Biomedical subjects

Christian Gerber

Publications and source records attributed to Christian Gerber.

40 records · Page 3Linked to original sources

PubMedDate not supplied

Measurement of glenoid version: conventional radiographs versus computed tomography scans.

Glenoid version seems to play an important role in the stability and loading of the glenohumeral joint. The purpose of this study was to compare measurements of glenoid version on axillary views and computed tomography (CT) scans. Radiographs and CT scans of 25 patients evaluated predominantly for glenohumeral joint instability and 25 patients after implantation of a total shoulder prosthesis were analyzed by 3 independent observers. In all patients glenoid version was determined on an axillary view and on a CT scan at the mid-glenoid level. The mean glenoid version measured on CT scans was 3 degrees of retroversion in the instability group (range, 7 degrees of anteversion to 16 degrees of retroversion) and 2 degrees of anteversion in the total shoulder prosthesis group (range, 16 degrees of anteversion to 23 degrees of retroversion). Glenoid retroversion was overestimated on plain radiographs in 86%. The mean difference between measurements of glenoid version on axillary views and CT cuts was 6.5 degrees (range, 0 degrees -21 degrees ), and the coefficient of correlation between these measurements was 0.33 in the instability group and 0.67 in the prosthesis group. In conclusion, glenoid version cannot be determined accurately on standard axillary radiographs, either preoperatively or postoperatively. Studies that assess the role of glenoid component orientation should use a reproducible method of assessment such as CT.

Arthroplasty, Replacement↗

PubMedDate not supplied

Failure of suture material at suture anchor eyelets.

PURPOSE: In the repair of soft tissue to bone using suture anchors, failure of the suture material can occur at the anchor eyelet. This study examines the load strength at which suture material fails with different metallic suture anchor eyelets. TYPE OF STUDY: Biomechanical study. METHODS: Suture material (Ethibond No. 2, Ethicon, Norderstedt, Germany) was pulled out from 22 metallic suture anchor models at 60 mm/min, and tensile load at failure and failure mode were recorded. Tests were performed either by simultaneous pulling on 2 suture limbs in 3 different directions (straight, at 45 degrees, and at 45 degrees rotated by 90 degrees to the suture anchor axis) or by pulling on 1 suture limb while measuring the resulting force on the second limb. All tests were performed until suture failure. Pulling was performed in single tests on an Instron materials testing machine (High Wycombe, UK), with the anchors held by a vise. RESULTS: In all cases, the suture failed at the anchor eyelet. Failure load at straight loading ranged from 116 +/- 5 N to 226 +/- 5 N and from 69 +/- 5 N to 193 +/- 7 N when loaded at an angle of 45 degrees. The best results were found with the Statak 5.2-mm (Zimmer, Warsaw, IN): 177 N; Corkscrew 6.5-mm anchor (Arthrex, Naples, FL): 174 N; and PeBA 4.0-mm anchor (OBL Orthopaedic Biosystems, Scottsdale, AZ): 169 N. With each eyelet, sutures failed preferentially in 1 direction, depending on the presence of sharp edges. CONCLUSIONS: Suture material can be cut at suture anchor eyelets. Failure load depends on sharp edges on the eyelet and occurs at forces up to 73% below the breaking strength of the suture material on a smooth hook. Anchors with suture-protecting channels are particularly sensitive to the orientation in which the sutures are loaded.

Equipment Design↗

PubMedDate not supplied

The results of functional (Sarmiento) bracing of humeral shaft fractures.

At the Department of Orthopaedics of the Kantonsspital Fribourg, 67 humeral shaft fractures were treated by Sarmiento bracing in a 15-year period. There were 54 isolated fractures and 13 fractures sustained as a component of polytrauma. Fifty-eight cases (87%) had healed clinically at a mean of 10 weeks; 9 cases failed to heal, so further treatment was carried out operatively. Of the conservatively managed fractures, 95% (55 cases) healed with an excellent or good result. Three patients noted a slight limitation of active range of motion, but all 58 patients returned to full duty at their jobs. Among 9 patients with delayed or nonunion leading to operative intervention, there were 6 cases with transverse fractures. Major reasons for failed conservative management were an incorrect indication, a significant axial deformity, or a hyperextended position of the fracture fragments. In our experience, active repositioning of humeral shaft fractures is not effective in avoiding a delay in fracture healing. The decision to use functional bracing in polytrauma patients should depend on the time of expected bedridden immobilization, on the presence of additional fractures of the ipsilateral upper extremity, and on the patient's need for crutches. The conservative treatment of humeral shaft fractures with the Sarmiento brace remains the treatment of choice, in spite of newer intramedullary operations that are allegedly minimally invasive and technically less complicated.

Adult↗

PubMedDate not supplied

Shoulder instability related to epileptic seizures.

Epileptic seizures can cause shoulder dislocation and instability, but a characteristic pattern of instability and structural lesions is not well known. We reviewed 34 shoulders in 26 patients in whom the initial dislocation had been caused by an epileptic seizure. All patients were followed up clinically and radiologically for a mean of 10 years (range, 2-21 years) after initiation of treatment. Thirteen patients (17 shoulders) were treated for anterior instability. A large Hill-Sachs lesion was found 12 times and a large glenoid rim fracture 5 times. There were 12 recurrent and 2 locked dislocations. The recurrence rate after the first repair was 47% (8/17 shoulders). The final overall results at a mean follow-up of 10 years (range, 2-12 years) were good in 12 cases, satisfactory in 2, and unsatisfactory in 2. The reoperation rate was 40%. With skeletal reconstruction, 12 of 13 shoulders were stable at final follow-up. Another 13 patients (17 shoulders) were treated for posterior dislocation. A large reverse Hill-Sachs lesion was observed 13 times and a posterior glenoid rim fracture twice. There were 15 locked but only 2 recurrent dislocations. The recurrence rate after repair was 12% (2/17 shoulders). The final outcome at a mean follow-up of 7 years (range, 2-12 years) was good in 11 shoulders and satisfactory in 6. The reoperation rate was 12%. Anterior and posterior dislocations occurred with equal frequency in this series. Large bony lesions were the hallmark finding in this group of patients. Skeletal reconstruction was necessary to obtain clinical stability, especially in the more difficult-to-treat anterior instability.

Adolescent↗