Risk of Post-TKA Acute Myocardial Infarction in Patients With a History of Myocardial Infarction or Coronary Stent.

BACKGROUND: Acute myocardial infarction (AMI) is one of the most important perioperative complications of total knee arthroplasty (TKA). Although risk-stratification tools exist for the prediction of cardiac complications including AMI after noncardiac surgery, such stratification does not differentiate the patients with a coronary stent alone, AMI without a stent, or AMI with a stent. The risk of postoperative AMI in these patient groups may vary. Several studies have recommended suitable times for noncardiac surgery in patients with a coronary stent; however, they do not differentiate between the patients with AMI and no AMI. The suitable time of noncardiac surgery for patients with AMI and stent may vary from those with a stent alone. Moreover, a study to evaluate the risk of AMI within 1 year in an Asian population with a history of AMI or coronary stent who underwent TKA has not been reported. QUESTIONS/PURPOSES: (1) What are the risks of AMI within 1 year of TKA in patients who have had a stent alone, AMI without a stent, or AMI with a stent as compared with patients without an AMI/stent? (2) For patients with AMI/stent placement, when can TKA be performed where the risk of subsequent AMI normalizes? (3) What comorbidities are associated with post-TKA AMI? (4) Is the risk of AMI within 1 year after surgery in patients undergoing TKA without a history of AMI/stent higher than that in patients with no surgery? METHODS: This study is a retrospective study of the medical claim records of 128,216 patients who underwent TKA between 1997 and 2010 in Taiwan. The records were retrieved from the research database of the Bureau of National Health Insurance in Taiwan, which maintains the records of 99.68% of the Taiwan population. The patients who had a history of AMI or coronary stent placement within the year before TKA were compared with the patients who had not experienced AMI or stent placement before TKA. The control subjects were matched according to sex, age, Charlson score, and year of surgery. There were 2413 patients in each group. The patients with a history of AMI or stent placement and the timing of TKA after coronary event were further stratified as with a coronary stent alone, AMI without a stent, and AMI with a stent. The effects of the comorbidities of renal failure, diabetes, liver failure, and hypertension were also analyzed individually. The risk of AMI within 1 year after TKA was investigated using bivariate analysis and the Cox proportional hazard model. To compare the risk of AMI within 1 year of surgery in the patients with a history of TKA and no AMI/stent with the population without a history of surgery, a similar bivariate analysis and the Cox proportional hazard model were applied to their matched case and control groups, each containing 110,980 patients. RESULTS: In the adjusted model, using no AMI/stent before TKA as a reference, patients having undergone AMI + stent had the highest risk (hazard ratio [HR], 5.23; 95% confidence interval [CI], 1.81-15.14; p = 0.002), AMI alone without a stent had less risk (HR, 4.88; 95% CI, 1.49-16.01; p = 0.009), and stent alone with AMI had the lowest risk (HR, 3.16; 95% CI, 1.29-7.71; p = 0.012). In all patients, risk of AMI after TKA was not different than reference values after 1 year of initial AMI or stent (stent: HR, 1.67; 95% CI, 0.71-3.94; p = 0.239; AMI: HR, 1.88; 95% CI, 0.42-8.49; p = 0.412; AMI + stent: HR, 1.91; 95% CI, 0.53-6.89; p = 0.321). The risk of post-TKA AMI was elevated within 1 year of the previous episode of AMI/stent (0-180 days: HR, 8.42; 95% CI, 3.03-23.41; p < 0.001; 181-365 days: HR, 7.52; 95% CI, 2.47-22.88; p < 0.001). Only chronic renal failure under hemodialysis was associated with increased risk of AMI within 1 year of TKA (adjusted HR, 4.34; 95% CI, 1.22-15.43; p = 0.023). Patients undergoing TKA with no history of AMI/stent had a lower risk of AMI within 1 year of TKA compared with the patients with no history of surgery (adjusted HR, 0.92; 95% CI, 0.86-0.99; p = 0.016). CONCLUSIONS: This study found the risk of post-TKA AMI remains high within 1 year in patients with a history of AMI/stent. It is recommended that an elective TKA should be performed at least 1 year after an episode of AMI or stent placement. Stents do not provide protection against post-TKA AMI within 6 months of the AMI and patients with AMI + stent have a higher risk of AMI than those with only AMI. Patients of AMI/stent on hemodialysis have a very high risk of post-TKA AMI. However, the risk of AMI is lower in post-TKA patients compared with those with no TKA. LEVEL OF EVIDENCE: Level III, prognostic study.

Temporal trends in primary and revision total knee and hip replacement in Taiwan.

BACKGROUND: Total joint replacement (TJR) accounts for a substantial proportion of the total expenditures for health care. Efficient utilization of health resources requires information regarding the trends of TJR. This study investigated the association of TJR with the demographic characteristics in Taiwan from 1998 to 2009. It also estimated the demand for total knee replacement (TKR) and total hip replacement (THR) in the next two decades. METHODS: International Classification of Diseases-9 (ICD-9) procedure codes were used to identify the data for primary and revision TKRs and THRs between the years 1998 and 2009 from Taiwan's National Health Insurance Research Database. Age- and sex-specific rates of such procedures were calculated. The trend in TJR rate and its future estimation were studied with regression analyses. RESULTS: From 1998 to 2009, the number of primary TKRs increased by 99.1% and that of primary THRs increased by 11.3%. The number of revision TKRs increased by 3.1% and that of revision THRs decreased by 13.2%. Compared with their respective rates in 2005, the rates of primary TKR and primary THR were projected to increase by 508.2% and 69.7%, respectively, in 2030. The rate of revision TKR was predicted to increase by 75.3% and that of revision THR to decrease by 36.1%. CONCLUSION: This study gives an insight into the current status burden of TJR in Taiwan. TJR rate projection would be useful for future planning of budget and resources for TJR in Taiwan.

Salvage of knee joint tumor prosthesis using turnover reverse-flow descending branch of lateral circumflex femoral artery as recipient vessel for the free ALT flap: a case report.

To report an unusual case using free anterolateral thigh (ALT) fasciocutaneous flap to salvage a knee joint tumor prosthesis. The turnover reverse-flow descending branch of the ipsilateral lateral circumflex femoral artery (LCFA) was successfully used as a recipient vessel for the contralateral free ALT flap. A 30-year-old male patient with high-grade and fibroblastic-type osteogenic sarcoma at the right proximal tibia received a tumor resection and tumor prosthesis to salvage the right knee joint. No local antegrade recipient vessels were available near the defect at the right knee. No sizable perforator could be found when trying to harvest the reverse ipsilateral ALT flap. The turnover reverse-flow descending branch of the ipsilateral LCFA and its concomitant veins were used as recipient vessels to supply the contralateral free ALT flap. The flap survived well without obvious venous congestion or sequela. The turnover reverse-flow descending branch of the LCFA and its concomitant veins can be successfully used as recipient vessels to supply a free ALT flap.

Intradural cement leakage: a devastatingly rare complication of vertebroplasty.

STUDY DESIGN: The aim of this case report is to examine the devastating complication that may follow vertebroplasty. OBJECTIVES: To report 1 case of intradural cement leakage caused by percutaneous vertebroplasty with polymethyl methacrylate. SUMMARY OF BACKGROUND DATA: Cement leakage is not a rare complication of vertebroplasty. But intradural cement leakage is rare. We herein report a rare but devastating complication of vertebroplasty. METHODS: A 90-year-old woman with a T12 and L1 osteoporotic compression fracture underwent percutaneous vertebroplasty using polymethyl methacrylate at local hospital. A literature search was performed to assess complications of vertebroplasty. RESULTS: She was transferred to our hospital due to abdominal pain. Physical examination revealed distended abdomen with local tenderness and weakness of both legs (muscle power: Grade 2). Plain radiograph of abdomen showed ileus and intradural cement leakage. Conservative treatment with nasogastric decompression was done, and her abdominal pain subsided 1 week later. CONCLUSIONS: Percutaneous vertebroplasty with polymethyl methacrylate is relatively safe, but it still should be proceeded under careful safeguard. The needle tip should not cross the medial border of the pedicle on the anteroposterior view before it has crossed the posterior cortex of the vertebral body on the lateral view. Good quality of image monitoring and clear visualization of cement should be helpful to prevent complications.

Evaluation of chitosan-alginate-hyaluronate complexes modified by an RGD-containing protein as tissue-engineering scaffolds for cartilage regeneration.

In this study, a series of natural biodegradable materials in the form of chitosan (C)-alginate (A)-hyaluronate (H) complexes are evaluated as tissue-engineering scaffolds. The weight ratio of C/A is 1 : 1 or 1 : 2. Sodium hyaluronate is mixed in 2%. The complexes can be cast into films or fabricated as scaffolds. Their surface can be further modified by an Arg-Gly-Asp (RGD)-containing protein, a cellulose-binding domain-RGD (R). Cytocompatibility tests of the films are conducted using immortalized rat chondrocyte (IRC) as well as primary articular chondrocytes harvested from rabbits. The neocartilage formation in cell-seeded scaffolds is examined in vitro as well as in rabbits, where the scaffolds are implanted into the defect-containing joints. The results from cytocompatibility tests demonstrate that R enhances cell attachment and proliferation on C-A and C-A-H complex films. Complex C1A1HR (C : A = 1 : 1 with H and R) has better performance than the other formulation. Cells retain their spherical morphology on all C-A and C-A-H complexes. The in vitro evaluation of the seeded scaffolds indicates that the C1A1HR complex is the most appropriate for 3-D culture, manifested by the better cell growth as well as higher glycosaminoglycan and collagen contents. When the chondrocyte scaffolds are implanted into rabbit knee cartilage defects, partial repair is observed after 1 month in C1A1HR as well as in C1A1 (C : A = 1 : 1 without H and R) scaffolds. The defects are completely repaired in 6 months when C1A1HR constructs are implanted. It is concluded that C1A1HR is a potential tissue-engineering scaffold for cartilage regeneration.

Secondary chondrosarcoma in osteochondroma: report of 107 patients.

Secondary chondrosarcomas are rare; recognition and diagnosis are difficult. Slow growth and late recurrence require long-term followup to understand the clinical course. In the current study, 107 patients had secondary chondrosarcoma arising in a solitary osteochondroma (61 patients) or multiple exostoses (46 patients). All histologic slides were reviewed without knowledge of the outcome, and radiologic studies were available for review in 71 cases. Patients with secondary chondrosarcoma were one to two decades younger than those with primary chondrosarcoma. Male preponderance and a predilection for flat bones were observed. The radiologic signs of sarcomatous degeneration included irregularity of the margin, inhomogeneous mineralization, and an associated soft tissue mass. The tumors generally were well-differentiated. Only 10 tumors were classified as Grade 2. Five-year and 10-year local recurrence rates were 15.9% and 17.5%, respectively, and 5- and 10-year mortality rates were 1.6% and 4.8% for patients having initial treatment at the authors' institution. Metastasis developed in five patients: in the lung in four patients and in the groin region in one patient. Most patients who died of tumor died of local recurrence. Wide excision had the lowest local recurrence rate. With successful surgical treatment, patients may have long-term disease-free survival.