Biomechanical analysis of tibial strength after harvesting unicortical tibial grafts of two different lengths.

BACKGROUND: It is not known whether the use of the proximal tibia as a source of strut graft compromises the strength of the tibia. Our hypothesis was that unicortical proximal tibial grafts in two different sizes would not significantly decrease the torsional strength of the tibia. MATERIALS AND METHODS: Ten matched pairs of human cadaver tibiae were stripped of all soft tissues. One tibia in each pair was randomly assigned to receive an osteotomy of 2 x 1.5 cm or 6 x 1.5 cm placed 1 cm dorsal to the tibial crest with the proximal graft edge 6 cm from the tibial plateau. Specimens were loaded at 720 N and in external rotational torque at 5 degrees per second to failure. Axial force or torque at failure were analyzed via T-test (p < or = 0.05). RESULTS: There was no significant difference in torque to failure between specimens with an osteotomy of 1.5 x 2 cm versus the matched intact specimens. Torque to failure for specimens with an osteotomy 1.5 x 6 cm was lower than that of the matched intact specimens (28.69 Nm +/- 4.2 Nm versus 60.95 Nm +/- 9.49 Nm; p = 0.01) and lower than that found in the 2-cm osteotomy group (p = 0.04). CONCLUSION: Torque to failure was significantly decreased with the larger 6-cm graft as compared with the intact tibia and with the graft 1.5 x 2 cm. The smaller graft did not result in a significant change in torsional strength of the tibia. CLINICAL RELEVANCE: Though this study cannot be extrapolated directly to the clinical setting, the longer graft tested in this study may raise concerns regarding the strength of the tibia after graft removal.

Radiographic parameters of increased carpal tunnel pressure with progressive wrist distraction: a cadaveric study.

PURPOSE: Increased carpal canal pressure associated with external fixation has been noted as a potential source of complications but no correlated clinical observation has been identified. We hypothesized that there would be a significant change in midcarpal distance and modified carpal height index with increasing distraction across the wrist joint and that these changes would correlate with pressure increases. METHODS: Thirteen cadaveric upper extremities were mounted vertically using 2 half pins in the midradius. Using a previously reported technique, we introduced a balloon-tipped catheter attached to a transducer into the carpal canal for pressure measurement. As weights were hung from the middle finger to create distraction across the carpus, pressure measurements and radiographs of the wrist were taken simultaneously. This sequence was performed for 4.50 kg of distraction in 0.45-kg increments and at 6.80 and 9.07 kg of distraction with the wrist in neutral position. Changes in midcarpal distance and modified carpal height index were calculated and comparisons were made with the Student t test. A 2-tailed Pearson correlation was used to determine whether there was a correlation between carpal canal pressure and radiographic indicators. Significance was set at p

Plantar-to-dorsal compared to dorsal-to-plantar screw fixation for proximal chevron osteotomy: a biomechanical analysis.

BACKGROUND: A change in screw orientation in fixing the chevron proximal first metatarsal osteotomy was noted anecdotally to improve fixation strength. The authors hypothesized that plantar-to-dorsal screw orientation would be more stable than the conventional dorsal-to-plantar screw orientation for fixation of the chevron osteotomy. The purpose of this study was to determine if the load-to-failure and stiffness of the chevron type proximal first metatarsal osteotomy stabilized using plantar-to-dorsal screw fixation were greater than with the more conventional dorsal-to-plantar screw fixation method. METHODS: One foot from each of eight matched cadaver pairs was randomly assigned to one of two groups: 1) fixation with a dorsal-to-plantar lag screw or 2) fixation with a plantar-to-dorsal lag screw. A proximal chevron osteotomy was then created using standard technique and the metatarsal was fixed according to previously established method. The bone was potted in polyester resin, and the construct was fitted into a materials testing system machine in which load was applied to the plantar aspect of the metatarsal until failure. The two groups were compared using a two-tailed Student t test. RESULTS: The average load-to-failure and stiffness of the chevron osteotomy fixed with the plantar-to-dorsal lag screw were significantly greater (p < 0.05) than the group fixed with more conventional dorsal-to-plantar lag screws. CONCLUSION: Plantar-to-dorsal screw orientation was more stable than the conventional dorsal-to-plantar screw orientation for fixation of the proximal chevron osteotomy. Plantar-to-dorsal screw orientation should be considered when using the chevron proximal first metatarsal osteotomy.

Epidemiology of lacrosse injuries in high school-aged girls and boys: a 3-year prospective study.

OBJECTIVE: To report the types, mechanisms, and circumstances of lacrosse injuries incurred by high school-aged girls and boys during organized interscholastic and summer camp games. STUDY DESIGN: Descriptive epidemiology study. METHODS: For 3 years, the authors gathered data on girls' and boys' lacrosse injuries for 359 040 high school and 28 318 summer camp athletic exposures using a lacrosse-specific computerized injury surveillance system. The most prevalent injuries were organized into multifactorial injury scenarios. RESULTS: In high school play, the injury rate for adolescent boys (2.89 per 1000 athletic exposures) was slightly higher than that for girls (2.54 per 1000 athletic exposures) (incidence rate ratio = 1.14; 95% confidence interval, 1.00-1.30). The most prevalent injuries for adolescent girls and boys were knee and ankle sprains resulting from noncontact mechanisms. Male players had significantly higher rates of shoulder, neck, trunk, and back injuries and higher game-to-practice injury ratios. In addition, they had higher rates of concussive events from player-to-player contact. Female players had higher rates of overall head injuries, many involving contusions and abrasions from stick and ball contact. CONCLUSIONS: The overall injury rates for boys' and girls' high school lacrosse were significantly lower than those for collegiate play. Significant differences existed between adolescent boys and girls with respect to injury mechanisms, body parts injured, and player and team activity at the time of injury.

Acute and recurrent patellar instability in the young athlete.

Many reports of patellofemoral instability treatment suffer the same flaws of inappropriate patient selection, poor injury definition, insufficient activity assessment, and, especially in skeletally immature patients, limited followup found in other orthopedic literature. A significant number of dogmatic statements concerning risk factors and treatment interventions continue to be recycled through the literature without adequate clinical or laboratory substantiation, even in the face of contradictory data. Traditionally, patellar instability has been treated with variable periods of immobilization, sporadic rehabilitation, and an expected full return to sports activity. The reality is that many young athletes have long-term retropatella pain and sport-limiting extensor mechanism impairment following patellar dislocations. Most athletes benefit from an initial nonoperative program that is aggressive, multidimensional, and responsive to early treatment outcomes. Concurrent osteochondral injuries are common and a major contributor to adverse outcomes. Diagnostically, MRI is improving in its ability to detail osteochondral injury and it plays an important role in determining the location and extent of MPFL injury. The primary stabilizing role of the MPFL in the normal knee and its injury as an essential lesion of patella instability has been appreciated only recently. There is growing interest in exchanging the myriad of nonanatomic extensor mechanism reconstructions for more anatomic procedures based on restitution of the MPFL.