A Pilot Experiment to Measure the Initial Mechanical Stability of the Femoral Head Implant in a Cadaveric Model of Osteonecrosis of Femoral Head Involving up to 50% of the Remaining Femoral Head.

Background and Objectives: Currently, only patients with osteonecrosis of the femoral head (ONFH), who had bone defects involving 30-33.3% of the remaining femoral head, are indicated in hip resurfacing arthroplasty (HRA). In an experimental cadaver model of ONFH involving up to 50% of the remaining femoral head, the initial stability of the femoral head implant (FHI) at the interface between the implant and the remaining femoral head was measured. Materials and Methods: The ten specimens and the remaining ten served as the experimental group and the control group, respectively. We examined the degree of the displacement of the FHI, the bonding strength between the FHI and the retained bone and that at the interface between the FHI and bone cement. Results: Changes in the degree of displacement at the final phase from the initial phase were calculated as 0.089 ± 0.036 mm in the experimental group and 0.083 ± 0.056 mm in the control group. However, this difference reached no statistical significance (p = 0.7789). Overall, there was an increase in the degree of displacement due to the loading stress, with increased loading cycles in both groups. In cycles of up to 6000 times, there was a steep increase. After cycles of 8000 times, however, there was a gradual increase. Moreover, in cycles of up to 8000 times, there was an increase in the difference in the degree of displacement due to the loading stress between the two groups. After cycles of 8000 times, however, such difference remained almost unchanged. Conclusions: In conclusion, orthopedic surgeons could consider performing the HRA in patients with ONFH where the bone defects involved up to 50% of the remaining femoral head, without involving the femoral head-neck junction in the anterior and superior area of the femoral head. However, more evidence-based studies are warranted to justify our results.

Shape suitability and mechanical safety of customised hip implants: Three-dimensional printed acetabular cup for hip arthroplasty.

Background: 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. Materials and methods: 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. Results: 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. Conclusion: 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.

The Fixation Method according to the Fracture Type of the Greater Trochanter in Unstable Intertrochanteric Fractures Undergoing Arthroplasty.

PURPOSE: We conducted a study on patients who underwent hip joint arthroplasty because of unstable femur intertrochanteric fractures with greater trochanter bony fragments. After dividing patients into three groups depending on their fracture patterns, we evaluated the clinical and radiological outcomes of different operation methods applied to each of these groups. MATERIALS AND METHODS: Using Evan's classification, we defined an unstable intertrochanteric fracture as those characterized as stage 4 or 5. Of the 137 patients presenting with an intertrochanteric fracture with osteoporosis (bone mineral density, <-2.5) between March 2014 and October 2015, 63 met the eligibility criteria and were included in this study. Next, patients were divided into three groups based on their greater trochanter fracture patterns (discerned with three-dimensional computed tomography images); different fixation methods were applied to each group by a single orthopaedic surgeon. RESULTS: Taken as a whole, 50 out of 63 patients experienced no reduction in walking distance in their daily lives. Harris hip score increased from 74.8 to 85.7 point and we considered this a relatively good result. Radiologically, we observed complete bone union in 62 cases (98.4%); the lone exception was in a patient who experienced osteolysis. There were also 3 cases who removed greater trochanter reattachment device due to broken implant and 1 case of dislocation. CONCLUSION: The different fixation methods applied to three distinct groups with varying fractures patterns were successful in achieving proper reduction and fixation of greater trochanteric fractures. We also observed reduced bone union periods when arthroplasty was performed in patients with unstable intertrochanteric fractures. Lastly, we believe these approaches may also aid in achieving early ambulation and early rehabilitations.

Treatment of dens fracture in adults: A report of thirty-two cases.

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.

Human serum opsonization of orthopedic biomaterial particles: protein-binding and monocyte/macrophage activation in vitro.

Wear particles generated after total joint arthroplasty activate monocyte/macrophages and incite formation of a granulomatous periprosthetic tissue associated with bone loss and implant loosening. This study tested the hypothesis that selective opsonization of orthopedic implant biomaterial wear particles by human serum proteins influences monocyte/macrophage activation. Serum protein binding to metallic, polymeric, and ceramic particles was determined by one-dimensional sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Individual proteins bound to particles were subsequently identified using two-dimensional SDS-PAGE, microsequencing techniques, and SWISS-PROT analysis. Effects of selective protein opsonization on particle-induced monocyte/macrophage activation were assessed by quantification of interleukin-1beta, interleukin-6, and tumor necrosis factor-alpha release. Results from one-dimensional gel analyses revealed distinct serum protein-binding patterns specific for each material tested. Two-dimensional gel analysis together with amino acid sequencing of the prominent protein species confirmed the presence of albumin and alpha-1-antitrypsin bound to all particles tested. In contrast to the metallic particles, apolipoprotein was a major species associated with polymeric particles. Opsonization of PMMA particles with purified preparations of each of the identified proteins showed that albumin significantly enhanced particle-induced monocyte/macrophage activation. These data confirm orthopedic biomaterial specific binding of human serum proteins and demonstrate that albumin exacerbates particle-induced monocyte/macrophage activation. Alterations in the chemical and surface properties of orthopedic biomaterials to modulate protein interactions may improve implant longevity.

Results of revision surgery and causes of unstable total knee arthroplasty.

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, ß, 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.

Instrumented ligamentotaxis and stabilization of compression and burst fractures of dorsolumbar and mid-lumbar spines.

BACKGROUND: Controversy continues regarding the best treatment for compression and burst fractures. The axial distraction reduction utilizing the technique employing 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 patients after surgery were braced for ten weeks with activity restriction for 2-4 weeks. The patients were evaluated for change in vertebral body height, sagittal 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 preoperative and postreduction percentile vertebral heights at, zero (immediate postoperative), 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 preoperative, and postoperative at zero, 3, 6 and 12 months followup were 59.0, 36.2,, 36.0, 32.3, and 13.6% respectively. The preoperative 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 followup. 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.

Conservative treatment of tuberculosis of the lumbar and lumbosacral spine.

Fifty-six adults (average age, 38 years) with active tuberculosis of the lumbar and lumbosacral spine were treated conservatively with triple chemotherapy for 12 to 18 months. The minimum followup was 3 years. Three methods of assessments of the chronologic changes of sagittal spinal deformity were used on lateral radiographs of the lumbar spine obtained with the patient standing: deformity, kyphos angles, and total lumbar lordosis. The lumbosacral joint angle was measured for tuberculosis of the lumbosacral joint. The disease healed in all patients with a minimum increase of kyphosis, although in 23 patients there was minimal new involvement of the adjacent vertebral bodies within 6 months of treatment. The pattern of the involved vertebral body collapse in tuberculosis of the lumbar and lumbosacral joints was vertical (telescoping), along a longitudinal axis that minimized the progression of kyphosis. The outcome was judged on the basis of residual kyphosis (British Medical Research Council criteria) and found to be favorable in 96.4% (54 patients). Triple chemotherapy for lumbar and lumbosacral tuberculosis is effective in curing the disease and in minimizing the residual kyphosis through early diagnosis and immediate initiation of chemotherapy. The pattern of vertebral body collapse is the telescoping type, which is the determining factor in minimizing residual spinal deformity.

Pott's paraplegia in patients with severely deformed dorsal or dorsolumbar spines: treatment and prognosis.

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.