The "N+10 Rule" to Avoid Graft-Tunnel Mismatch in Bone-Patellar Tendon-Bone ACL Reconstruction Using Independent Femoral Tunnel Drilling.

Background: Graft-tunnel mismatch (GTM) is a common problem in anterior cruciate ligament (ACL) reconstruction (ACLR) using bone-patellar tendon-bone (BPTB) grafts. Hypothesis: Application of the "N+10 rule" in endoscopic ACLR with BPTB grafts will result in acceptable tibial tunnel length (TTL), minimizing GTM. Study Design: Controlled laboratory study. Methods: Endoscopic BPTB ACLR was conducted on the paired knees of 10 cadaveric specimens using 2 independent femoral tunnel drilling techniques-accessory anteromedial portal and flexible reamer. The graft bone blocks were trimmed to 10 × 20 mm, and the intertendinous distance (represented by "N") between the bone blocks was measured. The N+10 rule was used to set the angle of the ACL tibial tunnel guide to the appropriate number of degrees for drilling. The amount of excursion or recession of the tibial bone plug in relation to the anterior tibial cortical aperture was measured in both flexion and extension. A GTM threshold of ±7.5 mm was set based on prior studies. Results: The mean BPTB ACL intertendinous distance was 47.5 ± 5.5 mm. The mean measured intra-articular distance was 27.2 ± 3 mm. Using the N+10 rule, the mean total (flexion plus extension) GTM was 4.3 ± 3.2 mm (GTM in flexion, 4.9 ± 3.6 mm; GTM in extension, 3.8 ± 3.5 mm). In 18 of 20 (90%) cadaveric knees, the mean total GTM fell within the ±7.5-mm threshold. When comparing the actual measured TTL to the calculated TTL, there was a mean difference of 5.4 ± 3.9 mm. When comparing femoral tunnel drilling techniques, the total GTM for the accessory anteromedial portal technique was 2.1 ± 3.7 mm, while the total GTM for the flexible reamer technique was 3.6 ± 5.4 mm (P = .5). Conclusion: The N+10 rule resulted in an acceptable mean GTM in both flexion and extension. The mean difference between the measured versus calculated TTL using the N+10 rule was also acceptable. Clinical Relevance: The N+10 rule is a simple and effective intraoperative strategy for achieving desired TTL regardless of patient-specific factors to avoid excessive GTM in endoscopic BPTB ACLR using independent femoral tunnel drilling.

Lateral Extra-Articular Tenodesis Staple Risks Penetration of Anterior Cruciate Ligament Reconstruction Tunnel.

Purpose: To identify the risk of anterior cruciate ligament (ACL) femoral tunnel penetration with the use of a staple for lateral extra-articular tenodesis (LET) graft fixation and to determine whether this varied between 2 different techniques for ACL femoral tunnel drilling. Methods: Twenty paired, fresh-frozen, cadaver knees underwent ACL reconstruction with a LET. Left and right knees were randomized to ACL reconstruction with femoral tunnel creation by use of either a rigid guide pin and reamer through the accessory anteromedial portal or by the use of a flexible guide pin and reamer through the anteromedial portal. Immediately after tunnel creation, the LET was performed and fixated with a small Richard's staple. Fluoroscopy was used to obtain a lateral view of the knee to determine staple position, and visualization of the ACL femoral tunnel was performed with the arthroscope to investigate penetration of the staple into the femoral tunnel. The Fisher exact test was conducted to determine whether there was any difference in tunnel penetration between tunnel creation techniques. Results: The staple was noted to penetrate the ACL femoral tunnel in 8 of 20 (40%) extremities. When stratified by tunnel creation technique, the Richards staple violated 5 of 10 (50%) of the tunnels made via the rigid reaming technique compared with 3 of 10 (30%) of those created with a flexible guide pin and reamer (P = .65). Conclusions: A high incidence of femoral tunnel violation is seen with lateral extra-articular tenodesis staple fixation. Level of Evidence: Level IV, controlled laboratory study. Clinical Relevance: The risk of penetrating the ACL femoral tunnel with a staple for LET graft fixation is not well understood. Yet, the integrity of the femoral tunnel is important for the success of ACL reconstruction. Surgeons can use the information in this study to consider adjustments to operative technique, sequence, or fixation devices used when performing ACL reconstruction with concomitant LET to avoid the potential for disruption of ACL graft fixation.

Diagnosing Fractures of the Distal Tibial Articular Surface in Tibia Shaft Fractures: Is Computed Tomography Always Necessary?

OBJECTIVES: To identify the incidence of distal articular fractures in a series of distal third tibia shaft fractures and to report the utility of both computed tomography (CT) scans and Radiographic Investigation of the Distal Extension of Fractures into the Articular Surface of the Tibia (RIDEFAST) ratios for identification of articular involvement. DESIGN: Retrospective cohort. SETTING: Level 1 trauma center. PATIENTS: Four hundred seventeen patients with distal third tibia shaft fractures were included in the study. INTERVENTION: Intramedullary nail or plate fixation. MAIN OUTCOME MEASURES: Type of articular fracture, time of diagnosis, and RIDEFAST ratios. RESULTS: One hundred one of the 417 distal third fractures (24%) had a fracture of the distal tibia articular surface. Of these 101 fractures, 41 (41%) represented an extension of the primary fracture line and 60 (59%) were separate malleolar fractures. Of the 101 articular fractures, 95 (94%) were identified preoperatively and 6 (6%) were identified intraoperatively. Of the 95 fractures identified preoperatively, 87 (92%) were identified on plain radiographs and 8 (8%) by CT scan. Thirty-five preoperative CT scans were performed on distal third tibia shaft fractures in search of an intra-articular fracture. In 27 patients (77%), no articular fracture was present, representing an overall yield of 23% among CT scans performed to rule out an articular fracture in distal third tibia shaft fractures. RIDEFAST ratios for all 101 distal tibia shaft fractures with articular involvement and 100 fractures with no articular involvement were not significantly different (P > 0.05) using both coronal and sagittal plane measurements. CONCLUSIONS: CT scans performed on distal third tibia shaft fractures in search of articular fractures had a low yield (23%). Widespread use of CT scan to diagnose fractures of the distal tibia articular surface in the setting of distal tibia shaft fractures does not seem warranted. No statistically significant differences in RIDEFAST ratios were found between fractures with and without articular involvement, indicating that more work is necessary before RIDEFAST can be used to reliably rule out articular involvement in this setting. LEVEL OF EVIDENCE: Diagnostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Clinical and radiographic outcomes following retrograde SIGN fin nailing for femoral shaft fractures.

PURPOSE: The Surgical Implant Generation Network (SIGN) intramedullary nail was designed for use in resource limited settings which often lack fluoroscopy, specialized fracture tables, and power reaming. A newer design iteration, the SIGN Fin nail, was developed to further simplify retrograde femoral nailing by making proximal interlocking screw placement unnecessary. Instead, the leading end of the Fin nail achieves stability through an interference fit within the proximal femoral canal. While the performance of the traditional SIGN nail has been reported previously, no large series has examined long-term clinical and radiographic outcomes of femoral shaft fractures treated with the SIGN Fin nail. METHODS: The SIGN online surgical database was used to identify all adult femoral shaft fractures treated with the SIGN Fin nail since its introduction. All patients with minimum 6 month clinical and radiographic follow-up were included in the analysis. Available demographic, injury, and surgical characteristics were recorded. Fracture alignment was evaluated on final follow-up radiographs using a previously validated on-screen protractor tool. Coronal and sagittal plane alignment measurements were recorded as deviation from anatomic alignment (DFAA), with units in degrees. Fracture healing was assessed on final follow-up radiographs, with union defined as any bridging callus and/or cortical remodeling across one cortex on orthogonal views. Clinical outcomes available in the database included knee range of motion (ROM) greater than 90° and weight-bearing status at final follow-up. Clinical and radiographic outcomes were then compared between patients with united and nonunited fractures. RESULTS: The database query identified 249 femoral shaft fractures stabilized with the Fin nail in 242 patients who had minimum 6 month clinical and radiographic follow-up. Final follow-up radiographs were performed at an average of 48 weeks postoperatively. Average coronal and sagittal plane alignment measured on final follow-up radiographs were 2.18° and 2.58°, respectively. The rate of malalignment (DFAA > 10° in either plane) at final follow-up was 6%. Two hundred twenty-nine fractures (92%) were united at final follow-up. Overall, 209 (84%) of patients achieved full weight bearing and 214 (86%) achieved knee ROM >90° at final follow-up. Compared to patients with united fractures, those with nonunion were less likely to achieve full weight bearing (20% vs 90%, P < .001) and knee ROM >90° (30% vs 91%, P < .001). There was no significant difference in mean DFAA between united and nonunited fractures in the coronal (2.1° vs 3.8°, P = .298) or sagittal (2.5° vs 3.5°, P = .528) planes. CONCLUSION: The SIGN Fin nail achieves satisfactory radiographic alignment and clinical outcomes at minimum 6 month follow-up. The overall union rate is comparable to that achieved with the standard SIGN nail. Ease of implantation makes the Fin nail an attractive option in resource-limited settings.