Sumon Nandi

Adverse Tissue Reactions in Modular Exchangeable Neck Implants: A Report of Two Cases

Dual-modular femoral stems with exchangeable necks theoretically allow optimization of hip joint biomechanics via selective restoration of femoral anteversion, offset, and limb length. A potential disadvantage is the possible generation of metal ions and debris by fretting and crevice corrosion at the additional stem-neck interface. We present 2 cases of early-onset adverse inflammatory tissue reactions as a result of accelerated corrosion at the stem-neck interface of a dual-modular implant, requiring subsequent revision of well-fixed components.

Corrosion and Adverse Local Tissue Reaction in One Type of Modular Neck Stem

Modular neck stems allow for optimization of joint biomechanics by restoring anteversion, offset, and limb length. A potential disadvantage is the generation of metal ions from fretting and crevice corrosion. We identified 118 total hip arthroplasty implanted with one type of dual-modular femoral component. Thirty-six required revision due to adverse local tissue reaction. Multivariate analysis isolated females and low offset necks as risk factors for failure. Kaplan-Meir analysis revealed small stem sizes failed at a higher rate during early follow-up period. Although the cobalt/chrome levels were higher in the failed group, these tests had low diagnostic accuracy for ALTR, while MRI scan was more sensitive. We conclude that the complications related to the use of dual modular stems of this design outweigh the potential benefits.

Pharmacologic Risk Factors for Post-Operative Delirium in Total Joint Arthroplasty Patients: A Case–Control Study

Total joint arthroplasty (TJA) patients are at increased risk of post-operative delirium (POD) given their demographics and functional impairment. Certain pharmacologic agents are known to cause delirium, but those that cause delirium following TJA are unknown. Our aim was to explore if specific anesthetic agents, opiate pain medications, or benzodiazepines are associated with POD following TJA. A matched case (n=98)-control (n=365) design and conditional logistic regression model were used to examine risk factors for POD among TJA patients at our institution from 2006 to 2010. The model was adjusted for gender, pre-operative alcohol use, and pre-operative depression. Our data suggest that isoflurane and benzodiazepines are associated with an increased risk of delirium in TJA patients and should be used with caution. Hydromorphone and morphine did not increase the risk of delirium in TJA patients and may be considered for post-operative pain control.

Diagnosis and treatment of intraoperative popliteus tendon impingement.

Herein, we describe a simple, effective strategy for diagnosing and treating intraoperative popliteus tendon impingement during total knee arthroplasty (TKA). When lateral impingement is detected intraoperatively during TKA, manual isolation of the popliteus tendon can help determine the cause. Using this technique, the etiology of intraoperative lateral impingement during TKA was never misdiagnosed and the popliteus tendon was never unnecessarily released. The technique described allows for accurate diagnosis of intraoperative lateral impingement during TKA and the prevention of unnecessary popliteus resection.

Neurovascular Structure Proximity to Acetabular Retractors in Total Hip Arthroplasty

Neurovascular injury during total hip arthroplasty (THA) may result in considerable morbidity or mortality. The most common cause of intraoperative neurovascular injury during THA is retractor compression. Our aims were to: 1) determine proximity of common acetabular retractor positions during THA to adjacent neurovascular structures; and 2) determine effect of patient gender on these measurements. Retractor to neurovascular structure distances were measured on 32 preoperative computed tomography images and 16 cadavers. Our data suggest the anterior inferior iliac spine is the safest anterior acetabular retractor position. With inferior progression along the anterior wall, the distance to the femoral neurovascular bundle decreases. Due to its proximity to the sciatic nerve, the position of the posterior retractor should be monitored during acetabular preparation, particularly in women.

Head-Neck Taper Corrosion following Total Hip Arthroplasty with Stryker Meridian Stem:

Background Taper corrosion at the modular junctions of total hip arthroplasty (THA) femoral stems are known to cause locally destructive adverse local tissue reaction (ALTR). However, the implants at risk remain to be fully elucidated. Case review We report the case of a 76-year-old woman with hip pain, abductor weakness, and sciatic nerve symptoms 2 years following metal-on-polyethylene THA. Serum cobalt levels were elevated, while chromium levels were normal. Magnetic resonance imaging demonstrated ALTR. The patients symptoms resolved following head and liner exchange with ceramic head and titanium sleeve. Literature review Previous studies have reported ALTR secondary to head-neck taper corrosion in cobalt chrome alloy and titanium alloy stems used in metal-on-polyethylene (MoP) THA. The stems described above span 4 manufacturers with varying taper geometries. To our knowledge, this is the first report of ALTR due to head-neck taper corrosion in a Stryker Meridian titanium-molybdenum-zirconium-iron (TMZF) alloy stem. Clinical relevance Close surveillance for ALTR may be considered in patients with this prosthesis. Further investigation of the TMZF alloy and V40 taper geometry of this stem may guide future implant design.

Choosing a Femoral Head: A Survey Study of Academic Adult Reconstructive Surgeons

BACKGROUND Our aim was to examine how academic adult reconstructive surgeons have interpreted evidence on femoral head material in total hip arthroplasty (THA). METHODS A 16-question survey to evaluate attitudes toward ceramic and cobalt-chrome head use was emailed to 274 faculty at 42 US adult reconstruction fellowship programs. RESULTS With 116 respondents, the response rate was 42.2%. Faculty use ceramic heads 72.9% of the time. The most common reason why respondents do not use ceramic heads is cost (44.8%). Ninety-four percent of faculty have observed head-neck taper corrosion in cobalt-chrome on polyethylene THA, while 9.5% of faculty have observed head-neck taper corrosion in ceramic on polyethylene THA. Only 6.0% of surgeons have seen Biolox Delta ceramic fracture. CONCLUSION Adult reconstruction thought leaders are guided by evidence suggesting that with ceramic heads, taper corrosion and fracture are rare. Cost and personal experience also strongly influence their implant selection. Efforts to equalize cost of ceramic and cobalt-chrome heads may free surgeons to practice in a purely evidence-based fashion.

Comparative survival analysis of porous tantalum and porous titanium acetabular components in total hip arthroplasty

Background Porous tantalum acetabular components (PoTa) are well-studied, but less is known about widely used porous titanium (PoTi) acetabular components. We performed a comparative survival analysis between PoTi and PoTa acetabular components. Methods Primary or revision THA performed using PoTi (n = 2,976) or PoTa (n = 184) acetabular components with minimum 2-year follow-up (PoTi n = 1,539; PoTa n = 157) were analysed. Univariate and multivariate logistic regression were performed to test the effect of porous metal acetabular component type on revision surgery for aseptic cup loosening. Multivariate model was adjusted for acetabular defect severity according to the Paprosky Classification. Results Only PoTi components used in revision THA failed. Survival of the PoTi acetabular component was 98.6% when used in revision THA at mean 48.3-month follow-up. After adjusting for severity of acetabular defect, there was no difference in survival between PoTi and PoTa acetabular components when used in primary or revision THA. Conclusions After adjusting for acetabular defect severity, both PoTa and PoTi acetabular components had excellent survival at mean 44.4-month (range 4.3-91.5 months) follow-up when used in primary and revision THA.

CORR Insights®: Periprosthetic Joint Infection in Hip Arthroplasty: Is There an Association Between Infection and Bearing Surface Type?

I nfection following THA commonly results in reoperation, may result in mortality, and is costly to the healthcare system. The risk of periprosthetic joint infection (PJI) may be decreased by identifying and modifying its predictors. Recently, THA bearing surface has been identified as a potential predictor of PJI. More specifically, previously published studies [3, 6] have found metal-on-metal (MoM) bearings to have a higher risk of PJI than ceramic-on-ceramic (CoC) bearings [1, 2]. Recent work has not found any difference in the rate of PJI between CoC and ceramic-on-polyethylene (CoP) or metal-on-polyethylene (MoP) THA. The study by Pitto and Sedel examined the role of THA bearing surface as it relates to the risk of PJI using data from the New Zealand National Joint Registry during a 15year period. The authors found that CoC THA had a lower risk of PJI than CoP, MoP, and MoM bearings, which were equivalent in PJI risk. Where Do We Need To Go?

2015@@@A Low-Cost Digital Templating System for Total Hip Arthroplasty@@@42: 46

Acetate templating for total hip arthroplasty (THA) is cumbersome and inaccurate. High cost hampers mainstream use of digital templating despite ease of use and accuracy. The aim of this study was to validate a low-cost digital THA templating system. Low-cost digital templating software was created using C# programming language. On the basis of power calculations, three surgeons templated 20 consecutive anteroposterior pelvis X-rays using this software against an industry standard. Intraclass correlation coefficient for both systems was approximately .90 for component size and femoral neck cut position. Bland-Altman plots demonstrated that both systems predicted actual implant size with similar accuracy. Interrater reliability was not significantly different between the two systems. This low-cost digital THA templating system is up to 12-fold lower in cost than currently available software with similar accuracy.