More accurate correction can be obtained using a three-dimensional printed model in open-wedge high tibial osteotomy.

PURPOSE: The purpose of this study was to compare the accuracy of the preoperative planning method using a three-dimensional (3D) printed model with that of a method using picture archiving and communication system (PACS) images in high tibial osteotomy (HTO). METHODS: Patients who underwent HTO using a 3D printed model (20 patients) and a method based on PACS images (20 patients) from 2012 to 2016 were compared. After obtaining the correction angle, in the 3D printed method, the wedge-shaped 3D printed model was designed. The PACS method used preoperative radiographs. The accuracy of HTO for each method was compared using radiographs obtained at the first postoperative year. The preoperative and postoperative posterior tibial slope angles were also compared. RESULTS: The weight-bearing line was corrected 21.2 ± 11.8% from preoperatively to 61.6 ± 3.3% postoperatively in the 3D group and from 19.4 ± 12.3% to 61.3 ± 8.1% in the PACS group. The mean absolute difference with the target point was lower in the 3D group (2.3 ± 2.5) than in the PACS group (6.2 ± 5.1; p = 0.005). The number of patients in an acceptable range was higher in the 3D group than in the PACS group. The posterior tibial slope angle was not significantly different in the 3D group (8.6°-8.9°), but was significantly different in the PACS group (9.9°-10.5°, p = 0.042). CONCLUSIONS: In open-wedge HTO, a more accurate correction for successful results could be obtained using the 3D printed model. LEVEL OF EVIDENCE: IV.

Angular deformity correction by guided growth in growing children: Eight-plate versus 3.5-mm reconstruction plate.

BACKGROUND: Guided growth using the eight-plate (8-plate) is the most commonly used method to correct angular deformities in children; however, implant failure has been reported. Recently, the 3.5-mm reconstruction plate (R-plate) has been used as an alternative option for guided growth; however, hardware prominence has been problematic. This study aimed to compare the coronal angular deformity correction results of guided growth between relatively thin 8-plates with cannulated screws and thick R-plates with solid screws. METHODS: Thirty-nine physes (24 distal femoral, 15 proximal tibial) in 20 patients underwent hemiepiphysiodesis using 8-plates, and 61 physes (40 distal femoral, 21 proximal tibial) in 35 patients underwent hemiepiphysiodesis using R-plates. Coronal angular corrections were measured and compared preoperatively, and after the completion of corrections. Amounts and rates of correction and complications were compared between the groups. RESULTS: Mean body mass index was 18.7 kg/m2 in the 8-plate group, and 22.7 kg/m2 in the R-plate group. Angular correction was achieved in all deformities at a mean of 13.7 months and 19.7 months in the 8-plate and the R-plate group, respectively. The mean corrected mechanical lateral distal femoral angle was 9.0° in the 8-plate group, and 9.9° in the R-plate group (P = 0.55). The mean corrected medial proximal tibial angle was 7.1° in the 8-plate group, and 9.0° in the R-plate group (P = 0.07). The mean rates of angular correction were also not significantly different in the distal femur (1.03°/month vs. 0.77°/month, P = 0.2) and the proximal tibia (0.66°/month vs. 0.63°/month, P = 0.77). There was one superficial infection in each group, and one case of implant failure in the R-plate group. Two rebound deformities were observed and needed repeat hemiepiphysiodesis. Permanent physeal arrest was not observed in this series.

Minimally invasive plate augmentation in the treatment of long-bone non-unions.

INTRODUCTION: Exchange nailing is most acceptable for treating hypertrophic non-union of the long bones, requiring the removal of previously fixed implant. However, its main effect of mechanical stabilization is controversial in non-isthmal area. We hypothesized that minimally invasive plate augmentation over the non-union site may have a better option, without the need of bone grafting or removing pre-existing implants. MATERIALS AND METHODS: Seventeen patients with hypertrophic non-union of the long bones between 2010 and 2014 on radiography who previously underwent intramedullary (IM) nailing or plate osteosynthesis for long-bone fractures were included. A locking compression plate was inserted with at least three mono- or bicortical screws at each proximal and distal segment. Broken or loosened interlocking screws of IM nail were simultaneously re-fixed. Fracture site exposure, pre-fixed implant removal, and bone grafting were not performed. We investigated whether union occurred and analyzed functional outcomes and complications. RESULTS: Eleven femoral and six tibial non-unions were prospectively included. In the pre-existing implants, 13 nails and 4 plates were found. All cases achieved union at a mean 22.7 weeks. One case of superficial infection was managed with oral antibiotics. Deep infection or implant failure did not occur. CONCLUSIONS: Minimally invasive plate augmentation can achieve additional stability and promote healing of hypertrophic non-union of the long bones. When indicated, this technique is the least invasive alternative to exchange nailing and reduces surgical risks in the treatment of diaphyseal non-union.

Factors influencing diagnosis and treatment of osteoporosis after a fragility fracture among postmenopausal women in Asian countries: a retrospective study.

BACKGROUND: A vast amount of literature describes the incidence of fracture as a risk for recurrent osteoporotic fractures in western and Asian countries. Osteoporosis evaluation and treatment after a low-trauma fracture, however, has not been well characterized in postmenopausal women in Asia. The purpose of this study was to characterize patient and health system characteristics associated with the diagnosis and management of osteoporosis among postmenopausal women hospitalized with a fragility fracture in Asia. METHODS: Patient surveys and medical charts of postmenopausal women (N=1,122) discharged after a fragility hip fracture from treatment centers in mainland China, Hong Kong, Singapore, South Korea, Malaysia, Taiwan, and Thailand between July 1, 2006 and June 30, 2007 were reviewed for bone mineral density (BMD) measurement, osteoporosis diagnosis, and osteoporosis treatment. RESULTS: The mean (SD) age was 72.9 (11.5) years. A BMD measurement was reported by 28.2% of patients, 51.5% were informed that they had osteoporosis, and 33.0% received prescription medications for osteoporosis in the 6 months after discharge. Using multivariate logistic regression analyses, prior history of fracture decreased the odds of a BMD measurement (OR 0.63, 95% CI 0.45-0.88). Having a BMD measurement increased the odds of osteoporosis diagnosis (OR 10.1, 95% CI 6.36-16.0), as did having health insurance (OR 4.95, 95% CI 1.51-16.21 for private insurance with partial self-payment relative to 100% self-payment). A history of fracture was not independently associated with an osteoporosis diagnosis (OR 0.80, 95% CI 0.56-1.15). Younger age reduced the odds of receiving medication for osteoporosis (OR 0.59, 95% CI 0.36-0.96 relative to age ≥65), while having a BMD measurement increased the odds (OR 1.79, 95% CI 1.23-2.61). CONCLUSIONS: Osteoporosis diagnosis and treatment in Asian countries were driven by BMD measurement but not by fracture history. Future efforts should emphasize education of general practitioners and patients about the importance of fracture.

A histomorphometric study of cellular layers after hemiepiphyseal stapling on the physeal plate in rabbits.

BACKGROUND: Epiphyseal stapling has been widely used to correct angular deformity. The mechanism, however, has not been well determined. To determine the effect of temporary hemiepiphyseal stapling on the cellular layers of the physis, a histomorphometric study was performed using immature rabbits. METHODS: Distal lateral epiphyseal stapling of the right femur was performed on 6-week-old New Zealand white rabbits. Thirty rabbits were randomly assigned to five groups, and six rabbits in each group were analyzed weekly for up to 5 weeks. RESULTS: The distal femur was deformed into the valgus, and the anatomical lateral distal femoral angle decreased with the passage of time. In the sequential histomorphometry of the operated physeal plate, the area ratio of each layer, compared to the control side, decreased every week. The total area of the physeal plate had decreased up to 60 % at the 5th week compared to the area of the 1st week, and the area of the proliferative layer decreased by the greatest amount among the three layers. CONCLUSIONS: Our findings suggest that the proliferation of chondrocytes seemed to be more suppressed by the compression of the stapling, thereby slowing the growth rate, although hypertrophy of the chondrocytes was also suppressed.

Clinical evaluation of a fluoroscopic image-based laser guidance system in bone tumor surgery: A technical note.

This study presents a laser guidance system developed to enhance surgical accuracy and reduce radiation exposure in orthopedic surgeries. The system can project the actual position corresponding to the appointed position selected by the surgeon on a fluoroscopic image using a line laser and has laser projection ability to mark the corresponding point using a line laser. The surgeon does not have to perform anatomical marker placement for calibration. Three patients with bone tumors underwent surgeries using the laser guidance system, and the projection accuracy was evaluated by measuring the distance error between the appointed and laser-marking positions. The installation time, including calibration, was also assessed for clinical usability. The average projection accuracy in bone tumor surgery was 2.86 mm, and the average installation time was 7 min. These results demonstrate that the laser guidance system, with a projection error of <3 mm, could be useful in bone tumor surgeries.

Non-Hodgkin's lymphoma at the medial clavicular head mimicking Tietze Syndrome.

We present a case of Non-Hodgkin's lymphoma involving medial clavicular head, which was initially diagnosed as Tietze syndrome. Non-Hodgkin's lymphoma arising from medial clavicular head is extremely rare, and CT, MRI findings have not been reported.

Minimal invasive surgery for unicameral bone cyst using demineralized bone matrix: a case series.

BACKGROUND: Various treatments for unicameral bone cyst have been proposed. Recent concern focuses on the effectiveness of closed methods. This study evaluated the effectiveness of demineralized bone matrix as a graft material after intramedullary decompression for the treatment of unicameral bone cysts. METHODS: Between October 2008 and June 2010, twenty-five patients with a unicameral bone cyst were treated with intramedullary decompression followed by grafting of demineralized bone matrix. There were 21 males and 4 female patients with mean age of 11.1 years (range, 3-19 years). The proximal metaphysis of the humerus was affected in 12 patients, the proximal femur in five, the calcaneum in three, the distal femur in two, the tibia in two, and the radius in one. There were 17 active cysts and 8 latent cysts. Radiologic change was evaluated according to a modified Neer classification. Time to healing was defined as the period required achieving cortical thickening on the anteroposterior and lateral plain radiographs, as well as consolidation of the cyst. The patients were followed up for mean period of 23.9 months (range, 15-36 months). RESULTS: Nineteen of 25 cysts had completely consolidated after a single procedure. The mean time to healing was 6.6 months (range, 3-12 months). Four had incomplete healing radiographically but had no clinical symptom with enough cortical thickness to prevent fracture. None of these four cysts needed a second intervention until the last follow-up. Two of 25 patients required a second intervention because of cyst recurrence. All of the two had a radiographical healing of cyst after mean of 10 additional months of follow-up. CONCLUSIONS: A minimal invasive technique including the injection of DBM could serve as an excellent treatment method for unicameral bone cysts.

Prognostic value of computed tomography for monitoring pulmonary metastases in soft tissue sarcoma patients after surgical management: a retrospective cohort study.

BACKGROUND: The lung is the most common site of metastases in patients with a soft tissue sarcoma. However, surveillance protocol for pulmonary metastasis after surgical management has not been proved. The goal of this retrospective study was to evaluate the prognostic value of computed tomography of the chest in soft tissue sarcoma patients after surgery. METHODS: A retrospective study was performed on 176 patients who were followed up with chest computed tomographic (CT) scan or plain chest radiographs for pulmonary metastasis monitoring after surgery. Ninety-six patients were followed up with plain chest radiographs and 80 patients with chest CT scan. Mean duration of follow-up was 55.8 months. The Kaplan-Meier method and the log-rank test were used to calculate overall survival rates and survival rate difference between chest CT and plain radiograph cohorts. RESULTS: The overall 5- and 10-year survival rates of 176 patients were 75.6% and 70.3%, respectively. The 5-year survival estimates of 96 patients who were included in the plain radiograph cohort and 80 patients in the chest CT cohort were 74.2% and 76.6%, respectively (P=0.70). Fifty-four patients (30.7%) had pulmonary metastasis. Of the 54 patients, 26 belonged to the plain radiograph cohort and 28 patients belonged to the chest CT cohort. Pulmonary metastasis of chest CT cohort had the tendencies of unilaterality, a smaller number of patients, and management with metastasectomy other than palliative management. The 2- and 4-year survival ratess after detection of pulmonary metastasis were 20.1% and 0% in the plain radiograph cohort and 47.4% and 31.6% in the chest CT cohort (P<0.05). CONCLUSION: Serial monitoring with chest CT could give rise to early detection of pulmonary metastases, chance for metastasectomy, and eventually survival advantage.

Direct application of MR images to computer-assisted bone tumor surgery.

BACKGROUND: We describe a method for the direct application of MR images to navigation-assisted bone tumor surgery as an alternative to CT-MRI fusion. METHOD: Six patients with an orthopedic malignancy were employed for this method during navigation-assisted tumor resection. Tumor types included osteosarcoma (4), high-grade chondrosarcoma (1), and adamantinoma (1). Mean patient age was 25.3 years (range 18-52 years). Mean duration of follow-up was 25.8 months (range 18-32 months). Resorbable pin placement and rapid 3-dimensional spoiled gradient echo sequences made the direct application of MR images to computer-assisted bone tumor surgery without CT-MR image fusion possible. A paired-point registration technique was employed for patient-image registration in all patients. RESULTS: It took 20 min on average to set up the navigation (range 15-25 min). The mean registration error was 0.98 mm (range 0.4-1.7 mm). On histologic examination, distances from tumors to resection margins were in accord with preoperative plans. No patient had a local recurrence or distant metastasis at the last follow-up. CONCLUSION: Direct patient-to-MRI registration is a very useful method for bone tumor surgery, permitting the application of MR images to intraoperative visualization without any additional costs or exposure of the patient to radiation from the preoperative CT scan.

Pullout strength of pedicle screws using cadaveric vertebrae with or without artificial demineralization.

OBJECTIVES: To evaluate the differences in the pullout strength and displacement of pedicle screws in cadaveric thoracolumbar vertebrae with or without artificial demineralization. METHODS: Five human lumbar and five thoracic vertebrae from one cadaver were divided into two hemivertebrae. The left-side specimens were included in the simulated osteopenic model group and the right-side bones in a control group. In the model group, we immersed each specimen in HCl (1 N) solution for 40 minutes. We measured bone mineral density (BMD) using dual-energy X-ray absorptiometry and quantitative computerized tomography. We inserted polyaxial pedicle screws into the 20 pedicles of the cadaveric lumbar and thoracic spine after measuring the BMD of the 2 hemivertebrae of each specimen. We measured the pullout strength and displacement of the screws before failure in each specimen using an Instron system. RESULTS: The average pullout strength of the simulated osteopenic model group was 76% that of the control group. In the control and model groups, the pullout strength was 1678.87±358.96 N and 1283.83±341.97 N, respectively, and the displacement was 2.07±0.34 mm and 2.65±0.50 mm, respectively (p<.05). We detected positive correlations between pullout strength and BMD in the control group and observed a negative correlation between displacement and BMD in the model group. CONCLUSIONS: By providing an anatomically symmetric counterpart, the human cadaveric model with or without demineralization can be used as a test bed for pullout tests of the spine. In the simulated osteopenic model group, pullout strength was significantly decreased compared with the untreated control group. CLINICAL SIGNIFICANCE: Decreased bone mineral density may significantly reduce the pullout strength of a pedicle screw, even though the range is osteopenic rather than osoteoporotic.

Conventional bicortical pin substitution with a novel unicortical pin in external fixation: A biomechanical study.

INTRODUCTION: As most patients with polytrauma or open fractures are converted from temporary external fixation to definite stabilization, the prevention of complications such as infection is especially important. To overcome the high risk of infection associated with the use of the conventional bicortical pin for temporary external fixation, the authors developed a novel unicortical pin and analyzed it in a biomechanical study. METHODS: The unicortical pin consisted of an inner screw, purchasing the cortical bone, and an outer sleeve with 6 spikes. A bicortical pin was used for the purpose of comparison. A fracture gap model was stabilized using a monoplanar configuration. Both the unicortical pins (Uni group) and bicortical pins (Bi group) underwent axial compressive and torsional load testing using a servo-hydraulic testing machine. Stiffness, load to failure, and mode of failure were documented. RESULTS: Stiffness and load to failure of the Uni group (average, 40.5 N/mm and 1098.4 N, respectively) were greater than that of the Bi group (average, 33.7 N/mm and 968.6 N, respectively) in the axial compressive load test (P = 0.008 and 0.032). Stiffness and load to failure of the Uni group (average, 1.2 Nm/degree and 1.7 Nm, respectively) were also significantly higher than those of the Bi group (average, 0.8 Nm/degree and 0.6 Nm, respectively) in the torsional load test (P = 0.008 and 0.016). All pins in the Bi group were bent at the pin-synthetic bone interface without synthetic bone failure. Contrarily, the Uni group did not show any pin bending or failure. However, in the axial compression test, partial cracks in the synthetic bone were found at the interface with spikes in the outer shell. In addition, in the torsion test, incomplete fractures were seen through the inner screws' holes. CONCLUSION: Compared with the conventional bicortical pin, the newly designed unicortical pin significantly increased fracture stability under both axial compressive and torsional loads. The unicortical pin can be considered an alternative biomechanical solution to obtain adequate stability when performing external fixation of fractures.

Articular surface area of the coronoid process and radial head in elbow extension: surface ratio in cadavers and a computed tomography study in vivo.

PURPOSE: To quantify the articular surface area ratio of the radial head to the coronoid process to gain a better understanding of the stress distribution across these articulations and possibly to explain the patterns of osteoarthritis that are commonly seen in the elbow. METHODS: Thirty cadaveric elbows were harvested and dissected to allow measurement of the radial head and coronoid process articular surfaces. The articular surface areas were measured using the Image J program (National Institutes of Health, Chicago, IL). Twelve men were recruited for this study, and all received a computed tomography (CT) scan of the elbow. A 3-dimensional image of the proximal radioulnar articular surface was created using volume rendering. All specimens were measured 3 times by 2 observers. RESULTS: In the cadaveric measurements, the mean area of the radial head articular fossa was 247.3 +/- 52.6 mm(2) (mean +/- SD). The mean area of the medial facet of the coronoid process was 232.29 +/- 36.5 mm(2), and the mean area of the lateral facet was 141.9 +/- 33.3 mm(2). The articular surface area ratio of radial head to coronoid process was 1:1.5. In the CT measurement, the mean area of the radial head articular fossa was 258.9 +/- 26.3 mm(2). The mean area of the coronoid process articular surface was 376.9 +/- 37.0 mm(2). The articular surface area ratio of radial head to coronoid process was 1:1.46. CONCLUSIONS: The ratio of articular surface area of radial head to coronoid process is 1:1.51 in cadavers and 1:1.46 using a CT in vivo, which is the reverse of the reported force transmission ratio across the elbow joint.

An anatomic study on the junctura tendinum in the 4th intermetacarpal space and its clinical implication.

We report results of anatomic study in the fourth intermetacarpal space, focusing on the pattern of junctura tendinum and variations of extensor tendons of the little finger with its clinical implication on snapping of the little finger. Fifty unpaired cadaveric hands were dissected from the wrist to the middle phalanx of the ring and little fingers. The type of junctura tendinum was judged based on Von Schroder's classification and the relationship with EDC were recorded. EDC to the little finger and EDM were dissected and the numbers were recorded. Forty six hands (92%) exhibited a junctura tendinum in the fourth intermetacarpal space and it was Type III in 42 hands (84%). The EDC-little finger was absent in 76% (38 of 50 hands). When present, EDC-little finger originated most commonly as single thin tendon. The absence of an EDC-little finger was associated with increased incidence of Type III junctura tendinum (37 of 38 hands). An EDM was present in all 50 hands running from the fifth dorsal compartment. Based on these clinical and anatomic studies, we considered that the snapping of the little finger is more likely subluxation of junctura tendinum rather than subluxation/dislocation of EDC of the little finger.

Giant cell tumor of the femoral head and neck: result of intralesional curettage.

BACKGROUND: There have been not much reports on the result of intralesional excision for giant cell tumors (GCTs) of the femoral head and neck because of its rarity. The purpose of this study is to review the results of patients managed with intralesional curettage for GCT of the femoral head and neck. METHODS: We retrospectively reviewed 12 patients with a GCT of the femoral head and/or neck. All of them were treated with curettage and followed up to monitor local recurrence and pulmonary metastasis. Mean duration of follow-up was 58.3 months. RESULTS: Although recurrence rate of the present study was rather high (41.7%, 5 of 12 hips), 9 of 12 hips (75%) were preserved at last follow-up including 2 hips that underwent repeat curettage, and functional outcomes of the preserved hips were satisfactory. CONCLUSION: It may be that curettage should be considered as a primary treatment of choice for GCTs of the femoral head and neck.

Comparison of monthly ibandronate versus weekly risedronate in preference, convenience, and bone turnover markers in Korean postmenopausal osteoporotic women.

Patient preferences, convenience, and bone turnover markers were evaluated for the monthly ibandronate over the weekly risedronate regimen in Korean postmenopausal osteoporotic women. This was a 6-month, prospective, randomized, open-label, multicenter study with a two-period and two-sequence crossover treatment design. After a 30-day screening period, eligible participants with postmenopausal osteoporosis were randomized to receive either monthly oral ibandronate 150 mg for 3 months followed by weekly oral risedronate 35 mg for 12 weeks (sequence A) or the same regimen in reverse order (sequence B). Patient preference and convenience were evaluated by questionnaire. The changes in serum C-telopeptide after 3 months of treatment were analyzed. A total of 365 patients were enrolled in this study (sequence A 182, sequence B 183). Of patients expressing a preference (83.4%), 74.8% preferred the monthly ibandronate regimen over the weekly regimen (25.2%). More women stated that the monthly ibandronate regimen was more convenient (84.2%) than the weekly regimen (15.8%). There was no significant difference in the change in bone turnover marker between the two treatments. The two regimens were similarly tolerable. There were fewer adverse events in the monthly ibandronate group compared to the weekly risedronate group in terms of gastrointestinal side effects (nausea and abdominal distension). This study revealed a strong preference and convenience for monthly ibandronate over weekly risedronate in Korean postmenopausal osteoporotic women. There was no significant difference in change of bone turnover marker and safety profile between the two regimens.

Analysis of early failure of the locking compression plate in osteoporotic proximal humerus fractures.

BACKGROUND: Although there has been continuous evolution in the management of fracture fixation, treatment for osteoporotic proximal humerus fractures is still challenging to trauma surgeons. The purpose of this study was to report early failure of the locking compression plate (LCP) in the treatment of osteoporotic proximal humerus fracture and characterize the mode of failure. METHODS: Nine patients, older than 65 years, underwent internal fixation with the use of a locking compression plate and had early failure within 4 weeks postoperatively. According to Neer's classification, five were included in a two-part surgical neck fracture, three in a three-part fracture, and one in a four-part fracture. RESULTS: All failures occurred with back-out of the plate-screw construct, leading to varus displacement in eight patients and plate breakage in one. Revision surgery was performed in six patients using replating and tension band wiring with a bone graft, and three patients underwent hemiarthroplasty. The average UCLA score was 25 points for the hemiarthroplasty group and 30 points for the reconstruction group. CONCLUSIONS: Early postoperative failure of the LCP developed within 4 weeks with a presentation of en bloc back-out of the plate-screw construct and plate breakage. Possible risk factors included malreduction, loss of medial support, and negligence of tension band sutures on the tuberosities.

Surgical management of unstable elbow dislocation without intra-articular fracture.

The purpose of this study was to describe soft tissue injury patterns and report the clinical results of primary ligament repair with use of protected early mobilisation in unstable elbow dislocations with pure capsulo-ligamentous injuries. Twenty-four patients who presented with traumatic unstable elbow dislocation without associated intra-articular fracture were reviewed. Anatomical repair was performed using metal anchor screws and the bone tunnel method. Ligament avulsion was noted in 55% for the medial collateral ligament, 80% for the lateral collateral ligament, 60% for the flexor tendon and 80% for the extensor tendon. The overall mean Mayo Elbow Performance Score was 93.2. Brachial artery injuries occurred in two elbows. Heterotopic calcification was noted in 14 patients and there was one severe traumatic arthrosis. This study showed a high incidence of reattachable avulsion injuries to ligaments, tendon/muscle and capsule in unstable elbow dislocations. Primary ligament repair coupled with early rehabilitation provided satisfactory outcomes at two to four years postoperatively.

Evaluation of Accuracy of a Three-Dimensional Printed Model in Open-Wedge High Tibial Osteotomy.

The purpose of this study was to evaluate the usefulness of a three-dimensional (3D) printed model for open-wedge high tibial osteotomy (HTO). This study retrospectively evaluated 20 patients with medial knee osteoarthritis and varus deformity. Between October 2015 and July 2016, the patients underwent open-wedge HTO using a 3D printed model. The mean age of patients was 55.2 years (range, 51-60 years). The mean preoperative mechanical femorotibial angle (mFTA) was varus 7.8 degrees (range, varus 4.7-11.6 degrees). After measuring the target angle using full-length lower limb weight-bearing radiography, the osteotomy was simulated using 3D images obtained from computed tomography (CT) with the 3D Slicer program. On the basis of the simulated osteotomy section and the target angle, the model was then designed and printed. Open-wedge HTO was then performed by applying the 3D printed model to the opening gap. The accuracy of osteotomy and the change in posterior tibial slope (PTS) angle were evaluated. The weight-bearing line on the tibial plateau was corrected from a preoperative mean of 19.5 ± 9.8% to a postoperative mean of 63.1 ± 6.1% (p < 0.001). The postoperative values were not statistically significantly different from the preoperative target points (p = 0.688). The mFTA was corrected to a postoperative mean of valgus 3.8 ± 1.4 degrees. The PTS angle showed no significant change (p = 0.256). A 3D printed model using CT may be useful for preoperative planning of open-wedge HTO. Satisfactory correction can be obtained without a change in the PTS.

Additional fixation of medial plate over the unstable lateral locked plating of distal femur fractures: A biomechanical study.

INTRODUCTION: Lateral locked plating is a standard treatment option for distal femur fractures. However, the unstable conditions after lateral locked plating are increasing. The objective of this study was to investigate the biomechanical strength of additional medial plate fixation over the unstable lateral locked plating of distal femur fractures. MATERIALS AND METHODS: A distal femur fracture model (AO/OTA 33-A3) was created with osteotomies in the composite femur. Three study groups consisting of 6 specimens each were created for single-side lateral locked plating with 6 distal locking screws (LP-6), single-side lateral locked plating with 4 distal locking screws (LP-4), and additional medial locked plating on LP-4 construct (DP-4). A compressive axial load (10 mm/min) was applied in the failure test. Mode of failure, load to failure, and ultimate displacement were documented. RESULTS: All single-side lateral locked plating (LP-4 and LP-6) showed plate bending at the fracture gap, while none of the DP-4 showed plate bending at the fracture gap. Load to failure of DP-4 (mean 5522 N) was 17.1% greater than that of LP-6 (mean 4713.3 N, p < 0.05) and 29.2% greater than that of LP-4 (mean 4273.2 N, p < 0.05). Ultimate displacement of DP-4 (mean 5.6 mm) was significantly lower than that of LP-6 (mean 8.8 mm, p < 0.05) and LP-4 (mean 9.1 mm, p < 0.05). CONCLUSIONS: Additional fixation of medial plate significantly increased the fracture stability in distal femur fractures fixed with the lateral locked plating. Especially in the clinical situations where sufficient stability cannot be provided at the distal segment, the medial plate may be considered as a useful biomechanical solution to obtain adequate stability for fracture healing.