Impaction bone grafting for segmental acetabular defects: a biomechanical study

Introduction Implant loosening is the most common indication for revision after total hip arthroplasty and is associated with progressive bone destruction. Contained defects can be treated with impaction bone grafting (IBG). Segmental defects are successfully restored with metal augmentation. Considering the increasing number of hip arthroplasty cases in young patients, it would appear sensible to reconstruct the bone stock for future revisions by biological bone defect reduction. The data on the treatment of segmental defects with IBG without additional stabilization are lacking. Materials and methods Paprosky type IIB defects were milled into 15 porcine hemipelves with segmental defect angles of 40°, 80° and 120°. Contained defects without segmental defects (Paprosky type I) and acetabula without defects served as controls. After IBG, a cemented polyethylene cup (PE) was implanted in each case. Cup migration, rotational stiffness and maximum rupture torque were determined under physiological loading conditions after 2500 cycles. Results Compared with the control without defects, IBG cups showed an asymptotic migration of 0.26 mm ± 0.11 mm on average. This seating was not dependent on the size of the defect. The maximum rupture moment was also not dependent on the defect size for cups after IBG. In contrast, the torsional stiffness of cups with an 120° segmental defect angle was significantly lower than in the control group without defects. All other defects did not differ in torsional stiffness from the control without defects. Conclusions IBG did not show inferior biomechanical properties in segmental type IIB defect angles up to 80°, compared to cups without defects.

Immediate Mandibular Reconstruction Using a Cellular Bone Allograft Following Tumor Resection in a Pediatric Patient

Reconstruction of large segmental mandibular defects presents a challenge for oral and maxillofacial surgeons, particularly in the skeletally immature pediatric patient. Autogenous bone graft is historically preferred; however, harvest of autograft requires a second surgical site, risking donor-site complications as well as the potential for long-term complications in the growing child. Here, we present the first known report of a pediatric patient who underwent immediate mandibular reconstruction of a 6.5-cm long segmental defect using a cellular bone allograft (VF-CBA) combined with custom-fabricated guides and plates following tumor resection. The use of VF-CBA, along with the custom guides and plates, eliminated the need for autograft harvest in a child, enabled an entirely intraoral approach, avoiding the creation of a cutaneous scar, and reduced the total operative time, resulting in a fast recovery and improved patient satisfaction. By 7 months postoperative, the patient’s mandible was fully healed with solid osseous consolidation. These results support VF-CBA combined with custom intraoral guides and plates as an effective treatment option for reconstruction of large segmental mandibular defects in a pediatric patient.

Establishment of a reliable model to study the failure of fracture healing in aged mice

The failure of fracture healing represents a substantial clinical problem. Moreover, aged patients demonstrate an elevated risk for failed bone healing. However, murine models to study the failure of fracture healing are established only in young adult animals. Therefore, the aim of this study was to develop a reliable model to study failed fracture healing in aged mice. After creation of a 1.8 mm segmental defect and periosteal resection, femora of aged mice (18-20 months) and young adult control mice (3-4 months) were stabilized by pin-clip fixation. Segmental defects were analyzed by means of biomechanics, X-ray and micro-computed tomography (µCT), as well as histomorphometric, immunohistochemical and Western blot analysis. After 10 weeks all animals showed a complete lack of osseous bridging, resulting in fracture healing failure. Segmental defects in aged mice revealed a reduced bone formation and vascularization when compared to young adult mice. This was associated with a decreased expression of bone formation markers. In addition, we detected a reduced number of tartrate-resistance acid phosphatase (TRAP)-positive osteoclasts and an elevated osteoprotegerin (OPG)/receptor activator of NF-ĸB ligand (RANKL)-ratio in aged animals, indicating a reduced osteoclast activity. Moreover, aged animals showed also an enhanced inflammatory response, characterized by an increased infiltration of macrophages within the callus tissue. Taken together, we herein report for the first time a reliable model to study fracture healing failure in aged mice. In the future, the use of this model enables to study novel therapeutic strategies and molecular mechanics of failed fracture healing during aging.

Management of bone loss

Bone defects in the lower limb are the result of trauma, tumour resection, infection, or congenital defects. They can be classified by cause or extent. The management depends on the extent. Options for treatment include allowing the defect to heal, augmenting a partial defect with bone graft, or in the case of segmental defects either shortening the bone to allow direct healing or replacing the segmental defect by techniques of bone transport, the Masquelet technique of membrane induction of bone graft incorporation, massive allograft replacement, or using the variety of vascularized bone flaps available.

Successful utilization of triphasic silica containing ceramic coated hydroxyapatite (HASi) for the treatment of comminuted tibial fracture in a goat: a case report

A one year old female Sirohi crossbred goat was presented with a history of non weight bearing lameness on right hind limb. Radiography revealed comminuted fracture of tibial mid diaphysis. The comminuted fracture fragments and bone devoid of any soft tissue were surgically removed and the resultant segmental defect was reinstated with triphasic silica containing ceramic coated hydroxyapatite (HASi) after stabilising the fracture fragments with 2.7mm dynamic compression plate and screws. The animal recovered with normal limb ambulation after the eighth post-operative week.

Double-barrel Free Fibula for Segmental Defect of Ulna and Radius: Case Report

Introduction - Post traumatic complex defects of the forearm require multiple operations and prolonged rehabilitation. Segmental bony defects of the radius and ulna are occasionally seen as part of these complex wounds. There are a few options in bridging the skeletal defect. These include corticocancellous bone grafting, creation of a one bone forearm and vascularised fibula. Vascularised bone grafting is superior in an ischemic and fibrosed area as it enhances local blood supply. The fibula is usually used to bridge the defect in one bone i.e. the radius. Case presentation – A young male presented with an open comminuted fracture of radius and ulna following a crush injury to the left upper limb. The reconstruction was done in two stages – first a pedicled thoracoumbilical flap for soft tissue and in later stage a double barrel free fibula flap for segmental bone loss. Conclusion – The above approach offered the best chance of skeletal healing in a complex defect. The patient was able to gain reasonably good upper extremity function with the described technique.