The suitability of an uncemented hydroxyapatite coated (HAC) hip hemiarthroplasty stem for intra-capsular femoral neck fractures in osteoporotic elderly patients: the Metaphyseal-Diaphyseal Index, a solution to preventing intra-operative periprosthetic fracture

J Orthop Surg Res. 2011 Nov 18:6:59. doi: 10.1186/1749-799X-6-59.

Abstract

This study will seek to identify a measurable radiographic index, the Metaphyseal-Diaphyseal Index (MDI) score to determine whether intra-operative fracture in osteoporotic bone can be predicted.A 5 year prospective cohort of 560 consecutive patients, undergoing hemiarthroplasty (cemented or uncemented), was evaluated. A nested case-control study to determine risk factors affecting intra-operative fracture was carried out. The Vancouver Classification was used to classify periprosthetic fracture. The MDI score was calculated using radiographs from the uncemented group. As a control (gold standard), Yeung et al's Canal Bone Ratio (CBR) score was also calculated. From this, a receiver operating characteristic (ROC) curve was formulated for both scores and area under the curve (AUC) compared. Intra and inter-observer correlations were determined. Cost analysis was also worked out for adverse outcomes. Four hundred and seven uncemented and one hundred and fifty-three cemented stems were implanted. The use of uncemented implants was the main risk factor for intra-operative periprosthetic fracture. Sixty-two periprosthetic fractures occurred in the uncemented group (15.2%), nine occurred in the cemented group (5.9%), P < 0.001. The revision rate for sustaining a periprosthetic fracture (uncemented group) was 17.7%, P < 0.001 and 90 day mortality 19.7%, P < 0.03. MDI's AUC was 0.985 compared to CBR's 0.948, P < 0.001. The MDI score cut-off to predict fracture was 21, sensitivity 98.3%, specificity 99.8%, positive predictive value 90.5% and negative predictive value 98%. Multivariate regression analysis ruled out any other confounding factors as being significant. The intra and inter-observer Pearson correlation scores were r = 0.99, P < 0.001. JRI uncemented hemiarthroplasty has a significantly higher intra-operative fracture rate. We recommend cemented arthroplasty for hip fractures. We propose a radiographic system that may allow surgeons to select patients who are good candidates for uncemented arthroplasty, but it needs prospective validation.

MeSH terms

  • Aged
  • Aged, 80 and over
  • Arthroplasty, Replacement, Hip / adverse effects*
  • Arthroplasty, Replacement, Hip / methods
  • Biocompatible Materials / therapeutic use
  • Bone Cements / therapeutic use*
  • Case-Control Studies
  • Costs and Cost Analysis
  • Durapatite / therapeutic use
  • Female
  • Femoral Neck Fractures / diagnostic imaging
  • Femoral Neck Fractures / surgery*
  • Hip Prosthesis
  • Humans
  • Intraoperative Complications / economics
  • Intraoperative Complications / etiology*
  • Intraoperative Complications / prevention & control
  • Male
  • Osteoporotic Fractures / diagnostic imaging
  • Osteoporotic Fractures / surgery*
  • Periprosthetic Fractures / economics
  • Periprosthetic Fractures / etiology*
  • Periprosthetic Fractures / prevention & control
  • Predictive Value of Tests
  • Prognosis
  • Prospective Studies
  • Radiography
  • Risk Factors
  • Treatment Outcome

Substances

  • Biocompatible Materials
  • Bone Cements
  • Durapatite