Berton R. Moed

Pilon fractures. Treatment protocol based on severity of soft tissue injury.

One hundred seven pilon fractures in 107 patients were treated according to a staged prospective protocol. All pilon fractures were stabilized immediately by the application of calcaneal traction. Open fractures or fractures in patients with multiple injuries were stabilized with traveling traction that was applied in the operating room. A distraction computed tomography scan was obtained before definitive treatment. Treatment groups were based on the degree of soft tissue compromise. Forty-one patients with Tscherne Grade 0 or Grade I injuries underwent open reduction and internal fixation (open plating) using contemporary techniques and low-profile implants. Sixty-four patients with Tscherne Grade II and Grade III closed injuries and all patients with open fractures underwent definitive treatment with limited open reduction and stabilization using small wire circular external fixators. Clinical and radiographic evaluations were performed at an average 4.9 years after injury. For all fracture types (AO classification), 81% of the patients who were treated with external fixation and 75% of the patients who were treated with open plating had good or excellent results. For severe fracture patterns (Type C), patients in both groups had significantly poorer results than patients with Types A and B fractures. The patients in the open plating group had a significantly higher rate of nonunion, malunion, and severe wound complications compared with the patients who received external fixation for Type C fracture patterns. Because of the increased incidence of bony and soft tissue complications when treating open or closed Type C fractures, use of limited exposures and stabilization with small wire circular external fixators is recommended.

Timing of Wound Closure in Open Fractures Based on Cultures Obtained After Debridement

BACKGROUND The timing of wound closure in open fractures has remained an inexact science. Numerous recommendations have been made for the management of these injuries regarding the optimal time to perform competent wound closure, with all advice based on subjective parameters. The purpose of this study was to determine the utility of a prospective protocol with use of wound cultures obtained after irrigation and debridement as a guide to the timing of wound closure following an open fracture of an extremity. METHODS Four hundred and twenty-two open fractures had emergency irrigation and debridement, fracture stabilization, and open wound management. Wound cultures were obtained for aerobic and anaerobic analysis following debridement. At forty-eight hours after debridement, patients were again returned to surgery. If the initial culture results were positive, a repeat irrigation and debridement was carried out, and additional cultures were obtained after debridement. This procedure was repeated, and the wound was not closed until negative culture results were achieved. RESULTS Of the 422 open fractures, 346 were available for long-term follow-up. The overall deep infection rate was 4.3%. Gustilo Type-II fractures had a deep infection rate of 4%, and Type-III fractures had an infection rate of 5.7%. Type-III fractures demonstrated differences among the fracture patterns within this type, as infection developed in 1.8% of Type-IIIA injuries, 10.6% of Type-IIIB fractures, and 20% of Type-IIIC fractures. Fractures requiring multiple debridement procedures and those in patients with diabetes or an increased body mass index demonstrated higher rates of infection. With the numbers studied, fractures in which the wound was closed in the presence of positive cultures (a protocol breach) did not have a significantly increased risk of deep infection (p = 0.0501). CONCLUSIONS The use of this standardized protocol was shown to achieve a very low rate of deep infection compared with historical controls. An increased number of irrigation and debridement procedures are required to achieve this improved outcome. LEVEL OF EVIDENCE Therapeutic Level IV. See Instructions to Authors for a complete description of levels of evidence.

Excessive running induces cartilage degeneration in knee joints and alters gait of rats.

The goal of this study was to develop an aggressive running regimen for modeling osteoarthritis (OA) in rats. Twelve Wistar rats were randomly placed into either a running group or a non‐running group to serve as the control. The running rats used a motorized treadmill to run either 30 km in 3 weeks or 55 km in 6 weeks. Each week, the prints of hind paws were obtained when rats were made to walk through a tunnel. The resulting prints were digitalized for analyses of stride length and step angle. The histology of the knees was examined at 3 and 6 weeks and the OA pathology in the knees was quantified by Mankins score. Osteoarthritic pathology developed in the knees of the running rats, including decreased proteoglycan content, uneven type II collagen distribution in the cartilage matrix, increased MMP‐13 expression, expanded calcified cartilage zone, and clefts and defects in articular cartilage. The pathology worsened from running for 3 to 6 weeks. Gait analysis revealed an inverse correlation between paw angle and the grades of OA pathology. In conclusion, excessive running induces joint degeneration and a unique gait pattern in rats.

Distinct functionalities of bone morphogenetic protein antagonists during fracture healing in mice.

The bone morphogenetic protein (BMP) family of growth factors plays critical roles in bone formation. BMPs are regulated at multiple levels by various BMP antagonists. This study investigated how BMP antagonists are integrated into the cascade of events of bone formation during fracture healing. Forty mice underwent a controlled femur fracture; tissue samples at the fracture site were harvested at days 1, 3, 7, 14 and 21 after fracture, for quantification of the expression of BMPs and BMP antagonists. During fracture healing, BMP‐2, ‐4 and ‐7 were up‐regulated, but BMPR‐1A and BMPR‐2 showed reduced expression after day 14. Among BMP antagonists, the expressions of PRDC, SOST, Smad7, GREM1 and CERBERUS were generally down‐regulated during fracture healing. In contrast, Noggin was significantly up‐regulated in the first week after fracture; 7 days after fracture, other BMP antagonists, including DAN, CHRD, Smad6 and BAMBI, also showed significantly increased expression. In conclusion, this study indicates that BMP antagonists can be divided into two functional groups in relation to fracture healing: (1) those whose suppression may be essential for the initiation of osteogenesis; (2) those that are upregulated and may function in the remodeling of newly formed bone.

A proteomic approach for identification and localization of the pericellular components of chondrocytes

Although the pericellular matrix (PCM) plays a central role in the communication between chondrocytes and extracellular matrix, its composition is largely unknown. In this study, the PCM was investigated with a proteomic approach using chondrons, which are enzymatically isolated constructs including the chondrocyte and its surrounding PCM. Chondrons and chondrocytes alone were isolated from human articular cartilage. Proteins extracted from chondrons and chondrocytes were used for two-dimensional electrophoresis. Protein spots were quantitatively compared between chondron and chondrocyte gels. Cellular proteins, which had similar density between chondron and chondrocyte gels, did not proceed for analysis. Since chondrons only differ from chondrocytes in association of the PCM, protein spots in the chondron gels that had higher quantity than that in the chondrocyte gels were selected as candidates of the PCM components and processed for mass spectrometry. Among 15 identified peptides, several were fragments of the three type VI collagen chains (α-1, α-2, and α-3). Other identified PCM proteins included triosephosphate isomerase, transforming growth factor-β induced protein, peroxiredoxin-4, ADAM (A disintegrin and metalloproteinases) 28, and latent-transforming growth factor beta-binding protein-2. These PCM components were verified with immunohisto(cyto)chemistry for localization in the PCM region of articular cartilage. The abundance of type VI collagen in the PCM emphasizes its importance to the microenvironment of chondrocytes. Several proteins were localized in the PCM of chondrocytes for the first time and that warrants further investigation for their functions in cartilage biology.

Locked versus standard unlocked plating of the symphysis pubis in a Type-C pelvic injury: A cadaver biomechanical study

INTRODUCTION The benefits of locked plating for pubic symphyseal disruption have not been established. The purpose of this biomechanical study was to determine whether locked plating offers any advantage over conventional unlocked plating of the pubic symphysis in the vertically unstable, Type-C pelvic injury. METHODS In each of eight embalmed cadaver pelvis specimens, sectioning of the pubic symphysis in conjunction with a unilateral release of the sacroiliac, sacrospinous, and sacrotuberous ligaments and pelvic floor was performed to simulate a vertically unstable Type-C (Orthopaedic Trauma Association 61-C1.2) pelvic injury. The disrupted SI joint was then reduced and fixed using two 6.5mm cannulated screws inserted into the S1 body. Using a six-hole 3.5mm plate specifically designed for the symphysis pubis having both locked and unlocked capability, four pelvises were fixed with locked screws and four pelvises were fixed with standard unlocked bicortical screws. Both groups were similar based on a dual-emission X-ray absorptiometry evaluation (P=0.69). Each pelvis was then mounted on a servohydraulic materials-testing apparatus using a bilateral stance model to mainly stress the symphyseal fixation and was cycled up to 1 million cycles or failure, whichever occurred first. RESULTS Five specimens experienced failure at the jig mounting/S1 vertebral body interface, occurring between 360,000 and 715,000 cycles. Frank failure of the anterior or posterior instrumentation did not occur. However, end-trialing diastasis of the initial pubic symphysis reduction was found in all pelvises. There were no differences between the groups with respect to this loss of symphyseal reduction (P=0.69) or average cycles to failure (P=1.0). CONCLUSION Pubic symphyseal locked plating does not appear to offer any advantage over standard unlocked plating for a Type-C (OTA 61-C1.2) pelvic ring injury.

Ligamentous contributions to pelvic stability in a rotationally unstable open-book injury: A cadaver study

INTRODUCTION Due to the orientation of the sacroiliac joint (SIJ), as the symphysis widens in an open-book pelvic ring disruption, it should displace inferiorly. The purposes of this study were to reconfirm this inferior displacement and to evaluate the relative contributions of the pubic symphysis (PS), the sacrotuberous/sacrospinous ligament complex (STL/SSL) and the anterior sacroiliac ligament (ASIL) to pelvic ring stability in a rotationally unstable open-book injury. METHODS For each of 6 cadaver pelves, the right hemipelvis was fixed to a table and the PS was sectioned. Under fluoroscopy, a manual external rotational force was then applied through the unfixed, left ilium. At the point of maximal displacement, a permanent AP image was obtained. With magnification corrected, horizontal (H) and vertical (V) displacements were measured. The pelves were then divided into two groups of three each. In Group 1, the PS release was followed by sectioning of the STL/SSL, and then the ASIL. In Group 2, the PS release was followed by sectioning of the ASIL and then the STL/SSL. The above described technique of manual manipulation and radiographic measurement was repeated after each stage of ligament release. RESULTS The displacement after initial PS sectioning was not significantly different when comparing Group 1 to Group 2. In both groups, a significant and progressive increase in displacement was noted when the PS (H and V; p<0.05) and ASIL (H and V; p<0.05) were sectioned. However, there was no significant change with SSL/STL sectioning in either group. Vertical displacements were all directed inferiorly. CONCLUSIONS The PS and ASIL are important in maintaining pelvic ring external rotational stability. However, the SSL/STL has little, if any, effect in this regard. Due to the orientation of the SIJ, external rotation of the hemipelvis, as in open-book injury, will show inferior vertical, as well as horizontal, displacement on the AP radiograph, despite the PSIL being intact.

Distinct phenotypes and regenerative potentials of early endothelial progenitor cells and outgrowth endothelial progenitor cells derived from umbilical cord blood.

The capability of postnatal neovascularization makes circulating endothelial progenitor cells (EPCs) promising for regenerative medicine and tissue engineering. Using EPCs isolated from umbilical cord blood, this study aimed to clarify the transition of functional properties from early EPCs (e‐EPCs) to outgrowth EPCs (og‐EPCs) for potential applications in regenerative medicine. Mononuclear cells were collected from umbilical cord blood via density gradient centrifugation and further negatively selected by CD45. EPCs were sorted from mononuclear cells by the expression of CD34. e‐EPCs (7 days of culture) and og‐EPCs (3 weeks of culture) were characterized by morphology, intake of acetylated low‐density lipoprotein, vessel‐cord formation, cell surface phenotype and the expression of angiogenic genes. e‐EPCs and og‐EPCs were also compared for osteogenic differentiation under the stimulation of BMP‐2. Chemotaxis by SDF‐1 was compared among og‐EPCs and the first‐ and second‐day attached e‐EPCs. Based on the expression of angiogenic genes, e‐EPCs possessed few angiogenic properties in vitro and og‐EPCs were angiogenic. e‐EPCs, however, expressed significant CXCR4 and migrated toward the SDF‐1 gradient. og‐ECPs did not express CXCR4 and showed no response to SDF‐1. During culture, gaining an angiogenic phenotype by og‐EPCs is associated with the loss of homing potential. These contrast properties determine different potentials of e‐EPCs and og‐EPCs in regenerative medicine. Copyright

Can Computed Tomography Predict Hip Stability in Posterior Wall Acetabular Fractures

BackgroundIn a pilot study, two-dimensional (2-D) CT assessment of posterior wall fracture fragments predicted hip stability with small fracture fragments and instability for large fracture fragments.Questions/purposesTo confirm the previous findings, we determined whether there is sufficient observer consistency and accuracy to predict hip stability in posterior wall acetabular fractures for this CT assessment method and assessed its ease of clinical use.MethodsWe selected 10 fractures having variable characteristics with known clinical outcome and created three study participant groups, based on level of training, for evaluation. Each observer reviewed the CT scans from the 10 fractures and applied the method in two separate sessions, the second after at least a 1-month washout period.ResultsParticipants reported subjective ease in using the method, averaging 5 minutes (range, 3–11 minutes) for each assessment. Intraobserver and interobserver reliability were both greater than 0.80 regardless of the level of experience. Although sensitivity was 90%, specificity was only 61% after comparison with examination under anesthesia (EUA). Inappropriate nonoperative treatment would have occurred in 6% of cases and inappropriate operative treatment in 16%.ConclusionsThis method for assessing hip instability is reliable, reproducible, and easy to learn and use. However, as a diagnostic tool in the clinical setting, it is useful only for fractures involving greater than 50% of the posterior wall owing to limited accuracy. For fractures less than 50%, EUA should be performed to determine hip stability.

Expression profile of carbonic anhydrases in articular cartilage

Carbonic anhydrases (CAs), which catalyze the reversible reaction of carbonate hydration, are important for cartilage homeostasis. The full spectrum of CA activity of all 13 isoenzymes in articular cartilage is unknown. This study quantified the mRNA profile of CAs in rat articular cartilage, using quantitative polymerase chain reactions. Among the 13 functional CAs, CAs II, III, Vb, IX, XII and XIII were significantly expressed at mRNA level by the chondrocytes in articular cartilage. To verify these significantly expressed CAs in articular cartilage at protein level, immunohistochemistry was performed. While CAs III, Vb and XII distributed in the full-thickness of cartilage, including the calcified zone of cartilage, CA II was mainly localized in the proliferative zone of cartilage. CA IX was limited in the superficial zone of cartilage and CA XIII expressed in the superficial and partially mid zone. These results provide a framework for understanding individual CAs as well as the integrated CA family in cartilage biology, including matrix mineralization.