Robotic-arm assisted total hip arthroplasty results in smaller acetabular cup size in relation to the femoral head size: a matched-pair controlled study

Hip Int. 2017 Mar 31;27(2):147-152. doi: 10.5301/hipint.5000418. Epub 2017 Mar 21.

Abstract

Purpose: To compare the acetabular component size relative to the patient's native femoral head size between conventional THA (CTHA) approach and robotic-arm assisted THA (RTHA) to infer which of these techniques preserved more acetabular bone.

Methods: Patients were included if they had primary osteoarthritis (OA) and underwent total hip replacement between June 2008 and March 2014. Patients were excluded if they had missing or rotated postoperative anteroposterior radiographs. RTHA patients were matched to a control group of CTHA patients, in terms of preoperative native femoral head size, age, gender, body mass index (BMI) and approach. Acetabular cup size relative to femoral head size was used as a surrogate for amount of bone resected. We compared the groups according to 2 measures describing acetabular cup diameter (c) in relation to femoral head diameter (f): (i) c-f, the difference between cup diameter and femoral head diameter and (ii) (c-f)/f, the same difference as a fraction of femoral head diameter.

Results: 57 matched pairs were included in each group. There were no significant differences between groups for demographic measures, femoral head diameter, or acetabular cup diameter (p>0.05). However, measures (i) and (ii) did differ significantly between the groups, with lower values in the RTHA group (p<0.02).

Conclusions: Using acetabular cup size relative to femoral head size as an approximate surrogate measure of acetabular bone resection may suggest greater preservation of bone stock using RTHA compared to CTHA. Further studies are needed to validate the relationship between acetabular cup size and bone loss in THA.

Publication types

  • Comparative Study

MeSH terms

  • Acetabulum / diagnostic imaging
  • Acetabulum / surgery
  • Adult
  • Aged
  • Case-Control Studies
  • Female
  • Femur Head / diagnostic imaging
  • Femur Head / surgery
  • Follow-Up Studies
  • Hip Prosthesis*
  • Humans
  • Male
  • Middle Aged
  • Osteoarthritis, Hip / diagnostic imaging
  • Osteoarthritis, Hip / surgery*
  • Prosthesis Design*
  • Prosthesis Failure
  • Recovery of Function
  • Retrospective Studies
  • Risk Assessment
  • Robotic Surgical Procedures / adverse effects
  • Robotic Surgical Procedures / methods*
  • Severity of Illness Index
  • Treatment Outcome