Regulation of reaction forces during the golf swing.

During the golf swing, the reaction forces applied at the feet control translation and rotation of the body-club system. In this study, we hypothesized that skilled players using a 6-iron would regulate shot distance by scaling the magnitude of the resultant horizontal reaction force applied to the each foot with minimal modifications in force direction. Skilled players (n = 12) hit golf balls using a 6-iron. Shot distance was varied by hitting the ball as they would normally and when reducing shot distance using the same club. During each swing, reaction forces were measured using dual force plates (1200 Hz) and three-dimensional kinematics were simultaneously captured (110 Hz). The results indicate that, on average, the peak resultant horizontal reaction forces of the target leg were significantly less than normal (5%, p < 0.05) when reducing shot distance. No significant differences in the orientation of the peak resultant horizontal reaction forces were observed. Resultant horizontal reaction force-angle relationships within leg and temporal relationships between target and rear legs during the swing were consistent within player across shot conditions. Regulation of force magnitude with minimal modification in force direction is expected to provide advantages from muscle activation, coordination, and performance points of view.

The effects of mitomycin-C and stenting on airway wound healing after laryngotracheal reconstruction in a pig model.

OBJECTIVE: To assess the effects of mitomycin-C (MTC) and endoscopic stenting on airway wound healing after laryngotracheal reconstruction. DESIGN: A prospective, blinded, randomized controlled animal study. SUBJECTS: Twenty-six domestic pigs (Sus scrofula) divided into four groups. INTERVENTIONS: Each animal underwent single-stage laryngotracheal reconstruction (SSLTR) with auricular cartilage grafts and stenting. Group 1 animals were sacrificed on postoperative day 3, and group 2 animals on postoperative day 7. On postoperative day 7, groups 3 and 4 underwent endoscopy, stent removal, and application of MTC (0.5 mg/ml) or placebo (normal saline). Group 3 animals were sacrificed on postoperative day 14, group 4 animals on day 21. Two additional animals from each experimental group were prepared for election microscopy studies. Segments of reconstructed airway were evaluated grossly and histologically for all animals. Additional tonometric evaluation was performed on two stents to determine their compressive strength. MAIN OUTCOME MEASURES: Healing, reepithelization, graft incorporation, and airway diameter. RESULTS: Two-thirds of the animals demonstrated some degree of stent collapse on endoscopy. Granulation tissue formation was seen in all animals, and resolved with stent removal. No animal experienced airway compromise due to granulation tissue formation. Stenting was seen to induce a submucosal fibroproliferative response and scarring, with loss of normal glandular architecture, in all animals. MTC did not affect the acute inflammatory response, reepithelization of the graft site, or formation of the subepithelial fibroproliferative response. MTC treated animals, however, demonstrated better graft incorporation with fibrocartilage proliferation of the graft. Untreated animals demonstrated liquefactive necrosis of the graft, without evidence of neochondrification of the graft. CONCLUSIONS: The pig airway is an adequate model of wound healing following SSLTR and stenting. Metallic ballon expandable stents can be successfully used following SSLTR, allowing for immediate postoperative extubation. However, the formation of a submucosal fibroproliferative response and mucosal scarring seen in our study raises some concerns with the current stent design. Before stenting is widely clinically applied, the optimum stent design needs to be developed. Finally, MTC seems to prevent the liquefactive necrosis of SSLTR grafts and promote neochondrification, allowing improved graft incorporation. Further studies are needed to asses the long-term effects of MTC on healing and restenosis, and its effects on cartilage growth and formation, following SSLTR.

Surgical excision of pilomatrixoma of the head and neck: a retrospective review of 26 cases.

The objective of this article is to describe our experiences in treating patients for head and neck pilomatrixoma at our institution during a 5-year period and to compare our findings with previously published results. To that end, we conducted a 5-year retrospective chart review to identify those patients who had a confirmed histopathologic diagnosis of pilomatrixoma involving the head and neck area. We reviewed medical records for presenting signs and symptoms, lesion characteristics, treatment rendered, and outcomes. We identified 26 patients, aged 6 to 77 (mean: 33), who met the criteria for inclusion in our study. All had been treated for solitary tumors with simple surgical excision and closure. We found no reported adverse outcomes and no tumor recurrences at the surgical sites. These findings support the use of simple surgical excision as the treatment of choice for these tumors.