Faculty Bibliography

We sought to determine the diagnostic utility of additional full-length radiographs of the forearm and humerus for pediatric supracondylar humerus fractures. A pediatric orthopedic surgeon and a senior orthopedic resident individually reviewed the initial humerus, forearm, and elbow radiographs of 55 children with a supracondylar humerus fracture and recommended definitive treatment (operative vs. nonoperative) on the basis of the modified Gartland classification. Interobserver agreements for classification and the recommended treatment were highest for the elbow radiographs (weighted κ=0.92). All disagreements in the recommended treatment were in fractures classified as Gartland type I versus II fractures. Although two children (4%) had an ipsilateral distal forearm fracture, selective versus routine use of additional full-length radiographs in children with a supracondylar humerus fracture needs to be evaluated further.

BACKGROUND: The radial nerve is at risk for iatrogenic injury during placement of pins, screws, or wires around the distal humerus. Unlike adults, detailed anatomic information about the relationship of the nerve to the distal humerus is lacking in children. QUESTION/PURPOSES: This study evaluates the relationship of the radial nerve to the distal humerus in a pediatric population on conventional MRI and proposes an anatomic safe zone using easily identifiable bony landmarks on an AP elbow radiograph. METHODS: To determine the course of the radial nerve at the lateral distal humerus, we reviewed 23 elbow radiographs and MRIs of 22 children (mean age, 9 +/- 4 years; range, 3-12 years) obtained as part of their workup for various elbow conditions. We described a technique using distance ratios calculated as a percentage of the patient's own transepicondylar distance, defined as the distance measured between the apices of the medial and lateral epicondyles, on the AP elbow radiograph and the midcoronal MR image. The cross-reference tool on a Picture Archiving and Communication System was then used to identify axial MR image at the level where the transepicondylar distance was measured. On this axial image, a line was drawn connecting the medial and lateral epicondyles (the transepicondylar axis) and its midpoint was determined. The radial nerve angle was measured by a line from the radial nerve to the midpoint of the transepicondylar axis and a line along the lateral half of the transepicondylar axis. On this axial slice, the closest distance from the nerve to the underlying cortex of the distal humerus was measured. To further localize the nerve along the distal humerus, predetermined percentages of the transepicondylar distance were projected proximally from the level of the transepicondylar axis along the longitudinal axis of the humerus on the midcoronal MR image. At these designated heights, the corresponding axial MR image was identified using the cross-reference tool and the nerve was mapped in a similar fashion. We then proposed a simpler method using a best-fit line drawn along the lateral supracondylar ridge on the AP radiograph to define the safe zone for lateral pin entry. RESULTS: On axial MR images, the radial nerve was located in the anterolateral quadrant with a mean radial nerve angle of 54 degrees (range, 35 degrees -87) at 0% transepicondylar distance (23 MRIs), 41 degrees (range, 24 degrees -63 degrees ) at 50% transepicondylar distance (23 MRIs), and >/= 10 degrees at 75% transepicondylar distance (on the 13 MRIs that extended this far cephalad). The mean closest distance between the radial nerve and the underlying humeral cortex was 10 mm (range, 3-26 mm) at 0% transepicondylar distance and 7 mm (3-16 mm) at 50% transepicondylar distance. On the AP elbow radiograph, the height of the lateral supracondylar ridge, determined by a best-fit line drawn along the lateral cortex of the ridge, diverged from the most proximal extent of the ridge at a point located at 60% transepicondylar distance (range, 51%-76%). At the corresponding location on the axial MR image, the nerve was located anterolaterally with a mean radial nerve angle of 39 degrees (range, 15 degrees -61 degrees ) and a mean distance of 6 mm (range, 2-10 mm) from the underlying humerus. CONCLUSIONS: Our data suggest that percutaneous direct lateral entry Kirschner wires and half-pins can be safely inserted in the distal humerus in children along the transepicondylar axis, either at or slightly posterior to the lateral supracondylar ridge, when placed caudal to the point located where the lateral supracondylar ridge line diverges from the proximal extent of the supracondylar ridge on AP elbow radiograph.

BACKGROUND AND PURPOSE: Leg-length discrepancy (LLD) can be a sequela of slipped capital femoral epiphysis (SCFE). We tried to identify factors that affect the development of LLD following SCFE. PATIENTS AND METHOD: We evaluated 85 patients who had been treated using percutaneous screw fixation. The average age of the patients at the time of surgery was 12 (8-16) years. The relationship of LLD and various clinical and radiographic parameters was evaluated: the degree of slip, articulotrochanteric distance (ATD), and articulotrochanteric distance difference (ATDD) (healthy side minus the side with SCFE). We assessed the relationship between ATDD and LLD based on scanogram. RESULTS: The average LLD was 1.4 (0.1-3.8) cm at 6 (2-15) years postoperatively. 48 of 85 patients had an LLD of greater than 1 cm and 10 patients had an LLD of greater than 2 cm. There was a correlation between the magnitude of LLD and the severity of the slip. There was no statistically significant correlation between LLD and the stability of the slip, age, BMI, sex, or race. There was a significant correlation between LLD and ATDD. INTERPRETATION: Patients with a high degree of slip are prone to develop clinically significant LLD. Although ATDD does not give the exact LLD, it can be used as a primary measurement, which should be supplemented with scanogram in cases of clinically significant differences in length.

BACKGROUND: The purpose of this study was to determine the optimum pin configuration and the number of pins needed to stabilize the Milch type II lateral humeral condyle fractures in a pediatric bone model. METHODS: Forty synthetic pediatric humeri were sectioned through the lateral distal humerus to simulate a Milch type II lateral condyle fracture. Each fracture was stabilized with 0.062-in K-wires in 1 of 5 configurations: 2 convergent pins, 2 parallel pins, 2 divergent 30-degree pins, 2 divergent 60-degree pins, and 3 divergent pins (n=8/group). Models were tested in extension, flexion, varus, and valgus by applying a translational force through the distal fragment at 0.5 mm/sec oscillating between 5 N and 50 N for 10 cycles. For internal and external rotation, constructs were tested at 0.5 degree/sec between +/-1 Nm more than 10 cycles. The maximum force and torque values were also recorded. For bending loads, stiffness was calculated between 0.5 and 5 mm of displacement, whereas torsional stiffness was calculated between 1 degree and 10 degrees of rotation. Data for stiffness were analyzed with a 1-way analysis of variance and a 2-sample t test (P<0.05). RESULTS: Among 2-pin configurations, divergent (60 degrees) pins provided statistically greater stability than less divergent pins in torsional loading, and greater stability than parallel pins in valgus loading. Three divergent pins had statistically greater stability than all the 2-pin configurations in valgus and torsional loading, and tended to provide more secure fixation in varus loading. CONCLUSIONS: For 2-pin constructs, maximizing pin divergence at the fracture site provided greater stability in torsional loading and valgus loading. The addition of a third pin in a divergent orientation increases stability compared with 2-pin constructs in valgus, internal, and external rotation loading. CLINICAL RELEVANCE: Bicortical pins placed with maximum divergence and spread at the fracture site maximizes stability for 2-pin constructs in Milch type II lateral condyle fractures. If the stability of the fracture is questionable after 2 pins are inserted, the addition of a divergent third pin enhances the stability.

BACKGROUND: The most common position of malreduced type III supracondylar humerus (SCH) fractures is internal rotation and medial collapse of the distal fragment. The purpose of this study was to determine the effect of SCH fracture rotational deformity on stability with various pin configurations. Specifically, is the biomechanical stability lost when an SCH fracture is pinned in slight malreduction (compared with anatomical pinning) improved by adding a third pin? METHODS: Sixty-four synthetic humeri were sectioned in the mid-olecranon fossa to simulate an SCH fracture. Specimens were randomized to an anatomically reduced group or a group with 20 degrees of distal fragment internal rotation (n = 32 per group). Each was randomized to one of 4 pin configurations: 2 laterally divergent pins, 2 crossed pins, 3 laterally divergent pins, or 2 lateral with 1 medial pin (n = 8 per group). All fractures were stabilized with 1.6 mm (0.062 in) Kirschner wires. Models were tested in extension, varus, and valgus for 10 cycles between 5 N and 50 N. Internal and external rotations were tested between +/-1 Nm. Data for fragment stiffness (newtons per millimeter or newton millimeters per degree) were analyzed with a 2-way analysis of variance (p < 0.05). RESULTS: Internally rotated fractures were significantly less stable than the anatomically reduced group for external rotation, internal rotation, and varus loading regardless of pin configuration. Within the malreduced group, 3-pin configurations were more stable than 2-pin configurations in internal rotation, varus, and extension loading. Two lateral divergent pins were similar to 2 crossed pins, except in extension, where 2 lateral pins had greater stiffness. CONCLUSIONS: Construct stiffness for malreduced specimens after pinning was less than those pinned with an anatomical reduction when loaded in varus, internal rotation, and external rotation. For simulated fractures with residual internal rotation, the addition of a third Kirschner wire compared with an anatomically reduced 2-crossed-pin configuration resulted in increased stiffness of the model for all loading directions. CLINICAL RELEVANCE: Consider a 3-pin pattern, either 3 laterally divergent pins or 2 lateral pins and 1 medial pin, for SCH fractures when a less than complete anatomical reduction is obtained.

Advances in understanding age-related changes in articular cartilage, joint homeostasis, the natural healing process after cartilage injury, and improved standards for evaluation of a joint surface made the ultimate goal of cartilage repair a possibility. New strategies for enhancement of articular cartilages' limited healing potential and biologic regeneration include advances in tissue engineering and the use of electromagnetic fields. This article reviews developments in basic science and clinical research made with these emerging technologies concerning treatment of articular cartilage defects and treatment of osteoarthritis of the ankle.