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Biomedical subjects

Benjamin Shaffer

Publications and source records attributed to Benjamin Shaffer.

6 recordsLinked to original sources

Rupture of the biceps tendon after arthroscopic thermal capsulorrhaphy.

The use of thermal energy in the shoulder to tighten capsular tissues through collagen denaturation is well established. Although reported complication rates are low, the natural history of thermal manipulation to both target and collateral tissue is poorly defined. We report two cases of biceps tendon rupture after arthroscopic capsular shrinkage. Both patients were young, athletic men with normal long head biceps tendons at the time of surgery. Each patient experienced a complete tear of the long head with distal muscle retraction, resulting in a "Popeye" deformity, at 3 months postoperatively. One patient elected further surgery with biceps tenodesis. Both patients have returned to their athletic activities with minimal functional deficits.

Adolescent↗

Scientific basis of laser energy.

Lasers are intense beams of energy generated through the stimulation of radiation. Their clinical appeal in arthroscopic applications is based on their preferential absorption by water-containing tissues. Laser-tissue interaction includes reflection, scattering, transmission, and absorption. Clinical effects occur through tissue heating by absorption of laser energy. When power density is sufficient to achieve the ablation threshold, vaporization of tissue results with minimal collateral thermal damage. Further developments in the field of laser medicine may provide us with arthroscopic tools of even greater precision and safety.

Arthroscopy↗

Simulated graft recession in endoscopic ACL reconstruction: influence on graft strain.

Eight fresh cadaveric knee specimens underwent arthroscopic-assisted ACL reconstruction to examine the influence of femoral graft recession on graft strain pattern. Length changes between tibial origin and femoral insertion (simulating graft strain or isometry pattern) were measured throughout knee motion (0 degrees-90 degrees) with a simulated ACL construct. Measurements were taken at the "endo" position (replicating the normal endoscopic position) and in progressive 1.5-mm increments proximally within the femoral tunnel (mimicking femoral graft recession). After recession up to a maximum of 15 mm, a block was placed anterior to the "recessed" graft construct (simulating placement of bone graft anterior to the recessed graft) and strain patterns were remeasured. Graft strain patterns were altered with as little as 1.5 mm recession in two of eight specimens. Compared to the "endo" position, all specimens showed a statistically significant decrease in strain by 3 mm of graft recession (P<.001 for 7 of 8, and P=.0138 for 1 of 8). A direct relationship exists between graft placement and ACL strain patterns, with more proximal graft "recession" adversely influencing normal graft strain. Bone graft placement anterior to the recessed graft restores strain patterns to those seen at the normal "endoscopic" position.

Analysis of Variance↗