Evaluation of Hip Abductor Function Following Piriformis Fossa Entry Antegrade Nailing in Isolated Diaphyseal Femur Fractures at Kenyatta National Hospital

Abstract

Background: A standard method of femur shaft fractures fixation is using trochanteric entry antegrade nails. Studies have highlighted the pros and cons of trochanteric entry nails (TEN) and piriformis entry nails (PEN). Many authors have expressed faster union rates, good trochanteric alignment, shorter length of surgery, shorter duration of radiation, and better functional outcomes of TEN than PEN. Very few studies have unequivocally addressed hip abductor function to state if indeed piriformis entry damages hip abductors. In our local setup, many surgeons, including those under training, perhaps due to lack of fluoroscopy, ream the femur fractures in a retrograde manner from the fracture site and then introduce nails in an antegrade fashion through a piriformis entry point. Evaluation of hip abductor function following fixation of femur fracture with piriformis entry nail is necessary to establish and quantify the damage this procedure causes the hip abductor. There are no local studies available on this. Objective: The study aimed to establish the function of hip abductors among patients with diaphyseal femur fractures post piriformis entry nailing. Study Design: Prospective cohort study. Study Setting: Kenyatta National Hospital, Orthopedic Outpatient Clinics Methodology: Sixty-four patients who underwent fixation of fracture femur were recruited from the clinics to establish the proportion of patients and degree of hip abductor dysfunction following fracture fixation at six weeks and twelve weeks. The patients were assessed based on their gait, hip abductor range of motion, and the power of the hip abductors graded based on their ability to resist elastic loop bands. Values were obtained from the operated and the non-operated limb and compared.

Results: The mean age was 31.75, SD 8.54, Median 31.5 Range 19 – 52. Males were 45 (75.0%) while females were 15 (25.0%). Left sided injuries were 30 (50.0%) similar to right 30 (50.0%). AO32 class A were 19 (31.7%), class B 29 (48.3%), class C 12 (20.0%). The injured limbs had significantly less MRC scores when assessing power. Similarly, for the right injured limb, there was a significant increase in MRC score (p=0.012) from 6 weeks to 12 weeks. Despite an MRC power increase in the left injured limb, it was not statistically significant (p=0.089). The injured limbs had significantly less hip abductor ROM both at six and 12 weeks (Right injured limb, p = 0.0034, & p = 0.0361) and left (p = 0.007 & 0.039). However, there were no statistically significant increase in hip abductor range of motion between 6 and 12 weeks. In terms of Trendelenburg gait, there were significant differences between the normal vs the abnormal limbs, as well as between 6 weeks and 12 weeks. There was significant reduction in number of patients with a positive Trendelenburg sign from 60 to 54 at 6 weeks and 12 weeks (p=0.014). There was significant reduction in wasting between 6 weeks and 12 weeks in patients with right injured limb (p = 0.008) and no significant change in those with left injured limb. Comparing right and left limbs abductor hip strength with the use of loop elastic bands , there were significant differences in right injured limb at six weeks and 12 weeks (p values <0.001 and 0.001 respectively) and left injured limb (p 0.019 and 0.004). However, no significant differences were notable when comparing between 6 weeks and 12 weeks. There was a reduction in usage of all walking aids, from 6 weeks to 12 weeks.

Significance of the study: This study investigated the hip abductor function following piriformis entry nailing of diaphyseal fractures of femur. Despite the frequent use of antegrade nailing in fracture femur fixation, the degree of abductor dysfunction was significant at 6 weeks with marked improvements at 12 weeks. Rehabilitation techniques could improve abductor dysfunction after antegrade femoral nailing.