Mid-term result of ceramic bearings in total hip arthroplasty

Purpose

The purpose of this study was to evaluate our clinical experience with ceramic-on-ceramic cementless total hip arthroplasty (THA) and complications after an average follow-up of more than eight years.

Methods

From January 2001 to December 2008, 540 THA with ceramic-on-ceramic bearings were performed in 448 patients (92 bilateral, 54 of which were operated simultaneously) with a mean age 49.9 years (range 18–84) by a senior surgeon. Pre-operative aetiological reasons were developmental dysplasia of the hip (DDH) in 205 hips, degenerative arthritis in 157 hips, avascular necrosis in 51 hips, rheumatoid diseases in 40 hips, posttraumatic arthritis in 40 hips, other reasons in 25 hips and revision surgery in 22 hips. Patients were evaluated with Harris hip score (HSS), and radiological findings of acetabular and femoral component loosening or osteolysis with ceramic bearing related complications like squeaking, liner and head fractures were recorded.

Result

The average duration of follow-up time was 8.2 years (range, five to 13.2). The main Harris hip score increased from 42.4 points preoperatively to 94.9 points at the time of last follow-up. We had one fracture of the ceramic head, 11 clicking and four squeaking; one of them was revised because of terrible squeaking due to acetabular liner fracture, the other three were seldom audible from the outside and followed conservatively. We did not observed loosening or osteolysis due to ceramic bearings at the time of the final follow-up.

Conclusion

Our study has demonstrated that ceramic-on-ceramic bearings can be used safely in different etiological problems. Incidences of noisy hips are becoming less frequent.     

Reduction of implant RF heating through modification of transmit coil electric field

In this work, we demonstrate the possibility to modify the electric‐field distribution of a radio frequency (RF) coil to generate electric field‐free zones in the body without significantly altering the transmit sensitivity. Because implant heating is directly related to the electric‐field distribution, implant‐friendly RF transmit coils can be obtained by this approach. We propose a linear birdcage transmit coil with a zero electric‐field plane as an example of such implant‐friendly coils. When the zero electric‐field plane coincides with the implant position, implant heating is reduced, as we demonstrated by the phantom experiments. By feeding RF pulses with identical phases and shapes but different amplitudes to the two orthogonal ports of the coil, the position of the zero electric‐field plane can also be adjusted. Although implant heating is reduced with this method, a linear birdcage coil results in a whole‐volume average specific absorption rate that is twice that of a quadrature birdcage coil. To solve this issue, we propose alternative methods to design implant‐friendly RF coils with optimized electromagnetic fields and reduced whole‐volume average specific absorption rate. With these methods, the transmit field was modified to reduce RF heating of implants and obtain uniform transmit sensitivity . Magn Reson Med, 2011. © 2010 Wiley‐Liss, Inc.     

Patella infera or patellar tendon adherence after high tibial osteotomy

Purpose

Alterations in patellar height after high tibial osteotomy are found in many instances. Fibrosis of the tendon is implicated as the cause of the mechanism of patella lowering. This study aimed to determine the relationship between the position of the patella and the histopathological findings at the patellar tendon after high tibial osteotomy.

Methods

Nineteen knees in seventeen patients who were consecutively hospitalised for implant extraction are studied. All of the patients had previously undergone closing wedge osteotomy by the same surgeon at the same department. The median follow-up time is 15 months (range: 11–35). Five patients who all underwent high tibial osteotomy at the same time are also included in the study as a control group for histopathological evaluation. All of the patients are evaluated radiologically, patellar tendon biopsies are taken during the operation, and histopathological analyses are performed.

Results

The shortening of the patellar tendon is statistically significant (P < 0.05). The severity of the vascularisation, inflammation, and fibrotic change observed at the distal part of the tendon is evident. However, there is no statistically significant correlation between these findings and the degree of shortening.

Conclusions

The shortening of the tendon occurs as a result of adherence in the distal part of the tendon. It would appear that it is this shortening that causes the difficulties encountered during arthroplasty surgery of osteotomy patients, and not patella infera.

Level of evidence

Retrospective study, Level II.     

Involvement in teaching improves learning in medical students: a randomized cross-over study

Background  

Peer-assisted learning has many purported benefits including preparing students as educators, improving communication skills and reducing faculty teaching burden. But comparatively little is known about the effects of teaching on learning outcomes of peer educators in medical education.     

The effects of cyclosporine on antioxidant enzyme activities and malondialdehyde levels in rabbit hepatic tissues

Possible molecular mechanisms leading to cyclosporine-induced hepatotoxicity has not been cleared yet. Therefore, investigation of antioxidant status of hepatic tissues exposed to cyclosporine A (CsA) and of free radical involvement in the CsA-induced hepatotoxicity seems of importance. For this aim, 20 rabbits were used in the study. In each group (control, CsA, CsA plus vitamin and, vitamin only) there were 5 animals. CsA was given orally (25 mg/kg/day) for 10 days. Vitamins E (100 mg/kg/ day) and C (200 mg/kg/day) combination was injected intramuscularly. After 10th day, animals were killed, and livers were prepared for the enzymatic assays. Activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and catalase (CAT) and, malondialdehyde (MDA) levels were determined in the supernatant fractions. Lowered SOD, unchanged GSH-Px and, increased CAT activities and MDA levels were detected in hepatic tissues of rabbits treated with CsA as compared with controls. In the CsA plus vitamin group, SOD activity was found to be higher, GSH-Px and CAT activities unchanged and MDA levels lower than the CsA group. In the vitamin-treated group, all of the enzyme activities were higher than the controls but MDA levels were unchanged. Correlation analysis revealed some significant differences between the groups. Results suggest that cyclosporine impairs the antioxidant defense system and thus, leads to oxidant stress and peroxidation in rabbit hepatic tissues. It has been established that this process can be prevented by antioxidant vitamin supplementation.     

Significant risk of a second melanoma in patients with a history of melanoma but no further predisposing factors

It is a well-accepted fact that melanoma patients are prone to develop further melanomas. In a cohort of 535 melanoma patients, we determined the incidence of second melanomas, as well as risk factors known to be associated with melanoma development. A retrospective analysis of patients regularly consulting our melanoma care unit revealed second or even further melanomas in 5.6% (n = 30). When compared to the overall population, melanoma patients have at least a 30-fold increased risk for the development of a second melanoma. Twenty of these 30 patients revealed none of the known predisposing conditions for multiple melanomas.     

Possible anatomic structures causing entrapment neuropathies of the median nerve: an anatomic study

This study aimed at identifying the anatomic structures which may be responsible for entrapment neuropathies of the median nerve. Thirty upper extremities of 15 formalin fixed adult cadavers were dissected from the axilla to the distal forearm under Zeiss Opmi 9--FC microscope. We encountered seven different anatomic structures that may compress the median nerve. These structures are the brachialis muscle, Struther's ligament, the bicipital aponeurosis, pronator teres, flexor digitorum superficialis, the accessory head of plexor pollicis longus (Gantzer's muscle) and vascular structures. The supracondylar process, which we did not encounter in our dissection, has been reported as another cause. Based on our dissection findings and on literature, the median nerve can be compressed by seven different structures from the axilla to the distal forearm. Knowledge of the course of the median nerve and its relations with the adjacent anatomic structures facilitates determination of the exact cause of entrapment and allows for a safe surgery.     

To use MIBI or not to use MIBI? That is the question when assessing tumour cells

^99mTc-sestamibi (MIBI) is a well-known tumour imaging agent. Its retention within tumour cell mitochondria is related to perfusion and to the magnitude of the electrical gradient, reflecting cell viability. Several internal cell factors modulate this uptake; for example, multidrug resistance membrane proteins (Pgp and MRP1) and anti-apoptotic BCl-2 protein of the outer mitochondrial membrane can limit retention of MIBI. At the early stage of cell apoptosis, the electrical driving forces of MIBI uptake are impaired, and influx and accumulation are reduced. It seems clear that MIBI can be used before treatment to detect drug resistance, assess anti-apoptotic status and predict treatment efficacy. Although it has been suggested that MIBI might be used to monitor tumour response to treatment, MIBI is unable to differentiate tumours with ongoing apoptosis from those developing drug resistance.     

Spontaneous small bowel perforations due to intestinal tuberculosis should not be repaired by simple closure

Intestinal tuberculosis is a major problem in many regions of the world. The incidence of it is rising in Western countries due to immigration from Third World countries and human immunodeficiency virus infection. The difference between the simple closure and resection and anastomosis was evaluated in this study. Retrospectively, 12 patients with intestinal tuberculosis diagnosed histopathologically among 50 patients with free intestinal perforations operated on between 1995 and 2003 at Turgut Ozal Medical Center were evaluated. Each patient underwent routine laboratory tests and radiologic studies. The most common symptoms of patients were abdominal pain, night sweats, and weight loss. Sites of perforation were ileum in 10 patients (multiple perforation in 4) and jejunum in 2 patients (both had multiple perforations). The perforation was closed by primary closure in 7 patients. Resection-anastomosis was performed in 5 patients. Leaks occurred in overall 3 of 7 patients with primary closure. Three of the 7 patients with leaks due to septicemia died. The mortality rate among all patients was 25%. Intestinal tuberculosis should be kept in mind as a cause in free intestinal perforations. Because of high mortality rate, the resection of the affected area and anastomosis may be the treatment of choice rather than primary closure.