Anterior Cruciate Ligament Reconstruction in the Skeletally Immature

Abstract

Introduction Anatomic anterior cruciate ligament (ACL) reconstruction has proven to be a reliable method to restore knee stability. However, the risk of physeal arrest with transphyseal tunnel placement in skeletally immature patients has raised concern regarding this technique. Conservative nonoperative management also has its limitations resulting in meniscal and chondral damage that may lead to degenerative joint disease and poor return to sport. Researchers have used animal models to study the threshold of physeal damage producing growth deformity. The purpose of this study was to examine the distal femoral and proximal tibial physes and determine the damage produced by drilling transphyseal tunnels. In addition, we attempted to find a reproducible angle at which to drill the tibial tunnel for safe interference screw placement. To do this, we used a custom software module. Methods A custom software package designed by our team was used: Module for Adolescent ACL Reconstructive Surgery (MAARS). This module created a 3-dimensional model of the distal femur and proximal tibia. The data required for MAARS were sagittal and coronal T1 magnetic resonance imagings of at least 1.5T. Thirty-one knee magnetic resonance imaging studies from patients aged 10 to 15 years old were used. The physes were segmented out to obtain volumetric measurements. Transphyseal tunnels were simulated based on the anatomic trajectory of the native ACL. The module calculated volume of physis was removed with the use of an 8-mm tunnel and the optimum angle for trajectory. Results Average volume of the tibial and femoral physis was 12,683.1 μL and 14,708.3 μL, respectively. The volume increased linearly with age. Average volume removed from the tibial and femoral physis was 318.4 μL and 306.29 μL, respectively. This represented 2.4% of the distal femoral physis and 2.5% of the proximal tibial physis. The volume percent removed decreased linearly with age. Manipulation of the variables demonstrates graft radius is the most critical parameter affecting the volume of physeal injury. Variation of graft diameter from 6 mm to 11 mm will increase volume percent removed from 2.3% to 7.8%, which averages 1.1% for every 1 mm increase. Increasing tunnel drill angle from 45 degrees to 70 degrees will decrease volume percent removed from 4.1% to 3.1% which averages 0.2% removed for each 5 degrees increase in drill angle. The average angle to maintain a distance of 20 mm from the proximal tibial physis was 65 degrees with a range of 40 degrees to 85 degrees. Discussion Less than 3% injury occurs when drilling an 8-mm tunnel across the physis. A vertical tunnel has minimal effect, but the tunnel diameter is critical. Interference screws can be placed safely to avoid the physis but requires careful planning. The MAARS module may be helpful in preoperative planning. Level of Evidence Diagnostic, level IV.

All-epiphyseal Anterior Cruciate Ligament Reconstruction in Skeletally Immature Patients

“…In terms of the tibial tunnel, although the techniques of Guzzanti et al [18] and Anderson [2,3] are more anatomic than the techniques of Micheli et al [30] and Kocher et al [23,24], they are more technically demanding and have a lower margin of error [2,3,18,22,23,30]. The obliquity of the tibial tunnel makes the intraarticular opening oblong and can accentuate any misplacement of the tunnel.…”

“…fixation or bony graft material across the physis or involve damage to the perichondral ring [24][25][26]. Based on animal models [12,36,39] and these clinical examples, the following general principles now are accepted [23,24]: fixation should not cross the physis, drill holes across the physis should be centrally located and as small as possible, and tensioning a soft tissue graft across a physis should be avoided if a large amount of growth remains.…”

Biomechanical Evaluation of Pediatric Anterior Cruciate Ligament Reconstruction Techniques

“…This can be attributed to an increase in the number of children and adolescents participating in competitive sports, a better recognition of the injury, and a better understanding of the importance of reconstruction in the acute setting. [15][16][17] Additionally, persistent instability has reportedly led to continued meniscal damage, chondral damage, and decreased activity levels, thereby suggesting that these injuries should be addressed acutely rather than delayed until skeletal maturity. 1,10,26,27,29 Despite the growing number of ACL reconstructions being performed in the pediatric population, there is no consensus on the optimal surgical technique.…”

Distal Femoral Physeal Implications of an Anatomic ACL Reconstruction in a Skeletally Immature Soccer Player

“…This is often referred to as the ''threshold of physeal injury,'' and is thought to be approximately 6% to 7% of the total area of the physis 1,4-6 . Additional precautions include avoiding any form of graft fixation that crosses the physis, using soft-tissue grafts when possible, and limiting the tensioning of grafts that cross the physis 1,4,7 . In addition, any transphyseal tunnel should be located centrally, with a small diameter, to minimize the volumetric injury to the physis 1,4,7 .…”

“…A nonoperative treatment approach places the meniscus and articular cartilage at risk for future injury because of the ongoing knee instability 2,3 . Consequently, a variety of techniques have been developed to reconstruct the ACL in patients with open physes, thereby restoring joint stability and reducing the risk of iatrogenic growth disturbance [1][2][3][4][5][6][7][8][9][10][11][12][13] .…”