Overview
Definition:
Pediatric Anterior Cruciate Ligament (ACL) reconstruction is a surgical procedure to restore the function of a torn ACL in children and adolescents, utilizing various graft materials to replace the damaged ligament.
Epidemiology:
ACL injuries are increasingly diagnosed in the pediatric population, often associated with sports participation
Prevalence varies, but estimates suggest it is rising
Boys are more commonly affected than girls
The choice of graft is crucial due to the presence of physes (growth plates) in this age group.
Clinical Significance:
Successful ACL reconstruction in children and adolescents is vital to restore knee stability, prevent further meniscal and chondral damage, and allow return to pre-injury activity levels
Inappropriate graft selection can lead to complications such as growth disturbance or graft failure.
Indications And Contraindications
Indications:
Indications for pediatric ACL reconstruction include complete ACL tears with associated knee instability, particularly in active children and adolescents involved in sports or with significant functional limitations
Associated injuries such as meniscal tears or collateral ligament injuries also strengthen the indication.
Contraindications:
Absolute contraindications are rare but may include active infection, significant comorbidities that preclude surgery, or very young children with open physes and minimal instability where conservative management might be sufficient initially
Relative contraindications include the desire to return to non-contact sports only, or significant knee stiffness precluding successful rehabilitation.
Graft Choices And Considerations
Autograft Options:
Autografts are harvested from the patient's own body
Common options include: Patellar tendon graft (bone-tendon-bone), Hamstring tendon graft (semitendinosus and gracilis tendons), Quadriceps tendon graft (with or without a bone block)
Each has advantages and disadvantages regarding strength, morbidity, and fixation.
Allograft Options:
Allografts are sourced from deceased donors
Commonly used are patellar tendon, Achilles tendon, and hamstring tendons
Advantages include no donor site morbidity and potentially faster surgery
However, concerns include disease transmission (rare with modern screening), slower incorporation, and potential for higher re-rupture rates in younger, more active individuals.
Physes Considerations:
A critical consideration in pediatric ACL reconstruction is the open physis
Tunnel placement must be carefully planned to avoid crossing the physes extensively to minimize the risk of growth arrest and angular deformities
Physeal-sparing techniques are often employed, particularly in younger children with significantly open physes.
Factors Influencing Choice:
Factors influencing graft choice include the patient's age and skeletal maturity, the specific demands of their sport, surgeon preference and experience, the presence of associated injuries, and potential for donor site morbidity
Bone-tendon-bone grafts offer strong fixation but have higher anterior knee pain rates
Soft tissue grafts (hamstring, quadriceps) can be less painful anteriorly but may have weaker initial fixation.
Surgical Technique Considerations
Tunnel Placement:
Accurate tunnel placement is paramount
Anatomic reconstruction aims to place tunnels in the precise native ACL insertion sites
For pediatric patients, careful consideration of physeal proximity is essential
Intra-articular tunnels are standard, while extra-articular or physeal-sparing tunnels may be used in younger children.
Fixation Methods:
Fixation methods vary depending on the graft type
Bone-tendon-bone grafts can be secured with screws or staples
Soft tissue grafts are typically fixed with interference screws, cortical buttons, or suture anchors
Biocompatible and absorbable fixation devices are often preferred in pediatric cases.
Reconstruction Techniques:
Double-bundle versus single-bundle reconstruction is debated, with double-bundle aiming to replicate the native ACL anatomy more closely, potentially offering better rotational control
In pediatric patients, the decision depends on the surgeon's expertise and the patient's specific injury pattern and anatomy.
Postoperative Management And Rehabilitation
Immediate Postoperative Care:
Postoperative care includes pain management, wound care, and knee immobilization (e.g., brace) as needed
Early range of motion exercises are crucial to prevent stiffness.
Rehabilitation Protocol:
A structured, progressive rehabilitation program is essential
This typically involves phases focusing on: reducing swelling and pain, restoring full range of motion, strengthening quadriceps and hamstrings, proprioception and balance training, and sport-specific drills
The long-term nature of bone and graft healing requires patience and adherence to the protocol.
Return To Sport:
Return to sport is a gradual process, typically occurring 6-12 months post-surgery, contingent on achieving strength, stability, and functional milestones
This is a critical period for graft healing and preventing re-injury
Gradual progression and clear return-to-sport criteria are vital.
Complications And Outcomes
Graft Failure And Re Rupture:
Graft failure, or re-rupture, can occur due to inadequate healing, poor fixation, or premature return to high-risk activities
Re-rupture rates in pediatric patients can be higher compared to adults, emphasizing the importance of meticulous surgical technique and comprehensive rehabilitation.
Donor Site Morbidity:
Autograft harvest can lead to donor site morbidity
Patellar tendon grafts may cause anterior knee pain, stiffness, and infrapatellar numbness
Hamstring tendon harvest can result in weakness of knee flexion
Quadriceps tendon harvest can cause anterior knee pain and a palpable defect.
Growth Plate Related Complications:
Complications related to the physes, such as growth arrest, premature physeal closure, or angular deformities (e.g., genu recurvatum or valgus/varus deformity), are a significant concern in pediatric ACL reconstruction
Careful tunnel placement is key to minimizing these risks.
Long Term Outcomes:
With appropriate graft selection and surgical technique, pediatric ACL reconstruction can lead to good functional outcomes, allowing young athletes to return to their desired activities
Long-term studies indicate that most children achieve satisfactory stability and function, though some may experience residual pain or stiffness.
Key Points
Exam Focus:
Physes management is paramount
Understand the advantages and disadvantages of autografts (patellar tendon, hamstring, quadriceps) versus allografts in pediatric ACL reconstruction
Be aware of donor site morbidity and potential growth plate complications.
Clinical Pearls:
Always consider skeletal maturity when choosing a graft and technique
Physeal-sparing techniques are crucial in younger patients
Close collaboration with the rehabilitation team is essential for optimal outcomes.
Common Mistakes:
Ignoring physeal proximity during tunnel drilling
Premature return to sport without adequate strength and stability
Underestimating the importance of a structured, long-term rehabilitation program
Inadequate assessment of psychological readiness for return to sport.