Influence of medial parapatellar nail insertion on alignment in proximal tibia fractures--special consideration of the fracture level.

INTRODUCTION: Although a lateral starting point for tibial nailing is recommended to avoid valgus misalignment, higher rates of intra-articular damage were described compared with a medial parapatellar approach. The aim of this anatomic study was to evaluate the fracture level allowing for a safe medial nail entry point without misalignment or dislocation of fragments. MATERIALS AND METHODS: Thirty-two fresh-frozen cadaver lower extremities were used to create 1-cm osteotomies at four different levels (n = 8) from 2 cm to 8 cm below the tibial tuberosity. Nine-millimeter unreamed solid titanium tibial nails (Connex, I.T.S. Spectromed, Lassnitzhohe, Austria) were inserted from a medial parapatellar incision. Misalignment (degree) and dislocation of the distal fragment were measured in the frontal and sagittal plane. RESULTS: A medial parapatellar approach for tibial nail insertion mainly caused valgus and anterior bow misalignment and ventral and medial fragment displacement. Mean misalignment and fragment displacement did not exceed 0.5 degree if the osteotomy was performed 8 cm to 9 cm below the tibial tuberosity. DISCUSSION: According to the results of this study, a medial parapatellar approach can be performed without misalignment and fragment dislocation in proximal tibia fractures extending 8 cm or more below the tibial tuberosity.

Intramedullary nailing of proximal tibia fractures--an anatomical study comparing three lateral starting points for nail insertion.

INTRODUCTION: Intramedullary nailing is challenging in proximal tibia fractures, associated with high rates of malalignment. To date, no studies report the potential of lateral tibia nail insertion to correct primary valgus malalignment, commonly seen in proximal quarter fractures. MATERIALS AND METHODS: 18 fresh-frozen cadaver lower extremities were used to simulate an AO/OTA 41-A3 fracture. Six nails (Expert Tibial Nailing System, Synthes, Salzburg, Austria) were inserted at the lateral third, six nails at the middle third and six nails at the medial third of the lateral tibia plateau. After nail insertion, alignment in the coronal plane was recorded. RESULTS: Mean varus malalignment was dependent on the entry point at the lateral tibia plateau. Mean varus malalignment was 16 degrees if nails were inserted at the lateral third, 10 degrees at the middle third and 4 degrees after nail insertion at the medial third. If nails were inserted from the medial third, valgus malalignment was recorded in two specimens. DISCUSSION: The effect of correction of coronal malalignment in proximal tibia fractures is dependent on the point of nail entry at the lateral plateau. Primary valgus deformation up to 20 degrees can be corrected by inserting tibia nails at the lateral third of the lateral tibia plateau. Surgeons should be aware of possible varus deformity and valgus malalignment despite lateral nail insertion.