Gastrointestinal stromal tumors (GISTs) are rare neoplasms of the gastrointestinal tract associated with high rates of malignant transformation. Most GISTs present asymptomatically. They are best identified by computed tomography (CT) scan and most stain positive for CD117 (C-Kit), CD34, and/or DOG-1. There have been many risk stratification classifications systems which are calculated based on tumor size, mitotic rate, location, and perforation. The approaches to treating GISTs are to resect primary low-risk tumors, resect high-risk primary or metastatic tumors with imatinib 400 mg daily for 12 months, or if the tumor is unresectable, neoadjuvant imatinib 400 mg daily followed by surgical resection is recommended. Sunitinib is required for KIT exon 9, 13, and 14 mutations, while ponatinib is used for exon 17 mutations and regorafenib for highly refractory tumors. High-risk tumors should be monitored for recurrence with serial abdominal CT scans. Radiofrequency ablation has shown to be effective when surgery is not suitable. Newer therapies of ipilimumab, nivolumab, and endoscopic ultrasound alcohol ablation have shown promising results. This report addresses the epidemiology, clinical presentation, diagnostic imaging, histologic diagnosis, classification and risk stratification, staging and grading, surgical treatment, adjuvant treatment, and metastasis of GISTs.

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* Revision hip arthroplasty is being performed with increasing frequency in the United States. One of the major challenges during these procedures is addressing associated femoral bone loss.* Varying degrees of proximal metaphyseal and diaphyseal bone loss may be treated with reconstruction techniques involving extensively porous-coated stems, distally based modular stems, and proximal femoral replacement. When diaphyseal bone loss extends beyond the isthmus of the femur with little support for a stem, reconstruction with replacement of the entire femur, hip, and knee (total femoral replacement) may be indicated.* Total femoral replacement is best indicated for older patients with massive loss of bone stock that makes them unsuitable for less-extensive reconstruction methods. The procedure is technically demanding and is associated with a high risk of complications, including major blood loss, deep infection, dislocation, and mechanical implant failure.* In appropriately selected patients, total femoral replacement can provide a successful salvage of an otherwise unreconstructible femur. (Previously, the only options available in such cases were nonoperative treatment, resection arthroplasty, or amputation.) In several case series, total femoral replacement has demonstrated good pain relief and improved function at intermediate to long-term follow-up.

The combination of a chronic quadriceps tendon rupture with lack of active knee extension and knee osteoarthritis is a rare and challenging problem. To our knowledge, this combined diagnosis and the treatment described in this case report have not been reported previously in the literature.

* U-type or H-type sacral fractures are a result of very high energy injuries that separate the lumbar spine and upper sacrum from the lower sacrum and pelvis. Advances in acute trauma care have resulted in an increase in the number of patients who survive this injury.* The choice of approach is dictated by several factors, including dorsal soft-tissue trauma, the need for neurological decompression, and the adequacy of sacral sagittal balance.* Complication rates following surgical treatment are high and primarily are related to the soft tissues.* This fracture pattern has a high association with polytrauma, major neurological injury (including cauda equina syndrome), and soft-tissue degloving injuries.* While nonoperative management may be appropriate for patients who are expected to be bedbound or non-weight-bearing for at least 3 months, the majority of these injuries are treated surgically with iliosacral screws and spinal constructs that anchor the pelvis to the lower lumbar spine.* Careful attention to damage-control principles, efficient surgical stabilization of the spondylopelvic injury and associated fractures, and early mobilization can lead to good functional outcomes following this potentially devastating injury.

» Compared with other proximal femoral fractures, subtrochanteric fractures are at a higher risk for nonunion because of the high deforming forces in this region, the associated increased risk of malreduction, and the risk of poor bone healing secondary to bisphosphonate use frequently associated with these fractures.» Further understanding of nonunion of subtrochanteric fractures is of increasing importance given the rise in incidence of subtrochanteric hip fractures.» Surgeons should be aware of risk factors for nonunion and techniques for prevention as well as surgical management and complications associated with surgical implantation devices.» Surgeons should also consider using adjuncts including bone-grafting and biologic agents.

➤ Modular fluted titanium stems have become the implant of choice for most femoral component revisions as they have a lower risk of subsidence, thigh pain, femoral fracture, and stress shielding compared with previously used extensively coated cobalt-chromium stems.➤ Modularity of the femoral component allows for optimal and independent fit and fill of the proximal and distal femoral segments, permitting immediate axial and rotational stability in shorter diaphyseal segments (<4 cm of scratch fit), thus reducing the risk of subsidence. Modularity also allows for independent adjustment of version of the proximal body relative to the distal stem, thus improving joint stability. The ability to make small adjustments in vertical and lateral offset further reduces the potential for instability and leg-length discrepancy, and the use of a titanium implant minimizes the risk of stress shielding compared with cobalt-chromium stems.➤ In several retrospective case series, excellent mid-term to long-term outcomes and low complication rates have been observed with the use of modular fluted titanium stems in femoral revisions.➤ The major disadvantages to the routine use of modular fluted titanium stems are the potential for taper junction failure (corrosion or fracture) and the increased cost of these stems compared with nonmodular stems.