Abstract
Purpose of study:
The purpose of the study is to evaluate the changes in peri-prosthetic bone mineral density following cemented and cementless total hip arthroplasty over a follow up period of 1 year.
Description of methods:
Ethics approval was sought and granted by the South African Medical Association Research Ethics Committee (SAMAREC). Patient consent for participation was obtained. Recruitment of the cohort took place over 2 years. Patients received an uncemented (Synergy) or cemented (Spectron) prosthesis as clinically appropriate. Functional status according to the University of California Los Angeles activity scale (UCLA scale) and bone mineral density as measured by Dual Energy X-ray Absorptiometry (DEXA) was assessed pre-operatively and at 3 months, 6 months and 12 months post-operatively. An independent Contract Research Organisation was used to monitor the site.
Summary of results:
As at August 2010, 59 unique patients had undergone 59 hip replacements, and 7 patients (8.5%) were still due their 12 month evaluation. The mean UCLA scored showed a marked and steady improvement post-operatively, with most of the gain demonstrated by 3 months.
When evaluating all patients, the mean pre-operative values for Gruen Zones 2, 4, and Net were significantly lower than the mean 12 month values.
When evaluating patients who received the uncemented prosthesis (n=40), the mean pre-operative values for Gruen Zones 2 and Net were significantly lower than the mean 12 month values, and the mean pre-operative values for Gruen Zones 1 and 3 were significantly higher than the mean 12 month values.
When evaluating patients who received the cemented prosthesis (n=19), the median pre-operative values for Gruen Zones 1, 2, 3, 4, 7 and Net were significantly lower than the median 12 month values.
Conclusion:
At 1 year post surgery overall bone density showed a significant increase in both the cemented and uncemented cohort.
