Hydroxyapatite (HA) coating appears to be of benefit for implant durability of tibial components in primary total knee arthroplasty

Background It is unclear whether there is a clinical benefit to adding hydroxyapatite (HA) coatings to total knee implants, especially with the tibial component, where failure of the implant more often occurs. A systematic review of the literature was undertaken to identify all prospective randomized trials for determining whether the overall clinical results (as a function of durability, function, and adverse events) favored HA-coated tibial components.

Methods A comprehensive literature search was performed for the years 1990 to September 16, 2010. We restricted our search to randomized controlled trials involving participants receiving either an HA-coated tibia or other forms of tibial fixation. The primary outcome measures evaluated were durability, function, and acute adverse events.

Results Data from 926 evaluable primary total knee implants in 14 studies were analyzed. Using an RSA definition for durability, HA-coated tibial components (porous or press-fit) without screw fixation were less likely to be unstable at 2 years than porous and cemented metal-backed tibial components (RR = 0.58, 95% CI: 0.34–0.98; p = 0.04, I² = 39%, M-H random effects model). There was no significant difference in durability, as measured from revision and evaluated at 2 and 8–10 years, between groups. Also, functional status using different validated measures showed no significant difference at 2 and 5 years, no matter what measure was used. Lastly, there was no significant difference in adverse events. Limitations included small numbers of evaluable patients (≤ 50) in 7 of the 14 trials identified, and a lack of “hard” evidence of durability with need for replacement (i.e. frank failure, pain, or loss of functionality).

Interpretation In patients > 65 years of age, an HA-coated tibial implant may provide better durability than other forms of tibial fixation. Larger trials should be undertaken comparing the long-term durability, function, and adverse events of HA-coated implants with those of other porous-coated tibial implants in younger, more active OA patients.     

法洛氏四联症矫治术后中远期肺动脉高压

【】目的 报道一组法洛氏四联症矫治术后中远期肺动脉压力及阻力升高的病例。方法2009.01-2011.04间我院行法洛氏四联症矫治术共181例(我院181例接受法洛氏四联症矫治术患儿),随访2-5年怀疑患出现肺动脉高压者并对其行右心导管检查最终确诊19例,分析单纯TOF矫治术后产生肺动脉高压的因素。结果19例患者在随访的2-5年内,绝大多数没有未出现明显临床症状。WHO心功能评定I/II级17例,III/IV级2例。问卷调查Borg呼吸困难评分为1-7分,中位数为4分。BNP检查为(11-＞300000)pg/ml,BNP的中位数为266pg/ml。右心导管检查示不同程度的肺动脉压力和阻力上升升高,其中轻度肺动脉高压16例,占绝大多数,所有患者肺小动脉楔入压均正常(6-10mmHg),肺动脉-右心室连续测压压力阶差小于10mmHg,右房压力属正常范围(6-11mmHg)。部分患者同时行肺小动脉造影,没有发现肺动脉高压特征性改变。无急性肺血管扩张试验阳性者。讨论部分法洛氏四联症矫治术后患者中远期会出现肺动脉高压及全肺阻力升高,其机制目前并不十分确定清楚,可能是一个多因素交叉的复杂过程。     

Calibration of an instrumented treadmill using a precision-controlled device with artificial neural network-based error corrections

Instrumented treadmills (ITs) are used to measure reaction forces (RF) and center of pressure (COP) movements for gait and balance assessment. Regular in situ calibration is essential to ensure their accuracy and to identify conditions when a factory re-calibration is needed. The current study aimed to develop and calibrate in situ an IT using a portable, precision-controlled calibration device with an artificial neural network (ANN)-based correction method. The calibration device was used to apply static and dynamic calibrating loads to the surface of the IT at 189 and 25 grid-points, respectively, at four belt speeds (0, 4, 6 and 8 km/h) without the need of a preset template. Part of the applied and measured RF and COP were used to train a threelayered, back-propagation ANN model while the rest of the data were used to evaluate the performance of the ANN. The percent errors of F_z and errors of the P_x and P_y were significantly decreased from a maximum of −1.15%, −1.64 mm and −0.73 mm to 0.02%, 0.02 mm and 0.03 mm during static calibration, respectively. During dynamic calibration, the corresponding values were decreasing from −3.65%, 2.58 mm and −4.92 mm to 0.30%, −0.14 mm and −0.47 mm, respectively. The results suggest that the calibration device and associated ANN will be useful for correcting measurement errors in vertical loads and COP for ITs.