George T. Liu

Biomechanical topography of human articular cartilage in the first metatarsophalangeal joint

The objective of this study was to provide a map of cartilage biomechanical properties, thickness, and histomorphometric characteristics in the human, cadaveric first metatarso-phangeal joint, to determine if normal articular cartilage was predisposed topographically to biomechanical mismatches in articulating surfaces. Cartilage intrinsic material properties and thickness were obtained from seven pairs of human, freshly frozen, cadaveric, metatarsophalangeal joints using an automated creep indentation apparatus under conditions of biphasic creep. Eight sites were tested: four on the metatarsal head, two on the proximal phalanx base, and one on each sesamoid bone to obtain the aggregate modulus, Poissons ratio, permeability, shear modulus, and thickness. Cartilage in the lateral phalanx site of the left metatarsal head had the largest aggregate modulus (1.34 MPa), whereas the softest tissue was found in the right medial sesamoid (0.63 MPa). The medial phalanx region of the right joint was the most permeable (4.56 x 10-15 meter4/Newton-second), whereas the medial sesamoid articulation of the metatarsal head of the left joint was the least permeable (1.26 x 10-15 meter4/Newton-second). Material properties and thickness are indicative of the tissues functional environment. The lack of mismatches in cartilage biomechanical properties of the articulating surfaces found in this study may be supportive of clinical observations that early degenerative changes, in the absence of traumatic events, do not occur at the selected test sites in the human first metatarsophalangeal joint.

Primary Sjogren's syndrome in men.

OBJECTIVE--To describe the clinical expression of primary Sjögrens syndrome (SS) in men, focusing on extraglandular manifestations (EGM) and serological markers of disease. METHODS--In a cross sectional and comparative study, adult men with primary SS were identified from a cohort study on SS, and 26 age matched adult women with primary SS were selected as a control group. All patients met the European classification criteria for SS. They were compared for demographic, clinical and laboratory findings. RESULTS--Thirteen men with primary SS were identified. Mean age at onset was 39 (SEM 4) years and mean duration of disease was 7.8 (1) years. Sicca complex or parotitis was the presenting feature in eight patients (61.5%), and an EGM in five (38.5%). During the course of the disease, EGM were present in 12 patients (92%), polyarthralgias and lymphopenia being the most frequent (38.5% each). Rheumatoid factor was positive in 73% of patients, antinuclear antibodies in 85%, anti-(SS-A) in 62%, and anti-(SS-B) in 46%. No statistical differences in the frequency of EGM or in the presence of autoantibodies were observed between men and women. However, men patients were more likely to have EGM. CONCLUSION--Primary SS in men is an uncommon condition with clinical and serological characteristics similar to those observed in women. Sex hormones may be incriminated in the pathogenesis of SS. However, it remains poorly understood whether sex hormones play a major role in the severity of disease and have any importance with regard to treatment.

The economics of limb salvage in diabetes.

Background: Limb salvage requires early prevention therapy, knowledgeable use of wound care technology, and active management of peripheral vascular disease. This field has changed considerably over the past decade, with new advanced wound healing products and minimally invasive surgery for peripheral vascular disease. Treatment can be very costly in terms of medical and human resources. Evaluation of the clinical and economic impact of medical care is becoming more important as the population with diabetes and the need to contain the cost of health care simultaneously increase. The aim of this study was to review the economic impact of prevention therapies, wound care, and peripheral vascular disease interventions to prevent major lower extremity amputations. Methods: The authors reviewed the economic impact of prevention therapy, wound care, and peripheral vascular disease interventions to prevent lower extremity amputations. Results: Length of stay in the hospital and intensive care drive the cost of treatment. Surgical intervention and complications for foot ulcers, amputations, and peripheral vascular disease are significant factors in the cost of limb salvage. Conclusions: Not surprisingly, prevention and evidenced-based treatments are the most cost-effective way of reducing the use of medical resources and improving and prolonging productive lifestyles. Future prospective studies need to be conducted to more accurately understand the financial impact of limb salvage.

Human Articular Cartilage Biomechanics of the Second Metatarsal Intermediate Cuneiform Joint

Intrinsic material properties and histomorphometry of freshly frozen, human cadaveric cartilage from the second metatarsal intermediate cuneiform (SMIC) articulation were obtained to provide biomechanical mapping of the surfaces. The biphasic creep indentation methodology and an automated creep indentation apparatus were used to measure aggregate modulus, Poissons ratio, permeability, shear modulus, and thickness. Biomechanical experiments were performed on four sites of the SMIC joint in 14 specimens (seven pairs): two sites in the second metatarsal base and two sites in the intermediate cuneiform head. Results of the study indicate that no significant variations exist in the biomechanical comparisons between specific articulations, gross articulations, and left and right joints. For example, cartilage from the second metatarsal base and intermediate cuneiform head had an aggregate modulus of 0.99 MPa and 1.05 MPa, respectively. The Poissons ratio and permeability of all test sites grouped together were found to be 0.08 and 3.05 x 10(-15) m4/N.s, respectively. Cartilage thickness was measured at 0.61 mm. This biomechanical study suggests that similarities in cartilage properties may be beneficial in preventing the human SMIC articulation from developing early degenerative changes. Histological evaluation demonstrated that SMIC cartilage exhibits structural characteristics (such as the absence of chondrocyte columnar arrangement in the deep zone) which may be typical of cartilage that does not experience habitually high compressive stresses. This knowledge could aid surgeons in generating a deeper perspective of the relationship between clinical pathologies of articular cartilage and intrinsic biomechanical etiologies of degenerative joint diseases.

Spring ligament complex: Illustrated normal anatomy and spectrum of pathologies on 3T MR imaging

The spring (plantar calcaneonavicular) ligament complex connects the calcaneus and navicular bone of the foot and serves as the primary static stabilizer of the medial longitudinal arch of the foot. In this article, we describe the normal anatomy of the spring ligament complex, illustrate 3T magnetic resonance imaging appearances in its normal and abnormal states, and discuss the pathological associations with relevant case examples.

A Biomechanical Analysis of Interference Screw Versus Bone Tunnel Fixation of Flexor Hallucis Longus Tendon Transfers to the Calcaneus

ABSTRACT The flexor hallucis longus tendon transfer is commonly used to restore function in chronic Achilles tendon ruptures and chronic Achilles tendinopathy. The tendon is often secured to the calcaneus either through a bone tunnel or by an interference screw. We hypothesized that tenodesis using the bone tunnel method would be mechanically superior to interference screw fixation for flexor hallucis longus transfers. Eight matched pairs of cadaveric specimens were assigned randomly to the bone tunnel or interference screw technique and were loaded to failure. Biomechanical analysis was performed to evaluate the ultimate strength, peak stress, Youngs modulus, failure strain, and strain energy. Unpaired comparison, paired comparison, and linear regression analyses were used to determine statistical significance. A slight 22% ± 9% decrease in Youngs modulus and a 52% ± 18% increase of strain energy were found in the interference screw group. However, no differences in ultimate strength, peak stress, or failure strain were seen between the 2 groups on paired comparison. Our findings suggest that interference screw fixation provides similar spontaneous biomechanical properties to the use of a bone tunnel for flexor hallucis longus transfer to the calcaneus. The interference screw is a practical option for fixation of the flexor hallucis longus tendon to the calcaneus and can be performed through a single incision approach. &NA; Level of Clinical Evidence: 5

Scoring Mental Health Quality of Life With the SF-36 in Patients With and Without Diabetes Foot Complications

The aim of this study was to examine if using orthogonal and oblique factor analysis detect changes in health-related quality of life differently in diabetic patients on the Short Form-36 (SF-36) survey. A total of 155 patients had diabetic foot complications (DFC), and 145 patients had no DFCs. The SF-36 Physical Component Summary (PCS) and Mental Component Summary (MCS) scores were calculated using scoring coefficients determined by orthogonal and oblique rotation principle component analyses of the subscales. The DFC group had lower orthogonal (P < .00001) and oblique PCS scores (P < .00001). However, despite lower Mental Health subscale scores in the patients with DFCs, orthogonal MCS scores (P = .156) did not differ. In contrast, the oblique MCS scores reflected the difference in the Mental Health subscale (P = .0005). Orthogonal and oblique PCS scores did not differ significantly. However, orthogonal MCS scores were significantly higher than oblique MCS scores in those with DFCs (P = .0004) and without DFCs (P = .005). The shorter, 12-item SF-12 survey demonstrated similar results. Poorer physical function leads to higher orthogonal MCS scores than if determined by oblique scoring coefficients since Physical Function, Bodily Pain, and General Health are weighted more negatively in orthogonal coefficients when calculating the MCS score. Oblique scoring coefficients may address this issue, but further study is necessary to confirm whether oblique MCS scores accurately represent the mental health of patients with diabetic foot disease.

Biomechanical Cadaveric Analysis of Biotenodesis Screw Versus Bone Tunnel Fixation Methods in Flexor Hallucis Longus Transfers

The Achilles tendon is the largest tendon in the human body. It connects the gastrosoleus complex to the calcaneus bone in the foot. It thus allows for transfer of force and heel elevation during forward propulsion of the foot in gait. It is also one the most commonly injured tendons. (1). Acute repair or acute intervention for non-operatively treated tendons do well to restore function. However, chronic Achilles tendon ruptures often require tendon transfer rather than attempt at primary repair. The treatment considered the gold standard is the transfer of the flexor hallucis longus (FHL) tendon to the Achilles insertion of the calcaneus (2).Copyright

Gender Differences on SF-36 Patient-Reported Outcomes of Diabetic Foot Disease

The primary aim of this study was to evaluate the impact of gender on health-related quality of life (HRQOL) using a generic (Short Form–36 [SF-36]) and region-specific (Foot and Ankle Ability Measure [FAAM]) health measurement tool among a matched cohort of male and female patients with diabetes-related foot complications. The HRQOL of 240 patients with diabetic foot disease was measured using the SF-36 and the FAAM surveys. A total of 120 male patients were matched with 120 female patients with the same primary diagnosis, age, type, and duration of diabetes and insulin use. The SF-36 physical component summary (PCS) and mental component summary (MCS) scores were calculated using orthogonal and oblique rotation methods. The median age of the respondents was 54 years (interquartile range = 46-61). No differences in patient characteristics were found between genders. Among the SF-36 subscales, women reported significantly worse physical function (P = .014) and bodily pain (P = .021) scores with a trending decrease in general health score (P = .067). Subsequently, women had worse orthogonal (P = .009) and oblique PCS scores (P = .036) than men. However, orthogonal (P = .427) or oblique (P = .140) MCS scores did not differ between groups. No significant differences in FAAM scores with respect to gender were appreciated. Our findings suggest that in patients with diabetic foot disease, women tend to report lower physical HRQOL compared with men. In efforts to increase compliance, providers should recognize the impact of gender on patients’ perceptions of foot-related complications of diabetes. This knowledge may improve outcomes by adapting more individualized and gender-specific approaches to patients.

Three-Dimensional Computed Tomographic Characterization of Normal Anatomic Morphology and Variations of the Distal Tibiofibular Syndesmosis

ABSTRACT Malreduction of distal tibiofibular syndesmosis (DTFS) leads to poor functional outcomes after ankle fracture surgery. Difficulty achieving anatomic alignment of the syndesmosis is due to variable morphology of the fibular incisura of the tibia and a paucity of literature regarding its morphologic characteristics. We surveyed 775 consecutive ankle computed tomography (CT) scans performed from June 2008 to December 2011, and 203 (26.2%) were included for evaluation. Two observers performed quantitative measurements and qualitative evaluated fibular incisura morphology. Tang ratios for fibular rotation, anterior and posterior tibiofibular distances, fibular incisura depth, and subjective morphologies on CT were assessed using conventional multiplanar reconstruction (MPR) and maximum intensity projections (MIPs). On conventional CT, the mean Tang ratio was 0.97 ± 0.06; the mean anterior tibiofibular distance was 2.17 ± 0.87 mm; the mean posterior tibiofibular distance was 3.52 ± 0.94 mm; and the mean depth of fibular incisura was 3.29 ± 1.19 mm. Five morphologic variations of the fibular incisura were identified: crescentic, trapezoid, flat, chevron, and widows peak. The most common fibular incisura morphology was crescentic (61.3%), followed by trapezoid shape (25.1%); the least common morphology was flat (3.1%). Interobserver variability with intraclass correlation coefficient (ICC) was slightly higher for all quantitative measures on MPR (ICC = 0.72 to .81) versus MIP (ICC = 0.64 to 0.75). ICC for incisura shape and depth assessments was poor on both modalities (0.13 to 0.38). This comprehensive CT study reports on quantitative and qualitative descriptive measures to evaluate fibular incisura morphologies and fibular orientation. It also defines the frequency of DTFS measures and the interobserver performance on 2 CT evaluation methods. &NA; Level of Clinical Evidence: 5