Steven F. Harwin

INFLUENCE OF INTRAMEDULLARY VERSUS EXTRAMEDULLARY ALIGNMENT GUIDES ON FINAL TOTAL KNEE ARTHROPLASTY COMPONENT POSITION : A RADIOGRAPHIC ANALYSIS

A prospective study of 116 consecutive Kinemax cemented posterior cruciate ligament-retaining total knee arthroplasties was carried out. Similar surgical technique was used with a single variable: 61 were implanted using intramedullary guides on the tibia and 55 were implanted using extramedullary guides on the tibia. A radiographic study was performed after at least 1 year of follow-up to evaluate postoperative component position and compare the difference in the accuracy of positioning of the femoral and tibial components. Radiographic analysis showed that satisfactory position was achieved using both types of instrumentation. No statistically significant difference was observed in either the coronal or sagittal plane of the femoral component and the sagittal plane positioning of the tibial component. However, the coronal plane positioning of the tibial component revealed a statistically significant difference (P < .01), with intramedullary guides being superior to extramedullary guides. Also observed, was that using either technique, patients with less accurate postoperative positioning tended to be obese, with wide intramedullary canals. Patients with significant extraarticular deformities, marked bowing, and those with prior surgery or fractures may not be suitable for intramedullary guides, and they may require the use of extramedullary guides and intraoperative radiographic control. The ideal indication for the use of intramedullary instrumentation is in the patient who is not obese, with no extraarticular deformity, and with a well-defined, but not excessively wide, tibial medullary canal. Since tibial component malalignment in general, and coronal plane malalignment in particular, may adversely affect the long-term survival of total knee arthroplasties, the use of intramedullary alignment instrumentation is recommended when possible.

Patellofemoral Complications in Symmetrical Total Knee Arthroplasty

A review of 356 Kinemax (Howmedica, Inc, Rutherford, NJ) cemented posterior cruciate ligament-retaining condylar total knee arthroplasties employing a symmetrical femoral component articulating with a medially offset symmetrical dome patella component was carried out to examine the results and determine the incidence and nature of the patellofemoral complications. Follow-up was from 3 to 8 years, with a mean of 5.1 years. A review of patellofemoral complications in previously reported homogeneous series of symmetrical and asymmetrical implants is presented. Mean postoperative Knee Society scores improved to 91, function scores to 86, and Hospital of Special Surgery scores to 90 yielding 95% good and excellent results. Mean postoperative range of motion was -1.5 degrees extension to 113 degrees flexion. There were five patellofemoral complications (1.4%), including two symptomatic subluxations, two distal pole avulsion fractures, and one lateral facet fracture. There were two reoperations necessary for patellofemoral problems (0.56%), one to correct subluxation and one for excision of the fractured lateral facet. These rates are lower than those previously reported for asymmetrical implants as well as current and phased-out symmetrical designs of total knee arthroplasty in the intermediate term. This review suggests that cemented total knee arthroplasty with symmetrical patellofemoral resurfacing with an offset patella dome and posterior cruciate ligament retention yields low patellofemoral complications and reoperations. The symmetrical femoral component appears to be a satisfactory compromise of normal femoral anatomy, which decreases inventory and cost without adversely affecting patellofemoral function and complications.

The effects of obesity and morbid obesity on outcomes in TKA.

The negative effects of obesity following total joint arthroplasty, such as increased morbidity and mortality, have been well documented in literature. However, little is known about whether specific body mass indices can be used as cutoffs to determine which patients are most at risk for having a poor postoperative outcome. We evaluated the effects of differing levels of obesity as measured by body mass index (BMI) on implant survivorship, Knee Society scores, complications, and radiographic outcomes. A systematic review of the literature was performed to identify all studies reporting outcomes of total knee arthroplasty in obese (30 ≤ BMI < 40 kg/m2) and morbidly obese patients (40 ≤ BMI < 50 kg/m2). Twenty-four studies were identified in our literature search. At a mean 5-year follow-up, morbidly obese patients (88%) had significantly lower implant survivorship than obese patients (95%) and nonobese patients (97%). Significantly, lower postoperative mean Knee Society objective and function scores (71 and 60 points) were observed for morbidly obese patients than for nonobese patients (75 and 90 points), but obese patients did not have significantly lower Knee Society objective and function scores than nonobese patients (78 and 84 points). Complication rates for nonobese, obese, and morbidly obese patients were 9, 15, and 22%, respectively, all of which were significantly different. However, no significant difference was observed in the incidence of radiolucent lines that were 12, 19, and 14%, respectively. Thus, we conclude that a BMI greater than 40 kg/m2 may be used as a cutoff to help guide patient education and treatment options for primary total knee arthroplasty.

Immunohistochemical analysis of mechanoreceptors in the human posterior cruciate ligament

Although long-term studies report successful results with total knee arthroplasty (TKA), performed with or without posterior cruciate ligament (PCL) retention, controversy exists as to which is preferable in regard to patient outcome and satisfaction. The possible proprioceptive role of the PCL may account for a more normal feeling of the arthroplasty. Although the PCL has been examined using various histological techniques, immunohistochemical techniques are the most sensitive for neural elements. Therefore an immunohistochemical study was designed to determine the patterns of innervation, the morphological types of the proprioceptors, and their immunohistochemical profile. During TKA, samples were obtained from 22 osteoarthritic PCLs and subjected to immunohistochemical analysis with mouse monoclonal antibodies against neurofilament protein (NFP), S100 protein (S100P), epithelial membrane antigen (EMA), and vimentin (all present in neuromechanoreceptors). Three normal PCLs from cadaveric specimens were also obtained and analyzed for comparison. Five types of sensory corpuscles were observed in both the normal and the arthritic PCLs: simple lamellar, Pacini-like, Ruffini, Krause-like, and morphologically unclassified. Their structure included a central axon, inner core, and capsule in lamellar and Pacini corpuscles and variable intracorpuscular axons and periaxonal cells in the Ruffini and Krause-like corpuscles. The immunohistochemical profile showed the central axon to have NFP immunoreactivity, periaxonal cells to have S100P and vimentin immunoreactivity, and the capsule to have EMA and vimentin immunoreactivity. Nerve fibers and free nerve endings displayed NFP and S100P immunoreactivity. The immunohistochemical profile of the PCL sensory corpuscles is almost identical to that of cutaneous sensory corpuscles. Some prior histological studies of the PCL reported Golgi-like mechanoreceptors, and others found encapsulated corpuscles but no Golgi-like structures. This report determined the innervation of the PCL by the more sensitive immunohistochemical means, revealing four major types of encapsulated mechanoreceptors. The plentiful and varied types of encapsulated mechanoreceptors found in even the arthritic PCL suggests a rich proprioceptive role. It is controversial as to whether preservation of the PCL at TKA improves postoperative proprioception. Our findings tend to support those clinical reports of improved proprioception after PCL-retaining versus PCL-substituting TKAs. The presence of many and varied types of mechanoreceptors may account for the improved stair climbing reported in patients with PCL-retaining TKA and may contribute to patient satisfaction and a more normal feeling after TKA.

Long-Term Implant Survivorship of Cementless Total Knee Arthroplasty: A Systematic Review of the Literature and Meta-Analysis

Cementless total knee arthroplasty (TKA) has had limited use in the United States, however, recent reports have demonstrated promising results, but there has been no meta-analysis to examine these outcomes in the past 5 years. In this review, 37 studies (2,940 patients and 3,568 TKAs) were identified and used, comparing cementless to cemented TKA. Pooled implant survivorship was compared using a fixed-effect meta-analysis between cementless and cemented TKA, and between cementless TKA with and without screw fixation. Cementless TKA had implant survivorship comparable to cemented TKA (odds ratio, 1.1; 95% confidence interval [CI], 0.62-2.00). The mean survivorship at 10 years for cementless TKA was 95.6% compared with 95.3% for cemented TKA. At 20-year follow-up, implant survivorship decreased to 76 and 71%, respectively. No difference was observed between fixation with or without screws (OR, 1.1; 95% CI, 0.16-7.5). Implant survivorship for cementless TKA was comparable to the current gold standard cemented TKAs.

Long-term outcomes of MUA for stiffness in primary TKA.

Knee stiffness following primary total knee arthroplasty (TKA) is a well-recognized problem which leads to poor patient outcomes and may limit patient activities of daily living. Manipulation under anesthesia (MUA) is one option for the treatment of knee stiffness. However, there has been controversy regarding the safety and long-term efficacy of this procedure. A systematic review of the literature was performed to identify studies that reported the clinical outcomes and measured range of motion for patients undergoing MUA. Fourteen studies (913 patients) reported range of motion results following MUA at up to 10-year follow-up. The mean premanipulation and final range of motion were 66 and 99 degrees, respectively. Compared with preoperative range of motion, the gain in the range-of-motion arc at 1-, 5-, and 10-year follow-up was 30, 33, and 33 degrees, respectively. Complications were rare with only two reported periprosthetic fractures, resulting in an incidence of 0.2%. MUA for a stiff primary TKA is an efficacious procedure to restore range of motion. Early gains in motion appear to be maintained at long term, and in some cases patients may gradually improve further at mid-term follow-up. The risk of periprosthetic fracture is low, making MUA a safe option for improving knee range of motion.

Postoperative blood loss prevention in total knee arthroplasty.

Blood loss is a serious concern during lower extremity total joint arthroplasty with the estimated reduction in hemoglobin concentration known to vary between 2 and 4 g/dL after total knee arthroplasty (TKA). Allogeneic transfusions are commonly used to treat the acute blood loss and postoperative anemia to diminish the potential cardiovascular risks in up to 50% of such cases with a high volume of blood loss. However, these transfusions are associated with the risks of immunologic reactions, immunosuppression, and infection transmission. Multiple blood-saving strategies have been developed to minimize blood loss, to reduce transfusion rates, to decrease complications, and to improve outcomes in the postoperative period. Currently, there are no clear guidelines on the blood management strategies adopted to lessen the blood loss associated with TKA. The aim of this study was to review the literature and provide a broad summary of the efficacy and complications associated with several blood-saving measures that are currently used in the postoperative period. Evidence suggests that simple techniques such as limb elevation, cryotherapy, compression dressings, and drain clamping may reduce external drainage, however, whether these techniques lead to less allogeneic transfusions is currently debatable. Further research on using a combination of these strategies and their cost-effectiveness are needed.

Bicruciate-retaining total knee arthroplasty: a review.

Total knee arthroplasty (TKA) has been shown to have excellent long-term outcomes and survivorship in numerous studies, however, with changes in patient demographics, questions have arisen about the use of conventional arthroplasties and their functionality in highly active, young patients. The recent interest in bicruciate-retaining prostheses is aimed to address the need for an implant that can mimic a natural knee during high activity levels. Although there are currently few of these prostheses which are being utilized, results from prior studies have demonstrated similar results to that of anterior cruciate ligament-sacrificing TKA in terms of function and survivorship. In this review, we will describe the history, kinematics, clinical outcomes, concerns, and future outlook of bicruciate-retaining arthroplasty.

Preoperative Blood Management Strategies for Total Knee Arthroplasty

Elective total knee arthroplasty is frequently associated with considerable blood loss and a concomitant decline in hemoglobin postoperatively. This often leads to high rates of allogeneic transfusions, with reports of up to 69%, to treat postoperative anemia. Allogeneic blood transfusions have been shown to be an independent risk factor for increased adverse outcomes, such as prolonged length of hospital stay and postoperative infections. Although multiple preoperative blood management strategies have been proposed, there are no concise guidelines, as few studies have compared the relative efficacy of these techniques. The aim of this review was to evaluate current evidence on the various preoperative blood management strategies for patients undergoing total knee arthroplasty and to provide an overview of the safety and efficacy of these practices. Specifically, we evaluated preoperative autologous blood donation, iron therapy, and intravenous erythropoietin. Current evidence suggests that these techniques independently may be effective at reducing the incidence of allogeneic blood transfusions, correcting preoperative, and preventing postoperative anemia. However, more studies are necessary to evaluate combination protocols, as well as the cost-effectiveness and safety of these practices as part of routine preoperative blood management for total knee arthroplasty.

Critical review of minimally invasive approaches in knee arthroplasty.

Despite high survivorship for total knee arthroplasty, many reports have described low patient-satisfaction rates. Standard parapatellar approaches have been linked with decreased quadriceps muscle strength, which may in turn lead to prolonged rehabilitation and altered kinematics. Although technically demanding, minimally invasive techniques offer the potential for shorter recovery times and improved strength. Our purpose was to compare perioperative factors, the clinical and radiographic outcomes, complications, and survivorship of several minimally invasive approaches to each other and to the conventional medial parapatellar approach. A total of 23 level I or II studies were reviewed. There were no statistically significant differences in perioperative factors, clinical or radiographic outcomes, survivorship, or complication rates between patients the various minimally invasive approaches to a standard approach. The only significant difference observed was in recovery of quadriceps muscle function (shorter in patients who had a minimally invasive approach). The minimally invasive lateral approach had more complications than the other minimally invasive approaches. The mini-midvastus approach had the best clinical outcomes at 1 and 3 months when compared with other minimally invasive approaches and standard approaches. The mini-subvastus approach had the lowest rate of complications, overall. Further multicenter randomized trials are needed to determine the minimally invasive approach that best improves outcomes while minimizing complications.