Danger zones for flexor tendons in volar plating of distal radius fractures.

PURPOSE: To define a danger zone for volar plates using magnetic resonance imaging by analyzing the position of the flexor tendons at risk around the watershed line. METHODS: We analyzed 40 wrist magnetic resonance images. The location of the flexor pollicus longus (FPL) and index flexor digitorum profundus (FDPi) tendons was recorded at 3 and 6 mm proximal to the watershed line of the distal radius. We measured the distance between the volar margin of the distal radius and the FPL and FDPi tendons, and the coronal position of the tendons. RESULTS: At a point 3 mm proximal to the watershed line, FPL and FDPi were located on average 2.6 and 2.2 mm anterior to the volar margin of the distal radius. This distance increased to 4.7 and 5.3 mm at a point 6 mm proximal to the watershed line. The FPL and FDPi were located at 57% and 42% of the total width of the distal radius from the sigmoid notch at 3 mm from the watershed, and at 66% and 46% at 6 mm from the watershed. CONCLUSIONS: Surgeons should be aware of the close proximity of the flexor tendons to the volar cortex of the distal radius proximal to the watershed line and their radial to ulnar position. Three millimeters proximal to the watershed line, plate placement more than 2 mm anterior to the volar cortex or the use of plates thicker than 2 mm poses a high risk for directly contacting flexor tendons. CLINICAL RELEVANCE: This article may prove to be helpful in avoiding flexor tendon injury during volar plate fixation.

Predicting a safe screw length for volar plate fixation of distal radius fractures: lunate depth as a marker for distal radius depth.

PURPOSE: We hypothesized that the lunate depth as measured on plain lateral radiographs can be used to predict distal radius depth radially and ulnarly and serve as a useful reference for intraoperative screw placement in volar plate fixation of distal radius fractures. METHODS: Plain radiographs and magnetic resonance imaging (MRI) of the wrists of 30 patients were reviewed. The lunate depth and the maximal depth of the distal radius were determined from plain lateral radiographs. Depth of the distal radius, measured in quartiles, was determined from axial MRI images, and the lunate depth was obtained from sagittal MRI images. The depth of the distal radius in each quartile was then calculated related to the lunate depth. RESULTS: The mean depth of the lunate on plain radiographs and MRI was 17.5 mm and 17.4 mm, respectively. The depth of the distal radius from ulnar to radial was 18.4 mm, 20.2 mm, 19.4 mm, and 15.1 mm for the 1st through 4th quartiles, respectively. The depth of the distal radius is the least radially (4th quartile), with a mean 87% of the lunate depth, and greatest in the 2nd quartile, with a mean 116% of the lunate depth. CONCLUSIONS: The depth of the lunate as measured on plain radiographs can be used as a marker for drilling and placement of safe screw lengths during volar plate fixation of distal radius fractures. We recommend that surgeons use the lunate depth as an estimate for the length of their longest screw when fixing distal radius fractures with volar plate techniques to avoid extensor tendon irritation and rupture. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic III.

Radial nerve injuries.

Radial nerve injuries continue to challenge hand surgeons. The course of the nerve and its intimate relationship to the humerus place it at high risk for injury with humerus fractures. We present a review of radial nerve injuries with emphasis on their etiology, workup, diagnosis, management, and outcomes.

External hemipelvectomy pelvic ring stabilization: the unique application of chimeric lower extremity pedicled fillet flaps.

Reconstruction of large external hemipelvectomy oncologic defects of the proximal limb and trunk remains a formidable surgical challenge. Large pelvic defects can result in exposed bones, neurovascular structures, and surgical hardware due to a paucity of soft tissue coverage. When the size of a hemipelvectomy defect precludes coverage by local posterior- or anterior-based hemipelvectomy flaps, the use of other local flaps must be considered before resorting to free tissue transfer. The rectus abdominis myocutaneous pedicled flap is the most commonly used locoregional flap for soft tissue coverage of large hemipelvectomy soft tissue defects. The concept of utilizing parts from otherwise nonsalvageable limb components in reconstruction is well described in the literature and referred to as the "spare parts" concept. Utilization of these distal "spare parts" has the advantage of obtaining sufficient soft tissue coverage while concurrently obviating additional donor-site morbidity. These spare parts can be utilized as either pedicled or free fillet flaps. This paper describes the unique use of in-continuity chimeric pedicled fillet flaps of the lower extremity to reconstruct and stabilize the pelvic ring, to obliterate dead space, and to provide overlying soft tissue coverage.

Prediction of coracoid thickness using a glenoid width-based model: implications for bone reconstruction procedures in chronic anterior shoulder instability.

BACKGROUND: Chronic anterior shoulder instability with glenoid bone loss can be a very challenging clinical problem. Significant bone loss is commonly managed with the Latarjet procedure. However, in some cases with severe glenoid bone loss, iliac crest bone grafting is required to obtain a graft of adequate size. Iliac crest bone graft is associated with high rates of donor-site complications. Whereas glenoid dimensions can be determined by use of 3-dimensional computed tomography reconstructions, the thickness of the coracoid cannot be easily measured. This study aims to define a ratio between glenoid width and coracoid thickness that can be used in preoperative planning to determine whether coracoid transfer will yield adequate bone graft to restore glenoid contour or whether iliac crest bone graft must be taken. METHODS: We studied 100 paired cadaveric scapulae (50 male and 50 female scapulae). The bony dimensions of the coracoid and glenoid were measured for each specimen. RESULTS: Coracoid and glenoid dimensions are provided. The mean thickness of the male coracoid was 35.4% of the width of the glenoid. The mean female coracoid thickness was 34.4% of the glenoid width. DISCUSSION: A new biomorphologic model is presented to predict coracoid thickness and the ability of the Latarjet procedure to restore stability to a given bone-deficient glenoid. This model may aid the shoulder surgeon in preoperative planning and help promote successful outcomes in glenoid reconstruction surgery by determining whether a Latarjet procedure or iliac crest bone graft is the most appropriate procedure given the predicted amount of coracoid bone graft available.

Necrotizing fasciitis.

Necrotizing fasciitis is a rare but life-threatening soft-tissue infection characterized by rapidly spreading inflammation and subsequent necrosis of the fascial planes and surrounding tissue. Infection typically follows trauma, although the inciting insult may be as minor as a scrape or an insect bite. Often caused by toxin-producing, virulent bacteria such as group A streptococcus and associated with severe systemic toxicity, necrotizing fasciitis is rapidly fatal unless diagnosed promptly and treated aggressively. Necrotizing fasciitis is often initially misdiagnosed as a more benign soft-tissue infection. The single most important variable influencing mortality is time to surgical débridement. Thus, a high degree of clinical suspicion is necessary to avert potentially disastrous consequences. Orthopaedic surgeons are often the first to evaluate patients with necrotizing fasciitis and as such must be aware of the presentation and management of this disease. Timely diagnosis, broad-spectrum antibiotic therapy, and aggressive surgical débridement of affected tissue are keys to the treatment of this serious, often life-threatening infection.

Effects of a supervised home-based aerobic and progressive resistance training regimen in women infected with human immunodeficiency virus: a randomized trial.

BACKGROUND: Women infected with human immunodeficiency virus (HIV) increasingly demonstrate abnormalities in fat distribution and metabolism; however, the effects of a home-based exercise regimen in this group have not been investigated. METHODS: We conducted a 16-week randomized intervention study of a supervised home-based progressive resistance training and aerobic exercise program in 40 HIV-infected women with increased waist-hip ratio and self-reported fat redistribution. Cross-sectional muscle area and muscle attenuation were measured by computed tomography. Cardiorespiratory fitness was determined by calculated maximum oxygen consumption (VO2max) and strength by 1-repetition maximum. RESULTS: Cardiorespiratory fitness (VO2max) was markedly lower at baseline (median [95% confidence interval], 15.4 [8.3-25.2] mL x kg(-1) x min(-1)) than reported values for healthy female subjects (26-35 mL x kg(-1) x min(-1)). Subjects randomized to exercise had significant improvement in mean +/- SEM VO2max (1.5 +/- 0.8 vs -2.5 +/- 1.6 mL x kg(-1) x min(-1); P<.001) and endurance (1.0 +/- 0.3 vs -0.6 +/- 0.3 minute; P<.001). Strength increased at the knee extensors, pectoralis, knee flexors, shoulder abductors, ankle plantar flexors, and elbow flexors (all P<.001). Total muscle area (6 +/- 1 vs 2 +/- 1 cm2; P = .02) and attenuation (2 +/- 1 vs -1 +/- 1 Hounsfield unit; P = .03) increased in the exercise group. No significant difference was seen in lipid levels, blood pressure, or abdominal visceral fat between the groups, but subjects randomized to exercise reported improved energy and appearance. CONCLUSIONS: A 16-week, supervised, home-based exercise regimen improved measures of physical fitness in HIV-infected women. The effects on strength were most significant, but improvements in cardiorespiratory fitness, endurance, and body composition were also seen.

Differential effects of metformin and exercise on muscle adiposity and metabolic indices in human immunodeficiency virus-infected patients.

The HIV-lipodystrophy syndrome is associated with fat redistribution and metabolic abnormalities, including insulin resistance (IR). The mechanisms and treatment strategies for IR in HIV-lipodystrophy are unclear, but data suggest that intramuscular lipids contribute to IR in this population. We previously showed that metformin and exercise improve hyperinsulinemia more than metformin alone in HIV-lipodystrophy. Now we investigate the effects of these treatment strategies on thigh muscle adiposity measured by computed tomography and additional body composition measures. Twenty-five HIV-infected patients on stable antiretroviral therapy with hyperinsulinemia and fat redistribution participated in a prospective, randomized, 3-month study of metformin alone or metformin and resistance training three times a week. Thigh muscle adiposity decreased significantly more as shown by increased muscle attenuation [2.0 (range, 0.5-5.0) vs. -1.0 (-3.5-0), P = 0.04] and sc leg fat tended to decrease more [-3.3 (-7.5-4.3) vs. 0.8 (-2.1-9.5), P = 0.06] in the combined treatment group in comparison with metformin alone. In multivariate analysis, change in thigh muscle adiposity remained a significant predictor of change in insulin (P = 0.04), controlling for changes in other body composition measurements. These data suggest that muscle adiposity, in addition to other fat depots, is an important determinant of hyperinsulinemia and that exercise has complex effects on regional fat depots in HIV-infected patients. Reduction in muscle adiposity may be an important mechanism by which exercise improves hyperinsulinemia in this population.

Acute regulation of adiponectin by free fatty acids.

Little is known about the acute regulation of adiponectin in humans. In animal studies, adiponectin increases the clearance of free fatty acids (FFA) from the circulation by increasing skeletal uptake and oxidation of lipid, thereby regulating the FFA concentration. However, it is unknown if FFA regulate adiponectin. The aim of the present study was to investigate the effect of an acute reduction in free fatty acids on adiponectin concentration in healthy subjects. Ten normal male subjects were admitted for 2 inpatient visits and randomized to receive either acipimox (500 mg orally at 2 am and again at 6 am) or placebo on the first visit and vice versa on the second visit. Adiponectin, FFA, insulin and glucose were measured at 7:45 am. FFA concentrations were significantly lower after acipimox than placebo administration (0.08 +/- 0.02 mEq/L v 0.35 +/- 0.53 mEq/L, P <.05). Adiponectin concentrations were also significantly lower after acipimox than placebo administration (7.4 +/- 1.2 microg/mL v 10.3 +/- 1.7 microg/mL, P <.05). The change in FFA between acipimox and placebo correlated significantly with the change in adiponectin (r = 0.66, P <.05), eg, the larger the reduction in FFA in response to acipimox, the larger the reduction in adiponectin. These results suggest that acute lowering of FFA is associated with decreased adiponectin concentrations.