Hierarchies of Extracellular Matrix and Mineral Organization in Bone of the Craniofacial Complex and Skeleton

Structural hierarchies are common in biologic systems and are particularly evident in biomineralized structures. In the craniofacial complex and skeleton of vertebrates, extracellular matrix and mineral of bone are structurally ordered at many dimensional scales from the macro level to the nano level. Indeed, the nanocomposite texture of bone, with nanocrystals of apatitic mineral embedded within a crosslinked matrix of fibrillar and nonfibrillar proteins, imparts to bone the very mechanical properties and toughness it needs to function in vital organ protection, musculoskeletal movement and mastication. This article focuses on how hierarchies of extracellular matrix protein organization influence bone cell behavior, tissue architecture and mineralization. Additional attention is given to recent work on the molecular determinants of mineral induction in bone, and how the mineralization process is subsequently regulated by inhibitory proteins.

Mother-Infant Interaction, Life Events and Prenatal and Postpartum Depressive Symptoms Among Urban Minority Women in Primary Care

OBJECTIVES

Prenatal and postpartum depression are significant mental health problems that can have negative effects on mother-infant interactions. We examined the relationships among mother-infant interactions, depressive symptoms, life events, and breastfeeding of low-income urban African American and Hispanic women in primary care settings.

METHODS

Participants were 89 African American and Hispanic women who were part of a larger mental health intervention study conducted in community health centers. Questionnaire data on depression, as well as negative and positive life events, were collected during pregnancy and at three-months postpartum, while mother-infant interaction observations and breastfeeding practice were only collected at three-months postpartum.

RESULTS

The ratings of maternal behavior for 'depressed' mothers did not differ from 'nondepressed' mothers. Except for gaze aversion behavior, infants' behavior while interacting with their mothers did not differ by maternal depression level. Hierarchical regression analyses revealed that maternal positive life events positively predicted infant interactional summary ratings, while maternal negative life events were inversely associated with maternal interactional summary ratings.

CONCLUSIONS

To improve services in primary care, perinatal screenings for depression can help identify those women most at risk. When follow-up use of structured diagnostic instruments is not possible or cost-effective, clinician assessment of severity of depression will determine women with clinical levels of depression. Reducing negative life events is beyond the control of women or clinicians but cognitive interventions to help women focus on positive life events can reduce the deleterious effects of depression on mothers and their infants.

Nonprescribed antimicrobial drugs in Latino community, South Carolina

We investigated in a sample of Latinos the practices of antimicrobial drug importation and use of nonprescribed antimicrobial drugs. In interviews conducted with 219 adults, we assessed health beliefs and past and present behaviors consistent with acquiring antimicrobial drugs without a prescription in the United States. Many (30.6%) believed that antimicrobial drugs should be available in the United States without a prescription. Furthermore, 16.4% had transported nonprescribed antimicrobial drugs into the United States, and 19.2% had acquired antimicrobial agents in the United States without a prescription. A stepwise logistic regression analysis showed that the best predictors of having acquired nonprescribed antimicrobial drugs in the United States were beliefs and behavior consistent with limited regulations on such drugs. Many persons within the Latino community self-medicate with antimicrobial drugs obtained without a prescription both inside and outside the United States, which adds to the reservoir of antimicrobial drugs in the United States.

Tissue engineering of cartilage using an injectable and adhesive chitosan-based cell-delivery vehicle

OBJECTIVE

Adult articular cartilage shows a limited intrinsic repair response to traumatic injury. To regenerate damaged cartilage, cell-assisted repair is thus viewed as a promising therapy, despite being limited by the lack of a suitable technique to deliver and retain chondrogenic cells at the defect site.

DESIGN

We have developed a cytocompatible chitosan solution that is space-filling, gels within minutes, and adheres to cartilage and bone in situ. This unique combination of properties suggested significant potential for its use as an arthroscopically injectable vehicle for cell-assisted cartilage repair. The primary goal of this study was to assess the ability of this polymer system, when loaded with primary articular chondrocytes, to support cartilage formation in vitro and in vivo. The chitosan gel was cultured in vitro, with and without chondrocytes, as well as injected subcutaneously in nude mice to form subcutaneous dorsal implants. In vitro and in vivo constructs were collectively analyzed histologically, for chondrocyte mRNA and protein expression, for biochemical levels of glycosaminoglycan, collagen, and DNA, and for mechanical properties.

RESULTS

Resulting tissue constructs revealed histochemical, biochemical and mechanical properties comparable to those observed in vitro for primary chondrocytes cultured in 2% agarose. Moreover, the gel was retained after injection into a surgically prepared, rabbit full-thickness chondral defect after 1 day in vivo, and in rabbit osteochondral defects, up to 1 week.

CONCLUSIONS

The in situ-gelling chitosan solution described here can support in vitro and in vivo accumulation of cartilage matrix by primary chondrocytes, while persisting in osteochondral defects at least 1 week in vivo.

Health care seeking among urban minority adolescent girls: the crisis at sexual debut

PURPOSE

We wanted to explore the context of help seeking for reproductive and nonreproductive health concerns by urban adolescent girls.

METHODS

We undertook a qualitative study using in-depth interviews of African American and Latina girls (n = 22) aged 13 to 19 years attending public high schools in the Bronx, NY.

RESULTS

Before the onset of sexual activity, most girls meet health needs within the context of the family, relying heavily on mothers for health care and advice. Many new needs and concerns emerge at sexual debut. Key factors modulating girls' ability to address their health needs and concerns include (1) the strategy of selective disclosure of information perceived to be harmful to close family relationships or threaten privacy; (2) the desire for personalized care, modeled on the emotional and physical care received from mother; and (3) relationships with physicians that vary in quality, ranging from distant relationships focused on providing information to close continuity relationships. Core values shaping these processes include privacy, a close relationship with the mother, and a perception of sexual activity as dangerous. No girl was able to meet her specific reproductive health needs within the mother-daughter relationship. Some find nonmaternal sources of personalized health care and advice for reproductive health needs, but many do not.

CONCLUSIONS

Adolescent girls attempt to meet reproductive health needs within a context shaped by values of privacy and close mother-daughter relationships. Difficulty balancing these values often results in inadequate support and care.

Tetrapolar Measurement of Electrical Conductivity and Thickness of Articular Cartilage

A tetrapolar method to measure electrical conductivity of cartilage and bone, and to estimate the thickness of articular cartilage attached to bone, was developed. We determined the electrical conductivity of humeral head bovine articular cartilage and subchondral bone from a 1- to 2-year-old steer to be 1.14±0.11S/m(mean±sd,n=11) and 0.306±0.034S/m,(mean±sd,n=3), respectively. For a 4-year-old cow, articular cartilage and subchondral bone electrical conductivity were 0.88±0.08S/m(mean±sd,n=9) and 0.179±0.046S/m(mean±sd,n=3), respectively. Measurements on slices of cartilage taken from different distances from the articular surface of the steer did not reveal significant depth-dependence of electrical conductivity. We were able to estimate the thickness of articular cartilage with reasonable precision (<20% error) by injecting current from multiple electrode pairs with different inter-electrode distances. Requirements for the precision of this method to measure cartilage thickness include the presence of a distinct layer of calcified cartilage or bone with a much lower electrical conductivity than that of uncalcified articular cartilage, and the use of inter-electrode distances of the current injecting electrodes that are on the order of the cartilage thickness. These or similar methods present an attractive approach to the non-destructive determination of cartilage thickness, a parameter that is required in order to estimate functional properties of cartilage attached to bone, and evaluate the need for therapeutic interventions in arthritis.

Adapting psychosocial intervention research to urban primary care environments: a case example

PURPOSE

We wanted to describe the unique issues encountered by our research team in testing an intervention to reduce perinatal depression in real-world community health centers.

METHOD

We used a case study of an experience in conducting a randomized controlled trial designed to test the effectiveness of a low-cost multimodal psychosocial intervention to reduce prenatal and postpartum depression. Low-income minority women (N = 187) with low-risk pregnancies were randomly assigned to the intervention or treatment as usual. Outcomes of interest were depressive symptoms and social support assessed at 3 months' postpartum.

RESULTS

Our intervention was not associated with changes in depressive symptoms or social support. Challenges in implementation were related to participant retention and intervention delivery. Turnover of student therapists affected continuity in participant-therapist relationships and created missed opportunities to deliver the intervention. The academic-community partnership that was formed also required more involvement of health center personnel to facilitate ownership at the site level, especially for fidelity monitoring. While attentive to cultural sensitivity, the project called for more collaboration with participants to define common goals and outcomes. Participatory research strategies could have anticipated barriers to uptake of the intervention and achieved a better match between outcomes desired by researchers and those of participants.

CONCLUSION

Several criteria for future research planning emerged: assessing what the population is willing and able to accept, considering what treatment providers can be expected to implement, assessing the setting's capacity to accommodate intervention research, and collecting and using emerging unanticipated data.

Purification of ovocalyxin-32, a novel chicken eggshell matrix protein

The eggshell is a highly ordered structure resulting from the deposition of calcium carbonate and an organic matrix from the acellular uterine fluid. Characterization of the individual matrix components is necessary to determine their influence upon calcite crystal shape, size, and orientation during eggshell calcification. We have purified and sequenced a novel 32-kDa protein, ovocalyxin-32 (OCX-32), which is present at high levels in the uterine fluid during the terminal phase of eggshell formation, and is localized predominantly in the outer eggshell. Database searches identified expressed sequence tags (ESTs) whose alignment yielded the complete cDNA. OCX-32 protein possesses limited identity (32%) to two unrelated proteins: latexin, a carboxypeptidase inhibitor expressed in rat cerebral cortex and mast cells, and to a skin protein that is encoded by a retinoic acid receptor-responsive gene, TIG1. The timing of OCX-32 secretion into the uterine fluid suggests that it may play a role in the termination of mineral deposition.

Women's experiences of abnormal cervical cytology: illness representations, care processes, and outcomes

BACKGROUND

We wanted to explore the conceptual representations of illness and experiences with care among women who have learned of an abnormal Papanicolaou (Pap) smear result.

METHODS

The study took place in 2 primary care, family practice clinics serving low-income, multiethnic patients in the Bronx, New York City. We conducted qualitative, semistructured telephone interviews with 17 patients who had recently learned of abnormal findings on a Pap smear. After a preliminary coding phase, the investigators identified 2 important outcomes: distress and dissatisfaction with care, and factors affecting these outcomes. A model was developed on a subset of the data, which was then tested on each transcript with an explicit search for disconfirming cases. A revised coding scheme conforming to the dimensions of the model was used to recode transcripts.

RESULTS

Women reported complex, syncretic models of illness that included both biomedical and folk elements. Many concerns, especially nonbiomedical concerns, were not addressed in interactions with physicians. An important source of both distress and dissatisfaction with care was the women's lack of understanding of the inherent ambiguity of Pap smear results. When perceived care needs, which included emotional support as well as information, were not met, distress and dissatisfaction were greatly increased.

CONCLUSION

In this study, patients' illness models and expectations of care were not routinely addressed in their conversations with physicians about abnormal Pap smear results. When physicians can take the time to review patients' illness models carefully, distress and dissatisfaction with care can be reduced considerably.

Prenatal and Postpartum Depression among Low-Income Dominican and Puerto Rican Women

This longitudinal study examined depression symptoms among pregnant, low-income, urban Latinas, primarily Puerto Ricans and Dominicans, receiving obstetrical services in community health centers. In all, 106 women were interviewed in late pregnancy, 47 were interviewed again 2 to 3 weeks postpartum, and 42 three months postpartum. Elevated levels of depressive symptoms were evident in 53% of the original sample. Across time, depressive symptoms decreased significantly; however, a decreased score was strongly related to number of negative life events. Social support scores were minimally related to depressive symptomatology. Service recommendations based on these findings include conducting third-trimester assessments of life events experienced during the past year and screening for depression to better identify women at risk of late pregnancy to postpartum–persistent depressive symptoms. More research and clinical attention on dysphoric states in pregnant Latinas and understanding the consequences of impaired perinatal mental health on maternal well-being and infant outcomes are needed.

Women's knowledge and experience of atypical Pap results in a high risk community

We sought to describe the knowledge of, understanding of, and follow-up after atypical cervical cytology among low-income, urban women. Of 554 women who had an ASCUS or atypical Pap result in 1996,215 (39%) completed a telephone survey. Many (19%) had poor follow-up. Thirty percent of women denied ever being told of abnormal cytology; Spanish-speakers were more likely to be unaware (43.2% vs. 22.7%, p < .01) of abnormal cytology. Cancer fear was quite high, as were misconceptions regarding cause. Many women were unsatisfied with the information they received regarding their cytology.

Cartilage formation and calcification in arteries of mice lacking matrix Gla protein

Matrix Gla protein (MGP/Mgp) is a protein expressed predominantly by vascular smooth muscle cells (VSMCs) and by chondrocytes. Transgenic mice lacking Mgp die 1-3 months after birth due to calcification of elastic fibers and rupture of large elastic arteries such as the aorta. Here, we report on cartilage formation that commonly occurs in calcified arteries of Mgp-/- mice. Using histology, von Kossa staining, immunohistochemistry, and Western blotting, together with examination of cellular markers for VSMCs and extracellular matrix markers for cartilage, we provide evidence for cell transformation from VSMC to chondrocyte in the arterial media in the absence of Mgp. At 2 weeks of age in the aorta of Mgp-/- mice, VSMCs lose immunostaining for smooth muscle alpha-actin concomitant with the appearance of cartilage molecules as shown by immunohistochemical staining and Western blotting for aggrecan, link protein, and type II collagen. These data provide evidence that the absence of Mgp, and/or calcification of the ECM, in the arterial media can trigger chondrocyte differentiation and cartilage formation in blood vessels.

Osteopontin deficiency increases mineral content and mineral crystallinity in mouse bone

Fourier transform infrared microspectroscopy (FTIRM) and infrared imaging (FTIRI) were used to characterize the mineral in bones of two different lines of Opn-deficient (Opn-/-) mice and their background-matched wild-type controls (Opn+/+). Sections of tibia and femur from 12-week-old and 16-week-old mice were evaluated with a spatial resolution between 10 microm (FTIRM) and 7 microm (FTIRI). FTIRI was used to examine 400 microm x 400 microm areas in cortical bone and trabecular bone and FTIRM examined selected 20 microm x 20 microm areas at sites within these anatomically defined areas. Despite the absence of an obvious phenotype in Opn-deficient mice, being undetectable by radiographic and histological methods, FTIRM analyses revealed that the relative amount of mineral in the more mature areas of the bone (central cortical bone) of Opn-knockout mice was significantly increased. Moreover, mineral maturity (mineral crystal size and perfection) throughout all anatomic regions of the Opn-deficient bone was significantly increased. The 2-dimensional, color-coded data (images) produced by FTIRI showed similar increases in mineral maturity in the Opn-/- bone, however, the crystallinity parameters were less sensitive, and significance was not achieved in all areas analyzed. Nonetheless, the findings of increased mineral content and increased crystal size/perfection in both lines of Opn-deficient mice at both ages are consistent with in vitro data indicating that Opn is a potent inhibitor of mineral formation and mineral crystal growth and proliferation, and also support a role for Opn in osteoclast recruitment and function.

Homotypic interactions of soluble and immobilized osteopontin

Osteopontin (OPN) is an extracellular matrix protein found in bones and teeth, where it accumulates at matrix-matrix interfaces. We postulate that OPN interacts homotypically and heterotypically in the adhesion of apposing matrices. Using suspensions of OPN-coupled aldehyde/sulfate latex spheres, we measured the strength of homotypic OPN-OPN binding in vitro. Doublets formed through shear-induced collisions in a cone and plate rheoscope were subjected to shear stresses >0.6 Nm(-2) and the fraction broken up determined over 60 s. Rapid initial breakup of 35% of doublets was followed by very slow breakup of the remaining 65%. Monte Carlo simulation of the breakup kinetics pointed to the existence of low and high bond strength populations of doublets. Dynamic light scattering spectroscopy of soluble OPN showed that 27% by mass existed as dimers. We postulate that OPN dimers binding to monomers account for the low strength bonds since a strong bond has already formed between the molecules of the dimer. In contrast, OPN-OPN monomer bonds had higher tensile strength than bonds between the high-affinity interaction of IgG and protein G, previously studied. Antibody blocking studies showed that the self-binding region of OPN resides in the C-terminus. These data suggest that homotypic OPN-OPN bonds have physiologically significant strength, supporting the hypothesis that OPN-OPN binding and self-assembly participate in adhesion within mineralized tissues.

Depression and negative life events among pregnant African-American and Hispanic women

Depression, social support, and life events were assessed in a sample of African-American and Hispanic women (N = 148) with uncomplicated pregnancies. Over half (51%) showed elevated depressive symptoms. Overall, women had fewer social supports and more negative life events than found in previous studies. African-Americans had more practical social support and persons in their support networks than Hispanics. Over a third of the sample (37%) had lost an important person in the past year. Depressed women reported more negative events than nondepressed women. Many negative life events and few social supports place minority women at risk for prenatal depression.

Interobserver and intraobserver variation in the assessment of the healing of tibial fractures after intramedullary fixation

The reliability of the radiological assessment of the healing of tibial fractures remains undetermined. We examined the inter- and intraobserver agreement of the healing of such fractures among four orthopaedic trauma surgeons who, on two separate occasions eight weeks apart, independently assessed the radiographs of 30 patients with fractures of the tibial shaft which had been treated by intramedullary fixation. The radiographs were selected from a database to represent fractures at various stages of healing. For each radiograph, the surgeon scored the degree of union, quantified the number of cortices bridged by callus or with a visible fracture line, described the extent and quality of the callus, and provided an overall rating of healing. The interobserver chance-corrected agreement using a quadratically weighted kappa (kappa) statistic in which values of 0.61 to 0.80 represented substantial agreement were as follows: radiological union scale (kappa= 0.60); number of cortices bridged by callus (kappa = 0.75); number of cortices with a visible fracture line (kappa= 0.70); the extent of the callus (kappa = 0.57); and general impression of fracture healing (kappa = 0.67). The intraobserver agreement of the overall impression of healing (kappa = 0.89) and the number of cortices bridged by callus (kappa = 0.82) or with a visible fracture line (kappa = 0.83) was almost perfect. There are no validated scales which allow surgeons to grade fracture healing radiologically. Among those examined, the number of cortices bridged by bone appears to be a reliable, and easily measured radiological variable to assess the healing of fractures after intramedullary fixation.

The use of a blade plate and autogenous cancellous bone graft in the treatment of ununited fractures of the proximal humerus

Stable internal fixation is essential to obtain healing of an ununited fracture of the proximal humerus. Standard plate and screw fixation may be inadequate to secure a small, osteopenic proximal fragment. We used blade plates and autogenous cancellous bone graft to repair ununited fractures of the proximal humerus in 25 patients (19 women and 6 men) with a mean age of 61 years. Healing was documented in 23 of 25 patients (92%). Objective and subjective instruments documented substantial functional improvement in patients with healed fractures. The results were classified as good or excellent in 20 of 25 patients, and few complications were encountered. Blade plate fixation facilitates successful treatment of ununited fractures of the proximal humerus.

Ovocalyxin-32, a novel chicken eggshell matrix protein. isolation, amino acid sequencing, cloning, and immunocytochemical localization

The eggshell is a highly ordered structure resulting from the deposition of calcium carbonate concomitantly with an organic matrix upon the eggshell membranes. Mineralization takes place in an acellular uterine fluid, which contains the ionic and matrix precursors of the eggshell. We have identified a novel 32-kDa protein, ovocalyxin-32, which is expressed at high levels in the uterine and isthmus regions of the oviduct, and concentrated in the eggshell. Sequencing of peptides derived from the purified protein allowed expressed sequence tag sequences to be identified that were assembled to yield a full-length composite sequence whose conceptual translation product contained the complete amino acid sequence of ovocalyxin-32. Data base searches revealed that ovocalyxin-32 has limited identity (32%) to two unrelated proteins: latexin, a carboxypeptidase inhibitor expressed in the rat cerebral cortex and mast cells, and a skin protein, which is encoded by a retinoic acid receptor-responsive gene, TIG1. High level expression of ovocalyxin-32 was limited to the isthmus and uterus tissue, where immunocytochemistry at the light and electron microscope levels demonstrated that ovocalyxin-32 is secreted by surface epithelial cells. In the eggshell, ovocalyxin-32 localizes to the outer palisade layer, the vertical crystal layer, and the cuticle of the eggshell, in agreement with its demonstration by Western blotting at high levels in the uterine fluid during the termination phase of eggshell formation. Ovocalyxin-32 is therefore identified as a novel protein synthesized in the distal oviduct where hen eggshell formation occurs.

Tardy posterolateral rotatory instability of the elbow due to cubitus varus

BACKGROUND

Cubitus varus has long been considered merely a cosmetic deformity. The purpose of this paper is to demonstrate a causal relationship between cubitus varus and instability of the elbow.

METHODS

In twenty-four patients (twenty-five limbs) with a cubitus varus deformity following a pediatric distal humeral fracture or resulting from a congenital anomaly (three limbs of two patients), tardy posterolateral rotatory instability of the elbow developed approximately two to three decades after the deformity occurred. All patients presented with lateral elbow pain and recurrent instability. The average varus deformity was 15 degrees (range, 0 degrees to 35 degrees ). Surgery was performed in twenty-one patients (twenty-two limbs). Treatment consisted of reconstruction of the lateral collateral ligament and osteotomy in seven limbs, ligament reconstruction alone in ten, osteotomy alone in four, and total elbow arthroplasty in one.

RESULTS

In three patients, the triceps muscle was dynamically stimulated intraoperatively to contract while resisting extension of the elbow. This produced posterolateral rotatory subluxation of the elbow, which was reversed by corrective osteotomy and lateral transposition of a portion of the medial head of the triceps that originally had been attached to the elongated, deformed medial aspect of the olecranon. At an average of three years (minimum, one year) after the operation, the result was good or excellent for nineteen of the twenty-two limbs that had undergone an operation; three limbs had persistent instability.

CONCLUSIONS

With cubitus varus, the mechanical axis, the olecranon, and the triceps line of pull are all displaced medially. The repetitive external rotation torque on the ulna permitted by these deformities can stretch the lateral collateral ligament complex and lead to posterolateral rotatory instability. Thus, cubitus varus deformity secondary to supracondylar malunion or congenital deformity of the distal part of the humerus may not always be a benign condition and may have important long-term clinical implications. Operative correction can relieve symptoms of instability. The indications for preventive corrective osteotomy remain to be determined.

Predictors of follow-up of atypical and ASCUS papanicolaou tests in a high-risk population

OBJECTIVE

Our goals were to assess adherence to the National Cancer Institute clinical practice guideline for the management of atypical squamous cells of uncertain significance (ASCUS) Papanicolaou (Pap) test results in a community at high risk of cervical cancer. We also hoped to identify predictors of adherence to the guideline.

STUDY DESIGN

We used an historical cohort and collected data by chart abstraction.

POPULATION

Our study included women receiving care in 7 urban community health centers who had an initial ASCUS or atypical Pap test result in 1996. We excluded women with a history of cervical dysplasia or human immunodeficiency virus infection, yielding a final sample of 387 women.

OUTCOMES

measured The outcome measured was the level of adherence to the guideline, defined as falling within 1 of 3 mutually exclusive categories (complete, moderate, or low).

RESULTS

Care providers recommended colposcopy after an initial atypical Pap test result in 12% of cases and repeat cytology in 67%. Failure to document a plan for management was found in 19% of cases. Complete adherence was achieved for 27% of subjects, moderate adherence for 28%, and low adherence for 45%. The factors associated with complete versus moderate or low adherence included site of care, description of the abnormality (ASCUS vs atypia), availability of on-site colposcopy, and discussing the plan at a visit.

CONCLUSIONS

Adherence with the National Cancer Institute clinical practice guideline in this setting was disappointing and varied substantially by site. Factors amenable to change that may improve follow-up include good communication of results with patients and providing colposcopy at the site of primary care.

The long-term functional outcome of operatively treated tibial plateau fractures

OBJECTIVES

To review the long-term functional results of the surgical treatment of tibial plateau fractures using standard techniques of open reduction and internal fixation.

DESIGN

Retrospective study.

SETTING

University hospital.

METHODS

Forty-seven displaced fractures of the tibial plateau in forty-six patients were treated with open reduction, interfragmental screw fixation of the articular fragments, and buttress plate fixation and had a minimum of five years of follow-up. All aspects of their care, including tibial plateau fracture type, operative management and associated injuries, were documented. Preoperative and postoperative follow-up radiographs were analyzed for fracture classification and adequacy of reduction. All patients were contacted and given functional outcome questionnaires using both a generic health status scale (Short Form 36 [SF-36]) (18) and a disability scale relating to knee osteoarthritis (Western Ontario and McMaster Universities Osteoarthritis index [WOMAC]) (1). Data were also collected regarding return to work and sporting activities. Assessment scores were analyzed with respect to age, fracture type and severity, and were compared to standardized age and sex-matched scores for the healthy population. The average age of the patients at the time of injury was forty years and the average follow-up period was 8.3 years. Of the forty-seven fractures studied, twenty-five were classified as Schatzker types I, II, or III, and the remaining twenty-two were types IV, V, or VI (15). All fractures received operative treatment within forty-eight hours and all but five fractures were acceptably reduced.

RESULTS

Compared to the standardized SF-36 categorical and aggregate scores, there was no statistically significant difference between the healthy age-matched population and twenty-four of twenty-six of the under-age-forty group regardless of fracture type. With regard to the over-age-forty group, scores statistically similar to the control population were found in only twelve of twenty-one patients. Although there was a large variance in WOMAC scores for all groups resulting in no statistically significant difference being found, a trend toward higher categorical and aggregate scores was seen with increasing age at presentation. There was no correlation between WOMAC scores and fracture type. Multiple-classifications analysis of all data revealed that presentation age was the most significant source of variation with respect to functional outcome. Fracture type had much less influence and adequacy of reduction had no significant influence on outcome, although the group of patients having an inadequate reduction by the authors' criteria was too small in number to reasonably comment upon.

CONCLUSIONS

Open reduction and internal fixation is a satisfactory technique for the treatment of displaced fractures of the tibial plateau, particularly for patients younger than forty years.

Osteopontin

Osteopontin (OPN) is a highly phosphorylated sialoprotein that is a prominent component of the mineralized extracellular matrices of bones and teeth. OPN is characterized by the presence of a polyaspartic acid sequence and sites of Ser/Thr phosphorylation that mediate hydroxyapatite binding, and a highly conserved RGD motif that mediates cell attachment/signaling. Expression of OPN in a variety of tissues indicates a multiplicity of functions that involve one or more of these conserved motifs. While the lack of a clear phenotype in OPN "knockout" mice has not established a definitive role for OPN in any tissue, recent studies have provided some novel and intriguing insights into the versatility of this enigmatic protein in diverse biological events, including developmental processes, wound healing, immunological responses, tumorigenesis, bone resorption, and calcification. The ability of OPN to stimulate cell activity through multiple receptors linked to several interactive signaling pathways can account for much of the functional diversity. In this review, we discuss the structural features of OPN that relate to its function in the formation, remodeling, and maintenance of bones and teeth.