Is rotation the mode of failure in pertrochanteric fractures fixed with nails? Theoretical approach and illustrative cases

Clockwise torque results in higher reoperation rates in left-sided femur fractures

PURPOSE

Effects of clockwise torque rotation onto proximal femoral fracture fixation have been subject of ongoing debate: fixated right-sided trochanteric fractures seem more rotationally stable than left-sided fractures in the biomechanical setting, but this theoretical advantage has not been demonstrated in the clinical setting to date. The purpose of this study was to identify a difference in early reoperation rate between patients undergoing surgery for left- versus right-sided proximal femur fractures using cephalomedullary nailing (CMN).

MATERIALS AND METHODS

The American College of Surgeons National Surgical Quality Improvement Program was queried from 2016-2019 to identify patients aged 50 years and older undergoing CMN for a proximal femoral fracture. The primary outcome was any unplanned reoperation within 30 days following surgery. The difference was calculated using a Chi-square test, and observed power calculated using post-hoc power analysis.

RESULTS

In total, of 20,122 patients undergoing CMN for proximal femoral fracture management, 1.8% (n=371) had to undergo an unplanned reoperation within 30 days after surgery. Overall, 208 (2.0%) were left-sided and 163 (1.7%) right-sided fractures (p=0.052, risk ratio [RR] 1.22, 95% confidence interval [CI] 1.00-1.50), odds ratio [OR] 1.23 (95%CI 1.00-1.51), power 49.2% (α=0.05).

CONCLUSION

This study shows a higher risk of reoperation for left-sided compared to right-sided proximal femur fractures after CMN in a large sample size. Although results may be underpowered and statistically insignificant, this finding might substantiate the hypothesis that clockwise rotation during implant insertion and (postoperative) weightbearing may lead to higher reoperation rates.

LEVEL OF EVIDENCE

Therapeutic level II.

Coronal shear fractures of the femoral neck: a comparison with basicervical fractures

PURPOSE

We propose coronal shear fracture of the femoral neck (CSFF) as a new type of fracture that differs from a basicervical fracture. This study aimed to present the incidence of CSFF and compare its clinical characteristics and outcomes with those of basicervical fractures.

METHODS

In this multicenter retrospective cohort study, 2207 patients with hip fractures were identified using computed tomography (CT), 17 and 27 patients were diagnosed with CSFF (CSFF group) and basicervical fractures (basicervical fracture group), respectively. The primary outcome was reoperation, while the secondary outcomes were postoperative radiographic findings, ambulatory ability, and 1-year mortality rate. These outcomes were compared between the two groups. We also conducted diagnostic reliability tests for these fractures using the Cohen's kappa coefficient.

RESULTS

The incidence of CSFF and basicervical fractures in the 2207 patients were 0.77% and 1.22%, respectively. The inter-and intra-observer agreements for the diagnosis were almost perfect. The comorbidity score was significantly higher in the CSFF group than in the basicervical fracture group. No reoperations occurred in both groups. There were no significant intergroup differences in the postoperative radiographic findings. The 1-year mortality rate was higher in the CSFF group than in the basicervical fracture group (38.5% vs. 5.3%; odds ratio: 11.9, 95% CI: 1.2-118.5; p = 0.025).

CONCLUSION

This study presents the definition and incidence of CSFF with a high diagnostic reliability. Patients with CSFF had similar reoperation rate postoperative radiographic outcomes to basicervical fractures, while 1-year mortality rate was high.

Comparing the rates and modes of failure of two third generation cephalomedullary nail systems in the treatment of intertrochanteric hip fractures

INTRODUCTION

Cephalomedullary (CMN) implants are commonly used to address elderly intertrochanteric hip fractures. Multiple CMN implant systems exist with subtle variation between manufacturers. Multiple modes of CMN failure have been described in the literature. The present study assessed the local modes and rates of construct failure (nail fracture, cut-out and non-union) of two such implants, after a change in implant supply provided the opportunity for retrospective comparison. Additional investigation was undertaken to assess whether any predictors of failure could be identified based on common radiographic measurement parameters.

METHODS

Based on local implant records, all consecutive patients who suffered an intertrochanteric fracture, treated at a tertiary care hospital with a cephalomedullary nail from January 2014 to January 2018 were included. Patients were excluded if they received a CMN for pathologic fracture. Within the collection period all patients received either a Synthes Trochanteric Fixation Nail (TFN) or Zimmer Natural Nail (ZNN). Patients were retrospectively assessed for fracture reduction and implant technique parameters at the time of initial surgery. Radiographic data were assessed at minimum two years post-operatively to assess for union. Patient demographic data was followed to assess rate and mode of failure.

RESULTS

Six hundred and sixty-two patients were included in the study, from which a propensity matched cohort was derived. Comparing across equivalent cohorts, no differences in the rate or mode of construct failure were identified between the TFN and ZNN. When assessing the entire cohort we observed 39 construct failures (5.9%), which included 31 instances of nail cutout (4.7%), 4 episodes of nail fracture (0.6%) and 4 failures related to non-union (0.6%). Tip to apex distance, sagittal malalignment and Cleveland zone were identified as significant predictors of nail failure.

CONCLUSION

No difference in rates or modes of failure were identified between the TFN and ZNN constructs. Similar to previous reports we again identified the impact of tip to apex distance on construct failure and further identified Cleveland zone and sagittal malalignment as significant risks for failure.

Conventional versus helical blade screw insertion following the removal of the femoral head screw: a biomechanical evaluation using trochanteric gamma 3 locking nail versus PFN antirotation

OBJECTIVE

When a hip screw needs to be changed, choosing between the conventional (C-type) and helical blade (H-type) types is difficult. In this biomechanical study, we compared these two screw types relative to the type of the initial screw used.

METHODS

C- or H-type screws were inserted (leading screw) in three types of polyurethane bone models (Sawbone, Pacific Research Laboratories, Inc., Washington, USA: 130 × 180 × 40 mm) of different bone mineral densities (pounds per cubic feet [PCF] 5, 80 kg/m³; PCF 10, 160 kg/m³; and PCF 15, 240 kg/m³), and then successively or alternately inserted (following screw) after the leading screw removal. An original model (original C and H) of a leading screw without removal was created as a control. The strengths of resistance to pullout (PO) and rotational stress were measured. For each experimental condition, there were 30 experimental models.

RESULTS

The original C screw was superior in PO strength, and the original H-type screw was superior in rotational strength. When the C- or H-type screw was the leading screw, using the C-type screw again as the following screw (C1-C2, H1-C2) showed the greatest resistance to PO, and using the H-type screw as the following screw (C1-H2, H1-H2) showed superior resistance to rotational strength. However, the rotational strength of the C2 screw decreased by more than 50% compared with that of the original C screw. Moreover, the PO and rotational strengths of the H2 screw decreased to less than 30% overall compared with those of the original H screw.

CONCLUSION

The H-type screw should be used for second-time screw insertion procedures in cases where it is difficult to choose between PO and rotational strengths.

A unique cause of Gamma 3 cut-out: A case report and literature review

Gamma 3 nail is a wide spread intramedullary device for fixation of per trochanteric fractures. Cut out of the lag screw is the most common complication of this implant. We present a 62-year-old female patient, who underwent a total hip arthroplasty following cut out of a Gamma 3 nail in the femoral neck. The cause of the cut out in our case is actually unique. Our intraoperative findings accompanied with the radiographic evaluation argue that the malposition of the set screw was the cause of failure, due to the rotational instability of femoral head-lag screw unit. We present this case with detailed description, highlighting the proper use of this specific nail and appose a brief literature review.