The Journal of bone and joint surgery. American volume
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J Bone Joint Surg Am · Oct 2009
Biomechanical consequences of a tear of the posterior root of the medial meniscus. Surgical technique.
Tears of the posterior root of the medial meniscus are becoming increasingly recognized. They can cause rapidly progressive arthritis, yet their biomechanical effects are not understood. The goal of this study was to determine the effects of posterior root tears of the medial meniscus and their repairs on tibiofemoral joint contact pressure and kinematics. ⋯ This study demonstrated significant changes in contact pressure and knee joint kinematics due to a posterior root tear of the medial meniscus. Root repair was successful in restoring joint biomechanics to within normal conditions.
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J Bone Joint Surg Am · Oct 2009
Comparative StudyCervical disc arthroplasty compared with arthrodesis for the treatment of myelopathy. Surgical technique.
Although there have been case reports describing the use of cervical disc arthroplasty for the treatment of myelopathy, there is a concern that motion preservation may maintain microtrauma to the spinal cord, negatively affecting the clinical results. As we are not aware of any studies on the use of arthroplasty in this scenario, we performed a cross-sectional analysis of two large, prospective, randomized multicenter trials to evaluate the efficacy of cervical disc arthroplasty for the treatment of myelopathy. ⋯ We found that patients in both the arthroplasty and arthrodesis groups had improvement following surgery; furthermore, improvement was similar between the groups, with no worsening of myelopathy in the arthroplasty group. While the findings at two years postoperatively suggest that arthroplasty is equivalent to arthrodesis for the treatment of cervical myelopathy for a single-level abnormality localized to the disc space, the present study did not evaluate the treatment of retrovertebral compression as occurs in association with ossification of the posterior longitudinal ligament, and we cannot comment on the treatment of this condition.
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J Bone Joint Surg Am · Oct 2009
Comparative StudyTreatment of scaphoid waist nonunions with an avascular proximal pole and carpal collapse. Surgical technique.
Surgically, it is difficult to achieve union of a scaphoid nonunion that is associated with osteonecrosis of the proximal pole, and those with carpal collapse are especially difficult to treat. A variety of vascularized bone grafts can be used. The purpose of this study was to compare the effectiveness of two types of vascularized bone graft -- a distal radial pedicle graft and a free vascularized medial femoral condyle graft -- in the treatment of scaphoid waist nonunions associated with proximal pole osteonecrosis and carpal collapse. ⋯ A vascularized interposition graft from the medial femoral condyle is the recommended vascularized bone graft for the surgical treatment of scaphoid waist nonunion with avascularity of the proximal pole and carpal collapse.
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J Bone Joint Surg Am · Oct 2009
Comparative StudyThe effect of postoperative passive motion on rotator cuff healing in a rat model.
Surgical repairs of torn rotator cuff tendons frequently fail. Immobilization has been shown to improve tissue mechanical properties in an animal model of rotator cuff repair, and passive motion has been shown to improve joint mechanics in animal models of flexor tendon repair. Our objective was to determine if daily passive motion would improve joint mechanics in comparison with continuous immobilization in a rat rotator cuff repair model. We hypothesized that daily passive motion would result in improved passive shoulder joint mechanics in comparison with continuous immobilization initially and that there would be no differences in passive joint mechanics or insertion site mechanical properties after four weeks of remobilization. ⋯ In this model, immediate postoperative passive motion was found to be detrimental to passive shoulder mechanics. We speculate that passive motion results in increased scar formation in the subacromial space, thereby resulting in decreased range of motion and increased joint stiffness. Passive motion had no effect on collagen organization or tendon mechanical properties measured six weeks after surgery.