Suprapatellar Nail Insertion for Tibial Shaft Fractures: Better Radiographic Results, But Are They Clinically Relevant?

Commentary Makaram et al. compare radiographic, clinical, and patient-reported outcomes (PROs) after nailing of 219 consecutive tibial shaft fractures at a level-I trauma center in England using either the newer suprapatellar (SP) or the traditional infrapatellar (IP) insertion technique. The authors have no apparent bias and utilized what appear to be unbiased and appropriate outcome measures, including critical, objective, and reliable assessment of the radiographic entry point (nail insertion-point accuracy, NIPA), alignment, and (in approximately one-half of the patients) 1 to 3-year clinical outcomes (validated PROs including the Lysholm Knee Score [LKS], Oxford Knee Score [OKS], and an analogue scale for satisfaction). Only 8 patients were lost to follow-up (4 due to death). The authors concluded that SP nailing yielded superior radiographic findings (NIPA and malreduction rate, their 2 primary outcome measures) but no difference in the rate of malunion or in any of the PROs (their secondary outcome measures). The implication is that SP may be the "better" of the 2 approaches. I believe that their methodology and results are accurate, but I would draw slightly different conclusions. The primary message of this study, in my opinion, is that the new SP and the old IP approach for nailing tibial shaft fractures give equivalent and very good results. There are slight radiographic advantages to the SP approach, but probably not clinically important ones. Based on the premise that there is an identified "ideal" starting point, the authors were able to objectively and accurately measure the actual entry point (with excellent reliability) and then identify the distance between the 2 points (NIPA). However, the significant improvement in NIPA was only 2 mm (5 versus 7 mm) and probably not clinically important. The malreduction rate was 3% with the SP approach versus 11% with the IP approach, a difference that would appear to be not merely statistically significant but clinically important. However, several of the postoperative malreductions did not result in malunions at healing; there was no difference in the eventual malunion rate. Some of the malreductions apparently healed with improved alignment, and some of the early "malunions" were well reduced on postoperative radiographs. The authors emphasized the higher rate of malreduction with the IP approach, whereas I would also note that finding but emphasize that (1) there was no difference in the ultimate malunion rate, (2) postoperative malreduction does not always cause malunion, and (3) conversely, malunion can occur despite good postoperative alignment, especially in patients older than 60 years. Therefore, the statistically significant difference in malreduction may not be clinically important. The patients in this series were treated at the discretion of the surgeons, including the choice of surgical approach (IP versus SP) as well as what constitutes an "acceptable" reduction. Retrospectively, the authors identified 20 patients with "malreduction" (≥5°). It was not clear if the treating surgeons identified and accepted this angulation or missed it. Occasionally the surgeons did use supplementary techniques (clamps or unicortical plates, but not blocking screws) to obtain reduction. However, it is not clear what the surgeons considered an "acceptable" reduction, meaning one that did not require an intraoperative change. Another conclusion that I draw from these results is that there may be a tendency for more malreductions (fewer "auto-reductions") after the IP than the SP approach and surgeons using the IP approach may need to be more vigilant about avoiding malreductions and resort to more supplemental techniques (clamps, unicortical plates, blocking screws) to obtain and maintain acceptable reduction. SP nailing supposedly improves reduction and is technically easier, but it also supposedly reduces postoperative anterior knee pain1. The authors did not directly measure anterior knee pain, but it is a component of all 3 PROs, and the pain component of the LKS did not differ between the 2 groups. If there was a difference in knee pain between the 2 approaches, it did not result in a difference in these PROs at 1 to 3 years postoperatively. SP nailing is sometimes promoted specifically for more proximal fractures, for which postoperative malalignment after nailing is even more common2. Makaram et al. specifically excluded extreme nailing (of fractures of the proximal or distal tibia), so we do not know if there are advantages to SP nailing in more proximal tibial fractures. There were no patients with fractures centered in the proximal metaphysis or with proximal extension into the knee joint3. Even among the diaphyseal fractures studied by Makaram et al., only 7% were in the proximal one-third of the diaphysis (OTA 42 subgroup 1)4. Their study did not specifically address 2 similar situations in which SP nailing might be superior to IP nailing: proximal tibial metaphyseal fractures (OTA 41A) and fractures involving the proximal third of the tibial shaft (OTA 42 group 1). Additional study of these fracture patterns might show greater benefit of SP nailing, as malreduction (apex anteromedial) has been reported with IP nailing5,6. Nevertheless, the authors have added a good deal of important data in trying to address the issue of the ideal starting point for tibial nailing.