Wellington K. Hsu

Adjacent segment degeneration in the lumbar spine.

BACKGROUND A primary concern after posterior lumbar spine arthrodesis is the potential for adjacent segment degeneration cephalad or caudad to the fusion segment. There is controversy regarding the subsequent degeneration of adjacent segments, and we are aware of no long-term studies that have analyzed both cephalad and caudad degeneration following posterior arthrodesis. A retrospective investigation was performed to determine the rates of degeneration and survival of the motion segments adjacent to the site of a posterior lumbar fusion. METHODS Two hundred and fifteen patients who had undergone posterior lumbar arthrodesis were included in this study. The study group included 126 female patients and eighty-nine male patients. The average duration of follow-up was 6.7 years. Radiographs were analyzed with regard to arthritic degeneration at the adjacent levels both preoperatively and at the time of the last follow-up visit. Disc spaces were graded on a 4-point arthritic degeneration scale. Correlation analysis was used to determine the contribution of independent variables to the rate of degeneration. Survivorship analysis was performed to describe the degeneration of the adjacent motion segments. RESULTS Fifty-nine (27.4%) of the 215 patients had evidence of degeneration at the adjacent levels and elected to have an additional decompression (fifteen patients) or arthrodesis (forty-four patients). Kaplan-Meier analysis predicted a disease-free survival rate of 83.5% (95% confidence interval, 77.5% to 89.5%) at five years and of 63.9% (95% confidence interval, 54.0% to 73.8%) at ten years after the index operation. Although there was a trend toward progression of the arthritic grade at the adjacent disc levels, there was no significant correlation, with the numbers available, between the preoperative arthritic grade and the need for additional surgery. CONCLUSIONS The rate of symptomatic degeneration at an adjacent segment warranting either decompression or arthrodesis was predicted to be 16.5% at five years and 36.1% at ten years. There appeared to be no correlation with the length of fusion or the preoperative arthritic degeneration of the adjacent segment.

Prevention of Venous Thromboembolic Disease After Total Hip and Knee Arthroplasty

Patients undergoing total hip and knee arthroplasty are at increased risk for the development of venous thromboembolic disease, and there is general agreement that these patients require prophylaxis. The selection of a prophylactic agent involves a balance between efficacy and safety and often needs to be individualized for specific patients and institutions. Despite extensive research, the ideal agent for prophylaxis against deep venous thrombosis has not been identified. The results of randomized trials indicate that low-molecular-weight heparin, warfarin, and fondaparinux are the most effective prophylactic agents after total hip arthroplasty and that low-molecular-weight heparin, warfarin, fondaparinux, and pneumatic compression boots are the most effective agents after total knee arthroplasty. The duration of prophylaxis against deep venous thrombosis after total hip and knee arthroplasty remains controversial. Prophylaxis should be continued beyond hospital discharge. In the future, the determination of the duration of prophylaxis will be based on the risk stratification of individual patients. The practice of discharging patients from the hospital without prophylaxis, even when the decision is based on negative results of procedures that screen for the presence of deep venous thrombosis, is not cost-effective.

Influence of BMPs on the Formation of Osteoblastic Lesions in Metastatic Prostate Cancer

The purpose of this study was to evaluate the role of BMPs on the formation of metastatic prostate cancer lesions to bone. Our results show that BMPs influence the development and progression of osteoblastic lesions and suggest that therapies that inhibit BMP activity may reduce the formation and progression of osteoblastic lesions.

Characterization of Osteolytic, Osteoblastic, and Mixed Lesions in a Prostate Cancer Mouse Model Using 18F-FDG and 18F-Fluoride PET/CT

The combination of small-animal PET/CT scans and conventional imaging methods may enhance the evaluation of in vivo biologic interactions of murine models in the study of prostate cancer metastasis to bone. Methods: Small-animal PET/CT scans using 18F-fluoride ion and 18F-FDG coregistered with high-resolution small-animal CT scans were used to longitudinally assess the formation of osteoblastic, osteolytic, and mixed lesions formed by human prostate cancer cell lines in a severe combined immunodeficient (SCID) mouse tibial injection model. These scans were correlated with plain radiographs, histomorphometry, and soft-tissue measurements. Results: Small-animal PET/CT scans were able to detect biologic activity of cells that induced an osteoblastic lesion 2 wk earlier than on plain radiographs. Furthermore, both the size and the activity of the lesions detected on PET/CT images significantly increased at each successive time point (P < 0.05). 18F-FDG lesions strongly correlated with soft-tissue measurements, whereas 18F-fluoride ion activity correlated with bone volume measured on histomorphometric analysis (P < 0.005). Osteolytic lesions were successfully quantified using small-animal CT, whereas lesion sizes measured on 18F-FDG PET scans also strongly correlated with soft-tissue tumor burden (P < 0.05). In contrast, for mixed lesions, 18F-fluoride ion and 18F-FDG PET/CT scans detected only minimal activity. Conclusion: 18F-FDG and 18F-fluoride ion PET/CT scans can be useful tools in characterizing pure osteolytic and osteoblastic lesions induced by human prostate cancer cell lines. The value of this technology needs further evaluation to determine whether these studies can be used effectively to detect more subtle responses to different treatment regimens in animal models.

The rationale for cervical disc arthroplasty

Although the concepts of total disc arthroplasty were first described in 1966, only recently has the spine community considered its routine use in the cervical spine. The tenets of motion preservation have been pervasive in orthopaedic surgery and, for this reason, many researchers have advocated for this approach in the treatment of spinal disorders. Anterior cervical fusions have led to excellent clinical results; however, many patients require further reoperations and may have long-term deterioration of their symptoms. The preliminary data from randomized controlled trials involving both cervical spine total disc arthroplasty and fusion cohorts have been encouraging in establishing its safety, efficacy, and potential avoidance of adverse events in the treatment of radiculopathy and/or myelopathy. This manuscript will review the rationale behind the use of a cervical disc prosthesis.

Wound complications from idiopathic clubfoot surgery: a comparison of the modified Turco and the Cincinnati treatment methods.

Purpose: Treatment protocols using the Turco and the Cincinnati incisions are widely used for the surgical correction of clubfoot deformity. However, it is unclear which surgical approach leads to fewer wound problems. We therefore sought to determine which treatment method led to a lower incidence of wound complications. Study Design: A retrospective chart review of 217 consecutive patients (308 feet) who underwent a primary posteromedial release for the treatment of idiopathic clubfoot under the age of 24 months via either the modified Turco or Cincinnati treatment methods was used to document the incidence of postoperative wound complications. The modified Turco protocol involved immediate postoperative casting in neutral, whereas the Cincinnati method involved staged casting with the foot initially in equinus, then to neutral with a cast change 7 days later. Results: A significantly lower incidence of wound complications was seen in the Cincinnati treatment group when compared with the modified Turco treatment method (6.9% vs 19.6%, respectively, P < 0.003). When patients were stratified based on immediate versus staged postoperative casting methods, there was a significantly lower incidence of wound complications (P < 0.05) in feet in the Cincinnati treatment group versus the modified Turco treatment method; however, the statistical populations were markedly unequal. Among all feet treated with the Cincinnati method, patients who underwent a staged cast change had significantly fewer wound problems when compared with those who underwent immediate casting with the foot in neutral (5.1% vs 16.7%, respectively, P < 0.04). Conclusions: In the surgical correction of idiopathic clubfoot, the incidence of wound complications is significantly decreased with the use of the Cincinnati treatment method rather than the modified Turco treatment protocol. Whether this effect is a result of the incision or the postoperative casting protocol is unclear.

Thromboprophylaxis after hip fractures

Summary: Hip fractures are becoming increasingly common in the United States as the elderly population grows. In addition to cardiopulmonary and other medical complications, hip fracture patients are at extremely high risk for the development of venous thromboembolism (VTE). Although well-designed clinical studies analyzing the efficacy and safety of a variety of therapeutic modalities has been performed, an ideal prophylactic agent for VTE after hip fracture surgery has yet to be identified. Given the fragility of most patients with hip fractures, the choice of prophylaxis must be made carefully to balance the efficacy of the agent against the risks of postoperative bleeding. The purpose of this review is to summarize the literature regarding diagnosis and treatment of VTE after hip fractures.