Increased Fracture Collapse after Intertrochanteric Fractures Treated by the Dynamic Hip Screw Adversely Affects Walking Ability but Not Survival

Abstract

In osteoporotic hip fractures, fracture collapse is deliberately allowed by commonly used implants to improve dynamic contact and healing. The muscle lever arm is, however, compromised by shortening. We evaluated a cohort of 361 patients with AO/OTA 31.A1 or 31.A2 intertrochanteric fracture treated by the dynamic hip screw (DHS) who had a minimal follow-up of 3 months and an average follow-up of 14.6 months and long term survival data. The amount of fracture collapse and shortening due to sliding of the DHS was determined at the latest follow-up and graded as minimal (<1 cm), moderate (1-2 cm), or severe (>2 cm). With increased severity of collapse, more patients were unable to maintain their premorbid walking function (minimal collapse = 34.2%, moderate = 33.3%, severe = 62.8%, and p = 0.028). Based on ordinal regression of risk factors, increased fracture collapse was significantly and independently related to increasing age (p = 0.037), female sex (p = 0.024), A2 fracture class (p = 0.010), increased operative duration (p = 0.011), poor reduction quality (p = 0.000), and suboptimal tip-apex distance of >25 mm (p = 0.050). Patients who had better outcome in terms of walking function were independently predicted by younger age (p = 0.036), higher MMSE marks (p = 0.000), higher MBI marks (p = 0.010), better premorbid walking status (p = 0.000), less fracture collapse (p = 0.011), and optimal lag screw position in centre-centre or centre-inferior position (p = 0.020). According to Kaplan-Meier analysis, fracture collapse had no association with mortality from 2.4 to 7.6 years after surgery. In conclusion, increased fracture collapse after fixation of geriatric intertrochanteric fractures adversely affected walking but not survival.

Various factors influencing the outcome in DHS fixation of Intertrochanteric fractures

“…The statistical software used was SPSS. The study material was processed and analyzed using SPSS for windows (11) . Chisquare test, Independent t-test and Paired t-test were used to evaluate the significance of the differences.…”

“…Thus, for a DHS to work efficiently without excessive collapse the contact area between the ends has to be maximum and to attain that, the well-known regions are posterior medial calcar, the lateral wall and the anteromedial region. Thus, excessive fracture collapse in varus position following loss of bony support is due to severe fracture angulation, medialisation of proximal fragment and lateral wall fracture (1,11) . Anatomical reduction at the time of surgery is achieved by buttressing the lateral wall14.…”

CT-measurement predicts shortening of stable intertrochanteric hip fractures

“…A recent study found that the greater the shortening, the less likely the patient was able to return to premorbid walking levels at an average follow up of 14 months. 13 Another study looking at CMN fixation of IT fractures in the elderly demonstrated that a greater amount of lag screw sliding was correlated with worse functional outcomes on the SF-36 Survey and increased scores on the Visual Analog Scale. 12 While a clear threshold of symptomatic limb-shortening after hip fractures is still not known, ambulatory patients are more likely to be symptomatic when their fracture settles substantially.…”

“…11 However, too much settling may cause a diminished abductor level arm and a limb length discrepancy (LLD) which are associated with worse https://doi.org/10.1016/j.jor.2018.08.044 Received 11 June 2018; Accepted 25 August 2018 T functional outcomes, albeit no decrease in survival. 12,13 A symptomatic threshold of shortening has not been defined for the ambulatory hip fracture population, but LLDs have been extensively studied for the similarly-aged hip arthroplasty population. A post-operative LLD of greater than 10 mm has been shown to lead to lower Oxford Hip Scores and physical function three years after total hip arthroplasty.…”

Proximal Femoral Nail Unlocked versus Locked (ProFNUL): a protocol for a multicentre, parallel-armed randomised controlled trial for the effect of femoral nail mode of lag screw locking and screw configuration in the treatment of intertrochanteric femur fractures

“…In the dynamic mode, fracture collapse occurs under physiological loading, resulting in macro and micromotion of the fracture fragments as well as compression/apposition of fracture fragments,41–43 desired to stimulate fracture healing. However, excessive sliding of the lag screw has been shown by some authors to lead to mechanical complications and negatively affect patient function 44–46…”