Quantitative and individualized assessment of the learning curve using LC-CUSUM.

BACKGROUND: Current methods available for assessing the learning curve, such as a predefined number of procedures or direct observation by a tutor, are unsatisfactory. A new tool, the cumulative summation test for learning curve (LC-CUSUM), has been developed that allows quantitative and individual assessment of the learning curve. METHODS: Some 532 endoscopic retrograde cholangiopancreatographies (ERCPs) performed by one endoscopist over 8 years were analysed retrospectively using LC-CUSUM to assess the learning curve. The procedure was new to the endoscopist and monitored prospectively in the initial study. Success of the procedure was defined as cannulation and proper visualization of the duct(s) selected before the examination. RESULTS: Fifty ERCPs were considered unsuccessful. There was a gradual improvement in performance over time from a success rate of 82.0 per cent for the first 100 procedures to 96.1 per cent for the last 129 procedures. The LC-CUSUM signalled at the 79th procedure, indicating that sufficient evidence had accumulated to prove that the endoscopist was competent. CONCLUSION: LC-CUSUM allows quantitative monitoring of individual performance during the learning process.

Embedding of bone samples in methylmethacrylate: a suitable method for tracking LacZ mesenchymal stem cells in skeletal tissues.

Considerable research has been focused on the use of bone marrow-derived mesenchymal stem cells (MSCs) for the repair of non-unions and bone defects. To date, the question of whether transplanted MSCs survive and engraft within newly formed tissue remains unresolved. The development of an easy and reliable method that would allow cell fate monitoring in transplant recipients is a pressing concern for the field of tissue engineering. To demonstrate the presence of transplanted cells in newly formed bone, we established a xenograft nude rat model allowing the detection of murine LacZ MSCs in vivo. MSCs were isolated from transgenic lacZ mice, seeded onto bioabsorbable collagen sponges, and transplanted to repair a calvarial defect in nude rats. As a preliminary step, the histological procedure was adapted to optimize the detection of LacZ cells in bone tissue embedded in methylmethacrylate (MMA). Four fixatives and four fixation times were evaluated. Among all the fixatives tested, 2% formaldehyde/0.2% glutaraldehyde at 4C for 4 days gave the best results for X-gal staining at pH 7.4 on both cell cultures and bone explants. All fixatives were effective for immunodetection of beta-gal. In the chimeric LacZ/nude rat animal model, MSCs were detected in vivo for up to 4 weeks after implantation and contributed to the repair and the neovascularization of the bone defect. LacZ is a suitable phenotypic marker to track MSCs in skeletal tissues embedded in MMA.

Radiologic assessment of lumbar intervertebral instability and degenerative spondylolisthesis.

Despite many efforts, there is no clear and widely accepted definition of lumbar instability because there are no unquestionable and currently applicable clinical or radiologic criteria available for this entity. This article reviews the current concepts of lumbar instability and the different imaging modalities used to make the diagnosis as evident as possible.

Nerve grafting for traction injuries of the common peroneal nerve. A report of 17 cases.

We report 17 patients who had grafting of the common peroneal nerve after traction injuries. Sixteen were reviewed at a median follow-up of 36 months. The nerve gap ranged from 7 to 20 cm. A functionally satisfactory result was achieved in six patients (37.5%), a fair result in six and a poor result in four. Seven patients had, in addition, a posterior tibialis tendon transfer; this improved the result in five. Grafting produced some satisfactory results even when the nerve gap was as long as 20 cm.

[Osteoconductive properties of bioactive glasses in a bulk form and as a coating on alumina]. / Evaluation du caractère ostéoconducteur de verres bioactifs sous forme massive et en revêtement sur de l'alumine.

INTRODUCTION: Alumina on alumina friction couple has proven its reliability in the field of total hip arthroplasty. However, loosening of the alumina socket has been responsible for most of the failures. An improvement of the bone/alumina interface could be achieved with the use of an osteconductive material as a coating on alumina. The aim of this study was to evaluate the osteconductive properties of two types of bioactive glasses as a coating on alumina substrates. MATERIALS AND METHODS: Two types of coated implants (silicate glass coated alumina - AVSi, and phosphate glass coated alumina - AVP) were evaluated in a rabbit cancellous bone model. Pure alumina implants (A) were used as negative controls and bulk glasses (silicate - VSi and original 45S5, and phosphate glasses -VP) as negative controls. Sacrifices were performed at 3, 12 and 24 weeks. The interface evaluation included histomorphometry using an image analyzer. RESULTS: Silicate glasses demonstrated high osteoconductive properties. However, non mineralized osteoid tissue was the main tissue in contact with both coated implants and bulk phosphate glasses. This tissue covered over 70 p. 100 after 24 weeks of implantation, while it was never observed around pure alumina implants after 3 weeks. DISCUSSION: Amongst the hypotheses that could explain this mineralization inhibitory process, the one involving an Al(3+) glasses contamination from Al(2) O(3) is the likeliest. The high temperature coating procedure could be responsible for alumina transformation into a more soluble phase.

[Cementless acetabular fixation with solid alumina sockets. Apropos of 62 total hybrid prostheses with press-fit alumina sockets at 6-year mean follow-up]. / Fixation acétabulaire non cimentée de cupules en alumine massive. A propos de 62 prothèses totales hybrides à frottement alumine/alumine au recul moyen de 6 ans.

PURPOSE OF THE STUDY: In order to avoid polyethylene wear observed in total hip replacement, an alumina-alumina combination has been used since 1977. The aim of this prospective study was to assess the results of an alumina-alumina total hip arthroplasty with a cementless press-fit plain alumina socket and a cemented titanium alloy stem with special attention for socket fixation because of previously encountered problems. MATERIALS AND METHODS: Fifty-five patients (62 hips) were operated on between 1982 and 1990. The main parameter for inclusion was a high level activity demand. The bearing surfaces were a 32 mm alumina head articulating within the alumina socket. Mean follow-up was 6 years. RESULTS: Four revisions occurred in this series: 3 for aseptic loosenings of the socket and 1 for femoral head fracture. Considering acetabular revision for aseptic loosening as the end point, the survival rate was 93.2 % at six years and 78.8 % at six years when considering acetabular loosening as the end point. At a mean of 72.1 month-follow-up, 92.4 % of the remaining hips were graded as very good or good while 44.6 % showed radiolucent lines around the socket and 4 had migrated with no radio-clinical correlation. On the femoral side, there was no radiolucent line nor loosening, and the value of the colar calcar resorption was low (mean 0.4 mm). In all four revisions, the stem was left in place, and there was no bone loss, which allowed simple revisions. DISCUSSION: Thin radiolucent lines around bulk alumina press-fit sockets can be understood as a normal bone reaction to material as the Young's modulus is much higher. They do not necessarily signify mechanical failure of the fixation. However when considering the rate of acetabular loosening, an improvement of the alumina/bone interface is still required.

[Bilateral diaphyseal hyperostosis of the leg bones in adults. Apropos of a case]. / Hyperostose diaphysaire bilatérale des os de la jambe de l'adulte. A propos d'un cas.

A new case of bilateral, diaphyseal hyperostosis of the leg bones is reported. Strictly unilateral symptoms appeared when the patient was 35 years old consisting of unbearable pain in the middle section of the antero-medial side of the left leg. Diagnosis was based on X-rays and a pre-operative bone scintiscan, showing localised hyperfixation opposite the pain site. Preoperative locating using a radioactive marker enabled circumscribed but complete excision of the hyperfixation site. This diagnosis was confirmed by the pathologist examination. The patient, who experienced immediate relief after surgery, has remained pain-free for one year to date. The relationship between this case and Camurati-Engelmann disease (diaphyseal dysplasia) is discussed.

A lateral approach to the distal humerus following identification of the cutaneous branches of the radial nerve.

We describe a lateral approach to the distal humerus based on initial location of the superficial branches of the radial nerve, the inferior lateral cutaneous nerve of the arm and the posterior cutaneous nerve of the forearm. In 18 upper limbs the superficial branches of the radial nerve were located in the subcutaneous tissue between the triceps and brachioradialis muscles and dissected proximally to their origin from the radial nerve, exposing the shaft of the humerus. The inferior lateral cutaneous nerve of the arm arose from the radial nerve at the lower part of the spiral groove, at a mean of 14.2 cm proximal to the lateral epicondyle. The posterior cutaneous nerve of the forearm arose from the inferior lateral cutaneous nerve at a mean of 6.9 cm (6.0 to 8.1) proximal to the lateral epicondyle and descended vertically along the dorsal aspect of the forearm. The size and constant site of emergence between the triceps and brachioradialis muscles constitute a readily identifiable landmark to explore the radial nerve and expose the humeral shaft.

A meta-analysis of patellar replacement in total knee arthroplasty.

From individual randomized studies it is unclear whether the patella should be replaced during total knee replacement. We did a meta-analysis to provide quantitative data to compare patellar resurfacing with nonresurfacing during total knee arthroplasty. Only randomized, controlled trials reported between January 1966 and August 2003 comparing patellar replacement with patella retention were included for a total of 12 studies. Two reviewers assessed trial quality and extracted data from papers. The outcomes identified were reoperations for patellar problems, anterior knee pain, knee scores, stair climbing, and patient satisfaction. The resurfaced patella performed better, and we found an increased relative risk (defined by the ratio of the risk of the event in the resurfaced group on the risk of the event in the nonresurfaced group) for reoperation, for significant anterior knee pain, and for significant pain during stair climbing when the patella was left unresurfaced. No differences were observed between the two groups for International Knee Society function score, Hospital for Special Surgery score, and for patient satisfaction. Despite these general findings, forming a definitive conclusion is difficult because many confounding factors, such as component design, surgeon experience, and technical aspects of the surgery, might influence the result in a patient.

Alumina-alumina hip replacement in patients younger than 50 years old.

From April 1977 to December 1990, 131 total hip arthroplasties were performed on 113 patients younger than 50 years of age (median, 41 years); 64 were men and 49 women. The majority were active people. Sixty-six hips had no previous operations, and 33 had at least one previous arthroplasty. The femoral component was a cemented collared titanium alloy stem, and alumina socket was cemented for 99 hips and press-fit for 32. The mean follow-up period was five years, with 32 hips followed for more than ten years. Revision arthroplasty was considered as a failure. Survivorship analysis depicted a 97.5% rate of survival at five years, an 89.4% rate at ten years, and an 86.2% at 11 years. Nine revisions were performed: one experienced a femoral head rupture after three years, one had bipolar loosening, one experienced femoral cystic formation, and six were revised for acetabular cup loosening, all from the cemented group. Two revisions occurred on the same patient. No stem revision was necessary before ten years. Only one of these revisions was required in patients aged 40 or younger (64 patients). Alumina-alumina friction is an extremely interesting phenomenon in young patients, and could be related to the low wear debris production.

Total knee replacement after failed tibial osteotomy: results of a matched-pair study.

Sixty-three total knee replacements were performed after a failed tibial osteotomy. The goal of this study was to compare the perioperative problems and the outcome of this group of patients (study group) to a group of patients with primary arthroplasties matched for age, gender, length of follow-up, weight, and preoperative Charnley class. Operative problems were more frequently encountered in the study group, with 7 tibial tubercle elevations and 15 lateral retinaculum releases needed, whereas lateral retinaculum release was necessary for only 1 knee in the control group. Outcome was assessed using both the International Knee Society (IKS) scoring system and Hospital for Special Surgery (HSS) knee score. The follow-up period averaged 4.6 years. The IKS score of the control group was significantly higher, averaging 80.9 +/- 13.8, whereas it was 74.4 +/- 14.8 for the study group (P = .0001). Among the parameters included in the knee score, only pain was significantly different with the control group (P = .03). The IKS function score and the HSS score were not statistically different. Conversion of a failed tibial osteotomy is a technically demanding procedure. Careful preoperative planning is needed. Results, especially on pain, appeared to be inferior to those for primary arthroplasties.

Cementless bulk alumina socket: preliminary results at 6 years.

To avoid polyethylene wear observed in total hip replacement, an alumina-alumina combination has been used since 1977. The aim of this study is to report the results of a hybrid alumina-alumina total hip arthroplasty with a cementless press-fit bulk alumina socket and a cemented titanium alloy stem in 55 patients (62 hips) operated on between 1982 and 1990. The bearing surfaces were a 32-mm alumina head articulating within the alumina socket. Four failures occurred: 3 aseptic loosenings of the socket and 1 femoral head fracture. Considering aseptic loosening as the endpoint, the survival rate was 93.2% after 6 years. At a mean of 72.1 months' follow-up, 92.4% of the surviving hips were graded as very good or good using the Merle d'Aubigné-Postel hip score. Radiolucent lines were observed on the acetabular side in 68.1 of the hips. The future of this interface, which is probably fibrous, remains questionable. With the exception of 1 femoral head fracture, all revisions were related to failure of the bony fixation of the socket, and no problem was encountered related to the alumina-alumina friction coupling. Alumina sockets with other types of cementless fixation have therefore been designed and are presently under clinical investigation.

Ten-year survivorship of cemented ceramic-ceramic total hip prosthesis.

In the first 187 consecutive alumina-alumina combination hip arthroplasties performed from 1977 to 1979, both components were cemented with conventional techniques. At ten-year follow-up evaluation, 87 patients were reviewed or interviewed by telephone, 37 were dead, 39 were lost to follow-up evaluation, and 24 failures were reoperated on before the end of ten years. The major cause of failure was aseptic loosening of the acetabular component (15 failures). Fracture of the socket and of the femoral head occurred in five patients in this series. However, these complications were not seen with components manufactured after 1979. At the end of ten years, survivorship analysis depicted a 82.59% survival rate when reoperation was considered as failure and a 88.57% rate when reoperation for aseptic loosening was considered as failure. The femoral component had a 99.16% survival rate and the acetabular component had an 88.57% survival rate when reoperation for aseptic loosening was considered as failure. Age, appearance of a two- or three-zone demarcation at the intermediate follow-up evaluation, and outer diameter of the acetabular component were the major parameters influencing the results. Better results observed in the population younger than 50 years of age may be related to the small amount of wear debris produced by the alumina-alumina combination. This combination in hip prosthesis is secure, but should be implanted in young and active patients; the outer diameter of the acetabular component must be at least 50 mm. The major problem that remains is the socket's fixation. It could be improved by a design modification, by choosing another mode of fixation, or both.