A longer operative time will lead to the development of any postoperative complications in total knee arthroplasty (TKA). According to previous reports, a significant increase in TKA procedure time done by novice surgeons was observed compared to high-volume surgeons. Our purpose was to investigate and to clarify the important maneuver necessary for novice surgeons to minimize a surgical time in TKA. A total of 300 knees in 248 patients, averaged 74.6 ± 8.7 years, were enrolled. All primary TKAs were done using same instruments (Balanced Knee System®, PS design, Ortho Development, Draper, UT) and same measured resection technique at 14 facilities by 25 orthopedic surgeons. Surgeons were divided into three surgeon groups (4 experts, 9 medium volume surgeons, 12 novices). All methods were approved by our institution's ethics committee. We divided the operative technique into 5 steps to make comparisons of step-by-step surgical time among surgeon groups of different levels. We defined Phase 1 as performing surgical exposure from skin incision to insertion of the intramedullary rod into the femur. Thereafter, the distal and AP surface of the femur, proximal tibia, the chamfer and PS box of the femur, and patella were resected in Phase 2. In Phase 3, a setup the trial component and a keel of the tibia were done after a confirmation of appropriate ligament balance using the spacer block. Then, a bone surface was irrigated with 2000ml of saline after the removal of the trial component. Subsequently, permanent components were fixed with use of bone cement in Phase 4. Finally, the final irrigation using 2000ml saline and wound closure were done in Phase 5. Every phase of the surgical time was recorded in each TKA. As a statistical analysis, operation data including length of skin incision, component size, operation time in each phase, and ratio of surgical time in each phase to whole surgical time, were compared using non-repeated measures of ANOVA and a post hoc Bonferroni correction. The threshold for statistical significance was set at a p value of less than 0.05.Introduction
Methods
Total knee arthroplasty (TKA) provides good results even for severe knee osteoarthritis (OA) patients. However, patients often suffer from post-operative pain and have long rehabilitation periods. In recent years, utilization of unicompartmental knee arthroplasty (UKA) has increased in an effort to decrease pain and shorten recovery compared to TKA. Moreover, the long-term results of the UKA have improved. Many surgeons now wonder whether TKA or UKA is better for patients with isolated medial knee OA. In Japan, the government has public insurance system and patients are able to receive the joint replacement surgery inexpensively. This study was conducted to compare the cost the public insurance and the patients co-payment for TKA and UKA. We investigated a series of thirty TKAs and fifteen UKAs performed in Fussa Hospital (Tokyo, Japan) from July 2012 to April 2013. Data from two TKAs' were excluded since the patients had comorbidities (asthma and severe DM) that extended their hospitalizations. Patients were discharged from the hospital if they were able to go up and down the stairs or were able to conduct routine activities of daily living. Total payments the hospital received averaged $19600 (S.D. $1600) for a TKA and $15200 (S.D. $1300) for a UKA. Patients paied averaged of $690 (S.D. $370) for a TKA and $470 (S.D. $170) for a UKA (Figure 1). The surgical fee was $3769 for both TKA and UKA, and was uniform thoughout Japan. The implant price averaged $6200 (S.D. $300) for TKA and $3900 (S.D. $200) for UKA, where prices were also determined by the government. Hospitalization averaged 28 days (S.D. 7 days) for TKA and 21 days (S.D. 6 days) for UKA. For both TKA and UKA, the total cost and the number of days in hospital were highly correlated (R = 0.92 and R = 0.96, respectively). A linear cost model suggests the TKA cost was $210 times days of hospitalization plus $13100 and the UKA cost was $220 times days of hospitalization plus $10000. Patients' payments were not correlated to the days of hospitalization (R = 0.22 and R = 0.45, respectively). TKA and UKA are performed all over the world now and the number of the surgeries increases each year. Althouth each country has a different insurance system, many countries face an increasing and problematic economic burden for both patients and insurance organization (either public or private company). This study showed UKA is less expensive than TKA by $4400, an advantage that might complement the traditional view that UKA is less invasive and often has fewer complications for treating isolating medical compartment OA. For Japanese system, patients pay relatively little out-of pocket despite long hospitalization, and length of stay has a direct and significant effect on total cost for TKA and UKA
Bi-cruciate substituting total knee arthroplasty (TKA) having two post-cam mechanisms was developed to substitute for cruciate ligament function after surgery. A previous study has shown many of these knees achieve high functional flexion. However, there is little information provided to differentiate between knees able to flex deeply and those that could not, although this is a major concern for surgeons. This study was conducted to compare the kinematic pathway from 0° to 90° in both groups. Twenty five knees were included in this study. All knees were diagnosed with osteoarthritis (OA) and all TKAs were performed by the same surgeon (WR) from November 2005 to September 2006. A mini mid-vastus surgical approach with posterior cruciate ligament (PCL) resection and patellar resurfacing was used in all cases. Computer navigation was used to guide bone cuts in all the cases. Patients' age averaged 63 years (range, 43–73) at the time of surgery. The study observations were performed at an average of 53 (SD 4) months after surgery. Knee motions were recorded using video-fluoroscopy while subjects performed stair up and down, and lunge activities. The three-dimensional position and orientation of the implant components were determined using model-based shape-matching techniques. This initial manual solution was refined using nonlinear least-squares optimization to maximize image-edge correspondence. Joint kinematics were determined from the three-dimensional pose of each implant component using Cardan/Euler angles. TKAs were divided into two groups according to the maximum lunge angles; TKAs achieved larger than 130° were defined as high flexion group (H group) and the ones from 110° to 130° were defined as moderate flexion group (M group). Tibial internal position and the AP locations of medial and lateral condyles were examined. Two TKAs were excluded since their maximum flexion was less than 110°. Twelve and eleven TKAs were defined as the H group (High flexing, average 137°, SD 4°) and the M group (Moderate flexing, average 121°, SD 5°), respectively. Tibial internal rotation averaged 10° (SD 4°) and 9° (SD 3°), respectively, at lunge position. The medial and the lateral condyles were located at 9 mm (SD 2 mm) and 17 mm (SD 3 mm) posterior to the tibial centerline during the lunge activity in the M group and at 11 mm (SD 2 mm) and 21 mm (SD 3 mm) in the H group. Tibial rotation was not statistically different (Figure 1), while AP position of the lateral condyle translated more backward in H group at 90° (Figure 2). The TKAs in the M group exhibited femoral forward motion from 0° to 20° flexion, while the H group moved backward (Figure 2). Our results revealed the post-cam mechanisms worked effectively in the H group TKA. The TKAs which acquired deep flexion successfully prevented the “roll forward motion” and had greater femoral posterior translation at 90° where the posterior post-cam mechanism engages. It appears adequate femoral posterior translation may be important to acquire deep flexion after TKA.
