Mismatch of short straight proximal femur nails with anterior bow of femur in Indian population- A radiological and functional analysis

Abstract

IntroductionIntra-medullary devices are the most common mode of fixation of inter-trochanteric fractures. Short proximal femur nails (PFN) used for fixing these fractures, unlike the long nails, are non-anatomic and are usually straight with no curvature in antero-posterior plane. As a result, there is always a chance of the nail tip impinging against the anterior cortex of femur. Materials and methodsA total of 80 patients with trochanteric fractures (AO 31A2 and 31A3), operated with short PFN, were followed up retrospectively and prospectively from 2019 to 2021, for a period of 6 months. All fractures were fixed with PFNs, with nails ranging from 170 to 250 mm. Radiological analysis was done on hip lateral X-rays (taken at 6 months) using Angle at Distant Axis (ADA) and Nail Tip Position (NTP). Functional outcome analysis was done using Harris Hip Score. Patients were graded into 2 groups according to ADA (ADA>4° and ADA<4°). Incidence of anterior thigh pain was noted in patients on follow up and was statistically evaluated with nail size, nail diameter, ADA and NTP. ResultsMean ADA was 4.19° ± 1.45; mean NTP grade was 1.98 ± 1.11. Mean nail size was 201.87 mm with a mean nail diameter of 9.76 mm. Twenty patients complained of anterior thigh pain on follow-up. Twenty-five patients had NTP grade 3 or above of which 16 complained of anterior thigh pain (p < 0.001). Fifty-five patients had nail diameter of 10 mm or above of which 14 had anterior thigh pain (p < 0.01). Fifty-three patients had a nail length of 200 mm or above of which 16 patients complained of thigh pain on follow up (p < 0.01). ConclusionThere is a mismatch of short PFNs with anterior bow of femur. Use of shorter nails with narrow diameters will avoid this mismatch to an extent.