Periprosthetic malignancy as a mode of failure in total hip arthroplasty.

The presence of periprosthetic malignancy in proximity to arthroplasty implants has been infrequently reported. We present the clinical, radiographic, and pathological features of three patients in whom loosening and failure of total hip arthroplasties occurred secondary to malignant infiltration. They consisted of a 66-year-old man with the first presentation of metastatic gastric carcinoma as a periacetabular lytic lesion, a 64-year-old man presenting with femoral metastases from a previously undiagnosed lung carcinoma, and a 75-year-old woman presenting with a painless discharging thigh sinus around a total hip arthroplasty subsequently diagnosed as immunoblastic lymphoma. Malignant infiltration should be considered part of the differential diagnosis in aseptic and septic loosening of prosthetic implants. Joint aspiration and isotope bone scanning provide useful additional information before surgical intervention.

A prospective audit of blood usage post primary total knee arthroplasty.

The use of allogeneic blood is associated with many complications. A baseline audit performed in our institution in 2000 showed that 11% of patients undergoing primary total knee arthroplasty (TKA) required post-operative transfusion. Following this audit, patients undergoing primary TKA were no longer routinely cross matched, a Haemovigilance Nurse was employed in compliance with the National Blood Users Group guidelines, and post-operative cell salvage was introduced for patients with a preoperative haemoglobin level of less than 12 g/dl. A prospective audit was then performed over a nine month period, from 1st January to 30th September 2003, to assess the impact of these changes on our transfusion practice. Data was collected on 233 patients who had primary TKA performed during the period of our prospective audit. Patients were transfused if their blood loss exceeded a pre-calculated maximal allowable loss, or based on a 48 hour post-operative haemoglobin level. Seventeen of the 233 patients (7 %) received allogeneic blood. The average amount received was two units. Pre-operative anaemia and advanced patient age were predictive for increased risk of transfusion. Thirty six per cent of patients who were given a cell saver did not collect sufficient blood for re-transfusion. Ten per cent required further transfusion with allogeneic blood. There was no statistically significant difference in either the percentage of patients transfused or the volume of blood given to each patient between the two periods of audit. We did not find post-operative cell salvage to be an effective method of reducing allogeneic blood use.

Impaction allografting and the Kerboull acetabular reinforcement device: 35 hips followed for 3-7 years.

BACKGROUND: The incidence of acetabular loosening with segmental and cavitatory bone loss increases as the number of total hips implanted increases. Revision hip arthroplasty using impacted bone graft and an acetabular reinforcement device is one solution to this problem. PATIENTS AND METHODS: Clinically and radiographically, we assessed 35 hips in 33 patients who had undergone revision hip arthroplasty using impaction grafting and the Kerboull acetabular reinforcement device. Mean follow-up was 5 (3-7) years. RESULTS: The mean Mayo score preoperatively was 30, which improved to a mean score of 85. Good to excellent clinical results were seen in 25 patients. The 8 individuals scoring below 80 had significantly more co-morbid conditions than the others. No acetabular reconstruction required re-revision. Aseptic loosening occurred in 6 patients. Graft resorption occurred in 5 cases, resulting in inferior hook fracture of the Kerboull device. This was noted at a mean of 13 months after surgery. Further follow-up showed this to be non-progressive, with incorporation of the remaining graft to the host bone. These patients all had good to excellent Mayo hip scores. INTERPRETATION: Early results of revision acetabular surgery using impaction grafting and the Kerboull shell in patients with severe osteolysis have shown good functional outcome. However, 6 of 35 patients had radiographic evidence of aseptic loosening without progression for 4 years. Long-term follow-up is required to ensure that this loosening does not result in failure.

Fracture hematoma is a potent proinflammatory mediator of neutrophil function.

BACKGROUND: Patients with multiple skeletal injuries are susceptible to acute respiratory distress syndrome and multiple organ failure, which result from hyperactivation of the immune system. This study was designed to evaluate in vitro the proinflammatory properties of fracture hematoma (FH). METHODS: FH was isolated from patients undergoing emergent open reduction and internal fixation for isolated closed fractures. Neutrophils (PMNs), isolated from healthy volunteers, were exposed to the FH supernatant and activation was examined (CD11b and CD18 adhesion receptor expression and respiratory burst). PMN phagocytosis, apoptosis, and transmigration across an endothelial barrier were also assessed. RESULTS: FH increased PMN respiratory burst (control, 100; FH-treated, 186) and phagocytosis (control, 100; FH-treated, 172) but had no effect on adhesion receptor expression. Transendothelial migration of PMNs was unaffected, although FH was toxic to endothelial cells. In contrast, apoptosis of FH-treated PMNs was delayed (control, 46; FH-treated, 8). CONCLUSION: These effects, although beneficial at the site of injury in the context of antibactericidal function, may cause PMN-mediated tissue injury systemically.

Effects of systemic and regional taurine on skeletal muscle function following ischaemia-reperfusion injury.

INTRODUCTION: Tissues subjected to prolonged ischaemia are paradoxically further damaged when their perfusion is restored. The mechanisms underlying this ischaemia-reperfusion injury are complex, but oxidative attack is a central feature. Among the therapeutic agents used to attenuate ischaemia-reperfusion injury, endogenous agents such as taurine which form part of the native defence mechanism against oxidative damage are of particular interest. METHODS: Using a model of hindlimb ischaemia-reperfusion injury in the rat, taurine solution was administered either into the operated hindlimb, into the systemic circulation, or both. Contraction strengths of gastrocnemius biopsies from the operated and contralateral (control) hindlimbs of each animal were measured. RESULTS: Fast twitch strength was impaired significantly by ischaemia-reperfusion injury, and taurine injected into the operated limb conferred partial protection. A similar trend was observed for tetany, but protection by taurine was not statistically significant for tetanic contraction strength. CONCLUSION: Preservation of fast twitch strength following ischaemia-reperfusion injury by administration of taurine before ischaemia has clinical potential. However, delivery to the affected tissues during ischaemia presents technical difficulties.

Postoperative stiffness and adhesion formation around repaired and immobilized Achilles tenotomies are prevented using a model of heat shock protein induction.

BACKGROUND: Tendon repair and subsequent immobilization is frequently complicated by postoperative stiffness secondary to inflammation and peritendinous adhesions. Thermal preconditioning is known to reduce inflammation by inducing formation of cytoprotective heat shock proteins. This study evaluates the role of thermal preconditioning following complete division and repair of the Achilles tendon, with subsequent immobilization, mimicking the typical clinical scenario. MATERIALS AND METHODS: Twenty-four New Zealand White rabbits were used in the study. The treatment group underwent thermal preconditioning, by elevating their core temperature to 41.5 degrees C for 20 minutes. The Achilles tendon of the hindlimb was divided and repaired 18 hours following thermal preconditioning. The animals were sacrificed following 3 weeks of immobilization. Range of movement of the ankle, tendon gliding, quantity of adhesions, and weight of repaired tendons were assessed. RESULTS: Loss of range of movement at the ankle was significantly less in the treatment group versus controls (P = 0.02). The quantity of adhesions and weight of the repaired tendons were significantly reduced in the treatment group (P = <0.001 and P = 0.005, respectively). Tendon gliding relative to the surrounding soft tissue was also significantly improved in the treatment group (P = 0.002). CONCLUSION: Preconditioned animals demonstrated a significantly better range of ankle movement, decreases in adhesion formation and in the gliding, and dimensions of tendons. Thermal preconditioning therefore has the potential to improve clinical results in tendon surgery following repair and immobilization.

N-acetylcysteine attenuates lung injury in a rodent model of fracture.

BACKGROUND: Neutrophil-mediated lung injury is a cause of significant morbidity and mortality in patients with multiple injuries. We have shown previously that fracture hematoma can activate neutrophils and is thus a putative mediator of the systemic inflammatory response syndrome (SIRS), acute respiratory distress syndrome (ARDS) and multiple organ failure (MOF) in those patients with severe skeletal trauma. Our aim was to establish a rodent model of fracture which caused lung injury and subsequently to administer a drug following fracture to attenuate the lung injury. The drug we chose was N-acetylcysteine, a potent antioxidant. ANIMALS AND METHODS: Adult Sprague-Dawley rats were assigned to 4 groups: (1) general anesthetic only, (2) general anesthetic with bilateral femur fractures and nailing, (3) general anesthetic and N-acetylcysteine, (4) general anesthetic with bilateral femur fractures and nailing and N-acetylcysteine after the injury (n = 6 in each group). The dose of N-acetylcysteine was 0.5 mg/kg which was given intraperitoneally after injury to the treated groups. The rats were killed 24 hours after injury and some parameters of lung injury were evaluated--i.e., bronchoalveolar lavage (BAL), lung tissue myeloperoxidase levels (MPO) and wet/dry ratios of lung tissue. The results were analyzed, using one-way analysis of variance. RESULTS: Bilateral femur fracture produced a significant lung injury, measured by increases in MPO (25-43 microg/g tissue) and BAL protein (460-605 microg/mL). This effect was attenuated by treatment with N-acetylcysteine (MPO 43-9 microg/mL, BAL protein 605-198 microg/mL). INTERPRETATION: N-acetyl cysteine, if given after skeletal trauma, is of potential therapeutic benefit, in preventing SIRS, ARDS and MOF.

Relationship of the common peroneal nerve and its branches to the head and neck of the fibula.

The common peroneal nerve (CPN) lies on the neck of the fibula, which forms the floor of the so-called 'fibular tunnel.' The tunnel entrance is a musculo-aponeurotic arch derived from the soleus and peroneus longus muscles and it is here that the CPN is commonly compressed in cases of peroneal nerve palsy. This study aims to define the relationship of the CPN and its branches to the apex of the head of the fibula and to the tunnel, with special regard to possible sites of entrapment. The distances from the apex of the fibula to the opening of the fibular tunnel, the CPN bifurcation, and the exit point of the deep peroneal nerve (DPN) from the tunnel, were measured in 30 legs to ascertain possible sites of entrapment. The angle that the CPN subtended with the long axis of the fibula was measured to gauge the range of positions of the CPN at the neck of the fibula. An unyielding musculo-aponeurotic fibular arch at the entrance to the fibular tunnel was confirmed in all specimens. The DPN exited through a crescentic opening in the anterior intermuscular septum in all cases and no DPN branches were found in the lateral compartment in any specimen. The mean (+/-SD) distance from the apex of the head of the fibula to the opening of the fibular tunnel was 3.2 +/- 1.0 cm, to the CPN bifurcation was 3.8 +/- 0.9 cm, and to the DPN exit point was 7.0 +/- 1.5 cm. The mean angle subtended anteriorly from the long axis of the fibula by the CPN was 18.9 +/- 9.0 degrees. We recommend further study of the mean distances and reference angle in relation to fibular landmarks, for use in possible minimally invasive surgical procedures to decompress the fibular tunnel.

Suture-endobutton fixation of ankle tibio-fibular diastasis: a cadaver study.

Suture-Endobutton fixation is proposed as a minimally invasive, flexible fixation of ankle tibio-fibular diastasis, which would not require routine removal. This study tested the Suture-Endobutton construct in a cadaver syndesmosis injury model and compared this against A.O. syndesmosis screw fixation. Sixteen embalmed cadaver legs were used. Phase one consisted of placing the leg in a jig, generating an external rotation torque and measuring diastasis with increasing intraosseous membrane division. Phase two then compared the Suture-Endobutton construct vs. single four-cortex 4.5 mm A.O. screw fixation. Diastasis increased significantly with increasing intraosseous membrane division (p<0.001). No significant differences were seen in the mean rate of failure between the Suture-Endobutton and A.O. screw fixation. However, the Suture-Endobutton did give a significantly more consistent performance; the distribution of standard deviations for A.O. screw fixation was 0.64 mm higher than that for the Endobutton (95% C.I. 0.46 to 0.84). These results show that Suture-Endobutton fixation at least equals the performance of screw fixation and encourages clinical trials in ankle injuries with a syndesmosis diastasis.

Thermal preconditioning prevents peritendinous adhesions and inflammation.

Adhesion formation is one of the foremost obstacles to a reliably good outcome in tendon and joint surgery. Thermal preconditioning has been found to reduce the inflammatory response through the induction of molecular chaperone expression, a recently described family of cytoprotective intracellular proteins. The authors analyzed the effect of thermal preconditioning on the inflammatory response to surgery, on tendon healing, and on the formation of peritendinous adhesions in 16 New Zealand White rabbits. Very significant decreases in adhesion formation and in the gliding and dimensions of tendons in animals that had thermal preconditioning were found. Tendons from these animals also showed a decreased level of adhesion formation and a significantly diminished inflammatory response on histologic examination with no biomechanically significant deleterious effect on the strength of tendon healing on testing load to failure. These findings are consistent with induction of heat shock proteins by hyperthermic pretreatment. Such prevention of peritendinous adhesions and the inflammatory response to injury and surgery without compromising healing are findings that have significant implications for tendon surgery and all surgery involving joints and soft tissues.