Presence of a nail in the medullary canal; is it enough to prevent femoral neck shortening in trochanteric fracture?

Femoral neck shortening as a sequela of internal fixation for femoral neck fractures and its effect on the coronal alignment of the limb: a pilot study

INTRODUCTION

Femoral neck shortening is a common phenomenon following osteosynthesis for femoral neck fractures, which was shown to have a negative effect on hip function. There is paucity of literature on the effect of shortening on the ipsilateral limb mechanical axis and knee coronal alignment. We hypothesized that postoperative femoral neck shortening can alter the limb's mechanical axis into valgus.

METHODS

Of 583 patients screened, 13 patients with severe neck shortening (< 10 mm) following femoral neck fracture fixation, were found eligible and agreed to participate. A full-length lower limb radiographs were obtained and radiographic parameters (offset, neck-shaft angle, HKA, mLPFA, mDLFA, mMPTFA, MAD, MAD-r) as well as functional scores were obtained.

RESULTS

Statistically significant differences in mechanical axis deviation ratio (MAD-r) were found between the ipsilateral and the contralateral extremities (0.41 ± 0.16 versus 0.55 ± 0.11, p = 0.03). A correlation between femoral neck length differences and MAD was not statistically significant although a tendency towards lateral deviation of the mechanical axis was noted (r = - 0.5, p = 0.077). A negative correlation was found between a greater difference in the femoral neck length and the SF12 score, both in the physical and the mental parts (r = - 0.69, p = 0.008; r = - 0.58, p = 0.035, respectively).

CONCLUSION

We found a more lateralized mechanical axis in limbs that demonstrated post-operative ipsilateral femoral neck severe shortening. These findings may provide a possible explanation and rationale for knee pain and perhaps for the development of knee osteoarthritis as a sequalae of femoral neck shortening. Further investigation and larger cohort, long-term studies are needed to further explore this hypothesis.

Proximal Femoral Shortening and Varus Collapse After Fixation of "Stable" Pertrochanteric Femur Fractures

OBJECTIVES

To evaluate and compare femoral neck shortening and varus collapse in stable pertrochanteric femur fractures treated with sliding hip screws (SHSs) or cephalomedullary nails (CMNs).

DESIGN

Retrospective review.

SETTING

Academic medical center.

PATIENTS

A total of 290 patients were included in the study. The average age was 82 years, and most were women. All sustained low-energy pertrochanteric femur fractures (OTA/AO A1.1, 1.2, 1.3, 2.2) treated operatively with SHSs or CMNs. Minimum radiographic follow-up was 3 months, with an average of 28 (range 3-162) months.

INTERVENTION

CMN or SHS fixation.

MAIN OUTCOME MEASURES

Varus collapse of the femoral neck-shaft angle and proximal femoral shortening.

RESULTS

Both implants allowed some varus collapse. Univariate analysis demonstrated a significantly greater portion of patients with SHSs progressed to varus collapse >5 degrees (P = 0.02), mild horizontal shortening >5 mm (P < 0.01), and severe horizontal shortening >10 mm (P < 0.01). There was no statistical difference in vertical shortening (P = 0.3). There was no difference in implant failure (P = 0.5), with failure rates of 3% for cephalomedullary implants and 5% for SHS constructs.

CONCLUSIONS

The SHS group experienced greater varus collapse and horizontal shortening. There was no difference in overall implant failure. These findings suggest that the CMN is a superior construct for maintenance of reduction in stable pertrochanteric fractures, which may lead to improved functional outcomes as patients recover.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

The effect of nail diameter on proximal femoral shortening after internal fixation of pertrochanteric hip fractures with short cephalomedullary nails

Objective

Investigate the effect of distal nail diameter on proximal femoral shortening (PFS) after cephalomedullary nailing of hip fractures.

Methods

A retrospective cohort study of 80 patients aged 50 years and older with pertrochanteric hip fractures treated with a 10 or 11 mm short cephalomedullary nail (CMN) was performed. We measured abductor lever arm shortening, femoral height shortening, and PFS.

Results

There was no difference in abductor lever arm shortening (p = 0.09), femoral height shortening (p = 0.86), and PFS (p = 0.34) between the 10 and 11 mm groups.

Conclusions

Our results suggest that distal nail diameter does not affect PFS.

Level of evidence

III.

Gait Analysis After Intertrochanteric Hip Fracture: Does Shortening Result in Gait Impairment?

OBJECTIVE

To determine the association between fracture collapse with altered gait after intertrochanteric (IT) fracture using the trochanteric fixation nail (TFN) and helical blade.

DESIGN

Prospective cohort study.

SETTING

Academic Level I trauma center.

PATIENTS

Seventy-two patients with IT hip fractures (OTA/AO 31) treated between 2012 and 2016. The average age was 79.7 years (range, 51-94 years); there were 59 women and 13 men.

INTERVENTION

All patients were treated with cephalomedullary nailing using the TFN (DePuy-Synthes, West Chester, PA) with a helical blade.

MAIN OUTCOME MEASURES

At follow-up appointments, temporospatial gait parameters were measured and recorded. Radiographs were analyzed at the time of surgery and at each follow-up visit. Amount of radiographic femoral neck shortening was measured radiographically. Patients completed the Harris Hip Score, visual analog scale for pain, Short Form-36 Physical Component Score, and Short Form-36 Mental Component Score.

RESULTS

The mean length of follow-up between the surgery and the gait analysis was 8.6 months (±0.7 months). The mean amount of shortening was 4.7 mm (±0.6 mm). Out of the 72 patients analyzed, there were 15 patients (20.8%) who shortened more than 8 mm, 7 patients (9.7%) who shortened 10 mm or more, and 2 patients (2.8%) who shortened more than 20 mm. Mean shortening was 3.0 mm for stable OTA/AO 31-A1 fractures, whereas the unstable patterns (OTA/AO 31-A2, 31-A3) demonstrated a mean shortening of 5.9 mm (P = 0.02). There was significant correlation between increased shortening and decreased cadence (P = 0.008), increased double support time (P < 0.001), decreased step length (P = 0.001), and increased single support asymmetry (P = 0.04) during gait analysis. The threshold of 8 mm of shortening predicted decreased cadence (P = 0.008), increased double support time (P < 0.001), and decreased step length (P = 0.006). Analysis of patient-reported outcome scores, including the Harris Hip Score, visual analog scale, SF-36 Physical Component Score, and SF-36 Mental Component Score, revealed no significant association with shortening.

CONCLUSIONS

Results from this study indicate that shortening after cephallomedullary nailing of IT hip fractures using the TFN with a helical blade is associated with altered gait, specifically decreased cadence, increased double support time, decreased step length, and increased single support time asymmetry.

LEVEL OF EVIDENCE

Prognostic Level II. See Instructions for Authors for a complete description of levels of evidence.

CT-measurement predicts shortening of stable intertrochanteric hip fractures

Purpose

Intertrochanteric (IT) hip fractures can be treated with sliding hip screws (SHS) or cephalomedullary nails (CMN) based on the stability of the fracture. This stability is affected by the initial impaction of the fracture which can be difficult to assess. The aim of this paper is to develop specific pre-operative computed tomography (CT) measurements of IT fractures which are predictive of post-operative shortening.

Methods

A retrospective review was performed of 141 patients with AO/OTA 31A1 or 31A2 fracture patterns, who had pre-operative radiographs and CT scans, and who were treated with a SHS or a CMN. Pre-operative and post-operative imaging of IT fractures were analyzed for those fractures that shortened ≥15 mm post-fixation.

Results

11 fractures shortened ≥15 mm with CMN being protective of shortening (6/36 SHS versus 5/105 CMN, p = 0.0268). A novel measurement made on the pre-operative CT scan called the cortical thin point (CTP) detected differences between patients with <15 mm and ≥15 mm of post-operative shortening for the SHS group (p = 0.0375). CTP was found to be a reliable predictor for post-operative shortening of ≥15 mm when a cutoff threshold of 9 mm was used in the SHS group (p = 0.0161).

Conclusions

Measuring the CTP is predictive of post-operative shortening after fixation of an IT fracture with a SHS. CMN fixation may be protective of shortening. Patients with a CTP of ≤9 mm are at risk for fracture site shortening of more than 15 mm when treated with a SHS.