Comparison of two minimally invasive implantation instrument-sets for total knee arthroplasty
Department of Orthopedic Surgery, University Teaching Hospital, Medical University of Innsbruck, Carinagasse 47, 6800 Feldkirch, Austria.Knee Surgery Sports Traumatology Arthroscopy (Impact Factor: 3.05). 10/2009; 18(3):359-66. DOI: 10.1007/s00167-009-0957-z
Several choices of instrument systems are available for minimally invasive surgical approaches. There are reports that one alternative, the quadriceps sparing, side-cutting instrumentation, results in diminished implantation accuracy. A total of 108 patients were randomized to undergo TKA either using side-cutting implant instrumentation (Group A) or anterior-posterior mini-incision instrumentation (Group B). All TKAs were operated on with a minimal invasive, mini-midvastus surgical approach. 50% of the TKAs were performed with computer-assistance in each cohort. The radiographic parameters, clinical outcomes and knee scores were evaluated preoperatively and 3 months postoperative. In Group B, we found significantly higher accuracy for the mechanical axis of the limb (range +/-3 degrees: Group A 54% versus Group B 89%, p = <0.001), medial proximal tibial angle (range +/-3 degrees: Group A 85% versus Group B 98%, p = <0.027) and tibial slope (range +/-3 degrees: Group A 59% versus Group B 85%, p = <0.007). The application of the navigation system could only significantly reduce outliers (accuracy >3 degrees) in Group B. Clinical outcomes and knee scores were similar in both groups and were not influenced by computer-assistance. Using the anterior-posterior, mini-incision instruments for minimally invasive TKA will lead to higher implantation accuracy when compared to the quadriceps sparing side-cutting instrumentation. The navigation technique could not compensate for shortcomings of the side-cutting instrumentation. The clinical relevance of this study is that the quadriceps sparing side-cutting instrumentation should not be used for TKA because of unacceptable reduced implantation accuracy.
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ABSTRACT: 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.
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ABSTRACT: Minimally invasive and robot-assisted procedures have potential advantages when used for total knee arthroplasty (TKA). The purpose of this cadaveric study was to examine whether robot-assisted minimally invasive procedures improve TKA alignment after modifying the robotic techniques and instruments.Total knee arthroplasties were performed on 10 pairs of fresh cadaveric femora. Ten knees were replaced using the robot-assisted minimally invasive technique and 10 using the conventional minimally invasive technique. After prosthesis implantation, limb and prosthesis alignments were investigated by measuring mechanical axis deviation, femoral and tibial sagittal and coronal inclination, and femoral rotational alignment with 3-dimensional computed tomography scans. Postoperative alignment accuracy of the implanted prostheses was better in the robot-assisted minimally invasive TKA group than in the conventional minimally invasive TKA group as judged by the rotational alignment of the femoral component (0.7°±″.3° vs 3.6°±2.2°, respectively) and the tibial component sagittal angle (7.8°±1.1° vs 5.5°±3.6°, respectively). One sagittal inclination outlier for the tibial side existed in the robotic minimally invasive TKA group, and 2 outliers for the mechanical axis, 2 for the tibial side sagittal inclination, and 2 for the femoral rotational alignment existed in the conventional minimally invasive TKA group.Higher implanted prostheses accuracy and fewer outliers in postoperative radiographic alignments can be attained with robot-assisted TKA. Minimally invasive TKA in combination with an improved robot-assisted technique is an alternative option to compensate for the shortcomings of conventional minimally invasive TKA.
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