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

Indicaciones y planificación de la revisión en dos tiempos de la cirugía del ligamento cruzado anterior: revisión narrativa

El aumento en las cirugías de reconstrucción del ligamento cruzado anterior (RLCA) ha generado un incremento proporcional en las revisiones quirúrgicas. Estadísticas canadienses estiman aproximadamente 13 000 revisiones anuales, mientras que en EE. UU. se reporta una incidencia entre el 4.1 y el 13.3 % de todas las RLCA.El éxito de una cirugía de revisión depende de un enfoque sistemático que permita identificar la causa de la falla, como una re-rotura o inestabilidad persistente, y planificar el procedimiento definitivo. Si bien la mayoría de estas revisiones se realizan en un solo tiempo, entre el 8 y el 9 % requieren un abordaje en dos tiempos. Esta decisión depende de factores como la calidad ósea, el tamaño y la posición de los túneles, el método de fijación previo y la presencia de lesiones asociadas.La principal indicación para una revisión en dos tiempos es la osteólisis con túneles mayores a 14 mm o el riesgo de convergencia entre los túneles primarios y de revisión. En este artículo se presenta una revisión narrativa sobre las indicaciones y la planificación quirúrgica de las revisiones del LCA en dos tiempos.En conclusión, existe evidencia limitada, y en general de corto plazo, sobre los resultados de la reconstrucción del LCA en revisiones de dos etapas. A pesar de estas suelen realizarse en casos más complejos, los resultados reportados mostraron resultados clínicos comparables. Nivel de Evidencia: V

One-stage revision anterior cruciate ligament reconstruction: Preoperative evaluation, planning and surgical techniques. A review of current concepts

The increased rate of anterior cruciate ligament (ACL) tears has led to a greater number of revisions. Revision surgery can be performed in one or two stages. Single-stage revision ACL reconstruction (ssRACLR) may be performed when prior tunnels can be re-used or bypassed whereas a two-stage procedure is indicated when bone grafting of dilated tunnels prior to revision is necessary. While both approaches have shown similar functional outcomes and failure risk, ssRACLR is preferred, when possible, to avoid the increased morbidity, inconvenience and cost associated with two-stage RACLR. In adequately planning for RACLR, a surgeon should investigate the mechanism and timing of injury as well as the previous graft selection, associated pathology and the tunnel placement and size. It is especially important to obtain radiographs and three-dimensional imaging including magnetic resonance imaging (MRI) and computed tomography (CT), which allow the surgeon to accurately evaluate the entire tunnel architecture to determine surgical staging. Following a detailed assessment of the pathoanatomy, the surgeon may determine graft and hardware type, tunnel placement and utilization of lateral extra-articular tenodesis (LET) and other procedures. In our experience, ssRACLR can be carried out for over 90% of revision cases with creative pre-operative planning using autograft with bone plug(s), divergent tunnel creation on the femur (when necessary) and convergent tunnel creation on the tibia (when appropriate) and suspensory or interference fixation as needed. In revision scenarios, we believe that autografts with bone plugs provide the best opportunity for graft healing and incorporation and that LET can be a useful adjunct to reduce re-tear rates. The purpose of this review is to report on the preoperative considerations and surgical techniques for performing ssRACLR, as well as the outcomes.

Level of Evidence

Level V expert opinion.

No Difference in Bone Tunnel Enlargement and Clinical Outcome between Cortical Suspension and Hybrid Femoral Fixation in Hamstring Anterior Cruciate Ligament Reconstruction

OBJECTIVE

The best method for femoral fixation in anterior cruciate ligament reconstruction (ACLR) remains controversial. The study assesses the bone tunnel enlargement and clinical outcome in hamstring ACLR using cortical suspension or hybrid (cortical suspension and compression) femoral fixation.

METHODS

From January 2010 to December 2021, 102 patients who underwent quadruple hamstring ACLR using cortical suspension (39 patients) or hybrid (63 patients) fixation on the femoral side were retrospectively analyzed. Clinical evaluation was conducted using the international knee documentation committee score, the Lysholm score, the Tegner activity level scale, the knee injury and osteoarthritis outcome score (quality of life score), the Lachman test, and the side-to-side difference by the KT-1000 arthrometer. The complications after the surgery were also evaluated. These data were compared at baseline and last follow-up. The diameters of the femoral tunnel were calculated at three sites: the width of the entrance of the femoral tunnel, 1 cm proximal to the entrance of the femoral tunnel and the largest diameter of the femoral tunnel on magnetic resonance imaging (MRI) coronal images. Bone tunnel widening data were contrasted between MRI images conducted at least 2 years and within 2 weeks after surgery. The morphology of bone tunnel enlargement was also observed and recorded. The categorical parameters were analyzed using the χ2-test and Fisher's exact test. The continuous variables conforming to a normal distribution were analyzed using Student's t-test, and the Mann-Whitney U-test was undertaken between the two groups without normal distribution.

RESULTS

Both cortical suspension and hybrid femoral fixation in quadruple hamstring ACLR achieved significantly improved patient-reported outcome scores and knee stability compared to preoperative data. However, no significant differences were found between these two methods in clinical evaluations, postoperative complications, and patient-reported outcome scores. Although the mean diameter of the enlarged bone tunnel was lowered by an additional bioabsorbable interference screw fixation near the joint line, a statistically insignificant difference was found between the hybrid and cortical suspension fixation on the femoral side. There was no statistical difference in the distribution of enlarged bone tunnel morphology between groups.

CONCLUSIONS

No significant difference was found in the bone tunnel enlargement and clinical outcome between cortical suspension and hybrid femoral fixation in ACLR using hamstring autograft.

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.

Usefulness of 3-Dimensional Computed Tomography Assessment of Femoral Tunnel after Anterior Cruciate Ligament Reconstruction

Positioning of the femoral tunnel during anterior cruciate ligament (ACL) reconstruction is the most crucial factor for successful procedure. Owing to the inter-individual variability in the intra-articular anatomy, it can be challenging to obtain precise tunnel placement and ensure consistent results. Currently, the three-dimensional (3D) reconstruction of computed tomography (CT) scans is considered the best method for determining whether femoral tunnels are positioned correctly. Postoperative 3D-CT feedback can improve the accuracy of femoral tunnel placement. Precise tunnel formation obtained through feedback has a positive effect on graft maturation, graft failure, and clinical outcomes after surgery. However, even if femoral tunnel placement on 3D CT is appropriate, we should recognize that acute graft bending negatively affects surgical results. This review aimed to discuss the implementation of 3D-CT evaluation for predicting postoperative outcomes following ACL re-construction. Reviewing research that has performed 3D CT evaluations after ACL reconstruction can provide clinically significant evidence of the formation of ideal tunnels following anatomic ACL reconstruction.

Clinical outcomes and return to sport after single-stage revision anterior cruciate ligament reconstruction by bone-patellar tendon autograft combined with lateral extra-articular tenodesis

PURPOSE

The anterior cruciate ligament reconstruction (ACLR) failure rate continues to increase. Involvement of a young population with a desire to return to sport, explains the increased need for ACLR (revACLR) revision. The aim of this study was to evaluate clinical outcome, complications, failure rate and return to sport of a single-stage revACLR using bone patellar tendon-bone (BTBT) combined with lateral extra-articular tenodesis (LET).

MATERIAL AND METHODS

A retrospective analysis was performed on 36 patients who underwent revACLR. Knee stability was assessed by Lachman and Pivot shift test. Objective anterior laxity was determined by KT-2000 arthrometer. The IKDC subjective, Lysholm, ACL-RSI Scores, level of sport activity and Forgotten Joint Score-12 were recorded.

RESULTS

Of 36 patients, we collected data from 17 who underwent single-stage revACLR with autologous BTBT combined with LET, performed using an extra-articular MacIntosh procedure as modified by Arnold-Coker. The side-to-side difference in Lachman test and Pivot shift test significantly improved postoperatively. The subjective IKDC, Lysholm and ACL-RSI significantly improved from 71.4 ± 9.03 to 92 ± 6.9, from 58.3 ± 19.3 to 66.8 ± 27.7 and from 50.4 ± 12.2 to 68.6 ± 24.5, respectively during the post-operative follow-up. Ten patients (58.8%) returned to their desired level of sport. One patient was considered a failure because of the postoperative laxity.

CONCLUSION

Single-stage revACLR with BPTB combined with LET is a safe procedure that shows good objective and subjective outcomes, and a high rate of return to the same level of sport. Reducing rotational instability and strain on intra-articular reconstructed structures results in a low rate of complications and failure.

Tunnel Management in Revision Anterior Cruciate Ligament Reconstruction: Current Concepts

Bone tunnel-related complications are frequently encountered during revision anterior cruciate ligament reconstruction (ACLR). Issues with tunnel positioning, enlargement, containment, and hardware interference may complicate surgery and compromise outcomes. As a result, several strategies have emerged to address these issues and optimize results. However, a systematic, unified approach to tunnel pathology in revision ACLR is lacking. The purpose of this review is to highlight the current state of the literature on bone tunnel complications and, although extensive literature on the subject is lacking, present an updated approach to the evaluation and management of tunnel-related issues in revision ACLR.

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.

Preoperative Determination of the Size of the Semitendinosus and Gracilis Tendon by Multidetector Row CT Scanner for Anterior Cruciate Ligament Reconstruction

Accurately measuring the length and diameter of the hamstring tendon autograft preoperatively is important for planning anterior cruciate ligament (ACL) reconstructive surgery. The purpose of this study was to assess the reliability of three-dimensional computed tomography (3D CT) scanning technique to produce the actual measurement of the gracilis and semitendinosus (GT and ST, respectively) tendon grafts' length and diameter for surgery. Ninety patients were scheduled for ACL reconstruction with hamstring autograft. Before the surgery, patients were examined under the multidetector row CT scanner and the ST and GT tendons were qualitatively measured by a volume-rendering technique. The length of ST and GT was measured with 3D CT compared with the length of the harvested ST and GT. The cross-sectional area (CSA) of ST and GT measured with 3D CT compared with the ST and GT graft diameter. Tendon size measured preoperatively and during surgery were statistically compared and correlated. The GT tendons length and cross-sectional area measured during surgery was both shorter and smaller compared with the ST tendon. GT and ST tendon length were correlated to patients' body index such as the height and weight (p < 0.05). However, the correlation levels were low to medium (r = 0.23-0.49). There was strong correlation between the lengths of GT (r = 0.76; p < 0.001) and ST (r = 0.87; p < 0.001) measured with the 3D CT and tendon length at surgery. There was a moderate correlation between graft diameter measured at surgery and 3D CT cross-sectional area (r = 0.31; p < 0.05). A multidetector row CT scanner can determine the ST and GT tendons' length and diameter. These measurements can be used for preoperative planning to help determine the surgical method and counsel patients on appropriate graft choices prior to surgery.

Posttreatment Imaging of the Knee: Cruciate Ligaments and Menisci

Cruciate ligament reconstruction and meniscal surgery are frequently performed for restoration of knee joint stability and function after cruciate ligament and meniscus injuries, and they contribute to the prevention of secondary osteoarthritis. In cruciate ligaments, the most common procedure is anterior cruciate ligament (ACL) reconstruction. Meniscal surgery most frequently consists of partial meniscectomy and suture repair, rarely of a meniscus transplant. In patients with symptoms following surgery, imaging reevaluation for a suspected intra-articular source of symptoms is indicated and mainly consists of radiography and magnetic resonance imaging. For proper imaging assessment of cruciate ligament grafts and the postoperative meniscus, it is crucial to understand the surgical techniques applied, to be familiar with normal posttreatment imaging findings, and to be aware of patterns and specific findings of recurrent lesions and typical complications. This article presents an updated review of the techniques and the imaging of cruciate ligament reconstruction and meniscus surgery, recurrent lesions, treatment failure, and potential complications.

Beighton Score, Tibial Slope, Tibial Subluxation, Quadriceps Circumference Difference, and Family History Are Risk Factors for Anterior Cruciate Ligament Graft Failure: A Retrospective Comparison of Primary and Revision Anterior Cruciate Ligament Reconstructions

PURPOSE

To assess patient history, physical examination findings, magnetic resonance imaging (MRI) and 3-dimensional computed tomographic (3D CT) measurements of those with anterior cruciate ligament (ACL) graft failure compared with primary ACL tear patients to better discern risk factors for ACL graft failure.

METHODS

We performed a retrospective review comparing patients who underwent revision ACL reconstruction (ACLR) with a primary ACLR group with minimum 1-year follow-up. Preoperative history, examination, and imaging data were collected and compared. Measurements were made on MRI, plain radiographs, and 3D CT. Inclusion criteria were patients who underwent primary ACLR by a single surgeon at a single center with minimum 1-year follow-up or ACL graft failure with revision ACLR performed by the same surgeon.

RESULTS

A total of 109 primary ACLR patients, mean age 33.7 years (range 15 to 71), enrolled between July 2016 and July 2018 and 90 revision ACLR patients, mean age 32.9 years (range 16 to 65), were included. The revision ACLR group had increased Beighton score (4 versus 0; P < .001) and greater side-to-side differences in quadricep circumference (2 versus 0 cm; P < .001) compared with the primary ACLR group. A family history of ACL tear was significantly more likely in the revision group (47.8% versus 16.5%; P < .001). The revision group exhibited significantly increased lateral posterior tibial slope (7.9° versus 6.2°), anterolateral tibial subluxation (7.1 versus 4.9 mm), and anteromedial tibia subluxation (2.7 versus 0.5 mm; all P < .005). In the revision group, femoral tunnel malposition occurred in 66.7% in the deep-shallow position and 33.3% in the high-low position. The rate of tibial tunnel malposition was 9.7% from medial to lateral and 54.2% from anterior to posterior. Fifty-six patients (77.8%) had tunnel malposition in ≥2 positions. Allograft tissue was used for the index ACLR in 28% in the revision group compared with 14.7% in the primary group.

CONCLUSION

Beighton score, quadriceps circumference side-to-side difference, family history of ACL tear, lateral posterior tibial slope, anterolateral tibial subluxation, and anteromedial tibia subluxation were all significantly different between primary and revision ACLR groups. In addition, there was a high rate of tunnel malposition in the revision ACLR group.

Positioning of the Tibial Tunnel After Single-Bundle ACL Primary Reconstruction on 3D CT scans: A New Method

Purpose

To assess intra-articular tunnel aperture positioning after primary anterior cruciate ligament (ACL) reconstruction with either the reference standard method or the intercondylar area method in a single center using 3-dimensional (3D) computed tomography (CT) scans and to evaluate the intra-articular position of the tibial tunnel relative to the ACL footprint.

Methods

3D CT scans were performed after 120 single-bundle primary ACL reconstruction cases. The center of the tibial tunnel aperture and the center of the ACL footprint were referenced on axial views of the tibial plateau in the anteroposterior (AP) and mediolateral (ML) planes according to a centimetric grid system including the whole plateau (reference standard). This was compared with a grid system based on intercondylar area bony anatomy. The posterior aspect of intertubercular fossa, anterior aspect of the tibial plateau, medial intercondylar ridge, and crossing point between lateral intercondylar ridge and posterior margin were used as landmarks to define the grid.

Results

According to the reference standard method, the center of the tibial tunnel aperture was positioned 0.57 ± 2.62 mm more posterior and 0.67 ± 1.55 mm more medial than the center of the footprint. According to the intercondylar area method, the center of the tibial tunnel aperture was positioned 1.32 ± 2.74 mm more posterior and 0.66 ± 1.56 mm more medial than the center of the footprint. The position difference between the center of the tunnel aperture and the center of the footprint were statistically correlated for both grids, with r = –0.887, P < .001 for AP positioning and r = 0.615, P < .001 for ML positioning.

Conclusion

This intercondylar area method using arthroscopic landmarks can be used to assess tunnel placement on 3D CT scans after ACL reconstruction.

Level of Evidence

III, retrospective comparative study.

Intraoperative fluoroscopy shows better agreement and interchangeability in tibial tunnel location during single bundle anterior cruciate ligament reconstruction with postoperative three-dimensional computed tomography compared with an intraoperative image-free navigation system

BACKGROUND

Fluoroscopy and navigation systems provide an accurate and reproducible method of guiding anatomical tunnel positioning during anterior cruciate ligament reconstruction (ACLR). The aim was to evaluate the differences in tibial tunnel location assessed by both an intraoperative navigation system and fluoroscopy, validated using a one-week postoperative three-dimensional computed tomography (3DCT).

METHODS

The tibial tunnel location in a consecutive series of 35 patients who received a single-bundle ACLR was evaluated by intraoperative navigation system, fluoroscopic image and compared with postoperative 3DCT position. The location to the anterior-posterior (AP) and medial-lateral (ML) direction were compared between all three methods.

RESULTS

The tibial tunnel locations were 46.7 ± 4.5%, 44.5 ± 1.9%, and 43.6 ± 2.4% in ML direction, and 42.8 ± 7.6%, 37.9 ± 3.8%, and 37.9 ± 3.7% in AP direction using an intraoperative navigation system, fluoroscopic image and postoperative 3DCT, respectively. Significant differences between the navigation system and fluoroscopic image (ML, P = 0.001; AP, P = 0.006), and the navigation system and 3DCT (ML, P = 0.001; AP, P < 0.001) were seen. However, there was no significant difference between fluoroscopy and 3DCT (ML, P = 0.315; AP, P = 0.999). There was a significant lack of agreement for analyses measured using a navigation system and 3DCT. Fluoroscopy and 3DCT demonstrated an acceptable agreement (ML, r_pt = -0.21, P = 0.232; AP, r_pt = 0.04, P = 0.826).

CONCLUSIONS

A tibial tunnel location assessed by intraoperative fluoroscopy shows better agreement and interchangeability with one-week postoperative 3DCT validation during single-bundle ACLR compared with an intraoperative image-free navigation system.

Correlation between notch width index assessed via magnetic resonance imaging and risk of anterior cruciate ligament injury: an updated meta-analysis

PURPOSE

To analyze the correlation between notch width index (NWI) and/or femoral intercondylar notch width (NW) assessed by magnetic resonance imaging (MRI) and risk of anterior cruciate ligament (ACL) injury.

METHODS

We searched the PubMed, Embase, China National Knowledge Infrastructure and Wanfang databases for literature reporting a correlation between ACL injury and NWI and/or NW. Subgroup analyses were stratified by ethnicity, sex and control source. The weighted mean difference (WMD) and 95% confidence intervals (95% CIs) were calculated for the ACL injury cases and controls using random- or fixed-effects models. Begg's test and sensitivity analyses were applied to assess publication bias and stability of the results, respectively.

RESULTS

Twenty-eight eligible studies were finally enrolled. The NW was significantly narrowerin the ACL injury cases than in the control cases (pooled WMD, - 1.88 [95% CI, - 2.43 to - 1.32]). The results were similar when stratified by ethnicity and sex. Similarly, the NWI was lower in ACL injury cases than in the controls. Asian populations presented similar results when stratified by ethnicity, among the self-control group when stratified by control source, and among men when stratified by sex. No publication bias was identified; however, the sensitivity analysis suggested unstable results in the NWI subgroup analysis.

CONCLUSIONS

The current meta-analysis evidenced that the NW assessed via MRI was significantly smaller in ACL injury cases than in the controls. The NWI was lower in ACL injury cases among men. Prevention strategies for ACL injury could be applied for people with intercondylar notch stenosis.

Anatomical rectangular tunnels identified with the arthroscopic landmarks result in excellent outcomes in ACL reconstruction with a BTB graft

PURPOSE

To elucidate tunnel locations and clinical outcomes after anatomic rectangular tunnel (ART) anterior cruciate ligament reconstruction (ACLR) using a bone-patellar tendon-bone (BTB) graft.

METHODS

Sixty-one patients with a primary unilateral ACL injury were included. Tunnels were created inside the ACL attachment areas after carefully removing the ACL remnant and clearly identifying the bony landmarks. Using 3-dimensional computed tomography (3-D CT) images, the proportion of the tunnel apertures to the anatomical attachment areas was evaluated at 3 weeks. The clinical outcomes were evaluated at 2 years postoperatively.

RESULTS

Geographically, the 3-D CT evaluation showed the entire femoral tunnel aperture; at least 75% of the entire tibial tunnel aperture area was consistently located inside the anatomical attachment areas surrounded by the bony landmarks. In the International Knee Documentation Committee (IKDC) subjective assessment, all patients were classified as 'normal' or 'nearly normal'. The Lachman test and pivot-shift test were negative in 98.4% and 95.1% of patients, respectively. The mean side-to-side difference of the anterior laxity at the maximum manual force with a KT- 1000 Knee Arthrometer was 0.2 ± 0.9 mm, with 95.1% of patients ranging from - 1 to + 2 mm.

CONCLUSION

By identifying arthroscopic landmarks, the entire femoral tunnel aperture and at least 75% of the entire tibial tunnel aperture area were consistently located inside the anatomical attachment areas. With properly created tunnels inside the anatomical attachment areas, the ART ACLR using a BTB graft could provide satisfactory outcomes both subjectively and objectively in more than 95% of patients.

LEVEL OF EVIDENCE

Case series, Level IV.

Computed Tomography Assessment of Anatomic Graft Placement After ACL Reconstruction: A Comparative Study of Grid and Angle Measurements

Background:

The anatomic placement of anterior cruciate ligament (ACL) grafts is often assessed with postoperative imaging. In clinical practice, graft angles are measured to indicate anatomic placement on magnetic resonance imaging, whereas grid measurements are performed on computed tomography (CT). Recently, a study indicated that graft angle measurements could also be assessed on CT. No consensus has yet been reached on which measurement method is best suited to assess anatomic graft placement.

Purpose:

To compare the ability of grid measurements and angle measurements to identify anatomic versus nonanatomic tunnel placement on CT performed in patients undergoing ACL reconstruction.

Study Design:

Case series; Level of evidence, 4.

Methods:

A total of 100 knees undergoing primary reconstruction with a hamstring graft (HAM group), 91 undergoing reconstruction with a bone–patellar tendon–bone graft (BPTB group), and 117 undergoing revision ACL reconstruction (REV group) were assessed with CT. Grid measurements of the femoral and tibial tunnels and angle measurements of grafts were performed. Graft placement, rated as anatomic or nonanatomic, was assessed with both methods. Pearson chi-square, analysis of variance, Kruskal-Wallis, and weighted kappa tests were performed as appropriate.

Results:

The grid assessment classified 10% of the HAM group, 4% of the BPTB group, and 17% of the REV group as nonanatomic (P < .001). The angle assessment classified 37% of the HAM group, 54% of the BPTB group, and 47% of the REV group as nonanatomic. The weighted kappa between angle measurements and grid measurements was low in all groups (HAM: 0.009; BPTB: 0.065; REV: 0.041).

Conclusion:

The agreement between grid measurements and angle measurements was very low. The angle measurements seemed to overestimate nonanatomic tunnel placement. Grid measurements were better in identifying malpositioned grafts.

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.

Post-operative 3D CT feedback improves accuracy and precision in the learning curve of anatomic ACL femoral tunnel placement

PURPOSE

To evaluate the feedback from post-operative three-dimensional computed tomography (3D-CT) on femoral tunnel placement in the learning process, to obtain an anatomic anterior cruciate ligament (ACL) reconstruction.

METHODS

A series of 60 consecutive patients undergoing primary ACL reconstruction using autologous hamstrings single-bundle outside-in technique were prospectively included in the study. ACL reconstructions were performed by the same trainee-surgeon during his learning phase of anatomic ACL femoral tunnel placement. A CT scan with dedicated tunnel study was performed in all patients within 48 h after surgery. The data obtained from the CT scan were processed into a three-dimensional surface model, and a true medial view of the lateral femoral condyle was used for the femoral tunnel placement analysis. Two independent examiners analysed the tunnel placements. The centre of femoral tunnel was measured using a quadrant method as described by Bernard and Hertel. The coordinates measured were compared with anatomic coordinates values described in the literature [deep-to-shallow distance (X-axis) 28.5%; high-to-low distance (Y-axis) 35.2%]. Tunnel placement was evaluated in terms of accuracy and precision. After each ACL reconstruction, results were shown to the surgeon to receive an instant feedback in order to achieve accurate correction and improve tunnel placement for the next surgery. Complications and arthroscopic time were also recorded.

RESULTS

Results were divided into three consecutive series (1, 2, 3) of 20 patients each. A trend to placing femoral tunnel slightly shallow in deep-to-shallow distance and slightly high in high-to-low distance was observed in the first and the second series. A progressive improvement in tunnel position was recorded from the first to second series and from the second to the third series. Both accuracy (+52.4%) and precision (+55.7%) increased from the first to the third series (p < 0.001). Arthroscopic time decreased from a mean of 105 min in the first series to 57 min in the third series (p < 0.001). After 50 ACL reconstructions, a satisfactory anatomic femoral tunnel was reached.

CONCLUSION

Feedback from post-operative 3D-CT is effective in the learning process to improve accuracy and precision of femoral tunnel placement in order to obtain anatomic ACL reconstruction and helps to reduce also arthroscopic time and learning curve. For clinical relevance, trainee-surgeons should use feedback from post-operative 3DCT to learn anatomic ACL femoral tunnel placement and apply it appropriately.

LEVEL OF EVIDENCE

Consecutive case series, Level IV.

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.

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."

Anterior cruciate ligament reconstruction: MR imaging findings

More than two million people tear their anterior cruciate ligament (ACL) each year, and ACL reconstruction occupies a significant proportion of everyday orthopedic practice, being one of the most commonly performed sports medicine surgical procedures. Patients with postoperative symptoms are frequently imaged to monitor ligament grafts and to identify complications. Given the number of patients undergoing ACL reconstruction, knowledge of the potential complications of this surgery is essential for radiologists. This article provides a review of imaging of ACL reconstruction procedures and the potential complications specific to this surgery.

Relationship between bony tunnel and knee function in patients after patellar dislocation triple surgeries-a CT-based study

We aimed to assess the CT-based bony tunnel valuations and their correlation with knee function after patellar dislocation triple surgeries. A retrospective study was performed on 66 patients (70 knees) who underwent patellar dislocation triple surgeries. The surgery was MPFL reconstruction primarily, combined with lateral retinaculum release and tibial tubercle osteotomy. CT examinations were performed to determine the femoral tunnel position, along with the patellar and femoral tunnel width 3 days and more than 1 year after operation for follow-up. Functional evaluation based on Kujala and Lysholm scores was also implemented. We compared tunnel width of the first and last examinations and correlated femoral tunnel position of the last examination with knee function. At the last follow-up, femoral tunnel position in the anterior-posterior direction was moderately correlated with knee function. Femoral tunnel position in the proximal-distal direction was not associated with postoperative knee function. Patellar and femoral tunnel width increased significantly at the last follow-up. However, no significant functional difference was found between patients with and without femoral tunnel enlargement. Our results suggested that the tunnel malposition in anterior-posterior position based on CT was related to impaired knee function during the follow-ups.

Imaging the Anterior and Posterior Cruciate Ligaments

The anterior and posterior cruciate ligaments are important stabilizers of the knee joint function. Although they are both similar in their native appearance, they possess slightly different properties and complement each other's function. The imaging findings differ between the anterior and posterior cruciate ligaments. While MRI is the main imaging modality, radiographs and CT have a role in pre- and post-operative imaging. The aim of this review is to present pre-and post-operative imaging findings of injured cruciate ligaments. A special emphasis will be placed on the potential pitfalls in cruciate ligament imaging.