The aim of this study was to analyze the frequency and reveal the most common reasons of the endoprosthetic instability in patients with malignant bone tumors. From 1992 – 2008, 625/515 patients, endoprosthetic replacement of major joints were performed. The median age of the patients was 30.3 years (13 to 72 years).

Aseptic instability was observed after 3/71(4.2%) humeral joint replacement out of total operations at this location, after 4/80 (5%) hip prosthesis, after 19/133 (14%) proximal tibial prostheses, after 44/299 (14.7%) distal femoral prostheses and after 2/37 (5.4%) total femur replacements.

The retrospective analyses has shown that the reasons of instability were the following: aseptic loosening of the stems of endoprosthesis in 26 cases (24.4%), stem break in 31 (36.1%), endoprosthetic unit destruction in 10 (11.6%), untwistment of fixational screws in 10 (11,6%), migration of hip endoprosthesis components in 2 (2.3%) and endoprosthesis dislocation in 12 (14%). The timing of endoprosthetic instability ranged from 7 days to 12.2 years (average 26.2 months). Statistic analyses was performed in a group of patients with aseptic endoprosthesis instability developed after proximal tibia and distal femur resection.

We conclude that the most frequent reason of aseptic instability was endoprosthetic stem break. The instability rate was actually lower among the patients who had underwent 5–10cm distal tibia resection comparing with the group of 10–15cm bone mass resection (p=0.05). Femoral resection enhanced the instability frequency comparing with proximal tibia resection in the group of 5–10cm bone mass resection (p=0.05).

From 1992 on 2008, 615/515 patients underwent primary or revisional endoprosthetic replacement of major joints. In 51 patients (31 men & 20 women) modular system MUTARS (Implantcast, Germany) has been used. The median age was 23.3 years (15 to 52 years).

MUTARS modular endoprosthesis has been used in 10 patients with deep infection of endoprosthetic bed as a revisional endoprosthetic replacement: 1 Total endoprosthetic replacement of femur, 5 Total knee joint replacement (2 for distal femoral defect and 3 for proximal tibial defect). In 3(27%) patients, we used newly patented silver ion coated MUTARS either after two stage treatment for infection of endoprosthetic bed or as a prophylaxis of endoprosthetic infection.

In 1 patient (23 yrs), with 12cm limb length shortening, we used extensible MUTARS as a revisional endoprosthetic replacement.

The following complications we observed: Instability of endoprosthesis – 3/51 (5.9%), deep endoprosthetic bed infection – 4/51 (7.8%).

In comparison group, when using custom-made endoprosthesis, the frequency of infectious complications have made 60/574 (10.5 %), and instability of implants was observed in 79/574 (13.8 %) cases.

Transition of using modular systems for primary and revisional endoprosthesis allows to reduce the level of instability from 13.8 % to 5.9 %. The quantity of infectious complications is also not great as in comparison with control group. For revisional endoprosthetic replacement, we think, the given modular system is optimal, for correcting limb length deficiency and restoration of basic function at patients. Use of silver ion coated modular implants is a promising method for treating deep endoprosthetic bed infection.

The incidence of DDH Varies depending on genetic and ethnic varieties but in Ireland on an average in 3 per 1,000 live births. Current treatment is focused on early diagnosis and congruent reduction of the hip joint. With conservative measures, principally skilful use of the Pavlik harness, the majority of (85%) of dislocated or subluxated hips will be successfully treated. Late diagnosis impacts on the mode of treatment and on the subsequent outcome.

An audit of annual incidence of DDH in North Eastern health board, in Ireland showed a dramatic increase in late diagnosis (> 4 month). There were 4668 live births in 2004 with 17 cases of DDH presenting between the ages of 4 – 36 months during this period. The mean age of presentation was 10 months. Two cases were bilateral. The male: female ratio was 4.6:1. Risk factor analysis showed, only 50% fell in to the high risk group, majority of them had positive family history. Three fourth of them were frank dislocations and all of them required operative intervention. As opposed to early presenters, only 10% needed operative intervention. 30% of the late presenters needed major osteotomies.

We examined the reasons for this extreme high rate of late presenters and argue for the introduction of routine ultrasound screening in this region based on historical high incidence of DDH and the dramatic incidence of delayed diagnosis.