Evaluation of a magnesium ring device for mechanical augmentation of a ruptured ACL: Finite element analysis

BACKGROUND

Recently, a ring device was used for mechanical augmentation to aid the healing of ACL. In-vivo study using goat showed improved joint stability after ring repair in comparison to using biological augmentation alone. Objective of this study was to quantify the load and stress levels in the ACL and its femoral insertion site following ring repair.

METHODS

A three dimensional finite element model of a goat stifle joint was developed to find the load and stress level in the ACL and at its femoral insertion site following ring repair.

FINDINGS

Ring repair led to approximately a 50% reduction in anterior-posterior tibial translation over the model with a deficient ACL: 5.2 mm vs 10.6 mm, 4.4 mm vs 9.0 mm, and 2.9 mm vs 5.2 mm at joint flexion angles of 37°, 60° and 90° respectively. After ring repair, the in situ force in the ACL was restored to be nearly 60% of the intact ACL. The maximum Von Mises stress at the femoral insertion site was up to 71% of those for the intact ACL.

INTERPRETATION

This study offers new knowledge on the function of a ring device to mechanically augment ACL repair in order to improve its healing. Quantitative data on loading levels in the repaired ACL and its insertion site that led to its healing could be used as basis for developing novel devices to mechanically augment the healing of ACL in humans.

The anatomy of the anterolateral structures of the knee - A histologic and macroscopic approach

BACKGROUND

The anatomy of the anterolateral structures of the knee is complex and still controversial. The aim of our study was to analyze this anatomy by histologic and macroscopic evaluation, with a particular emphasis on the anterolateral ligament (ALL).

MATERIAL AND METHODS

Twenty-three cadaveric knee joints were dissected followed by a qualitative and quantitative anatomic analysis of the anterolateral knee structures. Histology and comparison of different anterolateral structures was performed in addition.

RESULTS

The ALL was identified in all of the dissected cadaveric knee specimens. It runs in an oblique course from its proximo-dorsal insertion at the distal femur into a ventro-distal direction to the anterolateral tibia. The femoral insertion site was found to be posterior and slightly proximal to the lateral femoral epicondyle and the femoral attachment of the lateral collateral ligament (LCL). The femoral insertion of the ALL overlapped the LCL in all dissected knees. The tibial insertion site was midway between Gerdy's tubercle (GT) and the tip of the fibular head (FH). In 15 of the dissected 23 knee joints, thin attachments to the lateral meniscus were observed. Histology confirmed differences in the composition of the anterolateral knee joint capsule, the ALL and the iliotibial band (ITB).

CONCLUSIONS

The ALL occurs as a regular separate anterolateral ligamentous structure. It is distinguishable from the ITB and the anterolateral joint capsule in both embalmed and non-embalmed specimens. Histology of the ALL indicates typical ligamentous tissue which clearly differs from the anterolateral knee joint capsule and the thicker ITB.

LEVEL OF EVIDENCE

Level II, descriptive anatomic study.

Classification of gait muscle activation patterns according to knee injury history using a support vector machine approach

Abnormal muscle activation patterns during gait following knee injury that persist past the acute injury and rehabilitation phase (>three years) are not well characterized but may be related to post-traumatic knee osteoarthritis. The aim was to characterize the abnormal muscle activity from electromyograms of five leg muscles that were recorded during treadmill walking for young adults with and without a previous knee injury 3-12 years prior. The wavelet transformed and amplitude normalized electromyograms yielded intensity patterns that reflect the muscle activity of these muscles resolved in time and frequency. Patterns belonging to the affected or unaffected leg in previously injured participants and patterns belonging to a previously injured vs. uninjured participant were grouped and then classified using a principal component analysis followed by a support vector machine. A leave-one-out cross-validation was used to test the model significance and generalization. The results showed that trained classifiers could successfully recognize whether muscle activation patterns belonged to the affected or unaffected leg of previously injured individuals. Classification rates of 83% were obtained for all subjects, 100% for females only, indicating sex-specific knee injury effects. In contrast, it was not possible to discriminate between patterns belonging to the previously injured legs or dominant legs of control subjects. For females, the injured leg showed a stronger muscle activity for hamstring muscles and a lower activity for the vastus lateralis. In conclusion, systematic knee injury effects on the neuromuscular control of the knee during gait were present 3-12 years later.

A comparative study of the epiligament of the medial collateral and the anterior cruciate ligament in the human knee. Immunohistochemical analysis of collagen type I and V and procollagen type III

BACKGROUND

Recent reports in rat models have shown that fibroblasts in the epiligament, an enveloping tissue of the ligament, are not static cells and play an important role during the early ligament healing of isolated grade III injury of the collateral ligaments of the knee. Fibroblasts produce collagen types I, III and V and infiltrate within the ligament body via the endoligament. In addition, similarities have been reported between the structure of the epiligament of the medial collateral ligament and anterior cruciate ligament of the knee in rat and in human. In line with the ascribed role of the epiligament tissue and the synthesis of these collagens and their role in ligament healing, the aim of this study was to determine their presence in the normal epiligament of the aforementioned ligaments in humans, to compare their differential expression and to present a novel hypothesis about the failure of healing of the anterior cruciate ligament in contrast to the medial collateral ligament.

MATERIALS AND METHODS

We used samples from the mid-substance of the medial collateral and the anterior cruciate ligament of the knee joint, acquired from 12 fresh knee joints. Routine histological analysis was performed through hematoxylin and eosin stain, Mallory's trichrome stain and Van Gieson's stain. The immunohistochemical analysis was conducted using monoclonal antibodies against collagen type I and V and procollagen type III. The number of cells in the epiligament, endoligament and the ligament tissue was assessed quantitatively through a computerized system for image analysis NIS-Elements Advanced Research and Statistica software.

RESULTS

Our observations revealed certain differences in the morphology of the epiligament, as well as variations in the expression of the investigated molecules. Expression of collagen type I was mostly low-positive (1+) in the epiligament and positive (2+) in the ligament tissue of both ligaments. Expression of procollagen type III was mostly positive (2+) in the epiligament and ligament tissue of the medial collateral ligament, low-positive (1+) in the epiligament and negative (0) in ligament tissue of the anterior cruciate ligament. Expression of collagen type V was predominantly low-positive (1+) in the epiligament and negative (0) in the ligament tissue of both ligaments. The immunoreactivity for all three molecules was always higher in the epiligament of the medial collateral ligament than that of the anterior cruciate ligament.

CONCLUSIONS

The results of our study illustrate for the first time that fibroblasts in the human epiligament are indeed responsible for the synthesis of the main types of collagen participating in the early ligament healing, thus corresponding to previous data of the medial collateral ligament healing in animal models. The differences between the epiligament of the investigated ligaments could add a novel explanation for the failed anterior cruciate ligament healing.

Increased risk of ACL revision with non-surgical treatment of a concomitant medial collateral ligament injury: a study on 19,457 patients from the Swedish National Knee Ligament Registry

PURPOSE

To determine how concomitant medial collateral ligament (MCL) and lateral collateral ligament (LCL) injuries affect outcome after anterior cruciate ligament (ACL) reconstruction.

METHODS

Patients aged > 15 years who were registered in the Swedish National Knee Ligament Registry for primary ACL reconstruction between 2005 and 2016 were eligible for inclusion. Patients with a concomitant MCL or LCL injury were stratified according to collateral ligament treatment (non-surgical, repair or reconstruction), and one isolated ACL reconstruction group was created. The outcomes were ACL revision and the 2-year Knee Injury and Osteoarthritis Outcome Score (KOOS), which were analyzed using univariable and multivariable Cox regression and an analysis of covariance, respectively.

RESULTS

A total of 19,457 patients (mean age 27.9 years, 59.4% males) met the inclusion criteria. An isolated ACL reconstruction implied a lower risk of ACL revision compared with presence of a non-surgically treated MCL injury (HR = 0.61 [95% CI 0.41-0.89], p = 0.0097) but not compared with MCL repair or reconstruction. A concomitant LCL injury did not impact the risk of ACL revision. Patients with a concomitant MCL or LCL injury reported inferior 2-year KOOS compared with isolated ACL reconstruction. The largest difference was found in the sports and recreation subscale across all groups, with MCL reconstruction resulting in the maximum difference (14.1 points [95% CI 4.3-23.9], p = 0.005).

CONCLUSION

Non-surgical treatment of a concomitant MCL injury in the setting of an ACL reconstruction may increase the risk of ACL revision. However, surgical treatment of the MCL injury was associated with a worse two-year patient-reported knee function. A concomitant LCL injury does not impact the risk of ACL revision compared with an isolated ACL reconstruction.

LEVEL OF EVIDENCE

Cohort study, Level III.

Device-assisted tensioning is associated with lower rates of graft failure when compared to manual tensioning in ACL reconstruction

PURPOSE

To describe (1) the current graft tensioning practices in ACL reconstruction (ACLR) and, (2) the failure rates with the use of manual tensioning, or device-assisted tensioning at the time of graft fixation.

METHODS

The electronic databases MEDLINE, EMBASE, and PubMed were searched independently by two reviewers from database inception to search date on January 21, 2017. Inclusion criteria were studies reporting graft tensioning method and rate of graft failure. The definition of graft failure used was: (1) side-to-side instrumented laxity > 5 mm, (2) Lachman 2 +, (3) positive pivot-shift testing, (4) MRI-confirmed graft rupture or, (5) need for revision surgery.

RESULTS

A total of 3379 patients and 3380 knees were treated with ACL reconstruction and followed for an average of 41.7 months (range 4-145 months). ACLR with manual tensioning was performed on 1518 (51.9%) patients and device-assisted tensioning was performed on 1802 (48.1%) patients. The average knee position reported was 29.2° in single-bundle ACLR and 22.9° in double-bundle ACLR. The median amount of tension used in manual tensioning was 'maximum manual tension' and 50 N in device-assisted tensioning. Overall, the failure rate in studies reporting manual tensioning was 8.9% compared to 4.3% in device-assisted tensioning.

CONCLUSION

Both manual tensioning and device-assisted tensioning are associated with low overall failure rates (< 10%) in ACLR; however, there is a higher rate of reported failure with manual tensioning compared to device-assisted tensioning. These findings highlight the need to investigate variations in graft tensioning practice, such as specific tension devices and their parameters, with high-quality, randomized controlled trials to elucidate details of their clinical impact.

LEVEL OF EVIDENCE

Level IV, systematic review of level I-IV studies.

Effect of wearing a knee brace or sleeve on the knee joint and anterior cruciate ligament force during drop jumps: A clinical intervention study

BACKGROUND

Knee braces are considered to be extremely useful tools in reducing the shear force of knee joints for non-contact anterior cruciate ligament (ACL) injury prevention. However, the effectiveness of sports knee braces and sleeves remains to be identified. Therefore, the purpose of this study was to evaluate the effectiveness of wearing commercialized sports knee braces and sleeves on knee kinematics, kinetics, and ACL force during drop jumps using musculoskeletal modeling analysis.

METHODS

Musculoskeletal modeling analysis was conducted on 19 male alpine skiers who performed drop jump motions from a 40-cm box under three conditions: without a brace/sleeve, with a brace, and while wearing a neoprene sleeve.

RESULTS

The physical performance (i.e., the center of mass of the jumping height) was not affected by the type of brace or sleeve. However, wearing a brace or sleeve during drop jump tasks reduced the knee joint's maximum flexion, abduction angles, and adduction moment. The knee joint shear force when wearing the brace or sleeve exhibited no statistical differences. Further, the ACL load estimated in this study did not exhibit any statistical differences in relation to wearing a brace or sleeve.

CONCLUSIONS

The knee braces and sleeves reduced flexion and abduction movement, and adduction moment but did not reduce the knee joint shear force, internal rotation moment, or the ACL force. Therefore, if a sports knee brace that controls the knee joint's shear force and internal rotation moment is developed, it may aid in preventing ACL injuries.

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.

Quantitative correlation of mechanoreceptors in tibial remnant of ruptured human anterior cruciate ligament with duration of injury and its significance: an immunohistochemistry-based observational study

BACKGROUND

Proprioception is a specialized sensory modality encompassing the movement of the joint and its position in space. Reconstruction of the anterior cruciate ligament (ACL) does not always yield expected outcome, suggesting that successful reconstruction depends on not only the ultimate strength of the graft but also recovery of proprioception. Treatment delay is a significant concern in developing countries, e.g., in Asia. Thus, presence of mechanoreceptors is one of the factors having paramount importance for successful outcome. We conducted this study to identify mechanoreceptors via immunohistochemical staining and correlate their presence with duration of injury.

MATERIALS AND METHODS

A total of 38 injured native ACL stumps were harvested from patients undergoing ACL reconstruction and stained with neurofilament protein stain to detect functional mechanoreceptors.

RESULTS

Of the specimens, 44.7% stained positive for monoclonal antibody. No association was found between duration of injury and presence of mechanoreceptors (p = 0.897). No correlation was seen between age and side.

CONCLUSIONS

No correlation was found between duration of injury and presence of viable mechanoreceptors, hence it is beneficial to preserve the native ACL stump irrespective of the time interval between injury and surgery.

LEVEL OF EVIDENCE

III.

Self-reported functional recovery after reconstruction versus repair in acute anterior cruciate ligament rupture (ROTOR): a randomized controlled clinical trial

BACKGROUND

Anterior cruciate ligament (ACL) reconstruction is today's surgical gold standard for ACL rupture. Although it provides satisfactory results, not all patients return to their previous activity level and moreover, early posttraumatic osteoarthritis is not prevented. As such, a renewed interest has emerged in ACL suture repair combined with dynamic augmentation. Compared to ACL reconstruction, the hypothesized advantages of ACL suture repair are earlier return to sports, reduction of early posttraumatic osteoarthritis and preservation of the patient's native ACL tissue and proprioceptive envelope of the knee. In recent literature, ACL suture repair combined with dynamic augmentation tends to be at least equally effective compared to ACL reconstruction, but no randomized comparative study has yet been conducted.

METHODS/DESIGN

This study is a prospective, stratified, block randomized controlled trial. Forty-eight patients with an ACL rupture will be assigned to either a suture repair group with dynamic augmentation and microfracture of the femoral notch, or an ACL reconstruction group with autologous semitendinosis graft and all-inside technique. The primary objective is to investigate the hypothesis that suture repair of a ruptured ACL results in at least equal effectiveness compared with an ACL reconstruction in terms of patient self-reported outcomes (IKDC 2000 subjective scale) 1 year postoperatively. Secondary objectives are to evaluate patient self-reported outcomes (IKDC 2000, KOOS, Tegner, VAS), re-rupture rate, rehabilitation time required for return to daily and sports activities, achieved levels of sports activity, clinimetrics (Rolimeter, LSI, Isoforce) and development of osteoarthritis, at short term (6 weeks, 3, 6 and 9 months and 1 year), midterm (2 and 5 years) and long term (10 years) postoperatively.

DISCUSSION

A renewed interest has emerged in ACL suture repair combined with dynamic augmentation in the treatment of ACL rupture. Recent cohort studies show good short- and midterm results for this technique. This randomized controlled trial has been designed to compare the outcome of suture repair of a ruptured ACL, combined with DIS as well as microfracture of the femoral notch, with ACL reconstruction using autologous semitendinosus.

TRIAL REGISTRATION

Clinical Trials Register NCT02310854 (retrospectively registered on December 1st, 2014).

Comparison of outcome after ACL reconstruction in terms of subjective assessment of symptoms and function and clinical assessment of ligament stability

BACKGROUND

The knee joint is frequently involved in sports and other injuries with Anterior cruciate ligament being a very common ligament to be injured. The Lachman test, pivot-shift test, and instrumented knee laxity examination are frequently used and reported for evaluation of ACL reconstruction. The aim of this study is to examine and evaluate the relationships between the clinical assessment of ligament stability and subjective assessment of symptoms and function after ACL reconstruction.

METHODS

A total of 50 young and middle aged patients with unilateral knee ACL injury treated with ACL reconstruction using hamstring graft were evaluated for a minimum period of 1 year. Clinical assessment of ligament stability was done through Lachman and pivot-shift examination. Subjective variables of symptoms at follow-up included pain, swelling, instability and locking of knee. Subjective function at follow up included satisfaction with outcome, squatting, ascending or descending stairs, jumping, twisting and Lysholm score.

RESULTS

Lachman Examination at follow-up had no significant (P > .05) relationship with pain, swelling, instability, locking, squatting, ascending or descending stairs, jumping, twisting, satisfaction with outcome and Lysholm score. Pivot-shift examination at follow-up had significant associations with patient satisfaction (P = .04), instability of knee (P = .02), difficulty during twisting (P = .02) and Lysholm score (P = .01).

CONCLUSION

Pivot-shift examination is a better measure than Lachman examination or instrumented knee laxity as far as patients' functional outcome and overall satisfaction is concerned.

Factors influencing the success of anterior cruciate ligament repair with dynamic intraligamentary stabilisation

PURPOSE

Primary repair of the anterior cruciate ligament (ACL) has regained interest of clinicians with recent development of novel repair techniques. Dynamic intraligamentary stabilisation was introduced in an attempt to promote healing by shielding cyclic loads acting upon the ACL during the healing phase. The aim of this study was to identify negative factors likely to influence success of this procedure.

METHODS

Between 2009 and 2014, 264 patients with an acute ACL rupture undergoing dynamic intraligamentary stabilisation were included in this study. Patients were evaluated for anterior/posterior laxity; range of motion and patient reported outcome measures. Adverse events and re-operations were noted. Failure was defined as AP Translation >3 mm, re-rupture or conversion to ACL reconstruction. Minimum follow-up was 24 months. Univariate and multivariate regression models were utilized to determine predictors of failure.

RESULTS

An overall complication rate of 15.1% was noted comprising 9.5% (n = 25) re-ruptures, 4.1% (n = 11) persistent instability, and 1.5% (n = 4) > 10° fixed flexion deformity. Two factors were identified as negative predictors of failure: (1) pursuit of competitive sport activities with a Tegner pre-injury score >7 (Odds Ratio (OR) 4.4, CI 1.2-15.9, p = 0.02) and (2) mid-substance ACL rupture location (OR 2.5, 1.1-5.7, p = 0.02). When neither of those risk factors occurred the failure rate was limited to 3.9%.

CONCLUSIONS

Correct patient selection and narrowing of indications are necessary to maintain high success rates of the procedure. Mid-substance ACL ruptures and a high pre-injury sports activity level are two predictors of inferior outcome.

LEVEL OF EVIDENCE

II.

Primary single suture anchor re-fixation of anterior cruciate ligament proximal avulsion tears leads to good functional mid-term results: a preliminary study in 12 patients

Background

Current studies demonstrate encouraging short-term results after primary anterior cruciate ligament (ACL) suture anchor repair. However, earlier studies reported deterioration of knee function at 5-year follow-up following good clinical short-term recovery. Therefore, the aim of this study was to evaluate clinical long-term results after primary ACL repair at a minimum 5-year follow-up.

Methods

In a retrospective study, 13 patients were included between 2009 and 2012. Inclusion criteria were an acute proximal, femoral avulsion tear of the ACL with good tissue quality and sagittal instability in a healthy, demanding patient. Patients suffering proximal tibial fractures, arthrosis, or multiligamentous injuries of the knee were excluded. The ACL was anchored to the footprint by a single 2.9-mm push lock anchor, followed by additional microfracturing. For follow-up, patients were evaluated according to Lysholm score, modified Cincinnati score, and Tegner activity score. Clinical examination was performed using Lachman and pivot-shift testing and range of motion and sagittal stability measurement, using a Rolimeter.

Results

Mean follow-up was 79 (range 60 to 98) months. One patient was lost to follow-up, and 11 out of 12 patients were examined clinically. Eight patients achieved good subjective and clinical outcome. One patient suffered an early re-tear, and one patient with additional patellar tendon tear and one patient with polyarthritis demonstrated poor subjective and clinical results due to lasting instability. Seven out of 12 patients reached preoperative Tegner activity score postoperatively again. The mean Lysholm score was 85.3 points, mean subjective IKDC score was 87.3 points, and mean modified Cincinnati score was 83.8 points. Rolimeter measurements demonstrated a mean side-to-side difference of 2 (range 1–5) mm.

Conclusion

In the current study, primary surgical re-fixation of proximal, femoral ACL avulsion tears using single suture anchor repair resulted in good to excellent clinical mid-term outcomes. However, in cases of additional serious damage to extensor structures or systemic rheumatic disease, loss of function and unsatisfying clinical results occurred. Further prospective randomized controlled trials are necessary to confirm the encouraging long-term results of this study.

Trial registration

Bavarian National Medical Chamber of Physicians, file number 2016-095. German Clinical Trials (DRKS00013059)

Anterolateral Ligament Reconstruction or Extra-Articular Tenodesis: Why and When?

Residual rotational laxity following anterior cruciate ligament (ACL) reconstruction has been identified as significant concern in many patients, despite evolution of techniques. The expanding body of knowledge on the anatomy and biomechanics of the anterolateral soft tissue restraints in rotational control of the knee has reignited an interest in extra-articular reconstruction techniques for augmenting ACL reconstruction. Reconstruction techniques currently used can be broadly categorized as either lateral extra-articular tenodesis or reconstruction of the anterolateral ligament. In this article, we outline the relevant anatomy, biomechanics, and rationale behind the indications and technique of our current extra-articular augmentation procedure.

In vivo mechanical behaviour of the anterior cruciate ligament: A study of six daily and high impact activities

The anterior cruciate ligament (ACL) plays a key role in the stability of the knee joint restricting the rotation and anterior tibial translation. However, there is a lack of knowledge of the in vivo ACL mechanical behaviour during high impact manoeuvres. The motion of 12 young participants with healthy knees was captured while they performed the following activities: walking, running, cross-over cutting, sidestep cutting, jumping and jumping with one leg. The in vivo ACL length and strain were estimated using experimental kinematic data and three degree of freedom (DOF) knee model. The in vivo ACL tensile forces were determined with a well-established force/strain relationship obtained through ACL tensile tests. Statistical regression models between ACL length with respect to angles for each activity have been performed in order to better understand the ACL failure mechanisms. The maximum ACL tensile force was observed during jumping vertically at maximum effort with two legs (1.076±0.113 N/BW). Surprisingly, the peak tensile ACL force for all subjects during crossover cutting (0.715±0.2647 N/BW) was lower than during walking (0.774±0.064 N/BW). Regression coefficients for crossover cutting indicated that excessive knee rotation and abduction angles contribute more significantly to the ACL elongation than in activities such as walking or running. These findings suggested that the ACL is subjected to multidirectional loading; further studies will be performed to investigate torsion, tensile and shear force on the ligament.

Arthroscopic fixation of pediatric tibial eminence fractures using suture anchors: a mid-term follow-up

PURPOSE

The aim of this study was to follow a group of skeletally immature patients who received arthroscopy-assisted fixation of the displaced tibial eminence fractures with suture anchors and evaluate the clinical results.

METHODS

Twenty-one pediatric patients with displaced tibial eminence fractures were enrolled in this retrospectively study. They received arthroscopy-assisted reduction and fixation using suture anchors. All cases were followed up for 40-47 months with a mean of 43.4 months. Follow-up examinations included radiographic assessment, Lysholm score, Tegner score, International Knee Documentation Committee (IKDC) rating scale and KT-1000 test.

RESULT

Twenty patients were available for our final evaluations. They improved significantly at the final follow-up compared with preoperative examinational results with respect to the results of radiographic assessment, Lysholm score, Tegner score, IKDC rating scale and KT-1000 test.

CONCLUSION

Arthroscopy-assisted reduction and fixation of the displaced tibial eminence fractures using suture anchors is a simple and reliable technique and is suitable for skeletally immature patients.

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.

Orthobiologics in Pediatric Sports Medicine

Orthobiologics are biological substances that allow injured muscles, tendons, ligaments, and bone to heal more quickly. They are found naturally in the body; at higher concentrations they can aid in the healing process. These substances include autograft bone, allograft bone, demineralized bone matrix, bone morphogenic proteins, growth factors, stem cells, plasma-rich protein, and ceramic grafts. Their use in sports medicine has exploded in efforts to increase graft incorporation, stimulate healing, and get athletes back to sport with problems including anterior cruciate ligament ruptures, tendon ruptures, cartilage injuries, and fractures. This article reviews orthobiologics and their applications in pediatric sports medicine.

ACL Injury Prevention: What Does Research Tell Us?

PURPOSE OF REVIEW

Mechanisms leading to anterior cruciate ligament (ACL) injury have been identified, yet re-injury or a secondary injury persists in the athletic population. The purpose of this review is to identify risk factors associated with ACL injury and investigate programs to prevent injury.

RECENT FINDINGS

Faulty mechanics during dynamic movement that cause excessive valgus force at the knee increases the risk of ACL injury. Faulty mechanics may be a result of lateral displacement of the trunk, unequal limb loading, and lack of control to avoid the valgus knee position. Altered movements that place the ACL at risk are best identified in a fatigued state; however, could be recognized in a standard dynamic assessment. The faulty movement patterns are modifiable and should be addressed in an injury prevention program. Prevention programs include various modes of exercise such as plyometrics, neuromuscular training, and strength training. This review concludes that those programs which utilize neuromuscular training and strength training at a young age show the most promise in reducing ACL injuries. An ongoing thorough dynamic examination is necessary for all athletes while adjusting the intervention program in order to decrease the risk of ACL injury.

In vivo posterior cruciate ligament elongation in running activity after anatomic and non-anatomic anterior cruciate ligament reconstruction

PURPOSE

The goals of this study were to (1) investigate the in vivo elongation behaviour of the posterior cruciate ligament (PCL) during running in the uninjured knee and (2) evaluate changes in PCL elongation during running after anatomic or non-anatomic anterior cruciate ligament (ACL) reconstruction.

METHODS

Seventeen unilateral ACL-injured subjects were recruited after undergoing anatomic (n = 9) or non-anatomic (n = 8) ACL reconstruction. Bilateral high-resolution CT scans were obtained to produce 3D models. Anterolateral (AL) and posteromedial (PM) bundles insertion sites of the PCL were identified on the 3D CT scan reconstructions. Dynamic knee function was assessed during running using a dynamic stereo X-ray (DSX) system. The lengths of the AL and PM bundles were estimated from late swing through mid-stance. The contralateral knees served as normal controls.

RESULTS

Control knees demonstrated a slight decrease in AL bundle and a significant decrease in PM bundle length following foot strike. Length and elongation patterns of the both bundles of the PCL in the anatomic ACL reconstruction group were similar to the controls. However, the change in dynamic PCL length was significantly greater in the non-anatomic group than in the anatomic reconstruction group after foot strike (p < 0.05).

CONCLUSION

The AL bundle length decreased slightly, and the PM bundle length significantly decreased after foot strike during running in uninjured knees. Anatomic ACL reconstruction maintained normal PCL elongation patterns more effectively than non-anatomic ACL reconstruction during high-demand, functional loading. These results support the use of anatomic ACL reconstruction to achieve normal knee function in high-demand activities.

LEVEL OF EVIDENCE

Case-control study, Level III.

A study of isokinetic strength and laxity with and without anterior cruciate ligament injury

[Purpose] The purpose of this study was to provide useful information for future treatments and to organize rehabilitation programs for anterior cruciate ligament injury by assessing isokinetic muscle strength and laxity of knee joints in athletes with anterior cruciate ligament injuries. [Subjects and Methods] Thirty-one high school athletes with anterior cruciate ligament injuries participated in this study. Isokinetic muscle strength at 60°/sec and anterior cruciate ligament laxity for non-involved and involved sides, classified on the basis of the severity of anterior cruciate ligament injury, were assessed. [Results] A comparison of isokinetic muscle strength measured from the non-involved and involved sides showed a significant difference in the maximum strength and knee flexor muscle strength. For laxity, a significant difference was observed in the anterior drawer test results obtained with a force of 88 N. [Conclusion] In conclusion, this study has shown that the assessment of isokinetic muscle strength and ligament laxity from athletes with anterior cruciate ligament injury should be utilized to provide baseline data for prevention and prediction of injury.

Validation of varus stress radiographs for anterior cruciate ligament and posterolateral corner knee injuries: A biomechanical study

PURPOSE

The purpose of this study was to determine the effect of isolated anterior cruciate ligament (ACL) insufficiency on the radiographic varus stress test, and to provide reference data for the increase in lateral compartment opening under varus stress for a combined ACL and PLC injury.

METHODS

Ten cadaveric lower extremities were fixed to a jig in 20° of knee flexion. Twelve Newton-meter (Nm) and clinician-applied varus loads were tested, first with intact knee ligaments, followed by sequential sectioning of the ACL, fibular collateral ligament (FCL), popliteus tendon and the popliteofibular ligament (PFL). Lateral compartment opening was measured after each sequential sectioning.

RESULTS

Maximum increase in lateral compartment opening for an isolated ACL deficient knee was 1.06mm with mean increase of 0.52mm (p=0.021) for the clinician-applied load. Mean increase in lateral compartment opening in an ACL and FCL deficient knee compared to the intact knee was 1.48mm (p<0.005) and 1.99mm (p<0.005) for the 12-Nm and clinician-applied loads, respectively, increasing to 1.94mm (p<0.005) and 2.68mm (p<0.005) with sectioning of the ACL and all PLC structures.

CONCLUSIONS

Anterior cruciate ligament deficiency contributes to lateral compartment opening on varus stress radiographs though not sufficiently to confound previously established standards for lateral ligament knee injuries. We did not demonstrate the same magnitude of lateral compartment opening with sectioning of the PLC structures as previously reported, questioning the reproducibility of varus stress radiographic testing among institutions. Clinicians are cautioned against making surgical decisions based solely on current standards for radiographic stress examinations.

Can an expansion device be used in anterior cruciate ligament reconstruction? An in vitro study of soft tissue graft tibial fixation

BACKGROUND

The purpose of this study was to compare the mechanical properties of an interference screw with an expansion device in anterior cruciate ligament (ACL) reconstruction.

METHODS

A total of 52 porcine tibia and 20 polyurethane foam blocks (0.16g/cm³) were used. Forty pullout tests were carried out to combine the two types of bones - surrogate and porcine - with the two fixation systems: interference screw and expansion device (n=10 per group). Thirty-two cyclic tests (n=8 per group) were carried out with both fixation devices in porcine bone at two different force amplitudes (100N and 200N).

RESULTS

Stiffness and load values (mean±SD) at six millimeters of displacement for the expansion device and the interference screw were 74±33N/mm, 318±135N, and 52±28N/mm, 205±70N, respectively, showing a difference in stiffness (P=0.016) and load at six millimeters of displacement (P=0.001). No correlation between insertion torque and the ultimate failure load was found for both fixation devices tested. In cyclic tests, significantly higher (P<0.001) numbers of cycles (mean±SD) were reached with the expansion device (81,014±30,291 at 100N; 13,462±11,351 at 200N) than with the interference screw (15,100±8623 at 100N; 343±113 at 200N) at six millimeters of displacement.

CONCLUSION

The use of an expansion device for ACL reconstructions seemed to be a promising alternative to an interference screw. Insertion torque alone was not a useful predictor of graft fixation strength in ACL reconstructions.

Surgical Management and Treatment of the Anterior Cruciate Ligament/Posterolateral Corner Injured Knee

Posterolateral knee injuries occur more commonly than in the past. These injuries most commonly occur concurrent with cruciate ligament tears. The main stabilizers of the posterolateral knee are the fibular collateral ligament, the popliteus tendon, and the popliteofibular ligament. These static stabilizers function to prevent increased varus, external rotation, and coupled posterolateral rotation of the knee. The most important clinical tests to diagnose posterolateral knee injuries are the varus stress test, posterolateral drawer, and dial tests. Varus stress radiographs are key objective means to diagnose these injuries. Anatomic- based reconstructions have been validated to restore stability and improve outcomes.

Long term results of bone-patella-tendon-bone ACL reconstruction

BACKGROUND

To assess outcomes of bone-patella-tendon-bone ACL-reconstruction at 18 years follow-up.

MATERIAL AND METHODS

Outcome measures included the IKDC clinical examination form and clinical scores. Radiographs were analyzed to determine the grade of osteoarthritis.

RESULTS

69% of the examined patients (n = 54) had a normal/nearly normal knee, 14% were abnormal and 17% severely abnormal with significant improvement (P ≤ 0.001). The mean Lysholm score was 87.7 ± 12.4 and the Tegner activity level was 5 ± 2. Osteoarthritic changes were present in 52%.

CONCLUSION

BPTB ACL-reconstruction provides a satisfactory outcome with a high incidence of radiographic osteoarthritic changes.