[雙語翻譯]醫(yī)學外文翻譯--全膝關節(jié)置換術中假體位置對于假體-骨撞擊前的最大屈膝角度的影響（英文）

1、Effect of Total Knee Arthroplasty Implant Position on Flexion Angle Before Implant-Bone ImpingementHideki Mizu-uchi, MD, PhD,*y Clifford W. Colwell Jr., MD,* Shuichi Matsuda, MD, PhD,y Cesar Flores-Hernandez, BS,* Yukihi

2、de Iwamoto, MD, PhD,y and Darryl D. D'Lima, MD, PhD*Abstract: We generated patient-specific computer models of total knee arthroplasty from 10 patients to compute maximum flexion angle before implant-bone impingement

3、. Motion was simulated for 5 different femoral implant positions and 11 different tibial insert positions at 4 different tibial posterior slopes. In the neutral position, the mean maximum flexion angle was 136.3°. T

4、he range because of anatomical variation among patients was 13.0°. A combination of 2- mm posterior translation of the femoral component with a 10-mm anterior translation of the insert and a 7° posterior slope

5、increased flexion by a mean of 14° relative to the neutral position. The rate of change in flexion angle was 0.4°/mm to 1.5°/mm with respect to implant position and 1.5°/mm increase in the posterior c

6、ondylar offset. Keywords: total knee arthroplasty, knee flexion angle, computer simulation, component position, anatomical variation. © 2011 Elsevier Inc. All rights reserved.Total knee arthroplasty (TKA) has become

7、 one of the most successful orthopedic procedures with reported survival rates of greater than 90% after 15 years [1,2]. With the improvement of long-term outcomes, there is renewed interest in maximizing range of motion

8、 after TKA [3-10]. The range of motion in flexion is extremely important in Asian countries and for patients with lifestyles that involve sitting on the floor in deep flexion [3]. Even in North American patients, up to 7

9、5% identified that activities requiring deeper knee flexion angle such as squatting, kneeling, and gardening were performed with greater difficulty after TKA [4]. Many clinical studies have investigated factors affect- i

10、ng postoperative range of motion [5,6,10,11]. Patient- related factors (such as preoperative range of motion, body mass index, disease, age, and sex) greatly influence the postoperative range of motion. Similarly, surgic

11、al techniques can also affect the postoperativerange of motion. Examples include the height of joint line, patellar tracking, appropriate gap balancing, release of posterior capsule, and removal of the osteophytes. Anoth

12、er important factor is the posterior condylar offset (PCO), which has been associated with postoperative range of motion in fluoroscopic analysis in vivo [5]. Previous studies have analyzed the effect of implant alignmen

13、t and relative position on postoperative range of motion [12-15]. Walker et al [12] reported that posterior and proximal femoral placement and a greater posterior tibial slope increased maximum flexion angle in plastic m

14、odels of the femur and tibia. Massin and Gournay [13] demonstrated that greater PCO increased tibial posterior slope, and a more posterior femorotibial contact point can increase flexion in a study that used 2-dimensiona

15、l templates of prosthetic components on lateral knee radiographs. However, the combined effect of the 3-dimensional anatomy of the patient and the implant position has not been studied. We generated patient-specific anat

16、omical models of implant-bone impingement to evaluate the effect of implant position and anatomical variation on flexion angle. Our primary hypothesis was that implant position would significantly affect maximum knee fle

17、xion angle before bone-prosthesis impingement. Our secondary hypothesis was that the PCO would correlate significant- ly with maximum flexion angle.From the *Shiley Center for Orthopaedic Research and Education at Scripp

18、s Clinic, La Jolla, CA; and yDepartment of Orthopaedic Surgery, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan. Submitted April 19, 2010; accepted August 1, 2010. No benefits or funds were receive

19、d in support of the study. Reprint requests: Darryl D. D'Lima, MD, PhD, Shiley Center for Orthopaedic Research and Education at Scripps Clinic, 11025 N. Torrey Pines Road, Suite 140, La Jolla, CA 92037. © 2011 E

20、lsevier Inc. All rights reserved. 0883-5403/2605-0011$36.00/0 doi:10.1016/j.arth.2010.08.002721The Journal of Arthroplasty Vol. 26 No. 5 2011insert. A constant mass was applied at a fixed distance (300 mm) from the clini

21、cal epicondylar axis of the femur to generate a flexion moment because of gravity. The femur was then allowed to flex, and the maximum flexion was recorded before impingement between the posterior cortex of the femur and

22、 the tibial insert (Fig. 2). Peak flexion angles were recorded as the insert was moved at 2-mm intervals ranging from 10-mm anterior to 10-mm posterior for each of the 5 femoral implant positions (neutral, 2-mm anterior/

23、posterior, and 2-mm proximal/distal from the neutral). This process was then repeated for each of 4 tibial posterior slope angles (0°, 3°, 5°, and 7° to the mechanical axis of the tibia). We also meas

24、ured the PCO for each of the different femoral implant positions as depicted in Fig. 1B. Posterior condylar offset was measured as the maximum distance between the posterior surface of the distal femur and the posterior

25、condyle [5].Validation of the Computer Model Four fresh-frozen human cadaver knees were tested to validate the computer model. Computed tomographic scans were obtained after implanting fiducial markers in each tibia and

26、femur (3 titanium screws in each bone). Knee arthroplasty was performed using a surgical navigation system (Stryker Navigation, Freiburg, Germany). Component alignment was similar to that described for the computational

27、model. Scorpio CR (Stryker Orthopaedics) tibial and femoral componentswere used; the patella was not resurfaced. All soft tissues around the knee joint were removed as much as possible except the posterior cruciate ligam

28、ent, the medial and lateral collateral ligaments, and the extensor mechanism after arthroplasty. The tibia was mounted vertically on a custom rig, and the femur was allowed to flex passively under gravity similar to the

29、setup of the computer model. The fiducial markers were used to register the components and bones using the surgical navigation system. Knee kinematics and component position were measured. The maximum passive flexion pos

30、sible without subluxation was recorded. For computational model validation, subject-specific models were con- structed using the bone geometry from CT scans from the 4 cadaver knees and the geometry of implants used as d

31、escribed above. Experimentally measured maximum flexion angles were compared with those predicted by the computational model.Results Repeated measures analysis of variance were per- formed to measure differences in maxim

32、um flexion for the various implant positions. Bonferroni-corrected post hoc tests were used to determine the significance of the difference in maximum flexion for each condition relative to neutral position. Spearman ran

33、k correlation was used to detect the strength of the linear correlation between PCO and maximum knee flexion angle. Power analysis determined that a sample size of 10 was sufficient to detect a difference in maximum flex

34、ion angle of 3° or greater with a power of 0.90, assuming an SD of 2.5°. Maximum flexion angles measured experimentally in cadaver knees was 142.0° ± 3.6° (mean ± SD; range, 138.0°-146.

35、0°). Computer-simulated maximum flexion using models generated from cadaver CT scans was 147.2° ± 4.9° (range, 142.8°-151.8°), which was similar to that experimentally measured, with an aver

36、age absolute error of 5.2° ± 1.6° (range, 3.1°-6.8°). In 2 of all 10 knees, the femur had to be translated anteriorly by greater than 1 mm (2.3 and 4.9 mm) to avoid notching of the anterior corte

37、x. The difference in flexion angle between the mechanical axis and the anatomical axis was 3.1° ± 1.1° (range, 1.2°-4.5°). We therefore aligned the femoral component to the ana- tomical axis of t

38、he femur to assess any effect on anteroposterior position. The measured anteroposterior translation of anatomically aligned components was less than 1 mm relative to the translation of the components aligned to the mecha

39、nical axis. With the components in neutral position, the mean maximum flexion angle for 10 knees was 136.3° ± 4.7° (range, 130.70°-143.7°). The variation in flexion in our cohort of 10 knees was

40、13.0°, which reflects the variation in patient anatomy of our cohort. With the posterior slope of the tray set to 0°, a more proximalTable 1. Demographic Data and Implant SizeMean age (y) (mean ± SD, range

41、) 74.6 ± 8.1 (57-84) Femorotibial angle (mean ± SD, range) 180.6° ± 4.1° (175°-187.5°) Size 5 (male/female) 0 knee/2 knees Size 7 (male/female) 2 knees/2 knees Size 9 (male/female) 2 kn