Anterior cruciate ligament injury in children
Acute knee injury is caused by contact trauma (fall or traffic accident) or by non-contact trauma (distortion, sports injury). Up to the age of 13, knee injuries are equally common in boys and girls, and 2x more often in boys above the age of 13. The majority of injuries occur during sports activities. The increased participation in sports activities by increasingly younger children has led to an increase in the number of traumatic knee injuries in the past 10 years. Anterior cruciate ligament (ACL) injuries are relatively rare in children, totaling < 5% of all ACL injuries. Most children with this injury are 9 years or older.
Children with knee injuries often experience problems because they are usually very active. In the treatment of cruciate ligament injuries, a distinction is made between children who have stopped growing (closed growth plates) and children who are still growing (open growth plates). This can be assessed on an X-ray of the knee.
Skeletal Age and Growth Plates
Around the knee are the two main growth plates of the body, responsible for the vast majority of growth in height. The (sports) injuries in and around the knee area are different in children than in adults because the growth plates are a weak link in the movement chain; they offer less resistance to impact than the hard bone and strong ligaments of the knee. The growth plate at the end of the thigh bone (distal femoral epiphysis) is the largest and fastest growing growth plate in the body, accounting for 70% of the femur and 40% of the length of the leg. The growth plate in the upper part of the tibia (proximal tibial epiphysis) contributes 55% to the length of the tibia and 25% of the total leg length. On average, these two growth plates provide 1 cm and 0.6 cm growth in length per leg per year, respectively. The growth plates close at the age of 14-16 years in girls and 16-18 years in boys. The calendar age does not always correspond to the skeletal age (= potential residual growth of the child). Skeletal age is determined in the Netherlands by taking an X-ray of the hand. Damage to these growth plates (due to trauma or surgery) can therefore have major consequences for height growth, especially in a younger child. Skeletal age is determined in the Netherlands by taking an X-ray of the hand. Damage to these growth plates (due to trauma or surgery) can therefore have major consequences for height growth, especially in a younger child. Skeletal age is determined in the Netherlands by taking an X-ray of the hand. Damage to these growth plates (due to trauma or surgery) can therefore have major consequences for height growth, especially in a younger child.
Children with open growth plates (still growing) are at risk for a growth disorder of the leg during ACL surgery. Children with closed growth plates can be treated like adults. However, they are more likely to have a new ACL tear after surgery compared to adults. More on this later.
Anterior cruciate ligament (ACL) injuries in children
There are 2 types of ACL injuries in children: eminent fractures (bone fracture at attachment of ACL to tibia) and ligament injuries (tearing of the ACL, partial or complete).
1. Eminentia fracture:
Non-displaced fractures of the attachment of the ACL to the tibia are treated with a 6-week stretched thigh castor tube. An X-ray or CT scan after the plaster has been applied can best show the extent of displacement. If the fracture is not correct, it will need to be fixed with surgery. Darna also follows a 6-week plaster immobilization. Improper tightening of this joint can lead to extension limitations and knee instability.
2. Ligamentary ACL injuries:
Partial ACL tears (< 50% ACL tear) can be treated conservatively with a 3-4 month physical therapy exercise program. Tears > 50% give poorer outcomes and more chance of complete ruptures in children.
The treatment of complete ligamentous ACL ruptures is controversial. There are two options: 1) Conservative treatment with physiotherapy, pivoting sports prohibition (pivot sports are sports with many rotational movements of the knee such as football, hockey, indoor sports) and possibly. brace. After growing out, an ACL reconstruction can take place in case of permanent instability; 2) ACL reconstruction in open growth plates.
Several case reports have been published describing spontaneous recovery from ligamentous ACL injury in children. However, unlike the posterior cruciate ligament and the side ligaments of the knee, a ruptured ACL usually does not heal. In recent years, the group of children with open growth plates has received more attention. The new guideline Anterior Cruciate Ligament Injury from the Dutch Orthopedic Association (NOV 2018) is the first to provide advice on these injuries in children. Despite increasing scientific interest over the past decade, there is still controversy about the best treatment of ACL injuries in children with open growth plates.
Treatment of ACL injuries in children with open growth plates
The treatment of children with ACL injuries and open growth plates requires good information about the advantages and disadvantages to the child, parents and sports coaches. The treatment goals are:
- Restore a stable, functioning knee for a healthy active lifestyle for the rest of his/her life
- Reducing the impact of existing or risk of further damage to meniscus and cartilage, osteoarthritis and the need for surgery
- Minimizing risk on growth disorders and deformities of the femur and tibia
Rehabilitation with adequate physiotherapy (possibly supplemented with a knee brace) can be a good option. This will take 3-4 months.
The downside of conservative treatment is the possible need for sport adaptation. Several authors have also reported that conservative treatment of an ACL tear in a child with open growth plates leads to more secondary meniscus and cartilage injuries when the children returned to sports.
In the latest IOC (International Olympic Committee) consensus, the following indications are stated for ACL surgery in children:
- Suture of an accompanying meniscal injury or cartilage fixation
- Persistent instability after adequate conservative treatment
- Unacceptable restrictions in (sports) activities to avoid “giving-way” ” to limit.
The new guideline for Anterior Cruciate Ligament Injury shows some evidence that the chance of returning to sport appears to be greater for children who have had surgery than for children who have been treated conservatively. More than 90% of children and adolescents return to sport after ACL surgery. However, it is also known that few children achieve the level of top sport after an ACL rupture (with or without surgery).
The downside of an ACL operation in children is a higher chance of a cruciate ligament rupture (new tear) compared to adults. It has been scientifically shown that children under the age of 18 are up to 8x more likely to have a new ACL tear. This high probability of reruption is confirmed in Scandinavian registers. In the age group of 13-15 years, 6.7% ACL revision surgeries were performed compared to 2% in adults. The combination of age (13-19 years) and playing football increases the risk of ACL revision surgery up to 3 times compared to adults. In a longer follow-up of 10-15 years, up to 30% reruptions are described after ACL reconstruction in children with open growth plates.
Maxima Medical Center uses a special surgical technique that causes as little damage as possible to the growth plates. Hamstring tendons are the graft of choice for ACL reconstruction in children with open growth plates. The downside of ACL reconstructions in the growing child is the risk of growth disturbances due to heat development when drilling tunnels. These percentages range from 2-24% depending on the accuracy of the measurements. Little is known about what happens to the new cruciate ligament when the child grows a lot.
In summary, there is no convincing evidence yet as to which surgical technique is best used in children with open growth plates. To date, there is also no scientific evidence that ACL reconstruction protects the knee against knee osteoarthritis in the longer term.
PROMS in children
Patient Reported Outcome Measures (PROMS) are important for measuring the effect of treatment. A study by Dietvorst et al. on psychometric properties has shown that the Pedi-IKDC is the best PROM in children aged 6-18 years. I also use this questionnaire with children with ACL injuries. In Dutch practice, there appears to be a large variation in both conservative and surgical treatment of children with open growth plates and ACL injuries. This is no different from the rest of Europe. There are still many unanswered questions about optimal care for this target group. It is important to follow the child for growth disorders after ACL reconstruction until the end of growth.
The controversy and increasing incidence of ACL injuries in children has led to scientific interest in newer surgical techniques of primary repair of ACL using scaffolds (Bridge-Enhanced ACL Repair (BEAR). Long-term results of these techniques are not yet known.
There is a need for long-term prospective studies on different treatment algorithms for children with ACL injuries. There are various initiatives for this. In the Netherlands, a registration system is currently being developed at the initiative of the Dutch Association for Arthroscopy. The research group of Coöperatie Orthopedie Groot Eindhoven has a research line for Pediatric VKB injuries and treatment. Martijn Dietvorst is one of the PhD students and, together with various MSc students, conducts outcome studies after pediatric cruciate ligament surgery. Máxima Medical Center works together with Aarhus University in Denmark, where a national VKB registration system already exists.
Máxima Medical Center, as a center of expertise for cruciate ligament injuries in adults and children, is also a partner in ESSKA’s European Pediatric Acl Monitoring Initiative (PAMI). At the ESSKA conference in Glasgow (8-12 May 2018, Scotland), Dr RPA Janssen chaired the Instructional Course Lecture Pediatric injuries: treatment and challenges. Together with European and American experts in this field, the latest update of knowledge and future research questions about ACL injuries and treatment in children are provided.
In summary, an ACL rupture is a dramatic trauma for the active child with open growth plates. There are often more questions than answers. Experience shows that an open discussion about the current state of affairs, uncertainties, controversies and relative scientific knowledge on the subject usually leads to a wise decision with the active involvement of child and parents.
For scientific references on ACL injuries and treatment in children, I refer to Publications.