The stability of the hip after the use of a proximal femoral endoprosthesis for oncological indications: analysis of variables relating to the patient and the surgical technique.

AIMS: Instability of the hip is the most common mode of failure after reconstruction with a proximal femoral arthroplasty (PFA) using an endoprosthesis after excision of a tumour. Small studies report improved stability with capsular repair of the hip and other techniques, but these have not been investigated in a large series of patients. The aim of this study was to evaluate variables associated with the patient and the operation that affect post-operative stability. We hypothesised an association between capsular repair and stability. PATIENTS AND METHODS: In a retrospective cohort study, we identified 527 adult patients who were treated with a PFA for tumours. Our data included demographics, the pathological diagnosis, the amount of resection of the abductor muscles, the techniques of reconstruction and the characteristics of the implant. We used regression analysis to compare patients with and without post-operative instability. RESULTS: A total of 20 patients out of 527 (4%) had instability which presented at a mean of 35 days (3 to 131) post-operatively. Capsular repair was not associated with a reduced rate of instability. Bivariate analysis showed that a posterolateral surgical approach (odds ratio (OR) 0.11, 95% confidence interval (CI) 0.02 to 0.86) and the type of implant (p = 0.046) had a significant association with reduced instability; age > 60 years predicted instability (OR 3.17, 95% CI 1.00 to 9.98). Multivariate analysis showed age > 60 years (OR 5.09, 95% CI 1.23 to 21.07), female gender (OR 1.73, 95% CI 1.04 to 2.89), a malignant primary bone tumour (OR 2.04, 95% CI 1.06 to 3.95), and benign condition (OR 5.56, 95% CI 1.35 to 22.90), but not metastatic disease or soft-tissue tumours, predicted instability, while a posterolateral approach (OR 0.09, 95% CI 0.01 to 0.53) was protective against instability. No instability occurred when a synthetic graft was used in 70 patients. CONCLUSION: Stability of the hip after PFA is influenced by variables associated with the patient, the pathology, the surgical technique and the implant. We did not find an association between capsular repair and improved stability. Extension of the tumour often dictates surgical technique; however, our results indicate that PFA using a posterolateral approach with a hemiarthroplasty and synthetic augment for soft-tissue repair confers the lowest risk of instability. Patients who are elderly, female, or with a primary benign or malignant bone tumour should be counselled about an increased risk of instability. Cite this article: Bone Joint J 2017;99-B:531-7.

Myogenic transcription factors regulate pro-metastatic miR-182.

Approximately 30% of patients with soft-tissue sarcoma die from pulmonary metastases. The mechanisms that drive sarcoma metastasis are not well understood. Recently, we identified miR-182 as a driver of sarcoma metastasis in a primary mouse model of soft-tissue sarcoma. We also observed elevated miR-182 in a subset of primary human sarcomas that metastasized to the lungs. Here, we show that myogenic differentiation factors regulate miR-182 levels to contribute to metastasis in mouse models. We find that MyoD directly binds the miR-182 promoter to increase miR-182 expression. Furthermore, mechanistic studies revealed that Pax7 can promote sarcoma metastasis in vivo through MyoD-dependent regulation of pro-metastatic miR-182. Taken together, these results suggest that sarcoma metastasis can be partially controlled through Pax7/MyoD-dependent activation of miR-182 and provide insight into the role that myogenic transcription factors have in sarcoma progression.

[Femur reconstruction using combined autologous fibula transfer and humeral allograft]. / Femurrekonstruktion mit kombiniertem autologem Fibulatransfer und Humerus-Allograft.

Wide resection far into the femoral metaphysis may be required to treat malignant bone tumors in the pediatric and adolescent patient population. Biological reconstruction using a free, vascularized fibular graft is a well-established surgical technique. A short remaining femoral medullary canal and a relatively small fibula diameter can make fixation of the vascularized bone transfer difficult. Stable fixation and short fusion times, however, can be achieved with the use of an additional humeral allograft and plate osteosynthesis.

Insulin-like growth factor-I is expressed by avian flexor tendon cells.

Cells in normal tendon are in a resting G0 state, performing maintenance functions. However, traumatic injury introduces growth factors such as platelet-derived growth factor and insulin-like growth factor from blood as well as activates endogenous growth factors. These factors stimulate migration and proliferation of tendon cells at the wound area. Tendon cells require growth-promoting factors to transit the cell cycle. To evaluate the contribution of endogenous growth factors in tendon, extracts of the epitenon and internal compartment of avian flexor tendon as well as medium of cultured cells from the epitenon (tendon surface cells) and internal tendon (tendon internal fibroblasts) were collected to assess their ability to stimulate DNA synthesis. Acid-ethanol extracts of tissues and medium were chromatographed on a P-30 molecular sieve column and assayed for mitogenic activity by quantitating [3H]thymidine incorporation into tendon cell DNA. The extract from the internal tendon compartment was more stimulatory for DNA synthesis than that from the epitenon, particularly when tested on tendon internal fibroblasts. However, conditioned medium fractions from surface epitenon cells stimulated DNA synthesis to a high degree on both tendon surface cells and tendon internal fibroblasts. Conditioned medium from tendon internal fibroblasts was also stimulatory. An anti-insulin-like growth factor-I antibody ablated most of the mitogenic activity present in both tissues and conditioned medium. The levels of acid-extractable insulin-like growth factor-I in tendon were determined by competitive radioimmunoassay as 1.48+/-0.05 ng/g tissue for the epitenon and 3.83+/-0.03 ng/g tissue for the internal compartment. Results of Western immunoblots of conditioned medium revealed insulin-like growth factor-I at the 7.5 kDa position. Cultured tendon surface cells and tendon internal fibroblasts as well as cells in intact flexor tendon expressed insulin-like growth factor-I mRNA detected by reverse transcriptase-polymerase chain reaction. In situ hybridization histochemistry positively identified insulin-like growth factor-I mRNA in tendons from 52-day-old chickens. Platelet-derived growth factor was not detected at the protein or message levels. Furthermore, tendon surface cells and tendon internal fibroblasts both expressed receptors for insulin-like growth factor-I detected by flow cytometry. These data suggest that tendon cells express insulin-like growth factor-I mRNA and synthesize insulin-like growth factor-I in both the epitenon and the internal compartment of tendon, which is present in an inactive form, most likely bound to insulin-like growth factor-binding proteins.

Fibronectin in the tendon-synovial complex: quantitation in vivo and in vitro by ELISA and relative mRNA levels by polymerase chain reaction and northern blot.

An enzyme-linked immunosorbent assay was used to quantitate fibronectin (Fn) levels in the outer synovia (epitenon) and internal fibrous portion (endotenon) of chicken flexor tendon and sheath. Primary cell cultures from these tissues and their secretions also were assayed for Fn levels. The polymerase chain reaction (PCR) was used to determine relative steady-state levels of Fn mRNA in primary cultures of synovial and internal fibroblasts from chicken tendon, and Northern blot analysis was performed to verify relative levels of the Fn message. The epitenon contained 3.8-fold more Fn than did the endotenon, and the sheath synovium contained 21-fold more Fn than did the internal fibrous portion of sheath. Cells cultured from the epitenon produced 9.3 and 13-fold more cell-associated and secreted Fn, respectively, than did cultured endotenon fibroblasts. Sheath synovial cells produced 17 and 3.2-fold more cell-associated and secreted Fn, respectively, than did sheath internal fibroblasts. Levels of Fn mRNA, as measured by PCR and Northern blot, were 1.6 and 1.8-fold greater, respectively, in tendon synovial cells compared with tendon internal fibroblasts. The biologic reason for increased Fn in tendon synovium is not known. We theorize that Fn may stabilize tendon synovium to shear stress and may play a role in the modulation of synovial rheology in the normal tendon. In the injured tendon, Fn may be involved in the organization of collagen deposition or may act through association with growth factors to aid healing.