Cemented Müller straight stem total hip replacement: 18 year survival, clinical and radiological outcomes.

AIM: To present the 18 year survival and the clinical and radiological outcomes of the Müller straight stem, cemented, total hip arthroplasty (THA). METHODS: Between 1989 and 2007, 176 primary total hip arthroplasties in 164 consecutive patients were performed in our institution by the senior author. All patients received a Müller cemented straight stem and a cemented polyethylene liner. The mean age of the patients was 62 years (45-78). The diagnosis was primary osteoarthritis in 151 hips, dysplasia of the hip in 12 and subcapital fracture of the femur in 13. Following discharge, serial follow-up consisted of clinical evaluation based on the Harris Hip Score and radiological assessment. The survival of the prosthesis using revision for any reason as an end-point was calculated by Kaplan-Meier analysis. RESULTS: Twenty-four (15%) patients died during the follow-up study, 6 (4%) patients were lost, while the remaining 134 patients (141 hips) were followed-up for a mean of 10 years (3-18 years). HSS score at the latest follow-up revealed that 84 hips (59.5%) had excellent results, 30 (22.2%) good, 11 (7.8%) fair and 9 (6.3%) poor. There were 3 acetabular revisions due to aseptic loosening. Six (4.2%) stems were diagnosed as having radiographic definitive loosening; however, only 1 was revised. 30% of the surviving stems showed no radiological changes of radiolucency, while 70% showed some changes. Survival of the prosthesis for any reason was 96% at 10 years and 81% at 18 years. CONCLUSION: The 18 year survival of the Müller straight stem, cemented THA is comparable to those of other successful cemented systems.

Open ankle dislocation without associated malleolar fracture.

Open ankle dislocation without an associated fracture is an extremely rare injury. We present the case of a 24-year-old male athlete who had sprained his left ankle during volleyball playing. He sustained an open posteromedial dislocation of his left ankle, without an associated malleolar fracture. The treatment consisted of wound irrigation, debridement, reduction, and suture of the skin, followed by immobilization with a short leg cast. The ankle was immobilized in a neutral position for 8 weeks, and weight bearing was restricted for the first 6 weeks. At the 3-month follow-up visit, the patient reported that both ankle and feet had regained full, pain-free range of motion. At the 6-month follow-up visit, he returned to sports activities. At 9 months of follow-up, the patient participated in volleyball games at the same level as before his injury. At 2 years after the initial injury, he did not have any clinical complaints, and his ankle had no clinical or subjective signs of instability.

Experimental osteomyelitis caused by methicillin-resistant Staphylococcus aureus treated with a polylactide carrier releasing linezolid.

BACKGROUND: The effectiveness of a new delivery system consisting of polymerized dilactide (PLA) with incorporated linezolid was investigated in a rabbit model as a means of treating methicillin-resistant Staphylococcus aureus (MRSA) osteomyelitis. METHODS: The PLA-linezolid system was prepared after thorough stirring of PLA with linezolid at a 10:1 ratio. Experimental osteomyelitis was established in 40 rabbits by a modification of the Norden model with MRSA as the test isolate. After a hole had been drilled in the upper right femur, the isolate was inoculated using a thin needle working as a foreign body. At three weeks, the needle was removed and cultured, and the PLA-linezolid system was implanted in half the animals (group B); the remaining half was the control group (group A). Animals were sacrificed at regular intervals; tissue around the site of implantation was examined for pathologic changes and cultured quantitatively. RESULTS: The prepared system eluted linezolid in vitro at concentrations much greater than the minimum inhibitory concentration (MIC) of the test pathogen for 11 days. At three weeks after inoculation of the test isolate, all animals had osteomyelitis. By the sixth week, bacterial growth from cancellous bone of group B was significantly lower than that in group A. However, this effect was not maintained until the end of the study (weeks 8 and 10), when the differences in bacterial growth in the two groups were not significant. CONCLUSION: Polymerized dilactide mixed with 10% linezolid achieved partial arrest of the offending pathogen in an experimental model of osteomyelitis caused by MRSA.

Investigation on the distal screw of a trochanteric intramedullary implant (Fi-nail) using a simplified finite element model.

Numerous studies have been published concerning the characteristics and the behaviour of the intramedullary devices in the treatment of the intertrochanteric hip fractures. However, there is still room for further exploration and exploitation concerning the implant behaviour with respect to the parts of the implant assembly (nail, lag screw and distal screw). Towards this direction, the present paper aimed at revealing the effect of the position of the distal screw on the mechanical behaviour of the fixation device. For this purpose, a simplified model was developed and analysed with the finite element method. In total, five different locations for the distal screw were examined. In all cases, the bone was fixed at its distal end while the external load was applied at the tip of the lag screw towards the hip and in the form of orthonormal force components applied individually. The results of the FE analyses were illustrated in appropriately formed plots revealing the sensitivity of the behaviour of the implant with respect to the location of the distal screw. The main conclusion derived from the present investigation was that moving the distal screw apically decreases the stresses on the distal screw but increases the stresses on the lag screw. In turn, this indicates the existence of a location for the distal screw that compromises these two effects in an optimum way.

Recurrent intra-articular osteoid osteoma of the hip after radiofrequency ablation: a case report and review of the literature.

We present a case of a 53-year-old woman with recurrent intra-articular osteoid osteoma of the hip 6 months after initial treatment with percutaneous radiofrequency ablation. En bloc surgical excision of the osteoid osteoma and prophylactic internal fixation for impending stress fracture was performed. The patient is pain free, has returned to normal function and there is no sign of recurrence at the one-year follow-up. Intraarticular osteoid osteoma, present a diagnostic challenge and often they are misdiagnosed. Minimally invasive ablation techniques can fail in significant percentage and then surgical excision with histological confirmation remains the definitive treatment of choice.

Treatment of experimental osteomyelitis by methicillin resistant Staphylococcus aureus with bone cement system releasing grepafloxacin.

The authors examined the effectiveness of the local anti-microbial treatment on methicillin resistant Staphylococcus aureus (MRSA) experimental osteomyelitis. Thirty-six rabbits with chronic MRSA osteomyelitis of the right femur were treated with local grepafloxacin delivery system prepared by a mixture of acrylic bone cement (polymethyl methacrylate, PMMA) plus 4% grepafloxacin. Osteomyelitis was induced by inoculating MRSA (100 microl of cultured bacteria; 10(7)) and the local insertion of a needle, serving as a foreign body, at the upper third of the femur. The course of the infection was followed by clinical, radiographic and microbiological examination. In the third week, all animals were re-operated, needles were removed, and antibiotic containing acrylic cement was implanted. Thereafter, one control and five treated animals were sacrificed per week, within 6 weeks. Osteomyelitis was found in all rabbits. In vitro grepafloxacin levels remained high throughout the 6 weeks of the experiment. Histologically tissue reaction against the cement was not observed. Osteomyelitis lesions and bone structure were progressively repaired after cement implantation. Biomechanical analysis showed no significant influence on the mechanical properties of acrylic cement due to grepafloxacin. The above mixture could prove to be an important supplementary method for the treatment of bone infections. Such a system could replace the use of gentamycin PMMA beads in the treatment of patients with chronic osteomyelitis due to MRSA. Furthermore, the proposed method could be used as a spacer after removal septic loosened prostheses in combination with systemic administration of antibiotics.