measurement after ACL reconstruction.

METHODS

Knee CT data from 16 subjects were segmented to produce 3D bone models. Central axes of tunnels were identified. The 0° and 45° flexion angles were simulated. Knee internal/external rotations were simulated in a range of ± 20°. FTA was defined as the angle between the tunnel axis and femoral shaft axis, orthogonally projected into the coronal plane.

RESULTS

Femoral tunnel angle was positively/negatively correlated with knee rotation angle at 0°/45° knee flexion. At 0° knee flexion, FTA for anterio-medial (AM) tunnels was significantly decreased at 20° of external knee rotation. At 45° knee flexion, more than 16° external or 19° internal rotation significantly altered FTA measurements for single-bundle tunnels; smaller rotations (± 9° for AM, ± 5° for PL) created significant errors in FTA measurements after double-bundle reconstruction.

CONCLUSION

Femoral tunnel angle measurements were correlated with knee rotation. Relatively small imaging malalignment introduced significant errors with knee flexed 45°. This study supports using the 0° flexion position for knee radiographs to reduce errors in FTA measurement due to knee internal/external rotation.

Eccentric femoral tunnel widening in anatomic anterior cruciate ligament reconstruction

PURPOSE

The purpose of this study was to retrospectively evaluate femoral tunnel widening (TW) and migration of the femoral tunnel aperture after anatomic anterior cruciate ligament (ACL) reconstructions with hamstring grafts and bone-patellar tendon-bone (BPTB) grafts.

METHODS

Of the 105 consecutive patients who underwent ACL reconstruction, the 52 patients who underwent isolated ACL reconstruction and in whom tunnel measurement could be obtained by computed tomography were included in this study. In 26 patients, double-bundle reconstruction (DBR) of the ACL using hamstring tendons was performed. These patients were compared with 26 patients in whom rectangular tunnel ACL reconstruction using BPTB grafts (BPTBR) was performed. Femoral tunnel aperture positioning and TW were investigated postoperatively using 3-dimensional computed tomographic images, which were performed a week and a year after surgery in all patients.

RESULTS

In DBR, the average diameter of the anteromedial (AM) femoral tunnel increased by 34.0% in the horizontal direction and 28.2% in the vertical direction, whereas that of the posterolateral (PL) femoral tunnel increased by 58.2% and 73.4%, respectively, at 1 year after surgery compared with 1 week after surgery. The percentage TW value of the PL tunnel was significantly greater than that of the AM tunnel. In BPTBR, the average diameter increased by 22.0% and 17.1%, respectively. The percentage TW value of the PL tunnel in DBR was significantly greater than that of the femoral tunnel in BPTBR. Each tunnel aperture migrated distally ("shallow") in the horizontal direction and high in the vertical direction. AM and PL tunnel apertures in DBR migrated in the vertical direction significantly more than they did in BPTBR. No significant differences between the 2 groups were found in clinical outcomes.

CONCLUSIONS

The femoral PL tunnel aperture in DBR showed significantly more widening than did the AM tunnel aperture in DBR and the femoral tunnel aperture in BPTBR. Also, greater migration of the femoral tunnel aperture in the vertical direction because of TW was observed in DBR than in BPTBR.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

Low inter- and intraobserver variability allows for reliable tunnel measurement in ACL reconstruction using the quadrant method

INTRODUCTION

Correct anatomic tunnel positions are essential in anterior cruciate ligament (ACL) reconstruction. To establish recommendations for tunnel positioning based on anatomical findings and to compare tunnel positions with clinical results, different radiological measurement methods as the quadrant method exist. Comparing the data of different observers requires the validation of the reliability of measurement methods. The purpose of this study therefore was to determine the reliability of the quadrant method to measure tunnel positions in ACL reconstruction. The hypothesis was, that the quadrant method shows a low inter- and intraobserver variability.

MATERIALS AND METHODS

In a test/retest scenario 20 knee surgeons were asked to determine defined tunnel positions in five lateral radiographs applying the quadrant method. Rotation, angle deviation, height and depth of the quadrant as well as absolute and relative tunnel positions of each observation were measured along referenced scales. Mean sizes and angle deviations of the quadrants, tunnel positions and deviations between the test/retest positions were calculated as well as standard deviations and range.

RESULTS

Interobserver variability analyses, to plan as well as to determine tunnel positions in ACL reconstruction, showed a mean variability (SD) of <1 mm, with ranges of 2.5 mm for planning and 3.7 mm for determination of tunnel positions using the quadrant method. Intraobserver analysis showed mean variability with deviations of <1 mm and maximum standard deviations of 0.7 mm and ranges of up to 2.3 mm.

CONCLUSIONS

We confirmed the hypothesis that the quadrant method has a low inter- and intraobserver variability. Based on the presented validation data, the quadrant method can be recommended as reliable method to radiographically describe insertion areas of the ACL as well as to determine tunnel positions in ACL reconstruction intra and postoperatively.

In vivo three-dimensional imaging analysis of femoral and tibial tunnel locations in single and double bundle anterior cruciate ligament reconstructions

BACKGROUND

Anatomic footprint restoration of anterior cruciate ligament (ACL) is recommended during reconstruction surgery. The purpose of this study was to compare and analyze the femoral and tibial tunnel positions of transtibial single bundle (SB) and transportal double bundle (DB) ACL reconstruction using three-dimensional computed tomography (3D-CT).

METHODS

In this study, 26 patients who underwent transtibial SB ACL reconstruction and 27 patients with transportal DB ACL reconstruction using hamstring autograft. 3D-CTs were taken within 1 week after the operation. The obtained digital images were then imported into the commercial package Geomagic Studio v10.0. The femoral tunnel positions were evaluated using the quadrant method. The mean, standard deviation, standard error, minimum, maximum, and 95% confidence interval values were determined for each measurement.

RESULTS

The femoral tunnel for the SB technique was located 35.07% ± 5.33% in depth and 16.62% ± 4.99% in height. The anteromedial (AM) and posterolateral (PL) tunnel of DB technique was located 30.48% ± 5.02% in depth, 17.12% ± 5.84% in height and 34.76% ± 5.87% in depth, 45.55% ± 6.88% in height, respectively. The tibial tunnel with the SB technique was located 45.43% ± 4.81% from the anterior margin and 47.62% ± 2.51% from the medial tibial articular margin. The AM and PL tunnel of the DB technique was located 33.76% ± 7.83% from the anterior margin, 45.56% ± 2.71% from the medial tibial articular margin and 53.19% ± 3.74% from the anterior margin, 46.00% ± 2.48% from the medial tibial articular margin, respectively. The tibial tunnel position with the transtibial SB technique was located between the AM and PL tunnel positions formed with the transportal DB technique.

CONCLUSIONS

Using the 3D-CT measuring method, the location of the tibia tunnel was between the AM and PL footprints, but the center of the femoral tunnel was at more shallow position from the AM bundle footprint when ACL reconstruction was performed by the transtibial SB technique.

Location of the femoral tunnel aperture in single-bundle anterior cruciate ligament reconstruction: comparison of the transtibial, anteromedial portal, and outside-in techniques

BACKGROUND

Previous 3-dimensional computed tomography (3D CT) studies of knees after anterior cruciate ligament (ACL) reconstruction have compared femoral tunnel positions obtained using the transtibial and anteromedial drilling techniques. This study used postoperative in vivo 3D CT analysis to compare the locations of the femoral tunnel aperture among 3 drilling techniques used in ACL reconstruction: transtibial, anteromedial portal, and outside-in.

HYPOTHESIS

The use of the transtibial drilling technique might result in a less anatomically accurate femoral tunnel placement than the anteromedial portal and outside-in techniques.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Immediate postoperative in vivo 3D CT was used to assess the location of the femoral tunnel aperture in 153 patients who underwent single-bundle ACL reconstruction using the transtibial (n = 42), anteromedial portal (n = 73), or outside-in (n = 38) techniques. Femoral tunnel positions were measured by an anatomic coordinate axis method in the low-to-high and deep-to-shallow directions of the distal femur at 90° of knee flexion.

RESULTS

The low-to-high femoral tunnel positions were significantly higher in the transtibial group than in the anteromedial portal (P < .001) and outside-in (P < .001) groups. There were no differences among the 3 groups in the deep-to-shallow femoral tunnel positions (P = .773).

CONCLUSION

The transtibial technique of anatomic reconstruction resulted in more highly positioned femoral tunnels in the low-to-high direction than did the anteromedial portal and outside-in techniques. However, no significant differences in the femoral tunnel location were observed in the deep-to-shallow direction.

Radiological evaluation for conflict of the femoral tunnel entrance area prior to anterior cruciate ligament revision surgery

PURPOSE

Anterior cruciate ligament (ACL) revision surgery is a demanding procedure and requires meticulous pre-operative clinical and radiological assessment. In clinical practice the position of the femoral tunnel is identified mainly using plain radiographs (XR). Two-dimensional computed tomography (2D-CT) and magnetic resonance imaging (MRI) are not yet routine imaging methods and are only performed in specific clinical indications or in the scientific setting. Several measurement methods describe the femoral tunnel after ACL reconstruction and indicate 'ideal or wrong' placement to the surgeon. The aim of this study is to provide a reliable measurement method to predict potential conflict between the pre-existing and the planned femoral tunnel entrance area (FTEA).

METHODS

Ten patients with primary ACL reconstruction served as a reference group to describe our desired FTEA. Their femoral tunnel positioning was measured on XR and 2D-CT according to published measurement methods. These results were compared to the FTEA measured with a new technique on 3-dimensionally reconstructed CT-images (3D-CT) based on intra-operative landmarks. Twenty patients requiring ACL revision surgery underwent identical radiological examination. The mean values of the reference group were compared to each measurement of the patients requiring revision surgery.

RESULTS

3D-CT measurements found potential conflicts in nine out of 20 patients, which all proved to be true during arthroscopic revision surgery. Only one of these patients was identified in all XR and 2D-CT measurements. In 12 out of all 30 patients some measurements on XR or 2D-CT could not be recorded.

CONCLUSION

3D-CT reconstruction shows the most accuracy in depicting conflict of the pre-existing and desired femoral tunnel prior to ACL revision surgery. The desired FTEA must be defined for each surgeon and his individual technique. In contrast, precision of conventional measurement techniques on XR and 2D-CT is low and does not qualify for this purpose.

Radiographic findings in revision anterior cruciate ligament reconstructions from the Mars cohort

The Multicenter ACL (anterior cruciate ligament) Revision Study (MARS) group was developed to investigate revision ACL reconstruction outcomes. An important part of this is obtaining and reviewing radiographic studies. The goal for this radiographic analysis is to establish radiographic findings for a large revision ACL cohort to allow comparison with future studies. The study was designed as a cohort study. Various established radiographic parameters were measured by three readers. These included sagittal and coronal femoral and tibial tunnel position, joint space narrowing, and leg alignment. Inter- and intraobserver comparisons were performed. Femoral sagittal position demonstrated 42% were more than 40% anterior to the posterior cortex. On the sagittal tibia tunnel position, 49% demonstrated some impingement on full-extension lateral radiographs. Limb alignment averaged 43% medial to the medial edge of the tibial plateau. On the Rosenberg view (45-degree flexion view), the minimum joint space in the medial compartment averaged 106% of the opposite knee, but it ranged down to a minimum of 4.6%. Lateral compartment narrowing at its minimum on the Rosenberg view averaged 91.2% of the opposite knee, but it ranged down to a minimum of 0.0%. On the coronal view, verticality as measured by the angle from the center of the tibial tunnel aperture to the center of the femoral tunnel aperture measured 15.8 degree ± 6.9% from vertical. This study represents the radiographic findings in the largest revision ACL reconstruction series ever assembled. Findings were generally consistent with those previously demonstrated in the literature.

Variability in ACL tunnel placement: observational clinical study of surgeon ACL tunnel variability

BACKGROUND

Multicenter and multisurgeon cohort studies on anterior cruciate ligament (ACL) reconstruction are becoming more common. Minimal information exists on intersurgeon and intrasurgeon variability in ACL tunnel placement. Purpose/

HYPOTHESIS

The purpose of this study was to analyze intersurgeon and intrasurgeon variability in ACL tunnel placement in a series of The Multicenter Orthopaedic Outcomes Network (MOON) ACL reconstruction patients and in a clinical cohort of ACL reconstruction patients. The hypothesis was that there would be minimal variability between surgeons in ACL tunnel placement.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

Seventy-eight patients who underwent ACL reconstruction by 8 surgeons had postoperative imaging with computed tomography, and ACL tunnel location and angulation were analyzed using 3-dimensional surface processing and measurement. Intersurgeon and intrasurgeon variability in ACL tunnel placement was analyzed.

RESULTS

For intersurgeon variability, the range in mean ACL femoral tunnel depth between surgeons was 22%. For femoral tunnel height, there was a 19% range. Tibial tunnel location from anterior to posterior on the plateau had a 16% range in mean results. There was only a small range of 4% for mean tibial tunnel location from the medial to lateral dimension. For intrasurgeon variability, femoral tunnel depth demonstrated the largest ranges, and tibial tunnel location from medial to lateral on the plateau demonstrated the least variability. Overall, surgeons were relatively consistent within their own cases. Using applied measurement criteria, 85% of femoral tunnels and 90% of tibial tunnels fell within applied literature-based guidelines. Ninety-one percent of the axes of the femoral tunnels fell within the boundaries of the femoral footprint.

CONCLUSION

The data demonstrate that surgeons performing ACL reconstructions are relatively consistent between each other. There is, however, variability of average tunnel placement up to 22% of mean condylar depth, likely reflecting the difference in individual surgeons' preferred tunnel locations. Individual surgeons are relatively consistent in their cases of ACL tunnels.

Transtibial versus low anteromedial portal drilling for anterior cruciate ligament reconstruction: a radiographic study of femoral tunnel position

PURPOSE

The purpose of this study is to compare femoral tunnel positions after ACL reconstruction by the transtibial (TT) approach versus the low anteromedial approach using radiographs from a single surgeon.

METHODS

The standard postoperative knee radiographs of 50 patients with an ACL reconstruction were studied. Two groups were determined according to the technique used. The low anteromedial portal group and the transtibial portal group. The femoral bone tunnel was identified radiographically, and its position determined in the lateral and A-P view. Coronal and sagittal obliquity of the tunnel was measured and compared among both groups.

RESULTS

In the sagittal plane, femoral bone tunnels averaged 54° ± 6° for the TT technique and 59° ± 12° (p = 0.07) for the low anteromedial portal technique. In the coronal plane, the bone tunnels drilled through the low anteromedial portal showed a significantly more oblique femoral tunnel position (50° ± 6°) compared to TT drilling (58° ± 9°), p ≤ 0.05.

CONCLUSION

Drilling the femoral tunnel through the low anteromedial portal resulted in a more oblique femoral tunnel position compared to the TT technique. Clinically, the low anteromedial portal may allow to better restore the anatomic orientation of the ACL.

Reliability of tunnel measurements and the quadrant method using fluoroscopic radiographs after anterior cruciate ligament reconstruction

BACKGROUND

Anterior cruciate ligament (ACL) reconstruction tunnel placement is often evaluated by radiographs. This study examines the interobserver reliability of various radiographic measurements of ACL tunnels.

HYPOTHESIS

When ideal radiographic views are obtained, the interobserver reliability of the measurements among experienced surgeons would be good to excellent.

STUDY DESIGN

Descriptive laboratory study.

METHODS

Tunnels for single-bundle ACL reconstruction were drilled and filled with metal interference screws or a tibial reamer on 73 cadaveric knees. Ideal fluoroscopic radiographs were obtained. Three independent reviewers performed 18 measurements including a modification of the grid method. For the grid method analysis, reviewers fit a 16 × 12 grid to the lateral knee radiograph, and the center of the femoral tunnel was marked. Interobserver reliability of the measurements was performed using intraclass correlation coefficients (ICCs). A precision grouping analysis was performed for the grid measurements to calculate the mean radius and standard deviation grouping distances.

RESULTS

The ICCs were excellent (>.75) for the tibial tunnel angles and tunnel measurements, the clock face measurement, and the Aglietti et al and Jonsson et al measurements. The ICCs were good (.4-.75) for an estimation of graft impingement, Harner et al measurements, and notch height. The mean radius for grid measurements was 0.6 ± 0.4 units (range, 0-2.36 units), with each unit being 1 box in the 16 × 12 grid. When a circle was constructed with a 1.3-unit radius, 95% of the 3 surgeons' measurements would be included in the area of that circle.

CONCLUSION

Reliability of ACL tunnel measurements was good to excellent under ideal circumstances for the majority of measurements. The modified grid method demonstrated very acceptable reliability.

CLINICAL RELEVANCE

Measurements with good to excellent reliability can be used to evaluate ACL tunnel placement when ideal radiographic views are obtained.

Revision anterior cruciate ligament reconstruction: an update

With the rising number of anterior cruciate ligament (ACL) reconstructions performed, revision ACL reconstruction is increasingly common nowadays. A broad variety of primary and revision ACL reconstruction techniques have been described in the literature. Recurrent instability after primary ACL surgery is often due to non-anatomical ACL graft reconstruction and altered biomechanics. Anatomical reconstruction must be the primary goal of this challenging revision procedure. Recently, revision ACL reconstruction has been described using double bundle hamstring graft. Successful revision ACL reconstruction requires an exact understanding of the causes of failure and technical or diagnostic errors. The purpose of this article is to review the causes of failure, preoperative evaluation, graft selection and types of fixation, tunnel placement, various types of surgical techniques and clinical outcome of revision ACL reconstruction.

Tunnel position following posterior cruciate ligament reconstruction: an in vivo computed tomography analysis

The success of posterior cruciate ligament (PCL) reconstruction is dependent on appropriate tunnel placement. Computed tomography (CT) provides detailed images of intra-articular osseous anatomy. The objective of this study was to analyze by CT the position of femoral and tibial tunnels relative to intra-operative goals following arthroscopic-assisted PCL reconstruction. Nineteen patients who underwent single-bundle PCL reconstruction were evaluated 16 months post-operatively. Each underwent a CT scan and tunnel locations were identified in the coronal, sagittal, and axial planes. The coronal plane tibial tunnel location was within 5mm of the intra-operative goal (48% of the total tibial plateau width from the medial border of the plateau) in 16 patients (84%). The sagittal plane tibial tunnel location was within 5mm of the intra-operative goal (the middle of the posterior half of the retrospinal surface) in 14 patients (74%). In the sagittal plane, the femoral tunnel location was within 5mm of the intra-operative goal (10mm from in the distal articular margin of the medial femoral condyle) in 15 patients (79%). In the notch, the femoral tunnel was between 10:30 and 11:30 for left knees or between 12:30 and 1:30 for right knees (the intra-operative goal was 11 o'clock for left knees and 1 o'clock for right knees) in 18 patients (95%). Arthroscopic PCL reconstruction results in tunnel positions near intra-operative goals. Further work is necessary to define CT-specific criteria for the assessment of PCL tunnel position.