Session VII - Tibia
Distal Fourth Tibia-Fibula Fractures Treated with Intramedullary Nails: Factors Affecting Alignment
Russell D. Weisz, MD; Nirmal C. Tejwani, MD; Kenneth J. Koval, MD; Roy W. Sanders, MD; Tampa General Hospital, Florida Orthopaedics, Tampa, Florida, USA
Purpose: With the development of extremely distal locking, the application of intramedullary (IM) nails has extended to the treatment of distal metaphyseal tibia fractures. Unfortunately, this has been associated with a reported increase in malalignment. The goal of this retrospective review was to determine the associated risk factors with postoperative malalignment and to determine if anything could be done to improve this outcome.
Methods: Seventy-two distal-fourth tibia fractures (71 patients), all associated with a same level fibula fracture were identified using the trauma registry at two level one trauma centers. Two cases had segmental tibia fractures, while five other cases presented with a segmental fibula fracture, one of which had a syndesmotic disruption in the distal fourth component. Fifty-four patients were men (one bilateral fracture) and seventeen were women. The ages ranged from 15-97 years (average, forty-one years). Fractures were classified using the AO/OTA (43.A.1-37, 43.A.2-24, 43.A.3-11), and Gustilo and Anderson systems (43 closed, 7 type I, 4 Type II, 11 Type IIIA, 7 type IIIB). All tibia fractures were treated with a statically locked intramedullary nail, reamed insertion was at surgeon discretion. The distal fibula fracture was treated with plate fixation in 21 cases, based on the surgeon's discretion regarding tibial instability and mortise involvement at the time of nailing. Distance of the fracture from the plafond and from the most proximal of the distal locking screws, as well as the number and orientation of the distal locking screws were recorded. Other variables that were collected included: nail diameter, gender, age, method of injury, additional surgical procedures, and complications. Radiographic malalignment was defined as more than 5 degrees of varus/valgus angulation, or more than 10 degrees of anterior/posterior angulation. Associations of independent variables with malalignment were evaluated using the chi-square test, Fisher's exact test, two-sample t-test, or the Wilcoxon two-sample test. Clinical and radiographic follow-up was assessed in the post-operative period (defined as "immediate"), and at the time of expected union (minimum 12 weeks post surgery, defined as "late").
Results: "Immediate' group. Nine of seventy-two fractures (13%) were identified as being malaligned postoperatively. Variables associated with post-operative malalignment included: method of injury defined as pedestrian struck, (P < 0.05, Fisher's Exact test), Gustilo fracture classification type III (P < 0.05, Fisher's Exact test), severity of AO/OTA classification (P < 0.05, Wilcoxon two-sample test), and younger age (P < 0.0001, two sample t-test). Although eight out of nine malaligned fractures had no supplemental fibula fixation, this was not statistically significant (P = 0.1571 Fisher's Exact test).
"Late" malalignment was evaluated in the remaining 63 fractures. Fractures that were eliminated from this analysis included: one fracture in one patient who expired one week postoperatively and three fractures in three patients lost to follow-up. Follow-up averaged 25 weeks (range=1254 weeks). Of the remaining 59 fractures, 19 had supplemental fibula fixation. Six tibiae (10%) were malaligned, none of which had fibula fixation. While this variable was not significant, there was a statistical trend (P = 0.0852 Fisher's Exact test). Distal locking screw configuration for these six cases revealed that 5/6 had only one A-P and one M-L screw. No fracture with more than one M-L screw shifted. Distal locking screw configuration was the only variable that was statistically significant for malaligment in the "late" group (P < 0.05, Fisher's Exact test).
When combining the "immediate" and "late" groups, 14/15 malaligned fractures had no fibula fixation. This was shown to be statistically significant (p<0.05, Fisher's exact test). There was no change with the other variables when combining the two groups.
Conclusions: Intramedullary nailing of distal metaphyseal tibia fractures, specifically those associated with same level fibula fractures, have been linked with malalignment. These fractures are unique because the nail does not obtain a cortical interference fit with the distal tibial fragment, and adequate reduction depends upon precise center-center placement of the nail. Furthermore, pivoting can occur around the axis of the A-P screw when only one M-L locking screw is placed. Finally, if only the tibia is stabilized, then tibial alignment is solely dependent upon the distal locking screws. This becomes critical when bony contact of the tibia is minimal. Our data indicates that higher energy injuries in younger patients predispose the leg to immediate postoperative malalignment. In conclusion, it appears that plate fixation of the fibula just prior to intramedullary nailing of the tibia assists in obtaining and maintaining tibial reduction. In addition, we recommend placement of at least two M-L distal locking screws when nailing distal metaphyseal tibia fractures.