Peter Kloen

BMP signaling components are expressed in human fracture callus

Of the various growth factors involved in the healing response after a fracture, bone morphogenetic proteins (BMPs) are emerging as key modulators. BMPs exert their effects by binding to a complex of type I and type II receptors leading to the phosphorylation of specific downstream effector proteins called Smads. The current study examined the presence of BMP signaling components in human callus obtained from five nascent malunions undergoing fracture fixation. These callus samples represented various stages of bone healing and a mixture of endochondral and intramembraneous bone healing. We performed immunohistochemistry on the callus, using antibodies for BMP (BMP-2,-3,-4,-7), their receptors (BMPR-IA, -IB, -II), and phosphorylated BMP receptor-regulated Smads (pBMP-R-Smads). Active osteoblasts showed fairly consistent positive staining for all BMPs that were examined, with the immunoreactivity most intense for BMP-7 and BMP-3. Immunostaining for BMPs in osteoblasts appeared to colocalize with the expression of BMPR-IA, -IB, and -II. Positive immunostaining for pBMP-R-Smads suggests that the BMP receptors expressed in these cells are activated. Staining for BMPs in cartilage cells was variable. The immunostaining appeared stronger in more mature cells, whereas staining for BMP receptors in cartilage cells was less ubiquitous. However, the expression of pBMP-R-Smads in cartilage cells suggests active signal transduction. Fibroblast-like cells also had a variable staining pattern. Overall, our findings indicate the presence of BMPs, their various receptors, and activated forms of receptor-regulated Smads in human fracture callus. To the best of our knowledge, this is the first study that documents the expression of these proteins in human fracture tissue. Complete elucidation of the roles of BMP in bone formation will hopefully lead to improved fracture healing care.

Two and three-dimensional computed tomography for the classification and management of distal humeral fractures. Evaluation of reliability and diagnostic accuracy.

BACKGROUND Complex fractures of the distal part of the humerus can be difficult to characterize on plain radiographs and two-dimensional computed tomography scans. We tested the hypothesis that three-dimensional reconstructions of computed tomography scans improve the reliability and accuracy of fracture characterization, classification, and treatment decisions. METHODS Five independent observers evaluated thirty consecutive intra-articular fractures of the distal part of the humerus for the presence of five fracture characteristics: a fracture line in the coronal plane; articular comminution; metaphyseal comminution; the presence of separate, entirely articular fragments; and impaction of the articular surface. Fractures were also classified according to the AO/ASIF Comprehensive Classification of Fractures and the classification system of Mehne and Matta. Two rounds of evaluation were performed and then compared. Initially, a combination of plain radiographs and two-dimensional computed tomography scans (2D) were evaluated, and then, two weeks later, a combination of radiographs, two-dimensional computed tomography scans, and three-dimensional reconstructions of computed tomography scans (3D) were assessed. RESULTS Three-dimensional computed tomography improved both the intraobserver and the interobserver reliability of the AO classification system and the Mehne and Matta classification system. Three-dimensional computed tomography reconstructions also improved the intraobserver agreement for all fracture characteristics, from moderate (average kappa [kappa2D] = 0.554) to substantial agreement (kappa3D = 0.793). The addition of three-dimensional images had limited influence on the interobserver reliability and diagnostic characteristics (sensitivity, specificity, and accuracy) for the recognition of specific fracture characteristics. Three-dimensional computed tomography images improved intraobserver agreement (kappa2D = 0.62 compared with kappa3D = 0.75) but not interobserver agreement (kappa2D = 0.24 compared with kappa3D = 0.28) for treatment decisions. CONCLUSIONS Three-dimensional reconstructions improve the reliability, but not the accuracy, of fracture classification and characterization. The influence of three-dimensional computed tomography was much more notable for intraobserver comparisons than for interobserver comparisons, suggesting that different observers see different things in the scans-most likely a reflection of the training, knowledge, and experience of the observer with regard to these relatively uncommon and complex injuries.

Open Reduction and Internal Fixation of Delayed Unions and Nonunions of Fractures of the Distal Part of the Humerus

Background: The purpose of the present retrospective study was to evaluate the results of open reduction and internal fixation of delayed unions and nonunions of fractures of the distal part of the humerus.Methods: Between 1976 and 2001, fifty-two patients with a delayed union (thirteen patients) or nonunion (thirty-nine patients) of the distal part of the humerus were treated with open reduction and internal fixation along with selective elbow joint arthrolysis and bone-grafting. The average time to presentation was eighteen months (range, two to 192 months) after the injury. Thirty-nine of the fifty-two patients had undergone an average of 1.6 previous operations. There were twenty-seven supracondylar, six transcondylar, thirteen intercondylar, two lateral condylar, and four medial condylar delayed unions or nonunions. The average duration of follow-up was thirty-three months (range, three to 198 months).Results: Fifty-one of the fifty-two patients had healing of the delayed union or nonunion after the index operation; the average time to union was six months (range, two to twenty-four months). The average range of elbow motion increased from 71° preoperatively to 94° postoperatively. Complications included two superficial infections, two deep infections, and five cases of ulnar neuropathy. Fifteen patients (29%) needed additional surgery after the index procedure. Specifically, seven patients underwent removal of prominent hardware; six underwent hardware removal along with excision of heterotopic bone, ulnar neurolysis, and/or manipulation under anesthesia; one underwent irrigation and débridement; and one underwent compartment release.Conclusions: Open reduction through an extensile exposure and rigid internal fixation consistently results in healing of a delayed union or nonunion of the distal part of the humerus. An improved range of motion of the elbow can be achieved by securing the site of the nonunion and performing aggressive elbow joint arthrolysis and soft-tissue releases in patients with severe contractures.Level of Evidence: Therapeutic study, Level IV (case series [no, or historical, control group]). See p. 2 for complete description of levels of evidence.

Surgical treatment of intra-articular fractures of the distal part of the humerus: Functional outcome after twelve to thirty years

BACKGROUND The short-term results of open reduction and internal fixation of intra-articular distal humeral fractures are good to excellent in approximately 75% of patients, but the long-term results have been less well studied. This investigation addressed the long-term clinical and radiographic results of surgical treatment of intra-articular distal humeral fractures (AO Type C) as assessed with use of standardized outcome measures. METHODS Thirty patients were evaluated at an average of nineteen years (range, twelve to thirty years) after open reduction and internal fixation of a fracture of the distal part of the humerus to assess the range of elbow motion and the functional outcome. Twenty patients had an olecranon osteotomy, and all had fixation with plates and/or screws and/or Kirschner wires. No ulnar nerve was transposed. RESULTS Excluding one elbow salvaged with an arthrodesis and counted as a poor result, the average final flexion arc was 106 degrees and the average pronation-supination arc was 165 degrees. The average American Shoulder and Elbow Surgeons (ASES) score was 96 points, with an average satisfaction score of 8.8 points on a 0 to 10-point visual analog scale. The average Disabilities of the Arm, Shoulder and Hand (DASH) score was 7 points, and the average Mayo Elbow Performance Index (MEPI) score was 91 points. Including the patient with the arthrodesis, the final categorical ratings were nineteen excellent results, seven good results, one fair result, and three poor results. The presence of arthrosis did not appear to correlate with pain or predict disability or function. Subsequent procedures were performed in twelve patients (40%). CONCLUSIONS The long-term results of open reduction and internal fixation of AO-Type-C fractures of the distal part of the humerus are similar to those reported in the short term, suggesting that the results are durable. Functional ratings and perceived disability were predicated more on pain than on functional impairment and did not correlate with radiographic signs of arthrosis.

Lipoma arborescens of the knee

Lipoma arborescens is a rare intra-articular lesion, characterised by diffuse replacement of the subsynovial tissue by mature fat cells, producing prominent villous transformation of the synovium. The aetiology of this benign condition is unknown. We describe six cases involving the knee, discussing the symptoms, diagnosis and treatment.

Biomechanical and Clinical Evaluation of Posterior Malleolar Fractures. A Systematic Review of the Literature

INTRODUCTION Ankle fractures often have involvement of the posterior malleolus. Treatment guidelines exist based on limited biomechanical evidence and still is considered controversial. The objective of this article is to review the biomechanical literature concerning changes in tibiotalar contract area, changes in contact pressures, changes in ankle stability and incongruency of the joint after a posterior malleolar ankle fracture, and to review the clinical literature concerning the outcome of operative and nonoperative treatment of these fractures. Ultimately, the goal is to try to formulate helpful recommendations for clinical practice. MATERIAL The databases Pubmed/Medline, Cochrane Database of Systematic Reviews, Cochrane Clinical Trial Register, and Embase were searched from 1988 to November 2007 to identify studies relating to changes in tibiotalar contact area, contact pressures, ankle stability, clinical outcome, and radiographic osteoarthritis after a posterior malleolar fracture. The search was restricted to articles written in the English, German, and Dutch language. RESULTS Eight biomechanical studies, involving 96 cadaveric ankles were included and 10 clinical studies, involving 447 fractured ankles, were included. DISCUSSION No consensus in the literature was found as to which fragment size of the posterior malleolus (=posterior tibial margin) should be internally fixed. This is partially because of the lack of standardization in examining functional outcomes, making it difficult to compare results. It is not the peak pressure or changes in tibiotalar contact area, but rather the changes in peak pressure distribution that play a large role in posttraumatic arthritis development. It seems important to restore the medial and lateral constraints of the ankle because these, rather than the articular surfaces, provide the majority of ankle stability after an ankle fracture involving the posterior malleolar ankle fracture.

Open reduction and internal fixation of humeral nonunions : a biomechanical and clinical study.

Background: Several studies have compared different methods for fixation of the midpart of the humeral shaft, but there are only scattered data regarding which type of plate construct provides the best fixation for humeral nonunion. The objectives of this study were (1) to obtain objective data on the performance of four different plate constructs used for fixation of humeral nonunion, and (2) to report our clinical experience with plate fixation of thirty-seven nonunions of the midpart of the humeral shaft.Methods: In the first part of the study, four plate constructs were compared in a Sawbones model. The groups consisted of (1) a posterior limited-contact dynamic compression plate alone; (2) a posterior limited-contact dynamic compression plate and an interfragmentary screw; (3) a posterior limited-contact dynamic compression plate, a lateral 3.5-mm reconstruction plate, and an interfragmentary screw; and (4) a posterior limited-contact dynamic compression plate and a lateral 3.5-mm reconstruction plate. Tests were performed with use of an MTS Bionix machine in anterior-posterior four-point bending, medial-lateral four-point bending, and external rotation torque.In the second part of the study, the charts of thirty-seven consecutive patients in whom a nonunion of the midpart of the humeral shaft had been treated with plate fixation were reviewed retrospectively. The average age of the patients was forty-eight years (range, thirteen to seventy-eight years). Nineteen patients were treated with a single posterior plate, and eighteen were treated with a two-plate construct with the plates parallel and lying at 90° to each other. All of the nonunions were treated with bone-grafting, and an interfragmentary screw was used in thirty-six of the thirty-seven patients. Radiographs and the clinical status were evaluated at an average of thirteen months postoperatively.Results: The biomechanical testing showed that the two-plate constructs were significantly stiffer than the single-plate constructs in all test modes (p < 0.05). In the clinical part of the study, thirty-four (92%) of the nonunions healed without complications at an average of 4.8 months. Two nonunions treated with the two-plate construct and one treated with one plate failed to heal.Conclusions: No significant difference in the healing rate was found between the two clinical groups (p = 0.4, &bgr; = 0.9), and the overall healing rate was 92%. However, a two-plate construct with the plates at right angles is mechanically stiffer than a single-plate construct, which might be helpful if rigid stabilization of the humerus at the midshaft level is needed.

Anteroinferior plating of midshaft clavicular nonunions.

Many different techniques have been reported for the treatment of clavicular nonunions. Those techniques involving screws and plate generally position the plate on the superior (subcutaneous) surface of the clavicle. To decrease the risk of screw pull-out and prominence of the instrumentation, we currently perform anteroinferior plating using a 3.5-millimeter pelvic reconstruction plate with a lag screw and bone graft. A consecutive group of twelve patients with midshaft clavicular nonunions was treated with this technique. All nonunions united after an average of 3.6 months (range 2 to 8 months). All patients regained full function and mobility of the shoulder. The technique as described in this article illustrates a successful modification of the traditional plating technique of midshaft clavicular nonunions. We conclude that anteroinferior plating is a reliable and safe technique that leads to high rates of bony union in midshaft clavicular nonunions.

Clinical Evaluation of Locking Compression Plate Fixation for Comminuted Olecranon Fractures

BACKGROUND In patients managed with plate fixation for the treatment of an olecranon fracture, the placement of an axial intramedullary screw may obstruct the placement of bicortical screws in the ulnar shaft. To overcome this problem, unicortical screws can be applied with use of a contoured locking compression plate. The present study was designed to assess the effectiveness of this fixation method. METHODS Nineteen consecutive patients with an acute comminuted olecranon fracture were managed with a contoured locking compression plate and intramedullary screw fixation. Sixteen patients were available for follow-up at a minimum of twelve months after fixation. Patient-based outcomes were assessed, and patient satisfaction and pain were evaluated. RESULTS All nineteen fractures healed. The mean time to fracture union was four months. The mean Disabilities of the Arm, Shoulder and Hand score was 13. According to the Mayo Elbow Performance Index and the Broberg and Morrey grading system, fifteen of the sixteen patients with at least one year of follow-up had a good or excellent outcome. Nine patients underwent hardware removal at a mean of twelve months postoperatively. The mean elbow extension deficit in these patients improved significantly from 34 degrees to 10 degrees following hardware removal. The mean flexion improved from 118 degrees to 138 degrees , but this difference was not significant. CONCLUSIONS In the treatment of comminuted olecranon fractures, a contoured locking compression plate combined with an intramedullary screw provides sufficient stability for early postoperative functional rehabilitation, with an excellent fracture union rate and very good clinical outcomes.

Nonunions of the Distal Tibia Treated by Reamed Intramedullary Nailing

Objective: The purpose of this study is to determine the efficacy of reamed intramedullary nailing in the treatment of nonunions of the distal one-fourth of the tibia. Nonunions of the distal tibia are particularly difficult to treat given the short distal segment, the proximity to the ankle joint, and the fragile soft-tissue envelope. Intramedullary nailing is an attractive solution to this problem because it avoids extensive dissection, and the implant remains intraosseous, posing minimal problem for the soft tissues. Design: Retrospective review of patient charts and radiographs. Setting: Tertiary care orthopaedic hospital. Patients/Participants: Thirty-two patients with nonunions of the distal one-fourth of the tibia. Prior treatments included casting, internal fixation with plates and screws, intramedullary nailing, and external fixation. Seven patients had a history of infection, but no patient had signs of active infection at the time of surgery. Intervention: Study patients were treated by reamed, locked intra-medullary nailing. Main Outcome Measurements: Main outcome measurements included time to union, correction of deformity, and complications including infection and reoperation. Results: Average length of follow-up was 25 months (range 4–81 months). Twenty-nine out of 32 patients achieved union at an average of 3.5 months after reamed, locked intramedullary nailing. Of the remaining three, 2 patients united after dynamization (one at 4 months after dynamization and the other at 7 months), and the third patient united 4 months after exchange nailing. Deformity was corrected to a maximum of 4° in all planes. Four patients had positive intraoperative cultures, and only 2 required removal of the nail after achieving union to control infection. There were no signs of chronic osteomyelitis in these 2 patients at the date of the last follow-up visit; 5.5 years and 2 years following nail removal. Conclusions: Reamed, locked intramedullary nailing is a reliable and safe procedure in the treatment of nonunions in the distal one-fourth of the tibia, even in the setting of prior infection or external fixation. It allows for excellent correction of deformity, which is an essential component of the procedure.