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The use of commercial products such as a cup and liner for total hip arthroplasty for patients with severe bone defects has a high probability of failure. In these patients the cup alone cannot cover the bone defect, and thus, an additional augment or cage is required. In this study, we designed three-dimensional (3D) printable bone augments as an alternative to surgeries using reinforcement cages. Thirty-five sharp-edged bone augments of various sizes were 3D printed. A biporous structure was designed to reduce the weight of the augment and to facilitate bone ingrowth. Two types of frames were used to prevent damage to the augment’s porous structure and maintain its stability during printing. Furthermore, two types of holes were provided for easy augment fixation at various angles. Fatigue tests were performed on a combination of worst-case sizes derived using finite element analysis. The test results confirmed the structural stability of the specimens at a load of 5340 N. Although the porosity of the specimens was measured to be 63.70%, it cannot be said that the porous nature was uniformly distributed because porosity tests were performed locally and randomly. In summary, 3D-printable biporous bone augments capable of bonding from various angles and bidirectionally through angulation and bottom-plane screw holes are proposed. The mechanical results with bone augments indicate good structural safety in patients. However, further research is necessary to study the clinical applications of the proposed bone augment. Graphic abstract

Owing to an increase in the number of hip arthroplasty surgeries, the number of implant replacement surgeries is increasing rapidly as well. This necessitates the study of hip joint conditions. Therefore, Paprosky defined a classification system to indicate the degree of damage to the hip joint. In this study, a customised hip implant suitable for Paprosky classification Type ⅡC and over was designed. The shape, suitability, and mechanical safety of the worst-case model for the implant were evaluated.To identify the implant size depending on states over Type ⅡC acetabulum bone loss, a size range was selected and a customised implant was designed according to the computed tomography data within the size range. The implant was designed for the flange, hook, and flattened model types. The worst-case selection test was conducted using finite element analysis. The von Mises stresses of the flange, hook, and flattened models were found as 76.223, 136.99, and 80.791 MPa, respectively. Therefore, the hook-type model was selected as the worst case for the mechanical performance test.A bending test was conducted on the hook-type model without fracture and failure at 5344.56 N. The proposed customised implant was found suitable for Type ⅢA acetabulum bone loss, whereas the shape suitability and mechanical safety were verified for the worst case.The shape of a customised implant suitable for Paprosky ⅢA type was designed. The shape suitability and mechanical safety were evaluated using finite element method analysis and bending tests. Clinical validation is required through subsequent clinical evaluation.

Purpose: We attempted to determine the degree of rotation of the femoral component to achieve an ideal rectangular flexion gap with minimal medial collateral ligament (MCL) release using a modified measured technique. Materials and Methods: Group I consisted of 60 osteoarthritis patients (72 cases) who underwent total knee arthroplasty (TKA) with minimal MCL release and Group II consisted of 48 patients without osteoarthritis (61 cases). We performed computed tomography (CT) scanning of the knee with 90 degree flexion in all of the patients and analyzed the angles between the distal femur landmarks and the tibial mechanical axis using a Picture Archiving Communication system. External rotation of the femoral component from the Whiteside line and posterior condylar line was measured in group I who underwent TKA with minimum MCL release. The variance in the mediolateral flexion gap according to the degree of rotation was also measured using an Auto-Computer Aided Design program. Results: The CT scans showed that the Whiteside line, posterior condylar line, and transepicondylar line was more internally rotated on average from the longitudinal axis of tibia by 4.12°, 5.54°, and 4.64°, respectively, in group I compared to group II. In group I, the femoral component was inserted with an average external rotation of 5.6° from the posterior condylar line and with an average external rotation of 2.0° from the Whiteside line with minimal MCL release. From the measurements of the femoral component size and the variance in the degree of rotation using an Auto-CAD program, it was found that the change in the mediolateral flexion gap was greater when the rotation angle was greater and it was greater when the size of femoral component was larger at the same rotation angle. Conclusions: The average rotation angle of the femoral component to achieve an ideal rectangular flexion gap with minimal MCL release in TKA was an external rotation of 5.6° from the posterior condylar line and an external rotation of 2.0° from the Whiteside line. We concluded that when a femoral component is small in size, greater than average external rotation needs to be applied and when a femoral component is large in size, less than average external rotation needs to be applied.

We modified the posterior approach by preserving the external rotator muscles to enhance joint stability after primary THA. We asked whether this modified posterior approach would have a lower dislocation rate than the conventional posterior approach, with and without a repair of external rotator muscles. We retrospectively divided 557 patients (670 hips) who had undergone primary THA into three groups based on how the external rotator muscles had been treated during surgery: (1) not repaired after sectioning, (2) repaired after sectioning, or (3) not sectioned and preserved. The minimum followup was 1 year. In the group with preserved external rotator muscles, we observed no dislocations; in comparison, the dislocation rates for the repaired rotator group and the no-repair group were 3.9% and 5.3%, respectively. This modified posterior approach, which preserves the short external rotator muscles, seemed effective in preventing early dislocation after primary THA.Level III, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Background : Controversy continues regarding the best treatment for compression and burst fractures. The axial distraction reduction utilizing the technique emplying the long straight rod or curved short rod without derotation to reduce fracture are practised together with short segment posterolateral fusion (PLF). Effects of the early postoperative mobilization without posterolateral fusion on reduction maintenance and fracture consolidation were not evaluated so far. The present prospective study is designed to assess the effectiveness of i) reduction and restoration of sagittal alignment, ii) no posterolateral fusion on the reduced, fractured vertebral body and injured disc, iii) fracture consolidation and iv) the fate of the unfused cephalad and caudal injured motion segments of the fractured vertebra. Materials and Methods : The study includes 15 Denis burst and two Denis type D compression fractures between T 12 and L 3 . The lordotic distraction technique was used for ligamentotaxis utilizing the contoured short rods and pedicle screw fixator. Three vertebrae including the fractured one were fixed. The patient′s after surgery were braced for ten weeks with activity restriction for 2-4 weeks. The patients were evaluated for change in body height, segittal curve, reduction of retropulsion, improvement in neural deficit. The unfused motion segments, residual postoperative pain and bone and metal failure were also evaluated. Results : The pre-operative and postreduction percentile vertebral heights at, zero (immediate post-operative), at three, six and 12 months followup were 62.4, 94.8, 94.6, 94.5 and 94.5%, respectively. The percentages of the intracanal fragment retropulsion at pre operative, and post operative at zero, 3, 6 and 12 months followup were 59.0, 36.2,, 36.0, 32.3, and 13.6% respectively. The pre-operative and postreduction percentile loss of the canal dimension and at zero, three, six and 12 months were 52.1, 45.0, 44.0, 41.0 and 29% respectively suggesting that the under-reduced fragment was being resorbed gradually by a remodeling process. The mean initial kyphosis of 33° became mean 2° immediately after reduction and mean 3° at the final follow-up. The fractured vertebral bodies consolidated in an average period of ten weeks (range 8-14 weeks). The restored disc heights were relatively well maintained throughout the observation period. All paraparetic patients recovered neurologically. There were no postoperative complications. Conclusion : Instrument-aided ligamentotaxis for compression and burst fractures utilizing the short contoured rod derotation technique and the instrumented stabilization of the fractured spine are found to be effective procedures which contribute to the fractured vertebral body consolidation without recollapse and maintain the motion segment function.

Background: The aim of this study was to evaluate causes of unstable total knee arthroplasty and results of revision surgery. Methods: We retrospectively reviewed 24 knees that underwent a revision arthroplasty for unstable total knee arthroplasty. The average follow-up period was 33.8 months. We classified the instability and analyzed the treatment results according to its cause. Stress radiographs, postoperative component position, and joint level were measured. Clinical outcomes were assessed using the Hospital for Special Surgery (HSS) score and range of motion. Results: Causes of instability included coronal instability with posteromedial polyethylene wear and lateral laxity in 13 knees, coronal instability with posteromedial polyethylene wear in 6 knees and coronal and sagittal instability in 3 knees including post breakage in 1 knee, global instability in 1 knee and flexion instability in 1 knee. Mean preoperative/postoperative varus and valgus angles were 5.8°/3.2° (p = 0.713) and 22.5°/5.6° (p = 0.032). Mean postoperative α, β, γ, δ angle were 5.34°, 89.65°, 2.74°, 6.77°. Mean changes of joint levels were from 14.1 mm to 13.6 mm from fibular head ( p = 0.82). The mean HSS score improved from 53.4 to 89.2 (p = 0.04). The average range of motion was changed from 123° to 122° (p = 0.82). Conclusions: Revision total knee arthroplasty with or without a more constrained prosthesis will be a definite solution for an unstable total knee arthroplasty. The solution according to cause is very important and seems to be helpful to avoid unnecessary over-constrained implant selection in revision surgery for total knee instability.

Stainless steel is one of the most widely used biomaterials for internal fixation devices, but is not used in cementless arthroplasty implants because a stable oxide layer essential for biocompatibility cannot be formed on the surface. We applied a Ti electron beam coating, to form oxide layer on the stainless steel surface. To form a thicker oxide layer, we used a microarc oxidation process on the surface of Ti coated stainless steel. Modification of the surface using Ti electron beam coating and microarc oxidation could improve the ability of stainless steel implants to osseointegrate.The ability of cells to adhere to grit-blasted, titanium-coated, microarc-oxidated stainless steel in vitro was compared with that of two different types of surface modifications, machined and titanium-coated, and microarc-oxidated.We performed energy-dispersive x-ray spectroscopy and scanning electron microscopy investigations to assess the chemical composition and structure of the stainless steel surfaces and cell morphology. The biologic responses of an osteoblastlike cell line (SaOS-2) were examined by measuring proliferation (cell proliferation assay), differentiation (alkaline phosphatase activity), and attraction ability (cell migration assay).Cell proliferation, alkaline phosphatase activity, migration, and adhesion were increased in the grit-blasted, titanium-coated, microarc-oxidated group compared to the two other groups. Osteoblastlike cells on the grit-blasted, titanium-coated, microarc-oxidated surface were strongly adhered, and proliferated well compared to those on the other surfaces.The surface modifications we used (grit blasting, titanium coating, microarc oxidation) enhanced the biocompatibility (proliferation and migration of osteoblastlike cells) of stainless steel.This process is not unique to stainless steel; it can be applied to many metals to improve their biocompatibility, thus allowing a broad range of materials to be used for cementless implants.

Microarc oxidation (MAO) is a surface treatment that provides nanoporous pits, and thick oxide layers, and incorporates calcium and phosphorus into the coating layer of titanium alloy. We presumed such modification on the surface of titanium alloy by MAO would improve the ability of cementless stems to osseointegrate. We therefore compared the in vitro ability of cells to adhere to MAOed titanium alloy to that of two different types of surface modifications: machined and grit-blasted. We performed energy-dispersive x-ray spectroscopy and scanned electron microscopy investigations to assess the structure and morphology of the surfaces. Biologic and morphologic responses to osteoblast cell lines (SaOS-2) were then examined by measuring cell proliferation, cell differentiation (alkaline phosphatase activity), and alpha v beta 3 integrin. The cell proliferation rate, alkaline phosphatase activity, and cell adhesion in the MAO group increased in comparison to those in the machined and grit-blasted groups. The osteoblast cell lines of the MAO group were also homogeneously spread on the surface, strongly adhered, and well differentiated when compared to the other groups. This method could be a reasonable option for treating the surfaces of titanium alloy for better osseointegration.

Thirty-two adult patients with dens fractures (30 type II and 2 type III) were treated from 1983 to 2002 at the authors' institutions. The age of the patients ranged from 23 to 58 years. The postoperative follow-up period ranged from 1 to 10 years. The objective of this retrospective study was to evaluate the effectiveness of the osteosynthesis after screw fixation and postoperative bracing. In the 32 cases, 19 patients underwent single screw and 13 underwent double screw fixation. Postoperatively, light head halter traction was applied with the patients in bed for 1 to 4 weeks followed by a halo-vest for 8 to 14 weeks. Fractures healed in 9 weeks on average. There were no cases of delayed union. The overall results were excellent in 26 cases (81.3%), good in 5 (15.6%), and fair in 1 (3.1%) patient (who had a type Il fracture). There were no difference in dens union patterns between those receiving one-screw and two-screw fixation, and there were no complications during or after the operative procedure. Postoperatively there were no restriction of motion in the neck and no residual neck pain. Direct osteosynthesis of the fractured dens with screws is an effective procedure for unstable type II and III fracture of the dens. Postoperative external immobilization with a cervical brace seems to be an important contributing factor to the equal fusion rates in both groups of patients.

Study design: Pott's paraplegic patients with severe spinal deformity were reviewed retrospectively after being treated with chemotherapy and/or decompressive surgery. Objectives: To determine the most appropriate treatment protocol and to predict the prognosis for Pott's paraplegics with severe spinal deformity. Setting: Catholic University of Korea Medical Center and Moon-Kim's Institute of Orthopedic Research, Seoul, Korea from 1971 to 1996. Method: In this study, there were 33 patients (eight children and 25 adults), ranging from 13 to 56 years of age. They developed spinal tuberculosis at the age of 9 years (range, 2–29 years), and remained neurologically symptom free from an average of 16 years (range, 4–27 years). Four adults who responded well to treatment initially suffered relapses of paraplegia. Only six patients had previously received a full course of triple chemotherapy. Seven (two children, five adults) had healed disease, and 26 (six children, 20 adults) had active disease. Eleven cases had frequent drainage from the sinuses. Kyphoscoliosis was found in 11 patients: four children and seven adults. The remaining patients had kyphosis only. Among the 26 patients with active tuberculosis, 10 had triple chemotherapy itself and the rest had additional decompression surgery (10 anterior and six posterior). All seven patients with healed tuberculosis were subjected only to surgery (two anterior and five posterior). Results: In seven patients with healed tuberculosis, surgery did not improve neurologically except in one child patient. In four patients, the severity of paralysis remained unchanged and two patients, deteriorated neurologically after surgery. In six children with active tuberculosis, there were remarkable neurological recoveries by either conservative treatment or surgical decompression. Seven adults with active tuberculosis recovered slowly, improving by one or two Frankel grades (three Frankel C, three D, one E). In 11 out of 13 surgically treated adults with active disease, paralysis that had persisted for less than 3 months gradually improved by one or two Frankel grades. One Frankel A and one Frankel B paraplegic patients who had paralysis that had lasted through 6 months did not recover after surgery. Conclusion: The neurological recovery of Pott's paraplegics with severe spinal deformity resulted in three different outcomes: (1) severe deformity is different from moderate and mild deformities; (2) patients with healed tuberculosis had poorer prognosis than patients with active tuberculosis; (3) children had better prognosis than adults. Furthermore, patients with paralysis persisting over 6 months did not recover neurologically after surgery.

Purpose: The purpose of this study is to evaluate the clinical and radiologic results after high flexion Lospa (Corentec Inc.) and Scorpio NRG (Stryker Inc.) total knee arthroplasty. Materials and Methods: We prospectively compared 205 knees in 128 patients who underwent arthroplasty using Lospa (group A) and 164 knees in 102 patients who underwent arthroplasty using Scorpio NRG (group B) from September 2010 to March 2012 at Department of Orthopaedic Surgery, Sun General Hospital (Daejeon, Korea). Mean follow-up period was 23 months in group A and 24 months in group B. The radiologic analysis included the change of mechanical axis deviation and femoro-tibial angle, implant position (α, β, γ, δ), and patellar tilt. The clinical results were evaluated according to hospital for special surgery (HSS), knee society score (KSS), and range of motion. Results: Mechanical axis deviations were change in varus from 34.8 mm to 2.6 mm (p=0.02) in group A, and change in varus from 34.3 mm to 3.1 mm (p=0.04) in group B; no statistically significant difference was observed between them (p=0.13). Femoro-tibial angles were varus 4.3 to valgus 6.6 (p=0.02) in group A, and varus 4.4 to valgus 6.5 (p=0.03) in group B; no significant difference was observed between them (p=0.25). No significant difference in implant position was observed between the two groups (p=0.25 in α, p=0.17 in β, p=0.12 in γ, p=0.17 in δ). Mean HSS improved from 48.5 to 93.6 (p=0.02) in group A, and from 41.4 to 94.4 (p=0.01) in group B. Conclusion: Lospa total knee arthroplasty showed excellent early radiologic, clinical results and no statistically significant difference in the results was observed between Lospa and Scorpio NRG.

목적: 고령의 환자들에서 불안정한 대퇴골 전자간 골절의 치료로써 무시멘트 고관절 인공관절 전치 환술은 대퇴골 전자간 골절 치료로써 금속판이나 금속정 등의 내고정술 이외의 또 하나의 수술법으로 생각되고 있으며 대전자부 골편의 유합이 중요한 관심사 중의 하나이다. 이에 저자들은 이중 강선, 이중 고리, 8자 고정술을 이용한 대전자부 골편의 고정에 있어서 고정 방법에 따른 임상 및 방사선학적 결과를 발표하고자 한다. 대상 및 방법: 2010년 4월부터 2012년 2월까지 고관절의 불안정한 전자간 골절로 무시멘트 인공관절 전치환술 및 직경 1.0 mm의 이중 강선, 이중 고리, 8자 고정술을 시행 받은 20명 20예를 대상으로 하였다. 평균 연령은 71.1세(57-86세)였고 남자가 9명, 여자가 11명이었으며, 평균 추적관찰 기간은 6개월이었다. 술 후 환자들의 상태를 Harris hip score를 이용하여 평가하였다. 결과: 본 연구에서 수술 시간은 평균 95분, 수술 시 실혈량은 평균 800 cc였다. 최종 추시에서 Harris hip score는 평균 92.7점이었으며, 15예에서 보행거리의 감소없이 일상생활이 가능하였다. 술 후 고관절 탈구가 발생한 것은 1예였고, 고정 강선의 파손은 1예였다. 욕창과 심부정맥 혈전증 및 폐색전증이 발생한 사례는 없었다. 또한, 방사선학적으로 모든 사례에서 대퇴 주대는 해리 없이 잘 유지되었고, 13예에서 골절주위의 골생성을 확인할 수 있었으며, 골용해 소견을 보인 예는 없었다. 결론: 불안정성 대전자 골절 치료시 무시멘트형 인공고관절 치환술을 시행할 때 대전자부 골편을 고정하는데 이중강선, 이중고리, 8자 고정술을 이용한 강선 결박술이 유용한 방법으로 사료된다. 그러나 정복 방법의 개발과 함께 장기간의 추시결과에 대한 연구가 더욱 필요 할 것으로 사료된다.

대표적으로 측방 또는 전측방 도달법과 후방 도달법으 로 분류되는 인공 고관절 전치환 술의 수술적 도달법은 도 달의 용이성, 수술시간의 단축, 수술 시 출혈의 감소, 술 후 합병 발생 등의 다양한 조건을 고려하여 술자의 선호도 를 선택한다. 본 논문에서는 국내 및 미국 등의 여러 술자 들에 의하여 널리 사용되고 있는 후방 도달법에 대한 요 약을 통해 장단점을 설명하고, 이를 개선하기 위해 최근 김 등에 의해 소개된 바 있는 고관절 주위 단외회전근 (short external rotator)의 절단을 최소화하여 술후 관절 탈구 등의 합병증을 현저히 감소시켰다고 보고한 수정 후 방 도달법을 소개하고자 한다. 후방 도달 법은 술기가 용 이하고 수술시 출혈이 적고 감염이나 고관절 주위 화골성 근염 발생이나 외전근 손상, 감염률, 전색 등의 합병이 다 른 도달법에 비하여 적은 큰 장점을 가지고 있어 많은 술 자들이 선호하고 있는 도달 방법이지만 비구 노출이 제한적이고 좌골신경 손상의 위험이 있으며 특히 탈구율 0.3~2%로 보고 되는 측방 도달법에 비하여 술 후 관절 탈 구의 위험이 2~7%로 다소 증가한다는 단점을 가지고 있 는 것이 사실이다. 따라서 여러 장점과 더불어 관절 탈구의 위험을 현저히 감소 시킬 수 있다면 후방 도달법은 훨씬 더 많은 술자들이 가장 선호하는 수술 도달법이 될 것이며 본 논문에 소개하는 수정 후방 도달법은 하나의 좋 은 대안이 될 것으로 사료된다.

The objective of this study is to report on a case of a huge epidermoid cyst in the conus medullaris and cauda equina in a 43 year-old lady with the characteristic MRI and histologic findings. She suffered from low back pain, hypoesthesia around the anus and urinary incontinence for over 20 years. Since 15 years previously, she gradually developed right foot drop and muscle atrophy. She underwent surgery and unfortunately, she developed complete paralysis below T12 after complete tumor excision. At postoperative 4 weeks, evidence of partial neurological recovery down to the L3 roots was observed, but as yet there has been no further neurological recovery. Although total surgical excision is thought to be the only radical treatment, we recommend partial tumor excision to avoid damaging the spinal cord and cauda equina during the surgical procedure, than the radical excision, because this cyst is a very slowly growing benign tumor.

After open wedge high tibial osteotomy (OWHTO), the proximal fragment resembles the anatomy of the proximal tibia that is aligned in the anterior-posterior direction and the distal fragment resembles the anatomy of the mid shaft that is aligned in the proximal-distal direction. In addition, the medial portion of the proximal fragment becomes aligned medially and the medial portion of the distal fragment, laterally, depending on the magnitude of the posterior opening gap. Therefore, there would be a mismatch between the post-correction bony surface and the previous pre-contoured plate geometry. The purpose of this study was to devise a new plate that best fit the post-contoured anatomy of the tibia by evaluating the surface geometry of the plate positioning site after OWHTO. Thirty-one uni-planar and 38 bi-planar osteotomies were evaluated. Surgical indications were age of under 70 years, relatively active patient who performs recreational sports activities. Other indications were similar with general recommendation of HTO. Computed tomography (CT) of the operated knees was performed and it was used for the reconstruction of the 3D model. Bone model axis re-alignment was performed with coronal, sagittal, and axial plane. Morphologic analysis of the proximal tibia was performed using the following parameters: (1) radii in axial plane, 2) radii in coronal plane, and 3) angle and horizontal distance (Distance X) between the proximal and distal fragments. These were also analyzed according to the correction degree. The Analysis of Variance (ANOVA) test was conducted to verify the change depending on the correction amount of the posterior opening gap. The values obtained for the uni- and bi-planar osteotomy were compared by the independent t-test. There were 9 male and 60 female patients were recruited to this study; the mean age was 58.3 ± 8 and 56.9 ± 7.6 years, respectively. Preoperative weight bearing line (WBL) was 21.59 ± 11.36 and 22.32 ± 10.55 %, respectively. Mean correction degree was 10.9 ± 2.7 and 11.1 ± 2.6 mm, respectively. The radii of the tibial cross-sectional contour at the head portion tended to increase from the proximal to distal direction. The radii of the tibial cross-sectional contour at the neck portion tended to decrease from the proximal to distal direction. The radii of the coronal plane tended to increase from the proximal to distal direction. The angle between the proximal fragment and the distal one varied with the correction amount of the posterior opening gap. Shaft_Mid and Distance X of GroupI (110.08 mm and 6.11 mm, respectively) which had lower correction angle were lower than those of GroupII (130.05 mm and 6.41 mm, respectively) and those of GroupIII (136.35 mm, 8.01 mm, respectively) in coronal plane. There were significant differences (p = 0.023