Effects of protective knee bracing on speed and agility

We evaluated the effects of prophylactic knee braces on athlete speed and agility, as well as brace tendency to migrate. Thirty college football players in full gear ran a 40-yard dash and a four-cone agility drill wearing braces on both knees or no brace (control). Braces included the DonJoy Legend, Breg Tradition, OMNI-AKS 101W, McDavid Knee Guard, and models 1 and 2 of the Air Armor Knee and Thigh Protection System. Brace migration and subjective measures were recorded after each trial. In the 40-yard dash, times using Air Armor 1 and OMNI did not differ significantly from control. Times with other braces were significantly slower. In the four-cone drill, only the Breg times were significantly slower than control. The Air Armor 1 and McDavid braces showed significantly less superior/inferior migration in the 40-yard dash than other braces. In the four-cone drill, the Air Armor 1 and 2 showed significantly less superior/inferior migration than other braces. These findings indicate that selected knee braces do not significantly reduce speed or agility. Braces showed a variable tendency to migrate, which could affect their protective function and athlete performance. This information will help athletes and coaches decide about knee-brace use during sports; studies are needed regarding whether braces protect against knee injury. This study does not constitute an endorsement of knee-brace use or efficacy.

Polycaprolactone/glass bioabsorbable implant in a rabbit humerus fracture model

Research in improved materials and methods for internal fixation has centered on internal fixators made of bioabsorbable materials such as polylactic acid, polyglycolic acid, and polyparadioxanone. These materials have two problems: the first is a postoperative complication related to a delayed inflammatory response; and the second is low strength characteristics. An alternative material developed to alleviate these problems is a composite of phosphate glass fibers embedded in the polymer polycaprolactone, referred to as PCL. In this study, intramedullary pins made of PCL were compared to stainless steel pins in a rabbit humerus osteotomy model. Specimens were harvested at 0, 6, and 12 weeks postoperatively, radiographs and mechanical testing to failure were performed at each time interval, and tissue was examined microscopically at 6 and 12 weeks. Histologic results showed PCL pins to be well tolerated with minimal inflammation around the pin. Mechanical testing revealed the PCL fixation to be weaker initially than the stainless steel fixation. There was significant stress shielding of stainless-steel-healed rabbit humeri when compared to the PCL/bone humeri. All osteotomies immobilized with PCL healed with abundant periosteal callus production.

Preliminary experience with a novel model assessing in vivo mechanical strength of bone grafts and substitute materials

A novel canine tibia model was used to evaluate four bone graft materials: autologous cortical bone, allograft cortical bone, hydroxyapatite/tricalcium phosphate (HA/TCP) ceramic granules, and a HA/TCP and collagen composite. Mechanical material properties were assessed using custom-designed stainless steel plugs for control of graft volume and interface surface area. These plugs held the bone graft materials in the cortex of the tibia shaft and allowed in vivo mechanical testing. After 6 months of ad lib weight bearing, the grafts were harvested and tested in torsion. The samples in each animal were compared with the test plugs into which new bone had grown without the addition of graft. Control bone peak shear strength averaged 47 (+/- 8.3) MPa (6.78 +/- 1.2 kpsi). Compared on the basis of peak torque, stiffness, and energy to peak torque, no significant differences were found among any of the graft materials or control bone. Histologic examination revealed the materials to be osteoconductive with the extensive formation of dense, compact cancellous bone. The new bone in the autograft and allograft samples completely filled the available space, whereas gaps persisted in the synthetic ceramics.

Dermal nerve sheath myxoma of the hallux: a case report

Dermal nerve sheath myxoma is a rare tumor with a predilection for the upper extremity, head, neck, and shoulder. It usually arises during childhood or early adult life. We present a case of a young woman who has this type of myxoid tumor of the hallux. To preserve viability of the hallux, debulking of the tumor was performed rather than complete marginal excision. This case and a literature review suggest that this tumor may be satisfactorily managed with debulking or marginal resection. Histology and pathology of dermal nerve sheath myxoma are reviewed.