Carpal Tunnel Release With Ultrasound Guidance: Intermediate-Term Clinical Outcomes and Magnetic Resonance Imaging Findings

Purpose

The purpose of this study was to report intermediate-term outcomes following carpal tunnel release using ultrasound guidance and wide-awake local anesthesia no tourniquet, including a subset of patients with preoperative and postoperative magnetic resonance imaging (MRI).

Methods

In this observational study, patients with carpal tunnel syndrome were treated with carpal tunnel release using ultrasound guidance and wide-awake local anesthesia no tourniquet in a procedure room at a single center. Main outcomes were complications; return to activity and work at 2 weeks; Quick Disabilities of the Arm, Shoulder, and Hand and Boston Carpal Tunnel Questionnaire scores through 6 months; and postoperative morphological changes of the transverse carpal ligament, median nerve, and carpal tunnel evaluated using MRI.

Results

No complications were reported among 65 patients (68% women, 96 wrists). By 2 weeks, 97% of patients returned to normal activity and 100% returned to work. Statistically significant improvements in Boston Carpal Tunnel Questionnaire symptom severity scale, Boston Carpal Tunnel Questionnaire functional status scale, and Quick Disabilities of the Arm, Shoulder, and Hand scores occurred by the 2-week follow-up interval and persisted at 6 months (all P < .001). Pre- and postoperative MRI scans were available for 13 patients (17 wrists) at the 3-month mean follow-up. Complete transverse carpal ligament transection was documented in all wrists. Key MRI findings included a 22% increase in carpal tunnel cross-sectional area at the hamate (P < .001), a 52% increase in median nerve cross-sectional area at the hamate (P < .001), an 18% reduction in median nerve signal intensity (P = .002), a 38% reduction in the flattening ratio of the median nerve at the hamate (P < .001), a 33% reduction in the flattening ratio of the median nerve at the pisiform (P < .001), a 20% reduction in the flattening ratio of the carpal tunnel at the hamate (P < .001), and a palmar shift of the median nerve relative to the hamate in all cases.

Conclusions

Carpal tunnel release using ultrasound guidance using wide-awake local anesthesia no tourniquet in a procedure room setting was safe, effective, and resulted in morphological changes that were consistent with carpal tunnel decompression as demonstrated by MRI.

Type of study/level of evidence

Therapeutic IV.

Innovation for Orthopaedic Surgeons

Entrepreneurship and innovation are cornerstones of the economy and move healthcare forward. Most physicians have little experience or knowledge in developing and commercializing novel concepts and ideas. It is important to focus on structured thinking concepts, fundraising, intellectual property, FDA regulations, and initial incorporation and teambuilding strategies. There are various aspects of creating ideas and moving them from notes scribbled on a napkin to a product or service, which can then be integrated into the economic fabric of the healthcare system. Surgeon founders and innovators can then share key aspects any surgeon should consider when becoming an entrepreneur.

Chronic Exertional Compartment Syndrome Caused by Functional Venous Outflow Obstruction

OBJECTIVE

Investigate the theory that chronic exertional compartment syndrome (CECS) results from venous outflow obstruction due to functional muscular compression. Chronic exertional compartment syndrome occurs when increased pressure within a muscle compartment produces pain and/or neurologic symptoms. The exact etiology of CECS is unknown, leading to inconsistent diagnostic and treatment plans.

STUDY DESIGN

Retrospective case series.

SETTING

Private practice and sports medicine.

PATIENTS

Two hundred eighty-four patients with exercise-induced lower leg pain. Twenty-two patients lost to follow-up.

INTERVENTIONS

Leg vasculature was evaluated using stress computed tomography angiography (CTA) and MVP Flex to identify areas of functional venous compression. All patients then underwent targeted botulinum toxin treatment. Posttreatment follow-up imaging was performed using stress CTA in 197 patients.

MAIN OUTCOME MEASURES

Presence of functional venous compression on stress CTA. Symptom reduction and normalization of venous flow after targeted botulinum toxin injections.

RESULTS

Baseline imaging demonstrated CECS and functional venous obstruction with replication of symptoms in 260 of 284 patients [91.5% ± 3.2% (95% CI)]. Four weeks after treatment, 227 of 284 patients [79.9% ± 4.7% (95% CI)] described reduced/resolved symptoms with activity. One hundred fifty-five of the 197 patients [78.7% ± 5.7% (95% CI)] reimaged with stress CTA demonstrated resolved/reduced venous outflow obstruction. Twenty-two patients were lost to follow-up, and 35 patients had persistent symptoms.

CONCLUSION

Chronic exertional compartment syndrome results from venous outflow obstruction due to functional muscular compression. Understanding the cause of CECS will allow the development of more precise and successful treatment plans. Based on our findings, treatment should be directed at the sites of venous compression.

Nonsurgical treatment of cystic adventitial disease of the popliteal artery caused by functional popliteal artery entrapment syndrome

Lower extremity claudication in young men can be caused by popliteal artery entrapment and vascular pathology. The case reported here describes a young male wrestler who presented with unilateral calf pain with activity. Imaging studies at rest demonstrated cystic adventitial disease of the popliteal artery. Stress imaging showed severe functional popliteal artery entrapment. This patient was treated with an imaging-guided botulinum toxin injection of the muscles at the site of arterial compression. The patient was asymptomatic 6 weeks after treatment. Repeat stress imaging demonstrated complete resolution of the entrapment and nearly complete resolution of the popliteal artery cystic adventitial disease.

MRI detection of forearm soft tissue injuries with radial head fractures

BACKGROUND

This study aims to evaluate the incidence of forearm soft tissue abnormalities associated with radial head fracture severity based on the Mason classification system.

METHODS

Eighteen patients (age 18-45 years) were prospectively evaluated with elbow radiographs and magnetic resonance imaging (MRI) following longitudinal forearm trauma. MRI was performed within 10 days of the initial injury. Radiographs and MR images were evaluated in a blinded fashion by two musculoskeletal radiologists.

RESULTS

Thirteen of 18 patients presented with Mason type I radial head fractures. In all patients with Mason type I fractures, the interosseous membrane (IOM) was intact. Two patients had Mason type II fractures with associated partial and compete tearing of the IOM and three patients had Mason type III fractures with complete tearing of the IOM. Edema was noted in the pronator quadratus in six of 13 type I injuries and seen in all type II and III injuries. No structural forearm soft tissue abnormalities were present in patients with Mason type I injuries. The presence of edema within the pronator quadratus correlated with distal forearm pain.

CONCLUSIONS

The severity of radial head fracture correlates with longitudinal forearm injury evidenced by the presence of IOM tearing. The findings suggest patients with Mason type II or III fractures of the radial head should undergo further evaluation of the forearm for associated soft tissue injuries. Edema within the pronator quadratus was present following forearm trauma regardless of the severity of fracture and was related to symptomatic forearm pain.

Rotator cuff tears: association with acromion angulation on MRI

OBJECTIVE

Using magnetic resonance imaging (MRI), evaluate the correlation of acromion angulation with thickening of the coracoacromial ligament (CAL) and narrowing of the subacromial space resulting in impingement upon the rotator cuff tendons.

MATERIALS AND METHODS

Eighty-nine shoulder MRI studies performed on a 3T scanner were retrospectively analyzed by two blinded independent reviewers. Measurements of the acromion angle (delta angle), CAL thickness and distance between the CAL and humeral head were obtained. The data were categorized into two groups, delta angle less that and greater than 7.5°. The presence or absence of full thickness (FT) or near full thickness (NFT) rotator cuff tears was noted.

RESULTS

In group 1, the acromion angle varied from -6.8 to 6.8° (1.7±3.5°) with a CAL thickness of 0.91±0.20 mm and a subacromial distance of 6.47±0.88 mm. Group 2 acromion angle varied from 7.6° to 46.8° (18.0°±8.1°) with a CAL of 1.77±0.51 mm and a subacromial distance of 4.52±0.82 mm. The difference in CAL thickness and subacromial distance were significantly different between the two groups (P<.001). In Group 1, 3 out of 51 patients had a FT or NFT tear of the rotator cuff compared to 20 out of 38 in Group 2 (P<.001). There was no significant interobserver variability.

CONCLUSION

Steep acromion angulation is associated with CAL thickening and narrowing of the subacromial space. Patients with a steep acromion angle had a statistically increased incidence of rotator cuff tears.

Impaired contractile reserve in severe mitral valve regurgitation with a preserved ejection fraction

BACKGROUND

Impaired contractile reserve in chronic MR results from load-independent, myocyte contractile abnormalities.

AIMS

Investigate the mechanisms of contractile dysfunction in chronic mitral valve regurgitation (MR).

METHODS

Mild MR was produced in eight dogs followed by pacing induced left ventricular (LV) dilatation over eight months. In-vivo LV dP/dt was measured at several pacing rates. Contractile function was measured in isolated LV trabeculae and myocytes at several stimulation rates and during changes in extracellular [Ca2+]. Identical studies were performed with six control dogs.

RESULTS

Chronic MR resulted in a preserved ejection fraction with decreased dP/dt (p<0.01). LV trabeculae demonstrated significantly lower developed force and a negative force-frequency relation with chronic MR (p<0.05). Myocytes exhibited a negative shortening-frequency relationship in both groups with a greater decline with chronic MR (p<0.001) paralleled by decreases in peak [Ca2+](i) transients. Increases in extracellular [Ca2+] abrogated the defects in force generation in trabeculae from animals with chronic MR.

CONCLUSION

Even with a preserved EF, chronic severe MR results in a significant reduction in intrinsic contractile function and reserve. Functional impairment was load-independent reflecting a predominant defect in calcium cycling rather than impaired peak force generating capacity due to myofibrillar attenuation.

Nondisplaced elbow fractures: A commonly occurring and difficult diagnosis

PURPOSE

Determine the sensitivity and specificity of radiography in identifying nondisplaced elbow fractures after trauma. Our hypothesis is that nondisplaced fractures occur commonly following impact injuries and are difficult to diagnose with plain film imaging.

METHODS

An in vitro double-blinded study of 16 cadaver arms was designed, simulating axial forearm trauma. Following injury, anteroposterior and lateral radiographs were obtained. Each specimen was dissected, and the injury described. A musculoskeletal radiologist, blinded to dissection results, examined the radiographs.

RESULTS

Dissection revealed 39 fractures of 96 sites examined. A total of 14 fractures were nondisplaced, 7 involving the coronoid process. Radiographs identified 27 fractures. Of the 12 missed fractures, 11 were nondisplaced. Radiographic diagnosis of nondisplaced elbow fractures demonstrated a 21% sensitivity, 95% specificity, 50% positive predictive value, and 83% negative predictive value.

CONCLUSIONS

Radiography for nondisplaced elbow fractures demonstrated limited success. Additional imaging studies may be required in suspected elbow injuries with initial negative radiographs.

Forearm interosseous membrane trauma: MRI diagnostic criteria and injury patterns

OBJECTIVE

Define criteria for interosseous membrane (IOM) injury diagnosis using MRI, and characterize patterns of IOM disruption following forearm trauma. Our hypothesis is that most IOM injuries occur along the ulnar insertion, and MRI should be obtained following forearm trauma to assess IOM competency.

DESIGN

Sixteen cadaver forearms were subjected to longitudinal impact trauma. Prior to and following injury, MR images were examined by a board-certified musculoskeletal radiologist using pre-defined criteria for determining IOM integrity. Each specimen was dissected and the viability/pattern of injury examined. The MRI and dissection results were compared using a double-blinded methodology.

RESULTS

Eight of the 16 specimens demonstrated IOM trauma. Seven specimens demonstrated complete IOM disruption from the ulnar insertion, and one revealed a mid-substance tear with intact origin and insertion. The dorsal oblique bundle was disrupted in four specimens. MRI analysis identified IOM injury in seven of the eight forearms. The injury location was correctly identified in six specimens when compared to dissection observations. MRI determination of IOM injury demonstrated a positive predictive value of 100%, a negative predictive value of 89%, a sensitivity of 87.5% and a specificity of 100%.

CONCLUSION

Our findings demonstrate the accuracy of MRI in identifying IOM disruption, and its ability to localize specific injuries in a clinically relevant model of forearm trauma. The injury patterns demonstrated most lesions occurred along the IOM's ulnar insertion, and in half of the injured specimens there was concomitant dorsal oblique bundle disruption.

Subvalvular Alterations Promote Increased Mitral Valve Regurgitation in Progressive Dilated Cardiomyopathy

BACKGROUND

Alterations in transmitral pressure, valve structure, subvalvular geometry, and abnormal myocardial function have all been implicated in the pathophysiology of functional/progressive mitral valve regurgitation (MR). In this study, we hypothesized that a relatively small structural lesion to the mitral valve apparatus predisposes to severe MR in the setting of progressive left ventricular dilation. While examining this hypothesis, an additional purpose of this study was to determine the extent of papillary muscle (PM) distortion and mitral annular dilation with increasing MR resulting from progressive dilated cardiomyopathy.

METHODS AND RESULTS

Mild MR was produced via a limited, fixed structural lesion to the mitral valve apparatus of 8 dogs (20 to 22 kg). Incremental tachypacing induced left ventricular dilation over an 8-month period. The pacer was deactivated and the dogs followed for an additional 6 weeks. Echocardiographic measurements demonstrated significant cardiac remodeling (left ventricular end diastolic diameter) and MR progression with a 54% increase in left ventricular end diastolic diameter and a 44% increase in MR jet area (P < .05). Tachypacing induced decreases in left ventricular ejection fraction recovered nearly to baseline levels by 6 weeks after pacing cessation. Nevertheless, left ventricular dilation persisted and MR remained severe after pacing cessation. There was a significant increase in the short axis PM segment length and PM angular separation from baseline (6.28 +/- 0.83 versus 4.02 +/- 0.56 cm and 99.7 +/- 2.6 versus 90.1 +/- 3.2 deg, respectively, P < .05) with no change in mitral annulus circumference (8.71 +/- 0.70 versus 8.15 +/- 0.35 cm, P = NS).

CONCLUSION

Progressive MR severity in nonischemic dilated cardiomyopathy resulted from changes in left ventricular shape and altered papillary muscle geometries and does not require mitral annulus dilation or a reduced left ventricular ejection fraction.

Forearm interosseous membrane imaging and anatomy

OBJECTIVE

To determine the regional thickness variation of the interosseous membrane (IOM) along the forearm and validate magnetic resonance imaging of the IOM with laser micrometry.

DESIGN AND PATIENTS

Axial thickness measurements of 12 cadaver forearms were obtained using magnetic resonance imaging (MRI) at radial, central, and ulnar locations. The specimens were dissected, and IOM thickness measured using a laser micrometer. MRI and laser measurements of the main and oblique IOM bundles were compared. An axial thickness profile was plotted versus forearm length, and radial, central, and ulnar positions were compared.

RESULTS

The main bundle thickness was 2.18+/-0.20 mm using laser micrometry, which was not significantly different from MRI measurements (1.86+/-0.25 mm, p=0.11, power = 0.84). The dorsal oblique bundle thickness was not significantly different between measurement methods (2.93+/-0.77 mm and 3.30+/-1.64 mm using laser micrometry and MRI respectively, p=0.75, power = 0.04). Both methods demonstrated a progressive increase in thickness proximally within the forearm. MRI measurements demonstrated a significantly greater thickness increase in the radial location compared to the central location (slope = 2.26 and 1.05, r(2)=0.31 and 0.12 respectively, p<0.05). The ulnar slope was not significantly different from zero ( r(2)=0.02, p>0.05).

CONCLUSION

Our findings describe the varying IOM anatomy using MRI, and determined the location of the clinically important IOM fiber bundles. This study confirms the accuracy of MR imaging of the IOM by comparison with a laser micrometer, and demonstrates the thickness variation along the forearm. This information may be used to identify changes in IOM anatomy with both acute IOM injury and chronic fiber attenuation.

Forearm and elbow injury: the influence of rotational position

BACKGROUND

The purpose of this study was to develop an axial loading forearm fracture model and to determine the influence of forearm rotation on the fracture pattern.

METHODS

Twenty-six cadaveric arms were thawed in saline solution. Pressure-sensitive film was sealed and was placed through a lateral arthrotomy into the radiocapitellar joint. The arm was potted at the proximal part of the humerus with the elbow in extension. Rotational range of motion was measured with use of a goniometer starting from a supinated position (0 degrees ). Specimens were placed in a vertical position at various angles of forearm rotation, and a 27-kg mass was raised to 90 cm and was dropped onto the distal part of the radius. The pressure film was removed and was analyzed to determine the radiocapitellar joint contact area following impact. Each arm was dissected, and the injury pattern was assessed.

RESULTS

Both-bone forearm fractures (proximal radial fractures with concomitant distal ulnar fractures) occurred at 5 degrees +/- 2.6 degrees of rotation, isolated radial head fractures occurred at 44.4 degrees +/- 5.2 degrees of rotation, and Essex-Lopresti fractures (radial head fractures with tearing of the interosseous membrane) occurred at 70 degrees +/- 25.2 degrees of rotation. The distribution of Essex-Lopresti and radial head fractures was significantly different at a cutpoint of 54 degrees of forearm rotation (p = 0.009), and the distribution of radial head fractures and both-bone forearm fractures was significantly different at a cutpoint of 10 degrees of forearm rotation (p = 0.001). The percent contact area of the radial head varied with the injury pattern (p = 0.029). Marginal radial head fractures occurred at 46.7 degrees +/- 6.6 degrees of rotation with a contact area of 30.9% +/- 8.6%, while comminuted radial head fractures occurred at 74.4 degrees +/- 27.2 degrees of rotation with a contact area of 53.9% +/- 8.3%.

CONCLUSION

The amount of forearm rotation at the time of axial load impact directly influenced the injury pattern. Furthermore, the radial head contact area and the fracture severity increased in pronation compared with supination.

Biochemical composition and histologic structure of the forearm interosseous membrane

PURPOSE

The purpose of this study was to determine the structure and composition of the forearm interosseous membrane (IOM).

METHODS

The IOM of 12 cadaver forearms was fixed in formalin. After fixation 5 individual IOM fiber bundles per arm were separated by dissection, excised, and processed with hematoxylin-eosin, trichrome, and Verhoff-vanGeison stains. Nine additional fresh forearms were dissected and 5 IOM fiber bundles per arm were analyzed using the hydroxyproline assay. Bundles were evaluated at ulnar, central, and radial locations.

RESULTS

Histologic analysis of the IOM bundles obtained from the 12 fixed forearms showed an abundance of collagen in the main bundle central location (84% +/- 7.8%). A progressive increase in collagen was noted from distal to proximal bundles (r =.72). The hydroxyproline assay of collagen content of the main IOM bundle's central location from the 9 additional fresh forearms was 99.3% +/- 16.5%. There was no difference between bundles or location (power = 0.25 and 0.46).

CONCLUSIONS

We found that the IOM possesses a large collagen content arranged in fibrillar structures surrounded by elastin. Collagen was abundant in the proximal bundles and decreased in the distal bundles.

Mechanics of the antebrachial interosseous membrane: response to shearing forces

The interosseous membrane functions to maintain the structural integrity of the forearm; however, the age-related mechanical properties of the intact membrane are incompletely defined. The purpose of this study is to quantify the mechanical properties of the interosseous membrane by applying a quasi-equilibrium shearing force between the radius and ulna. A 5-cm section of the central (main and accessory bundles) fiber from 11 (5 male and 6 female) fresh-frozen cadaver arms (age, 74 +/- 6.9 years) was isolated with the radial and ulnar attachments, measured, and positioned into the testing apparatus. A shear force was applied at 12.7 mm/min to produce a quasi-equilibrium state, and the applied force and elongation were monitored. The average ultimate force, ultimate strength, and elastic modulus were 1101 +/- 191 N, 13.98 +/- 4.85 MPa, and 135.29 +/- 41.57 MPa, respectively. Age-related changes were also noted with an increase in thickness by 0.056 mm per year of age and a decrease in fiber stiffness of 4.78 MPa/yr. The age-related mechanical properties of the intact interosseous membrane are necessary for modeling forearm stability in normal and pathologic conditions. This information is required for analysis of repair or reconstructive procedures.

Interosseous membrane anatomy and functional mechanics

Longitudinal forearm stability is maintained through the interaction of several anatomic structures. One such structure, the interosseous membrane, is a fibrous tissue with an oblique orientation from the radius to the ulna. The membrane maintains the interosseous space between the radius and ulna through forearm rotation and actively transfers forces from the radius to the ulna. The interosseous membrane's unique functional capabilities result from its anatomic and histologic organization, which produces a stiff structure with elastic properties capable of maintaining large loads. The interosseous membrane's load transferring ability reduces the forces placed on the radiocapitellar articulation, thereby protecting this joint. However, large chronic loading results in attenuation of the membrane fibers, thereby reducing longitudinal stability. Large sustained loads occur after radial head resection with concurrent interosseous membrane tears, resulting in the proximal migration of the radius and disruption of the distal radioulnar joint. Ultimately, the treatment option for severe membrane disruption combined with proximal migration of the radius is the creation of a single bone forearm.