Tips and tricks to avoid implant failure in proximal femur fractures treated with cephalomedullary nails: a review of the literature

Trust But Verify: Design Differences in The Prevention of Targeting Errors in Cephalomedullary Nails

OBJECTIVES

To evaluate insertional damage on explanted cephalomedullary nails and to differentiate typical from atypical wear to characterize outliers.

DESIGN

Therapeutic.

SETTING

Level II trauma center.

PARTICIPANTS

Patients who underwent removal of an implanted cephalomedullary nail for any reason from 2015 to 2023.

METHODS

Inspection of implants was performed at ×1000 magnification with a light microscope. Benchtop testing was performed with Gamma3, Gamma4, Intertan, TFN, and TFNa instrumentation.

RESULTS

One hundred nine cephalomedullary nails were inspected. Insertional damage was observed in more than 95% of the implants recovered. In 34% (37 of 109) of implants, damage to the proximal aperture was severe enough to cause a chamfer or "notch." Chamfers were also encountered along the distal locking aperture in short stem implants in 44% (19 of 43). Guidewire chamfers to the proximal implant external to the aperture and damage to preinserted set screws were outliers. Evidence of set screw fracture or deformity was encountered in 12 specimens. Four anomalous set screw variants were encountered within 1 implant design, each variant exhibiting maltracking with deployment that could result in malfunction.

CONCLUSIONS

Insertional damage to cephalomedullary implants was encountered routinely among the explants and should not always be categorized as preventable surgical error. Surgeons should be familiar with technical and design factors that contribute to chamfering of implants to reduce failures.

LEVEL OF EVIDENCE

Therapeutic, Level III.

Comparison of augmentation effects of medial buttress plate versus trochanteric lag screw in the cannulated screw fixation of Pauwels type III femoral neck fractures: A retrospective clinical study

OBJECTIVE

This study aimed to compare the effects of a medial buttress plate (MBP) or a trochanteric lag screw (TLS) to augment cannulated screws (CSs) in fixing Pauwels type III femoral neck fractures.

METHODS

This retrospective study included 58 patients (21 female, 37 male; mean age=46 years; age=19-64 years) treated by CSs for Pauwels type III femoral neck fractures from 2014 to 2017. All the patients were divided into 2 groups based on the internal fixation patterns: the MBP-augmented group (group A, n=26) and the TLS group (group B, n=32). The mean age was 47 (range=24-57) years in group A and 45 (range=19-64) years in group B. The operation time, intraoperative blood loss, reduction quality, Harris score, and postoperative complications were recorded and compared between both groups.

RESULTS

All patients were followed up for an average of 44.8 months in group A and 47.3 months in group B (P=.406). No significant difference was noted in reduction quality (P=1.000). However, group A had a longer operation time (100.2 vs. 64.3 minutes, P < .001) and greater intraoperative blood loss (153.1 vs. 30.0 mL, P < .001) than group B. At the final follow-up, the union rate was equal between group A (96.2%) and group B (90.6%) (P=.760). The mean bone union time was 21.6 weeks in group A and 23.6 weeks in group B (P=.431). The delayed union rate was lower in group A (0%) than in group B (15.6%) (P < .001). The incidence of postoperative complications in terms of implant failure (7.7% vs. 28.1%, P=.048) and femoral neck shortening (7.7% vs. 28.1%, P=.048) were lower in group A than in group B. No significant difference was noted in avascular femoral head necrosis (P=1.000) and the Harris score (P=.659) between the 2 groups.

CONCLUSION

In the surgical treatment of Pauwels type III femoral neck fractures, medial buttress plating can offer fewer complications but equal avascular femoral head necrosis rate and functional outcome compared to trochanteric screw application.

LEVEL OF EVIDENCE

Level III, Therapeutic study.