Outcomes using wedge stem with full hydroxiapatite coverage with a minimum of 5 years' follow-up

Catastrophic Early Failure and Fragmentation of a Modern Moderately Cross-linked Polyethylene Acetabular Liner

A 60-year-old man who underwent uncomplicated staged bilateral total hip arthroplasty for femoral head osteonecrosis presented with mechanical catching of his left total hip arthroplasty 3 years after index surgery. Radiographs revealed eccentricity of the left femoral head, concerning the failure of a modern moderately cross-linked polyethylene liner. Catastrophic polyethylene liner failure with significant wear, fragmentation, and femoral head abrasion was noted during revision surgery. The original liner and head were replaced, and the patient has exhibited no complications, pain, or difficulty ambulating 6 months postoperatively. This report highlights one potential novel mechanism for the failure of the Exactech Connexion GXL liner (Exactech Inc., Gainesville, FL), an implant recently reported to have a higher-than-expected failure rate, potentially due to insufficient packaging and increased oxidative processes.

Primary total hip arthroplasty with a fully porous-coated uncemented stem: up to twenty-eight years. Retrospective cohort study

PURPOSE

The use of cementless prosthesis has increased in the last 30 years with the aim of improving the long-term results of total hip arthroplasties in young and active patients. Encouraging results have recently been reported for cementless titanium and cobalt chromium stems. However, there are few studies with long-term follow-up, and the majority have analysed several models of uncemented stems due to their modifications over the years. Therefore, the aim was to assess the long-term survival rate of the Mittelmeier Mark III or Autophor 900-S stem.

METHODS

A retrospective cohort study of both gender patients under 70 years old with at least one implanted Mittelmeier Mark III uncemented stem was performed. Survival rate was defined as the proportion of stems that did not need a surgical revision from any cause. Clinical status was evaluated using the Merle d'Aubigne scale modified by Matta (excellent/good/fair/poor).

RESULTS

Between 1990 and 1999, 73 stems were implanted. The mean (SD) age at surgical time was 49.3 (9.9) years, and the median (range) of follow-up was 22 (1-28) years. The overall survival rate was 93% (68/73, 95%CI: 85-97%). The stem revisions were due to stem breakage (n = 2), to aseptic loosening (n = 2) and to septic loosening (n = 1). Clinical results were: excellent 84%, good 15% and fair 1.5%.

CONCLUSIONS

The Mittelmeier Mark III stem had an excellent survival rate with a stable long-term fixation and excellent clinical outcomes.

Nanosized hydroxyapatite and β-tricalcium phosphate composite: Physico-chemical, cytotoxicity, morphological properties and in vivo trial

The objective of this work was to characterize the properties of a synthetic biomaterial composite with nanoparticles size (Blue Bone). This biomaterial is a composite recommended for dental and orthopedic grafting surgery, for guided bone regeneration, including maxillary sinus lift, fresh alveolus filling, and treatment of furcation lesions. The nano biomaterials surface area is from 30% to 50% higher than those with micro dimensions. Another advantage is that the alloplastic biomaterial has homogeneous properties due to the complete manufacturing control. The analyzed biomaterial composite was characterized by XRD, cytochemistry, scanning electron microscopy, porosimetry and in vivo experiments (animals). The results showed that the analyzed biomaterial composite has 78.76% hydroxyapatite [Ca₅(PO₄)₃(OH)] with monoclinic structure, 21.03% β-tricalcium phosphate [β -Ca₃(PO₄)₂] with trigonal structure and 0.19% of CaO with cubic structure, nanoparticles with homogeneous shapes, and nanoporosity. The in vivo experiments showed that the composite has null cytotoxicity, and the site of insertion biomaterials has a high level of vascularization and bone formation. The conclusion is that the synthetic biomaterial with Blue Bone designation presents characteristics suitable for use in grafting surgery applications.