Improved osseointegration of PTFEP-coated titanium implants.

BACKGROUND: Clinical success of bone implants is critically related to the interaction between the implant surface and the surrounding tissue. The polymer poly(bis(trifluoroethoxy)phosphazene) (PTFEP) is a promising, highly biocompatible surface coating which also inhibits the adsorption of granulocytes, macrophages, inflammatory cells, bacteria, and platelets. However, there is limited clinical experience of PTFEP as a coating for bone implants. Therefore PTFEP-coated titanium implants in an animal model were examined. MATERIAL/METHODS: PTFEP-coated titanium cylinders were implanted into the lateral femoral condyles of rabbits. Osseointegration was examined six weeks and six months after implantation using a non-destructive mechanical pull-out measurement and a histological analysis. RESULTS: The results indicate improved osseointegration of PTFEP-coated implants. Six weeks after implantation, the PTFEP-coated implants showed a higher stiffness (pull-out length [pol]=7.1+/-2.0 microm) compared with uncoated cylinders (pol=10.2+/-3.4 microm, p<0.05). Six months after implantation, the mechanical properties of both implants had adjusted, and histological analysis revealed an increased bone-implant interface of PTFEP-coated cylinders compared with the first 6 weeks (17.5% vs. 8.2% in controls, p<0.05). CONCLUSIONS: Taken together, the results of this preliminary study indicate promising applications of PTFEP as a coating material for bone implants.

Influence of professional dance training on peak torque and proprioception at the ankle.

OBJECTIVE: To investigate the influence of professional dance training on the peak torque ratio of plantar flexion to dorsiflexion (PF/DF), angle replication ability, and balance in comparison to age-matched and gender-matched controls. The effects of injuries sustained before and during the study time period were also assessed. DESIGN: Prospective age-matched and gender-matched nonrandomized intervention study. SETTING: Premises of the Orthopedic University Hospital, Heidelberg, where measuring apparatus belonging to the hospital was used for the tests. PARTICIPANTS: One group of 42 dancers (31 female, 11 male) in professional training (State Academy) and 40 age-matched and gender-matched controls with no prior dance or specific sport training. MAIN OUTCOME MEASUREMENTS: Isokinetic tests for peak torque at 30 degrees /s and 120 degrees /s, a passive angle-replication test (Biodex system 3), and a test of 1-legged standing were each carried out on 2 measurement dates (M1, M2): at the beginning of a season of professional dance training (M1) and after 5 months of such training (M2). Symptoms and/or injuries sustained during this period were ascertained continuously by means of questionnaires and interviews. RESULTS: A significant increase in peak torque in PF was observed in both dancer groups and male controls between M1 and M2. A significant increase in PF/DF peak torque ratio at 30 degrees /s was observed in both male groups between M1 and M2. At M2, no significant differences in PF/DF peak torque ratio could be found between male dancers and controls, but at 30 degrees /s between the female groups. However, in both female groups, the PF/DF ratio was not found to increase significantly between M1 and M2. In the angle-replication and 1-legged standing test, no consistent improvement was observed between M1 and M2 in either dancers or controls. In the angle-replication test, there were no significant differences between dancers and controls at M2. In the 1-legged standing test, the dancers did significantly better than controls. A total of 7 ankle injuries were recorded, but no difference was found between injured and uninjured subjects in the proprioceptive tests either at M1, as the predicator, or at M2 as the residual. CONCLUSIONS: Dance training did not increase the peak torque ratio of PF/DF within 5 months, but a group difference was found between the women groups. Ballet training alone without concurrent additional coordinative training does not lead to improvements in ankle joint position sense or improved measures of balance within this period of observation.

Acute traumatic primary patellar dislocation: long-term results comparing conservative and surgical treatment.

OBJECTIVE: This report evaluates the subjective, clinical, and functional long-term results comparing surgical and conservative treatment in patients with a primary traumatic patellar dislocation. DESIGN AND SETTING: This retrospective clinical study focuses on patients with primary acute traumatic patellar dislocation. Patients with radiologic signs indicative of a predisposition for recurrent patellar instability were excluded from this study. PATIENTS: A total of 126 patients were examined a mean of 8.1 years after initial treatment of their primary patellar dislocation. INTERVENTIONS AND MAIN OUTCOME MEASUREMENTS: Patients were retrospectively divided into groups with conservative therapy (n = 63), diagnostic arthroscopy only (n = 20), immediate surgical reconstruction of the parapatellar ligament complex (n = 37), and refixation of osteochondral fragments (n = 6). Redislocation and resurgery rate, activity level, and subjective, clinical, and functional results were evaluated in these patients, and the outcomes in these groups were compared. RESULTS: In the long term, functional results (as expressed in the Lysholm score) were excellent or good in 85% of the patients, and good subjective results were reported by 71%, but follow-up revealed a recurrence rate of 26% in the total study population. The high activity level before the initial trauma could not be completely regained after treatment. There was no significant difference between the surgically and conservatively treated groups in the redislocation and reoperation rates, level of activity, or functional and subjective outcomes. CONCLUSIONS: Even with a focus on acute traumatic etiology and when factors predisposing to recurrent instability are largely excluded, the redislocation rate after treatment of acute patellar dislocation is still high, despite good clinical and subjective results. Conservative management seems to be the treatment of choice in patients with acute patellar dislocation, provided that the generally accepted indications for surgery, such as evidence of osteochondral fragments and major defects of the parapatellar ligament complex, are given due consideration.

Adenovirus-mediated gene transfer of growth and differentiation factor-5 into tenocytes and the healing rat Achilles tendon.

Growth and differentiation factor-5 (GDF-5) is known to induce tendon tissue and stimulate tendon healing. The hypothesis was that adenoviral GDF-5 transfer leads to transitory transgene expression and improves Achilles tendon healing. In vitro experiments were first performed with rat tenocytes. Transgene expression was evaluated by RT-PCR, Western blotting and GDF-5-ELISA. In vivo virus dosage and transgene expression were examined by a marker gene transfer (LacZ and luciferase). In the main experiment in 131 rats, adenovirus particles (3 x 10(10)) were injected into transected Achilles tendons. The time course of GDF-5 mRNA expression was assessed by real-time RT-PCR. Histology and biomechanical testing were used to evaluate tendon healing and tensile strength. In vitro GDF-5 was secreted with a maximum after 2 weeks (330 ng GDF-5/10(6) cells per 24 hr). In vivo GDF-5 transgene expression showed a maximum at 4 weeks. At 8 weeks, GDF-5 specimens were thicker (p<0.05) with a trend to higher strength (p=0,064). Histology showed greater cartilage formation in type II collagen stains than in controls. Injection of adenovirus particles successfully can deliver the GDF-5 gene in healing tendons and leads to thicker tendon regenerates after 8 weeks. This technique might become a new approach for nonsurgical treatment of tendon injuries.

Ankle fusion attributable to posttraumatic arthrosis: a long-term followup of 48 patients.

The subjective, clinical, functional, and radiologic long-term results of 48 patients after tibiotalar arthrodesis done for posttraumatic and isolated arthrosis of the ankle are reported. After an average followup of 9.3 years, good and very good results were achieved in 92% for subjective parameters and in 73% for clinical and functional parameters as reflected in the American Orthopaedic Foot and Ankle Society ankle and hindfoot score. Fusion of the ankle in a position greater than 5 degrees plantar flexion was correlated with a worse late clinical outcome monitored by the American Orthopaedic Foot and Ankle Society ankle and hindfoot score. At the followup, average tarsal mobility in the surgically treated foot was reduced to 54% of the contralateral side and that loss of tarsal mobility led to a poorer clinical outcome. However, a high incidence of subsequent arthrosis in the adjacent joints of the foot seems not to be completely avoidable in the long-term. The subtalar joint had moderate and severe arthrosis in 47% of patients. Long-term outcome was worse in these patients compared with patients with mild or without degenerative changes in this joint. The current study justifies the value of ankle fusion as a surgical treatment option in patients with end-stage arthrosis in the ankle, provided precise intraoperative positioning of the arthrodesis and the importance of the subtalar joint, are given due consideration.