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Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_XXXVII | Pages 21 - 21
1 Sep 2012
Pospischill R Weninger J Pokorny A Altenhuber J Ganger R Grill F
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Background

Several risk factors for the development of osteonecrosis following treatment of developmental dislocated hip have been reported. The need for further research with a large-enough sample size including statistical adjustment of confounders was demanded. The purpose of the present study was to find reliable predictors of osteonecrosis in patients managed for developmental dislocation of the hip.

Methods

A retrospective cohort study of children, who have been hospitalized at our department between January 1998 and February 2007 with a developmental dislocation of the hip, was completed. Sixty-four patients satisfied the criteria for inclusion. Three groups according to age and treatment were identified. Group A and B included patients treated with closed or open reductions aged less than twelve months. Patients of group C were past walking age at the time of reduction and were treated by open reduction combined with concomitant pelvic and femoral osteotomies. The average duration of follow-up for all patients was 6.8 years. Logistic regression analysis was conducted to identify predictors for the development of osteonecrosis.


Orthopaedic Proceedings
Vol. 93-B, Issue SUPP_IV | Pages 429 - 430
1 Nov 2011
Knahr K Pokorny A Frank A
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Background: Recently, the new phenomenon of “squeaking” noises emitted from THAs with ceramic-onceramic bearings has spared international interest. It shows a frequency of 0,7–19,5% in literature, but infrequently requires revision surgery. However, an even higher incidence of various other noises from those THAs audible to the human ear have become popular in the process: this noise can resemble clicking, grinding or creaking and can be caused by distinct movements, during longer periods of walking, or can be constant with movement. The incidence of those noises can reach up to 30% of THAs. However, memory has faded that other bearings like metal-on-metal and PE/ceramic have been associated with noises in the past.

Therefore we aimed to investigate the occurence of acoustic emissions in patients, who had all received the same implant but with alternate bearings, to investigate the nature of noise, duration and clinical consequence for all 3 bearings (polyethylene/ceramic, metalon-metal, ceramic-on-ceramic).

Method: Between 1999–2001, 360 patients were matched in a prospective randomised trial. All of them received a cementless Zimmer© Alloclassic Variall™ implant at the Orthopaedic Hospital Vienna – Speising, Austria with either a ceramic-on-ceramic bearing, a metal-on-metal bearing or a polyethylene/ceramic bearing. A questionnaire was sent via mail, including questions on first occurence of hip noise, information on the kind and duration of the phenomenon and possible adverse evaluation on behalf of the patient. In case of a positive report, the patient was invited to a clinical examination and radiographic analysis. In addition, a specialised audiography was conducted in patients with audible sensations. Finally, the SF-36 and WOMAC were analysed. A number of patients received further examination with methods of gait analysis in order to detect the distinct point of occurence of the noise during the gait cycle.

Results: 33 patients reported an audible phenomenon from their THA, 14 received a ceramic-onceramic bearing (Cerasul), 13 a polyethylene/ceramic bearing (Durasul) and 6 a metal-onmetal bearing (Metasul). The most common noise was a distinct clicking, followed by a creaking noise. Only 1 patient reported a squeaking sensation, he received a polyethylene/ceramic bearing.

Conclusion: The emission of specific noises from THAs of all bearings has been well documented in recent trials and could be verified in this survey of cementless THAs. No trend towards an increased incidence of noise from THAs with ceramic-on-ceramic bearings could be detected. Interestingly, the single case of „squeaking” was reported from a patient with polyethylene/ceramic bearing. Microseparation and subluxation of the femoral head with resulting edge loading and formation of stripe wear has recently been suspected as the main cause for “noisy hips.” So far 2 ceramic-on-ceramic hips of this study group population have been revised. Both articulations showed areas of stripe wear due to subluxation of the joint.


Orthopaedic Proceedings
Vol. 92-B, Issue SUPP_IV | Pages 528 - 528
1 Oct 2010
Pospischill M Knahr K Pokorny A
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Aims: The aim of this study is to present long-term results of the cementless Alloclassic total hip arthroplasty system of up to 21 years.

Matarial and Methods: 152 consecutive primary hip arthroplasties using a threaded conical titanium cup (Alloclassic CSF) and a rectangular titanium press-fit stem (Alloclassic SL) were implanted between September 1987 and December 1988. In all cases a 32 mm alumina ceramic head and a UHMW polyethylene inlay were used. Clinical and radiological results were available for 55 patients (36,2%) with a minimum of 15 years (15.0 to 20.9 years). Clinical results were evaluated according to the Harris Hip Score, the SF-36 and WOMAC score. Radiographic results were analysed on anteroposterior x-rays according to the method of DeLee and Charnley for the cup and of Gruen for the stem.

Results: The average Harris Hip Score at the last follow-up was 87.3. The mean pain score was 41.5, the mean functional score 47.3. Radiographic results showed osteolytic lesions around the cup in one case. Radiolucent lines around the stem were observed only in the proximal zones in 2/3 of the cases, cortical hyperthrophy occurred in the distal zones in ¾ of the evaluated hips.

23 hips (15.1%) needed revision surgery. The majority (17 hips – 73.9% of all reoperations) were revised due to progressive Polyethylene wear, all after a minimum of ten years. Exchange of the polyethylene inlay and the ceramic head was performed in 14 hips. In two cases the acetabular component and in one case the femoral component were found to be loose intraoperatively because of the wear debris and had to be exchanged. 4 hips had to be revised due to aseptic cup loosening without signs of increased polyethylene wear. There was one revision due to a late deep infection and one because of a periprothetic femoral fracture.

Conclusion: Our data suggest that excellent long-term results can be achieved with the cementless Alloclassic system. The main limiting factor for implant survival was found in increased polyethylene wear. We therefore recommend early exchange of the inlay to avoid loosening and the use of modern wear couples such as ceramic-on-ceramic, metal-on-metal or crosslinked polyethylene.