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Unaddressed Cam Deformity Is Associated with Elevated Joint Contact Stress After Periacetabular Osteotomy.

Publication ,  Journal Article
Scott, EJ; Thomas-Aitken, HD; Glass, N; Westermann, R; Goetz, JE; Willey, MC
Published in: J Bone Joint Surg Am
October 17, 2018

BACKGROUND: Femoral cam deformity is frequently present in patients with acetabular dysplasia. Computational modeling can be used to identify how this deformity affects joint mechanics. Our purpose was to identify the relationship between cam deformity and joint contact stress after periacetabular osteotomy (PAO). We hypothesized that cam deformity is associated with an increase in peak joint contact stress after PAO. METHODS: This was a retrospective review of patients treated for hip dysplasia with PAO without femoral osteochondroplasty. Patient-specific hip models created from preoperative and postoperative computed tomography (CT) scans were evaluated using discrete element analysis to determine maximum joint contact stress after PAO. Twenty hips with a postoperative increase in maximum contact stress were compared with 20 that demonstrated decreased maximum contact stress. Hips were assessed for cam deformity on cross-sectional imaging. Radiographic measures of acetabular dysplasia before and after PAO were assessed and compared with the change in maximum contact stress after PAO. RESULTS: There was a moderate relationship between the change in maximum contact stress and the α angle (r = 0.31; p = 0.04), and the average α angle in the hips with increased maximum contact stress was significantly different from that in the hips with decreased joint contact stress (51° ± 11.4° versus 42° ± 5.1°; p = 0.04). All 6 hips with an α angle of >60° demonstrated increased joint contact stress. CONCLUSIONS: Cam deformity is common in patients with hip dysplasia. In our study, α angles of >60° were associated with increased postoperative joint contact stress. The α angle should be assessed preoperatively, and deformity should be addressed for optimal joint mechanics after PAO. CLINICAL RELEVANCE: A reduction in joint contact stress is a proposed mechanism for the increased joint longevity following periacetabular osteotomy for hip dysplasia. Impingement from abnormal femoral offset negatively impacts clinical outcome, but this finding has not been evaluated from a biomechanical perspective previously and a threshold for performing femoral osteochondroplasty has not been established previously. This study provides biomechanical evidence supporting surgical management of femoral cam deformity for an α angle of >60°.

Duke Scholars

Published In

J Bone Joint Surg Am

DOI

EISSN

1535-1386

Publication Date

October 17, 2018

Volume

100

Issue

20

Start / End Page

e131

Location

United States

Related Subject Headings

  • Young Adult
  • Stress, Mechanical
  • Retrospective Studies
  • Postoperative Complications
  • Osteotomy
  • Orthopedics
  • Middle Aged
  • Male
  • Humans
  • Hip Dislocation
 

Citation

APA
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ICMJE
MLA
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Scott, E. J., Thomas-Aitken, H. D., Glass, N., Westermann, R., Goetz, J. E., & Willey, M. C. (2018). Unaddressed Cam Deformity Is Associated with Elevated Joint Contact Stress After Periacetabular Osteotomy. J Bone Joint Surg Am, 100(20), e131. https://doi.org/10.2106/JBJS.17.01631
Scott, Elizabeth J., Holly D. Thomas-Aitken, Natalie Glass, Robert Westermann, Jessica E. Goetz, and Michael C. Willey. “Unaddressed Cam Deformity Is Associated with Elevated Joint Contact Stress After Periacetabular Osteotomy.J Bone Joint Surg Am 100, no. 20 (October 17, 2018): e131. https://doi.org/10.2106/JBJS.17.01631.
Scott EJ, Thomas-Aitken HD, Glass N, Westermann R, Goetz JE, Willey MC. Unaddressed Cam Deformity Is Associated with Elevated Joint Contact Stress After Periacetabular Osteotomy. J Bone Joint Surg Am. 2018 Oct 17;100(20):e131.
Scott, Elizabeth J., et al. “Unaddressed Cam Deformity Is Associated with Elevated Joint Contact Stress After Periacetabular Osteotomy.J Bone Joint Surg Am, vol. 100, no. 20, Oct. 2018, p. e131. Pubmed, doi:10.2106/JBJS.17.01631.
Scott EJ, Thomas-Aitken HD, Glass N, Westermann R, Goetz JE, Willey MC. Unaddressed Cam Deformity Is Associated with Elevated Joint Contact Stress After Periacetabular Osteotomy. J Bone Joint Surg Am. 2018 Oct 17;100(20):e131.

Published In

J Bone Joint Surg Am

DOI

EISSN

1535-1386

Publication Date

October 17, 2018

Volume

100

Issue

20

Start / End Page

e131

Location

United States

Related Subject Headings

  • Young Adult
  • Stress, Mechanical
  • Retrospective Studies
  • Postoperative Complications
  • Osteotomy
  • Orthopedics
  • Middle Aged
  • Male
  • Humans
  • Hip Dislocation