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Biomedical subjects

C Gerber

Publications and source records attributed to C Gerber.

At least 55 records · Page 3Linked to original sources
PubMed1999

Radiolucent lines and component stability in knee arthroplasty. Standard versus fluoroscopically-assisted radiographs.

The radiolucent lines and the stability of the components of 66 knee arthroplasties were assessed by six orthopaedic surgeons on conventional anteroposterior and lateral radiographs and on fluoroscopic views which had been taken on the same day. The examiners were blinded as to the patients and clinical results. The interpretation of the radiographs was repeated after five months. On fluoroscopically-assisted radiographs four of the six examiners identified significantly more radiolucent lines for the femoral component (p < 0.05) and one significantly more for the tibial implant. Five examiners rated more femoral components as radiologically loose on fluoroscopically-assisted radiographs (p = 0.0008 to 0.0154), but none did so for the tibial components. The mean intra- and interobserver kappa values were higher for fluoroscopically-assisted radiographs for both components. We have shown that fluoroscopically-assisted radiographs allow more reproducible, and therefore reliable, detection of radiolucent lines in total knee arthroplasty. Assessment of the stability of the components is significantly influenced by the radiological technique used. Conventional radiographs are not adequate for evaluation of the stability of total knee arthroplasty and should be replaced by fluoroscopically-assisted films.

Aged↗
PubMed1999

Experimental rotator cuff repair. A preliminary study.

BACKGROUND: The repair of chronic, massive rotator cuff tears is associated with a high rate of failure. Prospective studies comparing different repair techniques are difficult to design and carry out because of the many factors that influence structural and clinical outcomes. The objective of this study was to develop a suitable animal model for evaluation of the efficacy of different repair techniques for massive rotator cuff tears and to use this model to compare a new repair technique, tested in vitro, with the conventional technique. METHODS: We compared two techniques of rotator cuff repair in vivo using the left shoulders of forty-seven sheep. With the conventional technique, simple stitches were used and both suture ends were passed transosseously and tied over the greater tuberosity of the humerus. With the other technique, the modified Mason-Allen stitch was used and both suture ends were passed transosseously and tied over a cortical-bone-augmentation device. This device consisted of a poly(L/D-lactide) plate that was fifteen millimeters long, ten millimeters wide, and two millimeters thick. Number-3 braided polyester suture material was used in all of the experiments. RESULTS: In pilot studies (without prevention of full weight-bearing), most repairs failed regardless of the technique that was used. The simple stitch always failed by the suture pulling through the tendon or the bone; the suture material did not break or tear. The modified Mason-Allen stitch failed in only two of seventeen shoulders. In ten shoulders, the suture material failed even though the stitches were intact. Thus, we concluded that the modified Mason-Allen stitch is a more secure method of achieving suture purchase in the tendon. In eight of sixteen shoulders, the nonaugmented double transosseous bone-fixation technique failed by the suture pulling through the bone. The cortical-bone-augmentation technique never failed. In definite studies, prevention of full weight-bearing was achieved by fixation of a ten-centimeter-diameter ball under the hoof of the sheep. This led to healing in eight of ten shoulders repaired with the modified Mason-Allen stitch and cortical-bone augmentation. On histological analysis, both the simple-stitch and the modified Mason-Allen technique caused similar degrees of transient localized tissue damage. Mechanical pullout tests of repairs with the new technique showed a failure strength that was approximately 30 percent of that of an intact infraspinatus tendon at six weeks, 52 percent of that of an intact tendon at three months, and 81 percent of that of an intact tendon at six months. CONCLUSIONS: The repair technique with a modified Mason-Allen stitch with number-3 braided polyester suture material and cortical-bone augmentation was superior to the conventional repair technique. Use of the modified Mason-Allen stitch and the cortical-bone-augmentation device transferred the weakest point of the repair to the suture material rather than to the bone or the tendon. Failure to protect the rotator cuff post-operatively was associated with an exceedingly high rate of failure, even if optimum repair technique was used. CLINICAL RELEVANCE: Different techniques for rotator cuff repair substantially influence the rate of failure. A modified Mason-Allen stitch does not cause tendon necrosis, and use of this stitch with cortical-bone augmentation yields a repair that is biologically well tolerated and stronger in vivo than a repair with the conventional technique. Unprotected repairs, however, have an exceedingly high rate of failure even if optimum repair technique is used. Postoperative protection from tension overload, such as with an abduction splint, may be necessary for successful healing of massive rotator cuff tears.

Animals↗
PubMed1999

MR imaging for traumatic tears of the rotator cuff: high prevalence of greater tuberosity fractures and subscapularis tendon tears.

OBJECTIVE: The purpose of this study was to determine whether occult bony injuries or other characteristic MR abnormalities are frequent in patients suspected of having traumatic tears of the rotator cuff. SUBJECTS AND METHODS: MR arthrography of the shoulder was performed in 24 consecutive patients with suspected traumatic tears of the rotator cuff. MR findings were analyzed with regard to abnormalities of the supraspinatus, infraspinatus, and subscapularis tendons; and the humeral head. A comparison group of 24 consecutive patients with symptoms of nontraumatic tears of the rotator cuff was included in the investigation. RESULTS: Radiographically occult fractures of the greater tuberosity were found in nine (38%) of 24 patients with clinically suspected traumatic tears of the rotator cuff (seven of which occurred in patients <40 years old). Nine partial-thickness and five full-thickness supraspinatus tears were found in the trauma group. In the comparison group, the corresponding numbers were 13 and 10, respectively. Seven partial lesions of the cranial border of the subscapularis and six complete subscapularis tears (all six in patients >40 years old) were found in the trauma group (nine and one in the comparison group). CONCLUSION: Occult greater tuberosity fractures and complete subscapularis tears are commonly seen on MR images in patients suspected of having traumatic tears of the rotator cuff. Greater tuberosity fractures should be looked for specifically in patients younger than 40 years, and subscapularis tears should be looked for specifically in patients older than 40 years.

Adult↗
PubMed1998

Patient-controlled interscalene analgesia with ropivacaine after major shoulder surgery: PCIA vs PCA.

We have compared the efficacy of patient-controlled interscalene analgesia (PCIA) using ropivacaine with patient-controlled analgesia (PCA) using nicomorphine in 60 patients (n = 30 in each group), in a prospective, randomized study. In both groups, all patients received interscalene block with 0.75% ropivacaine before induction of anaesthesia. Six hours after interscalene block, patients in group PCIA received continuous infusion of 0.2% ropivacaine at a rate of 5 ml h-1 with a bolus dose of 3 or 4 ml and a lockout time of 20 min; patients in group PCA received continuous infusion of nicomorphine 0.5 mg h-1 and a bolus dose of 2 or 3 mg with a lockout time of 20 min. Control of pain was significantly better from 12 to 48 h after operation (except at 42 h) in group PCIA. Nausea and pruritus occurred significantly more frequently in group PCA. Patient satisfaction was greater in group PCIA. We conclude that the use of 0.2% ropivacaine using PCIA was an efficient way of managing pain after major shoulder surgery and compared favourably with PCA nicomorphine in terms of pain relief, side effects and patient satisfaction.

Adolescent↗
PubMed1998

Quantitative assessment of the muscles of the rotator cuff with magnetic resonance imaging.

RATIONALE AND OBJECTIVES: The purpose of this study was to establish a magnetic resonance (MR) imaging standard for quantification of the muscles of the rotator cuff. METHODS: Parasagittal T1-weighted turbo spin-echo images of the shoulder were obtained in 70 asymptomatic subjects (35 women, 35 men; age range: 21-70 years, mean: 45 years). Standardized cross-sectional areas (rotator cuff muscle areas divided by the area of the supraspinatus fossa) and standardized signal intensities (related to signal intensities of the teres major muscle) were measured and compared with 30 patients with different stages of rotator cuff tears and 10 patients with glenohumeral instability. In addition, a so-called tangent sign was evaluated with the hypothesis that a healthy supraspinatus muscle crosses a line (tangent) drawn through the superior borders of the scapular spine and the superior margin of the coracoid. RESULTS: Cross-sectional areas of the muscles of the rotator cuff were variable in asymptomatic subjects. Cross-sectional areas (but not signal intensities) did discriminate patients with different stages of rotator cuff tears from asymptomatic subjects. The tangent sign was negative in all asymptomatic subjects but positive in four and nine of 10 patients with medium and large rotator cuff tears, respectively. CONCLUSIONS: A method for quantification of the muscles of the rotator cuff using MR imaging is presented. Cross-sectional areas can be used for quantification of the muscles of the rotator cuff. The tangent sign is a useful MR sign for atrophy of the supraspinatus muscle.

Adult↗
PubMed1998

Tendinopathy and rupture of the tendon of the long head of the biceps brachii muscle: evaluation with MR arthrography.

OBJECTIVE: The purpose of this study was to assess the diagnostic role of MR arthrography in patients with tendinopathy or rupture of the long biceps tendon. MATERIALS AND METHODS: MR arthrograms of 42 consecutive patients with arthroscopic or surgical confirmation of diagnosis (16 normal biceps tendons, 19 with tendinopathy, and seven with ruptures) were analyzed independently by two radiologists. Visibility of the biceps tendon, caliber changes, contour irregularities, and signal intensities were assessed separately in the parasagittal and axial planes. In addition, the two radiologists made an overall evaluation of abnormalities of the biceps tendon using both MR imaging planes. RESULTS: The most reliable MR findings for tendinopathy were caliber changes (sensitivity was 59% for observer 1 and 82% for observer 2; specificity was 88% and 64%, respectively) and signal abnormalities (sensitivity, 77% and 88%, respectively; specificity, 75% and 43%, respectively) in the parasagittal plane. Absence of visualization of the tendon in the parasagittal plane was a reliable sign for rupture (sensitivity, 86% and 86%, respectively; specificity, 94% and 87%, respectively). The overall sensitivity for detecting abnormalities (tendinopathy or rupture) was 92% for observer 1 and 89% for observer 2. Specificity was 56% and 81%, respectively. CONCLUSION: MR findings of tendinopathy and rupture of the biceps tendon are subtle. However, the combination of several MR criteria in two imaging planes makes a reasonably accurate diagnosis possible. The biceps tendon should not only be assessed in the bicipital sulcus on axial images but also on parasagittal images.

Adult↗
PubMed1998

[Clinical examination of the shoulder].

The clinical examination is decisive in the diagnosis of shoulder pathologies. This examination should be exact and systematic and in relation with the anatomical structures. With patient history, the clinical examination allows in over 90% of the cases a correct diagnosis. Complementary exams such as standard X-rays, CT-Scan, MRI and neurological examinations serve to confirm the diagnosis and to allow precise surgical planning.

Diagnostic Imaging↗
PubMed1998

[Classification and therapy of the unstable shoulder].

Instability of the shoulder can be classified as uni- or multidirectional with or without general hyperlaxity. Instability of a shoulder without hyperlaxity is often caused by a single traumatic event for the unidirectional instability and by two or several different events for the rarer multidirectional instability. The diagnosis of unidirectional instability is made with a positive apprehension test. For multidirectional instabilities, the anterior and posterior apprehension tests are positive. The treatment consists of surgical repair of the labrum-capsule complex for both the uni- and the multidirectional instabilities without hyperlaxity. For shoulders with a concomitant hyperlaxity, uni- or multidirectional instability is often caused by only minor trauma. Hyperlaxity itself is not a disease but represents a risk factor of instability. The typical feature of hyperlaxity is the positive "sulcus sign". Unidirectional instability with hyperlaxity is characterised by a positive apprehension test combined with a positive sulcus sign. Multidirectionally unstable shoulders with hyperlaxity have a positive anterior and posterior apprehension test as well as a positive sulcus sign. The unidirectional instability with hyperlaxity is best treated surgically whereas conservative treatment is recommended for the multidirectional instability with hyperlaxity. The voluntary instability without loss of control of position of the shoulder is not a real instability and has an excellent prognosis without treatment.

Chronic Disease↗
PubMed1997

Evidence for the activation of myeloperoxidase by f-Meth-Leu-Phe prior to its release from neutrophil granulocytes.

Activity and release of myeloperoxidase (MPO) was measured in heparinized whole blood samples after activation of neutrophil granulocytes by the chemoattractant N-formyl-methionyl-leucyl-phenylalanine (fMLP) using two different methods: (i) by determination of the amount of MPO released into the blood plasma using a MPO enzyme-immunoassay, and (ii) simultaneously, by measuring the remaining activity within the neutrophils by flow cytometry using the Bayer Technicon H3. Although a part of MPO was released immediately after addition of fMLP, remaining MPO activity within the neutrophils surprisingly increased during the first minutes after incubation. Subsequently, MPO activity dropped due to a continuous release of MPO. In addition to fMLP, granulocyte-macrophage colony stimulating factor (GM-CSF) enhanced MPO activity in neutrophils. These results indicate that MPO is present in resting granulocytes in an inactive or only partially active form and is activated by fMLP and GM-CSF.

Adult↗
PubMed1997

Tendon transfers for the treatment of irreparable rotator cuff defects.

Certain defects of the rotator cuff musculotendinous units cannot be repaired. If restoration of strength is an important treatment goal, then tendon transfers must be considered for palliation. In this article, the anatomical and physiological bases for tendon transfers are discussed, and currently known results with this form of treatment are reviewed.

Humans↗
PubMed1997

Patient-controlled analgesia after major shoulder surgery: patient-controlled interscalene analgesia versus patient-controlled analgesia.

BACKGROUND: The authors compared patient-controlled interscalene analgesia (PCIA) with local anesthetics with intravenous patient-controlled analgesia (PCA) with opioids to manage postoperative pain after major shoulder surgery. METHODS: Forty patients scheduled for elective major shoulder surgery were prospectively randomized to receive either PCIA or PCA. Before surgery, all patients had an interscalene block. In the PCIA group, a catheter was introduced within the interscalene sheath. Six hours after the initial block, patients received for 48 h either a continuous infusion of 0.15% bupivacaine through the interscalene catheter at a rate of 5 ml/h plus a bolus of 3 or 4 ml with a lock-time of 20 min (group PCLA) or a continuous intravenous infusion of nicomorphine at a rate of 0.5 mg/h plus a bolus of 2 or 3 mg with a lock-time of 20 min (group PCA). Pain relief was regularly assessed using a visual analog scale, side effects were noted, and the patients were asked to rate their satisfaction at the end of the study. RESULTS: Pain relief was significantly better controlled in the PCIA group at t = 12 and 18 h (P < 0.05). Vomiting and pruritus were 0 versus 25% and 0 versus 25% for the PCIA and PCA groups, respectively (P < 0.05). Patient satisfaction was greater in the PCIA group (P < 0.05). Time of first bolus administration and paracetamol supplement were similar in both groups. CONCLUSIONS: The use of the PCIA technique was uncomplicated and provided better pain relief than PCA during the first 18 h after operation. The incidence of side effects such as vomiting and pruritus was significantly decreased with the use of PCIA, and patient satisfaction was superior in the PCIA group.

Analgesia, Patient-Controlled↗
PubMed1996

[Assessment of shoulder pain in athletes].

The shoulder joint, the most movable joint in our body, is exposed to a considerable load during many sporting activities. The shoulder can be injured and limited in its function not only by direct and indirect trauma but also by repetitive load. Sports with body contact may cause bruises, glenohumeral and acromio-clavicular dislocations or strains of the rotator cuff. Any repetitive microtrauma, particularly those involving sporting activities requiring repetitive overhead use of the arm, may develop lesions of tendons, glenohumeral instabilities or impingement of the deep surface of the supraspinatus tendon on the posterosuperior glenoid rim and may be frequently the cause of shoulder pain in athletes. After an introduction to the anatomy of the shoulder and an illustration of the biomechanics of throwing, we explain shoulder pains in the athlete caused by tendon lesions, joint instability and by neurovascular shoulder problems with the typical patient history, the clinical signs, physical and imaging studies in detail. Among the typical lesion of tendons we are describing the impingement syndrome of the supraspinatus tendon, the lesions of the biceps tendon and the impingement of the lower surface of the cuff on the postero-superior glenoid labrum. As glenohumeral instability we describe the anterior, posterior, and inferior instability and the multidirectional instability as well. As neurovascular shoulder problems we describe anatomy, function, patient history, etiology, clinical signs, physical examination, differential diagnosis, therapy, and prognosis of lesions of the nervi suprascapularis, axillaris, thoracicus longus, musculocutaneus, and accessorius as well as lesions of the plexus brachialis and in the thoracic outlet syndrome.

Acromioclavicular Joint↗