A case of 49,XXXYY followed-up from infancy to adulthood with review of literature.

49,XXXYY is an extremely rare sex chromosomal aneuploidy (SCA), with only seven cases reported worldwide to date. Among these cases, only three have been documented into adulthood. Moreover, no cases of 49,XXXYY have been reported in Japan. This SCA has been identified in two scenarios: in vitro fertilization and abortion. Similar to 47,XXY, this aneuploidy is a type of Klinefelter syndrome. Aneuploidy of the X chromosome can lead to various progressive complications due to excess X chromosomes. Herein, we present the case of a Japanese man with 49,XXXYY. He exhibited developmental delays and external genitalia abnormalities since early infancy but was not closely monitored for these symptoms until the age of 3 years old. At that time, a chromosome test revealed his karyotype to be 49,XXXYY. Subsequent examinations were conducted due to various symptoms, including delayed motor development, intellectual disability, facial dysmorphisms, forearm deformities, hip dysplasia, cryptorchidism, micropenis, primary hypogonadism, and essential tremor. Since reaching puberty, he has undergone testosterone replacement therapy for primary hypogonadism, experiencing no complications related to androgen deficiency to date. He has maintained normal lipid and glucose metabolism, as well as bone density, for a prolonged period. There are no other reports on the long-term effects of testosterone treatment for the SCA. Appropriate testosterone replacement therapy is recommended for individuals with 49,XXXYY to prevent complications. This report will contribute to an enhanced understanding of the 49,XXXYY phenotype, aiding in the diagnosis, treatment, and genetic counseling of future cases.

Low Young's Modulus TiNbSn Alloy Locking Plates Accelerate Osteosynthesis in Rabbit Tibiae.

A new beta TiNbSn alloy with a low Young's modulus of approximately 40 GPa has been developed to resolve the stress shielding by Young's modulus divergence. In this study, the efficacy of TiNbSn alloy locking plates on bone repair is compared to that of commercially pure titanium (CP-Ti). The TiNbSn alloy and CP-Ti, which have Young's moduli of 49.1 GPa and 107 GPa, respectively, were compared. Male Japanese white rabbits were anesthetized, and osteotomy and osteosynthesis with locking plates were performed on the right tibia. The bone repair was assessed using micro-computed tomography (CT), histomorphometry, immunohistochemistry, and mechanical testing. Micro-CT, histomorphometry, immunohistochemistry, and mechanical testing were performed four weeks after osteotomy. Six weeks after surgery, micro-CT and mechanical testing were performed. Micro-CT analysis at four weeks after surgery showed that the intramedullary fracture callus in the TiNbSn alloy group had more bone volume and numerous bridging structures compared to the CP-Ti group (CP-Ti vs. TiNbSn alloy, 34.3 ± 13.1 mm3 vs. 61.3 ± 19.6 mm3, p = 0.02; mean ± standard deviation). At four weeks post-osteotomy, the healed tibia showed significantly higher strength in the TiNbSn alloy group compared with CP-Ti (CP-Ti vs. TiNbSn alloy, 81.3 ± 31.2 N vs. 133.7 ± 46.6 N, p = 0.04). TiNbSn alloy locking plates had a more positive impact on bone formation and bone strength restoration than the CP-Ti locking plates during the early phase of bone healing.

How much force is acting on the shoulder joint to create a Hill-Sachs Lesion or reverse Hill-Sachs Lesion?

BACKGROUND: It has not been clarified yet how much force is acting on the shoulder joint to create Hill-Sachs/reverse Hill-Sachs lesions which are commonly observed in patients with anterior or posterior shoulder instability. The purpose of this study was to determine the magnitude of force to create these bony lesions using cadaveric shoulders. METHODS: Fourteen fresh-frozen cadaveric shoulders were used. Compression tests were performed using the universal testing machine. The specimens were randomly divided into two groups. In group A, the posterior humeral head (the bare area and articular cartilage) was first compressed against the anterior glenoid rim to simulate a Hill-Sachs lesion, followed by the anterior humeral head being compressed against the posterior glenoid rim. In group B, the same procedure was repeated in the reverse order. X-ray microcomputed tomography (microCT) was also performed. RESULTS: The maximum compression force to create a Hill-Sachs lesion was 771 ± 214 N (mean ± SD) on the articular cartilage of the posterior humeral head, which was significantly greater than the force of 447 ± 215 N to create it on the bare area (P = 0.0086). Regarding the reverse Hill-Sachs lesions, the maximum compression force was 840 ± 198 N when it was created on the articular cartilage of the anterior humeral head, which was significantly greater than the force of 471 ± 100 N when it was created at the footprint of the subscapularis tendon (P = 0.0238). MicroCT showed multiple breakage of the trabecular bone. CONCLUSION: A force to create a Hill-Sachs lesion or a reverse Hill-Sachs lesion was significantly greater when it was created on the humeral articular cartilage than at the non-cartilage area. Also, the force to create a reverse Hill-Sachs lesion was significantly greater than the one to create a Hill-Sachs lesion.

ß-type TiNbSn Alloy Plates With Low Young Modulus Accelerates Osteosynthesis in Rabbit Tibiae.

BACKGROUND: Ti6Al4V alloy, which is commonly used for biomedical applications, has a Young modulus (110 GPa) that is higher than that of human cortical bone (11 to 20 GPa). Using an implant with a material with a low Young modulus that enhances load sharing by the bone even more than those made of Ti6Al4V could be beneficial for bone healing and further reduce the potential for stress shielding. A new ß-type TiNbSn alloy has a low Young modulus of approximately 40 to 49 GPa. However, whether the new titanium alloy with a lower Young modulus is advantageous in terms of fracture healing has not been assessed, and a small-animal model seems a reasonable first step in its assessment. QUESTIONS/PURPOSES: To assess the impact of a TiNbSn alloy plate with a lower Young modulus compared with a Ti6Al4V alloy plate on fracture healing, we evaluated: (1) bony bridging and callus volume, (2) new bone formation and remaining cartilage tissue, (3) osteoblast activity in the callus, and (4) mechanical strength and stiffness of the callus in bending. METHODS: Fracture plates manufactured from TiNbSn and Ti6Al4V alloys, which have Young moduli of 49 GPa and 110 GPa, respectively, were compared. The main reason for using rabbits was the high reliability of the three-point bending mechanical test of the rabbit tibia. Forty-two male Japanese white rabbits weighing 2.8 to 3.4 kg were anesthetized. A 5-cm skin incision was made on the medial side in the mid-diaphysis of the right tibia. Eight-hole plates were used, which were 42 mm long, 5 mm wide, and 1.2 mm thick. Plate fixation was performed using three proximal and three distal screws. After the plate was installed, an osteotomy was performed using a 1-mm-wide wire saw to create a standardized tibial transverse osteotomy model with a 1-mm gap. Bone healing was quantitatively assessed by two nonblinded observers using micro-CT (bony bridging and callus volume), histomorphometry (new bone formation and remaining cartilage tissue), immunohistochemistry (osteoblast activity), and mechanical testing (mechanical strength and stiffness in bending). Measurements on nondemineralized specimens were descriptive statistics due to their small number. Four weeks after osteotomy and fixation, 30 rabbits were euthanized to undergo micro-CT and subsequent mechanical testing (n = 12), histomorphometry and immunohistochemistry with demineralized specimens (n = 12), and histomorphometry with a nondemineralized specimen (n = 6). Eight weeks postoperatively, 12 rabbits were euthanized for micro-CT and subsequent mechanical testing. RESULTS: Intramedullary fracture calluses treated with TiNbSn alloy plates had larger bone volumes and more numerous bridging structures than those treated with Ti6Al4V alloy plates at 4 weeks after osteotomy (Ti6Al4V alloy versus TiNbSn alloy: 30 ± 7 mm 3 versus 52 ± 14 mm 3 , mean difference 22 [95% CI 9 to 37]; p = 0.005; ICC 0.98 [95% CI 0.95 to 0.99]). Histologic assessments demonstrated there was greater new bone formation (total callus: Ti6Al4V versus TiNbSn: 16 ± 4 mm 2 versus 24 ± 7 mm 2 , mean difference 8 [95% CI 1 to 16]; p = 0.04; ICC 0.98 [95% CI 0.93 to 0.99]; intramedullary callus: Ti6Al4V versus TiNbSn: 6 ± 4 mm 2 versus 13 ± 5 mm 2 , mean difference 7 [95% CI 1 to 13]; p = 0.02; ICC 0.98 [95% CI 0.95 to 0.99]) and a higher number of osteocalcin-positive cells (Ti6Al4V alloy versus TiNbSn alloy: 1397 ± 197 cells/mm 2 versus 2044 ± 183 cells/mm 2 , mean difference 647 [95% CI 402 to 892]; p < 0.001; ICC 0.98 [95% CI 0.95 to 0.99]) in the TiNbSn alloy group than in the Ti6Al4V alloy group. At 4 weeks after osteotomy, both bone strength and stiffness of the healed bone in the TiNbSn alloy group were higher than those in the Ti6Al4V alloy group (maximum load: Ti6Al4V alloy versus TiNbSn alloy: 83 ± 30 N versus 127 ± 26 N; mean difference 44 [95% CI 8 to 80]; p = 0.02; stiffness: Ti6Al4V alloy versus TiNbSn alloy: 92 ± 43 N/mm versus 165 ± 63 N/mm; mean difference 73 [95% CI 4 to 143]; p = 0.047). Eight weeks after osteotomy, no between-group differences were observed in the strength and stiffness of the healed bone. CONCLUSION: The results of this study indicate that TiNbSn alloy plate with a lower Young modulus resulted in improved bone formation and stiffer callus during the early phase (4 weeks after surgery) but not the later phase (8 weeks after surgery) of bone healing. CLINICAL RELEVANCE: An overly stiff plate may impair callus formation and bone healing. The TiNbSn alloy plate with a low Young modulus improves the early formation of new bone and stiff callus at the osteotomy site compared with the Ti6Al4V alloy plate in the healing process, which may promote bone repair. TiNbSn alloy may be a promising biomaterial for fracture treatment devices. Further research to address concerns about the strength of TiNbSn alloy plates, such as fatigue life and plate fracture, will be necessary for clinical applications, including mechanical tests to verify fatigue life and validation in larger animals with greater body weight.

Acceleration of Fracture Healing in Mouse Tibiae Using Intramedullary Nails Composed of ß-Type TiNbSn Alloy with Low Young's Modulus.

The optimal Young's modulus of material of orthopedic devices for fracture treatment is still unknown. The purpose of present study was to evaluate the impacts of intramedullary nails composed of a titanium alloy with low Young's modulus, on accelerating fracture healing compared with stainless steel with high Young's modulus. A ß-type TiNbSn alloy with a low Young's modulus close to that of human cortical bone was developed for clinical application. TiNbSn alloy with a Young's modulus of 45 GPa and stainless steel with a Young's modulus of 205 GPa were compared, with respect to the impacts on fracture healing. Fracture and fixation using intramedullary nail were performed on the right tibiae of C57BL/6 mice. The assessment of bone healing was performed via micro-computed tomography, histomorphometry, and quantitative reverse transcription polymerase chain reaction. In micro-computed tomography, larger bone volumes were observed in the fracture callus treated with TiNbSn alloy in comparison with those treated with stainless steel. Histological assessments confirmed accelerated cartilage absorption and new bone formation in the TiNbSn alloy group compared with the stainless steel group. The expression of Col1a1, Runx2, Dkk1, and Acp5 was higher in the TiNbSn alloy group, while that of Col2a1 and Col10a1 was lower in the late phase. The present study demonstrated that the fixation by intramedullary nails with TiNbSn alloy offered an accelerated fracture healing with promotion of bone formation via increased Runx2 expression. TiNbSn alloy might be a promising material for fracture treatment devices.

Obesity is a risk factor for osteoarthritis progression and spontaneous osteoporosis is a risk for the development of spontaneous osteonecrosis in patients with medial meniscus posterior root tear.

BACKGROUND: Obesity is a representative risk factor for osteoarthritis (OA). The relationship between osteoporosis and executed osteonecrosis has been reported. The primary aim of this study was to determine the influence of obesity and osteoporosis on disease progression in patients with medial meniscus posterior root tear (MMPRT). METHODS: We included 41 knees with MMPRT in this study. MMPRT was diagnosed based on the presence of both a meniscus ghost sign and a vertical linear defect on MRI. OA progression and development of osteonecrosis were evaluated using plain radiographs obtained at the initial visit and the final follow-up. The follow-up period for all knees was 30 ± 8 (mean ± standard deviation) months. Patients' physical attributes were assessed at initial visits; these attributes included body mass index (BMI) and the clinical risk for osteoporotic fracture, as determined by the World Health Organization fracture risk assessment tool (FRAX). Patients with a BMI ≥25 kg/m2 were classified in the obesity group and those with a BMI <25 kg/m2 in the control group. Patients with a FRAX score of ≥10% were classified in the high FRAX group and those with a FRAX score of <10% in the low FRAX group. RESULTS: OA progression evaluated by Kellgren-Lawrence grading scale was observed in 75% patients in the obesity group (1 grade in 38%, 2 grades in 31%, and 3 grades in 6%) and 58% in the control group (1 grade in 58%). Patients in the obesity group showed significantly greater OA progression. Spontaneous osteonecrosis was observed in no knees at the initial visit and six knees at the final follow-up. All six lesions were observed in the high FRAX group, which was statistically significant. CONCLUSIONS: OA progression and development of osteonecrosis were the two representative deterioration patterns in patients with MMPRT. High BMI was related with OA progression, and FRAX score of ≥10% with the development of osteonecrosis.

Reference values for the locomotive syndrome risk test quantifying mobility of 8681 adults aged 20-89 years: A cross-sectional nationwide study in Japan.

BACKGROUND: The locomotive syndrome risk test was developed to quantify the decrease in mobility among adults, which could eventually lead to disability. The purpose of this study was to establish reference values for the locomotive syndrome risk test for adults and investigate the influence of age and sex. METHODS: We analyzed 8681 independent community dwellers (3607 men, 5074 women). Data pertaining to locomotive syndrome risk test (the two-step test, the stand-up test, and the 25-question geriatric locomotive function scale [GLFS-25]) scores were collected from seven administrative areas of Japan. RESULTS: The reference values of the three test scores were generated and all three test scores gradually decreased among young-to-middle-aged individuals and rapidly decreased in individuals aged over 60 years. The stand-up test score began decreasing significantly from the age of 30 years. The trajectories of decrease in the two-step test score with age was slightly different between men and women especially among the middle-aged individuals. The two physical test scores were more sensitive to aging than the self-reported test score. CONCLUSION: The reference values generated in this study could be employed to determine whether an individual has mobility comparable to independent community dwellers of the same age and sex.

Meniscal tear morphology independently affects pain relief following arthroscopic partial meniscectomy in middle-aged patients.

PURPOSE: To analyze the influence of meniscal tear pattern on clinical outcomes following arthroscopic partial meniscectomy in middle-aged patients with medial meniscal tears. METHODS: A total of 123 patients (130 knees) aged ≥ 50 years who underwent arthroscopic partial meniscectomy for medial meniscal tears were evaluated. Inclusion criteria were none to moderate medial knee osteoarthritis [Kellgren-Lawrence (KL) grade ≤ 3] and a minimum of 2-year follow-up (median 4.6 years; range 2.1-8.0 years). Meniscal tears observed during arthroscopic examination were classified into six types: radial tear of the middle segment, posterior root tear, horizontal tear of the posterior segment, flap tear, minor tear, and complex tear. Postoperative outcomes were classified into effective (group 1) and non-effective (group 2) according to the pain relief administered 1 month postoperatively and at the final follow-up. Demographic variables, KL grade, type of meniscal tear, and postoperative follow-up period were evaluated. RESULTS: Forty knees (38%) were classified into group 1. Of the six types of tears, radial tear of the middle segment [odds ratio (OR) 4.1, 95% confidence interval (CI) 1.1-20.9] and flap tear (OR 12.9, 95% CI 1.8-140.7) were significant predictors of good outcome on multivariate logistic regression analysis. CONCLUSIONS: In middle-aged patients with medial meniscal tears, radial tear of the middle segment was independently associated with less pain following arthroscopic meniscectomy. Arthroscopic partial meniscectomy may be indicated in patients with radial tear if conservative treatment fails. LEVEL OF EVIDENCE: Case-control study, Level III.

Quality of life after staged bilateral total knee arthroplasty: a minimum five-year follow-up study of seventy-eight patients.

PURPOSE: Although many studies have been performed to evaluate the quality of life (QOL) and patient satisfaction after total knee arthroplasty (TKA), almost all evaluations were performed in patients after unilateral TKA or in patients after mixed unilateral and bilateral TKA. Accordingly, this study aimed to evaluate QOL after staged bilateral TKA. METHODS: A total of 78 patients who underwent staged bilateral TKA for varus knee osteoarthritis were included in this study. All patients had longitudinal follow-up evaluations for at least five years. QOL was assessed by the Japanese Knee Osteoarthritis Measure (JKOM), a disease-specific and patient-derived QOL measure for Japanese patients. Conventional objective outcome scales, including the Knee Society Score and the Timed Up and Go test, were also assessed. In addition, QOL and objective outcomes were compared between the younger (≤ 80 years, average 75.8 years) and older (> 80 years, average 84.7 years) age groups at the final follow-up. RESULTS: Improvements in both JKOM and objective outcomes reached a plateau one year after staged bilateral TKA. Improvements were prolonged for more than five years. There were no statistically significant differences in JKOM or objective outcomes between the younger and older age groups, despite an 8.9-year difference in the average age. CONCLUSIONS: This was the first longitudinal study to evaluate QOL and objective outcomes after staged bilateral TKA for a period of at least five years. Improvements in QOL and objective outcomes reached a plateau one year after staged bilateral TKA and were prolonged for more than five years. No significant differences were observed in outcome scores between the younger and older age groups.

The effect of morphine added to periarticular multimodal drug injection or spinal anesthesia on pain management and functional recovery after total knee arthroplasty.

BACKGROUND: The efficacy of morphine added to periarticular multimodal drug injection (PMDI) for pain management after total knee arthroplasty (TKA) is controversial. Adding morphine to spinal anesthesia has reportedly improved pain relief for the first 24 h. We examined the effect of morphine added to PMDI or spinal anesthesia on pain management and functional recovery after TKA. METHODS: A total of 97 patients were randomized into three groups: in Group A (34 patients), 10 mg morphine was added to PMDI; Group B (31 patients), 0.1 mg morphine was added to spinal anesthesia; and Group C (32 patients), morphine was added to neither the PMDI nor spinal anesthetic. To evaluate the efficacy of added morphine for pain management, we assessed rest pain, the number of times analgesics were used, and the time period until the first analgesic use. The adverse effects of morphine were assessed by counting the numbers of times vomiting occurred and antiemetics were used. Functional recovery was evaluated by recording the range of motion of the knee and the date of ability to walk. RESULTS: Rest pain was the least in Group B at 6 and 12 h after operation. The number of times analgesics were used was the least in Group B. The time period until the first analgesic use was the longest in Group B. The number of vomiting episodes was the least in Group C. The number of times antiemetics were used was higher in Group A than in Group C. There were no significant differences in the range of motion and date of ability to walk among the three groups. CONCLUSIONS: The efficacy of morphine added to PMDI was limited, and that of morphine added to spinal anesthesia disappeared within 20 h postoperatively. Adding morphine to PMDI or spinal anesthesia did not improve functional recovery and caused some adverse effects.

Bone mineral density of postmenopausal women with rheumatoid arthritis depends on disease duration regardless of treatment.

The aim of this study was to determine the associations of disease activity and disease duration with the bone mineral density (BMD) in rheumatoid arthritis (RA) patients. We also evaluated the associations of biological drugs with bone loss. A total of 138 postmenopausal RA patients were retrospectively assessed to identify the associations of disease activity, disease duration, and biological drug use with BMD. We assessed the associations of disease duration, a C-reactive protein based disease activity score in 28 joints (DAS28), simplified disease activity index, clinical disease activity index, health assessment questionnaire scores, and the use of biological drugs with the lumbar spine, total hip, and femoral neck BMDs using univariate and multivariate linear regression analyses in bisphosphonate treatment and non-bisphosphonate treatment groups at 1 year of follow-up. The multivariate linear regression analyses showed that disease duration was significantly related to the BMD of the femoral neck and total hip regardless of bisphosphonate treatment. The use of biological drugs was not significantly associated with BMD. Hip BMD in postmenopausal women with RA depends on the disease duration regardless of bisphosphonate use. Biological drugs for RA treatment were not negatively associated with general bone loss.

Evaluation of the size and position of the insertion of the anterior medial meniscus root in varus osteoarthritic knees.

PURPOSE: Recent studies have suggested radial displacement of the medial meniscus as a cause of varus knee osteoarthritis (OA). Two anatomical studies reported that such displacement may be associated with anterior insertion of the medial meniscus anterior horn. It was aimed to evaluate the location and area of this insertion in patients with advanced knee OA. METHODS: Medial meniscus anterior horn insertions were classified into four types, as described in a previously reported classification during 225 total knee arthroplasty (TKA) in 184 patients. The incidence rates of insertion type were compared with previously reported rates in nearly normal or non-arthritic knees. The insertion surface area was also measured during 158 TKAs. RESULTS: Of the 225 knees, 82 (36.4 %), 93 (41.3 %), 35 (15.6 %), and 15 (6.7 %) were classified as I, II, III, and IV, respectively. An anteriorly inserted anterior horn was not more frequent in advanced varus OA knees than in previously reported nearly normal or non-arthritic knees. The insertion surface areas were 57.5 ± 18.9, 56.1 ± 16.0, and 56.4 ± 14.4 mm2 for types I, II, and III, respectively; these areas did not differ significantly. CONCLUSION: Since the incidence of an anteriorly inserted medial meniscus anterior horn was not higher in advanced varus OA knees than in normal or non-arthritic knees, an anteriorly inserted anterior horn may have little or no effect on the aetiology of varus OA knees. This study provides some information for clarifying the aetiology of knee OA. LEVEL OF EVIDENCE: IV.

Femoral footprint of the popliteus tendon may be at the risk of damage during total knee arthroplasty.

PURPOSE: The present study focused on the prevalence of incidental excision of the femoral footprint of the popliteus tendon during total knee arthroplasty and its associated risk factors. METHODS: A total of 275 knee arthroplasties were performed for 226 patients with varus knee osteoarthritis. The status of the femoral footprint of the popliteus tendon was intraoperatively evaluated and classified into three groups (preserved, partially excised, and completely excised), and the prevalence of the excision was identified. Femoral component size, the thickness of the resected distal femoral condyle, and preoperative patient demographic data were compared for the three groups. Ordinal logistic regression analysis was performed to reveal risk factors associated with the excision. RESULTS: The femoral footprint of the popliteus tendon was preserved in 132 knees (48.0 %), partially excised in 94 knees (34.2 %) and completely excised in 49 knees (17.8 %). The ordinal logistic regression analysis revealed thicker resection of the distal femoral condyle (p < 0.0001) and shorter body height (p = 0.0266) to be the independent risk factors for the excision. CONCLUSIONS: The incidental partial or complete excision of the femoral footprint of the popliteus tendon was identified in approximately half of the evaluated knees. Thicker resection of the distal femoral condyle and shorter body height were the most significant risk factors for the excision. LEVEL OF EVIDENCE: Case-control study, Level III.

Preliminary results of managing large medial tibial defects in primary total knee arthroplasty: autogenous morcellised bone graft.

PURPOSE: This study reports a case series of 44 primary total knee arthroplasties (TKAs) using autogenous morcellised bone grafting for large (≥10-mm-deep) medial tibial defects, which are generally repaired using metal augmentation. The bone-grafting technique is described in detail and the radiological outcomes are presented. METHODS: A total of 44 TKAs were followed up for a mean period of 58 months (range 24-139 months). Multiple drill holes were made in the sclerotic floor of the defect, followed by the impaction of morcellised cancellous bone grafts to fill the defects. Tibial components were fixed using the cemented or noncemented technique and no internal fixation devices were used. Stem extension of the tibial component was only used in one TKA. RESULTS: Radiograms revealed that the grafted bone was completely incorporated into the host bone within one year post-operatively. No grafted bone absorption or collapse was detected. A clear zone between the tibial component and grafted bone was observed in six knees, but it did not become enlarged thereafter. CONCLUSIONS: The presented technique provided favourable radiological outcomes and had several advantages: (1) it enables preservation of as much bone as possible for future revision surgery; (2) it is cost effective and simple because metal augments, internal fixation devices and stem extension are not needed; (3) it can be used in the same manner any defect to a depth ≥3 mm. Thus, this is an acceptable and reproducible alternative technique.

Identification of a progenitor cell population destined to form fracture fibrocartilage callus in Dickkopf-related protein 3-green fluorescent protein reporter mice.

Fracture healing is a complex biological process involving the proliferation of mesenchymal progenitor cells, and chondrogenic, osteogenic, and angiogenic differentiation. The mechanisms underlying the proliferation and differentiation of mesenchymal progenitor cells remain unclear. Here, we demonstrate Dickkopf-related protein 3 (Dkk3) expression in periosteal cells using Dkk3-green fluorescent protein reporter mice. We found that proliferation of mesenchymal progenitor cells began in the periosteum, involving Dkk3-positive cell proliferation near the fracture site. In addition, Dkk3 was expressed in fibrocartilage cells together with smooth muscle α-actin and Col3.6 in the early phase of fracture healing as a cell marker of fibrocartilage cells. Dkk3 was not expressed in mature chondrogenic cells or osteogenic cells. Transient expression of Dkk3 disappeared in the late phase of fracture healing, except in the superficial periosteal area of fracture callus. The Dkk3 expression pattern differed in newly formed type IV collagen positive blood vessels and the related avascular tissue. This is the first report that shows Dkk3 expression in the periosteum at a resting state and in fibrocartilage cells during the fracture healing process, which was associated with smooth muscle α-actin and Col3.6 expression in mesenchymal progenitor cells. These fluorescent mesenchymal lineage cells may be useful for future studies to better understand fracture healing.

Comparison of intraoperative anthropometric measurements of the proximal tibia and tibial component in total knee arthroplasty.

BACKGROUND: Precise matching of the tibial component and resected bony surfaces and proper rotational implanting of the tibial component are crucial for successful total knee arthroplasty. We aimed to analyze the exact anthropometric proximal tibial data of Japanese patients undergoing total knee arthroplasty and correlate the measurements with the dimensions of current total knee arthroplasty systems. METHODS: A total of 703 knees in 566 Japanese patients who underwent total knee arthroplasty for osteoarthritis were included. The bone resection in the proximal tibia was performed perpendicular to the tibial axis in the frontal plane. Measurements of the proximal tibia were intraoperatively obtained after proximal tibial preparation. RESULTS: There were significant positive correlations between the lateral anteroposterior and medial anteroposterior and mediolateral dimensions. A progressive decrease in the mediolateral/lateral anteroposterior ratio with an increasing lateral anteroposterior dimension or the mediolateral/anteroposterior ratio with an increasing anteroposterior dimension was observed. The lateral anteroposterior dimension was smaller than the medial anteroposterior dimension by a mean of 4.8 ± 2.0 mm. The proximal tibia exhibited asymmetry between the lateral and medial plateaus. A comparison of the morphological data and dimensions of the implants, one of which was a symmetric tibial component (NexGen) and the others were asymmetric (Genesis II and Persona), indicated that an asymmetric tibial component could be beneficial to maximize tibial plateau coverage. CONCLUSIONS: This study provided important reference data for designing a proper tibial component for Japanese people. The proximal tibial cut surface was asymmetric. There was wide dispersion in the lateral anteroposterior, medial anteroposterior, and mediolateral dimensions depending on the patient. Our data showed that the tibial components of the Genesis II and Persona rather than that of the NexGen may be preferable for Japanese people because of their asymmetric design.

Medial meniscus tear morphology and related clinical symptoms in patients with medial knee osteoarthritis.

PURPOSE: The objective of this study was to examine the association between clinical symptoms and arthroscopic meniscal findings in patients with early to moderate medial knee osteoarthritis. METHODS: One hundred and four patients (110 knees) were selected from a group of 132 patients (140 knees) aged ≥50 years who underwent arthroscopic surgery for medial meniscal tears. Inclusion criteria were as follows: (a) medial knee osteoarthritis and (b) simple medial meniscal tears extending to ≥1/4 of the meniscal margin. Subjective symptoms, location and nature of the pain, as well as the physical findings observed during initial assessment were evaluated using a standardized assessment chart. The relationship between arthroscopic meniscal findings and clinical symptoms was then analysed. RESULTS: Isolated meniscal tears were classified into four types: radial tear of the middle segment; posterior root tear; horizontal tear of the posterior segment; and flap tear. The following symptoms were reported at significantly higher frequencies: pain on standing and a catching sensation in patients with flap tears; pain on walking and nocturnal pain on rolling over in bed in patients with radial tears of the middle segment; and popliteal pain in patients with posterior root tears. CONCLUSIONS: This study demonstrates a relationship between the type of medial meniscal tear and characteristic clinical symptoms reported by patients with medial knee osteoarthritis. These results suggest that clinical symptoms in patients with osteoarthritis of the knee may be caused by meniscal tears. This evidence may help to better inform patients and surgeons regarding choice of treatment. LEVEL OF EVIDENCE: Case control study, Level III.

Potential risk of excising the femoral insertion of the popliteus tendon during primary total knee arthroplasty: a biometric study.

BACKGROUND: During total knee arthroplasty (TKA), excision of the popliteus tendon leads to extensive static gaps and reduced mobility. The purpose of this study was to determine the positional relationship between the femoral insertion of the popliteus tendon and the bone cutting lines of various TKA systems. METHODS: This study included 21 cadaveric right femurs presenting no macroscopic deformity. The lateral image of the femur and the template of the femoral component were overlaid to determine the preservation/excision of the popliteus tendon insertion. TKA systems used were Genesis II, NexGen, low contact stress (LCS), PFC Σ, Scorpio, and Vanguard. The knees in which the insertion was preserved in all implants or excised in at least one implant were classified into intact or the high-risk groups, respectively. RESULTS: The popliteus tendon was preserved in all specimens with the LCS system. In contrast, the popliteus tendon insertion was excised in ≥1/3 of the specimens with the other systems. The anteroposterior diameter was significantly larger in the intact group than that in the high-risk group (58.1 ± 4.5 mm vs. 53.7 ± 2.7 mm; p = 0.018). The high-risk group included more knees from female cadavers than the intact group (70 vs. 9 %; p = 0.008). CONCLUSION: During primary TKA, the femoral insertion of the popliteus tendon could be inevitably excised, regardless of technical problems. We demonstrate that the unique design of the LCS system preserves the popliteus tendon insertion. In addition, small knees and females may be risk factors for excision of the insertion.