Abstract
Purpose: This multicentric retrospective study was conducted to search for indications of femoral revision with a custom-made non-cemented implant.
Material and methods: We collected files on femoral revisions using custom-made implants among our working group and among surgeons having a certain experience between 1989 and 1991. Twenty-one patients (13 men and 10 women), mean age 50.1 years (24–81) were operated. This was the first revision for 14, the second for six, and the third for two. Mean follow-up was 35.4 years. The implant was coated with hydroxyapatite in the proximal zone with optional distal locking except for the first cases. The implant was used when the usual implants were poorly adapted. Data acquisition was achieved with previous calibrated computed tomography. The problem was to distinguish residual bone from cement or the prior implant. Information was exchanged between the engineer and the surgeon in order to define the stem shape and anchorage. Regular clinical follow-up was performed, noting the Postel Merle d’Aubligné score. The radiographic assessment focused on the absence of prosthesis descent and lucent lines.
Results: The PMA score improved from 9.6 (6–14; 2.4; 4.26; 2.91) to 14 (8–18; 4.61; 5.05; 4.25). Complications were dislocation in three hips, one requiring cup replacement and the other neck replacement. Early descent of the femoral stem was also noted in one hip which required revision. Late descent at 13 years was managed by a simple procedure in one hip (SOFCOT stage I).
Discussion: The early failures were related to the severity of the initial lesions (or rather their underestimation) and to defective initial distal stabilisation. Late failures resulted from the absence of bioreactive coating. We have had no experience with impacted grafting. The indication for custom-made implants are exceptional (less than 2% of our revisions) and can be divided into four categories: extramedullary (very long neck/varus) the implant avoiding the use of balls; extrapolation (femur too small or too large requiring under- or oversized implant); dysmorphism (excessive curvature, osteotomy or fracture sequelae, narrow metaphysic with wide diaphysis); gap filling (weight-bearing zone).
Conclusion: The advantage of a custom-made implant is the choice of anchorage and the simplification of the operative procedure. It is often the only solution in complex situations but requires close collaboration with the engineer (virtual intervention) and implies significant cost.
Correspondence should be addressed to SOFCOT, 56 rue Boissonade, 75014 Paris, France.
