Abstract
Femoral bone preservation is an important consideration in total hip replacement for those patients expected to outlive the success of their primary procedure. A clinical study was initiated to assess the performance of a new, ultra-short, cementless femoral implant that is sited in the region of the femoral neck.
This two-centre study, conducted in Australia and Germany, was approved by the ethics committees and regulatory authorities in both countries. Patients aged between 25 and 65 with non-inflammatory arthritis were included subject to review against the detailed study selection criteria and the provision of written informed consent.
Patients were assessed pre-operatively using the Harris Hip Score and Oxford Hip Score. These scores were repeated and standard radiographs taken at 3, 6, 12 and 24 months follow-up. Radiostereometric analysis (RSA) was employed to monitor the in-vivo femoral implant stability. The Oxford Hip was additionally collected at 36 and 48 months.
Forty-one patients, 23 males and 18 females, received the SILENT™ femoral implant in primary total hip replacement surgery between January and November 2003. The mean age was 50.4 years (range 26–65) with an average BMI of 26.6 (Range 19–37). The diagnoses included osteoarthritis (68%), AVN (15%), DDH (7%), post-infection osteoarthritis (5%) and others (5%).
The average Harris Hip Score increased from 54.3 (Range 26–80) pre-operatively to 95.0 (Range 46–100) at 24 months. This improvement was supported by the patient’s view with the mean Oxford Hip Score data changing from a pre-operative level of 38.9 (Range 19–52) to a 4-year average of 13.2 (Range 12–27).
The radiographic performance is also positive with only one patient having evidence of a radiolucent line on the latest x-rays at 24 months however this is non-progressive and has been present since 6 months post-op. RSA data shows the mean values for the translations of the implant and distal tip in any of the three axes to be low out to 2 years follow-up indicating a high degree of stability in this critical post-operative period.
No revisions of the SILENT™ implant have been undertaken to date.
Early prosthetic stability is acknowledged as a critical success criterion for any new femoral implant being introduced into clinical practice. This has been demonstrated for a new, ultra-short, femoral implant thereby presenting a new solution for patients who could benefit from healthy bone preservation at the time of primary surgery.
The abstracts were prepared by David AF Morgan. Correspondence should be addressed to him at davidafmorgan@aoa.org.au
Declaration Of Interest: c: In relation to the conduct of this study, one or more the authors have received, or are likely to receive direct material benefits.
