Comparison between suprapatellar and parapatellar approaches for intramedullary nailing of the tibia. Cadaveric study

Intramedullary nailing is one viable option for treating fractures of the tibia with a short, proximal segment. For a procedure being carried out with the knee in a semi-extended position, either a suprapatellar or parapatellar approach may be used. The objective of this study is to demonstrate whether the entry point for tibia nails is obtainable through suprapatellar or parapatellar approaches and to evaluate the most frequent injuries of the knee with these two approaches.

Paired legs from 10 fresh frozen cadavers were used. An arthroscopy was performed in each knee, documenting the status of the knee prior to the insertion of the tibia nail. In a random manner, the left or right leg underwent nailing with a suprapatellar or parapatellar approach in a semi-extended position. Fluoroscopy was utilized in each case to localize the entry point, and a tibia nail was inserted in all cases. A knee arthrotomy was then performed and the status of the following structures was assessed: patella and trochlea cartilage, tibia plateau cartilage, inter-meniscal ligament, lateral and medial meniscus, and the ACL.

The correct fluoroscopy entry point was achieved in all of the specimens (20). Three legs (3/10) with parapatellar approach had intra-articular disruption. In legs with a suprapatellar approach, patellar cartilage and trochlea cartilage damage was found in two of the specimens, respectively. There was one specimen with cartilage damage in the parapatellar approach. There were no meniscal injuries. Partial laceration of the intermeniscal ligament was found in three of the knees for each approach. One ACL injury was found in the suprapatellar group. Mean distance from the entry point to major structures is not significantly different with either approach. (p=0.45).

A good fluoroscopic entry point can be achieved using either the parapatellar or suprapatellar approach. The parapatellar approach for tibia nailing has similar rate of soft tissue damage compared to the suprapatellar approach. The suprapatellar approach damaged the cartilage in one-third of the cases and if cartilage injury occurs with the parapatellar approach, this is located in a low risk area.