Revascularization of femoral head ischemic necrosis with vascularized bone graft: a CT scan experimental study

The Clinical Application of Porous Tantalum and Its New Development for Bone Tissue Engineering

Porous tantalum (Ta) is a promising biomaterial and has been applied in orthopedics and dentistry for nearly two decades. The high porosity and interconnected pore structure of porous Ta promise fine bone ingrowth and new bone formation within the inner space, which further guarantee rapid osteointegration and bone-implant stability in the long term. Porous Ta has high wettability and surface energy that can facilitate adherence, proliferation and mineralization of osteoblasts. Meanwhile, the low elastic modulus and high friction coefficient of porous Ta allow it to effectively avoid the stress shield effect, minimize marginal bone loss and ensure primary stability. Accordingly, the satisfactory clinical application of porous Ta-based implants or prostheses is mainly derived from its excellent biological and mechanical properties. With the advent of additive manufacturing, personalized porous Ta-based implants or prostheses have shown their clinical value in the treatment of individual patients who need specially designed implants or prosthesis. In addition, many modification methods have been introduced to enhance the bioactivity and antibacterial property of porous Ta with promising in vitro and in vivo research results. In any case, choosing suitable patients is of great importance to guarantee surgical success after porous Ta insertion.

Histopathological Findings of Failed Free Vascularized Fibular Grafting for Osteonecrosis of the Femoral Head after Long-Term Follow-Up

Purpose

The aim of this study was to report the histopathology of failed free vascularized fibular grafting (FVFG) for osteonecrosis of the femoral head (ONFH) after a mean follow-up of 11.5 years (ranged from 10.6 to 14.2 years).

Methods

Six hips of 5 patients with a history of steroid use, aged 34–67 years, were in stage II of ONFH as classified by the Ficat and Arlet classification at the time of FVFG treatment. Grafting failure led to osteoarthritis of the hip joint during a mean of 11.5 years of follow-up. Femoral head specimens were first evaluated macroscopically. Bone specimens were sectioned into long strips, divided into necrotic, transitional, and healthy zones, and then prepared for nondecalcified and decalcified histopathological examination using hematoxylin and eosin (HE) staining, Goldner's trichrome staining, and immunofluorescence (IF) staining.

Results

Femoral head articular cartilage surfaces appeared thin, opaque, and partially cartilaginous missing, with gradual collapse detected in weight-bearing areas. The interface with the fibular graft showed well union, with no obvious gaps between graft and host bone, as observed macroscopically. The necrotic area was filled with fibular graft, cancellous bone, and cartilaginous or soft tissue invasion. Histopathology results revealed well integration between fibular graft and host bone, with thickened trabecular bone. Gaps occurred in transitional and healthy zones. In the necrotic zone, cartilaginous or soft tissue invasion occurred, while thin or missing articular cartilage exposed subchondral bone to hip joint surfaces. By IF counterstaining with CD-31 and α-SMA, blood vessel transplanted during fibular grafting could be clearly observed along the graft from healthy to necrotic zones. In the necrotic zone, blood vessels presented obviously and spread into the surrounding area of the graft tip.

Conclusion

After FVFG procedure with a mean follow-up of 11.5 years, fibular grafts retained their integrity as viable, vascularized, cortical bone that fused well with host bone and formed thickened trabecular bone surrounding the surface of the graft. However, the revascularization of FVFG's blood vessels spreading from the tip of the fibular graft into subchondral area of necrotic lesion did not improve significantly in these failure cases. The local necrotic lesion failed to be repaired as healthy trabecular bone to buttress articular surface and was occupied by soft tissues.

Static, Dynamic and First-Pass MR Imaging of Musculoskeletal Lesions Using Gadodiamide Injection

Forty-five patients with known or suspected musculoskeletal tumors were examined with static and dynamic MR imaging to evaluate the safety, tolerability and diagnostic utility of gadodiamide injection and to assess the diagnostic value of dynamic MR imaging and parametric “first-pass” (FP) images. The proportion of patients presenting more diagnostic information on the contrast-enhanced compared to the precontrast spin-echo examinations was determined. The dynamic enhancement characteristics were evaluated with time-intensity curves and parametric images of the FP enhancement rate. The tolerance of gadodiamide injection was good. Contrast enhancement was useful for delineating tumor from muscle, and differentiating viable from necrotic tissue and cystic from solid lesions. Malignant tumors showed a significantly higher slope value, earlier onset of enhancement, and higher maximum enhancement than benign lesions. However, slope values could not be used to predict the malignant potential of a lesion, due to overlap between highly vascular benign and low vascular malignant lesions. By displaying highly vascular areas, parametric FP images provided useful information on the most active part in a tumor before biopsy and for assessing the incorporation of bone-chip allografts. Static, dynamic and FP MR imaging using gadodiamide injection appears safe and provides useful information for diagnosis, biopsy and follow-up of musculoskeletal lesions.

Early failures of porous tantalum osteonecrosis implants: a case series with retrieval analysis

BACKGROUNDS

Porous tantalum osteonecrosis implants have been used in femoral head necrosis for several years, while the clinical outcomes were mixed. As a joint-preserving surgery, early necrosis deterioration and conversion to total hip arthroplasy failed our expectation. We hence investigate an observational study with retrieval analysis to find out the underlying reasons.

METHODS

Thirteen patients were treated with core decompression and implantation of a tantalum rod. The cases were evaluated both functionally and radiologically. We retrieved and analyzed the micro-structural changes and the histopathologic features of four early failed femoral heads with scanning electron microscopy, histopathologic examination, and micro-CT scaning.

RESULTS

All implants were placed in proper positions. One-year survival rate was 64.29 % with a HSS score of 81.11 ± 15.62. Four patients converted to arthroplasty in a mean time of 305 days (0.84 years), with a HSS score of 43.75 ± 7.5 at the last follow-up. A liquid layer surrounded the tantalum implant was noted on MRI in all four failed cases. Volume render CT remodeling revealed interspace between the metal and bone. Scanning electron microscopy and histopathologic examination indicated sparse and isolated bone ingrowth into the implants. The remodeled trabecular bone and the increased density around the peri-implant area were illustrated with micro-CT scaning.

CONCLUSIONS

The deterioration of early failed tantalum implant exceeds the nature of osteonecrosis progression. Rather than insufficient mechanical support resulting in improper position and invalid bone ingrowth, nullification of core decompression and consequential intra-osseous pressurization probably led to early failure of porous tantalum osteonecrosis implants.

Avascular necrosis of the femoral head after osteosynthesis of femoral neck fracture

The reported incidence of avascular necrosis after femoral neck fracture fixation varies widely, and there is no consensus regarding its risk factors. We evaluated the incidence of avascular necrosis of the femoral head with the use of contemporary techniques for femoral neck fracture fixation. We then sought to determine what potential risk factors influenced the development of avascular necrosis.Between 1990 and 2005, one hundred sixty-three intracapsular femoral neck fractures in 163 patients were treated with internal fixation at our level-I trauma center. All patients were monitored until conversion to total hip arthroplasty or for a minimum of 2 years postoperatively. Ten patients (10 hips) died and 7 patients (7 hips) were lost to follow-up. The remaining 146 patients (146 hips) had a mean 5.2 years of follow-up (range, 3 months to 17 years). The incidence of avascular necrosis was 25.3% (37 hips). The average time to diagnosis of avascular necrosis was 18.8 months (range, 3-47 months). Patient sex, age, interval from injury to surgery, and mechanism of injury were statistically not associated with the development of avascular necrosis. The quality of fracture reduction, adequacy of fixation, degree of displacement, and comminution of the posterior cortex were significantly associated. After we controlled for patient and radiographic characteristics, multivariate analyses indicated that the important predictors for avascular necrosis are poor reduction (odds ratio=13.889) and initial displacement of the fracture (odds ratio=4.693).

Vascularized bone allotransplantation: current state and implications for future reconstructive surgery

This article focuses on current advances in musculoskeletal tissue allotransplantation, including strategies for maintaining tissue viability in the face of histocompatibility mismatch and resulting acute and chronic rejection responses. In particular, it introduces a novel concept developed in the authors' laboratory and currently under evaluation that may obviate the problem of chronic rejection. The authors have used therapeutic angiogenesis to develop a host-derived neoangiogenic circulation that maintains blood flow regardless of rejection. The replacement of the allogeneic vessels together with bone remodeling from host-derived cells eventually may largely replace the allogeneic osteocytes and bone with native bone.

Failure of free vascularized fibular graft for osteonecrosis of the femoral head: a histopathologic study of 6 cases

The rationale for the use of free vascularized fibular graft for osteonecrosis of the hip is based on the assumption that the graft will provide support and blood supply to the osteonecrotic head. We report the histopathologic features of 6 consecutive osteonecrotic heads with failed vascularized fibular grafts. Three grafts were partially viable, and 3 were necrotic. The medullary canal was completely necrotic in 4 grafts. A thin layer of new, viable periosteal bone and bone remodeling was present at the surface of 4 grafts. New bone applied to the surface of the graft, especially in the 3 necrotic ones, suggests that the new bone originated from the host bed and not from the graft. Therefore, the risks and benefits of the vascular anastomosis, which in these cases provided no viability to the graft, should be re-evaluated. These findings were observed in failed cases and cannot be extrapolated to successful ones.

Free vascularized fibular grafts have a high union rate in atrophic nonunions

Free vascularized fibular grafting currently is an extremely useful tool in the armamentarium of the orthopaedic, reconstructive surgeon. Certain problematic nonunions, aseptic or infected, have to be treated by vascularized bone grafts when previous operations are not successful. The common characteristics of these nonunions are several previous operations and fixations, bone atrophy and damage of the surrounding soft tissue, and frequently focal, active infection. After the bone and soft tissue debridement, the bony defect is bridged by a vascularized fibula strut. Depending on the recipient bone, different methods of internal fixation can be used, usually plates and external fixators. Free vascularized fibular grafts in recalcitrant, atrophic nonunions provide a high success rate. According to the results, this is a safe, reliable method that is indicated when a fracture does not heal after several surgeries, when there is an associated bone lost, and when infection is present.

Avascular necrosis of the femoral head after femoral neck fracture

Trauma-induced avascular necrosis of the femoral head represents the most common femoral head aseptic necrosis. An alteration in blood supply to the femoral head is the cause of the vascular necrosis. Another mechanism in the genesis of femoral head necrosis is the tamponade effect. Femoral head necrosis may be asymptomatic for a long time, even in patients in whom late segmental collapse already is present. Radiography does not allow diagnostic reliability until 6 months after fracture. The presence of a low signal intensity band away from the fracture line on magnetic resonance images clearly delimits the necrotic area. Once segmental collapse has developed, the diagnosis becomes simple using plain radiographs. The treatment of established femoral necrosis complicating fractures of the upper end of the femur is approached as a therapeutic problem lacking an optimal solution. The main therapeutic options are femoral head-preserving procedures and joint reconstruction. Among the procedures that preserve the femoral head are joint unloading, femoral head core decompression, electric stimulation, osteotomy, and bone grafting. Joint reconstruction procedures including cup arthroplasty, hemiresurfacing, total hip resurfacing, femoral head replacement, femoral head endoprosthesis, and total arthroplasty will be reviewed.

Treatment of osteonecrosis of the femoral head with free vascularized fibular grafting. A long-term follow-up study of one hundred and three hips

The results for 103 consecutive hips (eighty-nine patients) that had been treated with free vascularized fibular grafting because of symptomatic osteonecrosis of the femoral head were reviewed in a prospective study. The disease was associated with consumption of alcohol in 30 percent of the hips, use of steroids in 17 percent, trauma in 13 percent, and Perthes disease in 3 percent; in the remaining 38 percent, the condition was idiopathic. All patients, except for one who died of unrelated causes 4.5 years after the operation, were followed for at least five years. By the time of the most recent follow-up evaluation, a total arthroplasty had been performed in thirty-one hips: two of the nineteen that were in stage II, according to the criteria of Marcus et al., at the time of the operation; five (23 percent) of the twenty-two that were in stage III; seventeen (43 percent) of the forty that were in stage IV; and seven (32 percent) of the twenty-two that were in stage V. Kaplan-Meier survivorship analyses demonstrated that the probability of conversion to a total hip arthroplasty within five years after free vascularized fibular grafting was 11 percent for the stage-II hips, 23 percent for the stage-III hips, 29 percent for the stage-IV hips, and 27 percent for the stage-V hips. There was a trend toward a lower rate of conversion to a total hip arthroplasty in patients who were less than thirty years old, but this difference did not reach significance (p = 0.06). No association was found between a causative factor and the probability of conversion to a total hip arthroplasty. The average Harris hip scores had improved at the latest follow-up evaluation, compared with the preoperative values (p < 0.001). For the stage-II hips, the average score improved from 56 to 80 points; for the stage-III hips, from 52 to 85 points; for the stage-IV hips, from 41 to 76 points; and for the stage-V hips, from 36 to 75 points. An outcome questionnaire, completed for 73 percent of the hips, revealed that 59 per cent of the hips that had not been subsequently treated with an arthroplasty did not limit or only slightly limited the patient's ability to carry out daily activities, and 62 percent did not limit or only slightly limited the patient's ability to work.(ABSTRACT TRUNCATED AT 400 WORDS)