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Athymic Rat Model for Evaluation of Engineered Anterior Cruciate Ligament Grafts
Published on: March 26, 2015
Effects of a tensioned tendon graft in a bone tunnel across the rabbit physis
1Division of Orthopaedics, Children's Hospital of Eastern Ontario, University of Ottawa, Canada.
Insights
Drilling across the growth plate during anterior cruciate ligament reconstruction in immature rabbits caused significant growth arrest. Larger drill holes resulted in more severe deformities, advising against tunnels impacting over 1% of the physis area.
Area of Science:
- Orthopedic Surgery
- Pediatric Orthopedics
- Skeletal Biology
Background:
- Anterior cruciate ligament (ACL) disruption in children raises concerns about surgical reconstruction impacting growth.
- Standard ACL reconstruction techniques involve drilling tunnels across the physis, potentially causing growth plate arrest.
Purpose of the Study:
- To evaluate the risk of growth plate arrest from drilling across the proximal tibial and distal femoral physes in immature rabbits.
- To assess if tendon grafts protect against physeal arrest after ACL reconstruction.
Main Methods:
- Tunnels of varying diameters (1.95-3.97 mm) were created across the proximal tibial and distal femoral physes in immature rabbits.
- Patellar tendon autografts were used for ACL reconstruction in some animals.
- Radiographic and histological examinations were performed after 4 months.
Main Results:
- Eight out of eleven rabbits experienced growth arrest in one or both physes.
- A direct correlation was observed between larger drill hole diameter and increased deformity.
- The proximal tibial physis was most susceptible to growth arrest.
- Graft insertion did not prevent physeal arrest.
Conclusions:
- Drilling across the tibial and femoral physes for ACL reconstruction in skeletally immature patients carries a high risk of growth arrest.
- Tunnels occupying 1% or more of the physis area should be avoided in pediatric ACL reconstruction.
- This study advises against current ACL reconstruction tunnel placement in very young patients due to growth disturbance risks.
Abstract:
Children who sustain anterior cruciate disruption often are denied the standard reconstructive procedures because of the concern that drilling across the physis of the tibia and femur and compression from a tensioned graft will result in growth plate arrest. To test this concept and to assess whether a tendon placed in the tunnel would function in a manner similar to a fat graft after the resection of a physeal bar, tunnels were made across the proximal tibial physis and distal femoral physis in a group of immature rabbits. Four tunnel diameters were used from 1.95 to 3.97 mm, in three rabbits at each diameter, with patellar tendon autografts being used as the reconstruction of the anterior cruciate ligament in two of the animals. The knees were radiographed every 4 weeks, and the animals were euthanized 4 months after surgery. The surgically treated and control knees were salvaged, and each knee was examined grossly, radiographically, and histologically. Eight of the 11 animals had growth arrest of one or both physes. The larger the drill hole diameter the more marked was the deformity. The proximal tibial physis seemed to be the most vulnerable for growth arrest, occurring in eight of the knees. The insertion of a tendon did not seem to offer any protection to physeal arrest. Because of these findings, it is not recommended that tunnels involving 1% or more of the area of the physis be placed across the tibial and femoral physis to reconstruct the anterior cruciate in very skeletally immature children.
