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