Session V - Femur
Pauwels' Type 3 Vertical Femoral Neck Fractures- What Is the Best Fixation Device?
Background: Controversy surrounds the ideal fixation device for the so-called "high shear angle" vertical femoral neck fracture. These fractures are thought to behave biomechanically in a fundamentally different way than more horizontal fractures. Some biomechanical studies have supported fixed angle devices for vertical fractures, but no clinical study exists to substantiate these recommendations. The purpose of this study is to retrospectively evaluate the outcomes of a larger consecutive series of purely Pauwels' type 3 transcervical femoral neck fractures to learn more about the outcomes, complications, and performance of various internal fixation devices.
Methods: Between January 1993 and March 2003, 55 Pauwels' 3 (OTA type 31B2.3) femoral neck fractures in 54 skeletally mature patients were treated with internal fixation at our level 1 trauma center. Radiographs were reviewed and fracture verticality was measured using the method of Pauwels. Only transcervical fractures with 70° of verticality or greater were included in the study. There were 37 males and 17 females with a mean age of 45 years. 14 patients were lost to follow-up; therefore, 41 fractures in 40 patients (37 displaced and 4 nondisplaced) were followed to union or revision surgery with a mean follow-up of 10 months. 28 fractures were treated with cannulated screws and 13 with a fixed angle device (DHS in 7, a cephalodmedullary nail in 5, and DCS in 1). Reduction quality, accuracy of implant placement, time to surgery, and capsular decompressive maneuvers were evaluated. 38 fractures (93%) had an excellent reduction and 3 had a fair reduction. The incidence of nonunion and osteonecrosis was evaluated.
Results: For the group as a whole, nonunion occurred in 6 of 41 fractures (15%). The nonunion rate for excellent reductions was 4 of 38 (11%), and for fair reductions 2 of 3 (67%). One patient treated with a fixed angle device developed deep infection and nonunion, and subsequently required a Girdlestone resection. Quality of reduction has been shown to influence outcomes; therefore, we chose to subanalyze the 37 patients that had excellent reductions, good implant placement, and did not develop septic failure. For this cohort, the mechanical failure rates (nonunion) were 4 of 26 (15 %) for fractures treated with screws alone, and 1 of 11 (9%) for those treated with a fixed angle device (NS). Osteonecrosis occurred in 7 of 41 fractures (17%). The osteonecrosis rates were similar for both classes of fixation devices.
Conclusions/Significance: Pauwels' Type 3 femoral neck fractures were problematic to treat. The overall nonunion rate was higher than that previously reported for femoral neck fractures. Even when excellent reduction and good implant position was obtained, the failure rates for fractures treated with cannulated screws alone was higher than that for those treated with fixed angle devices. Although not statistically significant due to the small sample size, this study documents the problematic nature of this fracture pattern and supports further larger studies to define the ideal fixation device for this fracture. This study, to our knowledge, represents the largest clinical series of purely Pauwels' 3 transcervical fractures studied to date.