Biological reconstruction for children with osteosarcoma around the knee.

INTRODUCTION: Limb salvage in children with primary malignant bone tumours around the knee is challenging, with considerations such as shortening, bone and joint remodeling and high functional demands of active children. The ultimate aim for reconstruction is restoring a stable, painless and mobile joint. With improved survival rates from chemotherapy, reconstructive techniques should ideally last the child's lifespan. We adopted a biological approach by preserving the patients' native joint, with bony defects bridged by fibula grafts supplemented by autoclaved bone grafts infused with bone marrow. We conducted this retrospective review to determine if we were able to meet our objectives of reconstruction. MATERIALS AND METHODS: A retrospective review of children with osteogenic sarcoma involving the distal femur or proximal tibia treated at our institution was done. Patients aged 13 years and below at the time of surgery who had undergone a limb salvage procedure that preserved the knee joint were included. RESULTS: Nine patients were identified, 3 males and 6 females. The average age was 10.0 years (range, 7 to 13 years) at the time of surgery. Seven had tumours involving the distal femur while 2 had tumours involving the proximal tibia. There were no cases of local recurrence. Four of the 9 patients died from metastatic disease, the 5 surviving patients have no evidence of disease, and the average follow-up for survivors was 13.2 years. The average active range of motion for the knee joint was 96° (range, 50° to 130°). The average Musculoskeletal Tumour Society (MSTS) score was 26.3 (range, 23 to 30). CONCLUSION: We have observed this technique of limb salvage offers satisfactory limb function with long-term follow-up.

The reconstruction of large bone defects in the upper limb.

Large bone defects in the upper limb pose many challenges in reconstructive surgery. Conventional and innovative methods have been described, employing the use of microsurgical and non-microsurgical techniques to overcome both bony and soft tissue defects. This article reviews the success and pitfalls of different techniques of reconstruction of large bone defects in the upper limb, including microsurgical transfer of the free vascularised fibula graft as a diaphyseal bone replacement and as a hemivascularised joint transplant, and non-microsurgical options using conventional bone grafting, the induced membrane technique and the role of callotatic distraction-lengthening procedures.

Fitting very short finger stumps with silicone prosthesis: a nonsurgical method.

BACKGROUND AND AIM: The fitting of short finger stumps with silicone prosthesis is a challenge because of the suboptimal finger-prosthesis contact due to length and distal tapering of digital stumps. The purpose of this report was to describe and evaluate the Micropore(™)-polyvinyl chloride tube technique for fitting short finger stumps. TECHNIQUE: For a total of 10 patients, short finger stumps were fitted using the technique. A short length of polyvinyl chloride tube, trimmed and contoured to fit, was secured on the distal stump tip with Micropore tape. The prosthesis was worn over the polyvinyl chloride tube extension. Three different fitting methods were evaluated: fitting with and without the Micropore-polyvinyl chloride tube technique, and with the use of skin adhesive on the stump. DISCUSSION: All patients achieved a very secure prosthetic fit with the Micropore-polyvinyl chloride tube technique. No incidences of prosthesis slippage were reported at the longest follow-up of 30 months. The Micropore-polyvinyl chloride tube technique is an effective method for fitting short finger stumps.

Runx2, p53, and pRB status as diagnostic parameters for deregulation of osteoblast growth and differentiation in a new pre-chemotherapeutic osteosarcoma cell line (OS1).

Osteosarcomas are the most prevalent primary bone tumors found in pediatric patients. To understand their molecular etiology, cell culture models are used to define disease mechanisms under controlled conditions. Many osteosarcoma cell lines (e.g., SAOS-2, U2OS, MG63) are derived from Caucasian patients. However, patients exhibit individual and ethnic differences in their responsiveness to irradiation and chemotherapy. This motivated the establishment of osteosarcoma cell lines (OS1, OS2, OS3) from three ethnically Chinese patients. OS1 cells, derived from a pre-chemotherapeutic tumor in the femur of a 6-year-old female, were examined for molecular markers characteristic for osteoblasts, stem cells, and cell cycle control by immunohistochemistry, reverse transcriptase-PCR, Western blotting and flow cytometry. OS1 have aberrant G-banded karyotypes, possibly reflecting chromosomal abnormalities related to p53 deficiency. OS1 had ossification profiles similar to human fetal osteoblasts rather than SAOS-2 which ossifies ab initio (P < 0.05). Absence of p53 correlates with increased Runx2 expression, while the slow proliferation of OS1 cells is perhaps attenuated by pRB retention. OS1 express mesenchymal stem cell markers (CD44, CD105) and differ in relative expression of CD29, CD63, and CD71 to SAOS-2. (P < 0.05). Cell cycle synchronization with nocodazole did not affect Runx2 and CDK1 levels but decreased cyclin-E and increased cyclin-A (P < 0.05). Xenotransplantion of OS1 in SCID mice yields spontaneous tumors that were larger and grew faster than SAOS-2 transplants. Hence, OS1 is a new osteosarcoma cell culture model derived from a pre-chemotherapeutic ethnic Chinese patient, for mechanistic studies and development of therapeutic strategies to counteract metastasis and deregulation of mesenchymal development.

Elevated expression of Runx2 as a key parameter in the etiology of osteosarcoma.

To understand the molecular etiology of osteosarcoma, we isolated and characterized a human osteosarcoma cell line (OS1). OS1 cells have high osteogenic potential in differentiation induction media. Molecular analysis reveals OS1 cells express the pocket protein pRB and the runt-related transcription factor Runx2. Strikingly, Runx2 is expressed at higher levels in OS1 cells than in human fetal osteoblasts. Both pRB and Runx2 have growth suppressive potential in osteoblasts and are key factors controlling competency for osteoblast differentiation. The high levels of Runx2 clearly suggest osteosarcomas may form from committed osteoblasts that have bypassed growth restrictions normally imposed by Runx2. Interestingly, OS1 cells do not exhibit p53 expression and thus lack a functional p53/p21 DNA damage response pathway as has been observed for other osteosarcoma cell types. Absence of this pathway predicts genomic instability and/or vulnerability to secondary mutations that may counteract the anti-proliferative activity of Runx2 that is normally observed in osteoblasts. We conclude OS1 cells provide a valuable cell culture model to examine molecular events that are responsible for the pathologic conversion of phenotypically normal osteoblast precursors into osteosarcoma cells.

Innervation of the Face Studied Using Modifications to Sihler's Technique in a Primate Model.

BACKGROUND: There has been no reliable technique with which to display the innervation within whole-tissue specimens of the face. Such a technique preserves the architecture of the facial muscles and provides new data on intramuscular and sensory neural networks. Sihler's technique preferentially stains myelinated nerves within whole tissue, which is rendered transparent. On transillumination, entire neural networks can be studied in situ without the need for dissection and histologic examination. The purpose of this study was to apply Sihler's technique to study innervation patterns of the face, define end points, and improve specimen transillumination. METHODS: Eight macaque fascicularis monkeys were studied. The mimetic muscles of the face with intact facial nerve and sensory nerves were harvested as whole tissue composites. Sihler's technique was modified with formalin fixation before dissection to minimize autolysis of the myelin sheath. Prolonged immersion in glycerin improved tissue transparency. A replica of the skull was made with silicone and a light source embedded to restore three-dimensional configuration and provide transillumination. RESULTS: The facial nerve and sensory nerves were clearly seen up to their terminations in the transparent muscle and soft tissue. Observations were made with regard to the extramuscular and intramuscular innervation patterns of the facial nerve and sensory nerve patterns. CONCLUSIONS: Sihler's technique is a simple and reliable method with which to study the innervation of the face. This process may be applied to the human face to provide a much-needed roadmap to surgery, and the primate model may be developed for the study of facial reinnervation, facial reanimation, and dynamic facial transplantation.

Assessment of colour differences in silicone hand and digit prostheses: perceptible and acceptable thresholds for fair and dark skin shades.

This study addresses the dilemma of initial clinical and social acceptance of a newly fabricated silicone prosthesis in relation to its colour match to the natural skin. This was achieved by derivation of specific colour difference thresholds defining perceptible and acceptable levels of colour sensitivity. Two separate sets of 10 fair and dark shade digit prosthesis samples were each fabricated with a stepped increase in colour difference (deltaE) against the baseline hand prosthesis. Ninety individuals with normal colour vision scores were selected as colour assessors. The colour difference of each prosthesis in the two series was evaluated visually against the baseline by the assessors, using defined scores. The thresholds for perceptible and acceptable colour difference determined in this study were deltaE= 0.8 and deltaE= 1.8 for the fair series and deltaE = 1.3 and deltaE = 2.6 for the dark series, respectively. The acceptable threshold values differed from the perceptible threshold values by deltaE= 1.0 for the fair-shade samples and deltaE= 1.3 for the dark-shade samples. This study demonstrated that subjective visual assessment is positively correlated with deltaE values computed from colorimetric measurements for both fair and dark-shade silicone samples (p<0.001). This results shows that human subjects with normal colour vision are capable of accurately assessing colour differences. These observations emphasize the importance of subjective feedback on colour by the patient, provided the latter has perfect colour-tested vision. The study also showed that human subjects were less sensitive to perceived colour differences in darker-shade than fairer-shade samples (p < 0.001). This finding seems relevant in a clinical setting involving a multi-ethnic patient population.

Reverse anterior tibial artery flap for reconstruction of foot donor site.

The foot offers numerous useful options for hand reconstruction. Hallux transfer, dorsalis pedis flap, second toe transfers, and toe joint transfers offer good functional results in reconstructed hands. However, when the donor site is repaired with skin grafts, delayed wound healing, scarring, and contractures often result. Poor cosmesis of the donor site and altered gait are the main drawbacks of the procedures. The authors propose a new concept of primary reconstruction of the donor foot using a reverse-flow anterior tibial flap from the same leg. Two flaps are raised from the same anterior tibial vessel system in continuity as a distal free flap for hand reconstruction and as a proximal reverse-flow pedicled flap to resurface the donor defect. This technique allows good flap reconstruction of the foot donor site, reducing morbidity and limiting the operation to the same limb. The authors report their experience of 33 cases. There were no failures. Primary wound healing was achieved in the foot donor site, with acceptable cosmesis and satisfactory function.