The 3–6 year results of a modular nonce mented ..
With an increasing number of primary hip replacements being performed every year, the burden of revision hip arthroplasty, for septic and aseptic loosening, recurrent dislocation or periprosthetic fracture, is also increasing. In recent years, different approaches to revising the femoral prosthesis have emerged; including both cemented and cementless techniques. With a stable cement mantle and good bone quality, or through the use of impaction bone grafting when bone stock is lacking, it is possible to re-cement a femoral prosthesis. Alternatively, a cementless modular femoral prosthesis may be used, providing the surgeon with further options for restoring leg length, hip offset, anteversion and stability. Studies evaluating the use of modular cementless prostheses have so far been limited to midterm studies, with results comparable to primary hip arthroplasty. There are some concerns, however, regarding tribological complications such as stem fracture, corrosion, and failure, and long-term studies are required to further evaluate these concerns. This review outlines the current evidence for the use of both cemented and cementless modular femoral prostheses in the setting of revision hip arthroplasty. Results of prospective and retrospective studies will be outlined, along with results obtained from national joint registries.
The S-ROM Cementless Femoral Stem: History and Literature Review
Similar to the evolution in cemented techniques, cementless femoral prostheses and procedures have also advanced in order to improve outcomes for patients undergoing revision hip replacement ().- Early results for cementless femoral stems demonstrated high failure rates ranging from 4% to 9.5% within a follow up interval of 1 to 4 years.,, Trousdale and Morrey reported re-revision rates as high as 10%, with 37% showing subsidence of more than 2 mm with a mean average follow up of 4 years. Dorr . showed that with a collared cementless implant the re-revision rate improved from 50% to less than 1% and the subsidence rate was reduced from 50% to 0%. Further improvements were demonstrated by increasing primary stability and modularity of femoral implants. Proximally coated femoral stems, such as the S-ROM modular prosthesis (Joint Medical Products) yielded a 1.5% re-revision rate at 5 year follow-up. Extensively coated modular stems such as the AML prosthesis (DePuy) and the Solution prosthesis (DePuy) had 5.7% and 6% re-revision rates at 8.4 and 5.8 years follow-up, respectively., Wagner presented excellent results for an innovative revision femoral stem. This was a long, fluted, titanium-alloy, and textured stem that relied on diaphyseal fixation. Wagner reported proximal bone ingrowth in relation to the stem. The advent of dual modular femoral implants for revision hip replacement was the next advance in design. Excellent results have been reported by a number of authors, however there are no Level I studies amongst these publications. Gross . presented their results for the ZMR® porous stem (Zimmer, Warsaw, IN, USA) with midterm follow up from 5 to 10 years. This was a prospective study (Level IV evidence) of 72 femoral revisions using this stem only. The survival rate for the prosthesis was 93.8%, with revision for any reason as the endpoint. Mean follow up was 85 months. Holt published their results using the Restoration modular femoral stem (Stryker) in revision hip replacement. This was a prospective cohort study (Level IV evidence) of 46 patients showing a survival rate of 94%. This was a small study with a mean follow up of only 42 months. Cameron . conducted a prospective study with 211 dual modular long stems. Mean follow up was 7 years. The revision rate was 1.4% in this group for aseptic loosening. Garbuz retrospectively reviewed patients who underwent femoral revision between January 2000 and March 2006, comparing dual modular fluted tapered titanium stems with cylindrical non-modular chrome stems. This was a Level III study, which showed that the dual modular group had better outcome scores, fewer complications and better femoral bone preservation or enhancement. However, survival analysis was not performed in this study.
Palumbo . presented their intermediate results using the Stryker Restoration Cone Conical stem in cases with more severe femoral bone loss (Paprosky IIIB and IV). They achieved a 94% success rate with a mean follow up of 4.5 years. Jibodh . recently presented 10-year results using the ZMR stem for femoral revision surgery. This is the longest follow-up period of any published study thus far. The 10-year survival rate, with revision for any reason and revision for femoral loosening as endpoints, were 94% and 100%, respectively. Bolognesi . has presented the only prospective randomized controlled trial using modular femoral stems, comparing hydroxyapatite coating with porous coating using the S-ROM stem. The survival rate for the implant was 94% at 4 years with hydroxyapatite-coated stems fairing significantly better in Paprosky III femora. There have been several complications associated with the use of the dual modular stems in revision hip replacement surgery. Richards reported the incidence of fractures occurring at the diaphyseal/metaphyseal junction of these modular stems. This was attributed to older designs, smaller stems and high body mass index. Sporer ., reported a case of dissociation of a modular femoral neck trunnion. Atwood . presented a case of corrosion-induced fracture of a dual modular stem. Skendzel . reported on similar fractures that were attributed to long varus necks/titanium alloy couplings in modular stems used in patients with high body mass index. This has led to the adoption of cobalt chrome alloy adapters in some stem designs.
Short-Term Results of the S-ROM-A Femoral Prosthesis, …
From January 1999 to December 2004, 65 patients (77 hips) underwent THA due to osteonecrosis of the femoral head using a cementless modular stem design with alumina-on-alumina or metal-on-metal articulation at author's hospital. Eight patients (10 hips) were lost to follow-up and nine patients (nine hips) died within 10 years after the index operation (). Thus, the remaining 48 patients (58 hips) were followed for an average of 12.1 years (range: 10–15 years). There were 26 men and 22 women with a mean age of 51.4 years (range: 23–69 years) at the index arthroplasty. The mean weight was 63.8 kg (range: 43–83 kg), the mean height was 164 cm (range: 148–179 cm), and the mean body mass index was 23.7 kg/m2 (range: 19.2–32.3 kg/m2). The mean preoperative Harris hip score was 39 (range: 11–64) points ().
Read "Short-Term Results of the S-ROM-A Femoral Prosthesis, ..
Holt et al. have described 3 methods of femoral stem revision: i) femoral cement in cement revision with a stable cement bone interface, ii) femoral cement in cement for periprosthetic femoral fractures, and iii) cemented femoral revision with impaction bone grafting. The first method preserves the clinically and radiologically stable cement mantle by removing the old stem and cementing in a new Exeter stem. Duncan et al. quoted a survival rate of 92% for the cement in cement revision with a stable bone cement interface. The second method relates to periprosthetic fractures with two scenarios. In the first scenario, both the stem and the cement mantle are unstable. Both are removed and replaced. In the second scenario, the cement mantle is deemed as stable and preserved with insertion of a new stem after reducing the periprosthetic fracture. This scenario is restricted to a limited number of cases or sometimes performed in the more unfit patients. The third method involves dealing with poor bone stock or bone loss through the use of impaction bone grafting. Halliday et al. reported a survivorship of 90.5% in the impaction bone grafting group. Wraighte et al. have replicated this with a 10-year survivorship of 92%. Ornstein et al. published the results of the Swedish hip registry. The paper looked at the results of 1305 revisions performed between 1989 and 2002 specifically looking at femoral impaction bone grafting. The results showed a 94% survivorship at 15 years follow up. All these established publications clearly highlight the success rate of cemented revision femoral stems and sets the standard with which the newer dual modular cementless femoral stems are evaluated.