Goal Of Total Knee Arthroplasty Research Articles

The “midsulcus line” as a landmark for tibial resection during total knee arthroplasty

BackgroundProper tibial alignment is an important goal of total knee arthroplasty. Most surgeons agree that tibial coronal alignment should be within three degrees of neutral mechanical alignment. The “midsulcus line” is a line drawn along the sulcus of the tibial spines, and then the line is continued in the sagittal plane and extended onto the anterior tibia where it intersects the tibial tubercle approximately 3 to 4mm lateral to the tubercle's medial border. The tibial cut was then made perpendicular to this line. The aim of our study was to assess, using CT scans, whether this line provided a consistent guide for planning the tibial cut in total knee arthroplasty. MethodsWe reviewed the CT scans of the knees of 107 patients with osteoarthritis who had undergone a CT scan for planning of custom cutting guides. The midsulcus line was drawn on all scans. ResultsWe found that in 105 of 107 knees, a perpendicular cut to this tibial landmark would have delivered a cut surface within three degrees of neutral mechanical alignment. ConclusionsThe midsulcus line is a reliable landmark for planning the tibial resection in total knee arthroplasty. Level of EvidenceIII

The posterior-stabilized knee—No post required

The goal of total knee arthroplasty is to provide the patient with a stable, painless knee. The modern total joint orthopedist has many options to help achieve stability through cruciate-retaining and posterior-stabilized implants. Over the lifespan of the implant eventual posterior cruciate ligament instability can make an otherwise well-functioning cruciate-retaining implant fail. The drawback of many posterior-stabilized implants include the need for more bone resection and the noisy clunk of the polyethylene post contacting the femoral component. The use of an ultracongruent polyethylene liner is an effective way to achieve stability with a cruciate sacrificing method.

Kinematic analysis of a posterior-stabilized knee prosthesis.

Background:The goal of total knee arthroplasty (TKA) is to restore knee kinematics. Knee prosthesis design plays a very important role in successful restoration. Here, kinematics models of normal and prosthetic knees were created and validated using previously published data.Methods:Computed tomography and magnetic resonance imaging scans of a healthy, anticorrosive female cadaver were used to establish a model of the entire lower limbs, including the femur, tibia, patella, fibula, distal femur cartilage, and medial and lateral menisci, as well as the anterior cruciate, posterior cruciate, medial collateral, and lateral collateral ligaments. The data from the three-dimensional models of the normal knee joint and a posterior-stabilized (PS) knee prosthesis were imported into finite element analysis software to create the final kinematic model of the TKA prosthesis, which was then validated by comparison with a previous study. The displacement of the medial/lateral femur and the internal rotation angle of the tibia were analyzed during 0–135° flexion.Results:Both the output data trends and the measured values derived from the normal knee's kinematics model were very close to the results reported in a previous in vivo study, suggesting that this model can be used for further analyses. The PS knee prosthesis underwent an abnormal forward displacement compared with the normal knee and has insufficient, or insufficiently aggressive, “rollback” compared with the lateral femur of the normal knee. In addition, a certain degree of reverse rotation occurs during flexion of the PS knee prosthesis.Conclusions:There were still several differences between the kinematics of the PS knee prosthesis and a normal knee, suggesting room for improving the design of the PS knee prosthesis. The abnormal kinematics during early flexion shows that the design of the articular surface played a vital role in improving the kinematics of the PS knee prosthesis.

Gap Balancing vs. Measured Resection Technique in Total Knee Arthroplasty

A goal of total knee arthroplasty is to obtain symmetric and balanced flexion and extension gaps. Controversy exists regarding the best surgical technique to utilize to obtain gap balance. Some favor the use of a measured resection technique in which bone landmarks, such as the transepicondylar, the anterior-posterior, or the posterior condylar axes are used to determine proper femoral component rotation and subsequent gap balance. Others favor a gap balancing technique in which the femoral component is positioned parallel to the resected proximal tibia with each collateral ligament equally tensioned to obtain a rectangular flexion gap. Two scientific studies have been performed comparing the two surgical techniques. The first utilized computer navigation and demonstrated a balanced and rectangular flexion gap was obtained much more frequently with use of a gap balanced technique. The second utilized in vivo video fluoroscopy and demonstrated a much high incidence of femoral condylar lift-off (instability) when a measured resection technique was used. In summary, the authors believe gap balancing techniques provide superior gap balance and function following total knee arthroplasty.

(i) Planning and consent for primary total knee replacement

The aim of primary total knee replacement is to decrease pain, restore function and reduce disability. This is achieved by correct patient selection and adequate planning so that the appropriate prosthesis can be implanted in the appropriate manner. The technical goal of total knee arthroplasty is to implant a well-aligned prosthesis in a well-balanced knee, with linear patellar tracking and achieve infection-free healing. Weight bearing anteroposterior, lateral and patellofemoral joint radiographs are mandatory and standing long leg views help determine alignment. CT and MRI scans may be of value in assessing bone stock and ligamentous deficiency. If there is a lack of bone stock a stemmed prosthesis or augmentation wedges may be required, whilst a ligamentous deficiency may necessitate a stabilized or constrained prosthesis. The consent process for TKR commences at the outpatient consultation and must consider the reason for operation, alternative treatments, all common and serious risks and the rehabilitation protocol. There is an increasing use of multimedia tools (e.g. www.orthoconsent.com) in the consent process.

The use of navigation to achieve soft tissue balance in total knee arthroplasty — A randomised clinical study

BackgroundAchieving soft tissue balance is an operative goal in total knee arthroplasty. This randomised, prospective study compared computer navigation to conventional techniques in achieving soft tissue balance. MethodsForty one consecutive knee arthroplasties were randomised to either a non-navigated or navigated group. In the non-navigated group, balancing was carried out using surgeon judgement. In the navigated group, balancing was carried out using navigation software. In both groups, the navigation software was used as a measuring tool. ResultsBalancing of the mediolateral extension gap was superior in the navigation group (p=0.001). No significant difference was found between the two groups in balancing the mediolateral flexion gap or in achieving equal flexion and extension gaps. ConclusionsComputer navigation offered little advantage over experienced surgeon judgement in achieving soft tissue balance in knee replacement. However, the method employed in the navigated group did provide a reproducible and objective assessment of flexion and extension gaps and may therefore benefit surgeons in training. Level of evidenceLevel I, RCT.

Severe Persistent Synovitis After Cobalt-chromium Total Knee Arthroplasty Requiring Revision

Implant-related hypersensitivity is a well-established cause of failure after total hip arthroplasty but is a rare complication after total knee arthroplasty (TKA). It remains a relatively unpredictable and poorly understood cause of implant-related failure. This article describes 5 patients (6 knees) who presented with persistent pain and hypertrophic synovitis after TKA using a cobalt-chromium component. Extensive perioperative workup, including white blood cell count, erythrocyte sedimentation rate, C-reactive protein, joint aspiration, and intraoperative cultures, ruled out infection as a cause of the symptoms. All knees demonstrated appropriate ligamentous balance and were well aligned, with all components noted to be well fixed at revision. In all patients, the clinical condition improved dramatically after revision to zirconium femoral and titanium metal-backed tibial components. Pain and functional outcome scores improved in all patients. Intraoperative histopathology revealed a thickened synovium with either a predominantly lymphocytic or histiocytic monocellular response. Final pathology confirmed that no infection was present in any patient. The goal of TKA is to produce a well-performing, pain-free joint. When patients present with recurrent pain and synovitis after TKA, infection must be excluded. When infection and instability have been excluded, metal hypersensitivity should be considered as a cause of primary TKA failure. In these patients, revision to a zirconium femoral component can provide predictable and effective clinical improvement.

Alignment Changes Due to Incomplete Component Seating in Total Knee Arthroplasty

Mechanical axis restoration remains a primary goal of total knee arthroplasty. Incomplete asymmetrical component seating, through intended or unintended alterations in surgical technique, changes the component alignment and, thus, the overall mechanical axis. Using a trigonometric analysis, it was determined that incomplete seating of 1 to 5 mm can alter the coronal alignment by 0.7° to 4.9°, depending on the amount of asymmetry as well as the size of the femoral or tibial component. This analysis quantifies the degree of changes surgeons should expect when incomplete component seating is encountered intraoperatively.

Difference in Stair Negotiation Ability Based on TKA Surgical Approach

Several surgical approaches for total knee arthroplasty (TKA) have been developed to minimize soft-tissue trauma and expedite functional recovery. A group of 61 subjects undergoing computer-navigated, minimally invasive TKA were randomized to receive a mini-parapatellar, standard parapatellar, mini-midvastus (MV), or mini-subvastus approach. Before and after treatment, subjects were asked to negotiate stairs in a self-selected manner. This study used the manner of stair negotiation (i.e., use of handrail, step-over-step, step-by-step) as a proxy for functional ability. Subjects who received TKA through a mini-MV approach demonstrated a significantly lower level of function at 2 and 4 months. If early functional recovery is a goal of TKA, surgeons should be cautious when considering the mini-MV approach, which was found to be inferior to other approaches in this study.

Range of Motion of Standard and High-Flexion Posterior Cruciate-Retaining Total Knee Prostheses*

The main goals of total knee arthroplasty are pain relief and improvement in function and the range of motion. The purpose of this study was to compare the ranges of motion of the knees of patients treated with a standard posterior cruciate-retaining total knee prosthesis in one knee and a high-flexion posterior cruciate-retaining total knee prosthesis in the other. Fifty-four patients (mean age, 69.7 years) received a standard posterior cruciate-retaining total knee prosthesis in one knee and a high-flexion posterior cruciate-retaining total knee prosthesis in the contralateral knee. Five patients were men, and forty-nine were women. At a mean of three years postoperatively, the patients were assessed clinically and radiographically with the knee-rating systems of the Knee Society and the Hospital for Special Surgery and with the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score. The mean postoperative Knee Society and Hospital for Special Surgery knee scores were 93.7 and 89 points, respectively, for the knees with a standard posterior cruciate-retaining prosthesis, and they were 93.9 and 90 points, respectively, for the knees with a high-flexion posterior cruciate-retaining prosthesis. The mean postoperative WOMAC score was 22 points. Postoperatively, the mean ranges of motion without and with weight-bearing were 131 degrees (range, 90 degrees to 150 degrees) and 115 degrees (range, 75 degrees to 145 degrees), respectively, in the knees with a standard prosthesis and 133 degrees (range, 90 degrees to 150 degrees) and 118 degrees (range, 75 degrees to 145 degrees), respectively, in those with a high-flexion prosthesis. Patient satisfaction and radiographic results were similar in the two groups. No knee had aseptic loosening, revision, or osteolysis. After a minimum duration of follow-up of three years, we found no significant differences between the two groups with regard to the range of knee motion or the clinical or radiographic parameters.

COMPARISON OF HIGH FLEXION DESIGN AND POSTERIOR STABILIZATION PROSTHESES OF TOTAL KNEE ARTHROPLASTY BY GAIT ANALYSIS

Introduction: The primary goal of total knee arthroplasty (TKA) is to resolve knee destruction and associated problems at the end stages of diseases such as osteoarthritis and rheumatoid arthritis. High satisfactory rate has been reported in terms of pain relief and correction of deformity. However, the method for objective assessment of the outcome, such as range of motion (ROM) and quantitative evaluation of the clinical outcome of TKA, is to be confirmed. The purpose of this study was mandatory to investigate the ROM objectively and the newly designed prostheses. Materials and methods: The study was done in randomly selected patients who received dynamic measurement of knee function. Twenty-six patients participated in the study. They were divided into two groups (13 patients in A and 13 patients in B group), according to the knee prostheses they had received. Basic knee functions were evaluated in various dynamic activities, including nonweight bearing status of knee flexion, level walking, kneeling, and squatting, using computerized gait analysis techniques (Vicon 512 system). Passive knee ROM and static alignment were measured using traditional goniometer. HSS scores, physical, and neural examination were recorded. Results: After comparing patients in almost similar criteria, results have shown that there was no significant difference between two types of knee prostheses in randomly selective patients. Conclusion: Newly designed prostheses for achieving higher flexion angle cannot guarantee to provide better knee flexion for every patient. A patient, who can achieve higher knee flexion in pre-operative status, will have high flexion results in post-operative result. In other words, poor knee flexion function in pre-operation will lead to poor knee flexion function in post-operation status. Minor prosthesis design has little to do with the surgical outcome of knee flexion.

Rapid Recovery Protocols and Minimally Invasive Surgery Help Achieve High Knee Flexion

Although the primary goal of total knee arthroplasty is to relieve pain, the attainment of high flexion has emerged as an important secondary goal. Clinical pathways are evolving and focus on rapid recovery. The entire perioperative process for the patient and family, including office and hospital procedures, has been streamlined and patients are advised from the initial evaluation they will be able to quickly return to activities of daily living. Currently, patients are out of bed within hours of surgery, engaging in activities that require a substantial range of motion in the treated knee. They are frequently discharged directly to home within 24 to 48 hours. We retrospectively reviewed two groups of patients undergoing primary total knee arthroplasty whose perioperative management differed only by surgical approach, namely, standard versus less invasive. Refined perioperative protocols in combination with a less invasive, mini-arthrotomy approach using special instrumentation resulted in earlier discharge to home, higher range of motion and improved clinical and pain scores.

Load balance in total knee arthroplasty: an in vitro analysis

One of the goals of total knee arthroplasty (TKA) is to balance the loads between the compartments of the knee. An instrumented load cell that measures compartment loads in real time is utilized to evaluate conventional, qualitative methods of achieving this balance. TKA was performed on 10 cadaveric knees. Prior to and after load balancing, compartment forces were measured at flexion angles of 0-90 degrees. Knees were randomly assigned into one of two groups, based upon whether or not the surgeons could visualize the load cell's output during balancing. Prior to attempting load balance, there were significant differences between the medial and lateral compartment loads for all knees (p < 0.05). After attempting balance with the aid of the load cell, there was equal load balance at all angles studied. Without the aid of the load cell, balance was not consistently achieved at every angle. Conventional load balancing techniques in TKA are not perfect.

Interdisciplinary Management for Total Knee Replacement in Patients with Hemophilia and Severe Arthropathy.

Severe hemophilia is complicated by spontaneous joint bleedings, leading to severe secondary arthrosis. Hemophilic arthropathy with symptoms of incapacitating knee pain, not responding to medical treatment, associated with an impaired function is a clear indication for total knee replacement (TKR). Primary goals of total knee arthroplasty (TKA) are pain relief and satisfactory function which depends on adequate joint stability and motion. A well-balanced hemostasis is a basic requirement for successful interventions in hemophilic patients. Furthermore, the postoperative range of motion (ROM) depends on many factors, including surgical technique, preoperative motion, and appropriate rehabilitation.We report on our experience with 7 arthroplasties of knee joint arthropathies in 7 patients with severe hemophilia A (n = 4) and severe hemophilia B (n = 3). Indication for total knee replacement was arthropathy in stage III–V, progressive joint destruction, flexion contracture, axial malalignment, and pain refractory to conservative treatment. The average age of the patients at the time of arthroplasty was 35 years (range 18–42 years). Three patients were seropositive for HIV and HCV, 1 patient for HIV, 1 patient for HCV, and 2 patients had no viral infections. Mean hospitalization was 16.7 days (range 14 – 21 days). Six of 7 patients received a non-constrained bicondylar TKA (LCS complete n=5, Rotaglide n=1) and one patient a constrained bicondylar TKA (custom-made prostheses). The TKAs were inserted using bone cement containing gentamycin. Implantation was performed after arterial closure via medial dissection. Surgery was covered by appropriate factor VIII or IX replacement therapy with episodic bolus injections (factor VIII activity aimed at 100%). Median consumption of coagulation factor was 113.742 units (range 55.000 – 157.000 units). The postoperative blood loss was approximately 831 ml blood (range 250–1200 ml) in the low-vacuum drainage systems, the mean range of preoperative and postoperative haemoglobin (13.8 g/dl vs. 9.3 g/dl) was 4.5 g/dl. Transfusion of red blood cells was not required in any of the 7 individuals. Postoperative thromboembolic prophylaxis with low molecular weight heparin (4000 IE/day) was performed in all patients. The short-term results after a mean follow-up interval of 22 month (range 2–59 months) revealed no peri- and postoperative thromboembolic or bleeding complications and no infections. In 6 of 7 patients the knee extension improved with an average from 29.3° preoperatively to 5° postoperatively. One patient with reduced compliance (left hospital contrary to medical advice, rejected rehabilitation) suffered from postoperative articular fibrosis which made an open arthrolysis 3 and 8 month postoperative necessary and brought benefit in ROM from flexion/extension pre-operative 100/30/0 to 80/0/0 postoperative. In summary, our interdisciplinary treatment protocol demonstrates that total knee arthroplasty can be performed in high- risk hemophilic patients with a low rate of complications and in improvement in quality of life because of pain-relief and increase of motility and function in all patients. The high-dose replacement therapy is justified by the clinical outcome and benefit to the patients.

Current concepts of total knee arthroplasty.

Total knee arthroplasty has become a reliable surgical procedure to treat painful degenerative arthritis. Pain relief and functional improvement is excellent and can allow patients to maintain an active lifestyle. Criteria for the type of prostheses selected should include diagnosis, age, functional level, severity of the disease, and patient expectations. Improved instrumentation, attention to surgical detail, including soft tissue balancing of the knee, and the use of polyethylene inserts greater than 8 mm have led to excellent long-term results and low failure rates. Recent improvements in revision total knee systems should significantly improve the long-term results of revision knee arthroplasty. The addition of modular implants has greatly increased the versatility of most systems and allows the surgeon to custom tailor the implant, contingent upon the amount of bony and ligamentous deficiency of the knee. The future goals of total knee arthroplasty include the development of knee systems that mimic normal joint kinematics with improved fixation and decreased polyethylene wear rates.