Search

Background This study investigated the epidemiology and causes of bearing dislocations following mobile-bearing unicompartmental knee arthroplasty (MUKA) and determined whether the incidence of primary bearing dislocations decreases as surgeon experience increases. Methods We retrospectively reviewed the bearing dislocations following MUKAs performed by 14 surgeons with variable experience levels. Causes of bearing dislocations were determined based on the surgical records, radiographs, and operator’s suggestion. Using a chi-squared test, the incidence of bearing dislocation was compared between the first 50, the second 50, and the next 100 unicompartmental knee arthroplasties (UKAs) of each surgeon's cohort. Results There were 67 (3.6%) bearing dislocations from 1853 MUKAs. The mean time to bearing dislocations after index MUKAs was 33 months (range, 1-144 months); 55% of the bearing dislocations occurred within 2 years after the index MUKAs. Primary bearing dislocations (n = 58) were the most common, followed by secondary (n = 6) and traumatic dislocations (n = 3). There was no significant difference in the incidence of bearing dislocation between the first 50 and second 50 UKAs for each surgeon. Two surgeons showed a significant decrease in bearing dislocations in their second 100 UKAs, while the other surgeons did not show a difference between their first 100 and second 100 UKAs. Conclusion Most bearing dislocations after MUKAs were related to technical errors such as component malposition or gap imbalance. This study did not confirm that the incidence of bearing dislocations decreases as the number of cases increases. Level of Evidence IV, Case series.

A new instrument system has been introduced to improve the accuracy and reproducibility of implant positioning in Oxford® unicompartmental knee arthroplasty (UKA). This study aimed to determine if the new instrumentation could improve postoperative implant positioning and limb alignment, and reduce the occurrence of outliers in Oxford® UKA.A total of 77 cases of Oxford® UKA with the new instrumentation were included. Individual matching for the conventional instrument group was performed according to age, sex, and body mass index. Postoperative radiological variables, including the hip-knee-ankle angle and the varus/valgus and flexion/extension angles of the femoral and tibial implants, were measured and compared between the new instrumentation group and the conventional group. The outliers in implant positions and postoperative complications were also compared.No significant between-group differences were observed in terms of lower limb alignment and tibial implant alignment. However, statistically significant differences were identified in the varus/valgus and flexion/extension angles of the femoral implant (P=0.01 and P0.001, respectively). More outliers were observed in the flexion/extension angles of the femoral and tibial implants in the new instrumentation group. Eight meniscal bearing dislocations and three lateral compartmental degenerative changes were found in the conventional group, while there were two meniscal bearing dislocations in the new instrumentation group during the study period.The present study did not confirm any benefit of the new instrument system in terms of postoperative limb alignment, positioning of the implant, or reducing outliers beyond the use of the conventional instruments.

Crepidiastrum denticulatum (Korean common name: i-go-deul-ppae-gi) is a valuable medicinal plant used in the pharmaceutical industry and as a raw material of functional foods. In this study, we investigated the effect of light quality on C. denticulatum growth, with the goal of improving the species’ biomass and bioactive compound content when grown in plant factories with artificial lighting. Three-week-old seedlings were grown for 6 weeks in a plant factory under fluorescent lamps (control) and various sets of light-emitting diodes (LEDs): three monochromatic [red (R), green (G), and blue (B)], several dichromatic RB with different ratios of R and B [R:B = 6:4 (R6B4), 7:3 (R7B3), 8:2 (R8B2), and 9:1 (R9B1)], and several trichromatic RGB [R:G:B = 5:1:4 (R5G1B4), 6:1:3 (R6G1B3), 7:1:2 (R7G1B2), 8:1:1 (R8G1B1), and 9:1:0 (R9G1B0)]. Shoot biomass (fresh weight), leaf area, leaf shape index, and water content of the shoot were significantly higher in the RGB group than in the monochromatic and RB groups. Increasing the percentage of R light improved shoot growth in the presence of G light, as in the RGB group, and this was accompanied by a high photosynthetic rate, light absorbance rate, and electron transport rate. The contents of total phenolics and hydroxycinnamic acids per unit dry weight did not differ between plants subjected to the different light quality treatments, and the contents per shoot were thus positively associated with shoot biomass. Overall, R8G1B1 was the most effective treatment for increasing shoot biomass and the accumulation of bioactive compounds; the shoot fresh weight and total hydroxycinnamic content of R8G1B1 were significantly higher, by 50 % and 60 %, respectively, than those of the control. Thus, light quality affects the biosynthesis of bioactive compounds and the shoot biomass of C. denticulatum.

This paper presents a novel morphing method for parameterizing patient-specific femur models based on femoral biomechanical functions. The proposed function-based morphing (FBM) method aims to provide a robust way to independently morph each partial functional region of the target femur structure by simply assigning the given functional parameters such as the femoral head diameter, neck length and diameter, and neck inclination angle. FBM includes three steps: (1) feature recognition to segment a femoral model into functional regions, (2) simplification to estimate the original parameters of the model and to define the morphing criteria as geometrical constraints, and (3) morphing to obtain the required shape by applying FBM fields that convert the terms of parametric changes into morphing vector terms for each segmented region. The proposed method was validated on a total of 48 patient-specific femur models. These models were parameterized and morphed without unexpected parametric changes, and the averaged error between the required parameters and the re-estimated parameters after morphing was 3.47%. Our observations indicate that the variation models developed in this study can be used as fundamentals for various functional sensitivity analyses for predicting changes in biomechanical responses due to the morphological changes of a subject-specific femur structure.

The purpose of this study is to present and evaluate a new arthroscopic technique using three-point suture fixation for anterior cruciate ligament (ACL) tibial avulsion fracture with accompanying detachment of the anterior horn of the lateral meniscus.Eleven patients with a diagnosis of ACL tibial avulsion fracture underwent arthroscopic suture fixation from January 2007 to December 2009. Out of the 11 patients, six had cases of ACL tibial avulsion fractures (four were type III and two were type IV) with accompanying detachment of the anterior horn of the lateral meniscus and were treated using three-point suture fixation. The patients were followed up and evaluated according to Lysholm scores, International Knee Documentation Committee (IKDC) subjective scores, Tegner activity level scales, anterior drawer testing and KT-2000 arthrometer testing.All patients were followed up for more than 2 years (range 25-40 months). The fracture fragments were united at a mean of 10.3 weeks (range 8-13). All patients were negative for the Lachman test and the anterior drawer test and had3 mm side-to-side difference with the KT-2000 arthrometer. The postoperative mean Lysholm score improved to 98 (range 96-100, P0.05). The postoperative mean IKDC subjective score was 93.3 (range 91-98, P0.05). The median Tegner score improved from 2.5 (range 2-3) to 8.5 (range 8-9) postoperatively (P0.05). The type of avulsion fracture (III or IV) did not significantly impact clinical results (Lysholm score, IKDC score, Tegner activity level, P0.05).ACL avulsion fractures with accompanying detachment of the anterior horn of the lateral meniscus should be treated as another type of ACL avulsion fracture. Arthroscopic treatment using the three-point suture fixation technique is effective for this type of ACL avulsion fracture and can restore the function and stability of the knee joint.

We evaluated the postoperative mechanical axis deviation and clinical outcome according to bearing size, femoral component position, and tibial resection angle after unicompartmental knee arthroplasty (UKA). A total of 104 patients with 124 knees underwent Oxford phase 3 UKA. The overall changes in mechanical axis deviation and tibiofemoral angle were significantly different according to bearing size (P = .001 and < .001), but they were not significantly different according to the tibial resection angle and femoral component position. The postoperative mechanical axis fell into the zone C or zone 2 in 108 knees (87%) and into the zone 3 or zone 4 in 16 cases (13%). One hundred eight cases, which had the mechanical axis passing the zone C or zone 2, did not show any progression of arthritis. Limb alignment is a function of the thickness of the bearing rather than alignments of femoral and tibial implant.

Purpose Radiographic carpal chondromalacia (RCC) was defined as the presence of cortical sclerosis or subchondral changes, such as a lucent defect or cystic changes in a carpal on plain radiographs. The purpose of this study was to investigate the factors associated with the occurrence of RCC in idiopathic ulnar impaction syndrome and to determine the efficacy of ulnar shortening osteotomy on patient outcome and RCC. Methods Thirty-nine patients (42 wrists) with idiopathic ulnar impaction syndrome were treated with either ulnar shortening osteotomy or arthroscopic wafer resection. Patients were divided into 2 groups according to the presence (RCC group; 17 patients, 19 wrists) or absence (non-RCC group: 22 patients, 23 wrists) of RCC on preoperative radiographs. To determine the factors associated with RCC, a comparative analysis of these 2 groups was performed with respect to sex, age, duration of symptoms, positive ulnar variance, pain scores, and Chun and Palmer grading system. The RCC area was measured on serial radiographs taken during follow-up. Progressive changes of RCC area and clinical outcomes were evaluated. Results Patients in the RCC group were older, exhibited greater positive ulnar variance, and demonstrated a significantly higher mean pain score before surgery. The RCC was found to reverse over the year following ulnar shortening osteotomy and did not recur up to 2 years after surgery. In 3 wrists, RCC had completely disappeared at the last follow-up. All patients showed improved clinical outcomes. Conclusions The RCC changes correlated with older age, a positive ulnar variance, and preoperative pain severity. The RCC progressively reversed after ulnar shortening osteotomy, and this reversal of radiographic changes correlated with clinical improvements. Type of study/level of evidence Therapeutic IV.

Background aims. Distraction osteogenesis (DO) is an increasingly popular technique used to stimulate new bone formation to treat orthopedic disorders resulting from bone defects and defi cits. Because of various possible complications that can occur during the long consolidation period, the development of procedures to accelerate regenerated ossifi cation is clearly desirable. The purpose of this study was to evaluate the effect of single insertions of bone morphogenic protein-2 (BMP-2), delivered by tri-calcium phosphate (TCP)/hydroxyapatite (HA), administered at osteotomy sites, on the rate of new bone formation during DO in a rat model. Methods . Thirty-six male Sprague ‐ Dawley rats, aged 12 weeks and weighing a mean ( standard deviation) of 401 14 g, were used in this study. The animals were randomized into three groups of 12 rats each. Group I served as a control, group II was treated with only TCP/HA, and group III was treated with recombinant human (rh) BMP-2-coated TCP/HA. Materials were inserted into the medullary canal at the femoral osteotomy site at the end of the lengthening period. After a 7-day latent phase, distraction was commenced on day 0 at a rate of 0.50 mm every 6 h for 5 days (2 mm daily), resulting in a total of 10 mm of lengthening by day 5. At two different time-points [at 4 weeks (day 33) and 8 weeks (day 61) after cessation of distraction], the progress of bone formation was determined with microcomputed tomography (micro-CT), histology and real-time polymerase chain reaction (PCR). The mean and standard deviation of the values obtained from the experiment were computed and statistical analyses performed using ANOVA . Statistical signifi cance was established at P 0.05. Results . Radiographically, all group III rat femurs exhibited bridging callus formation 8 weeks after cessation of distraction, whereas group II rat femurs demonstrated non-bridging callus formation. None of the group I rat femurs showed callus in the central zone of the distraction gap. For micro-CT, bone formation and remodeling of the distraction regeneration with beta-TCP/HA coated with rhBMP-2 had greater values than the control sides at all time-points. Two-dimensional quantitative analysis of the distraction regeneration showed that the bone volume of group III had higher values than groups I and II at 4 weeks ( P 0.05). This difference was also evident at 8 weeks. With hematoxylin and eosin (H&E) staining, the control group (group I) did not show any bone tissue at the distraction site. In group II at 4 weeks, abundant fi brous tissue surrounding the particles was visible with some areas of woven bone. At 8 weeks, the woven bone covered the particles but not the whole circumference. In group III at 4 weeks, much of the woven bone surrounded the particle with some fi brocartilagenous materials. At 8 weeks, woven bone covering the whole circumference of the particles was visible. Conclusions. Application of rhBMP-2, at the end of the rather rapid distraction period, as a single bolus signifi cantly increased the osteogenic process, while beta-TCP/HA behaved effectively as a sustained delivery system for this osteoinductive protein.

The authors present a case of bilateral stress fracture of the femoral shaft 15 years after total knee arthroplasty. Considerable femoral bowing deformity and varus malposition of the femoral and tibial components after total knee arthroplasty may produce abnormal stresses and lead to stress fracture of the distal femur in the region of greatest curvature.

Our purpose was to evaluate the result of radial tears at the root of the posterior horn of the medial meniscus (PHMM) in terms of tibiofemoral contact mechanics and the effectiveness of pullout sutures for such tears.Eleven mature pig knees each underwent 15 different testing conditions with an intact, simulated (incised) radial tear at the root of the PHMM and placement of pullout sutures in the radial tears of the medial meniscus at 5 different angles of flexion (0 degrees, 15 degrees, 30 degrees, 60 degrees, and 90 degrees ) under a 1,500-N axial load. A K-Scan pressure sensor (Tekscan, Boston, MA) was used to measure medial tibiofemoral contact area and peak tibiofemoral contact pressure. Data were analyzed to assess the difference in medial contact area and tibiofemoral peak contact pressure among the 3 meniscal conditions at various degrees of knee flexion.The mean contact area was significantly lower, and the peak tibiofemoral contact pressure was significantly high in knees with simulated radial tears at all angles of knee flexion compared with knees with intact menisci (P.0001). The peak tibiofemoral contact pressure after the pullout suture technique was significantly high at 0 degrees and 15 degrees of flexion (P.0001) compared with intact knee specimens. Failure of sutures occurred in 45% of the specimens at 0 degrees of flexion.Radial tears at the root of the PHMM in a porcine model significantly increased medial tibiofemoral contact pressure and decreased contact area. Although repair of tears of the PHMM with the pullout suture technique aids in significantly reducing tibiofemoral peak contact pressure between 30 degrees and 90 degrees , it remains significantly high at 0 degrees and 15 degrees of flexion.Pullout sutures for radial tears at the root of the PHMM may lead to an increase in peak medial tibiofemoral contact pressure and may be prone to mechanical failure, especially during the stance (loading) phase of gait (mean, 15 degrees of flexion).

The purpose of this study was to evaluate the biomechanical properties of 4 different graft fixation constructs on the tibial side of the posterior cruciate ligament with reconstruction by use of an Achilles tendon graft.Biomechanical testing of 4 different fixation techniques was performed on 20 human cadaveric tibias and Achilles tendons. Cross-pin fixation with bone blocks (group A), interference screw fixation with bone blocks (group B), cross-pin fixation of soft tissue with backup fixation (group C), and interference screw fixation of soft tissue with backup fixation (group D) were tested. The tibia-graft fixation complex was cyclically loaded between 50 N and 250 N at 1 Hz for 1,000 cycles. After cycling, the amount of graft displacement was determined by measuring the change in grip-to-grip distance. The complex was then loaded to failure at 1 mm/s, and maximum failure load, stiffness, and mode of failure were determined.Group C had a higher maximum failure load and stiffness than groups A and B (P.05 and P.001, respectively) but poor results for displacement (P.05 and P.05, respectively). The failure modes were bone block fracture, graft laceration, or cross-pin fracture in the cross-pin groups and graft pullout in the interference screw groups.Our study suggests that maximum failure load and stiffness of hybrid fixation for Achilles tendon graft are comparable to those of both single calcaneal bone plug fixation methods that we studied. However, tendon graft displacement was significantly greater regardless of fixation method when compared with bone plug fixation.Hybrid fixation for soft-tissue graft on the tibial fixation site provides comparable biomechanical properties of bone-to-bone fixation.

Summary Introduction Intramedullary nailing has long been used successfully in the treatment of aseptic nonunions of the femur and tibia. However, recently the efficacy of reamed intramedullary nailing in the treatment of nonunions of the femur has been questioned by some publications reporting unfavourable results. The purpose of this study is to evaluate the treatment results of femoral and tibial diaphyseal nonunions with intramedullary nailing. Patients and methods We retrospectively reviewed thirty-two patients with femoral or tibial diaphyseal nonunions who were treated with reamed intramedullary nailing between May 2002 and April 2006. Fixation status at the time of treatment were nail in twenty-eight patients (12 femurs, 16 tibiae), plate in three cases (2 femurs, 1 tibia), no implant in one femur. We used a dynamically locked, reamed intramedullary nailing. Only in bone defects greater than 50% of the cortical diameter and more than 2 cm in length was open bone grafting performed. Results Solid union was achieved in 93% (fourteen of fifteen) of femoral nonunions and 94% (sixteen of seventeen) of tibial nonunoins. Conclusions Our protocol with a dynamically locked, reamed nailing with the use of an oval hole and no open bone grafting for a defect less than 50% of the diameter and immediate weight bearing was successful in the treatment of femoral and tibial diaphyseal nonunions.