Faculty Bibliography

Ischiofemoral space impingement has become an increasingly recognized extracapsular cause of atypical hip, deep gluteal, and groin pain that can be treated endoscopically. We present a minimally invasive posterolateral technique that preserves the attachment of the iliopsoas tendon and quadratus femoris insertion while decompressing the ischiofemoral space by resecting the lesser trochanter. Furthermore, we present tips to perform this technique in a manner that minimizes the potential for damage to the sciatic nerve. This technique also allows the surgeon to treat concurrent hip pathology arthroscopically.

CONTEXT/BACKGROUND:Data suggest that anorexia nervosa (AN) and obesity are complicated by elevated fracture risk, but skeletal site-specific data are lacking. Traditional bone mineral density (BMD) measurements are unsatisfactory at both weight extremes. Hip structural analysis (HSA) uses dual-energy X-ray absorptiometry data to estimate hip geometry and femoral strength. Factor of risk (φ) is the ratio of force applied to the hip from a fall with respect to femoral strength; higher values indicate higher hip fracture risk. OBJECTIVE:The objective of the study was to investigate hip fracture risk in AN and overweight/obese women. DESIGN/METHODS:This was a cross-sectional study. SETTING/METHODS:The study was conducted at a Clinical Research Center. PATIENTS/METHODS:PATIENTS included 368 women (aged 19-45 y): 246 AN, 53 overweight/obese, and 69 lean controls. MAIN OUTCOME MEASURES/METHODS:HSA-derived femoral geometry, peak factor of risk for hip fracture, and factor of risk for hip fracture attenuated by trochanteric soft tissue (φ(attenuated)) were measured. RESULTS:Most HSA-derived parameters were impaired in AN and superior in obese/overweight women vs controls at the narrow neck, intertrochanteric, and femoral shaft (P ≤ .03). The φ(attenuated) was highest in AN and lowest in overweight/obese women (P < .0001). Lean mass was associated with superior, and duration of amenorrhea with inferior, HSA-derived parameters and φ(attenuated) (P < .05). Mean φ(attenuated) (P = .036), but not femoral neck BMD or HSA-estimated geometry, was impaired in women who had experienced fragility fractures. CONCLUSIONS:Femoral geometry by HSA, hip BMD, and factor of risk for hip fracture attenuated by soft tissue are impaired in AN and superior in obesity, suggesting higher and lower hip fracture risk, respectively. Only attenuated factor of risk was associated with fragility fracture prevalence, suggesting that variability in soft tissue padding may help explain site-specific fracture risk not captured by BMD.

BACKGROUND:Neck circumference is a predictor of cardiovascular disease (CVD) risk. However, detailed assessment of neck fat has not been explored, and the contribution from individual neck fat compartments to CVD risk is unknown. OBJECTIVE:The objective was to measure neck adipose tissue (NAT) compartments and examine relations with CVD risk markers, with the hypothesis that neck adipose tissue (NAT) accumulation preferentially involves specific compartments that contribute differently to metabolic risk. DESIGN/METHODS:We retrospectively studied 303 subjects with successfully treated malignancies or benign etiologies [151 women, 152 men; mean (± SD) age: 55 ± 17 y; mean body mass index (BMI; in kg/m(2)): 28 ± 6] who underwent whole-body positron emission tomography/computed tomography. NAT was measured at the level of the C5 vertebral body, subdivided into posterior (NATpost), subcutaneous (NATsc), and perivertebral (NATperivert) compartments. Data on CVD risk factors (BMI, abdominal circumference, visceral and abdominal subcutaneous adipose tissue, blood pressure, serum lipids, and fasting plasma glucose) were collected. We compared NAT compartments across lean, overweight, and obese groups and performed multivariate regression models correlating NAT with CVD risk factors. Receiver operating characteristic curve and prevalence ratio analyses were performed to examine the association of NAT compartments with metabolic syndrome. RESULTS:NATpost and NATsc were more consistently associated with cardiometabolic risk, especially in women, correlating with visceral adipose tissue (P < 0.0001) and triglycerides (P < 0.001) and a nearly 1.5-fold increase in the prevalence ratio for metabolic syndrome after adjustment for age and BMI (P < 0.05). NATsc was most abundant in women, whereas intermuscular compartments (NATpost and NATperivert) were higher in men. In both sexes, NATpost and NATperivert showed the largest increment between lean and obese subjects. CONCLUSIONS:Neck fat compartments expand differently with increasing adiposity, correlate with CVD risk factors, and are associated with metabolic syndrome, most notably NATpost and NATsc in women. Although neck circumference remains an important method to assess metabolic risk, cross-sectional NAT assessment provides further insight into fat accumulation in the neck. This trial was registered at clinicaltrials.gov as NCT02205021.

Sclerosing epithelioid fibrosarcoma (SEF) is a rare, aggressive malignant neoplasm characterized by small nests and linear arrays of epithelioid cells embedded in a dense collagenous matrix. Very few primary SEFs of bone have been reported. Recognition is critical, as the dense extracellular collagenous matrix can be interpreted as osteoid, leading to misdiagnosis as-osteosarcoma. MUC4 and SATB2 are 2 recently characterized immunohistochemical markers for SEF and osteosarcoma, respectively. In reports to date, osteosarcomas are positive for SATB2 and negative for MUC4, whereas soft tissue SEFs have shown the opposite immunohistochemical profile (SATB2-/MUC4+). The purpose of this study was to characterize the clinicopathologic and immunohistochemical features of 8 primary SEFs of bone. The patients presented at a wide range of ages (25 to 73 y; median 52 y). Tumors mostly involved long bones of the extremities, with 3 cases involving the femur, 2 involving the ulna, and 1 involving the humerus. Other sites of involvement included the second rib (1) and the C6 vertebra (1). Follow-up information was available for 7 patients, 3 of whom developed metastases within 2 years of diagnosis. The other 4 patients were free of local recurrence or metastases at 1, 5, 12, and >84 months of follow-up, respectively. Radiographically, the tumors were predominantly lytic and poorly marginated. Histologically, 6 tumors showed pure SEF morphology, and 2 showed hybrid SEF/low-grade fibromyxoid sarcoma morphology. Focal dystrophic mineralization was seen in 1 case but was limited to areas of necrosis. None of the tumors showed the lace-like pattern of mineralization typical of osteosarcoma. The majority (6/8) of the tumors strongly expressed MUC4. SATB2 was negative in all but 1 case, which showed variable weak to moderate staining in ∼50% of nuclei. In general, the combination of morphology, MUC4 expression, and the absence of SATB2 expression was highly useful in arriving at the correct diagnosis.

PURPOSE/OBJECTIVE:Women with anorexia nervosa (AN) have increased marrow fat despite severe depletion of body fat. Recent studies have suggested that marrow fat composition may serve as a biomarker for bone quality. The purpose of our study was to investigate marrow fat composition of the femur using proton MR spectroscopy ((1)H MRS), and the relationship between measures of marrow fat composition and BMD and body composition in women with AN and normal-weight controls. MATERIALS AND METHODS/METHODS:14 women with AN (29.5±1.9years) and 12 age-matched normal-weight controls underwent (1)H MRS to determine total marrow fat content and marrow fat composition of the femoral diaphysis and soleus intramyocellular lipids und unsaturated muscle lipids. MRI was performed to quantify abdominal fat, thigh fat and muscle areas. Lumbar spine BMD, fat and lean mass were assessed by DXA. RESULTS:Subjects with AN had higher marrow fat content (p<0.05), but similar marrow fat composition (p>0.05) compared to normal-weight controls. There was an inverse association between marrow methylene protons, an estimate of fatty acid (FA) saturated bonds, and lumbar spine BMD (r=-0.52, p=0.008) independent of %ideal body weight (%IBW). Olefinic protons at 5.3ppm, an estimate of FA unsaturated bonds, were inversely associated with body fat depots, independent of %IBW, and positively associated with soleus unsaturation (p≤0.05). CONCLUSION/CONCLUSIONS:Women with AN have higher total femoral marrow fat but similar composition compared to normal-weight controls. The degree of marrow FA saturation correlates inversely with BMD, suggesting that saturated lipids may have negative effects on BMD. The degree of marrow FA unsaturation correlates positively with soleus unsaturation, suggesting that marrow fat composition may be influenced by the same factors as ectopic lipid composition in muscle.

The adipocyte-derived hormone adiponectin promotes metabolic and cardiovascular health. Circulating adiponectin increases in lean states such as caloric restriction (CR), but the reasons for this paradox remain unclear. Unlike white adipose tissue (WAT), bone marrow adipose tissue (MAT) increases during CR, and both MAT and serum adiponectin increase in many other clinical conditions. Thus, we investigated whether MAT contributes to circulating adiponectin. We find that adiponectin secretion is greater from MAT than WAT. Notably, specific inhibition of MAT formation in mice results in decreased circulating adiponectin during CR despite unaltered adiponectin expression in WAT. Inhibiting MAT formation also alters skeletal muscle adaptation to CR, suggesting that MAT exerts systemic effects. Finally, we reveal that both MAT and serum adiponectin increase during cancer therapy in humans. These observations identify MAT as an endocrine organ that contributes significantly to increased serum adiponectin during CR and perhaps in other adverse states.

OBJECTIVE:The purpose of this article is to describe the MRI features of rotator cuff myotendinous junction injuries. MATERIALS AND METHODS/METHODS:We retrospectively identified MRI cases with myotendinous junction injury of the rotator cuff muscles and reviewed clinical, imaging, and surgical records. MR images were reviewed independently by two musculoskeletal radiologists to grade myotendinous junction injuries (strain, partial tear, or complete tear) and to assess for concurrent tendon tears (partial or full thickness) and bone changes (fracture or contusion). RESULTS:The final study group comprised 16 subjects. The mean age was 38 years, with a majority of men (56%). The left shoulder was affected in 56% of subjects, with the dominant upper limb affected in 50%. The mean time between symptoms and MRI was 19 days. Subjects reported heavy lifting (19%), landing on the arm after a fall (19%), or prior shoulder therapeutic injection (25%). Myotendinous junction injuries affected the infraspinatus muscle (50%), followed by the supraspinatus (31%), subscapularis (25%), and teres minor (19%) muscles. About one fifth of subjects presented with more than one muscle affected, and 94% did not present with tears of the corresponding tendons. Most myotendinous junction injuries were strains (80%), followed by partial tears (20%). No complete tears were identified. There was no correlation between myotendinous junction injury and the presence of bone changes or the presence of tendon tears (p > 0.05). CONCLUSION/CONCLUSIONS:Rotator cuff myotendinous junction injuries affect mostly the infra-spinatus and supraspinatus muscles, usually in a strain pattern and without tear of the corresponding tendon attachment.

Patients with neurofibromatosis 1 (NF1), NF2, and schwannomatosis share a predisposition to develop multiple nerve sheath tumors. Previous studies have demonstrated that patients with NF1 and NF2 have reduced quality of life (QOL), but no studies have examined the relationship between whole-body tumor burden and QOL in these patients. We administered a QOL questionnaire (the SF-36) and a visual analog pain scale (VAS) to a previously described cohort of adult neurofibromatosis patients undergoing whole-body MRI. One-sample t-tests were used to compare norm-based SF-36 scores to weighted population means. Spearman correlation coefficients and multiple linear regression analyses controlling for demographic and disease-specific clinical variable were used to relate whole-body tumor volume to QOL scales. Two hundred forty-five patients (142 NF1, 53 NF2, 50 schwannomatosis) completed the study. Subjects showed deficits in selected subscales of the SF-36 compared to adjusted general population means. In bivariate analysis, increased tumor volume was significantly associated with pain in schwannomatosis patients, as measured by the SF-36 bodily pain subscale (rho = -0.287, P = 0.04) and VAS (rho = 0.34, P = 0.02). Regression models for NF2 patients showed a positive relationship between tumor burden and increased pain, as measured by the SF-36 (P = 0.008). Patients with NF1, NF2, and schwannomatosis suffer from reduced QOL, although only pain shows a clear relationship to patient's overall tumor burden. These findings suggest that internal tumor volume is not a primary contributor to QOL and emphasize the need for comprehensive treatment approaches that go beyond tumor-focused therapies such as surgery by including psychosocial interventions.

OBJECTIVE:The purpose of this study was to evaluate the association between distal ulnar morphology and extensor carpi ulnaris (ECU) tendon pathology. MATERIALS AND METHODS/METHODS:We retrospectively reviewed 71 adult wrist MRI studies with ECU tendon pathology (tenosynovitis, tendinopathy, or tear), and/or ECU subluxation. Subjects did not have a history of trauma, surgery, infection, or inflammatory arthritis. MRI studies from 46 subjects without ECU tendon pathology or subluxation were used as controls. The following morphological parameters of the distal ulna were measured independently by two readers: ulnar variance relative to radius, ulnar styloid process length, ECU groove depth and length. Subjects and controls were compared using Student's t test. Inter-observer agreement (ICC) was calculated. RESULTS:There was a significant correlation between negative ulnar variance and ECU tendon pathology (reader 1 [R1], P = 0.01; reader 2 [R2], P < 0.0001; R1 and R2 averaged data, P < 0.0001) and ECU tendon subluxation (P = 0.001; P = 0.0001; P < 0.0001). In subjects with ECU tendon subluxation there was also a trend toward a shorter length (P = 0.3; P <0.0001; P = 0.001) and a shallower ECU groove (P = 0.01; P = 0.03; P = 0.01; R1 and R2 averaged data with Bonferroni correction, P = 0.08). ECU groove depth (P = 0.6; P = 0.8; P = 0.9) and groove length (P = 0.1; P = 0.4; P = 0.7) showed no significant correlation with ECU tendon pathology, and length of the ulnar styloid process showed no significant correlation with ECU tendon pathology (P = 0.2; P = 0.3; P = 0.2) or subluxation (P = 0.4; P = 0.5; P = 0.5). Inter-observer agreement (ICC) was >0.64 for all parameters. CONCLUSION/CONCLUSIONS:Distal ulnar morphology may be associated with ECU tendon abnormalities.

PURPOSE/OBJECTIVE:Abdominal adiposity is associated with low BMD and decreased growth hormone (GH) secretion, an important regulator of bone homeostasis. The purpose of our study was to determine the effects of a short course of GH on markers of bone turnover and bone marrow fat in premenopausal women with abdominal adiposity. MATERIALS AND METHODS/METHODS:In a 6-month, randomized, double-blind, placebo-controlled trial we studied 79 abdominally obese premenopausal women (21-45 y) who underwent daily sc injections of GH vs. placebo. Main outcome measures were body composition by DXA and CT, bone marrow fat by proton MR spectroscopy, P1NP, CTX, 25(OH)D, hsCRP, undercarboxylated osteocalcin (ucOC), preadipocyte factor 1 (Pref 1), apolipoprotein B (ApoB), and IGF-1. RESULTS:GH increased IGF-1, P1NP, 25(OH)D, ucOC, bone marrow fat and lean mass, and decreased abdominal fat, hsCRP, and ApoB compared with placebo (p<0.05). There was a trend toward an increase in CTX and Pref-1. Among all participants, a 6-month increase in IGF-1 correlated with 6-month increase in P1NP (p=0.0005), suggesting that subjects with the greatest increases in IGF-1 experienced the greatest increases in bone formation. A six-month decrease in abdominal fat, hsCRP, and ApoB inversely predicted 6-month change in P1NP, and 6-month increase in lean mass and 25(OH)D positively predicted 6-month change in P1NP (p≤0.05), suggesting that subjects with greatest decreases in abdominal fat, inflammation and ApoB, and the greatest increases in lean mass and 25(OH)D experienced the greatest increases in bone formation. A six-month increase in bone marrow fat correlated with 6-month increase in P1NP (trend), suggesting that subjects with the greatest increases in bone formation experienced the greatest increases in bone marrow fat. Forward stepwise regression analysis indicated that increase in lean mass and decrease in abdominal fat were positive predictors of P1NP. When IGF-1 was added to the model, it became the only predictor of P1NP. CONCLUSION/CONCLUSIONS:GH replacement in abdominally obese premenopausal women for 6 months increased bone turnover and bone marrow fat. Reductions in abdominal fat, and inflammation, and increases in IGF-1, lean mass and vitamin D were associated with increased bone formation. The increase in bone marrow fat may reflect changes in energy demand from increased bone turnover.