Use of a pneumatic tourniquet in total knee arthroplasty increases the risk of distal deep vein thrombosis: A prospective, randomized study.

BACKGROUND: There has been controversy regarding the incidence of deep vein thrombosis (DVT) after total knee arthroplasty (TKA) with or without the use of a tourniquet. The aim of this randomized, prospective study was to clarify the effects of tourniquet use on DVT in TKA. METHODS: The subjects were 109 patients scheduled to undergo TKA from April 2008 to March 2009 before the establishment of the American Association of Orthopedic Surgeons (AAOS) practice guidelines. They were randomized into two groups: 51 patients in the tourniquet group (group T) and 52 patients in the control group without a tourniquet (group C). We investigated the thrombotic presence using ultrasonography one week after surgery and compared both groups. RESULTS: There was no difference in the rate of proximal DVTs (P=0.63). However, the risk of distal DVT was significantly higher in group T than in group C (52.9% vs. 23.1%; P=0.002). CONCLUSIONS: Use of the tourniquet in TKA increased the risk of distal DVT.

Mobile-bearing total knee arthroplasty improves patellar tracking and patellofemoral contact stress: in vivo measurements in the same patients.

Controversies exist in clinical study concerning the effect of rotating platform on patellar tracking. The aim of this in vivo study was to compare tibial rotation, patellar tracking, and patellofemoral contact stress in mobile and fixed-bearing platform intraoperatively in the same knee. Sixty-six knees of posterior-stabilized total knee prostheses were evaluated using a computed tomography-guided navigation system. Medial shift and lateral tilt of patella were significantly smaller in mobile knee. Averaged maximum contact stress was significantly smaller in mobile knee than fixed knee. However, tibial rotation during flexion has no significant difference. This study showed that mobile platform total knee arthroplasty significantly improved patellar tracking and decreased patellofemoral contact stress.

The role of osteopontin in tendon tissue remodeling after denervation-induced mechanical stress deprivation.

It has been shown that musculoskeletal tissues undergo dynamic tissue remodeling by a process that is quite sensitive to the mechanical environment. However, the detailed molecular mechanism underlying this process remains unclear. We demonstrate here that after denervation-induced mechanical stress deprivation, tendons undergo dynamic tissue remodeling as evidenced by a significant reduction of the collagen fibril diameter. Importantly, the transient up-regulation of osteopontin (OPN) expression was characteristic during the early phase of tendon tissue remodeling. Following this dynamic change of OPN expression, matrix metalloproteinase (MMP)-13 expression was induced, which presumably accounts for the morphological changes of tendon by degrading tendon collagen fibrils. The modulation of MMP-13 expression by OPN was specific, since the expression of MMP-2, which is also known to be involved in tissue remodeling, did not alter in the tendons under the absence or presence of OPN. We also demonstrate that the modulation of MMP-13 expression by OPN is due to the signaling through cell surface receptors for OPN. Thus, we conclude that OPN plays a crucial role in conveying the effect of denervation-induced mechanical stress deprivation to the tendon fibroblasts to degrade the extracellular matrices by regulating MMP-13 expression in tendon fibroblasts.