Publications by authors named "Maxwell Modrak"

2 Publications

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Modification and application of the proximal humerus ossification system to adolescent idiopathic scoliosis patients.

Spine Deform 2021 May 3. Epub 2021 May 3.

Division of Orthopedics, Texas Children's Hospital, Department of Orthopedics, Baylor College of Medicine, Houston, TX, 77030, USA.

Purpose: We have previously demonstrated that proximal humeral ossification patterns are reliable for assessing peak height velocity in growing patients. Here, we sought to modify the system by including medial physeal closure and evaluate whether this system combined with the Cobb angle correlates with progression to surgery in patients with adolescent idiopathic scoliosis.

Methods: We reviewed 616 radiographs from 79 children in a historical collection to integrate closure of the medial physis into novel stages 3A and 3B. We then analyzed radiographs from the initial presentation of 202 patients with adolescent idiopathic scoliosis who had either undergone surgery or completed monitoring at skeletal maturity. Summary statistics for the percentage of patients who progressed to the surgical range were calculated for each category of humerus and Cobb angle.

Results: The intra-observer and inter-observer ICC for assessment of the medial physis was 0.6 and 0.8, respectively. Only 3.4% of radiographs were unable to be assessed for medial humerus closure. The medial humerus physis begins to close about 1 year prior to the lateral physis and patients with a closing medial physis, but an open lateral physis were found to be the closest to PHV (0.7 years). Stratifying patients by Cobb angle and modified humerus stage yield categories with low and high risks of progression to the surgical range.

Conclusion: The medial humerus can be accurately evaluated and integrated into a new modified proximal humerus ossification system. Patients with humerus stage 3A or below have a higher rate of progression to the surgical range than those with humerus stage 3B or above.
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May 2021

Pharmacological Attenuation of Electrical Effects in a Model of Compression Neuropathy.

J Bone Joint Surg Am 2019 Mar;101(6):523-530

Department of Orthopaedics and Rehabilitation, Center for Orthopaedic Research and Translational Science, The Pennsylvania State University College of Medicine, Milton S. Hershey Medical Center, Hershey, Pennsylvania.

Background: Peripheral nerve compression and entrapment can be debilitating. Using a validated animal model of peripheral nerve compression, we examined the utility of 2 drugs approved for other uses in humans, 4-aminopyridine (4-AP) and erythropoietin (EPO), as treatments for surgically induced ischemia and as adjuvants to surgical decompression.

Methods: Peripheral nerve compression was induced in wild-type mice by placing an inert silicone sleeve around the sciatic nerve. Decompression surgery was performed at 6 weeks with mice receiving 4-AP, EPO, or saline solution either during and after compression or only after decompression. A nerve conduction study and morphometric analyses were performed to compare the extent of the injury and the efficacy of the therapies, and the findings were subjected to statistical analysis.

Results: During peripheral nerve compression, there was a progressive decline in nerve conduction velocity compared with that in sham-treatment animals, in which nerve conduction velocity remained normal (∼55 m/s). Mice treated with 4-AP or EPO during the compression phase had significantly smaller declines in nerve conduction velocity and increased plateau nerve conduction velocities compared with untreated controls (animals that received saline solution). Histomorphometric analyses of newly decompressed nerves (i.e., nerves that underwent decompression on the day that the mouse was sacrificed) revealed that both treated groups had significantly greater proportions of large (>5-µm) axons than the untreated controls. Following surgical decompression, all animals recovered to a normal baseline nerve conduction velocity by day 15; however, treatment significantly accelerated improvement (in both the 4-AP and the EPO group), even when it was only started after decompression. Histomorphometric analyses at 7 and 15 days following surgical decompression revealed significantly increased myelin thickness and significantly greater proportions of large axons among the treated animals.

Conclusions: Both the 4-AP and the EPO-treated group demonstrated improvements in tissue architectural and electrodiagnostic measurements, both during and after peripheral nerve compression, compared with untreated mice.

Clinical Relevance: Peripheral nerve decompression is one of the most commonly performed procedures in orthopaedic surgery. We believe that there is reason for some optimism about the translation of our findings to the clinical setting. Our findings in this murine model suggest that 4-AP and EPO may lessen the effects of nerve entrapment and that the use of these agents after decompression may speed and perhaps otherwise optimize recovery after surgery.
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March 2019