Function-Orientated Structural Analysis of the Proximal Human Femur

In his model of the biomechanics of the proximal human femur, Friedrich Pauwels assumes a resultant force acting on the femoral head that is created by the partial body weight and the force of the abductor muscles inserting at the greater trochanter. This model suggests a tensile force in the region of the greater trochanter. An exact examination of the muscle insertions at the greater trochanter resulted in a contrasting hypothesis assuming a local compression stress in the region of the greater trochanter. The aim of this study was to examine which hypothesis is favored by the internal architecture of the proximal femur. Based on the architectural software Allplan (R), we performed an extended analysis of the trabecular structure within the proximal femur using CT scans of 10 human cadaver femora altogether. According to our results, both the medial and the trochanteric trabecular systems are orientated approximately perpendicular to the arcuate trabecular system {[}angles between systems ranging from 84.6 to 93.0 degrees (mean angle 90.7 degrees) and from 80.9 to 86.5 degrees, (mean angle 84.9 degrees), respectively]; furthermore, the medial trabecular system is orientated perpendicular to the epiphysis of the femoral head (mean of angles: 94.7). The biomechanical interpretation of these results strongly supports the idea of compressive stress in the region of the greater trochanter and makes a predominant tensile force of the abductor muscles highly unlikely. Copyright (C) 2009 S. Karger AG, Base

Whole-body magnetic resonance imaging (WBMRI) versus whole-body computed tomography (WBCT) for myeloma imaging and staging

Myeloma-associated bone disease (MBD) develops in about 80-90% of patients and severely affects their quality of life, as it accounts for the majority of mortality and morbidity. Imaging in multiple myeloma (MM) and MBD is of utmost importance in order to detect bone and bone marrow lesions as well as extraosseous soft-tissue masses and complications before the initiation of treatment. It is required for determination of the stage of disease and aids in the assessment of treatment response. Whole-body low-dose computed tomography (WBLDCT) is the key modality to establish the initial diagnosis of MM and is now recommended as reference standard procedure for the detection of lytic destruction in MBD. In contrast, whole-body magnetic resonance imaging (WBMRI) has higher sensitivity for the detection of focal and diffuse plasma cell infiltration patterns of the bone marrow and identifies them prior to osteolytic destruction. It is recommended for the evaluation of spinal and vertebral lesions, while functional, diffusion-weighted MRI (DWI-MRI) is a promising tool for the assessment of treatment response. This review addresses the current improvements and limitations of WBCT and WBMRI for diagnosis and staging in MM, underlining the fact that both modalities offer complementary information. It further summarizes the corresponding radiological findings and novel technological aspects of both modalities

Technique and results after immediate orthotopic replantation of extracorporeally irradiated tumor bone autografts with and without fibular augmentation in extremity tumors

BACKGROUND Reconstruction of the skeletal defects resulting from the resection of bone tumors remains a considerable challenge and one of the possibilities is the orthotopic replantation of the irradiated bone autograft. One technical option with this technique is the addition of a vital autologous fibular graft, with or without microvascular anastomosis. The aim of our study was to evaluate the clinical results of the treatment of our patient cohort with a specific view to the role of fibular augmentation. METHODS Twenty-one patients with 22 reconstructions were included. In all cases, the bone tumor was resected with wide margins and in 21 of them irradiated with 300 Gy. In the first case, thermal sterilization in an autoclave was used. The autograft was orthotopically replanted and stabilized with plates and screws. Fifteen patients underwent an additional fibular augmentation, 8 of which received microvascular anastomoses or, alternatively, a locally pedicled fibular interposition. RESULTS the most common diagnosis was a Ewing sarcoma (8 cases) and the most common location was the femur (12 cases). The mean follow-up time was 70 months (16-154 months). For our statistical analysis, the one case with autoclave sterilization and 3 patients with tumors in small bones were excluded. During follow-up of 18 cases, 55.6% of patients underwent an average of 1.56 revision surgeries. Complete bony integration of the irradiated autografts was achieved in 88.9% of cases after 13.6 months on average. In those cases with successful reintegration, the autograft was shorter (n.s.). Microvascular anastomosis in vascularized fibular strut grafts did not significantly influence the rate of pseudarthrosis. CONCLUSIONS the replantation of extracorporeally irradiated bone autografts is an established method for the reconstruction of bone defects after tumor resection. Our rate of complications is comparable to those of other studies and with other methods of bone reconstruction (e.g. prosthesis). In our opinion, this method is especially well suited for younger patients with extraarticular bone tumors that allow for joint preservation. However, these patients should be ready to accept longer treatment periods

Aneurysmal bone cyst: results of an off label treatment with Denosumab

Background The treatment of aneurysmal bone cysts (ABCs) has evolved and less invasive methods have been tried. Denosumab is a monoclonal antibody which inhibits osteoclasts. It has been shown to be effective in giant cell tumour of bone (GCT) of bone and hence promises some effect also in ABC. We report on 6 patients treated with Denosumab and compare our results to the cases already published. Methods Data of 6 patients with ABCs and patients whose treatment included Denosumab were retrospectively analyzed. Denosumab was used at a dose of 120 mg on days 1, 8, 15 and 29, and every 4 weeks thereafter. In some of these patients the dose was reduced at the end of the treatment. Clinical and radiological responses were evaluated. Results In 4 female and 2 male patients with a mean age of 17 years (range: 6–30 years) the lesions were located in the sacrum (2), in distal radius, distal femur, talus and pelvis. One of the sacral lesions healed after 12 months and has stayed stable for 3 years since. The second patient received 2 years of therapy with recalcification, but recurred 1 year later and is under renewed therapy. The pelvic lesion improved but recurred. This patient has a 13-years history of intermittent therapy including surgery, two pregnancies and remains in a stable situation. The lesion of the talus did not improve with Denosumab after surgery and was complicated by destruction of the ankle joint with osteoarthritis. Recurrent lesions of the distal femur and the distal radius, previously treated by curettage and bone grafting healed under Denosumab and have remained stable for 2 and 3 years, respectively. One case of severe hypercalcemia was observed in a 7-year old child 6 months after discontinuation of Denosumab. Conclusion Denosumab provides a treatment option for ABCs in anatomically critical locations. Adjuvant application might reduce the rate of local recurrence. In young patients, severe rebound hypercalcemia months after discontinuation of Denosumab may occur

Hematopoietic islands mimicking osteoblastic metastases within the axial skeleton

Background Hyperplasia of the hematopoietic bone marrow in the appendicular skeleton is common. In contrast, focal hematopoietic islands within the axial skeleton are a rare entity and can confuse with osteoblastic metastases. This study aimed to characterize typical MRI and CT findings of hematopoietic islands in distinction from osteoblastic metastases to help both radiologists and clinicians, on the one hand, not to overdiagnose this entity and, on the other hand, to decide on a reasonable work-up. Methods We retrospectively analyzed the imaging findings of 14 hematopoietic islands of the axial skeleton in ten patients (nine females, median age = 65.5 years [range, 49–74]) who received both MRI and CT at initial diagnosis between 2006 and 2020. CT-guided biopsy was performed in five cases to confirm the diagnosis, while the other five patients received long-term MRI follow-up (median follow-up = 28 months [range, 6–96 months]). Diffusion-weighted imaging was available in three, chemical shift imaging respectively 18 F- fluorodeoxyglucose PET/CT in two, and Technetium 99 m skeletal scintigraphy in one of the patients. Results All lesions were small (mean size = 1.72 cm 2 ) and showed moderate hypointense signals on T1- and T2-weighted MRI sequences. They appeared isointense to slightly hyperintense on STIR images and slightly enhanced after gadolinium administration. To differentiate this entity from osteoblastic metastases, CT provides important additional information, as hematopoietic islands do not show sclerosis. Conclusions Hematopoietic islands within the axial skeleton can occur and mimic osteoblastic metastases. However, the combination of MRI and CT allows for making the correct diagnosis in most cases

Effect of the defect localization and size on the success of third-generation autologous chondrocyte implantation in the knee joint

Introduction. Femoral and patellar cartilage defects with a defect size > 2.5 cm2 are a potential indication for an autologous chondrocyte implantation (ACI). However, the influence of the localization and the absolute and relative defect size on the clinical outcome has not yet been determined. The purpose of this study is to analyze the influence of the localization and the absolute and relative defect size on the clinical outcome after third-generation autologous chondrocyte implantation. Methods. A total of 50 patients with cartilage defects of the knee were treated with third-generation autologous chondrocyte implantation (Novocart® 3D). A match paired analysis was performed of 25 treated femoral and 25 treated patella defects with a follow-up of three years. MRI data was used to do the manual segmentation of the cartilage layer throughout the knee joint. The defect size was determined by taking the defect size measured in the MRI in relation to the whole cartilage area. The clinical outcome was measured by the IKDC score and VAS pre-operatively and after six, 12, 24, and 36 months post-operatively. Results. IKDC and VAS scores showed a significant improvement from the baseline in both groups. Femoral cartilage defects showed significantly superior clinical results in the analyzed scores compared to patellar defects. The femoral group improved IKDC from 33.9 (SD 18.1) pre-operatively to 71.5 (SD 17.4) after three years and the VAS from 6.9 (SD 2.9) pre-operatively to 2.4 (SD 2.5) after three years. In the patellar group, IKDC improved from 36.1 (SD 12.6) pre-operatively to 54.7 (SD 20.3) after three years and the VAS improved from 6.7 (SD 2.8) pre-operatively to 3.4 (SD 2.) after three years. Regarding the defect size, results showed that the same absolute defect size at med FC (4.8, range 2–15) and patella (4.6, range 2–12) has a significantly different share of the total cartilaginous size of the joint compartment (med FC: 6.7, range 1.2–13.9; pat: 18.9, range 4.0–47.0). However, there was no significant influence of the relative defect size on the clinical outcome in either patellar or femoral localization. Conclusion. Third-generation autologous chondrocyte implantation in ACI-treated femoral cartilage defects leads to a superior clinical outcome in a follow-up of three years compared with patellar defects. No significant influence of the defect size was found in either femoral or patellar cartilage defects

Survival and prognostic factors in conventional G1 chondrosarcoma

Background Chondrosarcoma is the second most frequent malignant bone tumor. Grade I chondrosarcoma (syn.: atypical cartilaginous tumor) is classified as an intermediately and locally aggressive neoplasm and typically is treated less aggressively (i.e., by intralesional curettage). Does the data regarding local recurrence (LR) and metastatic disease justify this? Methods From 1982 to 2014, 37 consecutive patients with G1 chondrosarcoma had been resected or curetted. The margin was defined as R0 (wide resection) or R1 (marginal resection). All patients were followed for evidence of local recurrence or metastatic disease. Overall and recurrence-free survival were calculated, and various potentially prognostic factors were evaluated. Results In 23 patients (62%), the tumor was widely (R0) resected, whereas in 14 patients, (38%) the resection was marginal (R1). Overall survival was 97% after 5 years, 92% after 10 years, and 67% after 20 years. Five-year local recurrence-free survival was 96%. Ten-year local recurrence-free survival was 83%. Local recurrence-free survival showed a significant correlation to margin status but no correlation to location or age. None of the patients with local recurrence died during the follow-up. One patient had metastatic disease at initial presentation, and a further five patients developed metastatic disease during follow-up. Metastatic disease proofed to be a highly significant factor for survival but was not correlated to local recurrence. Conclusions There was no significant correlation between the outcome and the primary tumor location. Marginal resection was a risk factor for LR, but there was no significant difference in the overall survival in patients with or without LR. Metastatic disease (16%) was more common than expected from the literature and a significant predictor for poor overall survival

Is bone marrow edema syndrome a precursor of hip or knee osteonecrosis? Results of 49 patients and review of the literature

PURPOSEDiagnosis of bone marrow edema syndrome (BMES) can be challenging. There is sometimes uncertainty about the correct diagnosis of BMES on morphologic magnetic resonance imaging (MRI), since subchondral findings like lines and spots can be misinterpreted as "beginning" or "possible" avascular osteonecrosis (AVN). The aim of our study was to systematically assess the temporal course of BMES from first diagnosis on MRI until the end of clinical symptoms and the full disappearance of bone marrow edema (BME) to determine whether subchondral lines and spots detected in these patients can develop into osteonecrosis.METHODSIn a combined retrospective and prospective study, we retrieved serial MRI scans of hips and knees with BME from the hospital database. According to clinical and imaging data, all patients with degenerative, infectious/inflammatory, rheumatic, neoplastic conditions and those showing typical osteonecrosis were excluded. We collected all available MRI examinations from first detection of BME until its disappearance. In case edema had not fully resolved in the last available MRI scan, we performed an MRI with an additional dynamic contrast-enhanced (DCE-MRI) sequence. For each MRI scan, we recorded the severity of edema, the presence of subchondral hypointense lines and the presence of subchondral focal hypointense zones on T1-weighted images by two independent readers. The DCE-MRI scans were used to calculate parameter maps to assess the perfusion characteristics.RESULTSThe study comprised 49 patients aged 22–71 years. In total, 171 morphologic and 5 DCE-MRI scans were evaluated. In 44 patients (89.8%), the BMES completely healed without remnants. In 18 of 49 patients (36.7%), a subchondral line was present in the first MRI exam. Nine patients (18.4%) developed a subchondral line within 1–5 months after the first MRI. In total, 27 out of 49 patients (55.1%) had subchondral lines (12 knees, 15 hips) during the timeframe of the study. All subchondral lines disappeared in the timeframe of the study. Subchondral focal hypointense zones were present in 14 out of 49 patients (28.6%): in 9 cases, subchondral focal hypointense zones disappeared after a median of 5.5 months (range, 1–85 months), while in 5 cases, subchondral focal lesions persisted until the end of the study (up to more than 85 months) without edema in the surrounding bone. All persisting subchondral focal lesions were hyperperfused. These 5 patients had associated meniscal lesions. CONCLUSIONOur study shows that subchondral lines and spots found in patients with BMES do not develop into AVN. Subchondral lines, which resemble subchondral insufficiency fractures, are associated with BMES. Subchondral focal T1-hypointense zones do not represent AVN; most probably these areas represent reparative processes within the subchondral bone, where tensile and shear force overload is present due to altered biomechanics

Graft Hypertrophy After Third-Generation Autologous Chondrocyte Implantation Has No Correlation With Reduced Cartilage Quality: Matched-Pair Analysis Using T2-Weighted Mapping

Background: Graft hypertrophy is common after matrix-based autologous chondrocyte implantation (ACI) in the knee joint. However, it is not clear whether graft hypertrophy is a complication or an adjustment reaction in the cartilage regeneration after ACI. Purpose: To analyze the cartilage quality of the ACI regeneration with graft hypertrophy using T2-weighted mapping. Study Design: Cohort study;Level of evidence, 2. Methods: A total of 91 patients with isolated cartilage defects (International Cartilage Repair Society [ICRS] grade III-IV) of the knee were treated with Novocart 3D, a third-generation, matrix-based, ACI procedure in the knee joint. All patients were evaluated with a standardized magnetic resonance imaging protocol after 3, 6, 12, 24, 36, and 48 months postoperatively. For morphological and biochemical assessment, the T2-weighted relaxation times of the ACI grafts as well as the healthy surrounding cartilage were determined. The results of the 20 patients with graft hypertrophy (hypertrophic group) were compared with the results of 21 matched patients without graft hypertrophy (nonhypertrophic group) after ACI. Match-paired analysis was performed by comparison of age, defect size, and body mass index. Results: The T2-weighted relaxation times of the ACI graft showed significant improvement, with values decreasing from 52.1 milliseconds to 33.3 milliseconds after 48 months. After 12 months, the T2-weighted relaxation times were constant and comparable with the healthy surrounding cartilage. Graft hypertrophy was seen in 22% (n = 20) of the patients who underwent ACI. A significant difference in T2-weighted relaxation times between the hypertrophic and nonhypertrophic ACI grafts could not be found except after 36 months (hypertrophic T2-weighted relaxation time/nonhypertrophic T2-weighted relaxation time: 3 months, 48.0/56.4 ms, P = .666;6 months, 45.6/42.5 ms, P = .280;12 months, 39.3/34.7 ms, P = .850;24 months, 34.8/32.2 ms, P =.742;36 months, 34.6/38.2 ms, P = .030;48 months, 34.2/32.3 ms, P = .693). Conclusion: The T2-weighted relaxation time of the ACI graft cartilage showed significant improvements over the observation period of 4 years postoperatively. After 2 years, graft maturation was completed. Graft hypertrophy after ACI was seen in 22% of the patients. Reduced cartilage quality could not be found in patients with graft hypertrophy after ACI

Bone Loss after Allogeneic Haematopoietic Stem Cell Transplantation: A Pilot Study on the Use of Zoledronic Acid

Purpose. Bone loss is a common phenomenon following allogeneic haematopoietic stem cell transplantation (allo-HSCT). The study aimed on tolerance and efficacy of zoledronic acid (ZA) in patients after allo-HSCT. Methods. 40 patients' with osteoporosis or osteopenia were recruited on this phase II study. ZA was given at a dose of 4 mg IV every 3 months for 2 years (yrs). BMD was determined by dual-energy X-ray absorptiometry (LS lumbar spine, FH femur hip). Patients were evaluated for deoxypyridinoline (Dpd) and calcium excretion by longitudinal measurements. Results. 36 patients who had received at least 3 doses of ZA were evaluable. 26 patients had at least two BMD measurements since baseline (BMD group). Among these patients, BMD increased from 0.97 ± 0.15 to 1.10 ± 0.18 g/cm² (LS baseline—2 yrs, Δ+11.6 ± 6.0%, P < 0.001) and from 0.82 ± 0.10 to 0.91 ± 0.10 g/cm² (FH baseline—2 yrs, Δ+7.5 ± 7.0%, P < 0.001). Factors associated with an increase in BMD were younger age, female donor sex, and immunosuppression with CSA/MTX. Conclusion. ZA was generally well tolerated; it increases BMD and reduces Dpd excretion significantly in patients with bone loss after allo-HSCT