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).

Characteristics of hidden blood loss following hybrid total knee arthroplasty.

BACKGROUND: Hidden blood loss (HBL) unrecognized by the usual practice of assessing intraoperative loss and postoperative drainage comprises a considerable proportion of total blood loss (TBL) during primary total knee arthroplasty (TKA). However, HBL has not been adequately investigated in hybrid TKA (uncemented femur, cemented tibia). The purpose of this study was to clarify the amount and influential factors of HBL in hybrid TKA. METHODS: A consecutive series of 151 knees in 137 patients with knee osteoarthritis who underwent hybrid TKA were retrospectively evaluated. We examined the correlations between HBL and various factors of concern for their effects on TBL, including age, sex, body weight (BW), body height, body mass index, operation time, tourniquet time, and visible blood loss (VBL) in three periods (intraoperative: VBL1; until 3 h postoperatively: VBL2; from 3 h to 1 day postoperatively: VBL3). RESULTS: Median (interquartile range) HBL and TBL were 528 (388, 711) mL and 725 (582, 926) mL, respectively. HBL relative to TBL (H/T) was 73%. There were weak correlations between HBL and BW (r = 0.249, p = 0.002) and between HBL and VBL3 (r = -0.261, p = 0.001). Multivariate analyses confirmed a positive correlation between HBL and BW (ß = 0.296, p < 0.001) and a negative correlation between HBL and VBL3 (ß = -0.270, p < 0.001). CONCLUSIONS: Hybrid TKA showed comparable values of HBL and H/T to those reported for cemented TKA. Therefore, management strategies for HBL in hybrid TKA can follow the same protocols used for cemented TKA. High BW and low VBL3 may be predictors of postoperative HBL in hybrid TKA.

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.

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.

Association between bone mineral density distribution and various radiographic parameters in patients with advanced medial osteoarthritis of the knee.

PURPOSE: Patients with severe osteoarthritis (OA) of the knee have changes in bone mineral density (BMD) of the distal femur and proximal tibia. Correlations between the medial-to-lateral BMD (M/L-BMD) ratio (which normalizes the potentially confounding effects of body size and sex on BMD) and radiographic parameters that indicate OA progression have not been adequately studied. The purpose of this study was to evaluate correlations between radiographic indicators of OA progression and femoral and tibial M/L-BMD ratios. METHODS: A consecutive series of 182 knees in 156 patients with advanced medial knee OA who underwent total knee arthroplasty were included. We evaluated correlations between the femoral and tibial M/L-BMD ratios and various radiographic parameters, including tibiofemoral angle (TFA), mechanical axis angle (MAA), tibial coronal angle, tibiofemoral subluxation (%), load-bearing axis deviation at the tibial plateau (%), and medial and lateral laxity. RESULTS: Univariate analyses using Spearman's correlation coefficient revealed significant positive correlations between femoral and tibial M/L-BMD ratios and both TFA and MAA and negative correlations with tibial coronal angle and load-bearing axis deviation. Multivariate analyses showed significant associations between TFA and the femoral M/L-BMD ratio (ß = 0.434, p < 0.001) and between MAA and the tibial M/L-BMD ratio (ß = 0.384, p < 0.001). CONCLUSION: BMD distribution around the knee might be predictable with radiographic parameters such as the TFA for the femur and MAA for the tibia. The findings of this study provide in vivo data on the evaluation of preoperative femoral and tibial M/L-BMD ratios without dual-energy X-ray absorptiometry.

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.

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.

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.

Characteristics and timing of recurrence during postoperative surveillance after curative resection for lung adenocarcinoma.

PURPOSE: To establish the most effective methods of postoperative surveillance to detect early recurrence of lung adenocarcinoma. METHODS: The subjects of this retrospective study were 485 patients with p-stage I-III lung adenocarcinoma, who underwent postoperative surveillance. We examined the sites and detection modes of recurrence and calculated the recurrence-free probabilities. Patients with stage I disease were divided into low- and high-risk recurrence groups using a risk score calculated by assigning points proportional to risk factor regression coefficients. RESULTS: Of the 112 patients with recurrence, 86 had intrathoracic recurrence. Routine computed tomography (CT) revealed recurrence in 60 patients. The recurrence-free probability curves showed that 95% of recurrences were identified within the first 4 years after resection in patients with stage II/III disease. In patients with stage I disease, the predictors of recurrence included male sex, positive pleural lavage cytology, moderate-to-poor differentiation, and visceral pleural invasion. Postoperative recurrences were detected throughout the follow-up period in the high-risk group. CONCLUSIONS: Routine chest CT plays an important role in the postoperative surveillance of lung adenocarcinoma. We recommend intensive follow-up during the early post-resection period for patients with advanced stage disease and long-term follow-up for high-risk patients with stage I disease.

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.

Posterior Cruciate Ligament Retention or Substitution During Total Knee Arthroplasty Does Not Affect Long-Term Bone Mineral Density or Quality.

BACKGROUND: Physical activity is recognized as one of the factors that influence bone mineral density (BMD) and bone quality after total knee arthroplasty (TKA). According to biomechanical analyses after posterior cruciate ligament (PCL) retaining (PCLR) and substituting (PCLS) TKA, each implant design has different kinematics and kinetics. The purposes of this study were: (1) to perform within-patient comparisons of the midterm and long-term effects of PCL retention in mobile-bearing TKA on proximal femur and tibia BMD and calcaneus bone quality measured using ultrasound and (2) to identify correlations between them. METHODS: A prospective, quasi-randomized design was used. Thirty-seven patients (74 knees) who underwent bilateral TKA (PCLR on one side and PCLS on the other) were evaluated. Mean follow-up periods were 118 months (standard deviation 40) and 117 months (standard deviation 36) in knees with PCLR and PCLS implants, respectively. The BMDs of the total hip and proximal tibia and broadband ultrasound attenuation (BUA; dB/MHz) through the calcaneus were measured. RESULTS: The mean BMD of PCLR and PCLS were equivalent at the proximal hip and tibia. The BUA of the calcaneus was also the same between implants. There were significant correlations between the 3 anatomic sites. CONCLUSION: When measured approximately 10 years after TKA, PCL retention had no substantial effect on the BMD of the proximal femur and tibia, or on the bone quality of the calcaneus. The measurement of noninvasive BUA may predict BMD, although further analysis is required.

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.

Macroscopic evaluation of the anterior cruciate ligament in osteoarthritic patients undergoing total knee arthroplasty.

BACKGROUND: Sacrifice of the anterior cruciate ligament (ACL) is currently common practice during total knee arthroplasty (TKA). However, patients who receive an ACL-retaining TKA maintain more normal knee kinematic patterns than those without an ACL. Additionally, satisfactory survival and function more than 20 years after bicruciate-retaining TKA has recently been reported. The purpose of this study was to compare the percentage of knees with a visually intact ACL prior to TKA surgery with previously reported values. METHODS: A total of 247 knees (216 consecutive patients) that underwent TKA were retrospectively evaluated. The preoperative diagnosis for all patients was primary OA. The macroscopic appearance of the ACL at the time of surgery was retrospectively assessed using routinely recorded digital photographs and classified as normal, moderately damaged (fissured), or completely ruptured. Both normal and moderately damaged ACLs were defined as intact. RESULTS: Ninety-four percent (233/247) of the knees had an intact ACL (normal or moderately damaged). This value is higher than that found in previous reports. CONCLUSIONS: Our results show more candidates for bicruciate ligament-retaining TKA surgery than reported previously. This suggests that improved techniques for bicruciate-retaining TKA would be clinically useful and could benefit a large number of patients.

Sonographic swelling of pronator quadratus muscle in patients with occult bone injury.

BACKGROUND: The disarranged fat stripe of the pronator quadratus muscle (PQ) on radiographs (the PQ sign) is reported to be predictive of subtle bone fractures. This study aimed to report the results of magnetic resonance imaging (MRI) study in the patients in whom bone injury was not radiographically detected around the wrist joint, and the PQ was sonographically swollen following acute trauma. METHODS: We evaluated sonographically the PQ of 55 patients who showed normal radiographs following acute trauma. The sonographic appearance of the PQ was checked on both longitudinal and transverse images. On the longitudinal image, the probe was positioned along the flexor carpi radialis tendon. For the transverse image, we adopted the image of the same level in which the PQ of the unaffected hand showed maximal thickness. The PQ was considered to be swollen with disproportionate hyperechogenicity and/or thickening compared with the unaffected side at least in one of the two images. Of the 55 patients, 25 patients whose PQ was considered to be swollen underwent MRI study. PQ thickness in millimeters was retrospectively measured on longitudinal and transverse sonographic images. RESULTS: Twenty-three patients (92.0%) had occult bone injury, and two adult patients (8.0%) showed only wrist joint effusion on MRI. Among these 23, the distal radius was the most frequent location of the occult bone injury (20 patients; 9 [36.0%] with an occult fracture line and 11 [44.0%] with bone bruising). In longitudinal image, the mean value of the PQ thickness of affected hands was 6.2 (3.7-9.6 mm; standard deviation [SD], 1.5) and that of unaffected hands was 4.5 (2.3-6.7 mm; SD, 1.2), respectively. In transverse image, that of dominant and nondominant hands was 7.6 (4.6-13.2 mm; SD, 2.0) and 5.5 (3.6-7.5 mm; SD, 1.1), respectively. The mean difference in PQ thickness between affected and unaffected hands was 1.7 (0.1-5.0 mm; SD, 1.1) in longitudinal image and 2.0 (0.3-6.8 mm; SD, 1.7) in transverse image. CONCLUSIONS: Sonographic swelling of the PQ might be indicative of occult bone injury in patients with normal radiographs following acute trauma.

Bone quality of the calcaneus 5years after total knee arthroplasty.

We used non-invasive broadband ultrasound attenuation (BUA) to determine whether the pre-surgical bone quality of the calcaneus was improved 5years postoperatively, and whether the interval between total knee arthroplasty (TKA) surgeries influenced post-surgical calcaneal bone quality. All patients underwent scheduled, staged, bilateral TKA. Twenty-one patients (42 TKAs) with bilateral knee osteoarthritis were evaluated. One day before and 5years after TKA, BUA through the os calcis on the surgical side was measured. Fourteen out of 21 patients showed post-surgical improvement in BUA bilaterally. When all 42 cases were considered together there was a significant improvement in BUA 5years after surgery (P=0.042). There were no significant correlations between the changes in BUA on each side and the interval between TKA surgeries.

Rotational alignment of tibial components in mobile-bearing TKA: posterior substituted vs. PCL retaining.

PURPOSE: The medial border of the tibial tubercle (MBTT) is one of the fixed anatomic landmarks for tibial component setting during total knee arthroplasty (TKA). In mobile-bearing TKA using a tibial cut first technique, the final tibial component rotation can be guided by the position it achieves following several flexion-extension cycles. In this study, tibial component angle (TCA) and tibial rotational angle (TRA) were determined in dependence of retention or resection of the posterior cruciate ligament (PCL). METHODS: The TCA and TRA were examined in 206 patients who underwent primary TKA (PCL retaining: 104 knees, PCL substituting: 102 knees). The tibial component rotation was intraoperatively setting between the parallel to the axis of the most medial aspect of the tibial tubercle as the anterior anatomic landmark and the center of the tibial component as the posterior landmark at the maximum coverage with the osteotomized tibial plateau with its adjustment after several knee flexion-extension exercises. A postoperative quantitative three-dimensional computed tomography technique was used for measurements by a single observer. RESULTS: The TCA showed a divergence of 0.21° external to the MBTT in the PCL-retaining design and 1.62° internal divergence in the PCL-substituting design. The TRA showed an internal divergence of 0.88° in the PCL-retaining design and an internal divergence of 2.12° in the PCL-substituting design. There were no significant differences between the two designs. CONCLUSIONS: The MBTT might be regarded as a reliable landmark for obtaining an acceptable tibial rotational setting in mobile-bearing TKA despite PCL retention.