G. Kern

Primary total hip arthroplasty revision due to dislocation: Prospective French multicenter study

INTRODUCTION Dislocation following total hip arthroplasty (THA) may require surgical revision, and is one of the most frequent causes for revision in national registers. The goals of this study were to determine the characteristics of revision THA for dislocation and identify the typical features of hips revised due to dislocation. MATERIALS AND METHODS A prospective multicenter study (30 centers) was performed in first revision THA performed between January 1, 2010 and December 31, 2011 (multiple revisions were excluded). RESULTS Two hundred nineteen (10.4%) of all first revisions (2153 cases in 2107 patients) were for dislocation, which was the fifth cause of revision. There were 135 men and 84 women, mean age 65.9 years old (24.3-92.4) at primary THA and 72.9 years old (31.9-98.8) at revision. Revision surgery was performed a mean 7.1 years (± 7.1) after primary THA. The predictive risk factors for dislocation were: a 22.2mm diameter femoral head (risk × 2.4), a posterolateral approach (risk × 1.7), older age (risk × 1.1), an elevated rim liner for primary THA (risk × 6.6). The use of a dual mobility cup did not influence the rate of revision for dislocation (8.8%) compared to the use of a flat rim liner (9.1%). DISCUSSION The 10.4% rate of revision of THA for dislocation seems markedly lower than the results in the literature both for frequency and ranking. The use of elevated rim or constrained liners designed to decrease the risk of dislocation does not improve results compared to standard liners. LEVEL OF EVIDENCE Level IV, prospective prognostic study without a control group.

Knee arthrodesis using a customised modular intramedullary nail in failed infected total knee arthroplasty.

BACKGROUND Knee arthrodesis is used to treat patients with failed infected total knee arthroplasty (TKA). Among fixation methods, intramedullary nailing increases the chances of bone union but may carry a risk of infection around the nail. This risk is not well understood, because available case-series studies were not confined to patients with knee infection. HYPOTHESIS Infection recurrence rates after knee arthrodesis with intramedullary nailing used to treat failed infected TKA are similar to those seen with other fixation methods. METHODS We retrospectively reviewed 31 cases of knee arthrodesis with fixation by a modular intramedullary nail performed at a subspecialized center treating complex osteoarticular infections (CRIOAC). The antibiotic regimen was determined based on multidisciplinary discussions and microbiological studies of preoperative and intraoperative specimens. Mean follow-up was 50 ± 22 months (range, 28-90 months). Arthrodesis was performed in one stage (n=6) or two stages (n=25). Success was defined as presence, after a postoperative follow-up of at least 24 months, based on the following criteria: normal erythrocyte sedimentation rate and/or C-reactive protein, no wound inflammation or sinus tract, no revision surgery, and no antibiotic treatment. Bone union was not a criterion for a successful arthrodesis procedure. RESULTS Removal of the fixation material was required in three patients and long-term palliative antibiotic therapy in three patients (fixation material in place with repeated positive specimens) for a total of six failures due to infection (6/31, 19.4%). None of the patients experienced mechanical failure (no breakage of the material and no fixation failure of the nails designed to allow osteointegration). The mean leg length discrepancy was 10 ± 10 mm (range, 5-34 mm) and the mean Oxford score was 41 ± 11 (range, 23-58). The 50-month rate of arthrodesis survival to revision surgery for nail removal was 77.8 ± 4% and the 50-month rate of arthrodesis survival without revision surgery for persistent infection was 74.6 ± 4.2%. DISCUSSION The infection recurrence rate was higher than with other fixation methods but remained acceptable (19.4%). Use of a modular intramedullary nail prevented major leg-length discrepancies, which are often poorly accepted by the patients, and allowed immediate weight bearing despite the often severe bone loss. LEVEL OF EVIDENCE Level IV, retrospective cohort study.

Head Size and Metal-on-Metal Bearings

The reintroduction of metal-on-metal (M-M) bearing components in total hip arthroplasty (THA) occurred with small-diameter heads (28–32 mm) in the late 1980s and gave excellent results up to 15 years of follow-up (Dastane et al. 2011; Grubl et al. 2007; Migaud et al. 2011). Shortly thereafter, M-M hip resurfacing (SRA) resurged, and favorable outcomes are currently reported at follow-up exceeding 12 years (Amstutz et al. 2010; Coulter et al. 2012; Treacy et al. 2011). From this rapid overview of the literature on metallic articulations, one may erroneously conclude that bearing diameter has no influence on survival of M-M articulations. Currently, there is growing controversy regarding M-M bearings considering adverse reactions to metallic debris (ARMD) and concerns about blood ion elevation (Engh et al. 2010; Glyn-Jones et al. 2009; Hart et al. 2012; Heneghan et al. 2012). In fact, these side effects were rare at the time small M-M bearings were reintroduced: Rising metallic ion levels in blood were low (Grubl et al. 2007), and aseptic lymphocytic vasculitis-associated lesions (ALVAL) were extremely uncommon (<1/15,000) with small M-M (Willert et al. 2005) while pseudotumors were marginal (1/100,000) (Gruber et al. 2007). Looking back, controversy mainly emerged after large M-M bearings were launched in the late 1990s, particularly after the introduction of large-diameter head (LDH) THA and after dissemination of SRA (Heneghan et al. 2012). The goal of this chapter is to assess if these concerns apply equally to different diameters of M-M articulations.