The Surgical Management of Tibial Spine Fractures in Children: A Survey of the Pediatric Orthopaedic Society of North America (POSNA)

Arthroscopic fixation techniques for tibial eminence fractures in pediatric patients: a review

The introduction of new internal fixation devices and arthroscopic techniques has led to significant changes in the surgical treatment of tibial eminence fractures (TEFs) in children. In recent years, arthroscopic surgery has arisen as the gold standard for the treatment of TEFs. This popularity of arthroscopic techniques has reduced surgical complications and improved patient prognosis. In this paper, we investigate the current situation of the use of arthroscopic fixation techniques for pediatric TEFs. We searched the PubMed database using the terms "arthroscopic treatment and tibial eminence," "arthroscopic treatment and tibial spine," "tibial eminence avulsion", "tibial spine fracture", with no limit on the year of publication. From these articles, we reviewed the use of various arthroscopic TEFs fixation techniques reported in the current literature. Overall, we found that the choice of fixation method seems to have no effect on clinical outcomes or imaging results. However, if an easy, strong fixation that is less prone to epiphyseal damage is desired, as a junior practitioner, the anchor technique should be mastered first, whereas for senior practitioners, a variety of fixation techniques for TEFs should be mastered, including anchors, sutures, and screws, so that personalized fixation can be achieved with the least amount of trauma, operative time, and complications. Higher quality studies are needed in the future to provide Useful evidence to determine the optimal fixation technique in terms of clinical outcomes, function, and complications.

Clinical and Functional Outcomes of Suture Versus Headless Screw Fixation for Tibial Eminence Fractures in Children

BACKGROUND

Suture and screw fixations are widely used to treat tibial eminence fractures (TEFs). Although a few biomechanical and clinical studies have compared suture fixation (SF) and screw fixation in the treatment of TEFs in children, no comparative clinical studies are available regarding headless screw fixation (HSF).

PURPOSE

To evaluate the clinical and functional outcomes of children with TEF who underwent SF and HSF.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

The study included 24 patients treated with either SF (11 patients) or HSF (13 patients) within 1 month of TEF (type 2 or 3) without associated ligamentous and bone injury between 2015 and 2020. All patients were evaluated at a minimum 2-year follow-up in terms of Lysholm score, Tegner activity level, International Knee Documentation Committee subjective score, and isometric strength test. Knee stability was compared based on the Lachman test, pivot-shift test, and KT-1000 arthrometer side-to-side difference.

RESULTS

No significant differences were found between the 2 groups in terms of Lysholm score, Tegner activity level, and International Knee Documentation Committee subjective score at follow-up. All patients were able to resume their daily activities within 6 months after the injury. However, flexion deficits (6°-10°) were found in 2 patients in the SF group and 1 patient in the HSF group, and extension deficits (3°-5°) were found in 3 patients in the SF group and 1 patient in the HSF group, without significant intergroup difference. Stability based on the Lachman test, pivot-shift test, and KT-1000 arthrometer side-to-side difference was also similar between the 2 groups at follow-up. No statistically significant difference was found between the 2 groups in isometric tests performed.

CONCLUSION

The present study is the first to compare the clinical and functional results of SF and HSF techniques. The HSF technique demonstrated comparable clinical and functional outcomes, suggesting its potential as an alternative to the SF technique.

Technical Note: Tibial Spine Avulsion Treatment with Arthroscopic Reduction and Internal Fixation with Kirschner Wires in Skeletally Immature Patients

INTRODUCTION

Tibial spine avulsion injury, tibial eminence injury, tibial spine fracture, and anterior cruciate ligament (ACL) avulsion are multiple terms that express the same pathological condition. It can be encountered both in the pediatric and adult population. A wide array of surgical techniques have been proposed to manage displaced tibial spine avulsions. Anyway, insufficient evidence is currently available to prefer one fixation technique over another, and a gold-standard arthroscopy-based technique is still missing. In this article, we describe a mini-invasive, safe and user-friendly technique for arthroscopic reduction and internal fixation of displaced tibial eminence fractures.

MATERIALS AND METHODS

Standard and patient-specific accessory arthroscopic portals allow for full access to knee visualization and management of concomitant intraarticular lesions. After performing the debridement of the inflammatory tissue and the release of eventual interposed tissues in the fracture site, the tibial eminence avulsion can be reduced by using a less-invasive bone impactor. With the knee flexed to 90°, the fracture fragments are then synthesized (under fluoroscopic control) with three thin Kirschner wires inserted in a proximal-distal direction in a cross-shaped geometry.

RESULTS

This technique allows a fast surgical and hospitalization time, a punctiform arthrotomy, proximal tibial physis preservation, and an early rehabilitation program.

CONCLUSIONS

This novel technique seems attractive and very promising since it is respectful of the epiphyseal growth plates and is thus suitable for children and adolescents.

Long-term Outcomes of Tibial Spine Avulsion Fractures After Open Reduction With Osteosuturing Versus Arthroscopic Screw Fixation: A Multicenter Comparative Study

Background

More information is needed regarding return to preinjury sport levels and patient-reported outcomes after tibial spine avulsion (TSA) fracture, which is most common in children aged 8 to 12 years.

Purpose

To analyze return to play/sport (RTP), subjective knee-specific recovery, and quality of life in patients after TSA fracture treated with open reduction with osteosuturing versus arthroscopic reduction with internal screw fixation.

Study Design

Cohort study; Level of evidence, 3.

Methods

This study included 61 patients <16 years old with TSA fracture treated via open reduction with osteosuturing (n = 32) or arthroscopic reduction with screw fixation (n = 29) at 4 institutions between 2000 and 2018; all patients had at least 24 months of follow-up (mean ± SD, 87.0 ± 47.1 months; range, 24-189 months). The patients completed questionnaires regarding ability to return to preinjury-level sports, subjective knee-specific recovery, and health-related quality of life, and results were compared between treatment groups. Univariate and multivariate logistic regression analyses were conducted to determine variables associated with failure to return to preinjury level of sport.

Results

The mean patient age was 11 years, with a slight male predominance (57%). Open reduction with osteosuturing was associated with a quicker RTP time than arthroscopy with screw implantation (median, 8.0 vs 21.0 weeks; P < .001). Open reduction with osteosuturing was also associated with a lower risk of failure to RTP at preinjury level (adjusted odds ratio, 6.4; 95% CI, 1.1-36.0; P = .035). Postoperative displacement >3 mm increased the risk of failure to RTP at preinjury level regardless of treatment group (adjusted odds ratio, 15.2; 95% CI, 1.2-194.9; P = .037). There was no difference in knee-specific recovery or quality of life between the treatment groups.

Conclusion

Open surgery with osteosuturing was a more viable option for treating TSA fractures because it resulted in a quicker RTP time and a lower rate of failure to RTP as compared with arthroscopic screw fixation. Precise reduction contributed to improved RTP.

Results of Anterior Cruciate Ligament Avulsion Fracture by Treatment Using Bioabsorbable Nails in Children and Adolescents

(1) Background: Anterior cruciate ligament avulsion fractures are characteristic for skeletally immature patients, and appropriate treatment is currently debated in the literature. The study aimed to evaluate the clinical and functional outcomes in patients with tibial eminence fractures treated with bioabsorbable nails in one orthopedic clinic. (2) Methods: After retrospective evaluation, we found 17 patients with tibial eminence fractures treated in orthopedic departments between January 2013 and July 2022 using bioabsorbable fixation nails. The study group comprised 12 boys and five girls aged 5 to 15.2 (average 10.1). The mean follow-up was 28 months. We diagnosed five type II fractures, ten type III fractures, and two type IV fractures according to Meyers-McKeever classification. (3) Results: We obtained a high healing rate-17 patients with the complete union on the control radiographs. We diagnosed two cases of malunion, of which one required revision surgery. Only one patient showed a slight anterior knee laxity. The treatment effect at follow-up was assessed using the Lysholm Knee Score and IKDC Score. The median Lysholm Score was 96.64 (SD 4.54), and the median IKDC Score was 84.64 (SD 3.10), which were both excellent results. (4) Conclusions: Based on our results, surgery using bioabsorbable devices for type II, III, and IV tibial eminence fractures in young individuals is an effective alternative, allowing good outcomes and restoring proper knee stability. The crucial factor for a good effect is a stable fracture fixation. Arthroscopic surgery gives good outcomes with minimal invasion. It is important not to prolong the attempts of arthroscopic reduction and to perform the open reduction to shorten the procedure's time and avoid complications.

What Are the Causes and Consequences of Delayed Surgery for Pediatric Tibial Spine Fractures? A Multicenter Study

Background:

The uncommon nature of tibial spine fractures (TSFs) may result in delayed diagnosis and treatment. The outcomes of delayed surgery are unknown.

Purpose:

To evaluate risk factors for, and outcomes of, delayed surgical treatment of pediatric TSFs.

Study Design:

Cohort study; Level of evidence, 3.

Methods:

The authors performed a retrospective cohort study of TSFs treated surgically at 10 institutions between 2000 and 2019. Patient characteristics and preoperative data were collected, as were intraoperative information and postoperative complications. Surgery ≥21 days after injury was considered delayed based on visualized trends in the data. Univariate analysis was followed by purposeful entry multivariate regression to adjust for confounders.

Results:

A total of 368 patients (mean age, 11.7 ± 2.9 years) were included, 21.2% of whom underwent surgery ≥21 days after injury. Patients who experienced delayed surgery had 3.8 times higher odds of being diagnosed with a TSF at ≥1 weeks after injury (95% CI, 1.1-14.3; P = .04), 2.1 times higher odds of having seen multiple clinicians before the treating surgeon (95% CI, 1.1-4.1; P = .03), 5.8 times higher odds of having magnetic resonance imaging (MRI) ≥1 weeks after injury (95% CI, 1.6-20.8; P < .007), and were 2.2 times more likely to have public insurance (95% CI, 1.3-3.9; P = .005). Meniscal injuries were encountered intraoperatively in 42.3% of patients with delayed surgery versus 21.0% of patients treated without delay (P < .001), resulting in 2.8 times higher odds in multivariate analysis (95% CI, 1.6-5.0; P < .001). Delayed surgery was also a risk factor for procedure duration >2.5 hours (odds ratio, 3.3; 95% CI, 1.4-7.9; P = .006). Patients who experienced delayed surgery and also had an operation >2.5 hours had 3.7 times higher odds of developing arthrofibrosis (95% CI, 1.1-12.5; P = .03).

Conclusion:

Patients who underwent delayed surgery for TSFs were found to have a higher rate of concomitant meniscal injury, longer procedure duration, and more postoperative arthrofibrosis when the surgery length was >2.5 hours. Those who experienced delays in diagnosis or MRI, saw multiple clinicians, and had public insurance were more likely to have a delay to surgery.

Does Insurance Status Affect Treatment of Children With Tibial Spine Fractures?

BACKGROUND

Previous studies have reported disparities in orthopaedic care resulting from demographic factors, including insurance status. However, the effect of insurance on pediatric tibial spine fractures (TSFs), an uncommon but significant injury, is unknown.

PURPOSE

To assess the effect of insurance status on the evaluation and treatment of TSFs in children and adolescents.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

We performed a retrospective cohort study of TSFs treated at 10 institutions between 2000 and 2019. Demographic data were collected, as was information regarding pre-, intra-, and postoperative treatment, with attention to delays in management and differences in care. Surgical and nonsurgical fractures were included, but a separate analysis of surgical patients was performed. Univariate analysis was followed by purposeful entry multivariate regression to adjust for confounding factors.

RESULTS

Data were collected on 434 patients (mean ± SD age, 11.7 ± 3.0 years) of which 61.1% had private (commercial) insurance. Magnetic resonance imaging (MRI) was obtained at similar rates for children with public and private insurance (41.4% vs 41.9%, respectively; P≥ .999). However, multivariate analysis revealed that those with MRI performed ≥21 days after injury were 5.3 times more likely to have public insurance (95% CI, 1.3-21.7; P = .02). Of the 434 patients included, 365 required surgery. Similar to the overall cohort, those in the surgical subgroup with MRI ≥21 days from injury were 4.8 times more likely to have public insurance (95% CI, 1.2-19.6; P = .03). Children who underwent surgery ≥21 days after injury were 2.5 times more likely to have public insurance (95% CI, 1.1-6.1; P = .04). However, there were no differences in the nature of the surgery or findings at surgery. Those who were publicly insured were 4.1 times more likely to be immobilized in a cast rather than a brace postoperatively (95% CI, 2.3-7.4; P < .001).

CONCLUSION

Children with public insurance and a TSF were more likely to experience delays with MRI and surgical treatment than those with private insurance. However, there were no differences in the nature of the surgery or findings at surgery. Additionally, patients with public insurance were more likely to undergo postoperative casting rather than bracing.

Pediatric Tibial Spine Fractures: Exploring Case Burden by Age and Sex

Background

Pediatric tibial spine fractures (TSFs) are a well-known clinical entity, but the epidemiology of these injuries is not fully understood. Further, there are limited data on outcomes after TSF treatment, specifically the proportion of patients requiring subsequent anterior cruciate ligament (ACL) reconstruction.

Purpose

To describe the distribution of TSF case burden by age and sex and to determine the proportion of patients undergoing subsequent ACL reconstruction or developing ACL insufficiency.

Study Design

Descriptive epidemiology study.

Methods

The Truven Health MarketScan database was queried to identify patients aged 7 to 18 years with TSFs between 2016 and 2018. Diagnosis and initial treatment (surgical vs nonoperative) were recorded based on database coding. Case burden by age and sex was calculated. The database, which includes longitudinal data, was then queried for subsequent diagnoses of ACL insufficiency as well as subsequent ACL reconstruction procedures performed among the patients.

Results

We found 876 cases of TSF, 71.3% of which were treated nonoperatively. The male to female ratio for case burden was 2.2:1. Cases peaked at age 13 to 14 years for boys and age 11 to 12 years for girls. Of all cases identified, 3.7% also had either a diagnosis code for ACL laxity entered in a delayed fashion into the database or a later procedure code for ACL reconstruction (considered together to represent "subsequent ACL insufficiency"). Only 15 subsequent ACL reconstructions (1.7% of cases) were found, all of which were among boys and 9 of which were among boys aged 13 to 14 years.

Conclusion

This longitudinal study is the largest epidemiological analysis of pediatric TSFs to date. We found low rates of subsequent ACL insufficiency and ACL reconstruction, with boys aged 13 to 14 years accounting for most of those cases. Rates of subsequent ACL reconstruction were lower than previously reported. Boys accounted for more than two times as many TSF cases as girls.

Arthroscopic Reduction and Internal Fixation of Tibial Eminence Fractures With Transosseous Suture Bridge Fixation

Arthroscopic reduction-internal fixation (ARIF) is an increasingly popular option for surgical management of displaced tibial eminence fractures. Although a variety of ARIF techniques have been described, anatomic reduction and stable fixation remain challenging. As a result, complications such as malunion, nonunion, anterior instability, arthrofibrosis, and hardware issues persist. In an effort to reduce complications and improve outcomes, modern suture-based ARIF techniques have been developed. However, the optimal technique and construct remain elusive. This article presents a technique for ARIF of tibial eminence fractures using a transosseous suture bridge construct with extracortical fixation. This technique uses a commercially available suture-passage device and meniscal root repair system for accurate tunnel placement, efficient suture management, and reliable fixation.

A Comparison of Nonoperative and Operative Treatment of Type 2 Tibial Spine Fractures

Background:

Tibial spine fractures (TSFs) are typically treated nonoperatively when nondisplaced and operatively when completely displaced. However, it is unclear whether displaced but hinged (type 2) TSFs should be treated operatively or nonoperatively.

Purpose:

To compare operative versus nonoperative treatment of type 2 TSFs in terms of overall complication rate, ligamentous laxity, knee range of motion, and rate of subsequent operation.

Study Design:

Cohort study; Level of evidence, 3.

Methods:

We reviewed 164 type 2 TSFs in patients aged 6 to 16 years treated between January 1, 2000, and January 31, 2019. Excluded were patients with previous TSFs, anterior cruciate ligament (ACL) injury, femoral or tibial fractures, or grade 2 or 3 injury of the collateral ligaments or posterior cruciate ligament. Patients were placed according to treatment into the operative group (n = 123) or nonoperative group (n = 41). The only patient characteristic that differed between groups was body mass index (22 [nonoperative] vs 20 [operative]; P = .02). Duration of follow-up was longer in the operative versus the nonoperative group (11 vs 6.9 months). At final follow-up, 74% of all patients had recorded laxity examinations.

Results:

At final follow-up, the nonoperative group had more ACL laxity than did the operative group (P < .01). Groups did not differ significantly in overall complication rate, reoperation rate, or total range of motion (all, P > .05). The nonoperative group had a higher rate of subsequent new TSFs and ACL injuries requiring surgery (4.9%) when compared with the operative group (0%; P = .01). The operative group had a higher rate of arthrofibrosis (8.9%) than did the nonoperative group (0%; P = .047). Reoperation was most common for hardware removal (14%), lysis of adhesions (6.5%), and manipulation under anesthesia (6.5%).

Conclusion:

Although complication rates were similar between nonoperatively and operatively treated type 2 TSFs, patients treated nonoperatively had higher rates of residual laxity and subsequent tibial spine and ACL surgery, whereas patients treated operatively had a higher rate of arthrofibrosis. These findings should be considered when treating patients with type 2 TSF.

Complications and Controversies in the Management of 5 Common Pediatric Sports Injuries

Growing participation in sports among children, along with increasingly intense training regimens, has contributed to an increasing rate of sports-related injuries. Despite the similarities to adult sports injuries, pediatric patients have distinctive injury patterns because of the growing physis and therefore necessitate unique treatment algorithms. Caring for these injured children requires in-depth knowledge of not only pediatric injury patterns, but also the scope of age-specific treatments, the associated complications, and the controversies. When treating motivated pediatric athletes, one must be able to strike a delicate balance between patients' eagerness to return to sport and the need to ensure their long-term health and function. Knowledge of controversies and complications will help both patients and physicians make informed decisions about how best to restore pediatric athletes back to health.

Good Subjective Outcomes, Stable Knee and High Return to Sport after Tibial Eminence Avulsion Fracture in Children

Avulsion fracture of the tibial spine (TSA) is uncommon in children, although its incidence is increasing with the earlier practice of competitive sport activities. This study aims to report mid to long term outcomes in children who sustained a TSA, with a special focus on a return to sport activities. Skeletally immature patients with a TSA, treated in two orthopedic hospitals, were evaluated for range of motion and knee laxity using KT1000, KiRA and Rolimeter. The pediatric International Knee Documentation Committee score (Pedi-IKDC) and the Hospital for Special Surgery pediatric Functional Activity Brief Scale (Pedi-FABS) questionnaires were recorded during the latest visit. Forty-two children were included. Twenty-six were treated nonoperatively and 16 underwent surgery. At a mean follow-up of 6.9 ± 3.6 years, 36 patients completed the questionnaires and 23 patients were tested with arthrometers. Among them, 96% had normal knee laxity. The Pedi-IKDC score averaged 96.4 ± 5.7 points, while the mean Pedi-FABS was 22.2 ± 5.9 points, without statistically significant differences between groups. Twenty-eight patients (78%) returned to their previous level of sport activity (eight amateur, 13 competitive, seven elite athletes). Eight patients (22%) quit sport, mostly because of re-injury fear. If properly treated, pediatric TSAs achieve a high rate of successful healing, with complete restoration of knee stability and an early return to sport activities.

Pediatric tibial eminence fracture treatment: A case series using a bioabsorbable screw

BACKGROUND

Pediatric tibial eminence fractures constitute a complex injury with multiple treatment options. We have described a technique that combines direct visualization through an open approach and stable fixation using a bioabsorbable screw. The purpose of this study is to describe our surgical technique for tibial eminence fractures and to compare the radiographic and functional outcomes to previous open or arthroscopic methods.

METHODS

We retrospectively reviewed a series of five pediatric patients who underwent open reduction and internal fixation of a tibial eminence fracture with a headless, bioabsorbable poly-L lactic acid (PLLA) screw (Bio-Compression screw, Arthrex Inc, Naples, FL) from 2016 to 2017. The surgical technique involves an open approach, direct fracture reduction, and fixation with a PLLA screw without violating the epiphyseal plate. Postoperative assessment was quantified using the Lysholm knee score (LKS), knee arc of motion (AOM), presence of a pivot shift or Lachman, and knee radiographs with an average of 18.4 months of follow-up.

RESULTS

Five patients (average age of 11.3 years) were treated with a biobsorbable screw and followed for an average of 18.4 months. Average LKS was 99.6, AOM was 98.4%, all patients had negative pivot shift and Lachman exams, and all patients went on to radiographic union. No patients required re-operation or implant removal.

CONCLUSIONS

The goals of tibial eminence fracture management are fracture union, restoring knee stability, and regaining normal knee motion and kinematics. Our study demonstrates that open treatment with a bioabsorbable screw is an excellent alternative surgical method as it reliably results in rigid fixation, fracture union, excellent knee function scores, and it mitigates the possible need for hardware removal.

LEVEL OF EVIDENCE

Therapeutic Level IV - Case series.

Diagnostic and treatment preferences for developmental dysplasia of the hip: a survey of EPOS and POSNA members

PURPOSE

The aim of this study was to elucidate developmental dysplasia of the hip (DDH) diagnosis and treatment preferences among members of the Pediatric Orthopaedic Society of North America (POSNA) and European Paediatric Orthopaedic Society (EPOS).

METHODS

A 54-question survey on DDH diagnosis and treatment preferences was distributed to POSNA and EPOS members. Descriptive statistics were performed.

RESULTS

A total of 459 responses were analyzed. Ultrasound was the preferred modality for diagnosing DDH in infants less than six months old; few surgeons preferred radiographs. In all, 57% of POSNA members had radiology technicians perform ultrasounds, only 7% of EPOS members did. The percent coverage defining a dislocated hip varied greatly, the most frequent response being < 20% for POSNA and < 40% for EPOS members. Pavlik harnesses were the most popular harness/brace, used by 90% of POSNA and 71% of EPOS members. POSNA members were more likely than EPOS members to use a rigid abduction brace following initial harness/brace failure. For residual acetabular dysplasia, POSNA members were twice as likely as EPOS members to institute hip abduction bracing. Most surgeons would not perform closed reduction at less than three months of age or open reduction at less than six months of age. Most EPOS -members used traction prior to reduction; few POSNA members did. Few POSNA and EPOS members believed that reduction should be delayed until the ossific nucleus was visible.

CONCLUSION

There is great variation in the preferred methods for diagnosing and treating DDH. This survey is the largest transcontinental survey to compile diagnostic and treatment preferences for DDH. With wide variations in practice, there is room for quality improvement.

Management of a type two avulsion fracture of the tibial intercondylar eminence in children: arthroscopic suture fixation versus conservative immobilization

BACKGROUND

Treatment of a type II tibial eminence avulsion fracture was controversial. The aim of this study was to compare the clinical outcomes of a modified arthroscopic suture fixation versus conservative immobilization in treatment of this type fracture in immature population.

METHODS

A total of 43 type II avulsion fractures of tibial intercondylar eminence in immature patients were retrospectively enrolled in the study. Twenty-two (13 males, 9 females) were treated with arthroscopic suture fixation and 21(12 males, 9 females) with conservative cast immobilization. Radiograph, Lachman test, anterior drawer test (ADT), International Knee Documentation Committee (IKDC) 2000 subjective score, and Lysholm score were used to evaluate clinical outcomes in follow-up.

RESULT

All 43 paediatric or adolescent patients with a mean of 11.3 years (range, 8-16 years) were followed up for a median period of 34.5 months (range, 24-46 months). Radiographic evaluation showed optimal reduction immediately after surgery and bone union within three months. At the final follow-up, no limitation of knee motion range was found in any children. Grade II laxity was found in one case from surgical group and six from conservation group, showing significant difference based on ADT (χ2 = 7.927, P = 0.005) and Lachman tests (χ2 = 9.546, P = 0.002). IKDC and Lysholm scores were significantly improved; however, there were significant differences in the IKDC score (91.7 ± 4.34 vs. 84.7 ± 6.11, t = 4.35, P < 0.001) and Lysholm score (93.4 ± 4.04 vs. 87.1 ± 5.24, t = 4.53, P < 0.001), and the improvement of IKDC value (40.2 ± 7.83 vs. 31.4 ± 8.4, t = 3.57, P = 0.001) and Lysholm value (43.8 ± 6.55 vs. 35.4 ± 5.97, t = 4.36, P < 0.001) between the surgical group and the nonsurgical group.

CONCLUSION

In treatment of type II tibial eminence avulsion fracture, a modified, 8 shape suture fixation under arthroscopy showed superior clinical outcomes than nonsurgical immobilization in term of restoring the laxity of paediatric ACL.