Sang Heon Song

Oxford phase 3 unicompartmental knee replacement in Korean patients

Medium-term survivorship of the Oxford phase 3 unicompartmental knee replacement (UKR) has not yet been established in an Asian population. We prospectively evaluated the outcome of 400 phase 3 Oxford UKRs in 320 Korean patients with a mean age at the time of operation of 69 years (48 to 82). The mean follow-up was 5.2 years (1 to 10). Clinical and radiological assessment was carried out pre- and post-operatively. At five years, the mean Knee Society knee and functional scores had increased significantly from 56.2 (30 to 91) pre-operatively to 87.2 (59 to 98) (p = 0.034) and from 59.2 (30 to 93) to 88.3 (50 to 100) (p = 0.021), respectively. The Oxford knee score increased from a mean of 25.8 (12 to 39) pre-operatively to 39.8 (25 to 58) at five years (p = 0.038). The ten-year survival rate was 94% (95% confidence interval 90.1 to 98.0). A total of 14 UKRs (3.5%) required revision. The most common reason for revision was dislocation of the bearing in 12 (3%). Conversion to a total knee replacement was required in two patients who developed osteoarthritis of the lateral compartment. This is the largest published series of UKR in Korean patients. It shows that the mid-term results after a minimally invasive Oxford phase 3 UKR can yield satisfactory clinical and functional results in this group of patients.

Intraoperative blood loss during different stages of scoliosis surgery: A prospective study

BackgroundThere are a number of reasons for intraoperative blood loss during scoliosis surgery based on the type of approach, type of disease, osteopenia, and patient blood profile. However, no studies have investigated bleeding patterns according to the stage of the operation. The objective of this prospective study was to identify intraoperative bleeding patterns in different stages of scoliosis surgery.MethodsWe prospectively analyzed the estimated blood loss (EBL) and operation time over four stages of scoliosis surgery in 44 patients. The patients were divided into three groups: adolescent idiopathic (group 1), spastic neuromuscular (group 2) and paralytic neuromuscular (group 3). The per-level EBL and operation times of the groups were compared on a stage-by-stage basis. The bone marrow density (BMD) of each patient was also obtained, and the relationship between per-level EBL and BMD was compared using regression analysis.ResultsPer-level operation time was similar across all groups during surgical stage (p > 0.05). Per-level EBL was also similar during the dissection and bone-grafting states (p > 0.05). However, during the screw insertion stage, the per-level EBL was significantly higher in groups 2 and 3 compared to group 1 (p < 0.05). In the correction stage, per-level EBL was highest in group 3 (followed in order by groups 2 and 1) (p < 0.05). Preoperative BMD indicated that group 3 had the lowest bone quality, followed by groups 2 and 1 (in order), but the preoperative blood indices were similar in all groups. The differences in bleeding patterns in the screw insertion and correction stages were attributed to the poor bone quality of groups 2 and 3. Group 3 had the lowest bone quality, which caused loosening of the bone-screw interface during the correction stage and led to more bleeding. Patients with a T-score less than -2.5 showed a risk for high per-level EBL that was nine times higher than those with scores greater than -2.5 (p = 0.003).ConclusionsWe investigated the blood loss patterns during different stages of scoliosis surgery. Patients with poor BMD showed a risk of blood loss nine times higher than those with good BMD.

Complications and outcome of tibial lengthening using the Ilizarov method with or without a supplementary intramedullary nail: A CASE-MATCHED COMPARATIVE STUDY

We compared the complications and outcome of tibial lengthening using the Ilizarov method with and without the use of a supplementary intramedullary nail. In a retrospective case-matched series assembled from 176 patients with tibial lengthening, we matched 52 patients (26 pairs, group A with nail and group B without) according to the following criteria in order of importance: 1) difference in amount of lengthening (± 2 cm); 2) percentage difference in lengthening (± 5%); 3) difference in patients age (± seven years); 4) aetiology of the shortening, and 5) level of difficulty in obtaining the correction. The outcome was evaluated using the external fixator index, the healing index and an outcome score according to the criteria of Paley. It was found that some complications were specific to group A or B respectively, but others were common to both groups. The outcome was generally better in lengthenings with a nail, although there was a higher incidence of rectifiable equinus deformity in these patients.

Formation of induced anisotropy in amorphous Sm–Fe based thin films by field sputtering

Induced anisotropy with a large energy of 6×104 J/m3 is formed in an amorphous Sm–Fe based thin film by sputtering under an applied magnetic field of 500–600 Oe. The induced anisotropy results in a large anisotropy in magnetostriction, a strain anisotropy ratio reaching as high as 35, although intrinsic magnetostriction is affected only slightly. The large strain anisotropy allows one to realize a large strain in a particular direction and, hence, it is of significant practical importance. Induced anisotropy is also found to be formed by postannealing under applied magnetic field, but the magnitude of anisotropy energy formed is very small.

Comparison between upper and lower limb lengthening in patients with achondroplasia: a retrospective study

Lengthening of the humerus is now an established technique. We compared the complications of humeral lengthening with those of femoral lengthening and investigated whether or not the callus formation in the humerus proceeds at a higher rate than that in the femur. A total of 24 humeral and 24 femoral lengthenings were performed on 12 patients with achondroplasia. We measured the pixel value ratio (PVR) of the lengthened area on radiographs and each radiograph was analysed for the shape, type and density of the callus. The quality of life (QOL) of the patients after humeral lengthening was compared with that prior to surgery. The complication rate per segment of humerus and femur was 0.87% and 1.37%, respectively. In the humerus the PVR was significantly higher than that of the femur. Lower limbs were associated with an increased incidence of concave, lateral and central callus shapes. Humeral lengthening had a lower complication rate than lower-limb lengthening, and QOL increased significantly after humeral lengthening. Callus formation in the humerus during the distraction period proceeded at a significantly higher rate than that in the femur. These findings indicate that humeral lengthening has an important role in the management of patients with achondroplasia.

Bone tunnel widening with autogenous bone plugs versus bioabsorbable interference screws for secondary fixation in ACL reconstruction.

BACKGROUND Use of an autogenous bone plug for the tibial tunnel in anterior cruciate ligament (ACL) reconstruction has been advocated to achieve tendon-to-bone healing. Our hypothesis was that use of an autogenous bone plug, instead of a bioabsorbable interference screw, for secondary fixation of tendon allograft to the proximal part of the tibia would reduce the complication rate and tibial tunnel widening. METHODS We prospectively reviewed the cases of eighty-one patients (average age, 32.0 years) who had undergone ACL reconstruction with Achilles tendon allograft between 2000 and 2006. A bioabsorbable interference screw was used for the tibial tunnel in forty-one patients (group I). These patients were compared with forty patients in whom autogenous bone from the tibia had been used (group II). The two groups were assessed with use of the International Knee Documentation Committee (IKDC), Lysholm, and Tegner activity scores and with KT2000 arthrometer testing. The cross-sectional area perpendicular to the long axis of the tibial tunnel was calculated digitally with use of magnetic resonance imaging (MRI). RESULTS No significant differences were seen between the two groups with respect to IKDC, Lysholm, or Tegner activity scores or the results of laxity testing with arthrometry. A total of fourteen complications (34%) occurred in group I. In contrast, six complications (15%) were seen in group II (p = 0.046). The mean cross-sectional area enlargement was 38% in group I and 15% in group II (p = 0.017). CONCLUSIONS The clinical results associated with bioabsorbable screws and bone plugs were not significantly different. Laxity evaluation demonstrated no significant differences between bioabsorbable screws and bone plugs. Compared with bioabsorbable interference screws, autogenous bone plugs reduced the complication rate and tibial tunnel widening without inducing instability. We believe that an autogenous bone plug for the tibial tunnel is a reasonable option in selected patients.

New proposed clinico‐radiologic and molecular criteria in hypochondroplasia: FGFR 3 gene mutations are not the only cause of hypochondroplasia

We applied a comprehensive set of clinical and radiological criteria for the diagnosis of hypochondroplasia (HCH) in 160 patients with short stature 58 of whom were diagnosed to have HCH. Taking into account the genotypic and phenotypic variations in HCH, we conducted a study with these 58 patients and tested them for mutations in the fibroblast growth factor receptor 3 (FGFR3) and the short stature homeobox (SHOX) gene. We characterized the phenotypes by clinical and radiologic findings. In the patients with HCH, 19 were included in Group I (FGFR3 mutations—mutations of definite significance), and 39 were in Group II (6 SHOX mutations and 33 negative for disease‐causing FGFR3 mutations). The clinical findings were similar in two groups regardless of the presence or absence of mutations. More than 95% of the patients had mesomelic proportions. In Group I, the radiological findings of mesomelia of upper and lower limbs and, L1/L4 ratio in anterior–posterior and lateral view were more typical than in Group II. This study proposes comprehensive clinico‐radiological criteria for the diagnosis of HCH, which would help in detecting the true incidence of this underdiagnosed condition. The presence of SHOX mutations suggest genotypic–phenotypic overlap between HCH and Leri–Weill dyschondrosteosis, though further investigation is needed to effectively elucidate the importance of these mutations. Also, the 56.9% of HCH patients with negative mutations for FGFR3 suggests that there are other undiscovered gene mutations associated with this phenotypic entity.

Role of hybrid monolateral fixators in managing humeral length and deformity correction.

Background and purpose Humeral lengthening and deformity correction are now being done increasingly for various etiologies. Monolateral external fixators have advantages over traditional Ilizarov circular fixators; they are easy to apply, they are less bulky, and they are therefore more convenient for the patient. We assessed the effectiveness of hybrid monolateral lateral fixators in humeral lengthening and deformity correction. Methods We retrospectively reviewed 23 patients (40 humeri) with various pathologies who underwent lengthening—with or without deformity correction using monolateral external fixator—between 2003 and 2008. Mean age at the time of the surgery was 14 (10–22) years. The mean follow-up time was 3.4 (1–7) years. Results The average duration of external fixator use was 8.3 (6–19) months. The mean lengthening achieved was 8.8 (4–11) cm and percentage lengthening was 49% (19–73). The healing index was 28 (13–60) days/cm. The major complications were refracture in 3 humeri and varus angulation of 2 humeri. The minor complications were superficial pin tract infection (6 segments), transient radial nerve palsy (1 segment), and elbow flexion contracture (5 segments). All complications resolved. Interpretation Hybrid monolateral fixators can be used for humeral lengthening and deformity correction. The advantage over circular fixators is that they are less bulky and patients can perform their day-to-day activities with the fixator in situ.

Congenital pseudarthrosis of the tibia treated with a combination of Ilizarov's technique and intramedullary rodding.

Background and purpose Ilizarov’s technique and intramedullary rodding have often been used individually in congenital pseudarthrosis of the tibia. In this series, we attempted to combine the advantages of both methods while minimizing the complications. Methods We reviewed 15 cases of congenital pseudoarthrosis of the tibia (CPT) who were treated with a combination of Ilizarov’s apparatus and antegrade intramedullary nailing between 2003 and 2008. The mean age at surgery was 7.5 (3–12) years and the mean limb length discrepancy was 2.5 (1.5–5) cm. At a mean follow-up time of 4.5 (1.6–7.2) years after the index surgery, the patients were evaluated clinically and radiographically for ankle function (AOFAS score) and for malalignment, signs of union, limb length discrepancy, and complications. Results 14 patients achieved union, in 6 patients primary union and in 8 patients after secondary procedures. The AOFAS score improved from a preoperative mean of 40 (20–57) to 64 (47–75). The main complication was refracture in 1 patient, and non-union in 1 patient. Interpretation The combination of the Ilizarov technique and conventional antegrade intramedullary nailing was successful in achieving union with few complications, though this should be shown in long-term studies lasting until skeletal maturity.

Bone formation in a rat tibial defect model using carboxymethyl cellulose/BioC/bone morphogenic protein-2 hybrid materials.

The objective of this study was to assess whether carboxymethyl cellulose- (CMC-) based hydrogel containing BioC (biphasic calcium phosphate (BCP); tricalcium phosphate (TCP) : hydroxyapatite (Hap) = 70 : 30) and bone morphogenic protein-2 (BMP-2) led to greater bone formation than CMC-based hydrogel containing BioC without BMP-2. In order to demonstrate bone formation at 4 and 8 weeks, plain radiographs, microcomputed tomography (micro-CT) evaluation, and histological studies were performed after implantation of all hybrid materials on an 8 mm defect of the right tibia in rats. The plain radiographs and micro-CT analyses revealed that CMC/BioC/BMP-2 (0.5 mg) led to much greater mineralization at 4 and 8 weeks than did CMC/BioC or CMC/Bio/BMP-2 (0.1 mg). Likewise, bone formation and bone remodeling studies revealed that CMC/BioC/BMP-2 (0.5 mg) led to a significantly greater amount of bone formation and bone remodeling at 4 and 8 weeks than did CMC/BioC or CMC/BioC/BMP-2 (0.1 mg). Histological studies revealed that mineralized bone tissue was present around the whole circumference of the defect site with CMC/BioC/BMP-2 (0.5 mg) but not with CMC/BioC or CMC/BioC/BMP-2 (0.1 mg) at 4 and 8 weeks. These results suggest that CMC/BioC/BMP-2 hybrid materials induced greater bone formation than CMC/BioC hybrid materials. Thus, CMC/BioC/BMP-2 hybrid materials may be used as an injectable substrate to regenerate bone defects.