ABSTRACT
We present a series of 35 patients (19 men and 16 women) with a mean age of 64 years (36.7 to 75.9), who underwent total hip replacement using the ESKA dual-modular short stem with metal on-polyethylene bearing surfaces. This implant has a modular neck section in addition to the modular head. Of these patients, three presented with increasing post-operative pain due to pseudotumour formation that resulted from corrosion at the modular neck-stem junction. These patients underwent further surgery and aseptic lymphocytic vaculitis associated lesions were demonstrated on histological analysis. Retrieval analysis of two modular necks showed corrosion at the neck-stem taper. Blood cobalt and chromium levels were measured at a mean of nine months (3 to 28) following surgery. These were compared with the levels in seven control patients (three men and four women) with a mean age of 53.4 years (32.1 to 64.1), who had an identical prosthesis and articulation but with a prosthesis that had no modularity at neck-stem junction. The mean blood levels of cobalt in the study group were raised at 50.75 nmol/l (5 to 145) compared with 5.6 nmol/l (2 to 13) in control patients. Corrosion at neck-stem tapers has been identified as an important source of metal ion release and pseudotumour formation requiring revision surgery. Finite element modelling of the dual modular stem demonstrated high stresses at the modular stem-neck junction. Dual modular cobalt-chrome hip prostheses should be used with caution due to these concerns.
Subject(s)
Arthroplasty, Replacement, Hip/adverse effects , Chromium/blood , Cobalt/blood , Granuloma, Plasma Cell/etiology , Hip Prosthesis/adverse effects , Adult , Aged , Arthroplasty, Replacement, Hip/methods , Corrosion , Female , Finite Element Analysis , Humans , Male , Middle Aged , Pain, Postoperative/etiology , Prosthesis Design , Prosthesis Failure , Reoperation , Stress, MechanicalABSTRACT
Injuries related to weight training are becoming increasingly common as the trend for body resistance training grows. There have been numerous injuries related to repeated stress, but this appears to be the first reported case of a fracture of the shaft of clavicle related to violent muscular contraction. It occurred in a 28 year old man during bench pressing. He was treated conservatively and the fracture united in six weeks. Resistant trainers should be made aware of the risks of heavy weight training and need proper supervision.
