Short term complications after revision THA with a
Modular Dual Mobility (MDM) prosthesis
Hospital for Special SurgeryWeill Medical College of
Cornell University
New York, New York
Disclosure
Research Support:National Institutes of Health
NIH/NIAMS R01-AR056802NIH/NIBIB R01-EB000744
OREFOREF Career Development Award
Smith and NephewConsultant:
Smith & Nephew
Dual Mobility
• Modular cup – Polyethylene liner
• 2 points of articulation
– CoCr insert– “Ingrowth” cup
• Multiple points of fixation
• Head:Neck ratio• Jump distance• Stability?
– 2 yrs– 79 Cases
• 1.3% Dislocation • 0% Revision rate for dislocation • 2.7% mechanical failures
• Saragaglia et al 2013 – 29 Cases revised for instability – Average FU- 46 months– 1 Redislocation
International Orthop (SICOT) 2014
• Swedish Registry- Hailer et al – 2012 – 228 pt with recurrent
instability– Lateral and Posterior approach– Mean FU 2 years (0-6 yrs)– 8% Revision rate for any reason– 2% Revision rate for dislocation
What are the short term complications after
revision THA with a MDM prosthesis?
Methods
• Hospital for Special Surgery implant billing database– Implant liner part numbers
• All sizes
– All cases reviewed• Case coding• Chart• PACS
Methods
• 379 Cases– 244 Primary THA excluded– 1 excluded
• Implant billed• MDM not implanted
• 134 Hips– 132 patients
Inclusion Criteria
All THA revisions with MDM prosthesis (2011-2013)– Acetabular revisions– Stem & acetabular revisions– Liner exchanges only
• Existing cup compatible with Co-Cr liner
– Fusion conversions– Conversion of previous hip fracture
• Hemiarthroplasty • Hip screw/DHS• IM nail
Methods
• Hospital & Clinic Charts reviewed– Further Revisions/Procedures
• Open Revisions• Closed Reductions
– Issues related to prosthesis– Issues related to revision procedure
• (complications not related to prosthesis)
• Patient contacted by phone– <6 months of follow up
(<6 months f/u was not an exclusion criteria )
Methods
• Dislocation or prosthesis related failure counted as end point
• Pt with multiple dislocations after revision were counted as 1 failure
ResultsMean Min Max Std
Age 65.5 29.0 97.0 12.7
BMI 27.4 17.2 47.3 5.7
Length of Followup (months after revision)
16.9 0 37 10.8
Left Right
61 73
Operative Side
ResultsIndication for Revision Number
Instability 52 38.8%
Acetabular Loosening 18 13.4%
Post Traumatic(DHS/Hemi/Nonunion)
13 9.7%
Acetabular Osteolysis 13 9.7%
Replant (Infection) 11 8.2%
Poly Failure/Wear 5 3.7%
ALVAL 5 3.7%
Failed Resurfacing 5 3.7%
Femoral Failure 4 2.9%
Indication Unclear 4 2.9%
Fusion Takedown 2 1.5%
Heterotopic Ossification 2 1.5%
134 100%
ResultsNumber of Previous
SurgeriesNumber of Patients
1 82 61.2%
2 25 18.7%
3 11 8.2%
4 2 1.5%
≥5 6 4.5%
Info not available 8 6%
134
ResultsProcedure Number
Cup Revision 93 69.4%
Both Component Revision
22 16.4%
Replant after Infection 11 8.2%
Conversion of Previous Hip Surgery to THA
3 2.2%
Liner Revision 3 2.2%
Revision to Total Femur 2 1.5%
134
Reoperation rate • 17 (13%) Dislocations/Cup Failure
– 14 (10%) Dislocations• 4 dislocations with + infection• 1 sciatic nerve palsy after dislocation• 1 Intraprosthetic disassociation • 1 successfully treated with a closed reduction
– 13/14 require open reduction
• 1 recurrent dislocator with metal liner dissociation
– 3 (2.2%) Loose Cups
Results• Other Surgical Complication
– 5 (3.7%) Deep infections (no dislocation)– 1 Superficial infection– 1 Fascial Dehiscence
• 1 Death – unrelated • Other Complications
– 7 Hip Pain(Groin, Iliopsoas, thigh)
– 1 Superficial wound infection– 1 Heterotopic Ossification– 1 Sciatic nerve palsy following revision-resolving
Results
• Post op instability by procedure type– 11/93 (12%) Acetabular Revision– 2/20 (10%) Both Component– 1/3 (33%) Liner Revision only
Results
• Dislocation Rate in pts revised for instability– 52 with hx of instability– 7/52 (13%) Recurrent dislocations
• 39 Patients with instability– 5/39 (13%) Recurrent dislocation
• 13 Constrained Liners revised to MDM– 2 Recurrent dislocations
Conclusion
• 18% Reoperation rate for any reason• 13% Redislocation after instability• 10% Dislocation after revision for any reason
• Pt dislocation rate after revision higher than other published reports
• Pt often required open reduction after dislocation• Closely monitor the long term outcomes of these
devices
THANK YOU
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