1.
Eighty-six Percent Failure Rate of a Modular-Neck Femoral Stem Design at 3 to 5 Years: Lessons Learned.
Bernstein, DT, Meftah, M, Paranilam, J, Incavo, SJ
The Journal of bone and joint surgery. American volume. 2016;(12):e49
Abstract
BACKGROUND While innovation drives advancement, it is not immune to failure. Previously, we reported a corrosion-related revision rate of 28% (23 of 81 total hip arthroplasties) among patients who received the Rejuvenate modular-neck stem implant with short-term follow-up. Because we observed a dramatic interval failure rate after our initial report, we undertook this study. METHODS We prospectively followed a cohort of patients who had undergone implantation of the Rejuvenate modular-neck stem, as previously reported. At a minimum of 3 years of follow-up (range, 3.0 to 5.5 years), 73 hips in 63 patients (90% of the original group) were available for analysis. The mean serum cobalt and chromium ion levels were obtained preoperatively and postoperatively. Elevated serum cobalt ion levels (>4 μg/L), pain, or abnormal magnetic resonance imaging (MRI) findings were indications for revision surgery. Patient factors and serum metal ion levels were correlated to revision surgery. Additionally, post-revision serum cobalt and chromium ion level trends were assessed. RESULTS An 86% clinical failure rate (63 of the 73 hips) was observed at a mean follow-up of 4.2 ± 0.6 years (range, 3.0 to 5.5 years); 57 (78%) of the hips underwent revision at a mean of 3.2 ± 1.0 years (range, 1.0 to 5.5 years), and 6 (8%) of the hips were scheduled for revision. Patients who underwent revision surgery were younger and had greater serum metal ion levels and greater pain compared with patients who did not undergo revision. An elevated serum cobalt ion level was the most important independent factor associated with revision surgery. Cobalt ion levels decreased sharply after revision; however, some patients demonstrated persistent elevation with more gradual decline. CONCLUSIONS Emphasizing the reporting of positive results may leave orthopaedic surgeons reticent to publicize negative results; however, the high failure rate of this implant design within 5 years prompted this report. We believe that patients and orthopaedic surgeons should be made aware of this implant's clinical problems and patients should be followed closely. Expedient revision is necessary when failure is identified, to minimize potentially severe tissue damage and metal toxicity. LEVEL OF EVIDENCE Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.
2.
Diagnosis and Treatment of Adverse Local Tissue Reactions at the Head-Neck Junction.
Cooper, HJ
The Journal of arthroplasty. 2016;(7):1381-4
Abstract
Modular junctions in total hip arthroplasty are susceptible to mechanically assisted crevice corrosion, leading to the release of metal wear debris. Adverse local tissue reactions result from an immune-mediated biological reaction to this debris and can have a profound effect on the surrounding periarticular soft tissue envelope. Patients often present with pain or muscle weakness and demonstrate elevated serum cobalt and chromium levels. Serum inflammatory markers and synovial fluid tests help distinguish these reactions from deep infection in the majority of cases; however, the presence of amorphous material or fragmented cells can lead to difficulty in some cases. Advanced cross-sectional imaging is essential in establishing the diagnosis. Early revision surgery is generally the treatment of choice for symptomatic adverse local tissue reaction from corrosion at the modular head-neck junction. The existing stem is retained, and a new ceramic head is placed on the existing trunnion whenever possible. This strategy generally leads to short-term improvement of symptoms with reliable clinical outcomes; however, longer term results are presently lacking.
3.
Effects of metal-on-metal wear on the host immune system and infection in hip arthroplasty.
Hosman, AH, van der Mei, HC, Bulstra, SK, Busscher, HJ, Neut, D
Acta orthopaedica. 2010;(5):526-34
Abstract
BACKGROUND AND PURPOSE Joint replacement with metal-on-metal (MOM) bearings have gained popularity in the last decades in young and active patients. However, the possible effects of MOM wear debris and its corrosion products are still the subject of debate. Alongside the potential disadvantages such as toxicity, the influences of metal particles and metal ions on infection risk are unclear. METHODS We reviewed the available literature on the influence of degradation products of MOM bearings in total hip arthroplasties on infection risk. RESULTS Wear products were found to influence the risk of infection by hampering the immune system, by inhibiting or accelerating bacterial growth, and by a possible antibiotic resistance and heavy metal co-selection mechanism. INTERPRETATION Whether or not the combined effects of MOM wear products make MOM bearings less or more prone to infection requires investigation in the near future.
4.
[Heparin induced thrombocytopenia. A frequently unrecognised complication after major orthopedic surgery].
Picker, SM, Gathof, BS
Der Orthopade. 2004;(11):1300-8
Abstract
The application of unfractioned (UFH) and low molecular weight heparins (LMH) has reduced the incidence of thromboembolic events. However, the frequency of heparin-induced thrombocytopenia (HIT II) in orthopedic patients, particularly susceptible for both thromboembolic complications and HIT II with potentially life threatening complications, is about 0.5% for LMW and 3% UFH. Induced by an immune response, the excessive activation of platelets and endothelial cells causes massive thrombin generation and, as a result, thrombotic vessel occlusion. The rates of mortality and amputation in HIT II are estimated to be 30% and 20%, respectively. The clinical course is highly dependent on early therapeutic intervention, consisting of compatible and adequately dosed anticoagulation drugs. Vitamin K antagonists as well as platelet substitution may lead to disastrous sequelae. We summarize the current state of the pathophysiology, diagnosis and therapy of HIT II and illustrate therapeutic mistakes in a case report.