Association between body mass index-for-age and slipped capital femoral epiphysis: the long-term risk for subsequent slip in patients followed until physeal closure.

BACKGROUND: Children who present with idiopathic slipped capital femoral epiphysis (SCFE) have an increased risk of developing bilateral disease. Predicting which patients will develop problems with bilateral hips is important for determining treatment algorithms. This is a retrospective observational study that evaluates the relationship and risk between body mass index (BMI)-for-age and unilateral and bilateral SCFE in patients followed until physeal closure. METHODS: This is a retrospective study of all patients with SCFE presenting to one institution from 1998-2005. Using the Center for Disease Control (CDC) references, BMI-for-age was calculated for each patient. The patients were followed up until complete closure of the bilateral proximal femoral physes, which was considered completion of the study. Statistical analysis for significant differences between groups was performed using the Kruskal-Wallis test for equality of populations. A logistic regression, controlling for age and gender, was used to identify BMI-for-age as a risk factor and to determine the significance of the odds ratios (ORs) for the relevant categorical variables-obese, overweight and healthy weight. RESULTS: Eighty patients (56 male, 24 female) presented to a single institution between 1998 and 2005 with a diagnosis of SCFE. The mean age of patients was 12.2 years at initial presentation (range 8.5-16). Forty-eight patients (32 male, 16 female) presented with unilateral SCFE, with 22 of the 48 patients having a BMI for-age percentile ≥95 %. Thirty-two patients (24 male, 8 female) presented with bilateral SCFE, with 29 of the 32 patients having a BMI-for-age percentile ≥95 %. Patients with a BMI-for-age ≥95 % had a significantly increased risk of presentation with bilateral slips (OR 4.83; relative risk [RR] 3.01; p < 0.05]. All but one patient in this study with bilateral SCFE or unilateral SCFE with subsequent contralateral involvement had a BMI-for-age ≥85 % (44 out of 45 patients). Additionally, the overall risk of developing bilateral SCFE until physeal closure with a BMI-for-age ≥95 % was significantly increased (OR 3.84; RR 2.02; p < 0.05; number needed to treat [NNT] 3.01). CONCLUSIONS: Previous work has established a relationship between BMI and SCFE. The CDC BMI-for-age growth charts more accurately measure obesity in the pediatric population compared to BMI and are therefore a more appropriate reference tool. This study demonstrates an association between obesity measured by BMI-for-age percentiles and SCFE. This study also demonstrates an association between BMI-for-age and risk for bilateral SCFE at presentation as well as overall incidence of developing bilateral SCFE in the obese pediatric population. By defining the at-risk population through BMI-for-age, physicians can screen the pediatric patient population and provide early strategies for therapeutic weight loss which may reduce the incidence of SCFE.

Contribution of Round vs. Rectangular Expandable Cage Endcaps to Spinal Stability in a Cadaveric Corpectomy Model.

BACKGROUND: Expandable cages are gaining popularity in anterior reconstruction of the thoracolumbar spine following corpectomy as they can provide adjustable distraction and deformity correction. Rectangular, rather than circular, endcaps provide increased resistance to subsidence by spanning the apophyseal ring; however their impact on construct stability is not known. The objective of this study was to investigate the contribution of expandable corpectomy cage endcap shape (round vs. rectangular) and fixation method (anterior plate vs. posterior pedicle screws) to the stability of an L1 sub-total corpectomy construct. METHODS: Eight fresh-frozen cadaveric specimens (T11-L3) were subjected to multi-directional flexibility testing to 6 N·m with a custom spine simulator. Test conditions were: intact, L1 sub-total corpectomy defect, expandable cage (round endcap) alone, expandable cage (round endcap) with anterior plate, expandable cage (round endcap) with bilateral pedicle screws, expandable cage (rectangular endcap) alone, expandable cage (rectangular endcap) with anterior plate, expandable cage (rectangular endcap) with bilateral pedicle screws. Range-of-motion across T12-L2 was measured with an optoelectronic system. RESULTS: The expandable cage alone with either endcap provided significant stability to the corpectomy defect, reducing motion to intact levels in flexion-extension with both endcap types, and in lateral bending with rectangular endcaps. Round endcaps allowed greater motion than intact in lateral bending, and axial rotation ROM was greater than intact for both endcaps. Supplemental fixation provided the most rigid constructs, although there were no significant differences between instrumentation or endcap types. CONCLUSIONS: These results suggest anterior-only fixation may be adequate when using an expandable cage in a sub-total corpectomy application and choice of endcap type may be driven by other factors such as subsidence resistance.

Anterior column realignment (ACR) for focal kyphotic spinal deformity using a lateral transpsoas approach and ALL release.

STUDY DESIGN: Retrospective case series. OBJECTIVES: Introduce and evaluate the safety of a new technique of anterior column realignment (ACR) using a lateral transpsoas approach with release of anterior longitudinal ligament and annulus for correction of focal kyphotic deformity. SUMMARY OF BACKGROUND DATA: Spinal sagittal imbalance can adversely affect the long-term outcomes of patients with spinal deformity. METHODS: Clinical and radiographic review of patients who underwent ACR. RESULTS: Seventeen consecutive patients (12 females; 5 males) with a mean age of 63 years (range, 35-76 y) and a mean follow-up of 24 months (range, 12-82 mo) were identified. Fourteen of 17 (82%) had previous spine surgery and 12/17 (71%) had previous fusion. Twelve of the 17 (71%) underwent ACR for adjacent segment disease. Fifteen patients (88%) had Smith-Petersen osteotomies at the ACR level.The mean motion segment angle was 9 degrees preoperatively, which corrected to -19 degrees after ACR and to -26 degrees after posterior instrumentation. Motion segment angle was maintained at -23 degrees at the latest follow-up. The mean lumbar lordosis was -16 degrees preoperatively, which improved to -38 degrees after ACR and to -45 degrees after posterior instrumentation. Lumbar lordosis was maintained at -51 degrees at the latest follow-up. Pelvic tilt averaged 34 degrees before ACR and improved to 24 degrees after ACR and posterior instrumentation and maintained at 25 degrees at the latest follow-up. Patients with preoperative negative T1 spinopelvic inclination (T1SPI) corrected from -6 to -2 degrees and those with 0 or positive T1SPI corrected from 5 to -3 degrees after ACR at the latest follow-up.Eight patients (47%) had 10 complications. Four complications occurred after ACR. Two of 4 were neurological (1 persistent weakness) and 1 was vascular injury during anterior plate removal. CONCLUSION: Compared with posterior-based techniques, our preliminary results of ACR showed similar correction capacity and similar rate of morbidities for the treatment of focal kyphotic spinal deformity. Careful case selection, attention to the details of the technique, and enough experience are prudent elements for a desirable outcome.

Type II supracondylar humerus fractures: can some be treated nonoperatively?

BACKGROUND: The range of injury severity that can be seen within the category of type II supracondylar humerus fractures (SCHFs) raises the question whether some could be treated nonoperatively. However, the clinical difficulty in using this approach lies in determining which type II SCHFs can be managed successfully without a surgical intervention. METHODS: We reviewed clinical and radiographic information on 259 pediatric type II SCHFs that were enrolled in a prospective registry of elbow fractures. The characteristics of the patients who were treated without surgery were compared with those of patients who were treated surgically. Treatment outcomes, as assessed by the final clinical and radiographic alignment, range of motion of the elbow, and complications, were compared between the groups to define clinical and radiographic features that related to success or failure of nonoperative management. RESULTS: During the course of treatment, 39 fractures were found to have unsatisfactory alignment with nonoperative management and were taken for surgery. Ultimately, 150 fractures (57.9%) were treated nonoperatively, and 109 fractures (42.1%) were treated surgically. At final follow-up, outcome measures of change in carrying angle, range of motion, and complications did not show clinically significant differences between treatment groups. Fractures without rotational deformity or coronal angulation and with a shaft-condylar angle of >15 degrees were more likely to be associated with successful nonsurgical treatment. A scoring system was developed using these features to stratify the severity of the injury. Patients with isolated extension deformity, but none of the other features, were more likely to complete successful nonoperative management. CONCLUSIONS: This study suggests that some of the less severe pediatric type II SCHFs can be successfully treated without surgery if close follow-up is achieved. Fractures with initial rotational deformity, coronal malalignment, and significant extension of the distal fragment are likely to fail a nonoperative approach. An algorithm using the initial radiographic characteristics can aid in distinguishing groups.

Coronal shear fracture of the distal humerus in an 11-year-old patient.

Coronal shear fractures of the distal humerus are uncommon in the pediatric population. We present the case of an 11-year-old girl who sustained a coronal shear fracture of the distal humerus, requiring open reduction and internal fixation with the use of headless screws. At the time of the latest follow-up, she had fully recovered the range of motion on the affected limb, had returned to full physical activities without limitations, radiographs showed a completely healed fracture with restoration of the articular line, and there was no signs of avascular necrosis of the capitellum.

Estrogen-dependent actions of bone morphogenetic protein-7 on spine fusion in rats.

STUDY DESIGN: Intertransverse process spinal fusion using recombinant human bone morphogenetic protein-7 (rhBMP-7) was performed in intact and ovariectomized female rats. OBJECTIVES: To examine fusion rates in intact and ovariectomized female rats using rhBMP-7 to determine if spine fusion is dependent on estrogen status. SUMMARY OF BACKGROUND DATA: Rat spinal fusion has been established as a consistent, efficient model for posterolateral intertransverse process fusion. Previous experiments have confirmed the efficacy of pellets containing the carrier, insoluble collagen bone matrix (ICBM), and rhBMP-7 to augment intertransverse process single level fusion in a rat model. Studying these implications in an osteoporosis model is of clinical value because there are many patients undergoing spinal fusion surgery that have osteoporotic bone disease, and there is a steady increase in this group of patients. METHODS: A total of 15 ovariectomized and 15 intact Sprague-Dawley female rats were randomly assigned to groups receiving 25 mg ICBM alone, 25 mg ICBM + 10 microg rhBMP-7, and 25 mg ICBM + 30 microg rhBMP-7. Spinal fusion was evaluated by manual motion testing at each lumbar segment, radiographic evaluation using the Lenke grading system, and histology. RESULTS: Ovariectomized and intact rats receiving 25 mg carrier ICBM alone did not show spinal fusion. With 25 mg ICBM + 10 microg rhBMP-7, there was not a significant difference in fusion rates between intact and ovariectomized rats (P = 0.63). Ovariectomized rats receiving 25 mg ICBM + 30 microg rhBMP-7 showed significantly lower fusion rates than intact rats (P = 0.013). CONCLUSION: These data suggest that spinal fusion using rhBMP-7 is estrogen-dependent in rats. At the dosages used, rhBMP-7 was unable to overcome the inhibitory effects of estrogen deficiency on spinal fusion.