Highly crosslinked polyethylene does not reduce the wear in total knee arthroplasty: in vivo study of particles in synovial fluid.

The aim was to assess if the reduction in polyethylene wear with highly crosslinked polyethylene suggested by studies with knee simulators is confirmed in patients with a knee arthroplasty. The use of a conventional or a highly crosslinked polyethylene was randomly assigned intraoperatively. Twelve months after surgery a knee arthrocentesis was performed and the synovial fluid of 17 patients in each group was studied analysing the number, size and shape of the polyethylene particles by scanning electron microscope. We found no significant differences in the concentration, size or morphology of polyethylene particles between groups. The great variability in the number of particles between individuals suggests that in vivo polyethylene wear depends on many factors and probably the type of polyethylene is not the most significant.

Polyethylene particles in joint fluid and osteolysis in revision total knee arthroplasty.

BACKGROUND: One of the most frequent reasons for total knee arthroplasty late failure is osteolysis. It has been related to foreign body reaction to polyethylene particles. The aim of this study is to analyse the number, size and morphology of polyethylene particles in synovial fluid in total knee arthroplasty revision and correlate them to the pathology and the degree of osteolysis. METHODS: Synovial fluid was obtained in 12 patients before the revision total knee arthroplasty. Polyethylene particles were isolated and analysed through scanning electron microscopy. Samples of synovial tissue were analysed with optical microscopy while considering the parameters of particles and histiocytic infiltration. Osteolysis was analysed with plain radiography and the macroscopic aspect during surgery. RESULTS: The statistical analysis showed a significant correlation between a high concentration of polyethylene particles in synovial fluid and a high degree of osteolysis. The concentration of particles in synovial fluid also showed a significant correlation with a high degree of particles and histiocytes in the histological analysis. There was a relationship between the size of particles and the degree of osteolysis. No relationship was found between the shape of the particles and the histological findings or the degree of osteolysis. CONCLUSIONS: In an "in vivo" TKA scenario, the presence of a high concentration of polyethylene particles in the synovial fluid seems to be the cause of a highly active foreign body histological reaction, with an increased number of histiocytes, which seems to be the cause of a significant degree of osteolysis around the implant.

Distal Clavicle Osteolysis after Modified Weaver-Dunn's Procedure for Chronic Acromioclavicular Dislocation: A Case Report and Review of Complications.

Distal clavicle osteolysis after acromioclavicular joint stabilization has only been described after the use of hardware for clavicle stabilization or synthetic graft causing a foreign body reaction. This paper reports a very rare case of distal clavicle osteolysis after modified Weaver-Dunn procedure for the treatment of chronic acromioclavicular joint dislocation. The paper also provides a comprehensive review of complications of this surgical technique and discusses a potential vascular etiology and preventive strategies aimed at avoiding clavicle osteolysis.

Symptomatic vertebral artery stenosis secondary to cervical spondylolisthesis.

STUDY DESIGN: Case report. OBJECTIVE: To present a rare case of vertebrobasilar insufficiency (VBI) syndrome secondary to the C6 level isthmic spondylolisthesis. SUMMARY OF BACKGROUND DATA: VBI associated with voluntary head movements is known as the bow hunter syndrome. It may manifest in temporary symptoms of dizziness, syncope, nausea, or motor and sensory deficits in certain head positions. The present syndrome is rare and difficult to diagnose. The authors describe a VBI case caused by vertebral artery compression due to the C6 level isthmic spondylolisthesis (to date, the authors have not found any other similar case described in the literature). METHODS: The patient was a 27-year-old male with a 12-month history of vertigo and dizziness in relation to head movements. These problems interfered with his day-to-day activities.With other causes of neurological and cardiac origin dismissed, the patient was sent for an orthopedic evaluation.Radiological imaging showed spondylolisys, spondylolisthesis, and spina bifida between the facets of the C6 and C7. Dynamic radiographies evidenced C6 and C7 cervical instability.Angio-MRI indicated an anomalous trajectory of the right vertebral artery at the C6 level upon entering the foramen transversarium. However, there were no signs of stenosis. Dynamic angiography confirmed partial stenosis of the right vertebral artery upon rightward head rotation. The substantial suspicion of positional VBI after rejecting other diagnoses and the significant disability of the patient led to treating the patient with anterior cervical arthrodesis at the C6-C7 level. RESULTS: The patient was symptom free for more than 15 months' monitoring and returned to all his daily work and life activities. CONCLUSION: Isthmic spondylolisthesis must be considered as a cause within VBI. Surgery presents good results.