Safety and Efficacy of Uncemented Acetabular Component: 5–9 Year Follow-up

Introduction

Total hip arthroplasty (THR) is one of the most successful procedures performed today. Uncemented acetabular components have by and large replaced cemented cups. As such, optimal fixation, bony ingrowth with longevity, and safety is highly demanded. In this study, we look at the safety and efficacy of the Stryker® Trident PSL™ acetabular component based on radiographic and clinical analysis.

Materials and Methods

We looked at 860 consecutive patients between 2003 and 2007. Of these, 231 consecutive patients had a minimum 5 year follow up. All cases were for degenerative joint disease (DJD), except 2 for dysplasia, 1 for avascular necrosis (AVN), 1 femoral neck nonunion. Average Hospital for Special Surgery (HSS) hip scores at final follow up were recorded. Radiographic analysis included classification based on Delee and Charnley's zones 1–3. Osseointegration was assessed based on presence of SIRCAB (stress induced reactive cortical hypertrophy of bone), demarcation around the implant, stress shielding, presence of radial trabeculae, absence of radiolucency, type of bearing, presence of preoperative protrusion, violation of Kohler's line. EBRA software was used to assess acetabular inclination and version.

Results

Of 231 hip replacements analyzed, 114 were male, 117 were female. The average age was 63 (range 33–87); height was 67.5 inches; BMI was 27; 3 patients had a preoperative diagnosis of DDH, 2 had AVN, 1 femoral neck nonunion, and 1 case of rheumatoid arthritis (RA), with the remainder of patients diagnosed with DJD. cup abduction angle was 41.7° with average of 17.4° of anteversion. Average HSS functional score was excellent at latest follow up was 34, with most patients not relying on any assistive devices; There were no revisions performed due to mechanical failures or due to failure to osseointegrate. Complications include 1 infection (0.43%); and 4 dislocations (1.73%).

Osseointegration was measured by separating the acetabulum into DeLee and Charnley zones and assessed by analyzing:

1. a)

   stress induced hypertrophic reaction of cortical bone (SIHRCaB): zone 1 (75.8%), zone 2 (11.7%), zone 3 (51.9%)

2. b)

   Radial trabeculae: zone 1 (94.8%), zone 2 (93.5%), zone 3 (92.6%)

3. c)

   Absence of radiolucency: zone 1 (96.1%), zone 2 (97%), zone 3 (96.1%)

No association of bearing surfaces to survivorship was noted as metal femoral heads were used in 72.7% of cases while a ceramic bearing was used in 25.1%.

Conclusion

The Trident PSL acetabular component was examined in a large, consecutive series by a single surgeon with a minimum 5–9 year follow up. We have demonstrated excellent radiographic osseointegration at latest follow up with no mechanical failures, high survivorship, and excellent clinical outcome scores. It continues to be a reliable option for primary acetabular reconstruction.