Effect of recombinant irisin on recombinant human bone morphogenetic protein-2 induced osteogenesis and osteoblast differentiation.

Osteoporotic fragility fractures substantially impact aging societies, necessitating long-term care and increasing healthcare costs. Myokine irisin, secreted by skeletal muscle, influences bone metabolism; however, a comprehensive understanding of the mechanisms by which irisin affects bone metabolism is still lacking. Therefore, this study aimed to explore the effects of irisin on osteogenesis and osteoblast differentiation triggered by bone morphogenetic protein-2 (BMP-2). We used 4-week-old male ICR mice and implanted polyethylene glycol pellets containing recombinant human BMP-2 (rh-BMP-2) into the left dorsal muscle pouch. Mice received weekly intraperitoneal injections of either phosphate-buffered saline or recombinant irisin (re-irisin). Ectopic bone formation was evaluated 3 weeks post-surgery using micro-computed tomography (µ-CT) and histological analysis. In vitro experiments, C2C12 cells were treated with or without rh-BMP-2 and re-irisin, and we assessed osteoblast differentiation markers, e.g., runt-related transcription factor 2, alkaline phosphatase, osteocalcin, and osteopontin, using real-time reverse transcription-polymerase chain reaction. The µ-CT analyses showed that re-irisin significantly increased bone mineral content and bone volume of ectopic bones newly formed by rh-BMP-2. The gene expressions of the osteoblast markers were significantly increased by rh-BMP-2 and further upregulated by re-irisin. The treatment of cyclic AMP response element-binding protein (CREB) small interfering RNA attenuated these effects, suggesting that CREB signaling pathway was involved in rh-BMP-2/re-irisin-induced osteoblastic differentiation. This study demonstrates the potential of irisin to enhance osteogenesis through BMP signaling, offering insights for osteoporosis treatment and highlighting irisin as a promising therapeutic target for improving bone health and extending a healthy lifespan.

Impact of constrained humeral liner on impingement-free range of motion and impingement type in reverse shoulder arthroplasty using a computer simulation.

BACKGROUND: Dislocation is a major complication of reverse total shoulder arthroplasty (RSA). The humeral liner may be changed to a constrained type when stability does not improve by increasing glenosphere size or lateralization with implants, and patients, particularly women with obesity, have risks of periprosthetic instability that may be secondary to hinge adduction on the thorax, but there are few reports on its impact on the range of motion (ROM). This study aimed to determine the influence of humeral liner constraint on impingement-free ROM and impingement type using an RSA computer simulation model. METHODS: A virtual simulation model was created using 3D measurement software for conducting a simulation study. This study included 25 patients with rotator cuff tears and rotator cuff tear arthropathy. Impingement-free ROM and impingement patterns were measured during flexion, extension, abduction, adduction, external rotation, and internal rotation. Twenty-five cases with a total of 4 patterns of 2 multiplied by 2, making a total of 100 simulations: glenosphere (38 mm normal type vs. lateralized type) and humeral liner constraint (normal type vs. constrained type). There were 4 combinations: normal glenosphere and normal humeral liner, normal glenosphere and constrained humeral liner, lateralized glenosphere and normal humeral liner, and lateralized glenosphere and constrained humeral liner. RESULTS: Significant differences were found in all impingement-free ROM in 1-way analysis of variance (abduction: P = .01, adduction: P < .01, flexion: P = .01, extension: P = .02, external rotation: P < .01, and internal rotation: P < .01). Tukey's post hoc tests showed that the impingement-free ROM was reduced during abduction, external rotation, and internal rotation with the combination of the normal glenosphere and constrained humeral liner compared with the other combinations, and improved by glenoid lateralization compared with the combination of the lateralized glenosphere and constrained humeral liner. In the impingement pattern, the Pearson χ2 test showed significantly greater proportion of impingement of the humeral liner into the superior part of the glenoid neck in abduction occurring in the combination of the normal glenosphere and constrained humeral liner group compared with the other groups (P < .01). Bonferroni post hoc tests revealed that the combination of the normal glenosphere and constrained humeral liner was significantly different from that of the lateralized glenosphere and constrained humeral liner (P < .01). Using constrained liners resulted in early impingement on the superior part of the glenoid neck in the normal glenosphere, whereas glenoid lateralization increased impingement-free ROM. CONCLUSION: This RSA computer simulation model demonstrated that constrained humeral liners led to decreased impingement-free ROM. However, using the lateralized glenosphere improved abduction ROM.

No Impact of Contact Between the Medial Collar of a Hydroxyapatite-Coated Triple-Tapered Stem and the Femoral Neck on Periprosthetic Bone Mineral Density.

BACKGROUND: Hydroxyapatite-coated, triple-tapered, shorter-length stems with a medial collar have been reported with good results for a few years. We investigated whether contact between the medial collar and femoral neck affects clinical outcomes and changes in bone mineral density (BMD) in patients who have this type of stem in their total hip arthroplasty construct. METHODS: This was a retrospective, single-center study involving 62 patients scheduled for unilateral total hip arthroplasty using a hydroxyapatite-coated, triple-tapered, shorter-length stem who were followed for at least 1 year postoperatively. All patients had a Dorr type B femoral canal shape. Contact between the medial collar and the femoral neck was evaluated by computed tomography at the third postoperative month, and patients were classified into 2 groups. Postoperative clinical outcomes were investigated by the Western Ontario and McMaster Universities Arthritis Index and the Japanese Orthopaedic Association scores; radiological evaluation included stem fixation, spot welds and cortical hypertrophy, postoperative 3-dimensional stem alignment, and periprosthetic BMD changes. RESULTS: There were 51 patients in the Contact + group (collar and neck contact) and 11 in the Contact-group (no contact). There were no differences between the 2 groups in the improvement of Western Ontario and McMaster Universities Arthritis Index and Japanese Orthopaedic Association scores, stem fixation, occurrence of cortical hypertrophy, or 3-dimensional stem alignment. Radiolucent lines were present in zones 3, 4, and 5 in 6 patients (12%) in the Contact + group only, who had no statistical difference between the 2 groups. Bone mineral density (BMD) decreased most in zone 7 in both groups, with no difference between the 2 groups. CONCLUSIONS: The presence or absence of contact between the medial collar and femoral neck did not affect postoperative BMD changes or radiological or clinical results. LEVEL OF EVIDENCE: Therapeutic Level III.

Association Between Overhang of the Posterior Femoral Condyle and Restricted Postoperative Knee Flexion Related to Patient-Reported Stiffness in Medial-Pivot Total Knee Arthroplasty.

BACKGROUND: The primary aim of this study was to investigate the association between the posterior longitudinal overhang in the femoral condyle (PLOF) in medial-pivot total knee arthroplasty (TKA) and a change in knee flexion angle (change in flexion). METHODS: This retrospective cohort study included 148 knees undergoing medial-pivot TKA for medial knee osteoarthritis. The primary outcome was the change in flexion (c-flexion) preoperatively and 1-year postoperatively. The component positions were evaluated using 3-dimensional measurements, where the PLOF was measured for each medial and lateral femoral condyle. The secondary outcome was the Western Ontario and McMaster Universities Osteoarthritis Index scores taken preoperatively and 2 years postoperatively. A multivariate regression analysis was performed to determine predictors of c-flexion and risk factors for negative c-flexion (less than 0°). Furthermore, a receiver operating characteristic curve was utilized to determine the threshold for negative c-flexion. RESULTS: The mean c-flexion was -3.2° ± 8.7, and lateral PLOF was significantly associated with c-flexion (ß = -0.52; P < 0.001). Larger preoperative flexion angles (odds ratio, 1.10; P < 0.001) and larger lateral PLOF (odds ratio, 1.69; P = 0.001) were risk factors for negative c-flexion, with thresholds of 129° and 1.1 mm, respectively (sensitivity, 0.79; specificity, 0.72). Additionally, patients who had negative c-flexion (n = 91) demonstrated less improvement in preoperative and 2-year postoperative Western Ontario and McMaster Universities Osteoarthritis Index stiffness subscores than patients who had positive c-flexion (0° or more; n = 57) (P = 0.01). CONCLUSIONS: A larger lateral PLOF was associated with decreased and negative c-flexion after medial-pivot TKA. Patients who had negative c-flexion demonstrated less improvement in knee stiffness. Surgical strategies aimed at minimizing lateral PLOF may enhance postoperative knee flexion and overall patient outcomes in medial-pivot TKA.

Comparative analysis of medial pivot vs. posterior stabilized total knee arthroplasty in patients with valgus deformed osteoarthritic knees: a retrospective cohort study.

PURPOSE: Total knee arthroplasty (TKA) is highly effective for end-stage knee osteoarthritis, providing long-term benefits and anticipated increased prevalence. The study compares Medial Pivot TKA's (MP-TKA) historical success for varus deformities with recent findings suggesting comparable outcomes for valgus deformities. Despite prevalent use of Posterior Stabilized TKA (PS-TKA) for valgus deformities, this research explores the unexplored comparative efficacy of MP-TKA vs. PS-TKA in knee osteoarthritis patients with valgus deformity. METHODS: This single-centre cohort study focused on 57 knees in 53 patients undergoing TKA for knee osteoarthritis with valgus deformity. Conducted between January 2013 and April 2021, the study compared MP-TKA and PS-TKA. Surgeries adhered to a medial parapatellar approach and modified gap technique, with perioperative interventions for pain, bleeding, and swelling. Outcome measurements included knee joint range of motion, radiographic evaluation, patients-reported outcomes, operative time, blood laboratory tests, estimated blood loss, and postoperative adverse events, and analyzed between the two groups. RESULTS: Postoperative hip-knee-ankle angles showed no significant difference between MP-TKA and PS-TKA. The pie crust technique was similarly used in both groups, and deformity correction showed no significant difference. Range of motion and clinical outcomes, measured by WOMAC and JOA scores, were comparable postoperatively. MP-TKA had a shorter surgical duration (p = 0.01), and PS-TKA exhibited higher estimated blood loss (p = 0.01) without significant complications in either group. CONCLUSIONS: This pioneering study compares the outcomes of MP TKA and PS TKA in patients with valgus-deformed osteoarthritic knees. Compared to PS TKA, MP TKA shows a prolonged operative duration and increased blood loss, likely due to the requirement for patellar replacement. However, postoperative range of motion and clinical outcomes are similar. Both groups exhibit favorable midterm clinical results, supporting the viability of MP TKA for valgus deformed knees. The study, consistent in surgical approach, highlights MP TKA's effectiveness for valgus deformities.

A novel imageless accelerometer-based navigation system improves acetabular cup placement accuracy during total hip arthroplasty in the lateral decubitus position.

INTRODUCTION: The accuracy of acetabular cup placement using conventional portable imageless navigation systems in total hip arthroplasty (THA) in the lateral decubitus position remains challenging. Several novel portable imageless navigation systems have been developed recently to improve cup placement accuracy in THA. This study compared the accuracy of acetabular cup placement using a conventional accelerometer-based portable navigation (c-APN) system and a novel accelerometer-based portable navigation (n-APN) system during THA in the lateral decubitus position. MATERIALS AND METHODS: This retrospective cohort study compared 45 THAs using the c-APN and 45 THAs using the n-APN system. The primary outcomes were the absolute errors between the intraoperative and postoperative values of acetabular cup radiographic inclination and anteversion angles and the percentage of cases with absolute errors within 5°. Intraoperative values were shown on navigation systems, and postoperative measurements were conducted using computed tomography images. RESULTS: The median absolute errors of the cup inclination angles were significantly smaller in the n-APN group than in the c-APN group (3.9° [interquartile range 2.2°-6.0°] versus 2.2° [interquartile range 1.0°-3.3°]; P = 0.002). Additionally, the median absolute errors of the cup anteversion angles were significantly smaller in the n-APN group than in the c-APN group (4.4° [interquartile range 2.4°-6.5°] versus 1.9° [interquartile range 0.8°-2.7°]; P < 0.001). Significant differences were observed in the percentage of cases with absolute errors within 5° of inclination (c-APN group 67% versus n-APN group 84%; P = 0.049) and anteversion angles (c-APN group 62% versus n-APN group 91%; P = 0.001). CONCLUSIONS: The n-APN system improved the accuracy of the cup placement compared to the c-APN system for THA in the lateral decubitus position.

Perioperative bleeding control in total hip arthroplasty: hemostatic powder vs. tranexamic acid-a prospective randomized controlled trial.

BACKGROUND: Perioperative bleeding in total hip arthroplasty (THA) can lead to various problems, so effective management of blood loss is needed. This prospective, single-blind, randomized controlled trial aimed to compare the efficacy of topical administration of SURGICEL® (a hemostatic agent of oxidized regenerated cellulose) powder (SP) and tranexamic acid (TXA) in controlling perioperative bleeding during THA. MATERIALS AND METHODS: In total, 114 patients undergoing THA for osteoarthritis were randomized to either group S (THA with SP) or group T (THA with TXA). Data including patient demographics, laboratory data (C-reactive protein [CRP], hemoglobin, and hematocrit), operative time, and intraoperative blood loss were analyzed. Clinical outcomes were assessed using WOMAC, JOA, FJS scores, and visual analog scale (VAS) scores. Primary outcomes were estimated total and postoperative blood loss, while secondary outcomes included hematological test results and various clinical scores. RESULTS: 57 patients were allocated to each group, with 55 in group S and 56 in group T were finally included in the analysis. There was no significant difference (p = 0.141) in estimated total blood loss between group S (788.2 ± 350.1 ml) and group T (714.1 ± 318.4 ml). Hemoglobin and hematocrit levels and WOMAC, and FJS scores were not significantly different between the two groups at any time point. CRP levels were significantly different on postoperative days 4 and 7, and JOA score was significantly different on preoperative and postoperative period. However, the differences in CRP and JOA score values themselves were relatively small and not clinically different. CONCLUSIONS: Topical administration of SP is as effective as TXA in reducing perioperative bleeding in patients undergoing THA. Additionally, no significant difference was observed in early postoperative clinical outcomes between SP and TXA. LEVEL OF EVIDENCE: Therapeutic Level I. TRIAL REGISTRATION: The University Hospital Medical Information Network (UMIN) registration number UMIN000047607.

Comparative analysis of patient-reported outcomes in total knee arthroplasty and total hip arthroplasty: adjusting for demographic influences.

PURPOSE: Total knee arthroplasty (TKA) has consistently demonstrated lower patient satisfaction compared to total hip arthroplasty (THA). However, prior investigations failed to account for the patients' demographic characteristics. This study aimed to conduct a comparative analysis of patient-reported outcomes between TKA and THA while adjusting for patient background. METHODS: A total of 326 primary TKAs and 259 THAs conducted at a single center were assessed using Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores preoperatively and at 3 months, 1 year, and 2 years postoperatively. Notably, TKA patients exhibited advanced age and higher body mass index (BMI) than their THA counterparts. To mitigate the impact of these differences, we employed propensity score-matched data, adjusting for background characteristics such as age, gender, BMI, and diagnosis. RESULTS: THA consistently demonstrated significantly superior WOMAC total, pain, and stiffness scores compared to TKA at 3 months, 1 year, and 2 years postoperatively. Nevertheless, no statistically significant disparity in WOMAC physical function scores was observed between the two groups at 3 months and 1 year postoperatively in the matched data (3 months, p = 0.131; 1 year, p = 0.269). CONCLUSION: In contrast to earlier findings, our analysis of propensity score-matched data revealed no significant differences in WOMAC physical function scores between the TKA and THA groups at 3 months and 1 year postoperatively. The distinctive background factors observed in patients undergoing TKA and THA, notably advanced age and higher BMI, coupled with the delayed improvement timeline in TKA's WOMAC scores compared to that of THA, have the potential to impact patient-reported outcomes. Consequently, clinicians should be mindful of the potential impact of patient background on variations in patient-reported outcome measures following total joint arthroplasty.

Is bone remodelling around fully hydroxyapatite-coated and tapered-wedge stems related to the stem fixation pattern?

PURPOSE: This study aimed to compare bone mineral density (BMD) changes around the femoral component after total hip arthroplasty (THA) in a fully hydroxyapatite-coated stem (CORAIL) and in a tapered-wedge stem (Taperloc complete) and identify predictors of BMD changes. METHODS: This retrospective study compared 43 hips in the CORAIL group and 40 hips in the Taperloc group. The relative changes in BMD at 2 years after THA measured using dual-energy X-ray absorptiometry and the three-dimensional quantified contact states of the stem with the femoral cortical bone were assessed. Predictors of the relative change in the BMD around the proximal part of the stem were examined using multiple regression analysis. RESULTS: The decrease in BMD in Gruen zone 7 was significantly less in the CORAIL group than in the Taperloc group (P = 0.02). In the CORAIL group, the contact area in any zone was not a significant predictor of the relative changes in BMD. The contact area between the Taperloc stem and the femoral cortical bone in zones 2 and 6 was a positive predictor of the relative changes in BMD in zones 1 (P = 0.02 and P = 0.04, respectively) and 2 (P = 0.008 and P = 0.004, respectively). CONCLUSION: The CORAIL stem suppressed the postoperative BMD loss around the stem, irrespective of the contact state. The Taperloc complete stem required contact with the proximal femoral metaphysis to suppress the postoperative BMD loss around the stem.

A new accelerometer-based portable navigation system provides high accuracy of acetabular cup placement in total hip arthroplasty in both the lateral decubitus and supine positions.

INTRODUCTION: No studies have compared the accuracy of acetabular cup placement in total hip arthroplasty (THA) in the supine and lateral decubitus positions using the same portable navigation system. Thus, this study aimed to compare the accuracy of acetabular cup placement using a new accelerometer-based portable navigation system combined with an infrared stereo camera and inertial measurement unit between the supine and lateral decubitus positions. MATERIALS AND METHODS: This retrospective study compared 45 THAs performed in the supine position (supine group) and 44 THAs performed in the lateral decubitus position (lateral group) using the same portable navigation system. The primary outcome was the absolute errors of cup placement angles, defined as the absolute values of the differences between cup radiographic inclination and anteversion angles displayed on the navigation system and those measured on postoperative computed tomography images. RESULTS: No significant difference in the median absolute error of the cup inclination angle (supine group 1.7° [interquartile range 0.8°-3.1°] vs. lateral group 2.1° [interquartile range 1.0°-3.7°]; p = 0.07) was found between the two groups. Similarly, no significant difference in the median absolute error of the anteversion angle (supine group 1.9° [interquartile range 0.8°-3.4°] vs. lateral group 2.1° [interquartile range 0.9°-3.1°]; p = 0.42) was found. CONCLUSION: This new accelerometer-based portable navigation system may provide high accuracy of the cup placement in THA in the lateral decubitus and supine positions.

A double tapered fully hydroxyapatite-coated stem has less contact area to femoral cortical bone than a tapered-wedge stem: a three-dimensional computed tomography-based density mapping analysis.

INTRODUCTION: It is clinically important to analyze the initial contact state between an implant and femoral cortical bone as it affects clinical outcomes, such as stress shielding, stem subsidence, thigh pain, and patient-reported outcomes after total hip arthroplasty. Whether the initial contact state of a double-tapered fully hydroxyapatite (HA)-coated stem is achieved with the preserved cancellous or cortical bone remains to be established. This study aimed to compare the contact area with the femoral cortical bone between a double-tapered fully HA-coated stem (HA group) and a tapered wedge cementless stem (TW group) using three-dimensional computed tomography (3DCT)-based templating software. MATERIALS AND METHODS: Forty-seven total hip arthroplasties in the HA and TW groups each were retrospectively analyzed. The contact area between the implant and femoral cortical bone in the whole stem and at each Gruen zone was measured using density mapping with 3DCT-based templating software. RESULTS: The demographic data were not significantly different between the two groups. The contact area in the whole stem area was lower in the HA group (HA 5.4 ± 1.8% vs. TW 9.0 ± 4.8%, p < 0.01). The HA group had a lower contact area in zone 2 (HA 6.7 ± 6.5% vs. TW 15.6 ± 10.8%, p < 0.01) and zone 6 (HA 1.8 ± 3.5% vs. TW 6.3 ± 3.6%, p < 0.01) than the TW group. The implant type (ß = 0.41, p < 0.01) and stem coronal alignment (ß = - 0.29, p < 0.01) were significant predictors of the contact area in the whole stem area in a multiple regression analysis (adjusted R2 = 0.27, p < 0.01). CONCLUSION: The contact area of the double-tapered fully HA-coated stem was significantly lower than that of the tapered wedge cementless stem.

Mobile-bearing prosthesis suppresses the postoperative rotational mismatch and improves patient-reported outcome measurements better than fixed-bearing prosthesis: rotational analysis by 3D measurement in total knee arthroplasty.

INTRODUCTION: It is preferable to reduce postoperative excessive rotational mismatch between the femur and tibia that causes poor clinical results following total knee arthroplasty (TKA). The aim of this study is to compare postoperative rotational mismatches and clinical outcomes with mobile- and fixed-bearing prostheses. MATERIALS AND METHODS: This study classified 190 TKAs into two groups equally by propensity score matching: mobile-bearing group (n = 95) and fixed-bearing group (n = 95). Computed tomography images of the whole leg were taken at 2 weeks postoperatively. The component alignments, rotational mismatches between the femur and tibia, and rotations among components were measured three-dimensionally. The knee range of motion, New Knee Society Score (KSS) subjective sores, and Forgotten Joint Score (FJS-12) were assessed at the final follow-up. RESULTS: Rotational mismatch between the femur and tibia was significantly less in the mobile- (- 0.8° ± 7.3°) than in the fixed-bearing (3.3° ± 8.5°, p < 0.001) group. New KSS functional activity score was significantly poorer in patients with excessive rotational mismatch (61.3 ± 21.4) than in those without it (49.5 ± 20.6, p = 0.02). Comparing mobile-bearing prosthesis, the use of fixed-bearing prosthesis was a risk factor for postoperative excessive rotational mismatch (odds ratio: 2.32, p = 0.03). CONCLUSION: When compared to a fixed-bearing prosthesis, TKA using a mobile-bearing prosthesis could suppress the postoperative rotational mismatch between the femur and tibia that causes poor subjective functional activity score. However, since this study was conducted for PS-TKA, the results might not be applicable to other models.

The modification of bone cut angle and joint line obliquity did not change the tibiofemoral kinematics and stability of knee joint after total knee arthroplasty.

INTRODUCTION: Previous reports using cadaveric knees and musculoskeletal computer simulation have shown that kinematically aligned (KA) total knee arthroplasty (TKA) provides more natural and physiological tibiofemoral kinematic patterns than mechanically aligned (MA) TKA. These reports suggested that the modification of joint line obliquity improve the knee kinematics. This study aimed to determine whether joint line obliquity change the intraoperative tibiofemoral kinematics in TKA candidates with knee osteoarthritis. METHODS: Thirty consecutive knees with varus osteoarthritis that underwent TKA using a navigation system were evaluated. Two types of trial components were prepared: (1) MA TKA model: component trial in which articulating surface was parallel to the bone cut surface (2) KA TKA model: the femoral component trial, which mimicked the KA TKA method of Dossett et al. was designed 3° valgus and 3° internal rotation to the femoral bone cut surface, and the tibial component trial was designed 3° varus to the tibial bone cut surface. These two trials were set on the same knees during the operation, and the tibiofemoral rotational kinematics and varus-valgus laxity were measured from 0° to 120° of knee flexion using a navigation system. RESULTS: The joint gap was 20 ± 2 mm and 3° ± 1° varus in extension and 20 ± 2 mm and 3° ± 1°varus in flexion. The differences in femoral component rotation between KA TKA and MA TKA were not statistically significant for any knee flexion angle. The differences in varus-valgus laxity between KA TKA and MA TKA were also not statistically significant for any knee flexion angle. CONCLUSION: Although the degree of joint line obliquity varies widely in various KA TKA methods, this study, which mimicked the method of Dossett et al. showed that the modification of joint line obliquity did not change the tibiofemoral kinematics and stability of the knee joint in TKA candidates with knee osteoarthritis.

Eldecalcitol regulates the gene expressions of articular cartilage markers and differentiation markers in chondrocytes.

Vitamin D has been shown to reduce symptoms in patients with osteoarthritis (OA). In a previous study, local administration of eldecalcitol, an active vitamin D3 analog, reduced degenerative changes in articular cartilage in the early phase of experimental OA. However, the target of vitamin D in OA remains unknown. Here, we investigated the effect of eldecalcitol treatment on chondrocytes, which were divided into superficial zone chondrocytes (SZC), deep zone chondrocytes (DZC), and differentiated chondrocytes. SZC and DZC were cultured in monolayer and 3D pellet cultures treated with eldecalcitol. The gene expressions of articular cartilage and chondrocyte differentiation markers were evaluated. Histological analysis of SZC and DZC 3D pellet cultures was performed. The results showed that the articular cartilage markers ETS-related gene (Erg) and lubricin/proteoglycan 4 (PRG4) were significantly increased in SZC, but not in DZC, in the monolayer culture treated with eldecalcitol. The chondrocyte differentiation markers type X collagen and alkaline phosphatase (ALP) were significantly decreased in the DZC pellet culture treated with eldecalcitol. Immunochemical analysis also showed that Erg and lubricin/PRG4 expressions were elevated in the SZC pellet culture treated with eldecalcitol, while type X collagen and ALP expressions were decreased in the DZC pellet culture treated with eldecalcitol. In conclusion, this study showed that eldecalcitol upregulated articular cartilage markers in SZC and suppressed differentiation markers in DZC. Such regulation of chondrocytes by eldecalcitol could be potentially effective against OA progression.

A cemented mobile-bearing total knee prosthesis prevents peri-prosthetic bone mineral density loss around the femoral component: a consecutive follow-up at a mean of 11 years.

PURPOSE: Research has shown that a cemented mobile-bearing component has a favorable effect on the bone mineral density (BMD) of the distal femur at 2 years after total knee arthroplasty (TKA). This study was performed to determine whether the advantage on BMD of a cemented mobile-bearing TKA over a conventional cemented fixed-bearing TKA changes with time. This report is an update of a matched cohort study initiated in 2004 and for which the 2-year results have been published. METHODS: Twenty-eight knees that were treated with a fixed-bearing posterior stabilized (PS) prosthesis and 28 matched knees from a database of 76 knees that were treated with a mobile-bearing PS prosthesis in the same period were investigated. All knees underwent dual-energy X-ray absorptiometry (DEXA) scans around the femoral component preoperatively, 2 weeks postoperatively, 5 years postoperatively, and annually thereafter. Eighteen knees with a cemented mobile-bearing PS prosthesis and 20 knees with a cemented fixed-bearing PS prosthesis were investigated for more than 6 years. The mean follow-up period was 11 years. RESULTS: The range of motion, Knee Society Score, BMD of the lumbar spine, and follow-up period were not significantly different preoperatively and postoperatively in the two groups. In the fixed-bearing group, the BMD of the anterior part of the femoral condyle decreased postoperatively. In the mobile-bearing group, the BMD of the posterior part of the femoral condyle increased postoperatively. The postoperative change in the BMD at 5 years and the latest follow-up period was statistically significant in the two groups. CONCLUSIONS: This DEXA study revealed that a cemented mobile-bearing component had a favorable effect on the BMD of the distal femur after TKA even at a mean of 11 years postoperatively. LEVEL OF EVIDENCE: Therapeutic study, level II, prospective comparative study.

No Difference in Postoperative Knee Flexion and Patient Joint Awareness Between Cruciate-Substituting and Cruciate-Retaining Medial Pivot Total Knee Prostheses: A 10-Year Follow-Up Study.

BACKGROUND: This study aimed to clarify differences in clinical results, including in patients' joint awareness, between cruciate-substituting (CS) and cruciate-retaining (CR) medial pivot total knee arthroplasty (TKA) over a 10-year follow-up. METHODS: A total of 333 TKAs were included in this study. There were 257 cases of CS and 76 cases of CR TKAs. Knee range of motion, Knee Society Score, and radiological outcomes were assessed. The patients' joint awareness was evaluated using the Forgotten Joint Score-12 at the final follow-up. The survival rate with respect to reoperation or revision was analyzed. RESULTS: The mean follow-up period was 10 ± 1.7 years, and the loss to follow-up was 5.4%. All clinical outcomes improved significantly after surgery in both groups (P < .001). Postoperative knee flexion was 118° ± 13° in the CS group and 116° ± 10° in the CR group (P = .10). The mean Forgotten Joint Score-12 scores were 57 ± 27 points in the CS group and 56 ± 28 points in the CR group (P = .59). Ten years after the operation, the survival rates for reoperation were 96.3% in the CS group and 94.2% in the CR group (P = .61), and those for revision were 98.4% and 98.7% in the CS and CR groups, respectively (P = .87). Other postoperative clinical results did not differ between the 2 groups. CONCLUSION: In this 10-year follow-up study, medial pivot TKA, regardless of polyethylene insert type, showed a high survival rate and good patient awareness of the prosthetic joint.

Comparison of postoperative knee flexion and patient satisfaction between newly and conventionally designed medial pivot total knee arthroplasty: a 5-year follow-up matched cohort study.

INTRODUCTION: The medial pivot total knee arthroplasty (TKA) has good patients' satisfaction; however, there is likely the restriction of postoperative knee flexion. The 2nd generation medial pivot TKA prosthesis was designed to improve postoperative knee flexion. This study aimed to compare the clinical outcomes and patient satisfaction between the 2nd generation and 1st generation medial pivot TKA prostheses. MATERIALS AND METHODS: We conducted a retrospective study of 472 consecutive TKAs, performed using either the 2nd generation (EVOLUTION™), having smaller posterior femoral condyle and asymmetrical tibial tray, or 1st generation (ADVANCE™) prosthesis. The use of each system was historically determined. Patient age, sex and body mass index were matched between the two groups, with 157 cases ultimately included in each group. Measured clinical outcomes included: knee range of motion, the Knee Society Score, the rate of re-operation, and radiological parameters. Patient satisfaction was evaluated using the 12-item Forgotten Joint Score (FJS-12). RESULTS: The average follow-up period was 5.0 (3.7-6.3) years for the 2nd generation group and 8.7 (6.1-12.8) years for the 1st generation group (p < 0.01). The postoperative knee flexion range was 127° (80°-140°) for the 2nd generation and 118° (90°-135°) for the 1st generation at final follow-up (p < 0.01). On multivariate regression analysis, use of the 2nd generation prosthesis predicted greater postoperative knee flexion. The average FJS-12 score was 64 (0-100) for the 2nd generation and mean 57 (0-100) for the 1st generation (p < 0.01). Other clinical outcomes were similar between the two groups. CONCLUSIONS: Compared to the 1st generation, the 2nd generation medial pivot prosthesis provides greater postoperative knee flexion and patient satisfaction.

Is medial pivot total knee arthroplasty suitable for patients with valgus knee osteoarthritis?

PURPOSE: Medial pivot total knee arthroplasty (MP-TKA) is characterized by the ball-in-socket medial tibiofemoral articulation to achieve low wear and to reproduce the medial pivot motion similar to that in the normal knee, and there have been reports of favorable long-term postsurgical outcomes. However, most of these cases concerned varus knees, and the outcomes of MP-TKA in valgus knees are unknown. The objective of this study was to investigate the postoperative outcomes in end-stage valgus knee OA patients who underwent MP-TKA, through comparisons with those who underwent TKA using the same prosthesis for varus deformity. METHODS: This retrospective, single-center, cohort study analyzed 171 knees of 121 patients who were divided into two groups (valgus knee group: 15 knees (13 patients), varus knee group: 156 knees (109 patients)). Primary outcome measures included the knee joint range of motion (evaluated preoperatively and at every year postoperatively). Secondary outcomes included operative time, laboratory data, estimated blood loss, clinical outcome measures and adverse events. RESULTS: There were no significant differences in age, sex and body mass index, as well as in the postoperative primary and secondary outcome measures between the two groups. CONCLUSION: The use of MP-TKA featuring ball-in-socket medial tibiofemoral articulation in patients with valgus knee OA showed equally favorable clinical outcomes more than 2 years after surgery, compared to patients with varus knees who received MP-TKA.

Topical co-administration of zoledronate with recombinant human bone morphogenetic protein-2 can induce and maintain bone formation in the bone marrow environment.

BACKGROUND: Bone morphogenetic proteins (BMPs) induce osteogenesis in various environments. However, when BMPs are used alone in the bone marrow environment, the maintenance of new bone formation is difficult owing to vigorous bone resorption. This is because BMPs stimulate the differentiation of not only osteoblast precursor cells but also osteoclast precursor cells. The present study aimed to induce and maintain new bone formation using the topical co-administration of recombinant human BMP-2 (rh-BMP-2) and zoledronate (ZOL) on beta-tricalcium phosphate (ß-TCP) composite. METHODS: ß-TCP columns were impregnated with both rh-BMP-2 (30 µg) and ZOL (5 µg), rh-BMP-2 alone, or ZOL alone, and implanted into the left femur canal of New Zealand white rabbits (n = 56). The implanted ß-TCP columns were harvested and evaluated at 3 and 6 weeks after implantation. These harvested ß-TCP columns were evaluated radiologically using plane radiograph, and histologically using haematoxylin/eosin (H&E) and Masson's trichrome (MT) staining. In addition, micro-computed tomography (CT) was performed for qualitative analysis of bone formation in each group (n = 7). RESULTS: Tissue sections stained with H&E and MT dyes revealed that new bone formation inside the ß-TCP composite was significantly greater in those impregnated with both rh-BMP-2 and ZOL than in those from the other experimental groups at 3 and 6 weeks after implantations (p < 0.05). Micro-CT data also demonstrated that the bone volume and the bone mineral density inside the ß-TCP columns were significantly greater in those impregnated with both rh-BMP-2 and ZOL than in those from the other experimental groups at 3 and 6 weeks after implantations (p < 0.05). CONCLUSIONS: The topical co-administration of both rh-BMP-2 and ZOL on ß-TCP composite promoted and maintained newly formed bone structure in the bone marrow environment.

Four-Millimeter Additional Bone Resection in the Distal Femur Does Not Result in an Equivalent Increase in the Extension Joint Gap in Total Knee Arthroplasty.

BACKGROUND: Additional bone resection in the distal femur is performed to increase the extension joint gap in total knee arthroplasty (TKA). The present study aimed to analyze the relationship between the amount of additional bone resection in the distal femur and the increase in the extension joint gap in TKA. METHODS: Fifty knees undergoing TKA for varus osteoarthritis were evaluated. Two femoral trial component models were prepared: (1) a normal model with 9-mm-thick distal and posterior femoral components and (2) an additional bone resection model with a 5-mm-thick distal femoral component (9 mm to 4 mm) and a 9-mm-thick posterior femoral component, which simulated an additional bone cut in the distal femur of 4 mm. The femoral trial component models were set before implantation, and the extension joint gap was measured using a tensor device that had a shape identical to that of the fixed-bearing tibial insert. RESULTS: The additional bone resection model had a larger joint gap than the normal model (P < .01). The mean extension gap increase in the additional bone resection model was 2 (standard deviation 1) mm, which was less than the thickness of the additional bone resection (4 mm) (P < .01). CONCLUSION: The amount of additional bone resection in the distal femur was not equal to the increase in the extension joint gap. Additional bone resection of 4 mm in the distal femur only increased the extension joint gap by a mean of 2 mm.