Estimating femoral nail length in bilateral comminuted fractures using fibular and femoral head referencing

Elbow to digit measurements as a preoperative adjunct tool to aid intramedullary femoral nail selection - the rule of thumb

BACKGROUND

Intramedullary femoral nails are measured intraoperatively using fluoroscopy. This study aims to investigate whether distance from the olecranon to fingertips can be used to estimate nail length preoperatively by evaluating agreement of the two measurements. Such preoperative measurements may provide a likely range of nails needed for theatre and serve as an adjunct to intraoperative measurements.

METHODS

In 70 patients, long leg radiographs were used to make linear measurements from the piriformis fossa and greater trochanter to the distal physeal scar of the femur. These were compared to measurements from the olecranon to the tip of each digit and Bland-Altman agreement analysis was performed. Train and Trial groups were formed to develop models for estimation and to then test their accuracy.

RESULTS

Bland-Altman analysis revealed a fixed bias, indicative of average difference between measurements, of 1.4 cm when comparing the elbow-thumb length to maximum femoral nail length for piriformis fossa entry and 3.5 cm using greater trochanter entry, informing the "rule of thumb". Elbow-thumb length plus 1.4 cm or 3.5 cm predicts nail length to a range of ± one nail increment. The rule can be used to preoperatively predict a range of three nails from which there is a 94-97% likelihood the appropriate intramedullary nail would be selected.

CONCLUSIONS

The "rule of thumb" may serve as a simple to use tool for preoperative planning and a technical check to assess the "reasonableness" of intraoperative measurements before implantation of the device. It has the potential to reduce operating time and nail wastage.

Accurate Prediction of Antegrade and Retrograde Femoral Intramedullary Implant Length From Patient-Reported Height

OBJECTIVE

To determine whether patient height correlates with implant length selection of antegrade or retrograde femoral intramedullary implants.

DESIGN

Case-control Study.

SETTING

A single level 1 trauma center.

PATIENTS/PARTICIPANTS

All patients with operatively treated femoral shaft fractures from 2011 to 2017.

INTERVENTION

All fractures were treated with an intramedullary nail. Retrograde or antegrade insertion was decided at the discretion of the surgeon and fracture location.

MAIN OUTCOME MEASUREMENTS

Length of femoral implant and patient height.

RESULTS

Five hundred sixty-seven operatively treated fractures were reviewed, 322 antegrade and 245 retrograde. The correlation between patient height and actual nail length was 0.55 for antegrade implants (P < 0.01) and 0.59 for retrograde implants (P < 0.01). Separate prediction equations for nail length based on patient height were estimated for antegrade and retrograde implants and found accurate prediction of length 86% and 88% of the time, respectively.

CONCLUSIONS

Intramedullary nail length can be accurately predicted based on patient height and the technique using the equations below. This is the first study to establish a simple equation to serve as an adjunct for selecting the most appropriate length implant. This equation can be used in cases of bilateral femur fractures, templating to have appropriate sized implants in close proximity to the odds ratio, and in remote environments where surgical planning is critical for determining implant needs.

Correlation between the length from the elbow to the distal interphalangeal joint of the little finger and the length of the intramedullary nail selected for femoral fracture fixation

AIM

To determine whether there is a correlation between the length of forearm to the distal interphalangeal joint (DIPJ) of the little finger and length of antegrade intramedullary (IM) femoral nails in adults.

STUDY DESIGN AND METHODS

Measurements from the tip of the olecranon to the DIPJ of the ipsilateral upper limb was taken in 30 patients undergoing antegrade IM femoral nails. The length of the IM nails inserted was determined by intra-operative measurements using a guide wire. The two measurements were analysed for correlation and mean difference.

RESULTS

The mean forearm to DIP of little finger length was 38.86 with a standard deviation of 2.83. The mean IM length and standard deviation were 38.56 and 2.77 respectively. The difference between the two means 0.3 (95% CI). Correlation testing between the two variables shows a positive relationship (Pearson Correlation factor of 1). The scatter plot shows a positive linear relationship.

CONCLUSIONS

Length of the forearm from the tip of the olecranon to the DIP joint of the little finger represents the ideal length of IM nail for the femur. It can be readily performed with the use of a tape measure and can serve as a useful adjunct to determining ideal length in cases where the contralateral femur cannot be used.

Correlation between the forearm plus little finger length and the femoral length

PURPOSE. To assess the correlation between the forearm plus little finger length and the femoral length in 100 volunteers. METHODS. The forearm plus little finger length and the ipsilateral femoral length of 68 male and 32 female volunteers aged 19 to 55 (mean, 35.8) years were measured using a measuring tape. The forearm plus litter finger length was measured from the tip of the olecranon to the tip of the little finger, whereas the femoral length was measured from the tip of the greater trochanter to the level of proximal pole of the patella over the outer aspect of thigh. Two observers made the measurements on 2 separate occasions. Intra- and inter-observer variations were calculated. A value of 0.75 or greater indicated excellent agreement. RESULTS. The mean forearm plus little finger length and femoral length were 39.87 (SD, 2.73) and 39.85 (SD, 2.44) cm, respectively. The mean difference between these 2 measurements was 0.028 (95% CI, -0.109 to 0.165) cm. The correlation between these 2 measurements was 0.861 (p<0.001). Patient age, sex, and body mass index did not affect this correlation. The intra- and inter-observer reliability was excellent. CONCLUSION. The forearm plus little finger length correlated with the femoral length. This method is simple, radiation-free, and can be applied in day-today practice.