Archives of orthopaedic and trauma surgery
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Arch Orthop Trauma Surg · Jan 2000
Can skin surface pressure under a cast reveal intracompartmental pressure?
Although monitoring intracompartmental pressure (IP) under a cast is very important, it is not possible to measure it in every patient undergoing cast treatment. This study aims to answer the question of whether skin surface pressure (SSP) under a cast can reveal IP. A plaster cast was applied to a sculpted inflatable forearm model with dorsal and volar compartments. ⋯ The mean correlation coefficient was 0.973 (P = 0.000) (SD 0.024, range 0.916-0.997). Measuring the pressure between the skin and cast can monitor IP. SSP monitoring can help the physician, patient or parents in the follow-up of patients undergoing cast treatment.
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Arch Orthop Trauma Surg · Jan 2000
Mechanical properties of a rat patellar tendon stress-shielded in situ.
The effects of stress deprivation on the mechanical properties of the patellar tendon (PT) were studied using 14 albino rats. The PT was stress-shielded with cerclages on one side, while the contralateral patellar tendon served as a sham-operated control. After 10 weeks, paired load-strain as well as load-relaxation experiments were performed (11 and 3 specimen pairs, respectively). ⋯ The time constant significantly decreased in the stress-shielded specimens under 5 N loads, which may be considered 'physiological'. Tissue remodeling might explain the observed changes in the viscoelastic behaviour of the stress-shielded tendons. Loading, even in the physiological range of normal daily activity, may lead to an elongation of previously stress-shielded tendons or ligaments and consequently alter the behaviour of a joint.
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Several years ago, low-intensity pulsed ultrasound (frequency 1.5 MHz; signal burst width 200 micros; signal repetition frequency 1 KHz; intensity 30 mW/cm2) was shown to accelerate fresh fracture healing both clinically and experimentally. On the basis of a prescription use registry, this paper reports on the use of low-intensity pulsed ultrasound in the therapy of 951 delayed unions and 366 nonunions. The overall success rate for delayed unions was 91% (average healing time 129+/-2.7 days) and for nonunions 86% (average healing time 152+/-5.3 days). ⋯ Therefore, the results of these two populations support each other. Low-intensity pulsed ultrasound may provide a method of nonoperative treatment of great promise for healing disorders. Determination of ranking of this new method should be done within the near future.
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Arch Orthop Trauma Surg · Jan 2000
Posterior cruciate ligament and coupled posterolateral instability of the knee.
We wanted to investigate the role of the posterior cruciate ligament (PCL) in the knee's posterolateral stability and the magnitude of the coupled posterolateral instability with the knee examined at 90 degrees of flexion. The coupled posterolateral instability of the knee was studied by selective ligament cutting in cadaver knees set at 90 degrees. The coupled posterolateral displacement after cutting the PCL was 173% of the intact knee. ⋯ With an intact PCL, the posterolateral instability was very recognizable with the knee at 90 degrees of flexion, and injury to the PCL further increased the posterolateral instability and caused posterior translation of the knee. Therefore, examination for posterolateral instability of the knee should also be performed with the knee at 90 degrees of flexion, which is much easier to perform in a clinical setting. A positive posterior translation rather than posterolateral instability at different knee positions differentiates knees with combined PCL and posterolateral instability from knees with isolated posterolateral instability.
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Arch Orthop Trauma Surg · Jan 2000
Increased interleukin-8 (IL-8) expression is related to aseptic loosening of total hip replacement.
Aseptic loosening is an increasing problem in total hip replacement (THR). Chronic inflammatory reaction against implant wear particle results in collageno- and osteolysis, leading to loosening of the implant. Cytokines are known to play a major role in this particular inflammatory process. ⋯ The present study determines for the first time the cellular origin of IL-8 in aseptically loosened THRs and also quantitates the IL-8-producing cells in the periprosthetic tissue. The results reveal a high rise in IL-8 concentration in SLIM and in synovial tissues. This finding moves us one step forward in solving the complex network of multiple factors affecting loosening of hip implants.