Biomechanical evaluation of the risk of secondary fracture around short versus long cephalomedullary nails.

INTRODUCTION: For proximal femur fractures, long cephalomedullary nails (CMNs) are often selected to avoid a diaphyseal stress riser at the tip of a shorter nail. Secondary peri-implant fracture rates for long and short CMN have not been shown to differ clinically. This study biomechanically compares both CMN in a cadaveric model. METHODS: Ten matched pairs of cadaveric femora with short or long CMN were axially loaded and internally rotated to failure. RESULTS: Resulting fractures involved distal interlocking screws of the short and long CMN. Energy and rotation to failure were significantly greater for short CMN. Torque at failure trended higher for short CMN but not significantly. No statistical difference was detected in stiffness of the short and long CMN. DISCUSSION: A greater risk of secondary fracture is not indicated for short versus long CMN under torsional stress. Short CMN may be suitable in the younger patient.

Mechanical effects of the extended trochanteric osteotomy.

BACKGROUND: The extended trochanteric osteotomy was introduced as a safe and effective exposure technique for revision hip surgery; however, intraoperative iatrogenic femoral fractures have been reported. This study examined the effects of the extended trochanteric osteotomy on the torsional strength of the femur with use of cadaver bones. We hypothesized that repair of the osteotomy fragment would restore the torsional strength to that of an intact femur and that an osteotomized femur containing a well-fixed stem would have the same torsional strength as an intact femur with a stem. METHODS: Fifty-eight cadaveric human femora were divided into five groups, according to the repair technique, to examine the effects of the extended trochanteric osteotomy: intact, osteotomy, repaired osteotomy, implant, and implant-repaired osteotomy. Osteotomy fragments were reattached with use of three double-looped 18-gauge wires. A femoral stem was cemented into the last two groups. Specimens were tested mechanically in rotation until failure. Rotational properties were compared with one-way analysis of variance followed by post hoc pairwise comparisons. Linear regression analysis was performed for bone mineral density and torsional strength. RESULTS: Torque to failure was reduced by 73% for the specimens in the osteotomy group compared with the intact group (p < 0.0001). Repair of the osteotomy did not improve torque to failure (p > 0.99). Femora in the implant-repaired osteotomy group displayed significantly improved torque-to-failure values compared with the specimens in the osteotomy and repaired osteotomy groups (p < 0.0001). However, the strength of the femora in the implant-repaired osteotomy group remained significantly less than that of the specimens in the implant group (p < 0.007). A significant linear relationship was observed between bone mineral density and torque to failure for femora in the intact (p < 0.006), osteotomy (p < 0.002), and repaired osteotomy (p < 0.001) groups. CONCLUSIONS: The extended trochanteric osteotomy reduces torsional strength by 73% even when the osteotomy fragment is repaired. Bone mineral density directly affects absolute femoral strength in this model.

Open extremity fractures: impact of delay in operative debridement and irrigation.

BACKGROUND: Early (<8 hours) operative debridement and irrigation (D&I) of open fractures are considered essential to reduce the risk of deep infection. With the advent of powerful antimicrobials, this axiom has been challenged. The current study evaluates the rates of deep infections of open fractures in relation to the time to the first D&I. METHODS: A list of all blunt open fractures during a 6-year period was obtained from the trauma registry. Patients were evaluated for age, Injury Severity Score (ISS), physiologic derangement (systolic blood pressure, lactate, Revised Trauma Score [RTS]), and fracture type (Gustilo). Time to the first D&I was calculated. All patients received appropriate prophylactic antimicrobials. Infection rates were calculated and correlated to the time to the first D&I (<8 hours vs. >8 hours). Regression analysis was performed to identify independent predictors of infection. RESULTS: During the 72-month study period, 404 patients met entry criteria, with 415 open extremity fractures (upper, 129; lower, 287). Early (<8 hours) and delayed (>8 hours) groups were well matched, although the age was lower and ISS was higher in the group with greater than 8 hours. The rates of infection were 35 (11%) of 328 (<8 hour) and 17 (19%) of 87 (>8 hours) (p < 0.05). When fractures were subgrouped by extremity, for the lower extremity, both a delay of greater than 8 hours and higher Gustilo type correlated with the development of infection. In the upper extremity, only higher Gustilo type correlated, and a delay to the first D&I did not increase the incidence of infection. Regression analysis revealed that higher ISS (odd ratio [OR], 1.052; 95% confidence interval [CI], 1.019-1.086), Gustilo grade, and a delay of greater than 8 hours (OR, 2.035; 95% CI, 1.022-4.054) were independent predictors of infection for the all-extremity model. Separate models for upper and lower extremities showed that the same three parameters were independent predictors for the lower extremity (ISS: OR, 1.045; 95% CI, 1.004-1.087; Gustilo type and >8-hour delay: OR, 3.006; 95% CI, 1.280-7.059), but none for the upper extremity. CONCLUSION: Delay of greater than 8 hours to the first D&I for open fractures of the lower extremity increases the likelihood of infection but not for the upper extremity. Higher Gustilo type open fractures have a higher incidence of infection for both upper and lower extremities. The results have important implications in an era of decreasing surgeon availability, especially in off hours. LEVEL OF EVIDENCE: Therapeutic study, level IV.

Peri-implant fracture of the femur in an 11-year-old: a case report.

Fracture of the femur in the area of a pre-existing implant is not common in an adolescent. We report the case of a fracture, in the area of a pre-existing implant in an 11-year-old boy, after a fall from a bike. We are not aware of any similar reports in the literature.