Strong association between smoking and the risk of revision in a cohort study of patients with metal‐on‐metal total hip arthroplasty

Thus far the ability to predict who will develop early failure following the insertion of a metal‐on‐metal (MoM) bearing has been very limited. Our objective was to assess the effect of smoking on failure rates in patients with MoM bearing, compared with patients with ceramic‐on‐polyethylene (CoP) bearing. From a prospective hospital‐based registry we included all primary THAs operated upon between 1/2001 and 12/2011 with MoM or CoP bearings of the same cup design and head size (28 mm). We compared revision rates through 10/2013 classified by smoking status and type of bearing. We included 1,964 patients (median age 71, 57% women), 663 with MoM and 1,301 with CoP bearing. Mean follow‐up was 6.9 years (range 1.8–12.8). Revisions were required for 56 THAs. In patients with MoM bearing the adjusted incidence rate of revision among ever‐smokers was four times greater than among never‐smokers (95% CI 1.4–10.9). Among those with CoP bearing, the rate ratio was only 1.3 (95% CI 0.6–2.5). We found a strong association between smoking and increased failure of MoM THAs. In contrast, the association was weak for patients with CoP bearing. Smoking might be a trigger or an effect amplifier for adverse reactions to metal debris from MoM bearings. © 2014 The Authors. Journal of Orthopaedic Research Published by Wiley Periodicals, Inc. J Orthop Res 32:762–768, 2014.     

An evaluation of prophylactic treatments to prevent post traumatic joint stiffness

Arthrofibrosis is a major obstacle to restoring joint function after trauma. The objective of this study was to evaluate montelukast, forskolin, and triamcinolone as possible means of prophylaxis against the formation of arthrofibrosis. Forty‐eight rats underwent surgical knee trauma with post‐operative immobilization in full flexion. The treatment groups were: control (CTL), oral montelukast (3.75 mg/kg/day) (MLK), intra‐articular forskolin injections (0.6 mg/kg) (FSK), and intra‐articular triamcinolone injections (0.68 mg/kg) (STR). Rats were sacrificed after 14 days and femorotibial contracture angles were measured with the posterior capsule intact and with the posterior capsule cut. A 0.015Nm extension moment was applied to the knee. All treatment groups had significant reductions in contracture angle compared to the control. Mean contractures with the posterior capsule intact were 32°(CTL), 20° (MLK), 22° (FSK), and 7° (STR). Contractures with the posterior capsule cut were 28° (CTL), 19° (MLK), 20° (FSK), and 5° (STR). The STR group was significantly better than FSK and MLK. Triamcinolone injections provided dramatic reductions in stiffness. Both forskolin and montelukast provided significant, though lesser, reductions in stiffness. While the triamcinolone contracture angles were significantly better, the novel treatments of forskolin and montelukast provided encouraging results and should be studied further. © 2014 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 32:1520–1524, 2014.     

Improved Radiographic Outcomes With Patient-Specific Total Knee Arthroplasty

Patient-specific guides can improve limb alignment and implant positioning in total knee arthroplasty, although not all studies have supported this benefit. We compared the radiographs of 100 consecutively-performed patient-specific total knees to a similar group that was implanted with conventional instruments instead. The patient-specific group showed more accurate reproduction of the theoretically ideal mechanical axis, with fewer outliers, but implant positioning was comparable between groups. Our odds ratio comparison showed that the patient-specific group was 1.8 times more likely to be within the desired + 3° from the neutral mechanical axis when compared to the standard control group. Our data suggest that reliable reproduction of the limb mechanical axis may accrue from patient-specific guides in total knee arthroplasty when compared to standard, intramedullary instrumentation.     

Incidence of Patellar Clunk Syndrome in Fixed Versus High-Flex Mobile Bearing Posterior-Stabilized Total Knee Arthroplasty

The geometry of the intercondylar box plays a significant role in the development of patellar clunk syndrome. We reviewed the incidence of patella clunk at mid-to-long-term follow-up of a rotating high-flex versus fixed bearing posterior stabilized TKA design. 188-mobile and 223-fixed bearing TKAs were reviewed for complications, incidence of patellar clunk, treatment, recurrence rates, range of motion, and patient satisfaction. Patellar clunk developed in 22 knees in the mobile (11.7%) and in 4 (1.8%) in the fixed bearing group (P < 0.001). 23 out of 26 cases resolved with a single arthroscopic treatment and 2 resolved with a second procedure. The mean postoperative range of motion was 122.4°. All but one patient reported overall satisfaction with the index procedure. In contrast with other recent studies we found a significant incidence of patellar clunk in high-flex mobile bearings. Despite the high rate of patellar clunk syndrome, overall patients did well and were satisfied with their outcomes.     

Current Data Do Not Support Routine Use of Patient-Specific Instrumentation in Total Knee Arthroplasty

The purpose of this systematic review and meta-analysis is to compare patient-specific instrumentation (PSI) versus standard instrumentation for total knee arthroplasty (TKA) with regard to coronal and sagittal alignment, operative time, intraoperative blood loss, and cost. A systematic query in search of relevant studies was performed, and the data published in these studies were extracted and aggregated. In regard to coronal alignment, PSI demonstrated improved accuracy in femorotibial angle (FTA) (P = 0.0003), while standard instrumentation demonstrated improved accuracy in hip-knee-ankle angle (HKA) (P = 0.02). Importantly, there were no differences between treatment groups in the percentages of FTA or HKA outliers (>3 degrees from target alignment) (P = 0.7). Sagittal alignment, operative time, intraoperative blood loss, and cost were also similar between groups (P > 0.1 for all comparisons).     

Morbidity and Mortality in the Thirty-Day Period Following Total Hip Arthroplasty: Risk Factors and Incidence

The study sought to ascertain the incidence rates and risk factors for 30-day post-operative complications after primary total hip arthroplasty (THA). Complications were categorized as systemic or local and subcategorized as major or minor. There were 17,640 individuals who received primary THA identified from the 2006-2011 ACS NSQIP. The mortality rate was 0.35% and complications occurred in 4.9%. Age groups ≥ 80 years (P <0.001) and 70-79 years old (P = 0.003), and renal insufficiency (P = 0.02) best predicted mortality. Age ≥80 years (P <0.001) and cardiac disease (P = 0.01) were the strongest predictors of developing any postoperative complication. Morbid obesity (P <0.001) and operative time > 141 minutes (P <0.001) were strongly associated with the development of major local complications.     

Influence of Clinical and Radiological Variables on the Extent and Distribution of Periprosthetic Osteolysis in Total Hip Arthroplasty with a Hydroxyapatite-Coated Multiple-Hole Acetabular Component: A Magnetic Resonance Imaging Study

Polyethylene wear-induced osteolysis constitutes the most severe long-term complication of total hip arthroplasties (THA). Our aim was to assess through MRI the severity and growth pattern of osteolysis, as well as the influence clinical-radiographic variables exert. We analyzed 75 THA with an average evolution time of 13.67 years. The implant was a titanium alloy, non-cemented, multiple-hole model with hydroxyapatite coating. Osteolysis was found with a peripheral pattern in 48 and a central pattern in 6; in 52 cases it was continuous, and in 4, isolated. Out of 118 screws, 20 exhibited lysis. There was a proportional correlation between osteolysis severity and wear rate with age, physical activity and acetabular abduction, as well as an association between said variables and peripheral and continuous patterns.     

Radiological imaging in the knee

The knee joint is particularly vulnerable to injury or damage as it supports the full weight of the body. Thus, conditions affecting the knee can be debilitating. History, clinical examination, laboratory investigations and radiological findings help complete the picture and establish a definite diagnosis. The choice of the appropriate imaging method depends on the differential diagnosis, availability and urgency of a radiological investigation. It is also important to consider how the imaging findings will affect prognosis and management. In the review that follows an overview of the most common knee pathologies alongside the most significant findings in various imaging modalities is provided.