Biomedical subjects

Pascal Boileau

Publications and source records attributed to Pascal Boileau.

31 records · Page 2Linked to original sources

PubMed2002

Decreased glibenclamide uptake in hepatocytes of hepatocyte nuclear factor-1alpha-deficient mice: a mechanism for hypersensitivity to sulfonylurea therapy in patients with maturity-onset diabetes of the young, type 3 (MODY3).

Diabetes in subjects with hepatocyte nuclear factor (HNF)-1alpha gene mutations (maturity-onset diabetes of the young [MODY]-3) is characterized by impaired insulin secretion. Surprisingly, MODY3 patients exhibit hypersensitivity to the hypoglycemic actions of sulfonylurea therapy. To study the pharmacogenetic mechanism(s), we have investigated glibenclamide-induced insulin secretion, glibenclamide clearance from the blood, and glibenclamide metabolism in wild-type and Hnf-1alpha-deficient mice. We show that despite a profound defect in glucose-stimulated insulin secretion, diabetic Hnf-1alpha(-/-) mice have a robust glibenclamide-induced insulin secretory response. We demonstrate that the half-life (t(1/2)) of glibenclamide in the blood is increased in Hnf-1alpha(-/-) mice compared with wild-type littermates (3.9 +/- 1.3 vs. 1.5 +/- 1.8 min, P <or= 0.05). The clearance of glibenclamide from the blood during the first hours after intravenous administration was reduced approximately fourfold in Hnf-1alpha(-/-) mice compared with Hnf-1alpha(+/+) littermates. Glibenclamide uptake into hepatocytes was dramatically decreased in vivo and in vitro. To study the metabolism of glibenclamide in Hnf-1alpha(-/-) animals, we analyzed liver extracts from [(3)H]glibenclamide-injected animals by reverse-phase chromatography. We found that the ratio of the concentrations of glibenclamide and its metabolites was moderately increased in livers of Hnf-1alpha(-/-) mice, suggesting that hepatic glibenclamide metabolism was not impaired in animals with Hnf-1alpha deficiency. Our data demonstrate that high serum glibenclamide concentrations and an increased t(1/2) of glibenclamide in the blood of Hnf-1alpha(-/-) mice are caused by a defect in hepatic uptake of glibenclamide. This suggests that hypersensitivity to sulfonylureas in MODY3 patients may be due to impaired hepatic clearance and elevated plasma concentrations of the drug.

Animals↗

PubMedDate not supplied

Burst fracture of the spine involving vertebrae presenting no other lesions: the role of vertebroplasty.

We report our experience on percutaneous vertebroplasty performed on five patients who presented with history of trauma to the spine and secondary burst fracture, but with stable fractures, and on whom the medical and orthopedical therapies had been unsuccessful in the relief of the intractable pain and in the treatment of their functional status. Four cases have benefitted from the intervention, with complete disappearance of the symptomatology in two and incomplete in the other two. In one case, the improvement in the persistent painful symptoms was of no significance. Controls by computed tomography (CT). Which were performed after 3 months showed a satisfactory consolidation of the fractured vertebrae.

Adult↗

PubMedDate not supplied

Shoulder arthroplasty in patients with osteoarthritis and dysplastic glenoid morphology.

Fifteen shoulders with primary osteoarthritis and dysplastic glenoid morphology underwent shoulder arthroplasty (eleven total shoulder arthroplasties and four hemiarthroplasties). Patients were evaluated at a mean of 37 months after replacement with clinical examination, Constant score, subjective patient opinion, and radiographic examination. One glenoid component was loose, necessitating removal; the remainder of the prostheses were in place at latest follow-up. Significant improvement was observed in Constant score (32 points preoperatively vs 71 points postoperatively) and active mobility (anterior elevation, 89 degrees preoperatively vs 146 degrees postoperatively; external rotation, 7 degrees preoperatively vs 45 degrees postoperatively) after arthroplasty. This study demonstrates that the rare scenario of osteoarthritis coupled with a dysplastic glenoid can be treated successfully with shoulder arthroplasty.

Aged↗

PubMedDate not supplied

Entrapment of the long head of the biceps tendon: the hourglass biceps--a cause of pain and locking of the shoulder.

We describe an unrecognized mechanical condition affecting the long head of the biceps (LHB) tendon with entrapment of the tendon within the joint and subsequent pain and locking of the shoulder on elevation of the arm. We identified 21 patients with a hypertrophic intraarticular portion of the LHB tendon during open surgery (14 patients) or arthroscopic surgery (7 patients). All cases but one were associated with a rotator cuff rupture. Patients were treated by biceps tenotomy (2 patients) or tenodesis (19 patients) after removal of the hypertrophic intraarticular portion of the tendon and appropriate treatment of concomitant lesions. Minimum follow-up was 1 year. All patients presented with anterior shoulder pain and loss of active and passive elevation averaging 10 degrees to 20 degrees. A dynamic intraoperative test, involving forward elevation with the elbow extended, demonstrated entrapment of the tendon within the joint in each case. This test creates a characteristic buckling of the tendon and squeezing of it between the humeral head and the glenoid (hourglass test). The mean Constant score improved from 38 to 76 points at the final follow-up (P <.05). Complete and symmetric elevation was restored in all cases after resection of the intraarticular portion of the LHB tendon. The hourglass biceps is caused by a hypertrophic intraarticular portion of the tendon that is unable to slide into the bicipital groove during elevation of the arm; it can be compared with the condition of trigger finger in the hand. A loss of 10 degrees to 20 degrees of passive elevation, bicipital groove tenderness, and radiographic findings of a hypertrophied tendon can aid in the diagnosis. A definitive diagnosis is made at surgery with the hourglass test: incarceration and squeezing of the tendon within the joint during forward elevation of the arm with the elbow extended. The hourglass biceps is responsible for a mechanical block, which is similar to a locked knee with a bucket-handle meniscal tear. Simple tenotomy cannot resolve this mechanical block. Excision of the intraarticular portion of the LHB tendon, during bipolar biceps tenotomy or tenodesis, must be performed. The hourglass biceps is an addition to the familiar pathologies of the LHB (tenosynovitis, prerupture, rupture, and instability) and should be considered in cases of shoulder pain associated with a loss of elevation.

Aged↗

PubMedDate not supplied

Grammont reverse prosthesis: design, rationale, and biomechanics.

Combined destruction of the rotator cuff and the glenohumeral joint may lead to a painful and pseudo-paralyzed shoulder. In this situation a nonconstrained shoulder prosthesis yields a limited functional result or may even be contraindicated. Previous constrained prostheses (ball-and-socket or reverse ball-and-socket designs) have failed because their center of rotation remained lateral to the scapula, which limited motion and produced excessive torque on the glenoid component, leading to early loosening. The reverse prosthesis designed by Paul Grammont, unlike any previous reverse ball-and-socket design, has introduced 2 major innovations that have led to its success: (1) a large glenoid hemisphere with no neck and (2) a small humeral cup almost horizontally oriented with a nonanatomic inclination of 155 degrees, covering less than half of the glenosphere. This design medializes and stabilizes the center of rotation, minimizes torque on the glenoid component, and helps in recruiting more fibers of the anterior and posterior deltoid to act as abductors. Furthermore, the humerus is lowered relative to the acromion, restoring and even increasing deltoid tension. The Grammont reverse prosthesis imposes a new biomechanical environment for the deltoid muscle to act, thus allowing it to compensate for the deficient rotator cuff muscles. The clinical experience does live up to the biomechanical concept: the reverse prosthesis restores active elevation above 90 degrees in patients with a cuff-deficient shoulder. However, external rotation often remains limited, particularly in patients with an absent or fat-infiltrated teres minor. Internal rotation is also rarely restored after a reverse prosthesis. Failure to restore sufficient tension in the deltoid may result in prosthetic instability. The design does appear to protect against early loosening of the glenoid component, but impingement of the humeral cup on the scapular neck can lead to scapular notching and polyethylene wear. This is a cause for concern, especially as the notch is often more extensive than can be explained by impingement alone. Bony lysis of the scapula may also be related to a polyethylene granuloma. Further follow-up is required to ensure that loosening does not become a problem in the long term, and it has been recommended to limit its use to elderly patients, arguably those aged over 70 years. Despite these concerns, the reverse prosthesis, based on the biomechanical Grammont concept, offers a true surgical option in several situations where only limited possibilities were previously available: cuff tear arthrosis, persistent shoulder pseudo-paralysis due to a massive and irreparable cuff tear, severe fracture sequelae, prosthetic revision in a cuff-deficient shoulder, and tumor surgery. Finally, surgeons must be aware that results are less predictable and complication/revision rates are higher in revision surgery.

Biomechanical Phenomena↗

PubMedDate not supplied

Radiographic comparison of flat-back and convex-back glenoid components in total shoulder arthroplasty.

The purpose of this study was to compare the radiographic results of 2 different glenoid component designs. This series consisted of 66 shoulder arthroplasties with primary osteoarthritis divided into 2 groups based on glenoid component type. One group comprised shoulders receiving cemented flat-back polyethylene glenoid implants. The other group comprised shoulders receiving cemented convex-back polyethylene glenoid implants. Immediate postoperative and 2-year postoperative radiographs were evaluated for the presence and progression of periglenoid radiolucencies, and the 2 groups were compared. Radiolucent line scores were calculated and compared for each group. The keeled, convex-back glenoid component was radiographically better than the keeled, flat-back glenoid component.

Adult↗

PubMedDate not supplied

Bicipital groove orientation: considerations for the retroversion of a prosthesis in fractures of the proximal humerus.

The bicipital groove anatomy is well documented, and this groove is used as a landmark to guide retroversion during implantation of a shoulder prosthesis. Whereas the proximal part of the groove is used in osteoarthritis, the distal part is used in fractures. If used in 4-part fracture cases, we must assume that the bicipital groove orientation is constant from proximal to distal. We measured the groove orientation in 40 cadaveric humeri using 3 superimposed computed tomography sections. The reference axis was the transepicondylar axis at the elbow level. The measured angle of the bicipital groove was 55.8 degrees +/- 4.5 degrees at the anatomic neck and 65.1 degrees +/- 3.5 degrees at the surgical neck. This difference (mean of 9.3 degrees, with extremes of -3 degrees and 22.5 degrees) was statistically significant. We confirmed a wide range of variation from 22 degrees to 89 degrees in the orientation of the groove. Because the values listed in the literature for lateral fin placement of a prosthesis have not been measured at the surgical neck level and because of the great variation in groove orientation, we caution surgeons about the use of the bicipital groove as a reliable landmark in shoulder replacement for fractures. Considering the risk of over- or under-retroversion of the prosthesis, we recommend the use of a fracture jig with retroversion set to 20 degrees.

Arthroplasty, Replacement↗

PubMedDate not supplied

Neer Award 2005: The Grammont reverse shoulder prosthesis: results in cuff tear arthritis, fracture sequelae, and revision arthroplasty.

This clinical study was performed to analyze the midterm results and potential complications of the reverse prosthesis in different diagnosis. Forty-five consecutive patients with Grammont prosthesis were evaluated clinically and radiographically with a mean follow-up of 40 months (range, 24-72 months). The indication was a massive and irreparable cuff tear associated with arthrosis (CTA) in 21 cases, fracture sequelae (FS) with arthritis in 5 cases, and failure of a revision arthroplasty (revision) in 19 cases. Fourteen complications occurred in 11 patients. 3 dislocations, 3 deep infections (all 3 in the revision group), 1 case of aseptic humeral loosening, 2 periprosthetic humeral fractures, 1 intraoperative glenoid fracture, 1 wound hematoma, 2 late acromial fractures, and 1 axillary nerve palsy. Of the patients, 10 (22%) required further surgery: 4 reoperations, 4 prosthesis revisions, and 2 prosthesis removals. Complications were higher in revision than in CTA (47% vs. 5%). All 3 groups showed a significant increase in active elevation (from 55 degrees preoperatively to 121 degrees postoperatively) and Constant score (from 17 to 58 points) but no significant change in active external rotation (from 7 degrees to 11 degrees ) or internal rotation (S1 preoperatively and postoperatively). Of the patients, 78% were satisfied or very satisfied with the result and 67% had no or slight pain. However, the postoperative Constant score, adjusted Constant score, and American Shoulder and Elbow Surgeons shoulder score were all significantly higher in the CTA group with as compared with the revision group (P = .01, .004, and .002, respectively). Scapular notching was seen in 24 cases (68%). No glenoid loosening was observed at current follow-up, even when the notch extended beyond the inferior screw (28% of cases). Atrophy of severe fatty infiltration of the teres minor was associated with lower external rotation (15 degrees vs 0 degrees , P = .02) and lower functional results (Constant score of 46 points vs 66 points, P < .007). The Grammont reverse prosthesis can improve function and restore active elevation in patients with incongruent cuff-deficient shoulders; active rotation is usually unchanged. Results are less predictable and complication and revision rates are higher in patients undergoing revision surgery as compared with those in patients with CTA. Results of the reverse prosthesis depend on the diagnosis and on the remaining cuff muscles, specifically the teres minor. Surgeons should be vigilant with regard to low-grade infection in revision surgery.

Aged↗

PubMedDate not supplied

The TOTS (temporary outside traction suture): a new technique to allow easy suture placement and improve capsular shift in arthroscopic bankart repair.

We describe a new technique to allow easy placement of anterior sutures and to improve the proximal capsular shift in arthroscopic anterior stabilization of the shoulder, which we call the temporary outside traction suture (TOTS). Two standard portals are used: posterior and anterosuperior. Using a curved suture hook, both the capsule and the labrum are perforated at approximately the 5-o'clock position, and a monofilament suture is passed through the tissues. The suture is first retrieved through the anterior canula and then placed outside the canula. After labrum detachment and glenoid preparation, 1 or 2 further inferior sutures can be placed before the first suture is retrieved inside the canula and used. The technique of the TOTS has many advantages. (1) It allows easy placement of the first suture before the anterior capsule and labrum have been released. This makes this step much more difficult due to the lack of tension in the anterior tissues and anterior subluxation of the humeral head. (2) It allows the surgeon to choose, with accuracy, the amount of capsule taken, according to the severity of the capsular lesions and the degree of capsular laxity. It can also allow anatomic recreation of the anterior band of the inferior glenohumeral ligament (IGHL). (3) By placing tension on the suture, it avoids damaging the anterior capsule and labrum with the shaver and burr while preparing the scapula neck and can aid with haemostasis. (4) Tension on the suture also allows one to easily place 1 or 2 further sutures in a lower position. (5) It avoids entangling the sutures in the canula. (6) It allows one to perform a capsular shift of approximately 10 to 15 mm when the traction suture is retrieved and implanted with an anchor in the 3- or even 2-o'clock position.

Arthroscopy↗

PubMedDate not supplied

A comparison of hemiarthroplasty and total shoulder arthroplasty in the treatment of primary glenohumeral osteoarthritis: results of a multicenter study.

Six hundred one total shoulder arthroplasties and eighty-nine hemiarthroplasties were performed for primary osteoarthritis of the shoulder. Patients were evaluated with a physical examination, Constant score, and radiographic evaluation. The minimum follow-up was 2 years. At follow-up, the Constant score averaged 64 points, the adjusted Constant score averaged 86%, active anterior elevation averaged 130 degrees, and active external rotation averaged 36 degrees for the hemiarthroplasties. The Constant score averaged 70 points, the adjusted Constant score averaged 96%, active anterior elevation averaged 145 degrees, and active external rotation averaged 42 degrees for the total shoulder arthroplasties. Eighty-six percent of hemiarthroplasties and ninety-four percent of total shoulder arthroplasties had good or excellent results. Differences were statistically significant for all parameters. Total shoulder arthroplasty provided better scores for pain, mobility, and activity than hemiarthroplasty. Fifty-six percent of total shoulder arthroplasties had a radiolucent line around the glenoid component. Total shoulder arthroplasty provides results superior to those of hemiarthroplasty in primary osteoarthritis.

Adult↗

PubMedDate not supplied

Arthroscopic biceps tenodesis: a new technique using bioabsorbable interference screw fixation.

PURPOSE: To report a new technique of arthroscopic biceps tenodesis using bioabsorbable interference screw fixation and the early results. TYPE OF STUDY: Prospective, nonrandomized study. METHODS TECHNIQUE: The principle of arthroscopic biceps tenodesis is simple: after biceps tenotomy, the tendon is exteriorized and doubled on a suture; the biceps tendon is then pulled into a humeral socket (7 or 8 mm x 25 mm) drilled at the top of the bicipital groove, and fixed using a bioabsorbable interference screw (8 or 9 mm x 25 mm) under arthroscopic control. PATIENTS: 43 patients treated with this technique between 1997 and 1999 were followed-up for at least 1 year. The technique was indicated in 3 clinical situations: (1) with arthroscopic cuff repair (3 cases), (2) in case of isolated pathology of the biceps tendon with an intact cuff (6 cases), and (3) as an alternative to biceps tenotomy in patients with massive, degenerative and irreparable cuff tears (34 cases). The biceps pathology was tenosynovitis (4 cases), prerupture (15 cases), subluxation (11 cases), and luxation (13 cases). RESULTS: The absolute Constant score improved from 43 points preoperatively to 79 points at review (P <.005). There was no loss of elbow movement and biceps strength was 90% of the strength of the other side. Two patients, operated on early in the series, presented with a rupture of the tenodesis. In both cases the bicipital tendon was very friable and the diameter of the screw proved to be insufficient (7 mm). No neurologic or vascular complications occurred. CONCLUSIONS: Arthroscopic biceps tenodesis using bioabsorbable screw fixation is technically possible and gives good clinical results. This technique can be used in cases of isolated pathologic biceps tendon or a cuff tear. A very thin, fragile, almost ruptured biceps tendon is the technical limit of this arthroscopic technique.

Absorbable Implants↗

PubMedDate not supplied

Prosthetic replacement in the treatment of osteoarthritis of the shoulder: early results of 268 cases.

Two hundred sixty-eight anatomically designed shoulder arthroplasties for primary osteoarthritis were reviewed at a mean follow-up of 30 months. The Constant score adjusted for age and sex was 38% preoperatively and 97% at follow-up. Good or excellent results were observed in 77% of patients, and 94% were satisfied or very satisfied. Mean active forward elevation was 145 degree postoperatively, and all clinical parameters improved. Glenoid radiolucent lines were present in 58% of cases and were associated with a less satisfactory objective result. Postoperative active forward elevation, strength, and Constant score were inversely related to a tear of the supraspinatus or fatty degeneration of the infraspinatus. Patients who underwent biceps tenodesis had better pain relief. Complications occurred in 8.6% of cases, and 4.9% of shoulders required reoperation. Good early results can be obtained with nonconstrained shoulder arthroplasty in primary osteoarthritis.

Adult↗

PubMedDate not supplied

Cemented polyethylene versus uncemented metal-backed glenoid components in total shoulder arthroplasty: a prospective, double-blind, randomized study.

Thirty-nine patients (forty shoulders) with primary osteoarthritis consented to be randomized to receive either a cemented all-polyethylene glenoid component or a cementless metal-backed component at the time of total shoulder arthroplasty. Their mean age was 69 years. Preoperative and postoperative evaluations were completed at 3, 6, 12, 24, and 36 months by history, physical examination, radiographs, and Constant scoring system. The presence of periprosthetic radiolucent lines was significantly greater with polyethylene than with metal-backed glenoids (85% vs 25%, P <.01). Of 20 radiolucent lines, 12 (60%) around polyethylene glenoids were present on immediate postoperative radiographs and 25% were progressive. No significant correlation was found between the presence of radiolucent lines around polyethylene glenoids and functional results (P =.3). By contrast, periprosthetic radiolucent lines around metal-backed glenoids were rare but progressive when present. The incidence of loosening of metal-backed implants (4 cases, 20%) was significantly higher than that observed with polyethylene glenoids (0%, P <.001) and was associated with component shift and severe osteolysis. Metal-backed glenoid loosening significantly correlated with deteriorating functional results and increasing pain (P <.05). Revision surgery was required for 4 patients in the metal-backed group (P =.02), for a subscapularis tear (1 case) and metal-backed glenoid component loosening (3 cases). Computed tomography scan analysis and revision surgery revealed that preoperative posterior humeral subluxation may recur with time despite glenoid reorientation and may cause asymmetric accelerated polyethylene wear, resulting in metal-on-metal contact and severe osteolysis. Reimplantation of a stable cemented glenoid component was possible in 1 case, whereas the cavitary defect was packed with cancellous bone in the 2 other cases. At a minimum of 3 years' follow-up, the results of this study clearly show that (1) the survival rate of cementless, metal-backed glenoid components is inferior to cemented all-polyethylene components and (2) the incidence of radiolucency at the glenoid-cement interface with all-polyethylene components is high and remains a concern. The high rate of loosening, because of the absence of ingrowth and/or the accelerated polyethylene wear, has led us to abandon the use of metal-backed glenoids. Efforts must continue to improve glenoid component design and fixation.

Aged↗