Arterial Stiffness, Assessed Using the Cardio-Ankle Vascular Index, before and 2 Years after Total Knee Arthroplasty in Patients with Knee Osteoarthritis.

Purpose: Cardiovascular disease (CVD) is a major risk factor for mortality in patients with osteoarthritis, and such comorbidities increase the risk of postoperative complications following total knee arthroplasty (TKA). Arteriosclerosis plays a major role in hemodynamic dysfunction and CVD; however, the postoperative changes in arteriosclerosis following TKA have not been evaluated. Therefore, we assessed the postoperative changes in arteriosclerosis using the cardio-ankle vascular index (CAVI) in patients undergoing TKA, and its relationships with preoperative patient characteristics. Methods: Arteriosclerosis was prospectively evaluated in 119 consecutive patients (140 knees) (15 males (17), 104 females (123); median age 73 years) with knee osteoarthritis who underwent TKA. CAVI was measured before and 2 years after TKA, and the relationships between CAVI and preoperative age, sex, BMI, physical activity status, comorbidities, clinical score, triglyceride concentration, cholesterol concentration, and smoking history were analyzed. Results: CAVI remained stable or improved in 54 joints (39%) and worsened in 86 joints (61%) 2 years post-operation. The median difference between pre- and postoperative CAVI was 0.2 (-0.3, 0.8), and the only preoperative factor associated with this change was preoperative CAVI (r = -0.469, p < 0.001). No other preoperative factor had a significant effect on postoperative arteriosclerosis. Conclusions: The results suggest that patients who undergo TKA subsequently show less severe arteriosclerosis, and the protective effect of TKA on arterial stiffness is greater in those with a higher preoperative CAVI. TKA may be an effective means of reducing the deterioration of arteriosclerosis associated with knee osteoarthritis, at least in the relatively short term.

Patient factors impacting localization of popliteal artery before total knee arthroplasty.

PURPOSE: Intraoperative injury to the popliteal artery (PA) should be avoided during total knee arthroplasty (TKA). This study was performed to clarify the preoperative localization of the PA and the patient factors that impact its localization as a preventive measure. METHODS: Ninety-seven patients (110 knees; 18 men, 79 women) with osteoarthritis who underwent primary TKA were retrospectively reviewed. Preoperative sagittal magnetic resonance imaging was used to measure the distance between the PA and the closest point at three levels: the femoral epicondyle (DPF), the tibial articular surface (DPAS), and the posterior tibial cortex (DPT). All variables are expressed in millimeters as median (interquartile range). RESULTS: The median distance was 10.35 (7.90-12.34) mm for DPF, 6.32 (5.12-8.57) mm for DPAS, and 3.76 (2.28-5.26) mm for DPT. Body height and weight showed weak correlations with DPF (r = 0.324, p < 0.001 and r = 0.207, p = 0.03, respectively). DPF was smaller in women [9.82 (7.64-12.23) mm] than in men [11.27 (10.26-12.75) mm] (p = 0.004). A larger flexion angle and range of motion showed a weak negative correlation with DPT (r = - 0.282, p = 0.003 and r = - 0.236, p = 0.016, respectively). Multiple regression analysis revealed that DPF was related to body height (ß = 0.341, p < 0.001) and that DPT was related to the flexion angle (ß = - 0.264, p = 0.005). CONCLUSIONS: Special attention should be paid to women with a small physique on the femoral side and/or patients with a large flexion angle on the tibial side as a strategy to prevent PA-related complications.

Positive effect of total knee arthroplasty on progression of arteriosclerosis evaluated by cardio-ankle vascular index.

INTRODUCTION: Physical function is expected to improve with an increase in physical activity owing to improvement in knee joint pain after total knee arthroplasty (TKA). This study was performed to evaluate the impact of TKA on arteriosclerosis by measuring the cardio-ankle vascular index (CAVI) before and after surgery. MATERIALS AND METHODS: In total, 206 consecutive patients undergoing unilateral TKA were investigated. The CAVI, an index of the overall stiffness of the artery from the origin of the aorta to the ankle, was used to evaluate the degree of arteriosclerosis. The CAVI of the TKA side and non-TKA side was compared before and 1 year after TKA. RESULTS: There were no differences in the CAVI before and after TKA on the TKA side and non-TKA side, although these values should have worsened at 1 year compared with preoperative values. The CAVI, which did not differ between the two sides preoperatively, differed significantly between the two sides postoperatively (p = 0.013). A generalized linear model showed no interaction between each time point and the measured sides in terms of the CAVI. The relationship between the preoperative CAVI and the difference between the preoperative and postoperative CAVI were examined, showing that R = - 0.428 (p < 0.001) for the TKA side and R = - 0.416 (p < 0.001) for the non-TKA side (significant negative correlation). CONCLUSIONS: The lack of significant age-related deterioration over time on both sides suggests that TKA may slow the progression of arteriosclerosis, especially on the operated side. The effect of TKA was found to be greater with a higher CAVI (i.e., more advanced arteriosclerosis).

Comparison of Operative Times in Primary Bilateral Total Knee Arthroplasty Performed by a Single Surgeon.

Purpose: Prolonged operative time (OT) is associated with adverse complications after total knee arthroplasty (TKA). The purpose of this study was to determine whether preoperative factors, such as sex, age, body mass index, body weight (BW), body height, American Society of Anesthesiologists grade, tibiofemoral angle, hospital for special surgery scores, surgical side, surgical order, and calendar year of surgery, affect OT. Methods: One hundred and nineteen patients (238 knees) with osteoarthritis who underwent staged bilateral primary TKA performed by a single surgeon were evaluated. The medical records of 15 males and 104 females were retrospectively reviewed. All variables were expressed as median (interquartile range). Results: The OT for all TKAs was 57 min (51, 65). The OT on the left side (59 min (52−67)) was longer than that on the right side (55 min (50−62)) (p = 0.015). Multiple regression analysis revealed that longer OT was related to BW (ß = 0.488, p < 0.001), calendar year of surgery (ß = −0.218, p< 0.001), and operative side (ß = −0.151, p = 0.007). The Jonckheere−Terpstra test showed a trend toward decreasing OT with calendar year on the left side (p = 0.037) (surgeon's non-dominant side), but not on the right (p = 0.795). Body height, BW, and body mass index showed weak correlations (r = 0.212, p = 0.001; r = 0.352, p < 0.001; r = 0.290, p < 0.001, respectively) with OT. Conclusion: Patients with a large physique, and especially obesity, with an affected knee on the surgeon's non-dominant side may require a longer OT; OT decreased over time.

Preoperative characteristics and intraoperative factors do not correlate with accomplishments of active straight-leg raising, standing up, and walking after primary total knee arthroplasty.

BACKGROUND: The correlations between patient characteristics and early postoperative functional performances after total knee arthroplasty have not been adequately studied. The purpose of this study was to clarify the effects of preoperative characteristics (sex, age, body mass index, American Society of Anesthesiologists grade, hospital for special surgery score) and intraoperative factors (duration of surgery and tourniquet use) on the time required to accomplish active straight-leg-raising, standing up, and walking as the objective performances for the initiation of early postoperative rehabilitation. METHODS: This cross-sectional retrospective study included 307 patients (384 primary total knee arthroplasties). Postoperative times required until each activity was accomplished were measured. Various preoperative characteristics and intraoperative factors that might affect three objective performances were evaluated. RESULTS: The postoperative times required before each activity was accomplished were 1.5 ± 0.5 days for active straight-leg-raising, 1.2 ± 0.5 days for standing up, and 1.4 ± 0.7 days for walking. There were no significant correlations between any factor (age, body mass index, hospital for special surgery score, duration of surgery, and tourniquet use) and the three objective performances using Spearman's correlation coefficient. There were no differences in sex or American Society of Anesthesiologists grade for three objective functional assessments by Wilcoxon rank sum test. CONCLUSIONS: Differences in patient preoperative characteristics and intraoperative factors are unlikely to affect three objective functional performances in the early postoperative period. Therefore, there is no need to consider differences between patients when initiating early postoperative rehabilitation.

Predictive factors for longer operative times in patients with medial knee osteoarthritis undergoing total knee arthroplasty.

BACKGROUND: Prolonged operative time has frequently been implicated as a risk factor for various complications after total knee arthroplasty (TKA). We aimed to determine whether preoperative factors such as sex, age, body mass index (BMI), prosthetic design, tibiofemoral angle (TFA), range of motion, coronal laxity, Hospital for Special Surgery score and periarticular bone mineral density (BMD) affect operative time. METHODS: We evaluated 164 patients (187 knees) with medial osteoarthritis who underwent primary TKA performed by a single surgeon. The medical records of 27 males and 137 females (median age of 77 and 72 years, respectively) were retrospectively reviewed. TFA was measured on non-weightbearing, standard radiographs. We used dual-energy X-ray absorptiometry to measure BMD, and an arthrometer to evaluate total coronal laxity in each patient. RESULTS: According to univariate analyses, there was a weak positive correlation between BMI and operative time (r = 0.265, p < 0.001), between TFA and operative time (r = 0.235, p = 0.001) and between BMD of the femur and tibia and operative time (r = 0.280, p < 0.001, r = 0.286, p < 0.001, respectively). No significant correlations were found between the other factors and operative time. Based on multivariate analyses, only BMD of the tibia and TFA were significantly correlated with operative time (ß = 0.418, p < 0.001 and ß = 0.182, p = 0.007, respectively). CONCLUSIONS: TFA and BMD of the tibia were the variables more strongly correlated with operative time. Surgeons should recognize preoperatively that patients who have increased TFA, higher periarticular BMD, and higher BMI may have longer operative times. LEVEL OF EVIDENCE: Level IV retrospective study.

Mobile-bearing total knee arthroplasty implants combined with surface cementation produced satisfactory clinical and radiographic outcomes at the 5-year follow-up.

PURPOSE: Very little is known about the use of combined surface cementation (only tibial tray) and mobile-bearing tibial components in total knee arthroplasty (TKA). This study was investigated whether the index combinations show satisfactory clinical outcomes after mobile-bearing TKA using posterior cruciate ligament (PCL)-retaining meniscal-bearing (MB) and PCL-substituting rotating-platform (RP) TKA designed using different anteroposterior constraints. METHODS: This study is a retrospective evaluation of a prospective database. Five-year postoperative clinical outcomes were assessed in 127 patients (127 knees) and 122 patients (122 knees) who underwent TKA with an MB and RP design, respectively. The Hospital for Special Surgery (HSS) score, range of motion, loosening/radiolucency, and subsidence around both components were evaluated in the two designs. RESULTS: The postoperative median HSS score was excellent in both the MB and RP groups (93 and 92, respectively). Postoperative flexion and extension did not differ between the two designs. Neither design showed > 2-mm radiolucencies raising concern for femoral or tibial implant stability. Five (2%) of 249 patients (5 knees) (MB, n = 4; RP, n = 1) showed detectable subsidence of the tibial component. However, no revision TKA had been performed by the 5-year follow-up because no patients had complaints severe enough to necessitate revision surgery. CONCLUSIONS: Clinically good outcomes comparable with previous studies were obtained 5 years after mobile-bearing TKA with surface cementation using both MB and RP implant designs. Thus, equivalent mid-term clinical outcomes of the index combination can be obtained with other implant designs and cementation techniques. LEVEL OF EVIDENCE: Level II.

Mediolateral coronal laxity does not correlate with knee range of motion after total knee arthroplasty.

INTRODUCTION: It remains controversial whether coronal laxity after total knee arthroplasty (TKA) is a critical factor in determining clinical outcomes such as knee range of motion (ROM). The purpose of this study was to evaluate the correlation between postoperative ROM and coronal laxity, which was defined as the angular motion from the neutral, unloaded position to the loaded position, in patients with medial knee osteoarthritis undergoing TKA. MATERIALS AND METHODS: Preoperative and 1-year postoperative coronal laxity were assessed using radiographs by applying a force of 150 N with an arthrometer. A consecutive series of 204 knees was examined. A knee was defined as clinically "balanced" when the difference between medial and lateral laxity was 3° or less. Active ROM was measured using a goniometer. Values were expressed as median values. RESULTS: The ROM was 105° preoperatively and 110° postoperatively, with the correlation being weak (r = 0.372, p < 0.001) between the periods. The total laxity also revealed a weak correlation (r = 0.270, p < 0.001) between the periods. Preoperative laxity was significantly larger (4° vs. 3°) on the medial side (p < 0.001) and postoperative laxity was larger (4° vs. 3°) laterally (p = 0.001). There was no significant correlation between postoperative ROM and laxity pre- and postoperatively. Additionally, there were no differences in ROM between the balanced and unbalanced groups in the pre- and postoperative periods. CONCLUSIONS: This study indicated that mediolateral coronal laxity in patients with an osteoarthritic knee did not correlate with knee ROM after TKA when 3°-4° of laxity in the medial and lateral orientations was maintained.

Insall-Salvati ratio stabilizes one year after mobile-bearing total knee arthroplasty and does not correlate with mid-to-long-term clinical outcomes.

PURPOSE: It has not been established whether changes in the length of the patellar tendon (LPT) after total knee arthroplasty (TKA) affect clinical outcomes. Therefore, this prospective cohort study aimed to evaluate changes in the LPT over time postoperatively and clarify their impact on clinical outcomes after bilateral TKA, performed with differently designed mobile-bearing (meniscal-bearing and rotating-platform) implants on contralateral knees. METHODS: 51 patients who required staged bilateral mobile-bearing TKA were recruited. LPT was evaluated by measuring the Insall-Salvati ratio (ISR) preoperatively and at 1 week, 6 months, and 1, 2, and ≥ 5 years postoperatively. Hospital for Special Surgery score and range of motion were assessed at the final follow-up. RESULTS: Based on the ISR, there were no differences in the patterns of change between the two types of implant (n.s.). At the 6-month follow-up, the ISRs of both implants had significantly decreased (p = 0.002). Throughout the follow-up, the ISR was significantly lower (p < 0.001) for the meniscal-bearing knees than for the rotating-platform knees. After the 1-year follow-up, there were no further substantial changes in the ISR in either group. There was also no significant correlation between the ISR and clinical outcomes. CONCLUSIONS: LPT decreased after both mobile-bearing TKAs for up to 1 year postoperatively, although the decrease was more significant for the meniscal-bearing knees than the rotating-platform knees. After 1 year postoperatively, however, these conditions had stabilized, with no further changes. Thus, LPT plays a minimal role in mid-to-long-term clinical outcomes after TKA. LEVEL OF EVIDENCE: Therapeutic prospective study, Level II.

Impact of anesthesia modality and mechanical venous thromboembolism prophylaxis on the incidence of symptomatic deep venous thrombosis after TKA.

BACKGROUND: Venous thromboembolic events (VTE) are a common complication of total knee arthroplasty (TKA). Prior studies have discussed the utility of mechanical VTE prophylaxis as a monotherapy for low-risk TKA patients. We assess the incidence of clinically significant deep venous thrombosis (DVT) or pulmonary embolism (PE) in low-risk TKA patients who receive mechanical VTE prophylaxis and undergo spinal, epidural, or general anesthesia for their surgery. METHODS: A retrospective study was performed on consecutive low-risk patients who received a TKA between July 2002 and June 2015 with spinal anesthesia (n = 65), epidural and general anesthesia (n = 154), or general anesthesia alone (n = 152). Patients with spinal anesthesia had mechanical VTE prophylaxis until 15 h postoperatively, when remobilization was permitted. Patients who received epidural or general anesthesia had mechanical VTE prophylaxis for 2 h postoperatively. Notable outcomes included development of clinically symptomatic DVT or PE, patient demographics, and perioperative lab values. Statistical analysis was performed using SPSS 22, with chi-squared and Fisher's exact tests for categorical variables and the Kruskal-Wallis test with Scheffe's method for continuous variables. RESULTS: No clinically symptomatic DVT or PE was diagnosed. Patient demographics were equivocal. A statistically significant decrease in prothrombin and activated partial thromboplastin times were noted in the general anesthesia group, but all measurements were within the normal range. CONCLUSIONS: A short course of mechanical VTE prophylaxis may be appropriate for low-risk patients who can immediately mobilize.

Tibial component coverage and rotational alignment accuracy after mobile-bearing total knee arthroplasty.

BACKGROUND: Tibial component coverage (TCC) and tibial rotational angle (TRA) have been studied simultaneously in simulations, but not in clinical studies after total knee arthroplasty (TKA). The purposes of this study were (1) to evaluate TCC and rotational setting postoperatively in mobile-bearing TKA patients and (2) to compare the results with previously published simulation data. METHODS: We prospectively examined 100 patients who underwent primary TKA using the LCS® Total Knee System (LCS) posterior cruciate ligament-substituting prosthesis. Clinical outcomes, TCC (coverage area of the tibial component over the tibia), and TRA (relative to the femoral transepicondylar axis (TEA)) were assessed. Quantitative three-dimensional computed tomography was used to assess TCC and TRA. All values are expressed as median (25th percentile, 75th percentile) using minus (-) for internal and plus (+) for external rotation. RESULTS: Hospital for Special Surgery scores improved from 46 (36, 50) preoperatively to 92 (90, 92) postoperatively. TRA showed a median divergence of - 2.0° (- 4.75°, + 2.74°). All knees were located within 10° of the TEA (range - 10.0° to + 9.7°). The median TCC of the knees was 82.7% (80.6, 84.7%), and there were no knees that hung over the tibial component in any direction. CONCLUSIONS: The LCS prosthesis had good clinical outcomes, comparable TCC, and improved TRA as compared to previous reports, as all knees were located within 10° of the TEA. Simultaneous optimization of both TCC and TRA may contribute to the excellent long-term outcomes that have been observed with this system. LEVEL OF EVIDENCE: Level II, Prognostic study.

Short-term efficacy and safety of hyaluronic acid injection for plantar fasciopathy.

PURPOSE: Plantar fasciopathy is the most common cause of plantar heel pain and is considered to be a type of enthesopathy. The short-term efficacy, safety, and dose-response relationship of high-molecular-weight hyaluronic acid (HA) was investigated in patients with plantar fasciopathy. METHODS: In this multicenter, prospective, randomized, double-blind, placebo-controlled trial, 168 patients with persistent pain from plantar fasciopathy for more than 12 weeks were randomly assigned to receive 2.5 mL of 1% HA (H-HA), 0.8 mL of 1% HA (L-HA), or 2.5 mL of 0.01% HA (control group) once a week for 5 weeks. The primary endpoint was improvement in visual analogue scale (VAS) score for pain from baseline to week 5. RESULTS: The VAS scores (least squares mean ± standard error) in each group decreased gradually after the start of treatment, a change of -3.3 ± 0.3 cm for the H-HA group, -2.6 ± 0.3 cm for the L-HA group, and -2.4 ± 0.3 cm for the control group, with the H-HA group improving significantly more than the control group (P = 0.029). No serious adverse events were reported. There was no difference between the groups in the incidence rates of adverse drug reactions. CONCLUSION: The administration of five injections of high-molecular-weight HA is an effective treatment with no serious adverse drug reactions and is a conservative treatment option for plantar fasciopathy. This treatment contributed to alleviation of pain in patients with plantar fasciopathy and improvement in their activities of daily living. LEVEL OF EVIDENCE: I.

Clinical relevance of active straight leg raising, standing up, and walking after total knee arthroplasty in a cross-sectional study.

BACKGROUND: Active straight leg raising (ASLR) is used to assess restoration of the quadriceps muscle immediately after total knee arthroplasty (TKA). This study aimed to (1) compare the times required to accomplish ASLR, standing up, and walking after TKA, and (2) evaluate the correlation between the time required to accomplish ASLR and perioperative patient-related factors. METHODS: This cross-sectional study included 271 patients (335 primary TKAs performed using the conventional medial parapatellar approach). Postoperative times required until each activity was accomplished were confirmed. Various factors that might impact ASLR, including prosthetic design, were also evaluated. RESULTS: Post-TKA, it took 1.5 ± 0.5 days to accomplish ASLR, 1.3 ± 0.6 days to accomplish standing up, and 1.4 ± 0.7 days to accomplish walking. There were no significant correlations between any factor and ASLR. Strong correlations were found between the times required to accomplish standing up and walking (p < 0.0001, r = 0.804). There were no significant correlations between the times required to accomplish ASLR and standing up/walking. A longer time was necessary for ASLR accomplishment than for standing up (p < 0.001) and walking (p < 0.001). Standing up was accomplished earlier than walking (p = 0.008). CONCLUSIONS: There was no delay in post-TKA ASLR accomplishment compared with previous reports. No factors affecting ASLR during the perioperative period suggested that ASLR was controlled by factors other than knee joint-related factors. ASLR was not correlated with standing up/walking; hence, the clinical significance of ASLR immediately after TKA for early ambulation is unclear. LEVEL OF EVIDENCE: Prognostic study, Level II.

Anteroposterior translation and range of motion after total knee arthroplasty using posterior cruciate ligament-retaining versus posterior cruciate ligament-substituting prostheses.

PURPOSE: It is still controversial whether anteroposterior (AP) translation magnitude after total knee arthroplasty (TKA) affects clinical outcomes, particularly range of motion (ROM). This study examined the following two questions: (1) are AP translations at the mid- and long-term follow-up different for knees within the same patient treated with posterior cruciate ligament-retaining (PCLR) versus posterior cruciate ligament-substituting (PCLS) mobile-bearing TKA prosthesis designs? (2) Is the ROM at the mid- and long-term follow-up for knees treated with PCLR and PCLS designs correlated with the AP translation? METHODS: Thirty-seven patients undergoing sequential bilateral TKA for osteoarthritis were prospectively enrolled. Patients received a PCLR implant in one knee and a PCLS implant in the other and were followed-up for an average 9.8 ± 3.2 years. The AP translations at 30° and 75° of knee flexion and the ROM of both knees were assessed. RESULTS: The implant design (p < 0.001), but not flexion angle (n.s.), had a significant effect on AP translation. AP translation values were larger in PCLR knees than in PCLS knees at both flexion angles (p < 0.0001). The ROM at the final follow-up in the two implant designs was similar (both 115°, n.s.). There was a weak correlation between ROM and AP translation at 30° in the PCLR knees (r = 0.397, p = 0.015), but no correlation at 75° or in the PCLS knees. CONCLUSIONS: Differently constrained prosthesis designs resulted in significantly different AP translational values within the same patient. This indicates that achieving good clinical outcomes and ROM after TKA may not be strongly influenced by the specifics of each patient's anatomical characteristics, but instead by knee constrainment. Clinically, this means that surgeons should familiarize themselves with the AP translation of the implant being used, as this may be the most important factor for optimizing outcomes after mobile-bearing TKA. Level of evidence II, prospective, comparative study.

Patellar tendon length during knee flexion of meniscal-bearing and rotating total knee arthroplasty implants.

PURPOSE: The length of the patellar tendon after total knee arthroplasty (TKA) has most commonly been compared with preoperative measurements. However, there are no reports that discuss changes in the length of the patellar tendon during knee flexion after TKA. The purpose of this study was to evaluate changes in the length of the patellar tendon during knee flexion and to clarify the impact of changes in patellar tendon strain on the length of the patellar tendon and post-operative range of motion (ROM) after TKA. METHODS: Thirty-six patients undergoing sequential bilateral TKA for osteoarthritis were evaluated. Patients received a meniscal-bearing (MB) implant on one side and a rotating platform (RP) implant on the other and were followed for a median of 115 months (range 60-211 months). The lengths of the patellar tendon at maximum extension, 30°, 60°, 90° and maximum flexion were measured, and the post-operative ROM of both knees were assessed. The effects of implant design and the knee flexion angle on the length of the patellar tendon were analysed using a linear mixed-effects model. The relationship between patellar tendon strain and post-operative knee ROM was assessed using Pearson's correlation coefficients. RESULTS: Post-operative clinical scores were similar for MB and RP implants. Neither the implant design nor the knee flexion angle significantly affected the length of the patellar tendon. The ROMs in the two designs at final follow-up were equivocal (114° in MB, 113° in RP). There was no correlation between patellar tendon strain and ROM in knees with either implant type. CONCLUSIONS: Patellar tendon lengths after mobile-bearing TKA with implants that permitted different anteroposterior constraints were relatively constant at varying degrees of knee flexion. Differences in patellar tendon strain may not impact ROM. These results provide conclusive evidence that the quality of the patellar tendon may play a less important role in ROM after TKA. LEVEL OF EVIDENCE: Therapeutic study, Level II.

Comparison of long-term clinical outcomes after bilateral mobile-bearing total knee arthroplasties using PCL-retaining and PCL-substituting implants in the same patients.

PURPOSE: Whether the posterior cruciate ligament (PCL) should be retained or substituted in total knee arthroplasty (TKA) remains an issue of concern. The purpose of this study was to perform within-patient comparisons of mid- and long-term clinical outcomes after mobile-bearing TKA using PCL-retaining (PCLR) and PCL-substituting (PCLS) implant designs. METHODS: Clinical outcomes were assessed in thirty-eight patients (76 knees) who underwent bilateral scheduled staged TKA with a PCLR design on one side and a PCLS design on the other. Median follow-up periods were 118 months (range 60-211) and 114 months (62-198) in knees with PCLR and PCLS implants, respectively. The preoperative diagnosis for all patients was osteoarthritis. The postoperative clinical results of mobile-bearing TKAs using PCLR and PCLS implant designs were evaluated. RESULTS: The postoperative Hospital for Special Surgery and the new Knee Society Knee Scoring System scores revealed no differences between PCLR and PCLS implant designs. Postoperative flexion and extension also did not differ between designs. Postoperative median femorotibial alignment was 4° for PCLR and 5° for PCLS implants, respectively; this difference was not significant. Six of the knees with PCLR and three of the knees with PCLS implants had radiolucent lines around the tibial prostheses; these were less than 1 mm and nonprogressive. CONCLUSIONS: Clinically good results were obtained at approximately 10 years after mobile-bearing TKA using both PCLR and PCLS implant designs bilaterally in the same patients. These results provide conclusive evidence that equivalent clinical results can be obtained with either implant design. LEVEL OF EVIDENCE: Therapeutic study, Level II.

Quadriceps strength impairment in the mid- to long-term follow-up period after total knee arthroplasty.

PURPOSE: Quadriceps strength impairment after total knee arthroplasty (TKA) continues to be a concern. However, most studies of quadriceps strength have short-term follow-up periods. Whether quadriceps strength impairment occurs in the long-term follow-up period after TKA remains unclear. The purpose of this study was to compare the quadriceps strength between posterior cruciate ligament-retaining (CR) and substituting (PS) design mobile-bearing TKA (1) in the same patients after an average of 10 years and (2) between TKA patients and age-matched controls. METHODS: A prospective, quasi-randomized design was used. Thirty-four patients (68 knees) who underwent bilateral TKA (CR on one side and PS on the other) were followed for a minimum of 5 years, and 35 age-matched controls (70 knees) were evaluated. A handheld dynamometer was used to measure quadriceps isometric strength. For each patient, the maximum value of three trials was used. The ratio of muscle strength to body weight (MS/BW ratio; N/kg) was used to evaluate outcomes. RESULTS: The median MS/BW ratio was 3.3 (range 1.4-10.5) for CR 3.4 (range 0.9-9.3) for PS, and 4.6 (range 0.4-8.8) for controls. The MS/BW ratio did not differ between prosthesis designs, but was significantly smaller in both CR (p = 0.020) and PS (p = 0.024) than in controls. CONCLUSIONS: Posterior cruciate ligament-retaining TKA does not confer a substantial advantage an average of 10 years postoperatively. In addition, quadriceps strength, as measured using a hand-held dynamometer, was significantly lower in both TKA patient groups than in age-matched controls. Clinically, the results of this study indicate that quadriceps-strengthening exercises should be continued in the long term after TKA. LEVEL OF EVIDENCE: II.

Comparing Steri-Strip and surgical staple wound closures after primary total knee arthroplasties.

BACKGROUND: Steri-Strips (3M, Two Harbors, MN, USA) have recently been employed for skin closures after orthopedic surgeries. Here we compare the performance of Steri-Strips and skin staples for wound closure after primary total knee arthroplasties (TKAs). METHODS: A total of 76 consecutive osteoarthritic knees (71 patients) that underwent a primary TKA at our facility were included in this study. Thirty-eight knees received Steri-Strips for wound closure and were evaluated prospectively. The other 38 knees were closed with skin staples (Staple group) and evaluated retrospectively. RESULTS: No deep or superficial infections developed in this series. Although Steri-Strips detached from three knees during the 10-day postoperative period, no dehiscence was observed. Thirteen knees developed blisters around the surgical incision in the Steri-Strip group compared with five knees in the Staple group. The average operative time for the Steri-Strip group was 60.6 min (SD 7.3) compared with 54.1 min (SD 6.9) in the Staple group. There were significant differences in operative time (p < 0.001) and tourniquet time (p < 0.001) between the two groups. The average time until patients were permitted to start showering was significantly shorter in the Steri-Strip group (p = 0.0496). The material cost for Steri-Strips was approximately $3.00 USD for one operation compared with $26 USD for skin staplers. CONCLUSIONS: Wound closure with Steri-Strips after a TKA does not require postoperative material removal and may have improved safety, comfort, cosmesis and cost-effectiveness compared with traditional skin closures. LEVEL OF EVIDENCE: Level II, Prognostic study.

Changes in the three-dimensional load-bearing axis after mobile-bearing total knee arthroplasty.

BACKGROUND: The purpose of this study was to assess changes in the three-dimensional (3D) load-bearing mechanical axis (LBMA) preoperatively and at 3 weeks and more than 1-year follow-up after total knee arthroplasty (TKA), and effects of the degree of constraint in the anteroposterior (AP) direction because of the retention of the posterior cruciate ligament (PCL) and the implant design on the changes in LBMA. METHODS: We evaluated 157 knees from 131 patients, including 79 knees that received meniscal-bearing-type (PCL-retaining) and 78 knees that received rotating-platform-type (PCL-substituting) prostheses. Quantitative 3D computed tomography was used to assess changes in the location of the pre- and postoperative LBMA at the tibial plateau level. RESULTS: Changes in the 3D axis were mainly found from medial to lateral and posterior to anterior in both implant designs with no significant differences. Change in the mediolateral (ML) direction was improved soon after TKA, but change in the AP direction improved more gradually over time. The different constraints in the AP direction because of the retention of the PCL and different implant designs did not affect the changes in the LBMA. CONCLUSIONS: The LBMA in the AP direction more than 1 year postoperatively, as well as the LBMA in the ML direction at 3 weeks, appears to shift toward the location found in normal knees after TKA, regardless of the type of prosthetic constraint. These changes may be an important factor that influences the periarticular knee bone mineral density which load bearing may be related to. LEVEL OF EVIDENCE: Level II, Prognostic study.