Medial proximal tibial angle at the posterior tibial plateau represents the pre-arthritic constitutional medial proximal tibial angle in anterior cruciate ligament-intact, advanced osteoarthritis of the knee.

PURPOSE: In kinematically aligned total knee arthroplasty (TKA), it is necessary to infer the pre-arthritic constitutional medial proximal tibial angle (MPTA) in advanced osteoarthritis (OA) of the knee with bone loss. The aim of this study was to investigate whether MPTA at the posterior tibial plateau represents the pre-arthritic constitutional MPTA in anterior cruciate ligament (ACL)-intact, advanced OA knees. It was hypothesized that MPTA at the posterior tibial plateau represents the pre-arthritic constitutional MPTA of ACL-intact, advanced knee OA. METHODS: One hundred varus, anterior cruciate ligament (ACL)-intact, advanced OA knees were analysed. The hip-knee-ankle (HKA) angle and MPTA were assessed on computed radiography (CR) and MPTAs at the anterior, middle, and posterior part of the tibial plateau were assessed on computed tomography (CT) images. The association between these parameters was also analysed. RESULTS: CR images showed an HKA angle of 172.4 ± 4.1° and MPTA of 84.3 ± 2.5°. CT images showed different MPTAs in the three regions, ranging from 83.9 ± 2.4° to 85.9 ± 2.8°. The middle MPTA was the lowest at 83.9 ± 2.4°. HKA angle correlated with the middle MPTA (r = 0.3355, 95% confidence interval [CI] 0.1489-0.4991, p = 0.0006) and ΔMPTA (Middle-Posterior) (r = 0.5128, 95% CI 0.3518-0.6443, p < 0.0001). CONCLUSION: The MPTA at the posterior tibial plateau represents the pre-arthritic constitutional MPTA in ACL-intact, advanced OA knees. LEVEL OF EVIDENCE: III, retrospective cohort study.

Fracture of the tibial tubercle does not affect clinical outcomes in medial opening wedge high tibial osteotomy with distal tibial tubercle osteotomy.

PURPOSE: To investigate whether tibial tubercle fracture affected clinical outcomes and bony union in medial opening wedge high tibial osteotomy with distal tibial tubercle osteotomy (DTO) and to determine the anatomical risk factors for tibial tubercle fracture. MATERIALS AND METHODS: All patients who underwent DTO were retrospectively reviewed, and 104 successive patients were included. The Knee Society Score and complications including tibial tubercle fracture were recorded. On radiographs and computed tomography scans, the length, thickness, width, height, and bony union of the osteotomized tibial tubercle and the posterior tibial slope were statistically analysed. RESULTS: Fracture of the tibial tubercle occurred intraoperatively in 11 patients (10.6%) and in the postoperative period in 1 (1.0%). The case of postoperative fracture showed non-union. There was no significant difference in the Knee Society Score between the non-fracture and fracture groups. There were significant differences in the posterior tibial slope and the height of the tibial tubercle between the groups (p < 0.0001 for each comparison). The logistic regression analysis showed that the height of the tibial tubercle was associated with a higher risk of the fracture of the tibial tubercle (p < 0.01; OR, 1.548; 95% CI, 1.149-2.085). However, there were no significant differences in the bony union rate of the tibial tubercle at 6 months after surgery between the groups. CONCLUSIONS: Tibial tubercle fracture did not affect the clinical outcome and bony union in spite of the relatively high occurrence rate. Anatomical risk factors for the fractures was a lower tibial tubercle position. LEVEL OF EVIDENCE: Level IV.

Total hip arthroplasty using a three-dimensional porous titanium acetabular cup: an examination of micromotion using subject-specific finite element analysis.

BACKGROUND: We investigated the mid-term clinical and radiological results of total hip arthroplasty (THA) using a three-dimensional (3D) porous titanium cup and analyzed the micromotion at the interface of the cup using subject-specific finite element (FE) analysis. METHODS: We evaluated 73 hips of 65 patients (6 men and 59 women; mean age at the time of surgery, 62.2 years; range, 45-86 years) who had undergone THA using a 3D porous titanium cup. Clinical evaluations were performed using the Japanese Orthopaedic Association (JOA) hip score system. We assessed the fixation of the acetabular component based on the presence of radiolucent lines and cup migration using anteroposterior radiographs. Subject-specific FE models were constructed from computed tomography data. RESULTS: The JOA score improved from a preoperative mean of 52.2 (range, 23-82) to a mean of 87.8 (range, 71-100) at the final follow-up. None of the patients underwent revisions during the follow-up period. Radiolucent lines were observed in 26 cases (35.6%) and frequently appeared at DeLee and Charnley Zone 3. Following the FE analysis, the micromotion at DeLee and Charnley Zone 3 was significantly larger than that at Zone 2. Furthermore, micromotion was large in the groups in which radiolucent lines appeared at Zone 3. CONCLUSIONS: The mid-term clinical outcome of THA using a 3D porous titanium cup was excellent. However, radiolucent lines frequently appeared at DeLee and Charnley Zone 3. FE analysis indicated that micromotion was large at the same site, strongly suggesting that it contributes to the emergence of radiolucent lines. The 3D porous titanium cups are useful in THA, and with improvements focused on micromotion, we anticipate better long-term outcomes.

Natural History and Characteristics of Hand Exostoses in Multiple Hereditary Exostoses.

PURPOSE: Multiple hereditary exostoses (MHEs) comprise a rare skeletal disorder. This study aimed to elucidate the natural history and characteristics of hand exostoses by focusing on their progression or regression and their association with shortening and angular deformation of the finger bones. METHODS: Of 60 MHE patients who presented to our hospital between 2005 and 2019, 32 patients (62 hands) who underwent hand x-ray examinations were included in a study of initial presentation. Among them, 15 patients (30 hands) who underwent consecutive x-ray examinations before epiphyseal closure were included in a subsequent follow-up study (follow-up period, 6.9 years). We investigated the incidence and common location of hand involvement by exostoses during the initial examination study. We further investigated the progression or regression of hand exostoses and the influence of hand exostoses on longitudinal bone growth and the angular deformation of finger bones during the follow-up study. RESULTS: In the initial study, we observed exostoses in 30 (60 hands) of 32 (62 hands) patients. The average number of exostoses per hand was 5.2. Exostoses developed more frequently in the middle and ring proximal phalanges and the fifth metacarpal. In the follow-up study, 3.1 exostoses per hand spontaneously regressed and 2.9 exostoses per hand occurred de novo with growth. Progression of exostoses was mainly observed by approximately age 15 years; thereafter, spontaneous regression became dominant. Regression of exostoses was frequently observed in metacarpals, whereas de novo exostoses frequently occurred in phalangeal bones, particularly in distal phalanges. Growth plate involvement by exostoses did not influence the longitudinal growth of finger bones, but it increased their angulation. CONCLUSIONS: The hand is a common location of exostoses development for MHE patients. Although some exostoses in the hands regress with skeletal maturity, hand involvement by exostoses can result in angular deformity. TYPE OF STUDY/LEVEL OF EVIDENCE: Diagnostic IV.

Correlation between mutated genes and forearm deformity in patients with multiple osteochondroma.

BACKGROUNDS: Exostosin-1 (EXT1) and exostosin-2 (EXT2) cause multiple osteochondromas (MO). In this study, we investigated the correlation between forearm deformity and mutant EXTs in Japanese families with MO. METHODS: We evaluated 112 patients in 71 families with MO. Genomic DNA was isolated from peripheral blood leucocytes. Of these, 28 patients were selected and underwent radiography for their forearms since they had gross forearm deformities. We measured the radial articular angle (RAA), ulna variance (UV), carpal slip (CS), and percentage of radial bowing (%RB) to compare between patients with mutant EXT1 or EXT2 and those with missense or other mutations using Student's t-test. RESULTS: Twenty-two (78.6%) and 6 (11.4%) out of 28 patients had mutations in EXT1 and EXT2, respectively. Nine (32.1%) and 19 (67.9%) of the 28 patients had missense and other mutations, respectively. The mean age of patients with EXT1 and EXT2 were 25.9 ± 20.3 and 33.5 ± 25.4 years, respectively and those with missense mutation and other mutations were 28.7 ± 27.0 and 24.6 ± 17.0 years, respectively. There were no significant differences in RAA, UV, and RB between patients harbouring mutant EXT1 or EXT2 (RAA, 40.1 ± 8.7 and 31.5 ± 13.9°; UV, -2.7 ± 5.7 and -3.1 ± 3.7 mm; %RB, 8.6 ± 1.5 and 8.3 ± 2.0%). CS was significantly greater in patients with mutant EXT1 than that in those with mutant EXT2 (EXT1, 44.1 ± 16.8%; EXT2, 18.6 ± 14.0%). There were no significant differences in RAA, UV, CS and %RB between patients with missense and other mutations. CONCLUSIONS: Patients with mutant EXT1 displayed greater CS than patients with mutant EXT2, indicating that patients with MO harbouring EXT1 mutations sustain more severe ulnar drift deformities than those with EXT2 mutations.

Radiographic characteristics of the hip joint in skeletally mature patients with multiple hereditary exostoses.

OBJECTIVE: To elucidate the radiological characteristics of the hips, especially in proximal femur, of skeletally mature patients with multiple hereditary exostoses (MHE). MATERIALS AND METHODS: Fifty eligible patients (100 hips) were included in the study and assigned to the MHE group. The control group included age- and sex-matched individuals, and the radiographs of 100 hips were used as controls. We examined the anatomical characteristics of the acetabulum and the proximal femur, including the acetabular depth-width ratio (ADR), Sharp's angle, femoral neck-shaft angle (NSA), Wiberg's centre-edge angle (CEA), femoral neck axis length (FNAL), femoral head diameter, (FHD), femoral neck width (FNW), femoral shaft width (FSW), femoral neck-shaft angle (NSA), and femoral head-neck ratio (FHNR = FHD/FNW). p value < 0.05 was considered significant. RESULTS: Osteochondroma was frequently observed in the medial femoral neck (79%), but it was rarely found in the femoral head (1%). ADR and Sharp's angle were not significantly different between the MHE and control groups (p = 0.2056, p = 0.5025). CEA was significantly different between the two groups (p < 0.0001). FNW was significantly larger in the MHE group than in the control group (p < 0.0001). FHNR was significantly different between the two groups (p < 0.0001). NSA was significantly larger than the MHE group (141.8° ± 9.7° vs 129.5° ± 5.6°, p < 0.0001). CONCLUSIONS: Hip dysplasia in the pelvic side was not commonly observed in skeletally mature MHE patients. However, they showed femoral neck widening and coxa valga. The occurrence of osteochondroma around the femoral neck affects the degree of valgus deformity. These facts could be useful for orthopaedic surgeons treating MHE patients.

Arthroscopic repair of horizontal cleavage meniscus tears provides good clinical outcomes in spite of poor meniscus healing.

PURPOSE: The purpose of this study was to evaluate the clinical outcomes and meniscus healing after arthroscopic repair of horizontal-cleavage meniscus tears, compared with vertical-longitudinal meniscus tears. METHODS: This was a retrospective review of a consecutive series of 52 meniscal repairs for horizontal-cleavage tears (n = 27) or vertical-longitudinal tears (n = 25); the groups were compared with respect to clinical symptoms and meniscal healing. Arthroscopic meniscal repair was performed using the inside-out technique with a marrow-stimulating technique. Clinical symptoms were evaluated using the Lysholm score and Knee injury and osteoarthritis outcome score (KOOS). Meniscus healing was evaluated by MRI. RESULTS: The mean follow-up periods were 35.4 ± 8.9 months in the horizontal-cleavage tear group and 39.8 ± 8.3 months in the vertical-longitudinal tear group. There were no significant differences in Lysholm score and KOOS, including each subscale, between the horizontal-cleavage tear- and vertical-longitudinal tear-groups at the final follow-up. At the final follow-up, MRI meniscus grades 0 and 1 were significantly more frequent in the vertical-longitudinal tear-group than in the horizontal-cleavage tear-group, while grade 3 was significantly more frequent in the horizontal-cleavage tear group than in the vertical-longitudinal tear group (p < 0.0001). CONCLUSIONS: Although meniscus healing of horizontal-cleavage tears may be poor, arthroscopic repair should be considered for horizontal-cleavage tears because it does provide good clinical outcomes. LEVEL OF EVIDENCE: IV.

Distal tibial tubercle osteotomy is superior to the proximal one for progression of patellofemoral osteoarthritis in medial opening wedge high tibial osteotomy.

PURPOSE: To investigate the effect of proximal tibial tubercle osteotomy (PTO) and distal tibial tubercle osteotomy (DTO) in medial opening wedge high tibial osteotomy on patellofemoral alignment, patellofemoral osteoarthritis and clinical outcomes. METHODS: PTO (n = 41) and DTO (n = 43) for the same surgical indications were included. Radiographic measurements of the Caton-Deschamps index, patellar tilt and shift, and arthroscopic cartilage evaluation at the patellofemoral joint were performed at osteotomy and plate removal. The Knee Society Score (KSS) was evaluated preoperatively and at the latest follow-up. RESULTS: The follow-up period was longer in the PTO group (33.7 months; range 23-40 years) than in the DTO group (22.2 months; range 18-29 months) (p < 0.0001), whereas the period from osteotomy to plate removal was not different between the groups. The Caton-Deschamps index of the DTO group was unchanged from 0.9 (range 0.7-1.2) to 0.9 (range 0.6-1.4), whereas that of the PTO group changed from 0.9 (0.7-1.2) to 0.7 (0.5-1.0) (p < 0.0001). There were fewer deteriorated cases of cartilage status in the trochlear groove in the DTO group (20.9%) than in the PTO group (56.1%, p < 0.05). There were more improved cases in the DTO group (23.3%) than in the PTO group (4.9%, p < 0.05). Postoperative KSS was better in the DTO group than in the PTO group (p < 0.05). CONCLUSION: DTO is associated not only with reduced deterioration but also with increased improvement of cartilage status in the trochlear groove and better KSS as compared with PTO. LEVEL OF EVIDENCE: IV.

ACL degeneration after an excessive increase in the medial proximal tibial angle with medial open wedge high tibial osteotomy.

PURPOSE: This study examined the influence of the mechanical medial proximal tibial angle (MPTA) on anterior cruciate ligament (ACL) degeneration following open wedge high tibial osteotomy (OWHTO). It was hypothesised that an excessive increase in MPTA would be associated with ACL degeneration following OWHTO. METHODS: Seventy-four knees treated with OWHTO were retrospectively examined. Arthroscopic ACL grading [0 (intact) to 4 (complete rupture)], anterior tibial translation (ATT) test at the time of OWHTO with the index arthroscopy and at plate removal with the second-look arthroscopy, clinical assessments using the Knee Society Score (KSS), and radiographic evaluations of MPTA were performed. The relationship between MPTA and the ACL condition was analysed using Spearman's correlation. RESULTS: The time from the index arthroscopy to the second-look arthroscopy was 15.0 ± 4.4 months; the total follow-up was 31.0 ± 6.5 months. ACL grade significantly increased from 0.6 ± 0.8 (index arthroscopy) to 1.1 ± 1.2 (second-look arthroscopy) (p < 0.0018). ATT on the operated side significantly decreased from 7.1 ± 2.6 mm preoperatively to 5.3 ± 2.3 mm at the time of plate removal (p < 0.001). No significant difference was observed in KSS for ACL grades in the steady and progression groups. Changes in MPTA from the preoperative to postoperative period were significantly higher in the progression group (p = 0.0155). Changes in ACL grades were significantly correlated with preoperative MPTA and changes in MPTA (r = - 0.365 and 0.343, respectively; p < 0.01). CONCLUSIONS: Excessively increased MPTA led to ACL degeneration following OWHTO. ACL degeneration was not associated with short-term clinical outcomes. Excessive correction of MPTA should be avoided to prevent ACL degeneration following OWHTO. LEVEL OF EVIDENCE: Therapeutic case series, Level IV.

Joint Space Width, but not Osteophyte Thickness, is a Reliable Indicator of Degeneration of Lateral Knee Joint Cartilage.

In this histologically controlled in vitro study, we evaluated the validity of plain radiography for the assessment of lateral knee joint cartilage degeneration (25 specimens). We examined the correlation between histological grade and radiography findings along with patient demographics. Our study indicated that the Mankin score had a significant inverse correlation with middle joint space width (JSW ; r=-0.19,P=0.02), but not with inner and outer JSW (inner : r=-0.11,P=0.10, outer : r=-0.14,P=0.06) under a non-weight bearing condition. The Mankin score had a significant inverse correlation with middle and outer JSW (middle : r=-0.17,P=0.04, outer : r=-0.14,P=0.04), but not with inner JSW (inner : r=-0.15,P=0.06) under valgus stress. There was no significant correlation between the Mankin score and osteophyte thickness (r=0.004,P=0.76). We also examined the correlation with patient demographics. We found that only the preoperative femorotibial angle had a significant inverse correlation with the Mankin score. These results indicate that JSW, but not osteophyte thickness, is reliable for evaluating lateral femoral cartilage degeneration.

Coronal tibiofemoral subluxation is correlated to correction angle in medial opening wedge high tibial osteotomy.

PURPOSE: This study aimed to analyse the change in coronal tibiofemoral (CTF) subluxation after high tibial osteotomy and to determine demographic variables associated with CTF subluxation. The change in CTF subluxation was hypothesised to be associated with the magnitude of correction of lower limb alignment and medial proximal tibial angle (MPTA). METHODS: A total of 103 consecutive knees in 86 patients who underwent medial opening wedge high tibial osteotomy for symptomatic medial compartment knee osteoarthritis were retrospectively analysed. The normal %CTF subluxation value, which was defined as a subluxation of the proximal tibia relative to the distal femur on the lateral edge of the femorotibial joint, was determined from 60 normal knees. The association between CTF subluxation and the Knee Society Score (KSS) and radiographic parameters was examined. RESULTS: The normal range for %CTF subluxation was defined as - 1.8 to 5.6%. Following osteotomy, Δ%CTF subluxation reduced from a mean of 4.5% (- 12.1 to - 4.6%) to 0.7% (- 6.8 to 8.2%), resulting in a decrease in lateral tibiofemoral subluxations concomitant with an increase in medial subluxations. The reduction in CTF subluxation correlated moderately with MPTA change (r = - 0.454, p < 0.001) and weakly with preoperative lower limb alignment as represented by hip-knee-ankle angle and %weight-bearing line. Multivariate regression analysis showed that ΔMPTA was a significant contributor of Δ%CTF subluxation. CONCLUSION: Osteotomy reduced CTF subluxation, which was correlated with MPTA change. Postoperative MPTA should be considered during surgical planning, and a postoperative MPTA of approximately 93.5° may be an appropriate target to reduce CTF subluxation by obtaining normal CTF congruency. LEVEL OF EVIDENCE: Level IV therapeutic, retrospective, cohort study.

Periarticular Injection of Tranexamic Acid Reduces Blood Loss and the Necessity for Allogeneic Transfusion After Total Knee Arthroplasty Using Autologous Transfusion: A Retrospective Observational Study.

BACKGROUND: This study aimed to examine the influence of a periarticular injection of tranexamic acid (TXA) on blood loss after a total knee arthroplasty (TKA) in patients who received an autologous blood transfusion. METHODS: We retrospectively reviewed the medical charts of 82 patients (88 consecutive knees) who underwent a primary unilateral TKA with or without a periarticular TXA injection (TXA and control groups, respectively). All patients underwent an autologous blood transfusion. Perioperative parameters related to blood loss were compared between groups. RESULTS: Compared to the control group, the decrease in hemoglobin was significantly smaller in the TXA group (1.5 ± 1.2 vs 2.5 ± 1.4 g/dL, P < .001), and blood drainage was significantly lower in the TXA group (387.2 ± 215.7 vs 582.3 ± 272.9 mL, P = .002). Moreover, the estimated blood loss, based on either hemoglobin or hematocrit, was significantly lower in the TXA group (509.8 ± 405.2 and 530.7 ± 418.5 mL, respectively) than in the control group (814.2 ± 543.8 and 809.1 ± 469.6 mL, respectively, both P < .001). No severe complications, including a venous thromboembolic event or infection, or local complications, including skin necrosis or delayed wound healing, were observed in either group. A postoperative allogeneic blood transfusion was performed in 2 cases in the control group and none in the TXA group. CONCLUSION: Periarticular TXA injection is effective in reducing postoperative blood loss and hemoglobin and hematocrit drops without increasing the risk of venous thrombosis or the necessity of an allogeneic blood transfusion.

New angle measurement device to control the posterior tibial slope angle in medial opening wedge high tibial osteotomy.

INTRODUCTION: Medial opening wedge high tibial osteotomy has been associated with an unintentional increase in the posterior tibial slope angle. We aimed to evaluate the effectiveness of a novel bone spreader angle rod to maintain the native posterior tibial slope angle in medial opening wedge high tibial osteotomy. MATERIALS AND METHODS: Data from 92 consecutive knees in 83 patients who underwent medial opening wedge high tibial osteotomy for knee osteoarthritis between March 2015 and June 2016 were analysed. The osteotomy was performed without the use of a bone spreader angle rod in the first 50 cases (control group) and with the use of the angle rod in the subsequent 42 cases (angle rod group). The wedge insertion angle, defined as the angle between a line drawn along the posterior aspect of the wedge spacer and a line tangential to the posterior aspect of the femoral condyles, and the posterior tibial slope angle were evaluated on pre- and postoperative lateral knee radiographs and postoperative computed tomography images. RESULTS: Wedge insertion angle showed that wedge spacers were inserted in a more direct horizontal direction in the angle rod group than in the control group (16.0 ± 8.8° and 23.0 ± 10.0°, respectively, P < 0.001). The pre- to postoperative change in posterior tibial slope angle was significantly smaller in the angle rod group (0.6 ± 1.6°) compared to that in the control group (3.2 ± 3.2°; P < 0.0001). A change of posterior tibial slope angle > 3° (outlier) was identified in 1 case (2.4%) in the angle rod group compared to 27 cases in the control group (54.0%). CONCLUSIONS: The direct horizontal insertion of wedge spacers with the assistance of our novel bone spreader angle rod maintains the native posterior tibial slope angle better than conventional methods. LEVEL OF EVIDENCE: IV.

Postoperative Anteroposterior Laxity Influences Subjective Outcome After Total Knee Arthroplasty.

BACKGROUND: We hypothesized that postoperative anteroposterior (AP) stability of the knee correlates with patient-reported clinical outcome and knee function after total knee arthroplasty (TKA). METHODS: This study enrolled 110 knees in 81 patients after TKA. AP laxity was measured with a KS Measure Arthrometer at 30°, 60°, and 90° flexion, which was confirmed with a goniometer. We assessed knee pain and function by using the Knee Society Function Score (KSS) and Knee Injury and Osteoarthritis Outcome Score (KOOS). Correlations among AP translation values and KOOS subscale scores (pain symptom, activities of daily living, and knee-related quality of life), KSS, and range of motion (ROM) were analyzed. RESULTS: The mean follow-up period for the assessment of the KOOS was 4.4 ± 2.2 years (range, 1.1-11.5 years). Twenty-five knees had posterior-stabilized fixed-bearing TKA, and 85 knees had posterior-stabilized mobile-bearing TKA. The mean KSS functional score and mean ROM were 96.3 ± 5.7 (range, 75-100) and 121.6° ± 14.4° (range, 90°-145°), respectively. The mean AP laxity was 4.5 ± 2.2 mm, 3.6 ± 1.9 mm, and 3.0 ± 1.9 mm at 30°, 60°, and 90° knee flexion, respectively. A significant inverse association was observed between AP laxity at 60° knee flexion and KOOS pain (P = .02∗, R2 = 0.05), but no significant association was found between AP laxity and other KOOS subscale score, KSS, and ROM. CONCLUSION: We found that the AP laxity at 60° knee flexion in this study significantly correlated with patient-reported pain. The observed AP laxity can be considered as a register of normal AP translations after arthroplasty.

Association of lubricin concentration in synovial fluid and clinical status of osteoarthritic knee.

OBJECTIVES: Although lubricin plays a role in controlling inflammation and pain as well as being a mechanical lubricant, clinical relevance of lubricin concentration in synovial fluid (SF) is unknown. The purpose was to determine whether lubricin concentration in SF is associated with the clinical status of the knee. METHODS: SF was obtained from 61 knee joints from patients who underwent any knee surgery with several stages of knee osteoarthritis. Lubricin/PRG4 concentration in SF was measured by enzyme-linked immunosorbent assay (ELISA). Clinical evaluations of the knee by the Kellgren and Lawrence (K-L) system, Knee Society Score (KSS), and the range of knee motion, and assessment of joint laxity were performed. Association of lubricin concentration in SF and these clinical factors was statistically analyzed. RESULTS: There was no significant correlation between lubricin concentration in SF and age, sex, K-L grade, or KSS. However, lubricin concentration was significantly correlated with anteroposterior laxity (R = 0.50, p < 0.001), full flexion angle (R = 0.39, p < 0.01), and range of knee motion (R = 0.38, p < 0.01), but not full extension angle, varus laxity, or valgus laxity. CONCLUSIONS: Lubricin concentration was correlated with joint flexibility, but not with clinical symptoms, including pain at that time.

Large-scale mutational analysis in the EXT1 and EXT2 genes for Japanese patients with multiple osteochondromas.

BACKGROUND: Multiple osteochondroma (MO) is an autosomal dominant skeletal disorder characterized by the formation of multiple osteochondromas, and exostosin-1 (EXT1) and exostosin-2 (EXT2) are major causative genes in MO. In this study, we evaluated the genetic backgrounds and mutational patterns in Japanese families with MO. RESULTS: We evaluated 112 patients in 71 families with MO. Genomic DNA was isolated from peripheral blood leucocytes. The exons and exon/intron junctions of EXT1 and EXT2 were directly sequenced after PCR amplification. Fifty-two mutations in 47 families with MO in either EXT1 or EXT2, and 42.3% (22/52) of mutations were novel mutations. Twenty-nine families (40.8%) had mutations in EXT1, and 15 families (21.1%) had mutations in EXT2. Interestingly, three families (4.2%) had mutations in both EXT1 and EXT2. Twenty-four families (33.8%) did not exhibit mutations in either EXT1 or EXT2. With regard to the types of mutations identified, 59.6% of mutations were inactivating mutations, and 38.5% of mutations were missense mutations. CONCLUSIONS: We found that the prevalence of EXT1 mutations was greater than that of EXT2 mutations in Japanese MO families. Additionally, we identified 22 novel EXT1 and EXT2 mutations in this Japanese MO cohort. This study represents the variety of genotype in MO.