Minimally Invasive Total Knee Arthroplasty Research Articles

Determination of reference intervals for knee motor functions specific to patients undergoing knee arthroplasty.

In patients with knee osteoarthritis (KOA) undergoing knee arthroplasty (KA), lower-limb motor function tests are commonly measured during peri-surgical rehabilitation. To clarify their sources of variation and determine reference intervals (RIs), a multicenter study was performed in Japan. We enrolled 545 KOA patients (127 men; 418 women; mean age 74.2 years) who underwent KA and followed a normal recovery course. The surgical modes included total KA (TKA), minimally invasive TKA (MIS-TKA), and unicompartmental KA (UKA). Motor functions measured twice before and two weeks after surgery included timed up-and-go (TUG), maximum walking speed (MWS), extensor and flexor muscle strength (MS), and knee range of motion (ROM). Multiple regression analysis was performed to evaluate their sources of variation including sex, age, BMI, and surgical mode. Magnitude of between-subgroup differences was expressed as SD ratio (SDR) based on 3-level nested ANOVA. SDR≥0.4 was set as the threshold for requiring RIs specific for each subgroup. Before surgery, age-related changes exceeding the threshold were observed for TUG and MWS. Between-sex difference was noted for extensor and flexor MS, but extension and flexion ROMs were not influenced by sex or age. After surgery, in addition to similar influences of sex and age on test results, surgical modes of UKA and MIS-TKA generally had a favorable influence on MWS, extensor MS, and flexion ROM. All motor function test results showed a variable degree of skewness in distribution, and thus RIs were basically derived by the parametric method after Gaussian transformation of test results. This is the first study to determine RIs for knee motor functions specific to KOA patients after careful consideration of their sources of variation and distribution shapes. These RIs facilitate objective implementation of peri-surgical rehabilitation and allow detection of patients who deviate from the normal course of recovery.

Analysis of learning curve of minimally invasive total knee arthroplasty: A single surgeon's experience with 4017 cases over a 9-year period.

To evaluate a single surgeon's experience with minimally invasive total knee arthroplasty (MIS-TKA) and report the 9-year learning curve and trends in clinical outcomes based on assessment of surgical skills, radiographic alignments, and patient's function scores. This retrospective study included a total of 4107 knees from 3403 patients undergoing bilateral or unilateral MIS-TKA between March 2004 and February 2013. MIS-TKA was performed through a modified mini-midvastus approach. Postsurgical care regime was standardized for all patients. Data of consecutive 3-month intervals were collected and compared for changes of trends in outcomes over time, including tourniquet time, intraoperative complications, radiographic alignment, the Knee Society Score (KSS), and functional scores. Significant increase in the number of cases undergoing MIS-TKA per 3-month interval over the study period was observed. As surgeon's experience increased over time, tourniquet time was decreased from an average of 70 minutes to approximately 35 minutes. A total of 65 (1.68%) intraoperative complications were recorded and the frequencies were in a significant decreasing trend. The rate of malalignment was in a decreasing trend and steady desired alignment (6°) was achieved at the 15th three-month interval. KSS and function scores increased from 87.4 to 91.5 and 92.6 to 96.8, respectively. Although a surgeon may become competent with MIS-TKA and achieved the preliminary learning curve within one year, experience accumulation continuously improved technical proficiency in MIS-TKA. This study confirmed significant improvements in surgical skills, postoperative alignment, and patients' function over time.

Does Obesity Affect Clinical and Radiological Outcomes in Minimally Invasive Total Knee Arthroplasty? Minimum 5-Year Follow-up of Minimally Invasive TKA in Obese Patients.

BackgroundThe aim of this study was to evaluate the clinical and radiological outcomes of minimally invasive total knee arthroplasty (MIS-TKA) in obese patients.MethodsWe examined the records of 371 cases of MIS-TKA performed using the mini-midvastus approach from January 2006 to December 2006. According to body mass index (BMI), the cases were classified into group A (BMI < 25 kg/m2, 114 knees), group B (25 kg/m2 ≤ BMI < 30 kg/m2, 179 knees), and group C (BMI ≥ 30 kg/m2, 78 knees). Clinical outcomes were measured with the Hospital for Special Surgery Score and Knee Society Score. Radiological evaluation included measurements of knee alignment.ResultsMIS-TKA was performed on all patients. The skin incision size in group A, group B, and group C was 8.2 ± 0.8 cm, 8.3 ± 0.8 cm, and 8.5 ± 0.9 cm, respectively, and the operation time was 86.4 ± 10.4 minutes, 85.9 ± 11.3 minutes, and 89.0 ± 11.4 minutes, respectively, indicating no significant difference among the groups (p > 0.05). There was no difference in terms of the accuracy of the tibial implant alignment, with 97.6%, 95.2%, and 93.4% of each group showing 90° ± 3° varus angulation (p > 0.05). With respect to the accuracy of the femorotibial angle, 93.9%, 94.6%, and 90.2% of each group had 6° ± 3° valgus angulation, with group C demonstrating the lowest level of accuracy (p < 0.05). The preoperative range of motion and Knee Society Score of group C were less than those of groups A and B (p < 0.05), but there was no notable difference among groups at the postoperative 3-month and 1-year follow-ups (p > 0.05).ConclusionsMIS-TKA in obese patients showed satisfactory clinical and radiological results without significant difference in surgical results compared to nonobese patients.

Mini-subvastus versus medial parapatellar approach for total knee arthroplasty: a prospective randomized controlled study.

Whether minimally invasive total knee arthroplasty (MIS-TKA) could offer better and faster recovery without the deviation of post-operative prosthesis position and limb alignment is still controversial. This prospective and randomized study was conducted to compare the clinical and radiological outcomes between patients who underwent the mini-subvastus approach of MIS-TKA and those who underwent the medial parapatellar approach of traditional TKA. Fifty patients, including 50 knees, who required TKA due to osteoarthritis were randomized to the mini-subvastus group (group I) or the medial parapatellar group (group II). All patients accepted the same method of anaesthesia, equal support therapy and identical rehabilitation exercise after surgery. The evaluation system included operation time, tourniquet time, blood loss, skin incision length in flexion, straight leg raising time, the time of lower limb muscle strength up to grade 4, the time of walking with aid or without aid, the time of walking up and down the stairs, the active flexion angle, range of movement (ROM), the Knee Society Scores (KSS), visual analogue score for pain (VAS), hospital stays and radiographic outcomes. The mini-subvastus approach offered smaller skin incision length in flexion, but at the cost of operation time (P < 0.001). No significant difference was found in tourniquet time and blood loss. The patients in group I could achieve straight leg raising, the lower limb muscle strength up to grade 4, walking with or without aid, and walking up and down the stairs earlier (P < 0.001). The active flexion angle, ROM, VAS and KSS in group I were superior to those in group II until six months post-operatively (P < 0.001), but the differences was not apparent at 12months post-operatively. More importantly, there was no significant difference between the two groups on radiological outcomes (P > 0.05). The mini-subvastus approach could offer faster recovery, less pain and shorter hospital stays without compromising the principles of proper prosthesis position and limb alignment compared with the medial parapatellar approach.

AQUACEL® Ag Surgical Dressing Reduces Surgical Site Infection and Improves Patient Satisfaction in Minimally Invasive Total Knee Arthroplasty: A Prospective, Randomized, Controlled Study.

The use of modern surgical dressings to prevent wound complications and surgical site infection (SSI) after minimally invasive total knee arthroplasty (MIS-TKA) is lacking. In a prospective, randomized, controlled study, 240 patients were randomized to receive either AQUACEL Ag Surgical dressing (study group) or a standard dressing (control group) after MIS-TKA. The primary outcome was wound complication (SSI and blister). The secondary outcomes were wear time and number of dressing changes in the hospital and patient satisfaction (pain, comfort, and ease of use). In the intention-to-treat analysis, there was a significant reduction in the incidence of superficial SSI (0.8%, 95% CI∶ 0.00–2.48) in the study group compared to 8.3% (95% CI∶ 3.32–13.3) in the control group (p = 0.01). There were no differences in blister and deep/organ-space SSIs between the two groups. Multivariate analysis revealed that AQUACEL Ag Surgical dressing was an independent risk factor for reduction of SSI (odds ratio: 0.07, 95% CI: 0.01–0.58, p = 0.01). The study group had longer wear time (5.2 ± 0.7 versus 1.7 ± 0.4 days, p < 0.0001) and lower number of dressing changes (1.0 ± 0.2 versus 3.6 ± 1.3 times, p < 0.0001). Increased patient satisfaction (p < 0.0001) was also noted in the study group. AQUACEL Ag Surgical dressing is an ideal dressing to provide wound care efficacy, patient satisfaction, reduction of SSI, and cost-effectiveness following MIS-TKA.

Chronic Kidney Disease Is an Independent Risk Factor for Transfusion, Cardiovascular Complication, and Thirty-Day Readmission in Minimally Invasive Total Knee Arthroplasty

BackgroundLittle is known about the relationship between chronic kidney disease (CKD) and minimally invasive total knee arthroplasty (MIS-TKA). We hypothesized that CKD was an independent risk factor for postoperative complications and increased blood transfusion in patients following MIS-TKA. MethodsA retrospective review of a prospective database was conducted on patients who underwent MIS-TKAs at an academic medical center between 2009 and 2012. Glomerular filtration rates (GFRs) were calculated for each patient at the time of surgery and a CKD group of 205 patients (GFR < 60 mL/min) were matched at a ratio of 1:2 with 410 patients showing a GFR ≥ 60 mL/min (control group). There were no differences between the 2 groups regarding age, gender, body mass index, and American Society of Anesthesiologists grade. Patient characteristics, comorbidities, preoperative hemoglobin, calculated total blood loss, transfusion rate, length of stay, and postoperative complications were compared between the 2 groups. ResultsThe CKD group had lower preoperative hemoglobin levels; higher preoperative comorbidities with cardiovascular disease, diabetes mellitus, and gout; longer length of stay; and higher total blood loss than the control group. Multivariate logistic regression showed that CKD was an independent risk factor for transfusions (odds ratio [OR] 7.6, 95% confidence interval [CI] 4.79-12.21, P < .001), cardiovascular complication (OR 5.5, 95% CI 1.68-9.39, P = .002), and 30-day readmission (OR 6.2, 95% CI 1.98-12.18, P = .005). ConclusionBased on our data, CKD is an independent risk factor for blood transfusion, cardiovascular complication, and 30-day readmission in patients undergoing MIS-TKA.

Associations between venous thromboembolism onset, D-dimer, and soluble fibrin monomer complex after total knee arthroplasty.

BackgroundPrevention and early detection of venous thromboembolism (VTE) is important after arthroplasty of the lower limb. The purpose of this study was to investigate the associations between VTE and hemostatic markers after minimally invasive total knee arthroplasty (MIS-TKA).MethodsWe performed a retrospective study of 50 patients (55 knees) who underwent primary unilateral MIS-TKA with periodic determination of D-dimer and soluble fibrin monomer complex (SFMC) concentrations and with ultrasonography. The development of symptomatic and asymptomatic VTE, location of deep venous thrombosis (DVT; proximal or distal), changes in SFMC and D-dimer concentrations, and correlations between hemostatic markers and VTE onset were evaluated.ResultsTwenty-six patients (47 %) had an asymptomatic distal DVT, but none had proximal DVT, pulmonary embolism, or symptomatic DVT. DVT was detected at postoperative day 1 (POD1) in 16 patients, POD3 in six, and POD5 in three (excluding detections of the same DVT in the same position on different days). DVT onset correlated significantly with SFMC concentration on POD1 and with D-dimer concentration on POD3. The D-dimer concentration did not differ significantly between patients who developed DVT (DVT+) and those who did not (DVT−) at each postoperative time. SFMC concentration differed between DVT+ and DVT− patients only on POD1. Analysis of each hemostatic marker classified as either within or outside the normal concentration range showed no significant correlations between D-dimer concentration and DVT onset at each period. There were significant correlations between SFMC concentrations and DVT onset on POD1 and POD3. There were also significant correlations between D-dimer positive (+) findings and/or SFMC+ findings and DVT onset on POD1 and POD3. D-dimer+ and/or SFMC+ findings had better specificity on POD1 and a positive predictive value on POD1 and POD3 compared with SFMC+ alone.ConclusionsSFMC concentration is an effective hemostatic marker for early detection of DVT. D-dimer concentration alone has limited value as a hemostatic marker for early detection of DVT. Measurement of both D-dimer and SFMC concentrations might be a more sensitive diagnostic tool than measuring SFMC concentration alone.

Serum C-reactive protein distribution in minimally invasive total knee arthroplasty do not differ with distribution in conventional total knee arthroplasty.

Minimally invasive total knee arthroplasty (MITKA) has been developed to reduce surgical trauma and facilitate rehabilitation after arthroplasty. A plausible hypothesis is that this reduced trauma results in lower concentrations of circulating inflammatory biomarkers, such as C-reactive protein (CRP). In this study, we compared CRP concentrations in patients undergoing MITKA to those undergoing conventional TKA (CTKA). Eight hundred and seven patients undergoing MITKA were prospectively recruited. CRP was measured before operation and on days 2, 4, 21, and 42 after operation. Two hundred and forty-seven patients who had CTKA were collected retrospectively, with the same inclusion and exclusion criteria as those who had MITKA. We found in both groups, that CRP values rose abruptly after operation, with peak values reached on day 2 or 4. Values then declined so that by days 21 and 42 they were only modestly above baseline values. Throughout the entire study period, mean CRP in MITKA patients did not differ significantly from those in CTKA patients. However, a significantly higher proportion of CTKA patients than of MITKA patients had peak CRP values at day 4 rather than at day 2 (76.8% vs 42.5%), a difference that was more pronounced in women. Also, by day 42, CRP values were still above baseline in 18.5% of MITKA patients and 28.8% of CTKA patients without known complications. In conclusion, CRP distribution pattern was similar in patients who received MITKA or CTKA,. CRP values remained slightly elevated in both MITKA and CTKA patients for as long 42 days after operation. These findings suggest that MITKA is no less traumatic than CTKA, as determined by CRP values, and the patterns of postoperative CRP may be useful in the management of TKA patients.

A comparison of registration errors with imageless computer navigation during MIS total knee arthroplasty versus standard incision total knee arthroplasty: a cadaveric study

Optimal component alignment in total knee arthroplasty has been associated with better functional outcome as well as improved implant longevity. The ability to align components optimally during minimally invasive (MIS) total knee replacement (TKR) has been a cause of concern. Computer navigation is a useful aid in achieving the desired alignment although it is limited by the error during the manual registration of landmarks. Our study aims to compare the registration process error between a standard and a MIS surgical approach. We hypothesized that performing the registration error via an MIS approach would increase the registration process error. Five fresh frozen lower limbs were routinely prepared and draped. The registration process was performed through an MIS approach. This was then extended to the standard approach and the registration was performed again. Two surgeons performed the registration process five times with each approach. Performing the registration process through the MIS approach was not associated with higher error compared to the standard approach in the alignment parameters of interest. This rejects our hypothesis. Image-free navigated MIS TKR does not appear to carry higher risk of component malalignment due to the registration process error. Navigation can be used during MIS TKR to improve alignment without reduced accuracy due to the approach.

Bleeding in Knee Arthroplasty: Age, Drained Volume, and Ischemia Time.

Drainages in primary knee arthroplasty remain unclear. Our aim is to analyze variables that may affect bleeding in knee arthroplasty (age, drained volume, and ischemia time). We included 188 knee arthroplasties, divided into three groups: conventional approach for total knee arthroplasty (TKA), minimally invasive total knee arthroplasty (MIS), and unicompartmental knee arthroplasty (UNI). Main variables analyzed for the present study were age, drained volume, and ischemia time. Other recorded variables were operated knee, pre- and postoperative hematocrit, diagnosis, comorbidities, and transfusions required. No relationship between age and drained volume was observed. However, patients younger than 70 years presented a major rate of survival curve bleeding. A statistically significant difference was found between drained volume in UNI in contrast to TKA and MIS. There was a significant relationship between time and bleeding at 24 hours postoperative, observing that the greater the bleeding, the longer it would keep bleeding (log-rank, p < 0.001). No statistically significant difference was observed between ischemia time during surgery and a variation in the survival curve. In conclusion, there is a significant relationship between drained volume and time (24 hours). No relationship was found between age or ischemia time and drained volume.

C-reactive protein (CRP) in different types of minimally invasive knee arthroplasty

C-reactive protein (CRP) is an acute-phase biomarker responding to surgical trauma. Typically, a first peak is observed at day 2 with a reduction at day 4 and normalization 3-6 weeks after surgery. CRP is often linked to prosthetic joint infection when elevated values are present longer time after surgery. The aim of this study was to analyse the kinetics of CRP in different types of minimally invasive (MI) arthroplasty and to observe if there were significant differences in between MI total knee arthroplasty (TKA), patient-specific instruments (PSI) TKA and unicompartmental arthroplasty (UKA). Three hundred and seventy-two patients were prospectively studied with a blood test measuring CRP at day 2, 4, 21 and 42 in 3 different groups of patients: 257 MI TKA, 55 PSI TKA and 60 UKA. Mean peak values and kinetics were compared in between different groups of MI arthroplasty. There was a significant age difference in the three MI arthroplasty groups. The difference in mean age for the conventional MI TKA group of 68.8 ± 9.8 years, 58.5 ± 11.7 years for the unicompartmental group (P < 0.05) and 63.3 ± 9.6 years for the PSI group (P < 0.05) was significant. Mean CRP level, for the entire study group, on day 2 was 16.7 ± 8.8 mg/dl that gradually decreased to 13.6 ± 7.8 mg/dl on day 4. On day 21 and 42, median CRP level was 0.6 (0-20) and 0.4 (0-7) mg/dl, respectively. Peak CRP values were lower for UKA compared to TKA at day 2 (11.6 vs. 17.5 mg/dl) and day 4 (8.0 vs. 15 mg/dl), but this was not observed for PSI-assisted arthroplasty (18.9 vs. 17.5 mg/dl). There was a trend for faster CRP normalization in UKA compared to the two other groups at day 21 and at day 42 and for PSI TKA to have a lower mean level at 4 days (12.9 vs. 15 mg/dl). There was no statistical difference in the normalization rate of PSI-assisted versus MI TKA. Kinetics of CRP in MI arthroplasty are identical to the published kinetics of conventional TKA. Most patients normalize CRP at 3 weeks; however, 18 % does not by 6 weeks. This is not a sign of early prosthetic joint infection. Peak values are significantly lower for UKA but not for PSI TKA.

Minimally invasive total knee arthroplasty through a quadriceps sparing approach: a comparative study

To evaluate the short term clinical results of minimally invasive total knee arthroplasty (MIS-TKA) through a quadriceps sparing (QS) approach compared with a standard TKA using a medial parapatellar exposure. Between March 2005 and March 2006, 26 consecutive unilateral primary MIS-TKA through a QS approach were performed. It was compared that the short term clinical results of this group with an age-matched and sex-match cohort of total knee arthroplasty done with a standard medial parapatellar approach. Length of incision, tourniquet time, blood loss, flexion degree, visual analog scale (VAS) score, Knee Society score, tibiofemoral angle and the ability to do a straight leg raising maneuver were evaluated respectively. The mean follow-up time were 17 months (range 12-23 months). The average length of incision was (9.5+/-1.5) cm in the QS group and (14.0+/-2.3) cm in the standard group (P<0.05). Average tourniquet times were (83+/-16) minutes in the QS group and (55+/-11) minutes for the standard group (P<0.05). Postoperative tibiofemoral angles averaged (5.7+/-1.5) degrees valgus in the QS group knees and (6.0+/-1.4) degrees valgus in the standard group knees (P>0.05). The average VAS scores were significantly lower at the first, the third and the seventh postoperative days in the QS group compared with that of the standard group, and the difference was not significant after 6 weeks between two groups. Mean flexion at one week was greater for the QS group (107+/-12) degrees than that in the standard group (95+/-11) degrees. Improved ROM also was seen 6 and 12 weeks postoperatively in the QS group with significant difference. There were no differences in ROM between the two groups in 12 months. The ability to straight leg raised at one week postoperatively was better in the QS group (23/26, 88%) than that of the standard group (21/33, 64%). At the 6 weeks follow-up, the average knee score was (78+/-15) points in the QS group and (71+/-20) points for the standard group (P<0.05). Deep vein thrombosis were found in 1 case of the QS group and 3 cases for the standard group. One patient in the QS group developed superficial wound necrosis that healed uneventfully. There were no other complications such as deep infection, neurovascular injury and so on. The MIS-TKA through a QS approach is associated with a more rapid functional recovery and improves range of motion. But higher specifications and more restrictive indications are of importance with the QS technique.

Internet Promotion of Minimally Invasive and Computer-Assisted Orthopedic Surgery in Total Knee Arthroplasty by Members of the American Association of Hip and Knee Surgeons

Minimally invasive (MIS) and computer-assisted orthopedic (CAOS) surgical options in total knee arthroplasty (TKA) have recently prompted increased discussion despite there being few controlled studies evaluating the efficacy and safety of these options. One of the responsibilities of the members of a specialty society such as the American Association of Hip and Knee Surgeons (AAHKS) is to disseminate accurate information concerning the procedures they perform. The study addresses the question, “What is the level of promotion of MIS and CAOS TKA through the Internet sites of AAHKS members?”

Minimally Invasive Total Knee Arthroplasty with an Optimized Subvastus Approach

A modified subvastus approach to the knee that markedly facilitates minimally invasive (MIS) knee replacement surgery is described. Using a readily available set of retractors the surgeon can perform the surgery without guesswork and without free-hand cuts, thereby maintaining surgical accuracy and patient safety. This MIS-optimized subvastus approach is a reliable, reproducible and efficient means of performing MIS total knee arthroplasty. The technique is amenable to step-wise surgeon learning and can be applied to a wide range of patients who require total knee arthroplasty.

Minimal incision total knee arthroplasty: early experience.

Total knee arthroplasty (TKA) has evolved during the past 30 years to a well-defined technical surgery with excellent results for as many as 20 years of followup. The concepts of exposure, ligament balancing, and joint alignment have been established clearly by Insall and others. In the early 1990s, Repicci introduced minimally invasive surgery for unicondylar knee arthroplasty. This approach suggested that less invasive surgery could accomplish similar results to those of standard unicondylar knee arthroplasty. Early reports in the literature support these conclusions. It only was logical that the minimally invasive surgery approach eventually would be applied to TKA. It is extremely important to establish a clear definition of the minimally invasive surgery and, then, to follow the results. We have completed 70 minimally-invasive TKAs during the past 9 months with early results that indicate less intraoperative blood loss, shorter length of stay, increased range of motion (ROM), with similar implant accuracy to standard TKA. These new procedures will require thorough evaluation as with any new clinical endeavor. It also is of paramount importance to remember that the main goal of any new technology is to advance the science of medicine without compromising the ultimate result for the patient. The early findings are encouraging for the future of minimally invasive TKA and we hope to improve the technology during the next few years.