Intra-articular hip disorders in the military population: evaluation and management.

The physical demands of the military expose the hip to extreme forces and stresses and generate a high incidence of hip disorders within this population. Fundamental to the pathophysiology of hip injuries is the underlying anatomy of the joint because problematic femoroacetabular mechanics predispose to injury. FAI is increasingly recognized as the underlying cause of hip disorders and should be considered when assessing a patient with hip complaints. Young, male patients are at increased risk of FAI, especially cam impingement, and high levels of athletic activity during skeletal growth may contribute to the development of cam morphology. A complete evaluation requires a careful history and physical examination combined with multiple imaging modalities. Conservative treatment is indicated for acute hip injury to allow alleviation of inflammation and restoration of normal gait and range of motion. Surgery should be considered for refractory dysfunction, mechanical symptoms, or significant deformities. Arthroscopy has revolutionized the treatment of hip injuries in young, active patients, and is likely to continue to expand in use.

Femoral suspension devices for anterior cruciate ligament reconstruction: do adjustable loops lengthen?

BACKGROUND: Cortical suspension devices are commonly used for femoral graft fixation during anterior cruciate ligament (ACL) reconstructive surgery. Adjustable-length fixation devices provide technical advantages over fixed-length loops but may be more susceptible to lengthening during cyclic loading. HYPOTHESIS: Both fixed-length and adjustable-length femoral cortical suspension devices would withstand ultimate loads greater than those normally experienced by the native ACL and would prevent clinically significant lengthening during prolonged cyclic loading. STUDY DESIGN: Controlled laboratory study. METHODS: Mechanical testing was performed on 3 ACL graft cortical suspensory devices by use of an extended cyclic loading (4500 cycles at 10-250 N) and pull-to-failure protocol. Two adjustable-length devices were additionally tested with the free suture ends tied. RESULTS: Total displacement after 4500 cycles of tensioning at variable loads (expressed as mean ± SD) was 42.45 mm (±7.01 mm) for the Arthrex TightRope RT, 5.76 mm (±0.35 mm) for the Biomet ToggleLoc, and 1.34 mm (±0.03 mm) for the Smith & Nephew EndoButton CL Ultra (P < .001). The Arthrex TightRope reached clinical failure of 3 mm lengthening after fewer cycles (1349 ± 316) than the Biomet ToggleLoc (2576 ± 73) (P < .001). The Smith & Nephew EndoButton did not reach clinical failure during cyclic testing. With the free suture ends tied, after 4500 cycles, the Arthrex TightRope had a significant decrease in lengthening to 13.36 ± 1.86 mm (P < .037) There was also a significant difference in ultimate load between the TightRope (809.11 ± 52.94 N) and the other 2 constructs (P < .001). CONCLUSION: The ultimate load of all graft-fixation devices exceeded the forces likely to be experienced in a patient's knee during the early postoperative rehabilitation period. However, the adjustable-length fixation devices experienced a clinically significant increase in loop lengthening during cyclic testing. This lengthening is partially caused by suture slippage into the adjustable-length loop. CLINICAL RELEVANCE: Adjustable-length ACL graft cortical suspension devices lengthen under cyclic loads because free suture ends are pulled into the adjustable loop. This may allow for graft-fixation device lengthening during the acute postoperative period.

Identification of acetabular labral pathological changes in asymptomatic volunteers using optimized, noncontrast 1.5-T magnetic resonance imaging.

BACKGROUND: Acetabular labral tears as a source of potential hip pain have received a great deal of attention in recent literature. The gold standard for identifying acetabular labral tears is hip arthroscopy, but recent advances in optimized, noncontrast magnetic resonance imaging (MRI) have proven effectiveness in identifying intra-articular hip pathological changes without the invasive nature of hip arthroscopy or gadolinium-enhanced arthrography. There are little data in the literature on imaging results in an asymptomatic population. PURPOSE: The objective of this study was to use an optimized, noncontrast 1.5-T MRI protocol to identify hip abnormalities, including paralabral cysts, in asymptomatic volunteers. STUDY DESIGN: Case series (prevalence); Level of evidence, 4. METHODS: In this study, 42 hips in asymptomatic patients with an average age of 34 years (range, 27-43 years) were prospectively imaged with optimized, noncontrast 1.5-T MRI scans. Two fellowship-trained musculoskeletal radiologists interpreted the scans at 2 different points in time and commented on the presence of labral abnormalities including paralabral cysts. The results were analyzed for both interobserver and intraobserver reliability. RESULTS: Acetabular paralabral cysts were identified in 11 of 42 (26.2%) and 9 of 42 (21.4%) hips by the 2 respective radiologists, with an interobserver reliability of 90.5% (κ = .74) and intraobserver reliability of 95.2% (κ = .87). In addition, acetabular labral tears were identified in 36 of 42 (85.7%) and 34 of 42 (80.9%) hips, with an interobserver reliability of 90.5% (κ = .70) and intraobserver reliability of 95.2% (κ = .83). CONCLUSION: Utilizing an optimized, noncontrast 1.5-T MRI protocol, we report the previously undescribed prevalence of acetabular labral pathological abnormalities and paralabral cysts in a young, asymptomatic population. This emphasizes the importance of correlating patient symptoms with history and physical examination when evaluating patients with hip pain and radiographic abnormalities as defined by MRI criteria. These data demonstrate that labral tears can occur without symptoms.

Correlation of altitude and compartment pressures in porcine hind limbs.

Recent wartime contingencies have demanded frequent aeromedical evacuation of polytrauma patients, all with risk factors for the development of compartment syndrome. This study investigated the effect of altitude on the pressure in uninjured myofascial compartments of 10 pigs as part of a program with the ultimate goal of determining the behavior of an injured extremity in a changing altitude environment. The data showed a trend toward a small increase in pressure with increase in altitude--an average maximal delta of 2.7 mm Hg from the opening pressure. A small increase in compartment pressure, such as seen in this study, in a normal, uninjured compartment would likely go clinically unnoticed. However, aeromedical evacuation missions fly patients with fractures that can affect the physiology of compartments. Potentially, even a small change in pressure can lead to a compartment syndrome. Further study involving a fracture model will be required to further elucidate this clinical question.

In vivo intra-articular negative pressure wound therapy effect on cartilage in a goat model.

This prospective, randomized, blinded pilot study determined if a difference was present in the histology and apoptotic rate of articular cartilage after application of a negative pressure wound therapy (NPWT) device to an uninjured joint surface compared to a control side using Capra hircus goats. The goats were euthanized at 3 or 7 days after surgery. The en bloc joint resection was divided into medial (direct sponge contact) and lateral compartments (no sponge contact; indirect NPWT). In the necropsied cartilage and menisci, there were no gross or histologic/morphometric differences identified by a blinded veterinary pathologist. The percentages of apoptotic and necrotic chondrocytes based on flow cytometry were not statistically different. This study demonstrated that there were no observable deleterious effects to uninjured cartilage from direct or indirect intra-articular NPWT placement. These data suggest that NPWT may be placed safely in an intra-articular position for up to 7 days. Further studies in humans are warranted.

Comparison of vacuum-assisted closure to the antibiotic bead pouch for the treatment of blast injury of the extremity.

The surgical care of modern combatants involves treatment of massive extremity wounds from blast mechanism. Currently up to 70% of combat wounds are extremity related. Clinical outcomes for these patients are dependent on the care of these wounds. The Vacuum-Assisted Closure (VAC) Therapy system (KCI Inc, San Antonio, Texas) is ubiquitous in theater and is often considered the only way to treat these wounds. However, the VAC Therapy system is not without problems. It is expensive and requires extensive amounts of product and machinery, as well as functioning suction, and therefore a power source at all times. In addition, the VAC Therapy system requires a trained and vigilant nursing staff. We hypothesized that the antibiotic bead pouch would be a viable alternative to the VAC Therapy system for such blast injuries. We retrospectively analyzed 2 matched groups of 12 patients in terms of outcome and cost. We found that the VAC Therapy system produced more late methicillin-resistant Staphylococcus aureus infections (30%), more unanticipated returns to the operating room for wound problems (4:12 vs 0:12), and required more surgeries overall until closure of the wounds. In addition, the VAC Therapy system cost $12,000 more for 12 patients than the antibiotic bead pouch. We recommend the bead pouch be considered as an equivalent option to the VAC Therapy system in the treatment of blast injury.

Rotator cuff in asymptomatic volunteers: contrast-enhanced US depiction of intratendinous and peritendinous vascularity.

PURPOSE: To test the hypothesis that regional variations in supraspinatus tendon vascularity exist and can be imaged and quantified in asymptomatic individuals by using contrast material-enhanced ultrasonography (US). MATERIALS AND METHODS: After institutional review board approval and informed consent were obtained, 31 volunteers aged 22-65 years (mean age, 41.5 years) underwent lipid microsphere contrast-enhanced shoulder US performed with an L8-4 transducer operating in contrast harmonic mode and a mechanical index of 0.07 in a HIPAA-compliant protocol. Images were obtained in the volunteers at rest and after exercise. Quantitative analysis was performed by using the time-enhancement postcontrast data derived from four regions of interest (ROIs): bursal medial, articular medial, bursal lateral, and articular lateral. Two 2-minute acquisitions were performed after each contrast material bolus. Baseline enhancement and peak enhancement for each ROI were estimated from these acquisitions. Baseline gray-scale and power Doppler US images of the supraspinatus tendon were obtained by using an L12-5 transducer. The Mann-Whitney nonparametric test was used to test for significant differences between ROIs in all volunteers. RESULTS: In the volunteers at rest before exercise, significant variations in regional enhancement between the articular medial zone and both the bursal medial zone (P = .002) and the bursal lateral zone (P = .003) were observed. Differences in enhancement between the articular medial and articular lateral zones approached significance. Greater differentiation (P < .001) was observed after exercise, with a significant increase in apparent enhancement in each ROI in all volunteers. CONCLUSION: This study revealed the spatial distribution of the blood supply to the supraspinatus tendon in asymptomatic individuals. The addition of exercise to the protocol resulted in a significantly increased level of enhancement compared with that at rest and enabled more sensitive assessment of intratendinous and peritendinous vascularity. SUPPLEMENTAL MATERIAL: http://radiology.rsnajnls.org/cgi/content/full/2483071400/DC1.

Contrast-enhanced ultrasound characterization of the vascularity of the rotator cuff tendon: age- and activity-related changes in the intact asymptomatic rotator cuff.

The natural history of the blood supply to the rotator cuff and its role in the etiology of rotator cuff disease has not been definitively established. To date, there has not been an in-vivo dynamic assessment of the baseline vascularity of the asymptomatic rotator cuff. This study was designed to test the hypothesis that regional variations in supraspinatus tendon vascularity exist with an age-dependent decrease in asymptomatic individuals with intact rotator cuffs. Lipid microsphere, contrast-enhanced ultrasound shoulder examinations were done in 31 patients with a mean age of 41.5 years (range, 22-65 years). Images were obtained at baseline, after contrast administration at rest, and after contrast administration following exercise to visualize the intratendinous blood flow to the supraspinatus tendon. Qualitative and quantitative analysis was performed by determining 4 regions of interest (bursal medial, articular medial, bursal lateral, and articular lateral) with quantification and analysis software (QLAB Philips, Andover, MA) to examine each region of interest and normalize data for interpretation of the mean intensity per pixel. A statistically significant decrease in blood flow to the supraspinatus tendon with age was observed in a comparative analysis of patients aged younger than 40 and older than 40, (P < .05 for all 4 zones after exercise and for the bursal medial, articular medial, and bursal lateral zones after exercise; P = .07 for the articular lateral zone after exercise). A statistically significant increase in blood flow with exercise was observed in an analysis of all patients (P < .001). The age-related decrease in the vascular supply of the tendon observed in this study is consistent with published reports demonstrating an increasing prevalence of rotator cuff pathology with age and may predispose to the development of rotator cuff tendinopathy and, ultimately, attritional tears.

Arthroscopic management of labral tears in the hip: a systematic review of the literature.

Arthroscopic management of labral problems in the hip has become an accepted therapeutic modality in appropriately selected patients. We performed a systematic review of the literature to determine the rate of patient satisfaction that can be expected following acetabular labral débridement. Computerized literature databases were searched from January 1980 to September 2005 to identify relevant articles that met inclusion criteria and had at least 2 years followup. We included patients with symptomatic acetabular labral tears who failed conservative management, were not claiming workers' compensation, and did not have severe arthritis or severe acetabular dysplasia. Following labral débridement this patient population can expect: (1) a patient satisfaction rate of approximately 67% at 3.5 years follow-up; (2) good results by a modified Harris Hip Score in patients who are subjectively satisfied with their outcome; and (3) a complete resolution of mechanical symptoms in nearly 50% of patients with this complaint. Although limited, the current literature supports non workers' compensation patients with isolated labral tears, who lack associated intraarticular abnormality, can receive both symptomatic and functional improvement following arthroscopic labral débridement.