Morphological differences of proximal femoral medullary cavity in elderly patients and its effect on proximal femoral nail fixation

Abstract

Objective To investigate the morphological differences of proximal femoral medullary cavity in elderly patients with intertrochanteric fracture and its effect on the treatment efficacy of proximal femoral nail antirotation (PFNA). Methods A retrospective case series study was conducted on the clinical data of 112 elderly patients with intertrochanteric fracture of the femur from December 2012 to January 2017, including the preoperative and postoperative hip joints orthotopic X ray (including the proximal femur), lateral X ray, and pelvic orthotopic X ray films. The proximal femoral canal flare index (CFI) and the metaphyseal canal flare index (MCFI) were measured. The proportion of patients with different types of medullary cavity and the gender difference were analyzed according to Dorr typing. The fractures were classified according to the modified Evans classification. Operation time, fracture reduction quality, tip apex distance (TAD), incidence of intraoperative split fracture around the rotors, postoperative fracture reduction loss rate, weight bearing time, and fracture healing time were recorded. Results The proximal femoral canal flare index (CFI) was significantly correlated with the intramedullary diameter above the lesser trochanter, the inner diameter of the affected side medullary cavity isthmus, and metaphyseal canal flare index (MCFI) (P 0.05). In this group, the medullary cavity of proximal femur was classified by Dorr: the proportion of funnel type, normal type, and chimney type was 5.4% (6/112), 73.2% (82/112), and 21.4% (24/112), respectively. There was no significant difference in the modified Evans fracture stability among different morphological types of the proximal femoral medullary cavity. The difference of weight bearing time between normal group and chimney group was statistically significant [normal type: (21.4±16.9)d, chimney type: (45.5±11.2)d](P 0.05). Conclusions The occurrence and development of osteoporosis can cause significant changes in the morphology of proximal femoral medullary cavity, mainly manifesting as the gradual increase of the proportion of chimney type. The efficacy of PFNA in treatment of the intertrochanteric fracture is satisfactory. However, the risk of intraoperative cleavage fracture and postoperative reduction loss should be taken seriously. Key words: Hip fractures; Fracture fixation, intramedullary; Anatomy; Histology; Aged