Biomedical subjects

M Schaffler

Publications and source records attributed to M Schaffler.

3 recordsLinked to original sources

PubMed1997

The interosseous membrane affects load distribution in the forearm.

The role of the interosseous membrane in load sharing was defined by simultaneously quantitating loads in the distal radius and ulna and in the proximal radius and ulna with an axial load to the wrist, before and after transecting the interosseous membrane. With the interosseous membrane intact, the load at the proximal ulna was greater than at the distal ulna and the load at the proximal radius was less than at the distal radius, suggesting that force was transferred from the radius distally to the ulna proximally. The average percentage of the total load in each bone in supination was as follows: distal radius, 68%; distal ulna, 32%; proximal radius, 51%; proximal ulna, 49%. After interosseous membrane division, the proximal and distal load values became equal in each bone, in all forearm positions, demonstrating that without the membrane there was no load transfer between the radius and ulna. The interosseous membrane transfers load from the wrist to the proximal forearm, via fibers that run from the proximal radius to the distal ulna and exert a proximally directed pull on the ulnar shaft.

Biomechanical Phenomena↗

PubMed1995

Rotator-cuff changes in asymptomatic adults. The effect of age, hand dominance and gender.

We studied the integrity of the rotator cuff in both dominant and non-dominant shoulders of 90 asymptomatic adults between the ages of 30 and 99 years using ultrasound. The criteria for diagnosis had been validated on unembalmed cadaver specimens. We found no statistically significant difference in the incidence of impingement findings between dominant and non-dominant arms or between genders. The prevalence of partial- or full-thickness tears increased markedly after 50 years of age: these were present in over 50% of dominant shoulders in the seventh decade and in 80% of subjects over 80 years of age. Our results indicate that rotator-cuff lesions are a natural correlate of ageing, and are often present with no clinical symptoms. Treatment should be based on clinical findings and not on the results of imaging.

Adult↗

PubMed1991

Anatomic consideration for sacral screw placement.

Instrumentation of the lumbosacral spine increasingly involves screw fixation to the sacrum. Recommended locations and techniques for screw placement vary, particularly when bicortical purchase of the sacrum is performed. The purpose of this study was to describe the critical anatomy and potential injuries to neurovascular and visceral structures anterior to the sacrum. Lack of awareness can lead to life-threatening complications. The study included 22 fresh human cadavers with no prior spinal surgery. Specimens were placed in a prone position, and the lumbosacral spine was exposed. Two 6.5-mm screws were inserted using one of two techniques, respectively: Starting just inferior to the S1 facet one screw was angled 25 degrees caudally and 30 degrees laterally; in the second technique, lateral inclination was increased to 45 degrees. In addition, all specimens had screws placed in the S2 pedicles. An anterior dissection was performed to allow evaluation of the neurovascular and visceral structures at risk for injury by, or adjacent to, the screw tips. All significant neurovascular structures in the area of concern were constant in position. The internal iliac vein and the lumbosacral nerve trunk were most at risk for injury by the 30 and 45 degrees laterally directed screws. The sigmoid colon, though close to the S2 screw, was protected by its mesentery. Screws placed in the S1 pedicle were least likely to injure the neurovascular bundle. A lateral and a midline safe zone were identified.

Aged↗