Low Incidence of Postoperative Complications With Navigated Total Knee Arthroplasty.

Background: A number of postoperative complications of navigated total knee arthroplasty (TKA) have been discussed in the literature, including tracker pin site infection and fracture. In this article, we discuss the low postoperative complication rate in a series of 3100 navigated TKAs and the overall complication rate in a systematic analysis of the literature.

Methods: Three thousand one hundred consecutive patients with navigated TKAs from 2001-2016 were retrospectively evaluated for complications specific to navigation.

Medial over-resection of the tibia in total knee arthroplasty for varus deformity using computer navigation.

We are reporting a series of 35 cases in which downsizing, lateralizing of the tibial baseplate and resection of the uncovered medial plateau bone releases the medial collateral ligament and tightens the lateral collateral ligament. Result in excellent ligamentous balance and correction to neutral mechanical axis. The mean follow up was 32.

Bone mineral density of the femur in autopsy retrieved total knee arthroplasties.

Bone mineral density (BMD), as measured by DEXA, can vary depending on bone rotation and fat content of soft tissues. We performed DEXA measurements, under controlled positioning, on 24 autopsy-retrieved femora from patients who had fully functional and asymptomatic successful TKA to determine periprosthetic BMD changes and compared results to 24 normal cadaveric femora. In TKA specimens, BMD was affected by gender, preoperative diagnosis, and zone under analysis.

Alignment in Total Knee Arthroplasty: Where Have We Come From and Where Are We Going?

Numerous reports have linked malaligned total knee arthroplasty (TKA) components with increased wear, poor functional outcomes, and possibly early failure due to component loosening. Consequently, proper alignment is critical to a successful outcome. This article will review: the normal mechanical alignment of the knee, classical alignment in TKA, anatomic alignment in TKA, intraoperative reference points for alignment, and the potential for new alignment schema based on the kinematic axes of knee movement.

Torsion deformity and joint loading for medial knee osteoarthritis.

Purpose: The consequences of lower limb torsion deformity on knee loading in knee osteoarthritis are poorly understood. The purpose of this study was to quantify the associations between the mechanical axis, tibial torsion and knee loading in subjects with medial knee OA and in controls.

Methods: Twenty-four subjects: end-staged medial knee osteoarthritis (OA) with apparent torsion deformity (TKO, n=6) and without torsion deformity (KOA, n=8) and controls (CON, n=10) were imaged using long standing lower extremity (LSLE) radiographs and computed tomography (CT).

Soft-tissue balancing during total knee arthroplasty in the varus knee.

Soft-tissue balancing during total knee arthroplasty is an important step in optimizing the mechanical balance of the knee joint. Soft-tissue contractures that result from varus coronal plane deformity can pose a difficult problem, and the surgeon should have a standard procedure for managing such situations in the operating room. Balance may be assessed intraoperatively with the use of spacer blocks, laminar spreaders, and tensioning devices as well as by placement of trial components.

The effect of drill hole size on the fixation strength of a cemented prosthetic patellar button.

This study used a cadaver model to analyze the fixation strength of 3 different patellar resurfacing preparations using an all-polyethylene patellar component. One of 3 drill hole sizes was randomly selected and used to prepare the patella. The entire construct was cemented, mounted to a servohydraulic testing machine, cycled between 0 and 50 N, and then tested to failure.

Using an antibiotic-impregnated cement rod-spacer in the treatment of infected total knee arthroplasty.

We present a new option for treatment of post-total knee arthroplasty periprosthetic infection associated with bone destruction and massive loss-use of an antibiotic-impregnated cement rod-spacer. This rod-spacer can be custom- made, at time of surgery, with Steinmann pins, intramedullary nails, Rush rods, Harrington spine rods, bone cement (polymethylmethacrylate), and antibiotics. We used this technique in 9 cases of periprosthetic infection over a 6-year period.

Resection arthroplasty for failed patellar components.

A total of 1,401 primary total knee arthroplasties (TKA) were reviewed; 44 (3.2%) had at least the patellar component revised. Nine of these knees (eight patients) had insufficient bone stock to allow reimplantation of another patellar component.

The treatment of recurrent chronic infected knee arthroplasty with a 2-stage procedure.

We report the case of a patient with recurrent periprosthetic infections after total knee arthroplasty associated with bone destruction and massive bone loss that was successfully treated with a 2-stage procedure-resection arthroplasty with insertion of an antibiotic-impregnated cement rod-spacer and systemic antibiotics and then a resection arthrodesis of the knee with the use of an intercalary allograft fixed with a long intramedullary nail. This technique is a viable option for the treatment of recurrent periprosthetic infections after total knee arthroplasty associated with bone destruction, massive bone loss, and severe instability.

Surgical navigation in adult reconstruction surgery: techniques and clinical experience.

A surgeon's first response to the concept of computer-assisted orthopaedic surgery may be a sense of lost autonomy. However, a system need not and should not be designed to this end. Using the computational ability of the computer system to see beyond the human eye to view the knee with full kinematic dimensions, surgeons have recently made progress in the areas of computer-assisted ligament balancing and in using smart tools for minimally invasive surgery.

Passive knee kinematics before and after total knee arthroplasty: are we correcting pathologic motion?

The change in coronal plane deformity throughout a range of flexion before and after total knee arthroplasty (TKA) has not been reported. Unlike most alignment assessments traditionally reporting coronal plane alignment in a standing position under static conditions, this study reports deformity throughout the flexion arc before and after deformity correction. One hundred fifty-two TKA patients using the anteroposterior axis for femoral component rotation and computer navigation techniques were included in the study.

What would you do? Challenges in hip surgery.

The following are 5 case presentations of interesting and challenging patients with hip pathology.

Patellar meniscus in total knee arthroplasty.

Twenty-four clinically successful, autopsy retrieved porous-coated anatomic total knee arthroplasty (TKA) specimens were evaluated to determine the structure and function of the patellar meniscus. Mean implant duration was 76 months (range: 11-135 months). Histological examination showed the patellar meniscus to be composed of dense fibrous tissue with scattered regions of chronic granulomatous response to polyethylene debris.

Reliability of measuring long-standing lower extremity radiographs.

The mechanical axis of the lower extremity was measured using preoperative long-standing radiographs in 56 patients undergoing total knee arthroplasty with the Stryker Navigation System (Stryker, Kalamazoo, Mich). Each radiograph was measured by four physicians, three times, in random order, and at delayed intervals. Measurements from each physician produced intraclass correlation coefficients of 0.

Pelvic tracker effects on hip center accuracy using imageless navigation.

Objective: Imageless computer assisted total knee surgical systems have commonly relied on determination of the functional rotational center of the femoral head as a landmark for determining the lower extremity mechanical axis. This has been accomplished through range of motion and center of rotation calculations for the femur with respect to the pelvis as the lower extremity is taken through a range of motion. Our study evaluated the use of this algorithm with and without a pelvic tracker attached to the iliac crest.

Effect of one- and two-pin reference anchoring systems on marker stability during total knee arthroplasty computer navigation.

Objective: This study investigated different infrared marker reference base attachments in cadaveric bone and their effects on alignment outcome when different loads were applied.

Material And Methods: Five cadaveric specimens were used to test four reference base attachments: a locking one-pin (4.0 mm and 5.

Extensor mechanism disruption after total knee arthroplasty.

Unlabelled: Extensor mechanism disruption after total knee arthroplasty is a challenging complication for orthopaedic surgeons. The treatment options for repair include observation, direct primary repair, direct primary repair with synthetic ligament or autogenous tissue augmentation, or reconstruction with allograft tissue. A computerized systemic review and literature search was performed to identify the relevant literature on extensor mechanism disruptions associated with total knee arthroplasty.

Flexion and extension gap balancing in revision total knee arthroplasty.

Unlabelled: Revision total knee arthroplasty presents a unique set of problems when attempting to balance flexion and extension gaps. Loss of soft tissue support and established deformity can make balancing difficult. One needs to balance the flexion and extension gap heights as well as medial and lateral symmetry, which may not always be attainable.

Differences between extramedullary, intramedullary, and computer-aided surgery tibial alignment techniques for total knee arthroplasty.

Traditionally, intramedullary and extramedullary tibial alignment techniques are used to obtain neutral alignment during total knee arthroplasty. Computer-assisted techniques are available to aid in obtaining alignment intraoperatively. This study analyzed the difference in tibial alignment using intramedullary and extramedullary techniques, and compared them to the resulting tibial axis as determined by a computer navigation system.

Antibiotic-laden cement: technique for uniform manual mixing.

The use of polymethyl methacrylate has revolutionized surgical technique in total joint arthroplasty. In addition, in an effort to reduce the rate of infections as well as to treat active infections, the practice of adding powdered antibiotics to the cement has become commonplace. A simple and efficient technique of mixing antibiotic powder into cement that creates a uniform distribution of antibiotic is introduced.

Development and validation of a lower-extremity activity scale. Use for patients treated with revision total knee arthroplasty.

Background: Valid outcome measurement tools are required to reliably demonstrate the effectiveness and clinical outcomes of lower-extremity arthroplasty. Having ascertained a lack of a practical and valid measure of the change in actual daily physical activity that occurs prior to and following lower-limb arthroplasty, we developed and validated a lower-extremity activity scale.

Methods: The eighteen-level self-administered scale was developed with the aid of content experts to ensure face validity.

The variability of intramedullary alignment of the femoral component during total knee arthroplasty.

Intramedullary instrumentation for femoral component alignment during total knee arthroplasty is readily used. Newer alignment techniques using computer navigation are now available. This study assesses the difference in the sagittal and coronal plane alignments using a cadaveric model with 3 different entry points for intramedullary alignment compared with a navigation system.