FACTORS ASSOCIATED WITH THE DEVELOPMENT OF SYMPTOMATIC INTERLOCKING SCREWS WITH INTRAMEDULLARY NAIL STABILIZATION OF TIBIA FRACTURES

Treatment of tibia fractures with intramedullary nail stabilization is a commonly performed orthopedic procedure. The incidence of complications after undergoing intramedullary nail stabilization of tibia fractures is relatively low, however, a small percentage of patients develop symptomatic pain at the site of their interlocking screws, necessitating removal. The primary goal of our project was to identify reasons for removal of interlocking screws, and secondary goal to assess factors associated with the development of symptomatic interlocking screws to better identify those at risk and reduce the occurrence of this complication. This would be beneficial in reducing the need for repeat surgery to remove symptomatic interlocking screws. Purpose (a): The primary purpose of this study is to identify reasons for removal of interlocking screws after treatment of tibial shaft fractures with intramedullary nail stabilization. The secondary goal is to assess factors associated with development of symptomatic interlocking screws. Methods (b): A retrospective chart review was performed to identify a consecutive series of patients who underwent stabilization of a tibial shaft fracture with intramedullary nail from July 1st, 2005 to July 1st, 2011. We then identified those who underwent removal of interlocking screws at a later date (Group 1). These patients were then compared with a control-matched group (Group 2) who did not require removal of interlocking screws. Patients with pain identified at the interlocking screw sites either proximally or distally were considered to be symptomatic. Patients’ charts were reviewed to obtain demographic, radiographic, and clinical data. Statistical analysis was then performed comparing certain factors between the two groups. Results (c): 20 patients (Group 1) were identified who underwent removal of interlocking screws, 16 (80%) for symptomatic screws and 4 (20%) for dynamization due to non-union. 30 patients (Group 2) were identified who did not require screw removal. Of the patients undergoing screw removal for symptomatic screws, 15 (93%) had complete resolution of symptoms after screw removal. All patients undergoing screw removal for dynamization/non-union purposes went on to fracture union. Group 1 had a higher percentage of males vs. females compared to group 2 (p = 0.019). Average time to fracture union for Group 1 was 32.7 weeks vs. 15.5 weeks for Group 2 (p = 0.014). 14/20 (70%) patients were smokers in Group 1 vs. 13/30 (43%) in Group 2 (p = 0.003). Average Injury Severity Scores (ISS) and Mangled Extremity Scores (MES) for Group 1 were 16.1 and 3.3 respectively, and 6.6 and 3.2 respectively for Group 2 (p = 0.007/0.66). Group 1 had a higher percentage of open fractures (60%) vs. Group 2 (20%). Group 1 had a higher percentage of shaft fractures (40%) vs. Group 2 (27%) (p = 0.007). Group 1 had a higher likelihood and number of associated injuries vs. Group 2 (0.025). The groups did not differ significantly with respect to age, BMI, mechanism of injury, time to surgery, or associated fibula fracture. Conclusions (d): The most common reason for removal of tibial intramedullary nail interlocking screws was not for dynamization, but for pain. Removal of interlocking screws resulted in resolution of pain in 93% of patients. Patients who develop symptomatic interlocking screws were more likely to be male,have delayed fracture union, smoke, have higher ISS scores, open fractures, and higher number of associated injuries. By identifying those that are at higher risk for development of symptomatic interlocking screws after intramedullary nail stabilization of tibia fractures (smokers, males, open shaft fractures, delayed union, higher ISS scores, and presence/greater number of associated injuries) we may have a better ability to counsel patient's about their expected outcome and possible development of complications.