Objective The purpose of this study was to determine whether damage to the physis, articular cartilage, medial collateral ligament (MCL) and medial patellofemoral ligament (MPFL) can be avoided during femoral tunnel drilling in an anatomic, all-epiphyseal double-bundle (DB) reconstruction of the posterior cruciate ligament (PCL) in the skeletally immature knee using three-dimensional (3D) reconstruction modelling.
Methods CT scans of eight male skeletally immature cadaveric knee specimens between the ages 5 and 11 years were used to create eight 3D models of paediatric femurs. Using these 3D models, 5 mm, 6 mm and 7 mm tunnels were placed in the anatomic footprints of the anterolateral (AL) and posteromedial (PM) bundles, simulating an outside-in technique. Both full-length and a predetermined socket length were simulated in various trajectories to achieve the following goals: (1) avoid the femoral physis and periphyseal ring; (2) create adequate spacing (≥2 mm) between the tunnels to avoid significant tunnel convergence in the PCL footprint; (3) avoid articular cartilage of trochlea and medial condyle; and (4) avoid the femoral origin of the MCL and MPFL.
Results In all eight models, both tunnels could be placed in the PCL origin without damaging the physis, articular cartilage, MCL or MPFL. There was an adequate bone bridge (≥2 mm) between the two tunnels in ages 7–11 with a 6–7 mm AL tunnel and a 5–6 mm PM tunnel, as well as the 5-year-old model, using a 6 mm and 5 mm AL and PM tunnel, respectively.
Conclusion This computer-aided design model demonstrated that 5 mm, 6 mm and 7 mm all-epiphyseal tunnels can be placed within the footprint of the PCL while avoiding direct injury to the femoral physis, articular cartilage, MCL and MPFL. By understanding the location and trajectory of tunnel and socket placement, DB PCL reconstruction may be performed in skeletally immature knees without causing damage to the distal femoral physis and surface ligament footprints.
Level of evidence IV.
- repair / reconstruction
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Contributors All authors: study design, data collection and manuscript preparation.
Competing interests KGS, PDF, AFA, and TJG are members of the ROCK (Research in OsteoChondritis of the Knee) study group which receives unrestricted educational grants from Vericel and AlloSource. AFA holds a patent and receives royalties from OrthoPediatrics for an ACL reconstruction device, acts as a consultant for DePuy Mitek, Ceterix, Flexion Therapeutics, Orthopediatrics and Cotera and received payment for educational presentations from OSET and ETO.
Ethics approval Our institutional review board was consulted prior to the initiation of this study. As this study included access to cadaveric specimens without any patient identifiers or contact with the family, IRB approval was not deemed necessary. The specimens were provided by an allograft harvesting facility, which had received family consent for use of tissue for research purposes (AlloSource, Centennial, Colorado, USA).
Provenance and peer review Not commissioned; externally peer reviewed.
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