The use of bone-graft substitutes in large bone defects: any specific needs?

INTRODUCTION

The gold standard for restoring bone defects is still considered to be autologous bone grafting. However, clinical benefits are not guaranteed and donor-site complications and morbidity is not infrequent. Research is on-going for the development of alternative bone substitutes of both biological and synthetic origin. The purpose of this study was to evaluate the type of materials used and their efficacy for the treatment of large bone defects in traumatology and orthopaedic surgery.

MATERIALS AND METHOD

A literature review was carried out of Embase and PubMed databases. Inclusion criteria were articles in English language focusing on the use of bone substitutes in trauma and orthopaedic surgery for the treatment of bone defects and included details on the structural, biological or biomechanical properties of the pure product. Furthermore, based on two clinical challenges, fracture non-union and impaction grafting we elaborated on the use of polytherapy for large bone defects as guided by the diamond concept.

RESULTS

All the products indicated in this manuscript possess osteoconductive activities but have different resorption times and biomechanical properties. Bone graft substitute materials are used for a wide range of clinical applications even when the level of clinical evidence is low. The size and location of the defect and the local biological and mechanical environment as well as the biomechanical characteristics of the material determine the type of device that can be implanted in a bone defect.

CONCLUSION

Proper assessment of the biological and mechanical environment and accurate patient selection are necessary to judge the extent of therapy the injury warrants. A sound understanding of various aspects of biomaterial properties and their relation and influence towards bone healing is of utmost importance. We suggest the application of polytherapy for the treatment of large bone defects and advocate the use of the diamond concept as a guideline.

Persistence of polypropylene mesh anisotropy after implantation: an experimental study

OBJECTIVE

To determine whether anisotropy persisted after incorporation into the host, using a standardised rabbit model for abdominal wall reconstruction.

DESIGN

Investigator-initiated prospective-controlled experimental study.

SETTING

Centre for Surgical Technologies, Medical Faculty KU-Leuven.

SAMPLE

Fifteen New Zealand White rabbits.

METHODS

In each rabbit, four full thickness primarily repaired abdominal wall defects were covered by a 4 × 5-cm Prolift+M implant (Johnson & Johnson, Norderstedt, Germany), either with the stiffest (n = 6 rabbits) or most elastic (n = 6) direction parallel to the body axis. Prolift+M contains 32 g/m² polypropylene, reinforced with polyglecaprone fibres. Harvesting was performed after 30, 60 and 120 days (n = 2 each time-point). The abdominal wall of three unoperated rabbits was used as negative control.

MAIN OUTCOME MEASURES

Contraction, compliance and maximal strain and stress determined by uniaxial tensiometry.

RESULTS

Anisotropy properties persist at lower, more physiological displacements, but not at higher displacements. The stiffness of a mesh-augmented repair in the lower strain range remains above that of native tissue. Eventual mesh contraction was limited to 4.3%.

CONCLUSIONS

Anisotropic properties of Prolift+M persist in vivo and shrinkage is minimal. Compliance of mesh-augmented repair remains less than that of native tissue. The functional consequences of this remain to be studied.

Time course of hypothalamic-pituitary deficiency in adults receiving cranial radiotherapy for primary extrasellar brain tumors

BACKGROUND

No longitudinal data on hypothalamic-pituitary (HP) function are available in patients who had received cranial radiation therapy (CRT) for primary extrasellar brain tumors (PBT).

PURPOSE

To investigate the effects of CRT on HP function in adults with PBT.

PATIENTS AND METHODS

Twenty-six adults irradiated for PBT and six CRT naive controls were studied. CRT was delivered with 6 MV X-ray by a linear accelerator (2 Gy fraction schedule). Gross Tumor Volume (GTV) excluded the HP region that was contoured on the planning CT. Median dose to the HP region was 41.8 Gy (IQR: 30.7-49.8).

RESULTS

All controls maintained normal HP function. Hypopituitarism developed in 38% of CRT patients (GH deficiency 29%, ACTH 22%, TSH 14%, gonadotropin 4%, no abnormal prolactin level or diabetes insipidus). All HP failures occurred within 32 months after CRT.

CONCLUSIONS

Adults undergoing CRT for PBT are at increased risk for HP dysfunction within 3 years from CRT. Endocrine surveillance is recommended also in adults patients exposed to CRT for primary brain tumors distant from HP region.

Mussel-mimetic tissue adhesive for fetal membrane repair: a standardized ex vivo evaluation using elastomeric membranes

OBJECTIVE

Iatrogenic preterm premature rupture of membranes (iPPROM), the main complication of invasive interventions in the prenatal period, seriously limits the benefit of diagnostic or surgical prenatal procedures. This study aimed to evaluate preventive plugging of punctured fetal membranes in an ex vivo situation using a new mussel-mimetic tissue adhesive (mussel glue) to inhibit leakage.

METHODS

A novel biomechanical test device that tests the closure of injured membranes under near-physiological conditions was used. Mussel glue, a poly(ethylene glycol)-based hydrogel, was used to seal membrane defects of up to 3 mm in mechanically well-defined elastomeric membranes with three different degrees of stiffness.

RESULTS

Elastomeric test membranes were successfully employed for testing mussel glue under well-defined conditions. Mussel glue plugs were distended by up to 94%, which translated to an improved sealing efficiency on elastomeric membranes with high stiffness. For the stiffest membrane tested, a critical burst pressure of 48 mbar (36 mmHg) was accomplished in this ex vivo setting.

CONCLUSIONS

Mussel glue appears to efficiently seal membrane defects under well-standardized ex vivo conditions. As repaired membranes resist pressures measured in amniotic cavities, mussel glue might represent a novel sealing method for iatrogenic membrane defects.

Polytherapy in Bone Regeneration: Clinical Applications and Preliminary Considerations

Polytherapy, namely the simultaneous application of three fundamental elements necessary for bone regeneration (growth factors, osteogenic cells and osteocnductive scaffolds) seems to lead to a very high success rate in the treatment of complex non-union (NU) cases and critical bone defects. NU are reported in 5–10% of long bone fractures. The use of autologous bone grafts has been long-considered the gold standard for the treatment of these cases. However the harvesting procedure from the iliac crest increases surgery time and presents some donor site complications which may be elevated. In recent years, surgeons have some alternatives to autologous grafting such as: application of organic or synthetic bone substitute, application of mesenchymal stromal cells (MSC) or growth factors (GF). In the literature there are many studies available about their application in monotherapy, but unfortunately the healing rate doesn't exceed 90%. Polytherapy seems to be a logical option to improve the healing rate, nevertheless, there are not still extensive studies that validate this strategy and moreover, some questions are not resolved.

Salvage therapy with temozolomide in patients with aggressive or metastatic pituitary adenomas: experience in six cases

OBJECTIVE

The prognosis of either pituitary carcinoma or aggressive pituitary adenoma resistant to standard therapies is poor. We assessed the efficacy of treatment with temozolomide, an oral second-generation alkylating agent, in a consecutive series of six patients with aggressive pituitary adenomas.

DESIGN

This was a 1-year prospective study of temozolomide therapy in six consecutive patients with pituitary carcinoma (one case) or atypical pituitary adenoma (five cases) resistant to standard therapies. There were three males and three females. Age at enrollment ranged between 52 and 64 years. Temozolomide was given orally at a dose of 150-200 mg/m(2) per day for 5 days every 4 weeks for a maximum of 12 cycles.

METHODS

Response assessment was based on measurable change in tumor size, as assessed on magnetic resonance imaging, and hormone levels. Response was defined as reduction of at least 50% of tumor size and hormone levels.

RESULTS

Four patients completed the 12 cycles of temozolomide treatment, as planned. Two patients stopped the drug after 3 and 6 months respectively because of the progression of disease. Two patients responded to temozolomide, while the remaining two patients had stable disease. Immunohistochemistry for O(6)-methylguanine-DNA methyltransferase (MGMT) in tumor sample showed a partial association with treatment response.

CONCLUSIONS

Temozolomide treatment has a wide range of efficacy in patients with pituitary carcinoma or locally aggressive pituitary adenoma. Positive staining for MGMT seems likely to predict a lower chance of response.

Combined versus sequential diuretic treatment of ascites in non-azotaemic patients with cirrhosis: results of an open randomised clinical trial

OBJECTIVE

The aim of the study was to compare sequential versus combined diuretic therapy in patients with cirrhosis, moderate ascites and without renal failure.

DESIGN

One hundred patients were randomly assigned to the two diuretic treatments. The sequential treatment provided potassium canrenoate at the initial dose of 200 mg/day, then increased to 400 mg/day. Non-responders were treated with 400 mg/day of potassium canrenoate and furosemide at an initial dose of 50 mg/day, then increased to 150 mg/day. The combined treatment provided the initial dose of 200 mg/day of potassium canrenoate and 50 mg/day of furosemide, then increased to 400 mg/day and 150 mg/day, respectively.

RESULTS

Most patients who received sequential treatment responded to potassium canrenoate alone (19% to 200 mg/day and 52.63% to 400 mg/day, respectively). Most patients who received the combined treatment responded to the first two steps (40% to the first step and 50% to the second, ie, 400 mg/day of potassium canrenoate plus 100 mg/day of furosemide). Adverse effects (38% vs 20%, p<0.05), in particular, hyperkalaemia (18% vs 4%, p<0.05), were more frequent in patients who received sequential therapy. As a consequence, the per cent of patients who resolved ascites without changing the effective diuretic step was higher in those who received the combined treatment (56% vs 76%, p<0.05).

CONCLUSIONS

The combined diuretic treatment is preferable to the sequential one in the treatment of moderate ascites in patients with cirrhosis and without renal failure. NCT00741663. This work is an open randomised clinical trial.

Development and validation of a three-dimensional finite element model of the face

A detailed three-dimensional finite element model of the face is presented in this paper. Bones, muscles, skin, fat, and superficial muscoloaponeurotic system were reconstructed from magnetic resonance images and modeled according to anatomical, plastic, and reconstructive surgery literature. The finite element mesh, composed of hexahedron elements, was generated through a semi-automatic procedure with an effective compromise between the detailed representation of anatomical parts and the limitation of the computational time. Nonlinear constitutive equations are implemented in the finite element model. The corresponding model parameters were selected according to previous work with mechanical measurements on soft facial tissue, or based on reasonable assumptions. Model assumptions concerning tissue geometry, interactions, mechanical properties, and the boundary conditions were validated through comparison with experiments. The calculated response of facial tissues to gravity loads, to the application of a pressure inside the oral cavity and to the application of an imposed displacement was shown to be in good agreement with the data from corresponding magnetic resonance images and holographic measurements. As a first application, gravimetric soft tissue descent was calculated from the long time action of gravity on the face in the erect position, with tissue aging leading to a loss of stiffness. Aging predictions are compared with the observations from an "aging database" with frontal photos of volunteers at different age ranges (i.e., 20-40 years and 50-70 years).

A randomized phase II trial of two different four-drug combinations in advanced pancreatic adenocarcinoma: Cisplatin, capecitabine, gemcitabine plus either epirubicin or docetaxel

4614

Background: The combination of cisplatin (P), epirubicin (E), 5-fluorouracil (F) and gemcitabine (G) (PEFG regimen) yielded a progression-free survival at 6 months from treatment start (PFS6) of about 50% and a 1-year overall survival (OS) around 40% in patients with advanced pancreatic adenocarcinoma (PA). The current trial was aimed to assess whether the replacement of E with docetaxel (D) may improve PFS6. Methods: Chemo-naive patients with stage III or metastatic PA, age 18–75y, Karnofsky performance status (PS) >50 received P (30 mg/m2 day 1), G (800 mg/m2 day 1) and capecitabine (1250 mg/m2/day days 1 to 14) and were randomized to receive either D at 25–30 mg/m2 day 1 (arm A: PDXG regimen) or E at 30 mg/m2 day 1 (arm B: PEXG regimen). Cycles were repeated every 14 days for a maximum of 6 months. Tumor was assessed by CT scan every 8 weeks. The Fleming design was used to calculate the sample size on the probability of being PFS6 (primary endpoint). Assuming P0=40% and P1=60%, α .05 and β.10, the study was to enroll 52 patients per arm. The regimen had to be considered of interest with > 26 patients being PFS6. Results: Between July 2005 and September 2008, 105 patients were enrolled at a single institution, stratified by stage and randomized (53 arm A). Patients’ characteristics were (A/B): median age 61/59, PS > 70 92/88%, metastatic disease 66/65%; CA19.9 > upper limit of laboratory normal (ULN) 87/90%, median CA19.9 820/755 UI/mL. To date, 46 patients per arm are assessable for the primary endpoint: PFS6 was 58/54%. One- year OS was 41% in both arms. A partial response was observed in 61/37% of patients. Among assessable patients with basal CA19.9 value > ULN (37 per arm), a major biochemical response (reduction >89%) was observed in 46/35% and a minor biochemical response (reduction between 50 and 89%) in 43/35% of patients. Main per cycle G3–4 toxicity was: neutropenia 4/13%, thrombocytopenia 3/2%, anemia 4/3%, fatigue 6/4%. Conclusions: PEXG yielded similar results when compared to prior series treated by PEFG, suggesting that capecitabine may replace F. The inclusion of D instead of E seems to be promising. The present trial confirms the relevant impact on outcome of advanced PA of four-drug regimens.

No significant financial relationships to disclose.

Outcome of upfront combination chemotherapy followed by chemoradiation for locally advanced pancreatic adenocarcinoma

PURPOSE

The role and timing of chemotherapy and radiation for treating stage III pancreatic adenocarcinoma remains controversial.

METHODS

Treatment-naive patients with stage III non-resectable pancreatic adenocarcinoma were treated with PEFG/PEXG (cisplatin, epirubicin, 5-fluorouracil (F)/capecitabine (X), gemcitabine) or PDXG (docetaxel substituting epirubicin) regimen for 6 months followed by radiotherapy (50-60 Gy) with concurrent F or X or G.

RESULTS

Ninety-one patients were registered between April 1997 and December 2007. Forty-three patients (47%) had a partial remission and 38 (42%) had a stable disease. Thirteen patients (14%) were radically resected yielding one pathologic complete remission. Median survival (OS) was 16.2 months. Median progression-free survival was 9.9 months. Pattern of failure consisted of isolated local failure (N = 26, 35%); both local and systemic failure (N = 14, 19%); isolated systemic failure (N = 35, 47%).

CONCLUSION

Combination chemotherapy with four-drug regimens followed by chemoradiation was a feasible strategy showing relevant results in stage III pancreatic adenocarcinoma.

Long-term follow-up of patients with hyperthyroidism due to Graves' disease treated with methimazole. Comparison of usual treatment schedule with drug discontinuation vs continuous treatment with low methimazole doses: a retrospective study

Antithyroid drugs may be proposed as the firstline therapy for hyperthyroidism due to Graves' disease since some patients undergo prolonged remission after drug withdrawal. On the other hand, some studies, though controversial, indicated that methimazole (MMI) has some immunomodulating activity. We retrospectively analyzed 384 consecutive patients newly diagnosed with Graves' disease in the years 1990-2002 to ascertain whether long-term therapy with low doses of MMI may prevent relapse of thyrotoxicosis. Two hundred and forty-nine patients were included in our study. The date of reduction of MMI dose to 5 mg/day was considered time 0 for survival analysis. In 121 MMI was discontinued in less than 15 months after time 0 (group D), while in the remaining 128 a daily MMI 2.5-5 mg dose was maintained (group M). One hundred and thirty-five patients were excluded for inadequate response to MMI, relapse of thyrotoxicosis that could be related to an improper withdrawal or reduction of MMI, inadequate or too short followup, iodide contamination, steroid or interferon therapy, pregnancy or post-partum. D and M groups did not differ for clinical and hormonal parameters except age, which was lower in D (p=0.019). Age > vs < 35 yr was relevant in survival analysis; therefore patients were divided in 2 groups according to this age cut-off. In younger patients relapse of thyrotoxicosis occurred in 15 patients of group D 2.4-39.6 months (median 19.0) after time 0, and 8 M after 5.9-40.0 (21.3) months, while 14 D and 5 M maintained euthyroidism until the end of the observation after 31.8-95.3 (56.6) months and 30.4-62.1 (46.5) months, respectively. Survival analysis indicated that the risk of relapse was similar in group D and M. In older patients relapse of thyrotoxicosis occurred in 40 patients of group D after 8.2-65.8 (25.4) months and 29 M after 5.8-62.5 (22.4) months, while 52 D and 86 M maintained euthyroidism until the end of the observation, 20.1-168.0 (46.7) months and 24.1-117.4 (53.4) months respectively. Survival analysis indicated that the risk of relapse was increased in group D. Therefore long-term treatment with low doses of MMI seems to prevent relapse in Graves' disease in patients above 35 yr of age. This should be confirmed in a prospective study.

Simulation of the aging face

A three-dimensional finite element program is described which attempts to simulate the nonlinear mechanical behavior of an aging human face with specific reference to progressive gravimetric soft tissue descent. A cross section of the facial structure is considered to consist of a multilayered composite of tissues with differing mechanical behavior. Relatively short time (elastic-viscoplastic) behavior is governed by equations previously developed which are consistent with mechanical tests. The long time response is controlled by the aging elastic components of the tissues. An aging function is introduced which, in a simplified manner, models the observed loss of stiffness of these aging elastic components due to the history of straining as well as other physiological and environmental influences. Calculations have been performed for 30 years of exposure to gravitational forces. The deformations and stress distributions in the layers of the soft tissues are described. Overall, the feasibility of using constitutive relations which reflect the highly nonlinear elastic-viscoplastic behavior of facial soft tissues in finite element based three-dimensional mechanical analyses of the human face is demonstrated. Further developments of the program are discussed in relation to possible clinical applications. Although the proposed aging function produces physically reasonable long-term response, experimental data are not yet available for more quantitative validation.

Anaplastic astrocytoma in adults

Anaplastic astrocytoma is an uncommon disease in the adult population. Prognosis is influenced by age, symptom duration, mental status and Karnofsky performance status. A truly complete resection, which is a recognized independent prognostic factor, is not possible and recurrence in the surgical cavity is common. Based on randomized data available, chemotherapy has consistently failed to improve the outcome of patients with anaplastic astrocytoma, while a meta-analysis showed a small, but significant improvement in survival favouring the use of chemotherapy. Outside a clinical trial, postoperative radiotherapy (30 x 2 Gy) remains the standard adjuvant therapy for most patients. For elderly patients, the application of treatment is usually based on performance status and neurological function. In recurrent disease, chemotherapy with temozolomide has been proven to be active and well-tolerated in phase II trials, but no comparative phase III trials of other cytotoxic drugs have been conducted.

A randomized phase II trial of PEXG (cisplatin, epirubicin, capecitabine, gemcitabine) or PDXG (docetaxel) regimen in advanced pancreatic adenocarcinoma

4628

Background: Four-drug regimen significantly improved the outcome of patients with advanced pancreatic adenocarcinoma (PA) with respect to standard gemcitabine in a phase III trial (Reni Lancet Oncol 2005). The current study was an attempt to further improve progression-free survival (PFS) by replacing epirubicin with docetaxel. Methods: Patients with stage III or metastatic PA, age 18–75y, Karnofsky performance status (PS) >50 were randomized to receive either D (arm A: 25 mg/m2 day 1 and 14) or E (arm B: 30 mg/m2 day 1 and 14) while P (30 mg/m2 day 1 and 14), G (800 mg/m2 day 1 and 14) and X (1250 mg/m2/day days 1 to 28) remained unmodified in the two arms. Cycles were repeated every 28 days. The primary endpoint of the study was PFS. The sample size was calculated on the probability of being PF at 6 months (PFS6) from treatment start. Assuming P0=25% and P1=45%, with a .05 and b.20, the study was to enroll 32 patients per arm. Results: Between July 2005 and January 2007, 64 patients were enrolled at a single institution, stratified by stage and randomized (32 per arm). Main patient characteristics were balanced (A/B): median age 61/58, PS > 70 93/84%, metastatic disease 69/69%. Treatment is ongoing in 6/7 patients; 16/15 patients concluded at least 6 cycles of chemotherapy while 9/10 interrupted treatment due to progressive disease (PD) and 1/0 due to consent withdrawal. To date, 51 patients are assessable for response and PFS6: 16 of 26 (62%) arm A patients and 12 of 25 (48%) arm B achieved a partial response. PFS6 was 54%/44%. Final results of toxicity, activity, PFS6 and survival will be available at time of meeting. Conclusion: PEXG regimen yielded similar results when compared to historical series treated by PEFG regimen, suggesting that the use of capecitabine instead of 5- fluorouracil did not compromise the outcome. The inclusion of D instead of E seems to be promising. The present trial further confirms the relevant impact on outcome of advanced PA of four-drug regimens.

No significant financial relationships to disclose.