Preoperative measurement of the thickness of the center of the humeral head predicts screw cutout after locked plating of proximal humeral fractures.

HYPOTHESIS AND BACKGROUND: Preoperative computed tomography (CT) scans can be used to measure the thickness of the center of the humeral head to identify patients at a higher risk of screw cutout after open reduction-internal fixation. METHODS: At an academic medical center, we performed a retrospective review of all patients aged ≥ 18 years who had sustained a proximal humeral fracture that was treated with open reduction-internal fixation between January 1, 2005, and December 31, 2014, and who underwent preoperative shoulder CT. Ninety-four patients were included. Patient charts were reviewed to obtain demographic data, and radiographs were reviewed to assess screw cutout. A standardized method was devised to measure the thickness of the center of the humeral head. RESULTS: Screw cutout developed in 17 patients (17.7%). The mean humeral head thickness was significantly smaller on the axial (18 mm vs. 21 mm, P = .0031), coronal (18 mm vs. 21 mm, P = .0084), and sagittal (18 mm vs. 21 mm, P = .0033) sections in the patients who experienced screw cutout. When the smallest of the 3 measurements for each patient was analyzed, the risk of cutout was markedly greater when the humeral head thickness was <20 mm (25% vs. 6%). In addition, when the humeral head thickness was >25 mm, the risk of cutout was reduced to 0%. A low-energy injury was associated with a lower risk of cutout whereas age, sex, and fracture classification were not independent predictors of cutout on multivariate logistic regression. CONCLUSIONS: In a patient with a proximal humeral fracture in whom a preoperative CT scan is available, calculating the thickness of the center of the humeral head may provide valuable information to both the surgeon and the patient for preoperative planning and counseling. A smaller thickness of the center of the humeral head on preoperative CT is predictive of screw cutout following locked plating of proximal humeral fractures. A measurement of >25 mm in any one plane is highly protective against cutout; however, extreme caution and consideration of supplemental fixation methods should be taken when the measurements in all planes are <15 mm. This information may be helpful in counseling patients regarding the possibility of postoperative screw cutout.

Radiographic Review of Helical Blade Versus Lag Screw Fixation for Cephalomedullary Nailing of Low-Energy Peritrochanteric Femur Fractures: There is a Difference in Cutout.

OBJECTIVES: To compare the rate of cutout of helical blades and lag screws in low-energy peritrochanteric femur fractures treated with a cephalomedullary nail (CMN). DESIGN: Retrospective review. SETTING: Academic medical center. PATIENTS: Overall, this study included 362 patients with an average age of 83 year old, a majority of whom were women, and had sustained a low-energy peritrochanteric femur fracture treated with a CMN. All patients had at least 3 months of clinical and radiographic follow, with an average follow-up of 11 months and a range of 3-88 months follow-up. INTERVENTION: Cephalomedullary nailing with the use of a helical blade or single lag screw for proximal fixation. MAIN OUTCOME MEASUREMENTS: Cutout of the helical blade or lag screw. RESULTS: Twenty-two cutouts occurred, 14 (15.1%) of 93 patients with helical blades and 8 (3.0%) of 269 patients with lag screws. Cutout with the helical blade was significantly more frequent than with the lag screw (P = 0.0001). The average tip-apex distance (TAD) was significantly greater for those patients who experienced cutout both for the helical blades (23.5 vs. 19.7 mm; P = 0.0194) and lag screws (24.5 vs. 20.0 mm; P = 0.0197). An absolute TAD predictive of cutout could not be determined. CONCLUSIONS: When the helical blade was used, implant cutout occurred at a significantly higher rate compared with lag screw fixation. There was not a threshold TAD that was predictive of cutout for either implant. LEVEL OF EVIDENCE: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Nail gun injury to the sacrum: case report and review of the literature.

STUDY DESIGN: Case report. OBJECTIVE: Review the literature that relates to nail gun injuries to the spine using a case report illustration. SUMMARY OF BACKGROUND DATA: Approximately 37,000 patients present to the US emergency departments annually with injuries inflicted from nail guns, 60% of which occur in the workplace. METHODS: A case report of a nail gun injury to the sacrum is presented and the pertinent literature is then reviewed. RESULTS: A 21-year-old male roofer presented to the emergency department after suffering an accidental, self-inflicted nail gun injury to the midline of his sacrum. The patient was neurologically intact and a computed tomography (CT) of the pelvis with rectal contrast noted the nail to be located midline within the spinal canal at the level of S3 without injury to the rectum. The patient was taken to the operating room for removal of the nail under general anesthesia and exploration of the wound, specifically looking for evidence of a dural tear, which was determined not to be present. The wound was closed primarily and the patient was given 24 hours of intravenous antibiotics followed by 2 weeks of oral antibiotics. At follow-up, the patient had returned to his roofing job full-time and there was no evidence of infection on examination or retained foreign bodies by radiograph. CONCLUSION: On the basis of our experience and a review of the literature, in terms of treating a nail gun injury to the sacrum we recommend the following: exploration in the operating room to investigate the possibility of a dural tear, thorough irrigation, and debridement, especially in the case of barbed nails, and consultation with general surgery to determine if there is any injury to intrapelvic contents before surgery. An infectious disease consultation postoperatively may also assist in proper selection and duration of antibiotic therapy.

Near-terminal creep damage does not substantially influence fatigue life under physiological loading.

Cortical bone specimens were damaged using repeated blocks of tensile creep loading until a near-terminal amount of creep damage was generated (corresponding to a reduction in elastic modulus of 15%). One group of cortical bone specimens was submitted to the near-terminal damage protocol and subsequently underwent fatigue loading in tension with a maximum strain of 2000 µÎµ (Damage Fatigue, n=5). A second group was submitted to cyclic fatigue loading but was not pre-damaged (Control Fatigue, n=5). All but one specimen (a damaged specimen) reached run-out (10 million cycles, 7.7 days). No significant differences in microscopic cracks or other tissue damage were observed between the two groups or between either group and additional, completely unloaded specimens. Our results suggest that damage in cortical bone allograft that is not obvious or associated with a stress riser may not substantially affect its fatigue life under physiologic loading.