Brian Park

Selection and development of preclinical models in fracture-healing research.

Animal fracture models have been extensively applied to preclinical research as a platform to identify and characterize normal and abnormal physiological processes and to develop specific maneuvers that alter the biology and biomechanics being examined. The choice of animal model employed in a study bears a direct relationship to the specific intervention being analyzed. The animal models employed should be described clearly, control-group data should be established, and reproducibility should be defined from experiment to experiment and from institution to institution so that quantitative and qualitative outcomes can be reliably compared and contrasted to other related studies.

Automated Delineation of Dermal–Epidermal Junction in Reflectance Confocal Microscopy Image Stacks of Human Skin

Reflectance confocal microscopy (RCM) images skin noninvasively, with optical sectioning and nuclear-level resolution comparable with that of pathology. On the basis of the assessment of the dermal-epidermal junction (DEJ) and morphologic features in its vicinity, skin cancer can be diagnosed in vivo with high sensitivity and specificity. However, the current visual, qualitative approach for reading images leads to subjective variability in diagnosis. We hypothesize that machine learning-based algorithms may enable a more quantitative, objective approach. Testing and validation were performed with two algorithms that can automatically delineate the DEJ in RCM stacks of normal human skin. The test set was composed of 15 fair- and 15 dark-skin stacks (30 subjects) with expert labelings. In dark skin, in which the contrast is high owing to melanin, the algorithm produced an average error of 7.9±6.4 μm. In fair skin, the algorithm delineated the DEJ as a transition zone, with average error of 8.3±5.8 μm for the epidermis-to-transition zone boundary and 7.6±5.6 μm for the transition zone-to-dermis. Our results suggest that automated algorithms may quantitatively guide the delineation of the DEJ, to assist in objective reading of RCM images. Further development of such algorithms may guide assessment of abnormal morphological features at the DEJ.

Acute Management of Shoulder Dislocations

The shoulder joint has the greatest range of motion of any joint in the body. However, it relies on soft-tissue restraints, including the capsule, ligaments, and musculature, for stability. Therefore, this joint is at the highest risk for dislocation. Thorough knowledge of the shoulder’s anatomy as well as classification of dislocations, anesthetic techniques, and reduction maneuvers is crucial for early management of acute shoulder dislocation. Given the lack of comparative studies on various reduction techniques, the choice of technique is based on physician preference. The orthopaedic surgeon must be well versed in several reduction methods and ascertain the best technique for each patient.

Revision of Failed Hip Resurfacing and Large Metal-on-Metal Total Hip Arthroplasty Using Dual-Mobility Components.

Revision of metal-on-metal (MoM) total hip arthroplasty (THA) or hip resurfacing is associated with high complication rates. The authors propose dual-mobility components as a surgical option and present short- to mid-term results of MoM hips revised with dual-mobility components. Eighteen consecutive hips that underwent revision of MoM THA or hip resurfacing using dual-mobility components were identified. At final follow-up (mean, 17.5 months), the visual analog scale, modified Harris Hip Score, and SF-12 scores had all improved (P<.05, P<.01, and P<.05, respectively). There were no dislocations or other complications. Revision of failed MoM THA or hip resurfacing using a dual-mobility device is an effective strategy.

Arthroscopic Treatment of Labral Tears and Concurrent Avascular Necrosis of the Femoral Head in Young Adults

Avascular necrosis (AVN) of the femoral head is a progressive disease affecting young adults that results in collapse of the femoral head and subsequent degenerative joint disease. Although precollapse stages of AVN can be successfully treated with core decompression, making the diagnosis is often difficult given alternative sources of hip pain in this age group. We propose that arthroscopic-assisted core decompression of the femoral head offers an effective method of addressing AVN of the femoral head as well as coexistent hip disorders in the same operation. This article describes in detail the technique used to perform an arthroscopic-assisted core decompression of the femoral head, and a companion video demonstrating the procedure is included. Our experience suggests that arthroscopic-assisted core decompression can be used as an alternative to open core decompression, while simultaneously addressing other sources of hip pain, with successful outcomes.

Anatomic variant of the inferior lateral cutaneous branch of the radial nerve during the posterior approach to the humerus: a case report

Iatrogenic injury during the posterior approach to the humerus during operative fixation is not an uncommon occurrence. A comprehensive understanding of the normal anatomy and its variants is of paramount importance in order to avoid such injury. Typically, the inferior lateral cutaneous branch of the radial nerve originates towards the distal end of the humerus at the inferior portion of the spiral groove. Here, we report an important variant of this nerve, which originated significantly more proximal than expected, further emphasizing the importance of identification, dissection and protection of the radial nerve and its major branches.

Performance of an automated renal segmentation algorithm based on morphological erosion and connectivity

The precision, accuracy, and efficiency of a novel semi-automated segmentation technique for VIBE MRI sequences was analyzed using clinical datasets. Two observers performed whole-kidney segmentation using EdgeWave software based on constrained morphological growth, with average inter-observer disagreement of 2.7% for whole kidney volume, 2.1% for cortex, and 4.1% for medulla. Ground truths were prepared by constructing ROI on individual slices, revealing errors of 2.8%, 3.1%, and 3.6%, respectfully. It took approximately 7 minutes to perform one segmentation. These improvements over our existing graph-cuts segmentation technique make kidney volumetry a reality in many clinical applications.

Reduction of anterior glenohumeral dislocations: a new closed reduction technique

ABSTRACT Objective: A new closed reduction technique for anterior glenohumeral dislocations and tuberosity fracture dislocations is introduced. Methods: Forty-one consecutive patients with an acute anterior glenohumeral dislocation or tuberosity fracture dislocation underwent closed reduction by an orthopaedic surgeon employing this new method. Results: Closed reduction was successful in 88% of patients using the reduction maneuver. Associated fracture with glenohumeral dislocation did not influence the success rate of the reduction maneuver. An assistant was needed in 15% of cases. No complications related to the reduction maneuver were noted amongst the cohort. Conclusion: This novel reduction technique is safe demonstrating excellent success rates both for anterior shoulder dislocations and tuberosity fracture-dislocations.

Low dose computed tomography pulmonary angiography protocol for imaging pregnant patients: Can dose reduction be achieved without reducing image quality?

OBJECTIVE To assess the effect of low dose computed tomography pulmonary angiography (CTPA) on radiation dose in pregnant patients. MATERIALS AND METHODS An old CTPA protocol for pregnant patients was compared to a new protocol. Protocol changes included: decreased kVp; increased contrast injection rate; imaging after shallow inspiration. Patients undergoing CTPA before (phase 1 group) or after (phase 2 group) the protocol change, were assessed. RESULTS Effective dose was lower in the phase 2 group (0.95 v 1.66 mSv; p<0.001). Quantitative noise was lower in the phase 1 group (p<0.001). CONCLUSION Low dose CTPA tailored for pregnancy reduces dose in pregnant patients.

Displaced Insufficiency Femoral Neck Stress Fracture in the Setting of Ochronosis

Alkaptonuria is a hereditary disorder of homogentisic acid metabolism. It is usually inherited in an autosomal recessive manner, although there have been reports of autosomal dominant inheritance1. In alkaptonuria, a defect in the gene that encodes homogentisic acid oxidase leads to an accumulation of homogentisic acid in the body1-4. This leads to the polymerization of homogentisic acid, which is exhibited as blue-black discoloration of various connective tissues, including hyaline cartilage. The prevalence of alkaptonuria is between one in 250,000 and one in one million people. A prevalence as high as one in 19,000 has been found in people of Slovenian and Dominican descent1,4-6. The disease is typically asymptomatic until the third or fourth decade of life. Clinically, it manifests as dark pigmented urine, abnormal pigmentation of the eyes and the ears, spondylosis, and degenerative arthritis throughout the body1-4. The orthopaedic manifestation of this disease is termed “ochronosis.” Ochronosis is a noninflammatory degenerative arthritis that results from the accumulation of homogentisic acid deposits in the joints. The knees, hips, shoulders, and spine are the most commonly affected areas1-4. Histopathologically, brown-black pigmentation occurs in the extracellular matrix of hyaline cartilage. In osteoarthritis, the hyaline cartilage appears as concentric layers of fibrillation; in ochronosis, the hyaline cartilage becomes fragmented with deep clefts that propagate toward the subchondral bone6. There is no known direct association between ochronosis and femoral neck stress fractures. To our knowledge, there has been only indirect mention of a femoral neck stress fracture in a single case report in the anesthesiology literature7. We present a case of an insufficiency femoral neck stress fracture in a patient with previously undiagnosed asymptomatic ochronosis. The patient was informed that …