Seth A. Cheatham

The effect of ultrasound frame rate on perfluorocarbon-exposed sonicated dextrose albumin microbubble size and concentration when insonifying at different flow rates, transducer frequencies, and acoustic outputs

The purpose of this article was to compare the effects of 1 and 30 Hz frame rates on perfluorocarbon-exposed sonicated dextrose albumin microbubble size and concentration in a flow cell containing either saline or blood at 37 degrees C. Microbubble size and concentration of perfluorocarbon-exposed sonicated dextrose albumin were measured after insonation at different acoustic outputs, transducer frequencies, and flow rates with the use of the two different frame rates and compared with no ultrasound exposure. At 2.0 MHz insonation frequency, microbubble concentration was significantly reduced with the use of a 30 Hz frame rate and peak negative pressures of 1.1 megaPascal (mPa). This destruction did not occur when using a lower acoustic output, a 1 Hz frame rate, or when flow rate was increased to 100 cc/min. One-hertz frame rates at 2.0 MHz resulted in a significantly larger mean microbubble size than 30 Hz or no ultrasound in both saline and blood, which was in part due to selective destruction of smaller microbubbles. These findings indicate that 30 Hz frame rates destroy perfluorocarbon-exposed sonicated dextrose albumin microbubbles only at higher diagnostic acoustic outputs. A 1 Hz frame rate prevents this destruction, especially destruction of larger (> 5.0 microns) microbubbles.

Anatomic revision ACL reconstruction.

Anterior cruciate ligament (ACL) injuries are common in the athletic population. In fact, ACL reconstruction has become one of the most common orthopedic procedures with over 100,000 being performed annually. As the number of primary ACL reconstructions continues to increase, so will the need for revision surgery. The causes of failure are numerous and multifactorial. However, understanding the exact cause of failure before undertaking a revision ACL surgery is paramount in providing the patient with a successful outcome. It is our belief that anatomic restoration of ACL anatomy in the revision setting is best accomplished using the double-bundle technique in the majority of cases. This is a technically demanding procedure that requires proper preoperative preparation. This article outlines our approach to these challenging situations.

Reverse end-to-side neurotization in a regenerating nerve.

Bypass grafting around a neuroma-in-continuity entails coapting a nerve graft above and below the injured segment using two sequential end-to-side repairs. The proximal repair is analogous to what has been classically described as an end-to-side repair; the axons from the intact nerve sprout into the end of a recipient nerve and travel distally. At the distal connection, however, axons in the graft must enter the side of the intact nerve and find their way to appropriate end organs. This process has not been well investigated. To examine this, a reverse end-to-side repair, suturing the distal end of the peroneal nerve to the side of a transected and repaired tibial nerve, was performed in 20 rats. A primary end-to-end repair of the tibial nerve was performed in 10 additional rats. Twelve weeks later, contraction forces of the gastrocnemius muscle were measured following proximal stimulation. Measurements were repeated following elimination of potential axonal pathways to identify which axons (peroneal or tibial) had achieved greater reinnervation. The results indicated that both groups of axons had achieved significant reinnervation. This study supports the idea that a reverse end-to-side repair can result in axonal invasion of an intact but regenerating nerve and achieve functional recovery.

Immediate changes in pressure pain sensitivity after thoracic spinal manipulative therapy in patients with subacromial impingement syndrome: A randomized controlled study

BACKGROUND Thoracic SMT can improve symptoms in patients with subacromial impingement syndrome. However, at this time the mechanisms of SMT are not well established. It is possible that changes in pain sensitivity may occur following SMT. OBJECTIVES To assess the immediate pain response in patients with shoulder pain following thoracic spinal manipulative therapy (SMT) using pressure pain threshold (PPT), and to assess the relationship of change in pain sensitivity to patient-rated outcomes of pain and function following treatment. DESIGN Randomized Controlled Study. METHODS Subjects with unilateral subacromial impingement syndrome (n = 45) were randomly assigned to receive treatment with thoracic SMT or sham thoracic SMT. PPT was measured at the painful shoulder (deltoid) and unaffected regions (contralateral deltoid and bilateral lower trapezius areas) immediately pre- and post-treatment. Patient-rated outcomes were pain (numeric pain rating scale - NPRS), function (Pennsylvania Shoulder Score - Penn), and global rating of change (GROC). RESULTS There were no significant differences between groups in pre-to post-treatment changes in PPT (p ≥ 0.583) nor were there significant changes in PPT within either group (p ≥ 0.372) following treatment. NPRS, Penn and GROC improved across both groups (p < 0.001), but there were no differences between the groups (p ≥ 0.574). CONCLUSION There were no differences in pressure pain sensitivity between participants receiving thoracic SMT versus sham thoracic SMT. Both groups had improved patient-rated pain and function within 24-48 h of treatment, but there was no difference in outcomes between the groups.

Anticipating problems unique to revision ACL surgery.

Anterior cruciate ligament (ACL) injuries are common in the athletic population. In fact, ACL reconstruction has become one of the most common orthopedic procedures. With the increasing number of primary ACL reconstructions being performed combined with the continued expectations of high-level athletes, revision ACL reconstruction is likely to become more frequent. Revision ACL reconstruction poses several diagnostic and technical challenges compared to primary reconstructions. The purpose of this article is to highlight problems that are unique to revision ACL reconstruction such as tunnel malposition, tunnel widening, preexisting hardware, and injuries to concomitant structures in the knee. Recognizing and avoiding these pitfalls are crucial to obtaining a successful result after revision ACL reconstruction.

Thoracic Spine Manipulation in Individuals With Subacromial Impingement Syndrome Does Not Immediately Alter Thoracic Spine Kinematics, Thoracic Excursion, or Scapular Kinematics: A Randomized Controlled Trial

STUDY DESIGN Randomized controlled trial. OBJECTIVES To determine if thoracic spinal manipulative therapy (SMT) alters thoracic kinematics, thoracic excursion, and scapular kinematics compared to a sham SMT in individuals with subacromial impingement syndrome, and also to compare changes in patient-reported outcomes between treatment groups. BACKGROUND Prior studies indicate that thoracic SMT can improve pain and disability in individuals with subacromial impingment syndrome. However, the mechanisms underlying these benefits are not well understood. METHODS Participants with shoulder impingement symptoms (n = 52) were randomly assigned to receive a single session of thoracic SMT or sham SMT. Thoracic and scapular kinematics during active arm elevation and overall thoracic excursion were measured before and after the intervention. Patient-reported outcomes measured were pain (numeric pain-rating scale), function (Penn Shoulder Score), and global rating of change. RESULTS Following the intervention, there were no significant differences in changes between groups for thoracic kinematics or excursion, scapular kinematics, and patient-reported outcomes (P>.05). Both groups showed an increase in scapular internal rotation during arm raising (mean, 0.9°; 95% confidence interval [CI]: 0.3°, 1.6°; P = .003) and lowering (0.8°; 95% CI: 0.0°, 1.5°; P = .041), as well as improved pain reported on the numeric pain-rating scale (1.2 points; 95% CI: 0.3, 1.8; P<.001) and function on the Penn Shoulder Score (9.1 points; 95% CI: 6.5, 11.7; P<.001). CONCLUSION Thoracic spine extension and excursion did not change significantly following thoracic SMT. There were small but likely not clinically meaningful changes in scapular internal rotation in both groups. Patient-reported pain and function improved in both groups; however, there were no significant differences in the changes between the SMT and the sham SMT groups. Overall, patient-reported outcomes improved in both groups without meaningful changes to thoracic or scapular motion. LEVEL OF EVIDENCE Therapy, level 1b-.

Effect of blood and microbubble oxygen and nitrogen content on perfluorocarbon-filled dextrose albumin microbubble size and efficacy: In vitro and in vivo studies

We hypothesized, on the basis of in vitro observations, that a higher oxygen partial pressure within perfluorocarbon-containing microbubbles (PCMB) would enhance inward nitrogen diffusion after venous injection, leading to improved myocardial contrast. The in vitro studies measured PCMB size and concentration after injection into arterial blood that was obtained during inhalation of either room air or 100% oxygen. We then compared the myocardial contrast produced from PCMB sonicated in the presence of either a nitrogen-free environment (100% oxygen) or room air in three closed chest dogs. PCMB exposed to oxygenated blood in vitro were significantly smaller after insonation than PCMB exposed to arterial blood obtained during room air inhalation, confirming the important role of dissolved nitrogen in stabilizing PCMB size. In vivo studies demonstrated that intravenous PCMB sonicated with 100% oxygen produced significantly greater anterior and posterior myocardial contrast than PCMB sonicated in the presence of room air.

Complete avulsion of the patellar tendon from the tibial tubercle in an adult without predisposing factors.

IntroductionAcute traumatic patellar tendon rupture in the adult pop-ulation usually occurs in younger patients (\40 years old)during athletic activities in which the quadriceps contractseccentrically when the knee is flexed. Systemic disease andsteroid use may predispose to rupture [1, 2], which in thevast majority of cases involves the tendon’s origin at theinferior pole of the patella [2, 3]. Ruptures of the distalpatellar tendon are extremely rare. Only two cases ofpartial rupture of the distal insertion of the patellar tendonhave been reported, occurring in athletes [4].To the authors’ best knowledge, there have been noreports of complete avulsion of the patellar tendon of thetibial tubercle in the adult. We present a very atypical caseof complete distal avulsion of the patellar tendon in anotherwise healthy patient in the absence of predisposingfactors. The patient was informed that data regarding hercase would be submitted for publication.Case reportA 52-year-old female presented to our institution com-plaining of significant pain in her right knee. She hadsustained a ground level fall directly on the anterior surfaceof her right knee 3 days before presentation. She was ini-tially seen at an outside Emergency Room where she wastold that the radiographs were negative for a fracture. Shewas subsequently placed in a knee immobilizer, givencrutches to ambulate and told to follow up with an ortho-pedic surgeon. Her past medical history is significant forhypertension and anxiety. The patient denied any priortrauma, any pre-existing symptoms or history of systemicdisease, corticosteroid or quinolone use. On physical exam,there was significant swelling and ecchymosis present.There was tenderness to palpation directly over the tibialtubercle. The patient was unable to perform a straight-legraise. There was a palpable defect along the inferiorinsertion of the patellar tendon. Plain radiographs demon-strated patella alta with no identifiable fracture (Fig. 1a, b).An MRI scan was performed that revealed a completeavulsion of the distal patellar tendon from the tibialtubercle insertion with 6 cm of proximal retraction(Fig. 2). The patient was taken to the operating room, andafter evacuating out the traumatic hematoma, the patellartendon was easily identified (Fig. 3a, b). Two no. 5 Tycronsutures were then placed through the patellar tendon andrun distally using a locking Krackow stitch (Fig. 3c). Thetibial tubercle base was then roughened up using a 3-mmbur to create a bleeding base. Three drill holes were thenplaced through the tibial tubercle. A single G2 Mitekanchor was then placed slightly more proximal to whereour tendon was going to attach distally. With the knee infull extension, the patellar tendon was then tied back downto the tibial tubercle over bone tunnels. The limbs of the G2Mitek suture anchor were then secured to reinforce ourrepair and create a broader footprint along the tibialtubercle. Postoperatively, the patient was placed in a hin-ged brace locked in full extension. She was allowed to bearweight as tolerated. Physical therapy was initiated after6 weeks to work on a progressive range of motion andstrengthening. Two and a half months after the procedure,

Arthroscopic Technique for the Evaluation and Treatment of Posterior Shoulder Instability

Posterior instability is becoming an increasingly recognized problem with todays contact athletes. Although not as common as anterior Bankart lesions, posterior capsulolabral pathology can lead to significant instability and pain. Open posterior repair is difficult and results in the literature have been inconsistent. However, there is recent evidence to support arthroscopic repair with capsular placation as a promising solution. Our technique for arthroscopic posterior capsulolabral repair will be reviewed with emphasis on the key aspects for a successful outcome.

Performance-Enhancing Drugs and Today's Athlete : A Growing Concern

The use of anabolic steroids in professional athletes has been a concern for a long time; however, the rise in use by younger athletes is especially troubling. Physicianguided education is vital to the creation of an effective intervention program.