LONG-TERM RESULTS OF HIP RESURFACING ARTHROPLASTY IN PATIENTS UNDER 50 YEARS OF AGE

Introduction

Hip resurfacing arthroplasty (HRA) lost its popularity because of excessive wear of the ASR M/M design. Now that causes of wear have been identified, it remains an attractive treatment option for young patients because of its bone-conserving nature, the preservation of bone mineral density, a low dislocation rate, and its biomechanical precision.

Methods

We assessed the long-term clinical outcomes of 1074 patients (1321 hips) who were implanted with hybrid Conserve^®Plus HRA, with 556 surgeries performed in patients younger than 50 years of age (average, 41.6 years) compared to 765 surgeries performed in patients 50 years or older (average, 58.1 years). 74% of the patients were male. There were no exclusion criteria. The <50 group had a larger proportion of dysplasia and hips operated during the first generation of surgical technique.

Results

The mean elapse time after surgery was 15.6 years (range 7.4 to 22.5 years). We found no difference in UCLA pain, walking and function scores between the two groups except for a slightly higher activity level in the younger group (7.4 vs. 7.2, p=0.0172). Quality of life SF-12 scores were also comparable. Although we found better survivorship rates for the group of older patients (Log-rank test p=0.0107 – Figure 1) between the younger and older patients (Table 1), this difference was largely explained by the greater proportion of dysplasia (p=0.0001) and 1^st generation hips (p=0.044) in the <50 group. The rate of post-operative complications (dislocations, sepsis, neve palsies, blood-related and others) was not significantly different between groups (p=0.3738). However, the complication rate dropped significantly (p=0.0390) in both groups from 6.4% for the first and 2^nd generations of surgical technique (n=670) to 3.8% with the 3^rd generation of surgical technique (n=651).

Conclusions

The long-term results of metal-on-metal HRA meet and even surpass the original expectations in young and active adults, with survivorship rates far superior to those reported in registries for conventional total hip arthroplasty. However, the etiologic characteristics (particulartly hip dysplasia in women of small size, but not osteonecrosis) of this demanding population also affect the results of HRA with a lower survivorship compared with that of older patients.

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