Challenges in total hip arthroplasty

Top reasons of revision or reoperation16

From a study of 1100 revised THA from 1986-2005 at a high volume teaching hospital

  • Aseptic loosening (45.3%)
  • Osteolysis/wear (15.7%)
  • Instability (15.7%)
  • Infection (10.7%)
  • Periprosthetic fracture (5.7%)

"The success of hip arthroplasty is likely to be compromised if technical aspects of the surgery for appropriate component positioning and critical protocols to minimize complications such as infection are not given the proper attention.17"


Surgical Experience

Principal investigators

  • Henrik Malchau, MD
  • Douglas E. Padgett, MD
  • Jon Dounchis, MD
  • Richard Illgen, MD
  • Robert C. Marchand, MD

Methodology

  • 120 (110 were evaluated) robotic-arm assisted THA cases from 4 institutions’ post-op A/P pelvis and lateral X-rays were evaluated using Martell hip analysis software for cup positioning.

Results

  • Based on Mako data (3-D), 96% of robotic-arm assisted THA cases were inside the Callanan safe zone (30°- 45° inclination and 5°-25° version).
  • The 95% predictive interval was ±3.5°for inclination and ± 3.6° for version using the intra-operative recorded position of the cup by the robotic-arm.
Pre-op plan average ± std. dev.
Intra-op plan robotic-arm measurement average ± std. dev.
Radiographic Measurement average ± std. dev.
Inclination
40.0º ± 1.2º
39.9º ± 2.0º
40.4º ±4.1º
Version
18.7º ± 3.1º
18.6º ± 3.9º
21.5º ± 6.1º
Count (n)
119
119
110

Principal investigators

  • Benjamin G. Domb, MD

Methodology

  • Matched groups of 50 Mako THAs and 50 manual THAs by a single surgeon using a posterior approach were analyzed radiographically for cup positioning.

Results

  • 100% of robotic-arm assisted cups were placed within the Lewinnek “Safe Zone” for anteversion and inclination compared to 80% of manual cases.
  • 92% of robotic-arm assisted cups were placed within the Callanan “Safe Zone” for anteversion and inclination compared to 62% of manual cases.

Principal investigators

  • Carlos Suarez-Ahedo, MD
  • Benjamin Gilbert Domb, MD

Methodology

  • 14 patients
    • 57 conventional THA (cTHA)
    • 57 robotic-arm assisted THA (RTHA)
  • Matched for femoral head size
  • Acetabular cup diameter and the native femoral head diameter were used to infer the relative amount of bone stock removed

Results

  • Indicated greater preservation of bone stock using RTHA compared to CTHA
  • “RTHA allowed for the use of smaller acetabular cups in relation to the patient’s femoral head size, compared to CTHA.”

Methodology

  • Dr. Douglas Padgett, from Hospital for Special Surgery, who has robotic experience, performed twelve cadaveric THA (six THAs using Mako Robotic-Arm Assisted Total Hip technology and six underwent manual THAs)

Results

  • The root mean square (RMS) error for the robotic-assisted surgery was within 3° for cup placement and within one mm for leg length equalization and offset based on comparisons of pre- and post-operative CT scans
  • The RMS error for manual implantation compared to robotic-assistance was five times higher for cup inclination and 3.4 times higher for cup anteversion (p>0.01)

Principal investigator

  • Seth Jerabek, MD

Methodology

  • Five surgeons performed 21 THAs on cadaveric hips.
  • Pre-operative CTs of each hip were used to plan the cup, stem, head diameter, neck length, and liner.
  • Post-op CTs were compared with pre-operative planned and intra-operatively captured values.


Patient outcomes

Outcomes after primary total hip arthroplasty: manual compared with robotic-assisted techniques21-23

Principal investigators

  • Richard Illgen, MD

Methodology

  • 1st 100 consecutive manual THA cases (2000)
  • Last 100 consecutive manual THA cases (2011)
  • 1st 100 consecutive robotic-arm assisted THA cases (2012)
  • Radiographic and clinical outcomes assessment

Results

  • Robotic-arm assisted THA demonstrated significantly higher modified Harris Hip Score and UCLA activity level compared with manual THA at a minimum 1 year follow up.
  • Estimated blood loss was reduced in the rTHA patients.
  • Robotic-arm assisted THA improved both acetabular abduction and anteversion accuracy and achieved reduced early dislocation rates and improved rates of limb length discrepancy compared with manual THA.
First manual 100
Last manual 100
First robotic-arm 100
31% in target zone
45% in target zone
76% in target zone
5% dislocation
(4/5 anterior)
3% dislocation
(2/3 anterior)
0% dislocation
3% fractured liners
0% fractured liners
0% fractured liners