Clinical Evaluation of Synovial Alpha Defensin and Synovial C-Reactive Protein in the Diagnosis of Periprosthetic Joint Infection.

BACKGROUND: Diagnosing periprosthetic joint infection after total joint arthroplasty is often challenging. The alpha defensin test has been recently reported as a promising diagnostic test for periprosthetic joint infection. The goal of this study was to determine the diagnostic accuracy of alpha defensin testing. METHODS: One hundred and eighty-three synovial alpha defensin and synovial fluid C-reactive protein (CRP) tests performed in 183 patients undergoing evaluation for periprosthetic joint infection were reviewed. Results were compared with the Musculoskeletal Infection Society (MSIS) criteria for periprosthetic joint infection. RESULTS: Alpha defensin tests were performed prior to surgical treatment for infection, and 37 of these patients who had these tests were diagnosed by MSIS criteria as having infections. Among this group, the alpha defensin test had a sensitivity of 81.1% (95% confidence interval [CI], 64.8% to 92.0%) and a specificity of 95.9% (95% CI, 91.3% to 98.5%). There were 6 false-positive results, 4 of which were associated with metallosis. There were 7 false negatives, all of which were associated with either draining sinuses (n = 3) or low-virulence organisms (n = 4). A combined analysis of alpha defensin and synovial fluid CRP tests was performed in which a positive result was represented by a positive alpha defensin test and a positive synovial fluid CRP test (n = 28). Among this group, the sensitivity was calculated to be 73.0% (95% CI, 55.9% to 86.2%) and the specificity was calculated to be 99.3% (95% CI, 96.2% to 99.9%). An additional combined analysis was performed where a positive result was represented by a positive alpha defensin test or positive synovial fluid CRP test (n = 64). Among this group, the sensitivity was calculated to be 91.9% (95% CI, 78.1% to 98.3%) and the specificity was calculated to be 79.5% (95% CI, 72.0% to 85.7%). CONCLUSIONS: Alpha defensin in combination with synovial fluid CRP demonstrates very high sensitivity for diagnosing periprosthetic joint infection, but may yield false-positive results in the presence of metallosis or false-negative results in the presence of low-virulence organisms. When both alpha defensin and synovial fluid CRP tests are positive, there is a very high specificity for diagnosing periprosthetic joint infection. LEVEL OF EVIDENCE: Diagnostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Paget Disease of Bone.

The current understanding of Paget disease of bone (PDB) has vastly changed since Paget described the first case in 1877. Medical management of this condition remains the mainstay of treatment. Surgical intervention is usually only used in fractures through pagetic bone, need for realignment to correct deformity in major long bones, prophylactic treatment of impending fractures, joint arthroplasty in severe arthritis, or spinal decompression in cases of bony compression of neural elements. Advances in surgical technique have allowed early return to function and mobilization. Despite medical and surgical intervention, a small subset of patients with PDB develops Paget sarcoma.

The role of cytokines in posttraumatic arthritis.

The development of arthritis after joint injury is commonly known as posttraumatic arthritis (PTA). The inciting traumatic event may range from cartilage contusion and bone bruise combined with meniscus or ligament tear, to intra-articular fracture. End-stage PTA is often indistinguishable from primary osteoarthritis. However, knowing the time of the inciting traumatic event in a patient with PTA provides an opportunity to understand the events following joint injury that lead to the progression of arthritis. Joint injury often leads to mechanical alterations in loading of the injured joint, and restoration of joint mechanics through surgical repair remains an important aspect of treatment. However, the accuracy of joint reduction by itself does not account for the variability in outcome following joint injury, as evidenced by the fact that PTA remains a significant clinical problem. Emerging research in animal models and human subjects indicates that several inflammatory cytokines and related inflammatory mediators are elevated following joint injury. Data from animal studies and early clinical trials suggest that early inhibition of the intra-articular inflammatory response may improve clinical outcomes.

Tissue engineering for the meniscus: a review of the literature.

The menisci disperse the load at the knee joint. Removal of the menisci can lead to osteoarthritis due to the higher load placed on the underlying cartilage. If they become injured it is therefore important to replace or regenerate the meniscus to prevent the progression of osteoarthritis. Many materials have been trialled to find a scaffold that can withstand the stresses and strains across the joint without causing any adverse effects. This review looks at these materials further to clarify the current position of tissue engineering for the meniscus and to highlight the areas where further research is needed. A scaffold which can produce high quality in vivo results in everyone has not yet been found.

Non-union of isolated displaced triquetral body fracture--a case report.

Triquetral fractures are the second most common carpal fractures. Triquetral body fractures are the less common type of triquetral fractures but they can be missed on plain radiographs and a non-union can be associated with considerable morbidity and reduction in functional activities. We report a unique case of displaced isolated triquetral body fracture that was initially missed on plain radiographs and resulted in non-union. The fracture non-union was diagnosed on magnetic resonance imaging and was treated successfully with open reduction and internal fixation using compression screws, without bone grafting, and early mobilisation of the wrist allowing a return to premorbid activity levels. To our knowledge, this has not been previously described in the literature. We advocate early clinical suspicion of triquetral fractures in patients with persistent ulnar-sided wrist pain following trauma, and early evaluation using computed tomography or magnetic resonance imaging.

Principles of fracture fixation in orthopaedic trauma surgery.

Fractures are common injuries and their management has evolved over the last 30 years with a greater propensity to treat fractures surgically. There have also been advances in the understanding of the principles of bone healing and the implications on implant choice. This article highlights the various surgical fixation devices available for the management of fractures and their underlying principles of action.

Non-steroidal anti-inflammatory drugs in orthopaedic and perioperative practice.

Non-steroidal anti-inflammatory drugs are powerful and effective anti-inflammatory, analgesic and anti-pyretic drugs. They are routinely used in orthopaedic conditions and in the perioperative setting. They are however associated with potentially life-threatening side-effects and it is important to appreciate these before these medicines are administered. There is evidence suggesting that these drugs adversely affect bone formation, and this has implications for their use in patients with fractures and other pathologies that involve bone remodelling.

Anticoagulation management in hip fracture patients on warfarin.

The management of patients admitted with a fracture requiring surgery who are taking warfarin anticoagulation is unclear. We examined the anticoagulation management for 33 hip fracture patients on warfarin at the time of admission. Hospital course and complications were recorded on all patients. The mean INR on admission was 3.2 and prior to surgery 2.2. Eight patients (24%) had percutaneous cancellous screws for an intracapsular fracture regardless of the admission INR. In 21 (64%) patients, surgery was delayed whilst the INR came down, with an average delay of 72 h from admission to surgery. No specific treatment to lower the INR, other than wait and watch policy adopted in 11 (33%) of these patients. Pharmacological methods used to reduce the INR were fresh frozen plasma in nine cases, and intravenous Vitamin K in four patients. One patient died from post-operative haematemesis and three died from medical complications unrelated to the warfarin therapy. There were no wound haematomas or other bleeding complications. Delaying surgery whilst waiting for the INR to fall to acceptable levels may result in significant delays to surgery and we would recommend a more aggressive policy to enable earlier surgery.