[The influence of reduced bone density on primary stability of cementless femoral stems. A biomechanical in vitro study]. / Der Einfluss der Knochendichte auf die Primärstabilität von zementfreien Femurschaftprothesen--Eine biomechanische In-vitro-Studie.

OBJECTIVE: The aim of the present in vitro study is to examine the influence of bone density on the primary stability of cementless femoral stems in nine pairs of human cadaveric femurs. METHOD: The human proximal femurs were evaluated with regard to their bone density by dual-energy X-ray absorptiometry. Two pairs of human cadaveric femurs had an osteoporotic and two pairs an osteopenic bone stock. After implantation of the cementless femoral stems, the prostheses were loaded in a physiological position. Subsidence, rotation and interface motion of the stems were measured with load cycles up to 2000 Newton. RESULTS: There was no significant correlation between the bone density of the proximal femur and the primary stability of the femoral stem in subsidence (p=0.23) and rotation (p=0.79). Reduced bone density in the osteoporotic and osteopenic human femora did not increase the interface motion at the proximal or distal part of the prosthesis (p>0.05). CONCLUSION: The initial stability of cementless femoral stems was not influenced by the bone density, at least in this biomechanical in vitro study. Thus, theoretical conditions exist that allow secondary osseointegration of femoral stems also in cases of reduced bone density.

Interleukin-6, procalcitonin and TNF-alpha: markers of peri-prosthetic infection following total joint replacement.

This prospective study evaluates the role of new laboratory markers in the diagnosis of deep implant infection in 78 patients (41 men and 37 women) with a revision total knee or hip replacement. The mean age at the time of operation was 64.0 years (19 to 90). Intra-operative cultures showed that 21 patients had a septic and 57 an aseptic total joint replacement. The white blood cell count, the erythrocyte sedimentation rate and levels of C-reactive protein, interleukin-6, procalcitonin and tumour necrosis factor (TNF)-alpha were measured in blood samples before operation. The diagnostic cut-off values were determined by Received Operating Characteristic curve analysis. C-reactive protein (> 3.2 md/dl) and interleukin-6 (> 12 pg/ml) have the highest sensitivity (0.95). Interleukin-6 is less specific than C-reactive protein (0.87 vs 0.96). Combining C-reactive protein and interleukin-6 identifies all patients with deep infection of the implant. Procalcitonin (> 0.3 ng/ml) and TNF-alpha (> 40 ng/ml) are very specific (0.98 vs 0.94) but have a low sensitivity (0.33 vs 0.43). The combination of C-reactive protein and interleukin-6 measurement provide excellent screening tests for infection of a deep implant. A highly specific marker such as procalcitonin and pre-operative aspiration of the joint might be useful in identifying patients with true positive C-reactive protein and/or interleukin-6 levels.

[Minimally invasive treatment of osteoid osteoma with CT-guided radiofrequency ablation in long-term follow-up]. / Die minimalinvasive Therapie beim Osteoidosteom mittels CT-gesteuerter Thermokoagulation im Langzeitverlauf.

AIM: We treated 74 patients with symptomatic osteoid osteoma by CT-guided radiofrequency ablation (CT-RF) and investigated the rate of success and complications. PATIENTS AND METHODS: 74 patients were treated by CT-RF between March 1997 and August 2001. The nidus was first located by thin-cut CT sections and then penetrated by a 2 mm coaxial drill or an 11-gauge Jamshidi needle followed by insertion of the RF probe and heat application for a period of 4-6 minutes at 90 degrees C. We investigated the recurrence of pain, complications, hospital stay, duration of postoperative pain and function. RESULTS: Nine recurrences occurred after the initial procedure, and one after a second CT-RF (rate of primary success 87.8 %, rate of secondary success 88.8 %; 98.6 % success rate in all). There was one minor complication in one case. CONCLUSIONS: CT-guided RF ablation cured 73 of 74 patients (98.6 %). It is a safe, simple, cost effective and minimally invasive treatment, which has stood the test of a long-term follow-up and we suggest it to be the treatment of choice in most cases.

[Long-term influence of the spongiosa metal surface prosthesis on the periprosthetic bone. A radiological and osteodensitometric analysis of implantation of the S& G (ESKA) hip prosthesis]. / Langfristiger Einfluss der anatomisch angepassten spongiösen Endoprothese auf den periprothetischen Knochen.

INTRODUCTION: The anatomically shaped, cementless total hip replacement (THR) (S and G, ESKA Lübeck) has a fully porous coating for secondary osseointegration. The aim of the present study was to analyse the long-term effect of the prosthesis on periprosthetic bone remodelling. METHODS: 137 THR in 117 patients were analysed clinically and radiographically 12.8 years (10-14.9 years) postoperatively. The average age at the last follow-up was 71.8 years (range: 34-87 years). Osteodensitometric DEXA measurements of the periprosthetic bone in comparison to the contralateral non-operated femora were performed. RESULTS: Cumulative survival rates of all implanted THR (n = 231) at 14.9 years were 86.2 % (+/-5.3 %) for the fully porous coated stem and 90.1 % (+/- 8 %) for the cup. Five stem fractures (3.6 %) at the middle part were recorded. The Harris hip score of the non-revised THR at the last follow-up averaged 88.3 (34-100) points. Bony atrophy in the proximal periprosthetic femora in Gruen zones I (16.8 %) and VII (34.6 %) confirmed a proximal stress-shielding. Osteodensitometric analyses demonstrated in comparison to the contralateral femora (BMD 1.3 g/cm (2)) a significantly reduced bone density at the calcar femoris (BMD 0.9 g/cm (2)) (p < 0.001). CONCLUSION: The original goal of a physiological load transfer has not been realised with this fully porous, cementless THR. The anatomic S & G stem will mainly be osseointegrated by distal load transfer.

Long-term results of the metal-cancellous cementless Lübeck total hip arthroplasty: a critical review at 12.8 years.

INTRODUCTION: The influence of a spongy metal surface total hip arthroplasty (THA) (S&G, ESKA, Lübeck, Germany) on the clinical, psychometric, and radiograhic long-term results were examined. MATERIAL AND METHODS: An amount of 137 THA with the cementless spongy metal Lübeck hip prosthesis were evaluated long-term, radiographically and clinically, with a mean follow-up time of 12.8 years (range 10.1-14.9 years). The MOS SF-36 was used to assess the health-related quality of life (HRQL). RESULTS: Cumulative survival rates were 90% (+/-8%) for the cups and 86% (+/-5%) for the stems at 14.9 years. Four stems fractured at the middle part (3%) without major trauma. In the remaining patients the clinical results expressed as Harris Hip Score (HHS) averaged 88 (range 34-100). Patients above 60 years undergoing THA had no significant difference in HRQL (MOS SF-36) in comparison to the age-matched healthy population (P>0.05). Patients younger than 60 years had scores lower than normal in the physical function domains (P<0.01), but were comparable in the mental health domains (P>0.05). Radiolucent lines and bone atrophy related to stress shielding by distal fixation were found in the periprosthetic Gruen Zone I (19.8, 16.8%) and VII (10.3, 27.1%) of the proximal femur. DISCUSSION: Whereas the rate of aseptic cup failures of the cementless spongy metal Lübeck hip prosthesis is among the best, the failure rate of the stems is attributable to osteolysis of the proximal femur. The fractures of the stem may be attributed to the combination of the lack of proximal support, the fully porous stem made of a cast cobalt-chrome-molybdenum alloy, and the narrow dimension of the stem core. The long-term results of the spongy metal cup are good, whereas the high loosening and fracture rate of fully coated stem are a source of concern especially with regard to the difficult revision scenario with frequent massive bone loss.

Acute compartment syndrome following intramedullary pulse lavage and débridement for osteomyelitis of the tibia.

The implantation of gentamicin loaded polymethylmethacrylate (PMMA) beats and other local antibiotic carriers is a common practice in the treatment of chronic osteomyelitis as is the use of local jet lavage débridement. This article presents the case of a patient with chronic osteomyelitis of the tibia, who had no complication after débridement, intramedullary reaming and pulse lavage without tourniquet but sustained a compartment syndrome 2 weeks later during a second procedure in which an intraoperative tourniquet and pulse lavage were combined.

Surgical treatment of symptomatic osteochondroma. A three- to eight-year follow-up study.

Our aim was to investigate the outcome of excision ofosteochondromas. Between 1994 and 1998, 92 symptomatic osteochondromas in 86 patients were excised. There were 40 women and 46 men with a mean age of 20 years (3 to 62). Of these, 56 had a solitary osteochondroma and 30 had multiple hereditary tumours. The presenting symptoms were pain (79.1%), swelling (23.3%), reduced range of movement (19.8%), cosmetic abnormalities (17.4%), and bursitis (12.8%). The most common site (37.6%) was around the knee. Four patients had major complications (4.7%) including one intra-operative fracture of the femoral neck and three nerve palsies which resolved after decompression. Six patients had minor complications. Overall, 93.4% of the preoperative symptoms resolved after excision of the tumours. Excision is a successful form of treatment for symptomatic osteochondromas with a low morbidity.

Nonpharmacologic thromboembolic prophylaxis in total knee arthroplasty.

Deep venous thrombosis is the most common complication in patients having elective total knee replacement. Pneumatic compression devices play an important role in the prophylaxis of deep venous thrombosis and effectively decrease the risk of distal deep venous thrombosis. The combination therapy with pharmacologic agents has the benefit of decreasing the rate of proximal deep venous thrombosis and therefore is recommended. In the absence of clinical data, recent in vivo flow studies suggest that calf or combined foot and calf compression are superior to foot compression alone. Epidural anesthesia in comparison with general anesthesia decreases the incidence of thromboembolic disease after total knee arthroplasty. Although hypotensive anesthesia and intraoperative heparin have been proven to substantially lower the incidence of deep venous thrombosis after total hip arthroplasty, the current literature does not support its application during the implantation of a total knee replacement. Pneumatic compression devices are an important part of deep venous thrombosis prophylaxis especially in the early postoperative period considering that pharmacologic anticoagulation is contraindicated in the first 12 hours after spinal anesthesia and in the presence of an epidural line.

Cyclooxygenase-2 inhibitor for pain management in osteoid osteoma.

Thirteen patients with osteoid osteoma were enrolled in a prospective trial to test whether rofecoxib, a selective cyclooxygenase-2 inhibitor, is as effective for pain control as acetylsalicylic acid. Each patient documented the pain level using a visual analog scale, with 0 being no pain and 10 being unbearable pain, during 2 days of no pain medication, 4 days of 500 mg acetylsalicylic acid three times a day, and 10 days of 25 mg rofecoxib once a day. Oral administration of 500 mg acetylsalicylic acid three times a day led to a significant decrease in pain at night, pain at rest, and pain induced by exercise. Twenty-five milligrams rofecoxib given once a day at midday showed the same remarkable improvement in pain at night, pain at rest, and pain induced by exercise. Rofecoxib in comparison with acetylsalicylic acid showed a trend toward lower pain levels in all categories. Rofecoxib offered a significantly better reduction in pain at rest during the day than did acetylsalicylic acid. Results of the current study suggest that pain induction in osteoid osteoma is related to cyclooxygenase-2, an enzyme that is blocked by acetylsalicylic acid and rofecoxib. Conservative medical treatment with rofecoxib for osteoid osteoma is recommended when percutaneous intervention is associated with significant morbidity.

[Prevention of thrombosis in hip prosthesis implantation]. / Thromboseprophylaxe in der Hüftendoprothetik.

Deep venous thrombosis is one of the most common perioperative complications after total hip arthroplasty. Systemic anticoagulation has been the gold standard for prophylaxis of postoperative deep venous thrombosis. There is no doubt that early mobilization and the use of pneumatic compression devices decrease the overall deep venous thrombosis rate. Single postoperative prophylaxis may decrease the overall deep venous thrombosis rate to 15-20% and the proximal deep venous thrombosis rate to approximately 7%. However,the activation of thrombogenesis is mainly an intraoperative event. The position of the extremity during the implantation of the femoral component leads to obstruction of the venous outflow. At the same time, the coagulation cascade is activated and markers of thrombogenesis in the blood are increased. By combining intraoperative (hypotensive epidural anesthesia and intraoperative heparin) and postoperative (pneumatic compression devices and aspirin) prophylaxis of deep venous thrombosis, the total deep venous thrombosis rate is reduced to less than 10% and the proximal deep venous thrombosis rate is reduced to 2%. Patients with increased risk for deep venous thrombosis should receive Coumadin or low-molecular weight heparin. In addition, hypotensive epidural anesthesia reduces the intraoperative blood loss and the need for postoperative blood transfusion.

Osteoarticular allograft in surgery for high-grade malignant tumours of bone.

We assessed the results of 17 limb-salvage procedures using osteoarticular allografts after wide resection of high-grade malignant bone tumours. All patients received chemotherapy. At the five-year follow-up, three patients had died from metastases. The allografts survived for five years in only seven patients all of whom had good function, ranging from 73% to 90% of normal. The allografts were removed because of fracture in seven patients and infection in one, and in all of these a second limb-salvage procedure was undertaken. With such a low rate of survival of osteoarticular allografts, we believe that their use in the management of high-grade malignant bone tumours should, at best, be considered a temporary solution.