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

Ehud Hamburger, Nir Cohen, Yoav Rosenthal, Bar Mazilis, Michael Drexler, Shai Shemesh*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

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.

Original languageEnglish
Pages (from-to)723-729
Number of pages7
JournalArchives of Orthopaedic and Trauma Surgery
Volume144
Issue number2
DOIs
StatePublished - Feb 2024

Keywords

  • Femoral neck shortening
  • Fractures
  • Knee
  • Mechanical axis deviation
  • Valgus

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