Manipulation Rate Is Not Increased After Customized Total Knee Arthroplasty

Introduction Manipulation under anesthesia (MUA) is a standard treatment for arthrofibrosis after total knee arthroplasty (TKA), with reported rates of 1.5-6%.  Customized TKA may have better outcomes by matching individual patient anatomy.  However, a previous study reported an unacceptably high rate of MUA for customized TKAs.  This study reports the incidence of MUA in a large cohort of second generation customized TKAs.  Methods:Data was collected prospectively on 360 2nd generation ConforMIS iTotal cruciate retaining TKAs.  MUA was performed for clinically significant arthrofibrosis.  Range of motion (ROM) and New Knee Society Scores (KSS) were evaluated at regular intervals for two years.   Results: 11/360 (3.05%) knees underwent MUA.  ROM overall improved from 115° to 125°, and from 112° to 122° in patients undergoing MUA.  KSS objective and functional scores in MUA patients increased from 57 to 98 and 41 to 90, respectively, and in the entire cohort increased from 65 to 96 and 45 to 86 at 2 years (p<0.05). No MUA patients underwent revision surgery.   Discussion and Conclusion:Customized TKA with second generation ConforMIS iTotal implants results in a MUA rate consistent with the literature for all designs. Additionally, patients exhibit significant increases in ROM and Knee Society Scores.  

Customized versus Patient-Sized Cruciate-Retaining Total Knee Arthroplasty: An In Vivo Kinematics Study Using Mobile Fluoroscopy

BACKGROUND

Historically, knee arthroplasties have been designed using average patient anatomy. Recent advances in imaging and manufacturing have facilitated the development of customized prostheses designed to fit the unique shape of individual patients. The purpose of this study is to determine if improving implant design through customized total knee arthroplasty (TKA) improves kinematic function.

METHODS

Using state-of-the-art mobile fluoroscopy, tibiofemoral kinematics were analyzed for 24 subjects with a customized individually made (CIM), cruciate-retaining TKA, and 14 subjects having an asymmetric condylar cruciate-retaining TKA. Subjects performed a weight-bearing deep knee bend and a rise from a seated position. Each patient was evaluated for weight-bearing range of motion, femorotibial translation, femorotibial axial rotation, and condylar liftoff occurrence.

RESULTS

Subjects having a CIM TKA experienced greater weight-bearing knee flexion compared with the traditional posterior cruciate-retaining (PCR) TKA design. During flexion, the CIM TKA subjects consistently exhibited more posterior femoral rollback than the traditional PCR TKA subjects. The CIM TKA was found to have statistically greater axial rotation compared with the traditional PCR TKA (P = .05). Of note, only the CIM TKA patients experienced femoral internal rotation at full extension, as exhibited in a normal knee. Compared with the traditional PCR TKA, the CIM TKAs demonstrated minimal occurrences of paradoxical sliding and reverse rotation during flexion and extension. The CIM TKA subjects showed minimal liftoff and hence better stability in earlyflexion to midflexion compared with the traditional PCR subjects.

CONCLUSION

The CIM TKA demonstrated kinematics more similar to a normal knee. Therefore, using customized implant technology through CIM TKA designs affords benefits including more normal motion compared with a traditional PCR TKA.

Bone Preservation in a Novel Patient Specific Total Knee Replacement

Background: The volume of total knee arthroplasty procedures is growing rapidly and, correspondingly, it is expected that the volume of revision procedures will grow rapidly as well.  Revision surgery is most successful when adequate bone remains on both the tibia and femur to allow for the least invasive revision.  We hypothesized that total knee arthroplasty with a patient-specific implant would result in significant bone preservation as compared to standard total knee arthroplasty with “off-the-shelf” implants. Methods: We evaluated 100 total knee arthroplasties which utilized patient-specific implants, versus 37 standard posterior stabilized and 32 standard posterior cruciate retaining total knee arthroplasties.  Bone resection was quantified utilizing intra-operative measurements of actual resected bone. Additionally we performed a virtual, CAD-based analysis of resections via CT imaging on 15 knees.  Findings: We found that patients had significantly less bone resected in all zones measured, on both the femur and tibia, when patient-specific implants with patient-specific jigs were used.  When assessed volumetrically with CAD imaging, standard implants resected 12-49% more bone than did patient-specific implants, depending on the size of the implant utilized. Interpretations: Utilizing patient-specific implants in total knee arthroplasty results in significant bone sparing as compared to standard total knee arthroplasty. This has the potential for less invasive revision surgery in the future, possibly obviating the need for dedicated revision implants or augments and other bone substituting devices.

In situ leg length measurement technique in hip arthroplasty

In situ femoral preparation refers to implanting a femoral component before the femoral neck osteotomy and without dislocating the hip joint, which allows the implanted femoral component to be used to measure leg length and offset. One hundred hip arthroplasty surgeries among 93 patients were compared with a control group of 15 patients. A modular neck femoral component was implanted in a technique similar to implanting a femoral nail. The differences between the in situ measurements and the preoperative and postoperative radiograph measurements averaged -0.1 mm for leg length (r = 0.89) and -0.37 mm for offset (r = 0.57). In situ leg length measurement allows accurate measurement of leg length and offset and guides surgeons in selecting appropriate modular components to attain a near anatomical hip arthroplasty.

Factors affecting bony impingement in hip arthroplasty

Computer modeling of 10 patients' computed tomographic scans was used to study the variables affecting hip arthroplasty range of motion before bony impingement (ROMBI) including acetabular offset and height, femoral offset, height and anteversion, and osteophyte removal. The ROMBI was compared with the ROM before component impingement and the native hip ROM. The ROMBI decreased with decreased total offset and limb shortening. Acetabular offset and height had a greater effect on ROMBI than femoral offset and height. The ROMBI lost with decreased acetabular offset was not fully recoverable with an increase in femoral offset or osteophyte removal. Bony impingement increased and component impingement decreased with decreased acetabular offset and increased head diameter.

Specificity of a Bacteroides thetaiotaomicron marker for human feces

A bacterial primer set, known to produce a 542-bp amplicon specific for Bacteroides thetaiotaomicron, generated this product in PCR with 1 ng of extracted DNA from 92% of 25 human fecal samples, 100% of 20 sewage samples, and 16% of 31 dog fecal samples. The marker was not detected in 1 ng of fecal DNA from 61 cows, 35 horses, 44 pigs, 24 chickens, 29 turkeys, and 17 geese.

Eastern Black Walnut Plantations: An Economically Viable Option for Conservation Reserve Lands Within the Corn Belt

The financial returns to establishing eastern black walnut plantations in the Corn Belt region are financially acceptable. Roughly one million acres lend themselves to walnut culture. Stumpage price and site quality reflected through land price influence the level of returns realized. These plantations can provide a viable land use and investment alternative in utilizing erodible land, in diversifying the rural economy, and over the long run in supplementing farm income. North. J. Appl. For. 4:158-160, Sept. 1987.