Archives of orthopaedic and trauma surgery
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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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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.
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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
Unexpected resection of soft-tissue sarcoma. More mutilating surgery, higher local recurrence rates, and obscure prognosis as consequences of improper surgery.
Sixteen referred patients were reviewed after excision of an unexpected soft-tissue sarcoma of the extremities. Eight tumors were located in the muscle deep to the fascia, and 8 lesions exceeded the size of 5 cm. The lack of awareness by the primary physician towards the possibility of a malignant lesion was striking, although 11 of 16 tumors presented as a newly formed mass. ⋯ Physicians' alertness towards the possible malignancy of an enlarging mass cannot be overemphasized. Evaluation by adequate imaging techniques, biopsy, and definitive resection and reconstruction should be performed by an oncologically trained orthopaedic surgeon. Inadequate primary excision leads to a high local recurrence rate and more mutilating surgery and obscures the long-term prognosis.