Arthroscopic primary repair of the anterior cruciate ligament: what the radiologist needs to know

Approaching expert-level accuracy for differentiating ACL tear types on MRI with deep learning

Treatment for anterior cruciate ligament (ACL) tears depends on the condition of the ligament. We aimed to identify different tear statuses from preoperative MRI using deep learning-based radiomics with sex and age. We reviewed 862 patients with preoperative MRI scans reflecting ACL status from Hunan Provincial People's Hospital. Based on sagittal proton density-weighted images, a fully automated approach was developed that consisted of a deep learning model for segmenting ACL tissue (ACL-DNet) and a deep learning-based recognizer for ligament status classification (ACL-SNet). The efficacy of the proposed approach was evaluated by using the sensitivity, specificity and area under the receiver operating characteristic curve (AUC) and compared with that of a group of three orthopedists in the holdout test set. The ACL-DNet model yielded a Dice coefficient of 98% ± 6% on the MRI datasets. Our proposed classification model yielded a sensitivity of 97% and a specificity of 97%. In comparison, the sensitivity of alternative models ranged from 84 to 90%, while the specificity was between 86 and 92%. The AUC of the ACL-SNet model was 99%, demonstrating high overall diagnostic accuracy. The diagnostic performance of the clinical experts as reflected in the AUC was 96%, 92% and 88%, respectively. The fully automated model shows potential as a highly reliable and reproducible tool that allows orthopedists to noninvasively identify the ACL status and may aid in optimizing different techniques, such as ACL remnant preservation, for ACL reconstruction.

The Anterior Cruciate Ligament: Principles of Treatment

The anterior cruciate ligament (ACL) is a crucial connective tissue in the knee joint (tibiofemoral joint). Although the surgical anatomy of this ligament has been studied and interpreted for decades, it remains a topic of discussion among surgeons. The ACL has two bundles, the anteromedial (AM) and the posterolateral (PL) bundle. ACL tears are among the most frequently sustained injuries to the tibiofemoral joint. The ACL is an important rotational stabilizer of the knee joint. The human knee joint can be classified as a complex structure, as it has many ligaments supporting its stability and ensuring required joint mobility. Previously, the outcomes of primary ACL surgery were poor; however, with time, the modalities have improved substantially. There are two methods of performing the reconstruction procedure, the single-bundle method, in which only the AM bundle is reconstructed, and the double-bundle method, in which both the AM and PL bundles of the ACL are reconstructed. Double bundle arthroscopic ACL reconstruction has been recognized as the gold standard procedure. The grafts used for the reconstruction procedure are the tendon of the patella graft and the grafts of the hamstrings. However, one of the drawbacks of performing this surgery is the development of complications, like osteoarthritis. This complication is observed majorly in sports professionals. This article aims to sum up the anatomy of the ACL, its regular tears, the various surgical aspects of managing it, and the advancement of treatment options in the past centuries. Although much has been achieved, detailed scientific studies should be carried out to improve the prognosis and decrease the risk of development of complications.

MR Imaging of Acute Knee Injuries: Systematic Evaluation and Reporting

Acute knee injury ranges among the most common joint injuries in professional and recreational athletes. Radiographs can detect joint effusion, fractures, deformities, and malalignment; however, MR imaging is most accurate for radiographically occult fractures, chondral injury, and soft tissue injuries. Using a structured checklist approach for systematic MR imaging evaluation and reporting, this article reviews the MR imaging appearances of the spectrum of traumatic knee injuries, including osteochondral injuries, cruciate ligament tears, meniscus tears and ramp lesions, anterolateral complex and collateral ligament injuries, patellofemoral translation, extensor mechanism tears, and nerve and vascular injuries.

Anterior cruciate ligament repair with internal brace augmentation: A systematic review

BACKGROUND

Primary repair of anterior cruciate ligament (ACL) ruptures has re-emerged as a treatment option for proximal tears, with internal brace augmentation often utilised. The aim of this study is to provide an overview of the current evidence presenting outcomes of ACL repair with internal bracing to assess the safety and efficacy of this technique.

METHODS

All studies reporting outcomes of arthroscopic primary repair of proximal ACL tears, augmented with internal bracing from 2014-2021 were included. Primary outcome was failure rate and secondary outcomes were subjective patient reported outcome measures (PROMs) and objective assessment of anteroposterior knee laxity.

RESULTS

Nine studies were included, consisting of 347 patients, mean age 32.5 years, mean minimum follow up 2 years. There were 36 failures (10.4%, CI 7.4% - 14.1%). PROMs reporting was variable across studies. KOOS, Lysholm and IKDC scores were most frequently used with mean scores > 87%. The mean Tegner and Marx scores at follow-up were 6.1 and 7.8 respectively. The mean side to side difference measured for anteroposterior knee laxity was 1.2mm.

CONCLUSIONS

This systematic review with meta-analysis shows that ACL repair with internal bracing is a safe technique for treatment of proximal ruptures, with a failure rate of 10.4%. Subjective scores and clinical laxity testing also revealed satisfactory results. This suggests that ACL repair with internal bracing should be considered as an alternative to ACL reconstruction for acute proximal tears, with the potential benefits of retained native tissue and proprioception, as well as negating the need for graft harvest.

The Reliability of Classifying the Morphology of Anterior Cruciate Ligament Remnants during Surgery

Arthroscopic classification of the torn anterior cruciate ligament (ACL) morphology is fundamental for clinical studies on emerging techniques such as repair and preservation. At present, the most acknowledged classification is Crain description of four morphological patterns. The purpose of the study was to analyze the intra- and interobserver reliability of Crain classification in patients undergoing ACL reconstruction surgeries. The study included 101 patients who had ACL reconstruction surgery between the years 2014 and 2017. The morphological pattern of ACL remnant scar formation during surgery was observed and classified according to Crain by three orthopaedic surgeons. Inter- and intraobserver reliabilities were measured using kappa statistics. Intraobserver reliability for the Crain classification ranged from 0.63 to 0.83 (substantial to almost perfect agreement). Interobserver reliability was 0.51 (moderate agreement). In almost a third of the cases, observers reported on additional morphological pattern of scar formation that was not well defined by Crain. A modified classification of four patterns was suggested: (A) without scar tissue, (B) with adhesion to the femoral notch (wall or roof), (C) with adhesion to the notch and posterior cruciate ligament (PCL), and (D) with adhesion to the PCL. Reanalysis of these four morphological configurations resulted in interobserver reliability of 0.82 (almost perfect agreement). In conclusion, the Crain classification of torn ACL remnant morphology has moderate interobserver reliability; however, a suggested classification with modified and additional configurations has almost perfect reliability and may be useful for studies on ACL repair and preservation.

Accuracy of magnetic resonance imaging in predicting anterior cruciate ligament tear location and tear degree

Purpose

The purpose of this study is to evaluate the reliability of magnetic resonance imaging (MRI) in predicting the location of ACL tears in preoperative planning for anterior cruciate ligament (ACL) repair.

Methods

Thirty-four patients who underwent ACL repair were retrospectively analyzed to compare intraoperative arthroscopic findings with preoperative MRIs.

Results

For identifying type I tears, the sensitivity of MRI was 9.0% and the accuracy of MRI was 8.8%. There was moderate interrater agreement between MRI findings for tear location and tear degree.

Conclusion

MRI alone may not necessarily be accurate in identifying which ACL tears are amenable to repair.

Study design

Retrospective case series; Level of Evidence: IV.

Postoperative Knee and Shoulder

Arthroscopic surgery in the knee most commonly addresses ligament, meniscal, or articular cartilage abnormalities. Similarly, arthroscopic surgery of the shoulder most commonly addresses tendon and labral abnormalities. The expected postoperative MRI findings depend on both the procedure performed and the time since surgery. Identifying complications and failed procedures relies on both clinical and imaging evaluations.

Sports Imaging of Team Handball Injuries

Team handball is a fast high-scoring indoor contact sport with > 20 million registered players who are organized in > 150 federations worldwide. The combination of complex and unique biomechanics of handball throwing, permitted body tackles and blocks, and illegal fouls contribute to team handball ranging among the four athletic sports that carry the highest risks of injury. The categories include a broad range of acute and overuse injuries that most commonly occur in the shoulder, knee, and ankle. In concert with sports medicine, physicians, surgeons, physical therapists, and radiologists consult in the care of handball players through the appropriate use and expert interpretations of radiography, ultrasonography, CT, and MRI studies to facilitate diagnosis, characterization, and healing of a broad spectrum of acute, complex, concomitant, chronic, and overuse injuries. This article is based on published data and the author team's cumulative experience in playing and caring for handball players in Denmark, Sweden, Norway, Germany, Switzerland, and Spain. The article reviews and illustrates the spectrum of common handball injuries and highlights the contributions of sports imaging for diagnosis and management.

Good to Excellent Functional Short-Term Outcome and Low Revision Rates Following Primary Anterior Cruciate Ligament Repair Using Suture Augmentation

The aim of this study was to evaluate the functional outcome of primary anterior cruciate ligament (ACL) repair using suture augmentation (SA) in 93 consecutive patients (67 female) with a minimum follow-up of 12 months. Patients’ outcomes were determined using International Knee Documentation Committee (IKDC) score, Lysholm score (LS) and Tegner score (TS). Knee-laxity was assessed using the KT-1000 arthrometer. Eighty-eight patients (67 female, mean age 42 years ± standard deviation (SD) 13) were available for follow-up after a mean time of 21 months (range 12–39). Three patients (3%) underwent revision surgery and were excluded from functional analysis. The mean IKDC score was 87.4 ± 11, mean LS was 92.6 ± 11, mean pre-traumatic TS was 6 ± 2 and mean postoperative TS was 6 ± 2, with a mean difference (TS_Diff) of 1 ± 1. The interval from injury to surgery had no significant impact on the postoperative IKDC (p = 0.228), LS (p = 0.377) and TS_Diff (p = 0.572). Patients’ age (>40 years), BMI (>30) and coexisting ligament or meniscal injuries did not seem to influence postoperative functional results. Primary ACL repair using SA provides good to excellent functional outcomes with a low probability of revision surgery at a minimum of 12 months.

The healing potential of an acutely repaired ACL: a sequential MRI study

Background

Recently, there has been renewed interest in primary anterior cruciate ligament (ACL) repair. The aim of this study is to report early clinical and radiological results of a consecutive series of acute ACL tears treated with arthroscopic primary ACL repair within 14 days from injury.

Patients and methods

A consecutive series of patients with acute ACL tears were prospectively included in the study. Based on MRI appearance, ACL tears were classified into five types, and tissue quality was graded as good, fair, and poor. Patients with type I, II, and III tears and at least 50% of ACL tibial remnant intact with good tissue quality were ultimately included. Clinical outcomes were measured using the Tegner Lysholm Knee Scoring Scale (TLKSS), the Knee Injury and Osteoarthritis Outcome Score (KOOS), subjective and objective International Knee Documentation Committee (IKDC) scores, and KT-1000. Patients were also followed up with MRI evaluations at 1, 3, and 6 months postoperatively. ACL appearance was graded based on morphology (normal or abnormal) and signal intensity (isointense, intermediate, and hyperintense).

Results

The mean TLKSS was 98.1, the mean subjective IKDC was 97.6, and the mean KOOS was 98.2. The objective IKDC score was A in eight of ten patients and B in two patients. KT-1000 measurements showed a maximum manual side-to-side difference of less than 2 mm in eight of ten patients, whereas two patients showed a difference of 3 mm. The morphology of the repaired ACL was normal (grade 1) at 1 month follow-up in ten of ten cases, and this appearance persisted at 3 and 6 months postoperatively. The signal intensity at 1 month postoperatively was graded as isointense (grade 1) in four of ten patients, intermediate (grade 2) in five of ten patients, and hyperintense (grade 3) in one of ten patients. At both 3 and 6 months postoperatively, the signal intensity was graded as isointense (grade 1) in nine of ten patients and intermediate (grade 2) in one of ten patients.

Conclusions

Arthroscopic primary ACL repair performed acutely in a carefully selected group of patients with proximal ACL tears and good tissue quality showed good early clinical and radiological results.

Level of evidence

Level 4.

Efficacy and Tolerability of Progen, a Nutritional Supplement Based on Innovative Plasma Proteins, in ACL Reconstruction: A Multicenter Randomized Controlled Trial

Background:

New biologic strategies are arising to enhance healing and improve the clinical outcome of anterior cruciate ligament (ACL) reconstruction.

Purpose:

To evaluate the efficacy of a new oral nutritional supplement (Progen) that contains hydrolyzed collagen peptides and plasma proteins, a hyaluronic acid–chondroitin sulfate complex, and vitamin C.

Study Design:

Randomized controlled trial; Level of evidence, 2.

Methods:

The study included patients who underwent ACL reconstruction with hamstring autografts using the same fixation method. All patients received the same analgesia and physical therapy (PT) protocol and were randomized to receive either the nutritional supplement (supplemented group) or no additional therapy (control group). Patients were followed up at days 7, 30, 60, and 90. Pain was assessed by use of a visual analog scale (VAS) and by analgesic consumption. Clinical outcome was assessed via International Knee Documentation Committee (IKDC) score and the number of PT sessions. Perceived efficacy and tolerability were rated on a 5-point Likert scale. Graft maturation was assessed by a blinded musculoskeletal radiologist using magnetic resonance imaging. The number of adverse events (AEs) was recorded.

Results:

The intention-to-treat analysis included 72 patients, 36 allocated to the supplemented group and 36 to the control group, with no significant differences regarding demographic and preoperative characteristics. Both groups showed significant improvement in pain and function (measured by VAS and IKDC scores) during the 90-day follow-up period (P < .001 for both), without significant differences between groups. The supplemented group had fewer patients that needed analgesics (8.5% vs 50.0%; P < .05) and attended fewer PT sessions (38.0 vs 48.4 sessions; P < .001) at 90 days and had a higher IKDC score at 60 days (62.5 vs 55.5; P = .029) compared with the control group. Patient- and physician-perceived efficacy was considered significantly higher in the supplemented group at 60 and 90 days (P < .05). Perceived tolerability of the overall intervention was better in the supplemented group at 30, 60, and 90 days (P < .05). Graft maturation showed more advanced degrees (grades 3 and 4) in the supplemented group at 90 days (61.8% vs 38.2%; P < .01). No intolerance or AEs associated with the nutritional supplement treatment were reported.

Conclusion:

The combination of the nutritional supplement and PT after ACL reconstruction improved pain, clinical outcome, and graft maturation. Nutritional supplementation showed higher efficacy during the second month of recovery, without causing AEs.

Registration:

NCT03355651 (ClinicalTrials.gov identifier).

Anterior cruciate ligament repair - past, present and future

Background

This article provides a detailed narrative review on the history and current concepts surrounding ligamentous repair techniques in athletic patients. In particular, we will focus on the anterior cruciate ligament (ACL) as a case study in ligament injury and ligamentous repair techniques. PubMed (MEDLINE), EMBASE and Cochrane Library databases for papers relating to primary anterior cruciate ligament reconstruction were searched by all participating authors. All relevant historical papers were included for analysis. Additional searches of the same databases were made for papers relating to biological enhancement of ligament healing.

Current standard

The poor capacity of the ACL to heal is one of the main reasons why the current gold standard surgical treatment for an ACL injury in an athletic patient is ACL reconstruction with autograft from either the hamstrings or patella tendon. It is hypothesised that by preserving and repairing native tissues and negating the need for autograft that primary ACL repair may represent a key step change in the treatment of ACL injuries.

History of primary ACL repair

The history of primary ACL repair will be discussed and the circumstances that led to the near-abandonment of primary ACL repair techniques will be reviewed.

New primary repair techniques

There has been a recent resurgence in interest with regards to primary ACL repair. Improvements in imaging now allow for identification of tear location, with femoral-sided injuries, being more suitable for repair. We will discuss in details strategies for improving the mechanical and biological environment in order to allow primary healing to occur.

In particular, we will explain mechanical supplementation such as Internal Brace Ligament Augmentation and Dynamic Intraligamentary Stabilisation techniques. These are novel techniques that aim to protect the primary repair by providing a stabilising construct that connects the femur and the tibia, thus bridging the repair.

Bio enhanced repair

In addition, biological supplementation is being investigated as an adjunct and we will review the current literature with regards to bio-enhancement in the form platelet rich plasma, bio-scaffolds and stem cells. On the basis of current evidence, there appears to be a role for bio-enhancement, however, this is not yet translated into clinical practice.

Conclusions

Several promising avenues of further research now exist in the form of mechanical and biological augmentation techniques. Further work is clearly needed but there is renewed interest and focus for primary ACL repair that may yet prove the new frontier in ligament repair.