Growth of an intrapelvic pseudotumor associated with a metal-on-metal total hip arthroplasty after revision arthroplasty causing a femoral nerve neuropathy

The development of pseudotumors is not uncommon with metal-on-metal total hip arthroplasty. Pseudotumors that dissect into the retroperitoneal space can cause symptoms of nerve compression. We describe a case of a 53-year-old male with a metal-on-metal total hip arthroplasty who developed mild symptoms of a femoral nerve neuropathy 6 years postoperatively. Revision arthroplasty to a ceramic-on-polyethylene articulation and debridement of the pseudotumor was performed. Postoperatively, the patient's femoral neuropathy progressed and a repeat magnetic resonance imaging showed an increase in size of the pseudotumor despite the removal of the offending metal-on-metal articulation. The patient subsequently underwent a laparoscopic excision of the retroperitoneal pseudotumor. By 17 months post laparoscopic excision of the pseudotumor, the patient's motor deficits resolved, however, sensory deficits persisted in the anteromedial thigh.

Are metal ion levels a useful trigger for surgical intervention?

The purpose of this study was to determine if cobalt and chromium ion levels can predict soft tissue damage at total hip revision. This study included 90 metal-on-metal total hip patients with preoperative cobalt and chromium ion levels. Tissue damage noted at revision surgery was graded on a 4-point scale. Sensitivity, specificity, and predictive values were calculated for various threshold values. Receiver operating characteristic analysis was conducted. Using 7 ppb as a threshold, cobalt and chromium ion levels had poor sensitivity and specificity (Co, 65% and 56%; Cr, 29% and 75%). Positive predictive values for cobalt and chromium were only 48% and 26% respectively. The area under the curve was 0.37 for cobalt and 0.44 for chromium. The length of time to revision significantly correlated with tissue damage (P = .001). Ion levels are unreliable predictors of periarticular soft tissue damage and should not be used in isolation as surgical intervention triggers.

Venous thromboembolism following major orthopedic surgery: what is the risk after discharge?

Guidelines recommend thromboprophylaxis for at least 10 days to prevent venous thromboembolism in patients undergoing high-risk orthopedic surgery, such as total hip arthroplasty (THA) or total knee arthroplasty (TKA). Furthermore, the recently updated ACCP guidelines also recommend extending the duration of thromboprophylaxis for 28 to 35 days following THA or hip fracture surgery as the risk for venous thromboembolism persists for up to 3 months after surgery. Extended-duration thromboprophylaxis (up to 6 weeks) with low-molecular-weight heparin is significantly more effective in preventing venous thromboembolism in orthopedic surgery patients than the recommended practice of at least 10 days. Extended-duration thromboprophylaxis may require risk stratification to identify high-risk patients. Current risk-assessment models have limitations and are not specific to orthopedic surgery patients; therefore, improvements may facilitate the use of extended-duration thromboprophylaxis in high-risk patients, thereby reducing the burden of venous thromboembolism.

Femoral version: definition, diagnosis, and intraoperative correction with modular femoral components

Normal femoral version contributes to the inherent stability of the hip joint. Abnormal version is found in a variety of hip diseases afflicting children and adults. At the time of reconstruction for end-stage hip disease, maintaining proper femoral version in conjunction with acetabular version allows for hip stability and unimpeded functional range of motion. In those instances where femoral version is significantly abnormal, a means of correction at time of surgery is necessary. Non-modular femoral components allow for minor adjustments in version at time of surgery. To accommodate significant versional abnormalities, the modular S-ROM (DePuy Orthopaedics Inc, Warsaw, Ind) was introduced in 1984. In a series of 156 primary S-ROM total hip arthroplasties, the ability to correct for abnormal version resulted in excellent clinical results with no incidence of hip instability and excellent range of motion.

Effects of sterilization on the Tekscan digital pressure sensor

Investigations into the effects of sterilization on a new biomechanical pressure sensor are necessary before contemplating in vivo use. Ten, designated Experimental, "K-Scan" digital pressure sensor arrays were sterilized with ethylene oxide gas (EtO), and their ability to accurately and reproducibly measure an applied load of 2225 N (500 lb) was assessed. Simultaneously, 10 un-sterilized sensor arrays, designated Control, were assessed. Each array was loaded 10 times inside a two-dimensional curved surface, and all arrays exhibited high reproducibility (coefficients of variation<2.0%). Following sterilization, the Experimental sensors showed a 22.2% average decrease in recorded force, a statistically significant difference from the pre-sterile data (p<0.002). However, when the Experimental sensors were re-calibrated post-sterilization, they showed only a 0.1% average decrease in recorded force, not a statistically significant difference (p>0.05, beta<0.05). Following 1-week storage, trial 2 data of the Control sensors showed a less dramatic yet significant 3.4% average decrease in recorded force when compared to trial 1 data (p<0.02). Control trial 2, once re-calibrated, showed a 0.5% average decrease in recorded force, not a statistically significant difference (p>0.05, beta<0.05). Results suggest that, following EtO sterilization, accurate and reproducible pressure measurements can be obtained from K-Scan sensors when calibration is performed at time of use.

Early failure of a proximally cemented, distally uncemented total hip arthroplasty

This investigation prospectively studied a consecutive series of 22 proximally cemented, distal cementless, femoral components with a minimum follow-up time of 24 months. The prosthesis was a titanium, proximally cemented, femoral component with a distal press-fit fluted design. Five hips (23%) developed aseptic mechanical loosening at an average of 46.2 months and required revision. The technique required excessive removal of cancellous bone leading to a suboptimal bone-cement interface. The early failure rates of this prosthesis are unacceptably high for a contemporary hip design. To the best of our knowledge, no clinical studies have reported on the stability and longevity of this new proximal cementing technique incorporated with a distal press-fit femoral design.

The use of a Bayesian forecasting model in the management of warfarin therapy after total hip arthroplasty

This study was performed to compare the computer-based and physician-based management of warfarin therapy after total hip arthroplasty (THA). The computer-assisted and control groups of patients were placed on warfarin postoperatively and followed for a 1-month period. A significant difference (P<.05) was found between the mean number of days needed to reach therapeutic anticoagulation in the control group (4.7+/-3.0 days) and the experimental group (2.8+/-1.4 days) and the proportion of patients in each group who were discharged with a subtherapeutic international normalized ratio (INR) (INR <1.5). The computer-based management of warfarin therapy was more efficient than unaided physician-based management and therefore may lead to improved, cost-effective patient care by reducing length of hospital stay and complications attributable to nontherapeutic anticoagulation in THA patients.

The influence of oral anticoagulation therapy on deep vein thrombosis rates four weeks after total hip replacement

PURPOSE

The purpose of this study was to assess the rate of postoperative deep vein thrombosis (DVT) as a function of oral anticoagulation therapy after total hip replacement surgery.

METHODS

A total of 125 patients completed the study. All the patients received sequential gradient pneumatic compression over elastic stockings until hospital discharge. In addition, all the patients underwent postoperative heparin therapy followed by oral warfarin therapy, adjusted in dose to maintain a goal international normalized ratio (INR) level of 2.0 to 3.0. Warfarin therapy and compression stockings were continued for 1 month after surgery. Bilateral duplex scanning was performed 1 and 4 weeks after surgery to assess the rate of DVT.

RESULTS

Nineteen of the 125 patients had DVT develop (15.2%). Of those thromboses, six (31.6%) and 13 (68%) were detected 1 week and 1 month after surgery, respectively. The rate of proximal DVT was 2.4% (3 of 125) 1 week after surgery and rose to 8.2% (10 of 122) 1 month after surgery. Most DVT cases (64%; 12 of 19) were asymptomatic. The patients in whom DVT developed had significantly lower INR values during the second to fourth postoperative weeks than did those patients without thrombosis, and no differences in INR values were found during the first postoperative week.

CONCLUSION

The risk of the development of DVT extends beyond hospital discharge in patients who undergo total hip replacement, despite a regimen of prolonged oral anticoagulation therapy. This is particularly true in patients whose INR values did not reach therapeutic range during the first postoperative month. Therefore, thrombosis prophylaxis regimens on the basis of the administration of warfarin should try to maintain INR values within therapeutic range during the entire first postoperative month to minimize the incidence of DVT.

Recognition of lumbar disc disease with magnetic resonance imaging

Ten normal adult volunteers, 75 patients with low back pain and/or lumbar radiculopathy, 16 patients following chymopapain treatment, 14 patients with recurrent symptoms following disc surgery, and two patients with distal cord compression were scanned on Fonar 3000 permanent magnet scanner. Of all the patients 98 had additional computed tomography scans (CT) of the lumbar spine and 82 had myelography. Lumbar magnetic resonance imaging (MRI) and CT scans were both diagnostic in cases of herniated and extruded discs. MRI scan showed more information concerning the degenerative state of the intervertebral discs. It was relatively more accurate in detecting, small bulging and herniated discs without ruptured anulus and the relation of the migrated fragments of extruded discs to both the back of the vertebrae and the thecal sac. Moreover, lumbar MRI matched the clinical response of disc disease to chymopapain treatment more than lumbar CT scan. In addition, the MRI studies differentiated more accurately postoperative epidural fibrotic changes from recurrent herniated and/or extruded disc and detected distal spinal cord abnormalities. CT scan easily detected laterally herniated lumbar discs. Myelography was the diagnostic study in cases of arachnoiditis.

Rational approach to the differentiation of vascular and neurogenic claudication

Lower extremity pain caused by exercise but relieved by rest is usually a reliable symptom of chronic arterial insufficiency. However, similar discomfort often occurs in patients with neurospinal compression. Furthermore, arterial occlusive disease and demonstrable spinal stenosis may be present simultaneously. Fifty-two patients with symptoms suggesting intermittent claudication comprised the study group. All were proven to have a nonarterial cause of their complaint. The study consists of a retrospective analysis of the diagnostic methods used in confirming the proper diagnosis. Conclusions reached suggest a rational approach to solution of individual patient problems. The nonvascular origin of the symptoms was suggested initially by clinical evaluation in 19 patients, and by noninvasive arterial evaluation in an additional 22. The neurospinal origin of symptoms was obscured in 11 patients because of the presence of significant arterial occlusive disease, as demonstrated by nominvasive arterial testing. Seven of the 11 patients underwent arterial reconstruction, which failed to relieve their symptoms. Subsequently, the neurospinal origin of these symptoms was proven by appropriate treatment. This experience has shown that the errors in diagnosis and treatment could have been avoided by using a combined diagnostic approach, correlating results of an accurate clinical evaluation with noninvasive arterial testing as well as the findings shown on lumbosacral spine films.

Alpha1-antitrypsin deficiency with severe panniculitis. Report of two cases

Two patients with profound decrease of alpha1-antitrypsin (PiZZ) presented with severe pannicultis (Weber-Christian disease); one had systemic panniculitis including pancreatitis. Another possible case is quoted from the literature. Although milder forms of panniculitis can have normal Pi phenotypes and alpha1-antitrypsin levels, the marked reduction of antiproteolytic activity found in PiZZ homozygotes may predispose to or aggravate the lesions of Weber-Christian disease.