Bennie Lindeque

Infection After Primary Total Hip Arthroplasty

The number of primary total hip arthroplasties (THAs) performed in the United States each year continues to climb, as does the incidence of infectious complications. The changing profile of antibiotic-resistant bacteria has made preventing and treating primary THA infections increasingly complex. The goal of this review was to summarize (1) the published data concerning the risk of surgical site infection (SSI) after primary THA by type of bacteria and (2) the effect of potentially modifying factors. The Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, Database of Abstracts of Reviews of Effects, EMBASE, Web of Science, and PubMed were searched. Studies dated between 2001 and 2011 examining primary THA in adults were included. Meta-analysis of the collected data was performed. The pooled SSI rate was 2.5% (95% confidence interval [Cl], 1.4%-4.4%; P<.001; n=28,883). The pooled deep prosthetic joint infection (PJI) rate was 0.9% (95% Cl, 0.4%-2.2%; P<.001; n=28,883). The pooled rate of methicillin-resistant Staphylococcus aureus SSI was 0.5% (95% Cl, 0.2%-1.5%; P<.001; n=26,703). This is approximately 20% of all SSI cases. The pooled rate of intraoperative bacterial wound contamination was 16.9% (95% Cl, 6.6%-36.8%; P=.003; n=2180). All these results had significant heterogeneity. The postoperative risk of SSI was significantly associated with intraoperative bacterial surgical wound contamination (pooled rate ratio, 2.5; 95% Cl, 1.4%-4.6%; P=.001; n=19,049).

Use of Carbon-Fiber-Reinforced Composite Implants in Orthopedic Surgery

Carbon-fiber-reinforced polyetheretherketone implants offer several benefits over traditional metal implants. Their radiolucent property permits improved, artifact-free radiographic imaging. Their lower modulus of elasticity better matches that of bone. Their fatigue strength is greater than most metal implants. This article reviews the use of these implants in orthopedic surgery, including treatment of conditions involving the spine, trauma, tumor, and infection.

Low-grade Cartilage Tumors: Diagnosis and Treatment

As a result of reading this article, physicians should be able to: 1. List the features that are useful in differentiating a low-grade chondrosarcoma from an enchondroma. 2. Describe the treatment principles of low-grade cartilage tumors based on the anatomic location and stage of the tumor. 3. Discuss the characteristics of a local recurrence after initial treatment and the general consequences.

Industry-driven Research: Have We Reached a Crisis Point?

We know that all academic and private units are cash strapped. Money for research is dwindling and it is diffi cult to obtain new funds. Big industry is reluctant to donate money for research for various reasons, and new rules from the Department of Justice make it diffi cult to donate money directly to a department. We therefore cannot blame big companies for pursuing their own research. For one, it is cheaper; they already have the facilities. Above all, they are able to direct the research to their liking, which of course is profi t driven. You cannot blame them. Unfortunately, this presents a big dilemma to the practicing medical fraternity. When is it ethical to use a new (in my mind, still experimental) prosthesis? Does the recent ASR metal-onmetal prosthesis recall from DePuy ring a bell? I have not seen any alerts put out by other companies also producing metal-onmetal prostheses. The British and Australian Hip Registries show a marked increase in revision rates of metal-on-metal cases as compared to cemented and noncemented cases. (By the way, both of these registries also show a higher revision rate for noncemented prostheses when compared to cemented hips.) If you are a private or academic orthopedic surgeon, you may get a visit from a local representative of a big company, almost always accompanied by an “expert” on a new operation or procedure. The expert representative is polished and presents his material in an overwhelmingly convincing way. Offered the advantage of being sent to a special course and inundated with educational material, you are psychologically compelled to jump on the bandwagon. I do not blame the orthopedic surgeon in practice. Percentage-wise, very few are trained in critically evaluating research protocols, publishing research, and joining a valid new development. The consequences are the possibility of a recall and of lawsuits, even against the surgeon. Why do huge, multinational companies risk losing hundreds of millions of dollars in class action lawsuits, or even risk going under? This has happened in the past and will probably happen in the future. The only answer is that the possibility of generating much higher profi ts in the future overrules reason and patient safety. It seems to me that in the absence of doctor-driven research, we should at least act as patient advocates as a corporate group. Remember, your name is also attached to disasters like these. No new prosthesis or procedure should be undertaken by a practicing orthopedic specialist unless it forms part of a national/worldwide controlled trial sanctioned by a panel of national/international experts and the local Institutional Review Board. What role should the American Academy of Orthopaedic Surgeons and overseas orthopedic associations play? They should publish guidelines for the orthopedic surgeon to adhere to before embarking on a new prosthesis or procedure. The whole scenario also rewrites the relationship between you and the service providers. They should understand that you are a patient safety advocate. They are primarily in the business of generating money, regardless of what they say. If we cannot marry those 2 driving forces, patient safety should prevail. It behooves us not to accept developer-published results but to look for independent researchers not driven by fi nancial gain. Dr Lindeque is from the Department of Orthopedics, University of Colorado-Denver, Aurora, Colorado. Dr Lindeque has no relevant fi nancial relationships to disclose. Correspondence should be addressed to: Bennie G.P. Lindeque, MD, Department of Orthopedics, Mail Stop F722, University of Colorado-Denver, 1635 N Aurora Ct, Aurora, CO 80045 (bennie.lindeque@ucdenver.edu). doi: 10.3928/01477447-20110526-01

A biomechanical comparison of three different lateral tibia locking plates.

The purpose of this study was to determine how well laterally placed modern tibia locking plates used in the treatment of Schatzker V tibial plateau fractures would uphold the medial plateau during axial loading. Fifteen third generation Sawbone tibias were obtained and an osteotomy was cut beneath the medial plateau to recreate Schatzker V type plateau fractures. Three groups were created (n=5 per group). Each group was plated with either a Synthes 4.5-mm LCP proximal tibial plate, a Zimmer NCB proximal tibia plate, or a DePuy Polyax tibial plate. A vertical load was applied over the medial plateau using an Instron servohydraulic test machine. Load measurements were analyzed at 2 and 3 mm of subsidence as well as load to failure. Failure was defined as closure of the wedge osteotomy or the medial condyle collapsing. A statistical difference was noted between the 2 plates from Synthes and DePuy and the plate from Zimmer with load carried at 2 and 3 mm of subsidence (Synthes 640.4 N & 943.7 N, Depuy 607.4 N & 891.0 N, Zimmer 459.7 N & 643.2 N). At failure, DePuy (2051.2 N) was statistically stronger than both Synthes (1724.8 N) and Zimmer (1724.8 N). The Synthes and DePuy plates both held up better than the Zimmer plate at 2 and 3 mm of subsidence. Despite this fact, all plates tested held up well above physiological forces of full and partial weight bearing and therefore would be appropriate for the treatment of Schatzker V type tibial plateau fractures.

Prevalence of methicillin-resistant Staphylococcus aureus among orthopedic patients at a large academic hospital.

Community-based methicillin-resistant Staphylococcus aureus (MRSA) contributes to postoperative surgical site infections, and it is therefore important to eliminate nasal carriage of MRSA before surgery. A total of 678 nasal swabs were performed on elective orthopedic patients undergoing surgery with the usage of metal implants. Thirty-eight specimens (5.6%) were positive for MRSA and 146 (21.5%) were positive for methicillin-sensitive S aureus (MSSA). A slow increase in the number of MSSA was noted between 2006 and 2007. Positive cases of MRSA nasal carriage were treated with nasal mupirocin ointment and chlorhexidine baths or showers for 5 days prior to surgery.

Biomechanical Assessment of Patellar Advancement Procedures for Patella Alta

Crouch gait deformity is common in children with cerebral palsy and often is associated with patella alta. Patellar tendon advancement typically is used to correct patella alta and restore normal knee mechanics. The purpose of this study was to determine the mechanical strength of surgical constructs used for fixation during patellar advancement procedures. This study used a cadaveric model to determine which of 3 surgical techniques is biomechanically optimal for patellar tendon advancement in treating patella alta. Twenty-four human cadaveric knees (8 per group) were prepared using 1 of 3 different common surgical techniques: tibial tubercle osteotomy, patellar tendon partial resection and repair at the distal patella, and patellar tendon imbrication. The patella was loaded from 25 to 250 N at 1 Hz for 1000 cycles. A significant difference in patella displacement under cyclical loading was found between surgical techniques. Tibial tubercle osteotomy exhibited significantly less displacement under cyclical loading than distal patella excision and repair (P<.0001) or imbrication (P=.0088). Imbrication exhibited significantly less displacement than distal patella excision and repair (P=.0006). Tibial tubercle osteotomy survived longest. Based on failure criteria of 5 mm of displacement, tibial tubercle osteotomy lasted between 250 and 500 cycles. The other 2 techniques failed by 25 cycles. This study offers quantitative evidence regarding the relative mechanical strength of each construct and may influence choice of surgical technique. [Orthopedics. 2016; 39(3):e492-e497.].

The Application of Cryoprobe Therapy in Orthopedic Oncology

The cryoprobe is a relatively new surgical tool offering a more selective destruction of unwanted cells. Using expanded versions of basic thermodynamic formulas of conduction and convection, mathematical models are becoming more effective at mapping out the zone of destruction that can be expected when using cryoprobes. The development of this technology will allow for better surgical planning and postoperative care to decrease patient morbidity and mortality. It is thought that this invaluable tool will become increasingly prevalent in orthopedics.

Unusual metastases from extremity soft tissue sarcomas.

The most common metastatic route for extremity soft-tissue sarcomas is via the venous system to the lungs. Metastases to other sites such as the brain, liver, and soft tissue distant from the primary tumor are rare. A tumor registry, prospectively kept since 1986, was reviewed for unusual metastatic spread. Of 3671 tumors, 346 high-grade extremity soft-tissue sarcomas were evaluated. A total of 15 patients (4.3%) presented with initial recurrence of disease that was extrapulmonary and distant from the site of the primary tumor. Four of these patients (27%) were successfully treated for their recurrence. Based on these findings, a different strategy for follow-up of patients after treatment of a high-grade extremity soft-tissue sarcoma is suggested.

Thermal Conductivity of Human Bone in Cryoprobe Freezing as Related to Density

Cryoprobes create localized cell destruction through freezing. Bone is resistant to temperature flow but is susceptible to freezing necrosis at warmer temperatures than tumor cells. Few studies have determined the thermal conductivity of human bone. No studies have examined conductivity as related to density. The study goal was to examine thermal conductivity in human bone while comparing differences between cancellous and cortical bone. An additional goal was to establish a relationship between bone density and thermal conductivity. Six knee joints from 5 cadavers were obtained. The epiphyseal region was sliced in half coronally prior to inserting an argon-circulating cryoprobe directed away from the joint line. Thermistor thermometers were placed perpendicularly at measured increments, and the freezing cycle was recorded until steady-state conditions were achieved. For 2 cortical samples, the probe was placed intramedullary in metaphyseal samples and measurements were performed radially from the central axis of each sample. Conductivity was calculated using Fourniers Law and then plotted against measured density of each sample. Across samples, density of cancellous bone ranged from 0.86 to 1.38 g/mL and average thermal conductivity ranged between 0.404 and 0.55 W/mK. Comparatively, cortical bone had a density of 1.70 to 1.86 g/mL and thermal conductivity of 0.0742 to 0.109 W/mK. A strong 2-degree polynomial correlation was seen (R2=0.8226, P<.001). Bone is highly resistant to temperature flow. This resistance varies and inversely correlates strongly with density. This information is clinically relevant to maximize tumor ablation while minimizing morbidity through unnecessary bone loss and damage to surrounding structures. [Orthopedics. 2017; 40(2):90-94.].