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Large allograft bones are commonly used in limb salvage procedures for the reconstruction of bone defects after resection of a bone tumor. A V-shaped osteotomy may perform better than the traditional transverse osteotomy as it increases the stability of the docking site and increases the contact area between an allograft and the host cortex. The aim of this study is to investigate the biomechanical properties of a V-shaped docking site of different angles.

orcine femurs with 45°, 60° or 90° V-shaped osteotomy were first tested with 1000 N compression, followed by 2 and 5 Nm torque. The torsional stiffness of the 45° specimen group at 5 Nm torque was significantly higher (P<0.05) than the 90° group. Therefore, our results show that 45° V-shaped osteotomy is found to be the most stable docking angle.

Infections following limb-saving surgeries still happen frequently and are refractory to treatment, even though the treatment of massive bone defects caused by bone resection of bone tumors has improved gradually. Once infections become intractable, they generally result in amputations in spite of all kinds of treatment. We report the case of a patient who developed an intractable infection after limb-saving surgery utilizing a massive frozen autograft and a tumor prosthesis, but whose limb was finally successfully salvaged by multiple surgical interventions. We conclude that continued perseverance in treatment after infections may enable preservation of the limb and restoration of good function.

Patients with lower extremity soft tissue sarcoma (STS) need to recover their walking ability while coping with lower-limb muscle loss due to tumor removal. However, the lack of information on walking after tumor removal hinders the development of gait rehabilitation strategies for such patients. The present study explored how patients walked after STS resection from the viewpoint of muscle forces. The effect of muscle removal and muscle strength asymmetry on estimated muscle forces was also investigated by iterating gait simulations for each patient using three different musculoskeletal models. These models differed based on whether or not the resected muscles were reflected in the model and whether or not residual muscle strength was scaled according to muscle strength measurements. Muscle forces during walking were estimated in six patients after thigh STS removal. Our results suggested that patients could walk using not only residual muscles that function similar to the resected muscles but also those that function differently (e.g., ankle plantarflexors). Gait simulations of patients with considerable muscle loss and those without a rectus femoris muscle were relatively sensitive to muscle removal.

Endoprosthetic reconstruction using a custom-made metallic megaendoprosthesis is one of the common modalities for the limb salvage operation. The new promising advance of material science, design and fabrication of the endoprosthesis enable an immediate rehabilitation program and provide a durable and functional limb. Thus a successful limb reconstruction is possible in the well-selected patients. In addition to the endoprosthesis-related increased stress, a limited soft tissue support and constraint after limb salvage procedure usually results in an increased incidence of complications, especially in the long term survivors. Some patients may even need revision of the endoprosthesis and, at times, amputation.

The complications after oncological endoprosthectic reconstructions usually occur more frequent than the conventional primary total joint arthroplasty. Considering the characteristics of the surgical procedure and the high demands on the implants, such a relatively high frequency of complications is not unexpected. The common complications include wound necrosis, aseptic loosening, fatigue fracture, local osteolysis, joint contracture, dislodgement/dislocation, nerve or vascular injury, rotational deformity, leg length discrepancy, infection, periprosthectic fracture, etc. Some complications are encountered with other modality of limb salvage procedure, whereas the other endoprosthesis-related complications are endoprosthetic-unique and not uncommon. The major causes of such a relatively high endoprosthesis-related complications include (1) extensive excision of soft tissue, leading to change of biomechanical ergonomics, little soft tissue constraints or support for a long replacement segments, and decreased local defense to infection, (2) increased stress on the implants due to higher activity level in the youthful active individuals, relatively narrower medullary canals with less cancellous bone for fixation, (3) special needs for the stability resulting an increased mechanical constraints placed directly within the endoprosthesis, thus raising the local stress transferred to the prosthesis, and to the prosthesis-bone interface, (4) poor immunological, hematological, or nutritional status resulting from chronic oncologic diseases or chemotherapy. It in turn accelerates the wear processes of the components, induces the wear particulate disease and local osteolysis, as well as to cause the aseptic loosening eventually. Early detection and early correction of minor complications has an important role of preventing the major complications, thus reduces the necessity of reoperation, and at times, amputation. We will review these complications in this article.

Major lower limb amputation is the most dreadful complication of diabetic foot. A review on Hong Kong Chinese diabetics with ulcerated feet has identified ulcer depth, peripheral vascular insufficiency, old age and hypoalbuminemia to be factors associated with major amputation. An infected ulcer, neuropathy, anaemia and low lymphocyte count are frequently observed in this group of amputees. Amputation has a seasonal variation and is more commonly performed in summer. Establishing a dedicated clinic for this group of patients can lead to a dramatic decrease in amputation. Input from different disciplines is of vital importance to its success.