Tibial attachment area of the anterior cruciate ligament in the extended knee position. Anatomy and cryosections in vitro complemented by magnetic resonance arthrography in vivo

Estimation of footprints of the canine stifle ligaments using deformable shape templates of bones

Knowledge regarding the ligament footprints in the canine stifle is essential for biomechanical modeling of the joint and patient-specific surgical planning for anatomical ligament reconstruction. The present study aimed to establish and evaluate deformable shape templates (DSTs) of the femur and tibia with footprints of the cruciate and collateral ligaments embedded for the noninvasive estimation of ligament footprint positions. To this end, a data set of computed tomography (CT)-derived surface models of the femur and tibia were established and used to build statistical shape models (SSMs). The contours of the stifle ligaments were obtained from CT scans of 27 hindlimb specimens with radio-opaque markings on the ligament footprints. The DST, constructed by embedding averaged footprint contours into the SSM, was used to estimate subject-specific ligament footprints in a leave-one-out cross-validation framework. The DST predictions were compared with those derived from radio-opaque-marked footprints. The results showed that the averaged Euclidean distances between the estimated and reference footprint centroids were less than 1.2 mm for the cruciate ligaments and 2.0 mm for the collateral ligaments. The DST appeared to provide a feasible alternative approach for noninvasively estimating the footprints of the stifle ligaments in vivo.

Less Subsequent Revision Anterior Cruciate Ligament (ACL) Reconstruction Following Primary Bone-Patellar Tendon-Bone ACL Reconstruction with Suture Tape Augmentation-A Retrospective Comparative Therapeutic Trial With 5-Year Follow-up

PURPOSE

To investigate patient outcomes, including revision rate, following primary bone patellar-tendon bone autograft (BPTB) anterior cruciate ligament reconstruction (ACLR) with and without suture tape augmentation (STA) in a young and active cohort.

METHODS

All eligible patients who received primary BPTB ACLR with a minimum of 2-year follow-up were included in this retrospective cohort study. All patients receiving STA were augmented with the same device. Patients completed the following patient-reported outcome measures (PROMs): the visual analog scale, the Single Assessment Numeric Evaluation, the Knee Injury and Osteoarthritis Outcome Score subscales, and the Tegner activity scale. Anteroposterior knee laxity was assessed using a KT-1000 arthrometer preoperatively and 1-year postoperatively. Posterior tibial slope, femoral tunnel angle, and tibial tunnel placement were calculated for all patients. Subsequent surgical interventions and return to sport (RTS) were obtained from each patient.

RESULTS

One hundred fourteen patients (52 BPTB ACLR with STA, 62 traditional BPTB ACLR) with a mean patient age <19 years and a mean final follow-up of ≥5 years were included. Compared with the control group, the STA group demonstrated significantly less subsequent revision ACLR (0 vs. 5, P = .036). All PROMs and KT-1000 measurements improved at final follow-up (P < .001) and were comparable between groups. There were no differences seen in either posterior tibial slope or graft tunnel placement between groups. More than 85% of the patients were able to return to the sport that led to their injury at full capacity with no differences seen in RTS rate, time to RTS, or level of competition between groups.

CONCLUSIONS

Compared with traditional BPTB ACLR, additional STA appeared to safely and effectively lead to less subsequent revision ACLR while maintaining acceptable PROMs and objective joint laxity measurements in a young and active patient population.

LEVEL OF EVIDENCE

Level III, retrospective cohort study.

Can patient anthropometry predict the anterior cruciate ligament footprint dimensions? - An MRI-based observational study on north Indian population

Background

Anterior Cruciate Ligament (ACL) reconstruction is one of the most common surgeries being currently done. As we usher into the era of Individualized Anatomic Reconstruction, it is very important to understand the native anatomy of ACL. We aimed to assess the ACL footprint dimensions in our patients and correlate it with anthropometric variables, which can help in preoperative decision making.

Method

A total of 143 eligible patients with suspected ACL injury presented during the study period. Out of which 92 were included in the study. Data on patient's age, sex, height, weight and body mass index (BMI) was recorded. The length and area of both the tibial and femoral footprints were measured on MRI. The footprint dimensions were correlated with the recorded anthropometric data.

Results

The ACL tibial footprint length and area, and femoral footprint length and area were found to be 13.3 ± 2.23 mm, 142.6 ± 26.16 mm2, 11.2 ± 1.97 mm, 125.8 ± 28.75 mm2 respectively. Footprint in males was significantly larger than females. A weak (ρ- 0.21 to 0.4) correlation with weight and moderate (ρ- 0.41 to 0.6) correlation with height was observed. Multivariate linear regression analysis yielded height to be the only significant predictor of footprint dimension from which predictive equations were drawn.

Conclusions

Height was found to be the most significant predictor of footprint dimensions in our patients. The predictive equations and graphs can aid in preoperative surgical decision making resulting in a more anatomical ACL reconstruction and improve the post-operative results.

ACL reconstruction provides superior stability than ACL repair in patients with Schenck III and IV knee joint dislocations: first results of a 12 month follow-up study

PURPOSE

Acute knee dislocation is a rare but devastating multi-ligamentous knee injury with only limited evidence-based surgical technique recommendations. The aim of this study was a comparison of two different anterior cruciate ligament (ACL) restoration techniques as part of an early total surgical care concept: (1) repair of ACL with additional internal bracing (ACLIB) compared to; (2) ACL reconstruction with autograft (ACLR).

METHODS

Retrospective, clinical-study of patients with an acute type III or IV knee dislocation (according to Schenck classification), in which the ACL was treated with ACLIB or ACLR within 12 days. The PCL was sutured and internally braced in all cases. Medial and lateral complex injuries were repaired and additionally laterally augmented by an Arciero reconstruction. After a minimum 12 months follow-up different patient-reported outcome measurements (IKDC, Lysholm, VAS, Tegner Score) and instrumental stability assessment by Rolimeter -test and stress radiographs (Telos™) were analyzed. Groups were compared by t test with p < 0.05 considered significant.

RESULTS

In total, 20 patients (5 IIIM, 5 IIIL and 10 IV) were included in this study with an average follow-up of 13.7 ± 2.6 months. There were significant differences in instrumental stability testing (side-to-side difference (SSD) of anterior tibial translation: ACLIB 2.7 ± 1.5 mm vs. ACLR 1.3 ± 1.3; p = 0.0339) and stress radiography (SSD ACL: ACLIB 3.4 ± 2.2 mm vs. ACLR 0.4 ± 2.7; p = 0.0249) between groups. ACLIB group showed greater ROM in terms of flexion (SSD Flexion: ACLIB 7.8 ± 9.9° vs. ACLR 16 ± 7.0°; p = 0.0466; Total Flexion overall 125.5 ± 11.8°). No clinically relevant differences in patient-reported outcome scores (Lysholm Score: ACLIB 82 ± 16.4 vs. ACLR 85 ± 10.4; IKDC subjective score: ACLIB 70.4 ± 17 vs. ACLR 76.6 ± 8.3) were determined.

CONCLUSION

ACLR provides superior translational stability than ACLIB in terms of instrumental testing and stress radiography. Both techniques were equivalent with respect to PROMS and led to good and excellent clinical results.

LEVEL OF EVIDENCE

Retrospective cohort study, III.

More anterior placement of femoral tunnel position in ACL-R is associated with postoperative meniscus tears

PURPOSE

The purpose of this study was to investigate the relationship between tunnel position in ACL reconstruction (ACL-R) and postoperative meniscus tears.

METHODS

This was a single institution, case-control study of 170 patients status-post ACL-R (2010-2019) separated into two matched groups (sex, age, BMI, graft type). Group 1-symptomatic, operative meniscus tears (both de novo and recurrent) after ACL-R. Group 2-no postoperative meniscus tears. Femoral and tibial tunnel positions were measured by 2 authors via lateral knee radiographs that were used to measure two ratios (a/t and b/h). Ratio a/t was defined as distance from the tunnel center to dorsal most subchondral contour of the lateral femoral condyle (a) divided by total sagittal diameter of the lateral condyle along Blumensaat's line (t). The ratio b/h was defined as distance between the tunnel and Blumensaat's line (b) divided by maximum intercondylar notch height (h). Wilcoxon sign-ranks paired test was used to compare measurements between groups (alpha set at p < 0.05).

RESULTS

Group 1 had average follow up of 45 months and Group 2 had average follow up of 22 months. There were no significant demographic differences between Groups 1 and 2. Group 1-a/t was 32.0% (± 10.2), which was significantly more anterior than group 2, 29.3% (± 7.3; p < 0.05). There was no difference in average femoral tunnel ratio b/h or tibial tunnel placement between groups.

CONCLUSIONS

A relationship exists between more anterior/less anatomic femoral tunnel position and the presence of recurrent or de novo, operative meniscus tears after ACL-R. Surgeons performing ACL-R should strive for recreation of native anatomy via proper tunnel placement to maximize postoperative outcomes.

LEVEL OF EVIDENCE

Level III.

Comparison of Onlay Anchor Fixation Versus Transosseous Fixation for Lateral Extra-articular Tenodesis During Revision ACL Reconstruction

Background

There is evidence on the clinical effectiveness of the Lemaire technique for lateral extra-articular tenodesis (LET) in patients undergoing revision anterior cruciate ligament reconstruction (ACLR), but the best fixation technique is unknown.

Purpose

To compare the clinical outcomes of 2 fixation techniques after revision ACLR: (1) onlay anchor fixation, which would avoid tunnel conflict and physis injury, and (2) transosseous tightening and interference screw fixation. Pain at the area of LET fixation was also assessed.

Study Design

Cohort study; Level of evidence, 3.

Methods

This was a retrospective 2-center study of patients with first-time revision ACLR and either LET with anchor fixation (aLET) with a 2.4-mm suture anchor or LET with transosseous fixation (tLET). Outcomes at minimum 12-month follow-up were assessed with the International Knee Documentation Committee score, Knee injury and Osteoarthritis Outcome Score, visual analog scale for pain at the LET fixation area, Tegner score, and anterior tibial translation (ATT). A subgroup analysis within the aLET group investigated passing the graft over or under the lateral collateral ligament (LCL).

Results

In total, 52 patients were included (26 patients in each group); the mean ± SD follow-up was 13.7 ± 3.4 months. No statistically significant differences were detected between the groups with respect to patient-reported outcome scores, clinical examination, or instrumented testing (side-to-side difference in ATT at 30° of flexion; aLET, 1.5 ± 2.5 mm; tLET, 1.6 ± 1.7 mm). Clinical failure was detected in 1 patient with aLET and none with tLET. Subgroup analysis revealed a small, nonsignificant flexion deficit in knees in which the iliotibial band strand was passed under (n = 42) or over (n = 10) the LCL. No clinically relevant tenderness was detected at the area of LET fixation in any group (aLET, 0.6 ± 1.3; tLET, 0.9 ± 1.7; over the LCL, 0.2 ± 0.6; under the LCL, 0.9 ± 1.6).

Conclusion

Onlay anchor fixation and transosseous fixation of the LET were equivalent with respect to outcome scores and instrumented ATT testing. Clinically, there were minor differences in passage of the LET graft over or under the LCL.

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.

Robot-assisted all-epiphyseal anterior cruciate ligament reconstruction in skeletally immature patients: a retrospective study

PURPOSE

To review a series of adolescent patients with anterior cruciate ligament (ACL) injuries surgically treated with robot-assisted all-epiphyseal ACL reconstruction (ACLR), and to compare with the traditional freehand group.

METHODS

This retrospective clinical study included 16 patients with ACL injuries who underwent ACLR by robot-assisted technique or traditional freehand method from June 2018 to March 2020. All patients were divided into the robot-assisted group (6 patients) or the traditional surgery group (10 patients). The number of intra-operative fluoroscopies, operation time, accuracy of bone tunnel insertions, International Knee Documentation Committee (IKDC) subjective score and ligament laxity testing were recorded in the two groups.

RESULTS

All patients returned for follow-up, at a mean of 31.6 ± 4.5 months after surgery. The average age of the robot-assisted group was 12.2 ± 1.3 years. The number of intra-operative fluoroscopies was 10.9 ± 2.8 in the traditional freehand group, whereas it was only 3.0 ± 0.6 in the robot-assisted group, which was significantly lower (P < 0.05). The operative time in the robot-assisted group was shorter than that in the traditional freehand group (87 ± 10.7 min vs. 126 ± 12.1 min, P < 0.05). The distance between the center of actual insertion and the center of the idea insertion on both femoral and tibial intra-articular bone tunnel were 1.5 ± 0.3 mm and 1.6 ± 0.3 mm for the robot-assisted group and 2.7 mm ± 0.4 mm and 2.4 ± 0.4 mm for the traditional freehand group (P < 0.05). There were no significant differences between the two groups in function recovery at the last follow-up.

CONCLUSIONS

All-epiphyseal ACLR is a technically demanding procedure with a small margin of error. Robot-assisted treatment of ACL injuries in skeletally immature patients is more accurate than traditional freehand method, with shorter operation time and fewer intra-operative fluoroscopies.

Anatomic anterior cruciate ligament reconstruction: Freddie Fu's paradigm

Anterior cruciate ligament (ACL) reconstruction techniques have evolved over the past four decades. There is evidence that non-anatomic reconstruction techniques, such as traditional transtibial drilling, fail to recreate the native anatomy of the ACL, which can lead to increased rotatory knee instability, revision risk, and post-traumatic osteoarthritis. Anatomic ACL reconstruction has emerged as the gold standard, with the goal of restoring the patient's native anatomy and knee kinematics. This review will summarise the relevant anatomy, modern anatomic ACL reconstruction techniques, and literature supporting anatomic ACL reconstruction as the new paradigm. LEVEL OF EVIDENCE: Level V, review article.

Computer-assisted navigation in ACL reconstruction improves anatomic tunnel placement with similar clinical outcomes

BACKGROUND

While the use of navigation systems in anterior cruciate ligament (ACL) reconstruction theoretically improves tunnel placement accuracy and clinical outcomes, the existing literature remains inconclusive. We aimed to evaluate the potential benefits of navigated ACL reconstruction on tunnel placement and clinical outcomes.

METHODS

In this retrospective study, we evaluated a cohort of patients who underwent conventional or navigated (OrthoPilot system) primary ACL reconstruction at our institution from June 2004 to October 2009. Anteroposterior and lateral radiographic knee assessments were evaluated to assess postoperative tunnel positioning. Clinical outcomes, including the International Knee Documentation Committee classification, Lysholm score, and Tegner score, were evaluated preoperatively and 1-year postoperatively. Radiographic and clinical outcomes were compared and analysed using independent 2-sample t-tests and Chi-square tests.

RESULTS

Sixty patients met the inclusion criteria and were included for analysis, comprising of 26 navigated and 34 conventional reconstructions. Postoperative radiographs showed no differences in tibial tunnel position between both groups, but a significantly smaller deviation from the recommended position in the navigated group (navigated: 5.96 %; conventional: 7.92 %; p = 0.008). Femoral tunnel placements in the navigated group were significantly more perpendicularly away from the Blumensaat line (navigated: 38.90 %; conventional: 31.94 %; p = 0.001), with a greater deviation from recommended position (navigated: 11.00 %; conventional: 6.94 %; p = 0.009). There were no differences in 1-year postoperative clinical outcomes (p > 0.05).

CONCLUSION

Navigated ACL reconstruction resulted in a more anatomic femoral tunnel placement and similar clinical outcomes as conventional reconstruction. Further research should be conducted to clarify the potential biomechanical and clinical impacts of navigated ACL reconstruction.

Preoperative excessive lateral anterior tibial subluxation is related to posterior tibial tunnel insertion with worse sagittal alignment after anterior cruciate ligament reconstructions

Objective

To investigate whether preoperative lateral anterior tibial subluxation (LATS) measured from magnetic resonance imaging (MRI) can influence tibial insertion and postoperative sagittal alignment after anterior cruciate ligament reconstructions (ACLRs).

Methods

84 patients who underwent single-bundle ACLRs were retrospectively investigated. Among them, 39 patients (LATS of <6 mm) 23 patients (LATS of ≥6 mm and <10 mm) and 22 patients (excessive LATS of ≥10 mm) were defined as group 1, 2 and 3, respectively. LATS, the position of graft insertion into tibia as ratio of anterior-posterior width (AP ratio) and the sagittal graft angle (SGA) were postoperatively assessed from MRI at 2-year follow-up. Following linear regression analyses were employed.

Results

The group 3 exhibited the largest preoperative LATS and remained the most postoperative LATS. Moreover, the group 3 possessed the most posteriorly located tunnel insertion with the largest AP ratio and the most vertical graft orientation. Of all included patients, a moderate correlation was demonstrated between pre- and postoperative LATS (r = 0.635). A low correlation was observed between preoperative LATS and AP ratio (r = 0.300) and a moderate correlation was displayed between AP ratio and SGA (r = 0.656).

Conclusion

For ACL injuries with excessive LATS (≥10 mm), most posteriorly located tibial insertion was found out, and worse sagittal alignment containing high residual LATS was associated with more vertical graft orientation following ACLRs.

Failure of primary ACL repair with dynamic intraligamentary stabilization may result in a high risk of two-stage ACL reconstruction: a case series of ten patients

PURPOSE

Dynamic Intraligamentary Stabilization (DIS) is a technique for the repair of acute anterior cruciate ligament (ACL) injuries. The purpose of this study was to investigate the potential challenges of ACL reconstruction (ACLR) following failure of DIS.

METHODS

A retrospective analysis of patients with failure of primary ACL repair performed with DIS was undertaken. Failure was defined as abnormal knee laxity (positive Lachman and/or pivot shift) and/or severely restricted range of motion. Medical and surgical records were reviewed and preoperative standard anteroposterior and lateral X-rays were assessed.

RESULTS

Between July 2015 and May 2022, 10 patients (3 males, 7 females, median age 28 years, range 18-52 years) with failure of DIS were referred to and surgically treated at a single centre. In four patients, single-stage ACLR was performed following the removal of the tibial monoblock. In six patients, arthrofibrosis and excessive tibial tunnel enlargement following the removal of the monoblock prevented single-stage ACLR. These patients underwent arthroscopic arthrolysis and tibial tunnel bone grafting as a first-stage revision procedure.

CONCLUSION

In the present case series, single-stage ACLR was performed in only four (40%) of ten patients following failure of ACL repair with DIS. Arthrofibrosis and excessive tibial tunnel enlargement following the removal of the monoblock prevented single-stage ACLR in six (60%) patients. It is important for clinicians to inform patients that, in the event of failure of ACL repair with DIS, they may run a high risk of undergoing two-stage ACLR.

LEVEL OF EVIDENCE

Level IV, Case Series.

Systematic Review of Cadaveric Studies on Anterior Cruciate Ligament Anatomy Focusing on the Mid-substance Insertion and Fan-like Extension Fibers

PURPOSE

The purpose of this systematic review was to review the anatomical reports concerning the anterior cruciate ligament (ACL) focusing on the mid-substance insertion and fan-like extension fibers, or direct and indirect insertions.

METHODS

Following the PRISMA, data collection was performed. PubMed, Web of Science, and the Cochran library were searched with the terms "anterior cruciate ligament reconstruction", "anatomy", and "cadaver". Studies were included when anatomical dissection of the ACL with cadavers was performed. Biomechanical studies without a detailed description of the anatomical dissection, reviews, and studies not including pictures of the anatomical specimens were excluded from this study. In the full article review, documentation of the mid-substance insertion and fan-like extension fibers, or direct and indirect insertions in the ACL morphology was evaluated in detail.

RESULTS

Fifty-seven studies were included for detailed evaluation. In 2006, Mochizuki et al. reported a macroscopic differentiation between the mid-substance insertion and fan-like extension fibers in the ACL footprint. In 2010, Iwahashi et al. detected the existence of direct and indirect insertions within the femoral ACL footprint, microscopically. Following Mochizuki's report, anatomical evaluation of the mid-substance insertion and fan-like extension fibers, or direct and indirect insertions was reported in 16 of 51 ACL anatomical studies. In studies focusing on the morphology of the ACL, 16 of 28 studies addressed this subject. In these studies, the mid-substance insertion and fan-like extension fibers were differentiated macroscopically, and the direct and indirect insertions were differentiated microscopically within the ACL footprint. Fan-like extension fibers or indirect insertion was reported to surround the mid-substance insertion or direct insertion within the femoral ACL footprint.

CONCLUSIONS

The results of this systematic review showed that, the existence of the mid-substance insertion and fan-like extension fibers, or direct and indirect insertions in ACL morphology is being recognized more widely. These structures should be taken into consideration when surgeons perform ACL surgery.

LEVEL OF EVIDENCE

III. Systematic review of Level-III studies.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s43465-022-00695-4.

Anterior cruciate ligament foot plate anatomy: 3-dimensional and 2-dimensional MRI evaluation with arthroscopy assessment in a subset of patients

OBJECTIVES

ACL reconstruction tunnel location is an important predictor for outcomes after surgery. The aim was to establish 3D and 2D MRI radiological measurements for native ACL tibial footprint that can provide information to facilitate pre-operative planning for anatomical graft placement. The measurements were also correlated in a subset of patients on arthroscopy.

METHODS

Retrospective evaluation of a consecutive series of knee MRIs with both 2D and 3D MR imaging was performed in 101 patients with 43 men and 66 women and ages 39.5 ± 11.9 years. Two measurements were obtained, tibial to ACL and intermeniscal ligament to ACL (T-ACL) and (IM-ACL), respectively. In a cohort of 18 patients who underwent knee arthroscopy, the T-ACL and IML-ACL distances were also determined by an orthopedic surgeon using a standard scale. ICC, Pearson correlation, and Bland-Altman plot were generated.

RESULTS

For readers 1 and 2, the mean differences between 2D and 3D measurements of T-ACL and IM-ACL were 1.17 and 1.03 mm and 0.65 and 0.65 mm, respectively. The 2D measurements of T-ACL and IM-ACL were larger than the 3D measurements for both readers. The inter-reader reliability was excellent on 2D (0.81-0.96) and fair to excellent on 3D MRI (0.59-0.90). The mean arthroscopic IML-ACL was closer to that of 3D MRI compared to 2D MRI. The mean arthroscopic T-ACL was closer to 2D MRI than 3D MRI.

CONCLUSIONS

Both 2D and 3D MRI show inter-reader reliability with small inter-modality mean differences in the measurements from the tibial or inter-meniscal ligament margins.

KEY POINTS

• The mean differences between 2D and 3D measurements of tibia-ACL and intermeniscal ligament-ACL are small (< 1.2 mm). • As compared to arthroscopy, the mean T-ACL and IML-ACL were closer to measurements from 2D and 3D MRI, respectively. • Both 2D and 3D MRI can be reliably used to delineate ACL foot plate anatomy.

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.

Multi-Stage Platform for (Semi-)Automatic Planning in Reconstructive Orthopedic Surgery

Intricate lesions of the musculoskeletal system require reconstructive orthopedic surgery to restore the correct biomechanics. Careful pre-operative planning of the surgical steps on 2D image data is an essential tool to increase the precision and safety of these operations. However, the plan’s effectiveness in the intra-operative workflow is challenged by unpredictable patient and device positioning and complex registration protocols. Here, we develop and analyze a multi-stage algorithm that combines deep learning-based anatomical feature detection and geometric post-processing to enable accurate pre- and intra-operative surgery planning on 2D X-ray images. The algorithm allows granular control over each element of the planning geometry, enabling real-time adjustments directly in the operating room (OR). In the method evaluation of three ligament reconstruction tasks effect on the knee joint, we found high spatial precision in drilling point localization (ε<2.9mm) and low angulation errors for k-wire instrumentation (ε<0.75∘) on 38 diagnostic radiographs. Comparable precision was demonstrated in 15 complex intra-operative trauma cases suffering from strong implant overlap and multi-anatomy exposure. Furthermore, we found that the diverse feature detection tasks can be efficiently solved with a multi-task network topology, improving precision over the single-task case. Our platform will help overcome the limitations of current clinical practice and foster surgical plan generation and adjustment directly in the OR, ultimately motivating the development of novel 2D planning guidelines.

Tibial internal rotation in combined anterior cruciate ligament and high-grade anterolateral ligament injury and its influence on ACL length

Background

Assessment of combined anterolateral ligament (ALL) and anterior cruciate ligament (ACL) injury remains challenging but of high importance as the ALL is a contributing stabilizer of tibial internal rotation. The effect of preoperative static tibial internal rotation on ACL -length remains unknown. The aim of the study was analyze the effect of tibial internal rotation on ACL length in single-bundle ACL reconstructions and to quantify tibial internal rotation in combined ACL and ALL injuries.

Methods

The effect of tibial internal rotation on ACL length was computed in a three-dimensional (3D) model of 10 healthy knees with 5° increments of tibial internal rotation from 0 to 30° resulting in 70 simulations. For each step ACL length was measured. ALL injury severity was graded by a blinded musculoskeletal radiologist in a retrospective analysis of 61 patients who underwent single-bundle ACL reconstruction. Preoperative tibial internal rotation was measured in magnetic resonance imaging (MRI) and its diagnostic performance was analyzed.

Results

ACL length linearly increased 0.7 ± 0.1 mm (2.1 ± 0.5% of initial length) per 5° of tibial internal rotation from 0 to 30° in each patient.

Seventeen patients (27.9%) had an intact ALL (grade 0), 10 (16.4%) a grade 1, 21 (34.4%) a grade 2 and 13 (21.3%) a grade 3 injury of the ALL. Patients with a combined ACL and ALL injury grade 3 had a median static tibial internal rotation of 8.8° (interquartile range (IQR): 8.3) compared to 5.6° (IQR: 6.6) in patients with an ALL injury (grade 0–2) (p = 0.03). A cut-off > 13.3° of tibial internal rotation predicted a high-grade ALL injury with a specificity of 92%, a sensitivity of 30%; area under the curve (AUC) 0.70 (95% CI: 0.54–0.85) (p = 0.03) and an accuracy of 79%.

Conclusion

ACL length linearly increases with tibial internal rotation from 0 to 30°. A combined ACL and high-grade ALL injury was associated with greater preoperative tibial internal rotation. This potentially contributes to unintentional graft laxity in ACL reconstructed patients, in particular with concomitant high-grade ALL tears.

Study design

Cohort study; Level of evidence, 3.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-022-05218-8.

Posteriorly positioned femoral grafts decrease long-term failure in anterior cruciate ligament reconstruction, femoral and tibial graft positions did not affect long-term reported outcome

PURPOSE

To investigate the effect that femoral and tibial tunnel positions have on long-term reported and clinical outcome and to identify a safe zone based on favourable outcome.

METHODS

Seventy-eight patients from a previous randomised controlled trial were included and were followed with a mean follow-up of 11.4 years. All patients had primary trans-tibial anterior cruciate ligament reconstruction performed. The femoral and tibial tunnel positions were visualised and translated in percentages with three-dimensional computed tomography post-operatively. There were 3 separate outcome variables: patient-reported outcome measured with the IKDC Subjective Knee Form, overall failure, and radiographic osteoarthritis. The correlation between tunnel aperture positions and outcome was determined with multivariate regression. The area with best outcome was defined as the safe zone and was determined with Youden's index in conjunction with receiver operating characteristics.

RESULTS

No significant relationship was found between tunnel aperture positions and IKDC Subjective Knee Form at 10-year follow-up. The posterior-to-anterior femoral tunnel aperture position parallel to Blumensaat line showed a significant relationship (p = 0.03) to overall failure at 10-year follow-up. The mean posterior-to-anterior tunnel position of the group that did not fail was 37.7% compared to 44.1% in the overall failure group. Femoral tunnel apertures placed further anteriorly had more overall failures at long-term. The cut-off point lies at 35.0% from posterior-to-anterior parallel to Blumensaat. Of the 16 overall failures, 15 (93.8%) were placed further anteriorly than the cut-off point. No significant relationship was found between tunnel aperture positions and radiographic osteoarthritis.

CONCLUSION

Femoral and tibial tunnel positions were not associated with long-term patient-reported outcome and radiographic osteoarthritis. Long-term overall failure was more frequently seen in patients with a more anteriorly placed femoral tunnel. This study identified a safe zone located at the most posterior 35% of the femoral condyle parallel to Blumensaat. This knowledge offers guidance to surgeons to operate more precisely and accurately and reconstruct a long-lasting graft.

LEVEL OF EVIDENCE

Level III.

Rate of Tibial Tunnel Malposition Is Not Changed by Drilling Entirely Within the Stump of Preserved Remnants During ACL Reconstruction: A Prospective Comparative 3D-CT Study

Background:

Remnant preservation during anterior cruciate ligament (ACL) reconstruction (ACLR) is controversial, and it is unclear whether the stump aids or obscures tibial tunnel positioning.

Purpose/Hypothesis:

The aim of this study was to determine whether the rate of tibial tunnel malposition is influenced by remnant preservation. The hypothesis was that using a remnant-preserving technique to drill entirely within the tibial stump would result in a significant reduction in tibial tunnel malposition as determined by postoperative 3-dimensional computed tomography (3D-CT).

Study Design:

Cohort study; Level of evidence, 2.

Methods:

Patients undergoing ACLR between October 2018 and December 2019 underwent surgery with a remnant-preserving technique (RP group) if they had a large stump present (>50% of the native ACL length) or if there was no remnant or if it was <50% of the native length of the ACL, they underwent remnant ablation (RA group) and use of standard landmarks for tunnel positioning. The postoperative tunnel location was reported as a percentage of the overall anteroposterior (AP) and mediolateral (ML) dimensions of the tibia on axial 3D-CT. The tunnel was classified as anatomically placed if the center lay between 30% and 55% of the AP length and between 40% and 51% of the ML length.

Results:

Overall, 52 patients were included in the study (26 in each group). The mean tunnel positions were 36.8% ± 5.5% AP and 46.7% ± 2.9% ML in the RP group and 35.6% ± 4.8% AP and 47.3% ± 2.3% ML in the RA group. There were no significant differences in the mean AP (P = .134) and ML (P = .098) tunnel positions between the groups. Inter- and intraobserver reliability varied between fair to excellent and good to excellent, respectively. There was no significant difference in the rate of malposition between groups (RP group, 7.7%; RA group, 11.5%; P ≥ .999).

Conclusion:

Drilling entirely within the ACL tibial stump using a remnant-preserving reconstruction technique did not significantly change the rate of tunnel malposition when compared with stump ablation and utilization of standard landmarks.

[Combined PCL ligament bracing and ACL reconstruction in acute knee dislocation (Schenck IV) - The Hamburg Approach : Video article]

OBJECTIVE

Stepwise reconstruction of knee stability and physiological kinematics in acute knee dislocation.

INDICATIONS

The operative technique is demonstrated in a case of multiligamentous injury of the knee with involvement of both cruciate ligaments and additional medial and lateral peripheral injuries (type IV according to Schenck classification).

CONTRAINDICATIONS

Critical soft tissue conditions, infections, old age, obesity, lack of compliance.

SURGICAL TECHNIQUE

Time-limited arthroscopy in order to primarily identify and treat posterior horn/root injuries of the meniscus and concomitant intra-articular injuries. Anatomical placement of anterior cruciate ligament (ACL) drill wires for later ACL tunnel drilling is arthroscopically guided. Subsequent conversion to an anteromedial arthrotomy and ligament bracing of the posterior cruciate ligament. The ACL is reconstructed using the ipsilateral semitendinosus tendon. Medial and lateral peripheral injures are anatomically reconstructed followed by a posterolateral augmentation in a technique described by Arciero.

FOLLOW-UP

Limited weight bearing for 6 weeks and stepwise increase of flexion using a standard knee brace and close clinical monitoring.

EVIDENCE

Ligament bracing of both cruciate ligaments is an established treatment technique in acute knee dislocations and has been proven to achieve good to excellent clinical results. In an ongoing clinical study primary ACL reconstruction as a modified treatment approach indicated superior stability in a 12-month follow-up in patients with acute knee dislocations.

Influence of femoral tunnel exit on the 3D graft bending angle in anterior cruciate ligament reconstruction

Purpose

To quantify the influence of the femoral tunnel exit (FTE) on the graft bending angle (GBA) and GBA-excursion throughout a full range of motion (ROM) in single-bundle anterior cruciate ligament (ACL) reconstruction.

Methods

Three-dimensional (3D) surface models of five healthy knees were generated from a weight-bearing CT obtained throughout a full ROM (0, 30, 60, 90, 120°) and femoral and tibial ACL insertions were computed. The FTE was simulated for 16 predefined positions, referenced to the Blumensaat's line, for each patient throughout a full ROM (0, 30, 60, 90, 120°) resulting in a total of 400 simulations. 3D GBA was calculated between the 3D directional vector of the ACL and the femoral tunnel, while the intra-articular ACL insertions remained unchanged. For each simulation the 3D GBA, GBA-excursion, tunnel length and posterior tunnel blow-out were analysed.

Results

Overall, mean GBA decreased with increasing knee flexion for each FTE (p < 0.001). A more distal location of the FTE along the Blumensaat's line resulted in an increase of GBA and GBA-excursion of 8.5 ± 0.6° and 17.6 ± 1.1° /cm respectively (p < 0.001), while a more anterior location resulted in a change of GBA and GBA-excursion of -2.3 ± 0.6° /cm (+ 0.6 ± 0.4°/ cm from 0–60° flexion) and 9.8 ± 1.1 /cm respectively (p < 0.001).

Mean tunnel length was 38.5 ± 5.2 mm (range 29.6–50.5). Posterior tunnel blow-out did not occur for any FTE.

Conclusion

Aiming for a more proximal and posterior FTE, with respect to Blumensaat’s line, reliably reduces GBA and GBA-excursion, while preserving adequate tunnel length. This might aid to reduce excessive graft stress at the femoral tunnel aperture, decrease femoral tunnel widening and promote graft-healing.

Level of Evidence

IV

Patients with a quadriceps tendon shorter than 60 mm require a patellar bone plug autograft in anterior cruciate ligament reconstruction

PURPOSE

To assess the length and thickness of the quadriceps tendon (QT) and anterior cruciate ligament (ACL) to predict the required QT length for individual ACL reconstruction.

METHODS

Thirty patients (9 females, 21 males; mean age 24.5 years; mean height 169.3 cm) who underwent ACL reconstruction using the QT with a bone plug autograft were enrolled. The length and thickness of the QT on preoperative magnetic resonance imaging (MRI) were compared with those measured under direct visualization. The ACL length was measured on preoperative MRI and three-dimensional computed tomography after ACL reconstruction. The QT length on MRI was compared with the required graft length, and the factors related to an adequate QT length were assessed.

RESULTS

The mean QT length on MRI was 60.8 ± 1.3 mm and was significantly positively correlated with the QT length under direct visualization (P < 0.01). On MRI, the mean ACL length was 30.8 ± 1.2 mm and the mean QT thickness was 6.3 ± 0.2 mm. Although the mean QT was 0.1 mm longer than the mean required graft length, the QT on MRI was shorter than the required graft length in 37% of patients (11/30). Adequate QT length was related to a QT length of more than 60 mm, but not to age, sex, height, or ACL length.

CONCLUSION

Although preoperative MRI predicted the required QT length for ACL reconstruction, 37% of patients lacked an adequate QT length, and a QT shorter than 60 mm required the addition of patellar bone.

LEVEL OF EVIDENCE

III.

Effect of Tibial Tunnel Placement Using the Lateral Meniscus as a Landmark on Clinical Outcomes of Anatomic Single-Bundle Anterior Cruciate Ligament Reconstruction

BACKGROUND

It remains unclear if use of the lateral meniscus anterior horn (LMAH) as a landmark will produce consistent tunnel positions in the anteroposterior (AP) distance across the tibial plateau.

PURPOSE

To evaluate the AP location of anterior cruciate ligament (ACL) reconstruction tibial tunnels utilizing the LMAH as an intra-articular landmark and to examine how tunnel placement affects knee stability and clinical outcomes.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

A retrospective review was conducted of 98 patients who underwent primary ACL reconstruction with quadrupled hamstring tendon autografts between March 2013 and June 2017. Patients with unilateral ACL injuries and a minimum follow-up of 2 years were included in the study. All guide pins for the tibial tunnel were placed using the posterior border of the LMAH as an intra-articular landmark. Guide pins were evaluated with the Bernard-Hertel grid in the femur and the Stäubli-Rauschning method in the tibia. Patients were divided by the radiographic location of the articular entry point of the guide pin with relation to the anterior 40% of the tibial plateau. Outcomes were evaluated by the Marx Activity Scale and International Knee Documentation Committee (IKDC) form. Anterior knee laxity was evaluated using a KT-1000 arthrometer and graded with the objective portion of the IKDC form. Rotational stability was evaluated using the pivot-shift test.

RESULTS

A total of 60 patients were available for follow-up at a mean 28.6 months. The overall percentage of AP placement of the tibial tunnel was 39.3% ± 3.8% (mean ± SD; range, 31%-47%). Side-to-side difference of anterior knee laxity was significantly lower in the anterior group than the posterior group (1.2 ± 1.1 mm vs 2.5 ± 1.3 mm; P < .001; r = 0.51). The percentage of AP placement of the tibial tunnel demonstrated a positive medium correlation with side-to-side difference of anterior knee laxity as measured by a KT-1000 arthrometer (r = 0.430; P < .001). The anterior group reported significantly better distribution of IKDC grading as compared with the posterior group (26 grade A and 6 grade B vs 15 grade A and 13 grade B; P = .043; V = 0.297). The pivot-shift test results and outcome scores showed no significant differences between the groups.

CONCLUSION

Using the posterior border of the LMAH as an intraoperative landmark yields a wide range of tibial tunnel locations along the tibial plateau, with anterior placement of the tibial tunnel leading toward improved anterior knee stability.

Femoral Intercondylar Notch: Gross Anatomy and Histology of the Connective Tissue Lining of its Roof: A Pilot Study

PURPOSE

We have consistently observed a connective tissue lining over the intercondylar notch's roof (CTLINR) during arthroscopic surgeries of the knee joint. As there is a strong association of the intercondylar fossa with the anterior cruciate ligament (ACL), we believe that this tissue must be having some role in the functioning of the ACL. The purpose of this pilot study was to investigate the anatomic characteristics of the CTLINR.

METHODS

In this observational anatomical study, we have investigated the gross anatomical and histological features of the CTLINR in four knees of two fresh frozen non-embalmed cadavers. We have also studied its ultrastructural characteristics by obtaining an arthroscopic biopsy of the tissue from a patient undergoing ACL reconstruction.

RESULTS

At gross examination, the CTLINR had a typical glistening white surface with transversely oriented fibres. It entirely covered the roof of the intercondylar notch and was soft to touch. Histological examination with haematoxylin-eosin stain revealed fibro-collagenous tissue with intervening blood vessels. Transmission electron microscopy manifested loosely arranged collagen fibres of variable diameter.

CONCLUSION

The histological and electron microscopic characteristics of the tissue differentiate it from the ACL and its femoral enthesis, suggesting that it was a distinct anatomical structure. As it entirely covered the roof of the intercondylar fossa and had a smooth surface and soft consistency, it may protect the reconstructed ACL from graft abrasion. Furthermore, as it had a characteristic arthroscopic appearance, future research can investigate its role in femoral tunnel positioning.

Assessment of thickness of in vivo autograft tendons around the knee and its correlation with anthropometric data, thickness of patella and anterior cruciate ligament tibial foot print diameter

Inadequate diameters of the autograft tendons are known to be a major cause of graft failure in ligament reconstruction. The purpose of the study was to measure the in-vivo thickness of the available autograft options around the knee and to seek a correlation between the thickness of the tendons and the anthropometric data, patellar thickness and anterior cruciate ligament (ACL) footprint sagittal diameter. Magnetic resonance imaging of 104 consecutive patients with suspected knee injuries were utilized for measurement of the in vivo thickness of pes anserinus tendon (diameter and cross-sectional area [CSA]), patellar tendon (PT) and quadriceps tendon (QT). Pearson’s coefficient was used to find out the relationship between the tendon thickness and anthropometric data, thickness of patella and ACL tibial foot print sagittal diameter. The mean diameters and CSA of the semitendinosus tendon (ST) and gracilis tendon (GT) were 3.77±0.49 mm, 11.62±1.62 mm² and 2.87±0.27 mm, 6.64±1.18 mm² respectively. QT and PT thicknesses were 7.36±0.87 mm and 4.50±0.62 mm respectively. Height and the patellar thickness were seen to have moderate correlation with ST and PT thickness. Weak correlation was seen between the other anthropometric variables and tendon thickness. Magnetic resonance imaging (MRI) assessment of tendon sizes is a reliable method with good inter and intra-rater agreement. Assessment of these anatomical structures with help of MRI would be helpful in preoperative planning and can help in identifying those patients at risk of having smaller tendons.

Anterior root of lateral meniscus and medial tibial spine are reliable intraoperative landmarks for the tibial footprint of anterior cruciate ligament

PURPOSE

The aims of the present study were (1) to investigate the tibial footprint location of the anterior cruciate ligament (ACL) in both ACL-ruptured and ACL-intact patients, (2) to identify the relationship of the tibial footprint to the anterior root of the lateral meniscus (ARLM) and medial tibial spine (MTS), and (3) to evaluate the reliability of the ARLM and MTS for identifying the center of the tibial ACL footprint.

METHODS

Magnetic resonance images of 90 knees with ACL rupture and 90 matched-controlled knees were used to create three-dimensional models of the tibia. The tibial ACL footprint was outlined on each model, and its location was measured using an anatomical coordinate system.

RESULTS

No significant difference in the location of the tibial footprint was found between ACL-ruptured and ACL-intact knees. The tibial ACL footprint was located in very close proximity to the ARLM, especially in the M/L direction. The safe zone of tibial tunnel reaming for avoiding damage to the ARLM was 2.6 mm lateral to the center of the native tibial footprint. Both the ARLM and MTS were reliable intraoperative landmarks for identifying the tibial footprint.

CONCLUSIONS

Orthopedic surgeons should be aware of the safe zone of tibial tunnel reaming for avoiding injury to the ARLM. Both the ARLM and MTS might be reliable landmarks for identifying the center of the tibial ACL footprint and may facilitate tibial tunnel placement during anatomical single-bundle ACL reconstruction, especially in cases of revision where the tibial ACL stump is not available.

LEVEL OF EVIDENCE

Level III.

Influence of selected plane on the evaluation of tibial tunnel locations using a three-dimensional bone model in double-bundle anterior cruciate ligament reconstruction

BACKGROUND

The purpose of this study was to investigate the influence of a selected plane on the evaluation of tibial tunnel locations following anterior cruciate ligament reconstruction (ACLR) between two planes: the plane parallel to the tibial plateau (Plane A) and the plane perpendicular to the proximal tibial shaft axis (Plane B).

METHODS

Thirty-four patients who underwent double-bundle ACLR were included. Three-dimensional model of tibia was created using computed tomography images 2 weeks postoperatively, and tibial tunnels of the anteromedial bundle (AMB) and posterolateral bundle (PLB) were extracted. To evaluate tibial tunnel locations, two planes (Planes A and B) were created. The locations of the tibial tunnel apertures of each bundle were evaluated using a grid method and compared between Planes A and B. The difference in coronal alignment between Planes A and B were also assessed.

RESULTS

The AMB and PLB tunnel apertures in Plane A were significantly more laterally located than in Plane B (mean difference; AMB, 1.5%; PLB, 1.7%, P < 0.01). There were no significant differences in the anteroposterior direction between the planes. Coronal alignment difference between the planes was 16.8 ± 2.2°; Plane B was more valgus than Plane A.

CONCLUSION

Although tibial tunnel locations were not significantly influenced by the selected planes in the AP direction, subtle but statistically significant differences were found in the ML direction between the Planes A and B in double-bundle anterior cruciate ligament reconstruction. The findings suggest that both Planes A and B can be used in the assessment of tibial tunnel locations after anterior cruciate ligament reconstruction.

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.

Does the position of interference screw in tibial tunnel effect anatomic orientation in single bundle anterior cruciate ligament reconstruction?

Background/objective

The purpose of the study was to evaluate the change in orientation of the reconstructed ACL with the change in position of the interference screw in the tibial tunnel.

Method

It was a retrospective review of Magnetic Resonance Imaging (MRI) in which 51 normal and 61 MRI of patients who had undergone ACL reconstruction at our institute were evaluated. Postoperative ACL reconstruction group MRI studies were obtained and evaluated by two sports medicine fellows independently to assess the position of interference screw, distance of the graft from the anterior cortex of tibia and inclination of the graft. The data was collected and compared with MRI data of normal ACL patients.

Results

There were total 61 patients with ACL reconstruction. 32 patients had anterior screw placement and 29 patients had posterior screw placement in the tibial tunnel. The distance of the graft from the anterior cortex was 39.18% in ACL intact group, 50.35% in anterior screw group and 41.64% in posterior screw group. The inclination angle was 44.49⁰ in intact group, 49.69° and 42.20° in anterior and posterior screw group respectively. The difference between intact group and anterior screw group was statistically significant.

Conclusion

Posterior position of interference screw in tibial tunnel increases graft obliquity than anterior position and decreases its distance from the anterior tibial cortex. This increased graft obliquity and distance from the anterior tibial cortex is similar to the native ACL.

Clinico-radiological outcomes following anatomical anterior cruciate ligament reconstruction using the TransLateral, all-inside technique

We present early clinical outcomes of patients following anatomical anterior cruciate ligament reconstruction using a TransLateral, single bundle, all-inside technique with a one-year follow-up and radiological evaluation of socket position. Eligible Patients who underwent a primary ACL reconstruction, using the TransLateral, all-inside technique alone, between Jan 2013 and Feb 2016 were included in this study. Of this group, all patients underwent isolated semitendinosus graft harvest. The Lysholm knee scores were measured preoperatively and at one-year follow-up in 40 patients who underwent ACL reconstruction. Postoperatively, antero-posterior and lateral radiographs were obtained to evaluate the position of the femoral socket (using the Bernard and Hertel Grid) and tibial socket (using the Amis-Jakob line). There were 36 males and 4 females with a mean age of 27.1 years (range 16-49). There was a single non-surgical related mortality prior to the one year follow up. We report no postoperative infections or graft failure at one year. The mean preoperative Lysholm score was 68.7 (Range: 29-95). The mean Lysholm score increased to 92.5% (Range: 59-100, p < 0.05). Evaluation of femoral sockets revealed accurate positioning on the Bernard and Hertel Grid with a mean ACL center of 27% along Blumensaat's line and 34% of the height of the intercondylar notch. The mean tibial socket position was 41.8% (Range: 32%-47%) along the Amis-Jakob Line. Our single surgeon case series utilizing the all-inside, TransLateral ACLR technique highlights good early outcomes with no postoperative complications or graft failure at one year.

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.

[Arthroscopic anterior cruciate ligament reconstruction via tibial tunnel made by three-portal technique]

Objective

To evaluate the effectiveness of arthroscopic anterior cruciate ligament (ACL) reconstruction via tibial tunnel made by three-portal technique.

Methods

Between July 2015 and December 2016, 45 patients with ACL ruptures were treated. There were 29 males and 16 females with an average age of 27.5 years (range, 18-42 years). There were 18 cases in the left side and 27 cases in the right side. There were 28 cases of sports injuries, 13 cases of traffic accidents, and 4 cases of other injuries. The average time from injury to operation was 21.6 days (range, 5-36 days). There were 25 cases of simple ACL injury and 20 cases of ACL complicated with medial collateral ligament, medial meniscus or lateral meniscus injuries. The Lachman tests of all patients were positive. The pivot shift tests of all patients were positive with grade Ⅰ in 27 cases, grade Ⅱ in 13 cases, and grade Ⅲ in 5 cases. The preoperative International Knee Documentation Committee (IKDC) score was 70.28±6.12, and the Lysholm score was 63.27±7.62. All patients underwent arthroscopic single-bundle ACL reconstruction, and the tibial tunnel was created through the anterolateral, high anteromedial, and additional low anteromedial approaches.

Results

All incisions healed by the first intention. All patients were followed up 18.7 months on average (range, 14-32 months). The three-dimensional CT at 3 days after operation showed that the tibial tunnel positions were accurate and the middle points were located in the 36.81%-43.35% of tibial plateau on sagittal plane. The medial borders of the tibial tunnel on coronal plane were located at the lateral to the medial eminence of the tibia. There were 3 cases of thrombosis of intermuscular vein of lower limbs, 2 cases of joint swelling and pain, and 3 cases of stiffness of knee joint. At last follow-up, the Lachman tests of all patients were negative and the pivot shift test were negative in 42 patients and positive in 3 patients (grade Ⅰ). The IKDC score (92.59±4.36) and Lysholm score (93.15±5.53) were significantly higher than preoperative scores ( t=11.35, P=0.00; t=12.27, P=0.00).

Conclusion

Arthroscopic ACL reconstruction via tibial tunnel made by three-portal technique, which was simple and accurate, can obtain the satisfactory function of the knee in the early stage after operation.

No added value using SPECT/CT to analyze persistent symptoms after anterior cruciate ligament reconstruction

PURPOSE

To evaluate the diagnostic and clinical value of SPECT/CT compared to the standard algorithm for patients with persistent symptoms after anterior cruciate ligament reconstructions. The standard algorithm uses clinical information, conventional radiographs, MRI and CT scan, while the trial algorithm uses the same information but SPECT/CT in addition.

METHODS

In a diagnostic comparative trial three experienced surgeons evaluated 23 consecutive patients with persistent symptoms after ACL reconstruction using first standard and second the trial algorithm with a time interval. Each rater had to establish a diagnosis and therapeutic decision with each algorithm. On MRI, graft continuity, bone marrow edema, chondral and meniscal lesions, femoral notch osteophytes were evaluated. Bone tracer uptake in SPECT/CT was anatomically analyzed and compared with MRI findings. MRI findings and SPECT/CT tracer uptake were correlated using Spearman's rho test.

RESULTS

Additional SPECT/CT analysis did not change diagnosis in any case and did not correlate with clinical graft integrity. Treatment decisions remained unchanged as well. Chondral lesions, arthritic changes, meniscal lesions, graft impingement are best visualized in MRI and showed correspondent tracer uptake in SPECT/CT. Tunnel position was well classified with standard CT scan and showed no correlation with SPECT/CT tracer uptake.

CONCLUSION

Information derived by SPECT/CT in addition to the standard algorithm using clinical information, X-rays, MRI, and CT scan did not change the diagnosis or treatment plan. There is currently no justification to implement SPECT/CT for patients with persistent symptoms after anterior cruciate ligament reconstructions.

LEVEL OF EVIDENCE

Level II: diagnostic comparative study.

Comparison of Tibial Tuberosity-Trochlear Groove (TT-TG) distances between different anterior cruciate ligament reconstructions: A retrospective clinical and imaging study

BACKGROUND:

Previous studies showed that compared with single-bundle (SB) precedures, double-bundle (DB) anterior cruciate ligament (ACL) reconstruction perform better.

OBJECTIVE:

To make assurance that distance of TT-TG may be altered along with ACL rupture and reconstruction.

METHODS:

Imaging study of 201 patients’s related cases by MRI and CT scans.

RESULTS:

Compared with the intact knee’s overall mean TT-TG value, the mean overall pre/postoperative TT-TG values showed a significant difference. For SB reconstruction, the mean pre/postoperative TT-TG values were 15.67± 2.46 mm and 14.72± 2.48 mm, respectively. Postoperative and intact knee TT-TG values were significantly different (p< 0.001). For DB reconstruction, the pre/postoperative mean TT-TG values were 15.11± 1.99 mm and 13.11± 1.71 mm. Postoperative and intact knee TT-TG values were not significantly different (p= 0.141).

CONCLUSIONS:

The increased TT-TG value from a ruptured ACL was significantly restored after ACL reconstruction. The TT-TG value after SB reconstruction was still obviously larger than that of the intact knee. It showed no significant difference between the postoperative TT-TG of the DB group and intact knees. The original TT-TG values of the knees were much closer to restoration after DB reconstruction.

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.

Outcomes of revision anterior cruciate ligament reconstruction secondary to reamer-irrigator-aspirator harvested bone grafting

INTRODUCTION

Patients with widened or misplaced tunnels may require bone grafting prior to revision anterior cruciate ligament (ACL) reconstruction. Utilising reamer-irrigator-aspirator (RIA) harvested bone from the femur showed promising filling rates. Nevertheless, the procedure has neither been validated in a larger population nor been assessed with regards to radiological and clinical outcome of the subsequently conducted revision ACL reconstruction. Therefore, the aim of this study was to evaluate tunnel filling rates, positioning of the revision tunnels and outcome parameters of such two-staged revision ACL reconstructions.

MATERIAL AND METHODS

A total of 15 consecutive patients were prospectively enrolled in this case series. CT scans were analysed before and after autologous RIA harvested bone grafting. Tunnel volumes and filling rates were calculated based on manual segmentation of axial CT scans. Revision ACL reconstruction was carried out after a mean interval of 6.2 months (±3.7) and positioning of the revision tunnels was assessed by plane radiographs. The mean follow-up was 19.8 months (±8.4) for objective evaluation and 37.1 months (±15.4) for patient reported outcomes. The clinical outcome was assessed by the quantification of the anterior tibial translation, the IKDC objective score, the Tegner activity scale and the Lysholm score.

RESULTS

Initial CT scans revealed mean tunnel volumes of 3.8cm³ (±2.7) femoral and 6.1cm³ (±2.4) tibial. Filling rates of 76.1% (±12.4) femoral and 87.4% (±5.9) tibial were achieved. Postoperative radiographs revealed significantly improved tunnel positioning with anatomical placement in all but one case at the femur and in all cases at the tibia. At follow up, patients showed significantly improved anterior tibial translations with residual side-to-side differences of 1.7 mm (±0.8) and significantly improved IKDC objective scores. Furthermore, significantly higher values were achieved on the Tegner activity scale (5.3 ± 1.4 vs. 2.8 ± 0.5) and the Lysholm score (85.4 ± 7.9 vs. 62.5 ± 10.5) compared to the preoperative status.

CONCLUSION

Autologous RIA harvested bone grafting ensures sufficient bone stock consolidation allowing for anatomical tunnel placement of the subsequently conducted revision ACL reconstruction. The two-staged procedure reliably restores stability and provides satisfying subjective and objective outcomes. Thus, RIA harvested bone grafting is an eligible alternative to autologous iliac crest or allogenic bone grafting.

Popliteal neurovascular bundle is safe during inside-out repair of medial meniscus without a safety incision

PURPOSE

There is a theoretical risk of injury to neurovascular structures during inside-out meniscal repair without a safety incision, although there are limited studies assessing this risk. This simulation study on archival MRI films was performed to assess the risk for the popliteal neurovascular bundle and the peroneal nerve during passage of needles for inside-out meniscus repair without a "safety incision", thereby defining a "safe zone" of the menisci that can be safely repaired using this technique.

METHODS

Archival MRI scans (n = 50) were retrieved and axial sections through the menisci were used for simulation. The needle passage was simulated for different points on the posterior horn and body of lateral and medial menisci at "half-hour" intervals using clock method (15° intervals) with three different portals and two different needle cannulas, resulting in six different scenarios of needle passage for each point on the meniscus. The distance of the needle in each scenario was measured from popliteal vessels (n = 50) and peroneal nerve (n = 10). The value "mean-3SD" was calculated for positive means and "Mean + 3SD" was calculated if the mean was negative. An additional 2 mm was defined as "safe distance". Thus, simulation models in which the mean - 3SD was less than 2 mm (or mean + 3SD was greater than - 2 mm for negative means) were labelled as "unsafe".

RESULTS

Needle passage through medial meniscus at and medial to 1 o'clock position for a right knee (or 11 o'clock position for a left knee) was safe, irrespective of the portal and needle type. For the lateral meniscus, only the equatorial region was found to be safe with this method.

CONCLUSIONS

The popliteal neurovascular bundle is safe during the inside-out medial meniscal repair without a safety incision. For the terminal-most part of the posterior horn, the AM portal and the straight cannula should be avoided. However, this method without safety incision cannot be recommended for lateral meniscus because of the risk to the popliteal vessels and the peroneal nerve. Instead, the inside-out method with a safety incision, or an all-inside method should be used for lateral meniscus.

LEVEL OF EVIDENCE

III.

Increased medial and lateral tibial posterior slopes are independent risk factors for graft failure following ACL reconstruction

PURPOSE

To analyze the contribution of increased lateral (LTPS) and medial tibial slopes (MTPS) as independent risk factors of graft failure following anterior cruciate ligament (ACL) reconstruction.

MATERIALS AND METHODS

Fifty-seven patients with graft failure after ACL reconstruction who underwent revision surgery between 2009 and 2014 were enrolled and matched to a control group of 69 patients with primary anatomic successful ACL reconstruction. Patients were matched based on age, sex, date of primary surgery and graft type. LTPS and MTPS were measured on MRI in a blinded fashion. Tibial and femoral tunnel positions were determined on CT scans. Independent t test was used to compare the MTPS and LTPS between subgroups. Risks of graft failure associated with an increasing MTPS and LTPS were analyzed using binary logistic analysis.

RESULTS

The means of LTPS (7.3°) and MTPS (6.7°) in the graft failure group were found to be significantly greater than in the control group (4.6° and 4.1°, respectively; p = < 0.001). Non-anatomic and anatomic tunnel positions were found in 42 cases (73.7%) and 15 cases (26.3%), respectively. There were no significant differences in MTPS or LTPS between patients with anatomic and non-anatomic tunnel positions within the graft failure group. An increase of the MTPS of 1° was associated with an 1.24 times increased likelihood of exhibiting graft failure [95% CI 1.07-1.43] (p = 0.003) and an increase of the LTPS of 1° was associated with an 1.17 times increased likelihood of exhibiting graft failure [95% CI 1.04-1.31] (p = 0.009). The increased risk was most evident in patients with a lateral tibial posterior slope of ≥ 10°.

CONCLUSIONS

Increased LTPS and MTPS are independent risk factors for graft failure following ACL reconstruction regardless whether tunnel position is anatomic or non-anatomic. This information may be helpful to clinicians when considering slope correction in selected revision ACL reconstruction procedures.

Differences between traumatic and non-traumatic causes of ACL revision surgery

PURPOSE

The purpose of this study was to evaluate and classify causes for anterior cruciate ligament (ACL) reconstruction failure. It was hypothesized that specific technical and biological reconstruction aspects would differ when comparing traumatic and non-traumatic ACL reconstruction failures.

MATERIALS AND METHODS

One hundred and forty-seven consecutive patients who experienced ACL reconstruction failure and underwent revision between 2009 and 2014 were analyzed. Based on a systematic failure analysis, including evaluation of technical information on primary ACL reconstruction and radiological assessment of tunnel positions, causes were classified into traumatic and non-traumatic mechanisms of failure; non-traumatic mechanisms were further sub-divided into technical and biologic causes. Spearman's rank correlation coefficient and chi-squared tests were performed to determine differences between groups based on various factors including graft choice, fixation technique, technique of femoral tunnel positioning, tunnel malpositioning, and time to revision.

RESULTS

Non-traumatic, i.e., technical, and traumatic mechanisms of ACL reconstruction failure were found in 64.5 and 29.1% of patients, respectively. Biological failure was found only in 6.4% of patients. Non-anatomical femoral tunnel positioning was found the most common cause (83.1%) for technical reconstruction failure followed by non-anatomical tibial tunnel positioning (45.1%). There were strong correlations between non-traumatic technical failure and femoral tunnel malpositioning, transtibial femoral tunnel drilling techniques, femoral transfixation techniques as well as earlier graft failure (p < 0.05).

CONCLUSIONS

Technical causes, particularly tunnel malpositioning, were significantly correlated with increased incidence of non-traumatic ACL reconstruction failure. Transtibial femoral tunnel positioning techniques and femoral transfixation techniques, showed an increased incidence of non-traumatic, earlier graft failure.

High incidence of partially anatomic tunnel placement in primary single-bundle ACL reconstruction

PURPOSE

The purpose of this study was to evaluate tunnel position and width in failed primary single-bundle (SB) anterior cruciate ligament (ACL) reconstructions. It was hypothesized that both femoral and tibial bone tunnels are frequently malplaced in terms of a partially anatomic position in the setting of failed SB ACL reconstruction.

METHODS

Patients with recurrent instability following isolated SB ACL reconstruction using hamstring tendon autografts, undergoing revision ACL surgery, were retrospectively included. Further inclusion criteria were age >18 years and availability of preoperative computed tomography (CT) scans and radiographs of the affected knee. Patients with multiligamentous instabilities as well as incomplete or poor radiographs were excluded. Tunnel position was evaluated according to the method described by Harner et al. and Stäubli and Rauschning. Tunnel width was determined on CT scans perpendicular to the bone tunnel axis at three different heights of each bone tunnel.

RESULTS

Eighty-two patients met the inclusion criteria and were considered for radiological analysis. Femoral tunnels were graded as anatomic in 60% (49 of 82) of all cases. In the remaining 40% (33/82), 27% of the tunnels were placed partially anatomic and 13% were graded as non-anatomic. Tibial tunnel placement was found to be anatomic in 54% (44/82) of all cases, partially anatomic in 45% and non-anatomic in 1% of the cases. No statistically significant difference between anatomic or partially anatomic tunnel position and tunnel diameter, neither for the femoral nor for the tibial side, was observed (n.s.).

CONCLUSION

The present study demonstrates that there is a high incidence of partially anatomic placed tunnels in failed SB ACL reconstruction. Tunnel width was not associated with tunnel position. Clinically, partially anatomic bone tunnels frequently require a staged procedure with bone grafting and subsequent ACL revision surgery. Thus, surgeons should carefully analyse tunnel position and width preoperatively to properly plan ACL revision surgery.

Variations in sagittal locations of anterior cruciate ligament tibial footprints and their association with radiographic landmarks: a human cadaveric study

Background

This cadaveric study aimed to demonstrate variation of the anterior cruciate ligament (ACL) tibial attachment in the sagittal plane, and to analyze the radiographic landmarks which predict the sagittal location of the ACL tibial attachment.

Methods

In 20 cadaveric knees, native ACLs were removed and the centers of the ACL tibial and femoral attachments were marked with metal pins. Full extension lateral radiographs were then obtained in each cadaveric knee. Using the full extension lateral radiographs, the sagittal location of the ACL tibial footprint center was estimated as a percentage in the Amis and Jakob’s line. Several radiographic landmarks including the geometry of Blumensaat’s line and the apex of the tibial eminence were measured. Then, the relationship between the variation of the sagittal location of the ACL tibial footprint and several radiographic landmarks were analyzed using Pearson’s correlation analysis.

Results

The average sagittal position of the native ACL tibial footprint was 40.9% (range: 38.0–45.0%). The line connecting the centers of the ACL footprint was nearly parallel to Blumensaat’s line, with an average angle of 1.7° (range: 0–4.1°). In addition, the distance from the point where Blumensaat’s line meets the tibial articular surface to the center of the ACL tibial footprint was almost consistent, at 7.6 mm on average (range: 6.4–8.7 mm). The correlation analysis revealed that the geometry of Blumensaat’s line was significantly correlated with the sagittal location of the ACL tibial footprint.

Conclusion

The radiographic landmark that showed a significant correlation with the ACL tibial footprint in the full extension lateral radiographs was Blumensaat’s line.

High non-anatomic tunnel position rates in ACL reconstruction failure using both transtibial and anteromedial tunnel drilling techniques

INTRODUCTION

Although it is well known from cadaveric and biomechanical studies that transtibial femoral tunnel (TT) positioning techniques are associated with non-anatomic tunnel positions, controversial data exist as so far no clinical differences could have been found, comparing transtibial with anteromedial techniques (AM). The purpose of the study was to analyze if graft failure following TT ACL reconstruction was more commonly associated with non-anatomic tunnel position in comparison with the AM technique. We hypothesized that, compared to AM techniques, non-anatomic tunnel positions correlate with TT tunnel positioning techniques.

MATERIALS AND METHODS

A total of 147 cases of ACL revision surgery were analyzed retrospectively. Primary ACL reconstructions were analyzed regarding the femoral tunnel drilling technique. Femoral and tibial tunnel positions were determined on CT scans using validated radiographic measurement methods. Correlation analysis was performed to determine differences between TT and AM techniques.

RESULTS

A total of 101 cases were included, of whom 64 (63.4%) underwent the TT technique and 37 (36.6%) the AM technique for primary ACL reconstruction. Non-anatomic femoral tunnel positions were found in 77.2% and non-anatomical tibial tunnel positions in 40.1%. No correlations were found comparing tunnel positions in TT and AM techniques, revealing non-anatomic femoral tunnel positions in 79.7 and 73% and non-anatomic tibial tunnel positions in 43.7 and 35.1%, respectively (p > 0.05).

CONCLUSIONS

Considerable rates of non-anatomic femoral and tibial tunnel positions were found in ACL revisions with both transtibial and anteromedial femoral drilling techniques. Despite the potential of placing tunnels more anatomically using an additional AM portal, this technique does not ensure anatomic tunnel positioning. Consequently, the data highlight the importance of anatomic tunnel positioning in primary ACL reconstruction, regardless of the applied drilling technique.

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."

ACL Roof Impingement Revisited: Does the Independent Femoral Drilling Technique Avoid Roof Impingement With Anteriorly Placed Tibial Tunnels?

Background:

Anatomic femoral tunnel placement for single-bundle anterior cruciate ligament (ACL) reconstruction is now well accepted. The ideal location for the tibial tunnel has not been studied extensively, although some biomechanical and clinical studies suggest that placement of the tibial tunnel in the anterior part of the ACL tibial attachment site may be desirable. However, the concern for intercondylar roof impingement has tempered enthusiasm for anterior tibial tunnel placement.

Purpose:

To compare the potential for intercondylar roof impingement of ACL grafts with anteriorly positioned tibial tunnels after either transtibial (TT) or independent femoral (IF) tunnel drilling.

Study Design:

Controlled laboratory study.

Methods:

Twelve fresh-frozen cadaver knees were randomized to either a TT or IF drilling technique. Tibial guide pins were drilled in the anterior third of the native ACL tibial attachment site after debridement. All efforts were made to drill the femoral tunnel anatomically in the center of the attachment site, and the surrogate ACL graft was visualized using 3-dimensional computed tomography. Reformatting was used to evaluate for roof impingement. Tunnel dimensions, knee flexion angles, and intra-articular sagittal graft angles were also measured. The Impingement Review Index (IRI) was used to evaluate for graft impingement.

Results:

Two grafts (2/6, 33.3%) in the TT group impinged upon the intercondylar roof and demonstrated angular deformity (IRI type 1). No grafts in the IF group impinged, although 2 of 6 (66.7%) IF grafts touched the roof without deformation (IRI type 2). The presence or absence of impingement was not statistically significant. The mean sagittal tibial tunnel guide pin position prior to drilling was 27.6% of the sagittal diameter of the tibia (range, 22%-33.9%). However, computed tomography performed postdrilling detected substantial posterior enlargement in 2 TT specimens. A significant difference in the sagittal graft angle was noted between the 2 groups. TT grafts were more vertical, leading to angular convergence with the roof, whereas IF grafts were more horizontal and universally diverged from the roof.

Conclusion:

The IF technique had no specimens with roof impingement despite an anterior tibial tunnel position, likely due to a more horizontal graft trajectory and anatomic placement of the ACL femoral tunnel. Roof impingement remains a concern after TT ACL reconstruction in the setting of anterior tibial tunnel placement, although statistical significance was not found. Future clinical studies are planned to develop better recommendations for ACL tibial tunnel placement.

Clinical Relevance:

Graft impingement due to excessively anterior tibial tunnel placement using a TT drilling technique has been previously demonstrated; however, this may not be a concern when using an IF tunnel drilling technique. There may also be biomechanical advantages to a more anterior tibial tunnel in IF tunnel ACL reconstruction.

Three-Dimensional CT Evaluation of Tunnel Positioning in ACL Reconstruction Using the Single Anteromedial Bundle Biological Augmentation (SAMBBA) Technique

BACKGROUND

Remnant preservation may confer important advantages in the anterior cruciate ligament (ACL)-reconstructed knee. However, the presence of a large remnant may obscure visualization and impair the ability to correctly place tunnels during surgery.

PURPOSE

To determine whether tunnel placement during anatomic ACL reconstruction using the single anteromedial bundle biological augmentation (SAMBBA) technique is consistent and precise when a large native remnant is preserved.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Included in this study were 99 patients undergoing an ACL reconstruction during which at least 50% of the native ACL was preserved. The femoral tunnel was created using an outside-in specific guide. The tibial tunnel was positioned in the anteromedial region of the ACL footprint, and the remnant was carefully preserved while drilling and passing the semitendinosus graft through it. Postoperatively, 3-dimensional computed tomography (3D CT) was used to evaluate tunnel placement. The mean tunnel locations were calculated and the standard deviation was used to evaluate precision of positioning. Inter- and intrareader agreement were determined to assess reliability of evaluation of tunnel position.

RESULTS

The center of the femoral tunnel was positioned at a mean 19.4% (SD, 2%) of the depth of the notch and a mean 23.1% (SD, 3.5%) of the lateral wall height. The center of the tibial tunnel was positioned at a mean 36.3% (SD, 3.8%) of the anteroposterior length of the tibial plateau and at a mean 47.0% (SD, 2.7%) of the mediolateral width. The small standard deviations demonstrate that this technique allows precise tunnel placement. The tunnel positions achieved were consistent with previous anatomic studies of femoral and tibial anteromedial bundle insertion. Intra- and interobserver reliability were high.

CONCLUSION

Three-dimensional CT evaluation demonstrated that despite the presence of a large remnant, placement of femoral and tibial tunnels for anatomic ACL reconstruction using the SAMBBA technique is consistent and precise.

The evaluation of muscle recovery after anatomical single-bundle ACL reconstruction using a quadriceps autograft

PURPOSE

The purpose of this study was to reveal the degree of muscle recovery and report the clinical results of anatomical single-bundle ACL reconstruction using a quadriceps autograft.

METHODS

Twenty subjects undergoing anatomical single-bundle ACL reconstruction using a quadriceps autograft were included in this study. A 5-mm-wide, 8-cm-long graft, involving the entire layer of the quadriceps tendon, was harvested without bone block. The average graft diameter was 8.1 ± 1.4 mm. An initial tension of 30 N was applied. The femoral tunnel was created from the far-medial portal. Each femoral and tibial tunnel was created close to the antero-medial bundle insertion site. For the evaluation of muscle recovery (quadriceps and hamstring), a handheld dynamometer was used. The evaluation of muscle recovery was performed pre-operatively, and at 3, 6, 9, and 12 months after surgery. Muscle recovery data were calculated as a percentage of leg strength in the non-operated leg. Anterior tibial translation (ATT), pivot shift test, and IKDC score were evaluated.

RESULTS

The average quadriceps strength pre-operatively, and at 3, 6, 9, and 12 months after ACL reconstruction was 90.5 ± 19, 67.8 ± 21.4, 84 ± 17.5, and 85.1 ± 12.6 %, respectively. The average hamstring strength pre-operatively, and at 3, 6, 9, and 12 months after ACL reconstruction was 99.5 ± 13.7, 78.7 ± 11.4, 90.5 ± 19, and 96.7 ± 13.8 %, respectively. ATT pre-operatively and at 12 months after surgery was 5.4 ± 1.3 and 1.0 ± 0.8 mm, respectively. No subjects exhibited positive pivot shift after surgery. Within 6 months following surgery, quadriceps hypotrophy was observed in all subjects. However, the hypotrophy had recovered at 12 months following surgery. No subjects complained of donor site pain after surgery.

CONCLUSION

Anatomical single-bundle ACL reconstruction using a quadriceps autograft resulted in equivalent level of muscle recovery and knee stability when compared with previously reported ACL reconstruction using hamstrings tendon with no donor site complications.

LEVEL OF EVIDENCE

Case controlled study, Level III.

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.

Increased revision rate with posterior tibial tunnel placement after using the 70-degree tibial guide in ACL reconstruction

PURPOSE

To map knee morphology radiographically in a population with a torn ACL and to investigate whether anatomic factors could be related to outcomes after ACL reconstruction at mid- to long-term follow-up. Further, we wanted to assess tibial tunnel placement after using the 70-degree "anti-impingement" tibial tunnel guide and investigate any relation between tunnel placement and revision surgery.

METHODS

Patients undergoing ACL reconstruction involving the 70-degree tibial guide from 2003 to 2008 were included. Two independent investigators analysed pre- and post-operative radiographs. Demographic data and information on revision surgery were collected from an internal database. Anatomic factors and post-operative tibial tunnel placements were investigated as predictors of revision.

RESULTS

Three-hundred and seventy-seven patients were included in the study. A large anatomic variation with significant differences between men and women was seen. None of the anatomic factors could be related to a significant increase in revision rate. Patients with a posterior tibial tunnel placement, defined as 50 % or more posterior on the Amis and Jakob line, did, however, have a higher risk of revision surgery compared to patients with an anterior tunnel placement (P = 0.03).

CONCLUSION

Use of the 70-degree tibial guide did result in a high incidence (47 %) of posterior tibial tunnel placements associated with an increased rate of revision surgery. The current study was, however, not able to identify any anatomic variation that could be related to a higher risk of revision surgery. Avoiding graft impingement from the femoral roof in anterior tibial tunnel placements is important, but the insight that overly posterior tunnel placement can lead to inferior outcome should also be kept in mind when performing ACL surgery.

LEVEL OF EVIDENCE

IV.